Fosfomycin Addition to Poly(D,L-Lactide) Coating Does Not Affect Prophylaxis Efficacy in Rat Implant-Related Infection Model, But That of Gentamicin Does

PubMed Central

Yorukoglu, Ali Cagdas; Kaleli, Ilknur; Bir, Ferda

2016-01-01

Gentamicin is the preferred antimicrobial agent used in implant coating for the prevention of implant-related infections (IRI). However, the present heavy local and systemic administration of gentamicin can lead to increased resistance, which has made its future use uncertain, together with related preventive technologies. Fosfomycin is an alternative antimicrobial agent that lacks the cross-resistance presented by other classes of antibiotics. We evaluated the efficacy of prophylaxis of 10% fosfomycin-containing poly(D,L-lactide) (PDL) coated K-wires in a rat IRI model and compared it with uncoated (Control 1), PDL-coated (Control 2), and 10% gentamicin-containing PDL-coated groups with a single layer of coating. Stainless steel K-wires were implanted and methicillin-resistant Staphylococcus aureus (ATCC 43300) suspensions (103 CFU/10 μl) were injected into a cavity in the left tibiae. Thereafter, K-wires were removed and cultured in tryptic soy broth and then 5% sheep blood agar mediums. Sliced sections were removed from the tibiae, stained with hematoxylin-eosin, and semi-quantitatively evaluated with X-rays. The addition of fosfomycin into PDL did not affect the X-ray and histopathological evaluation scores; however, the addition of gentamicin lowered them. The addition of gentamicin showed a protective effect after the 28th day of X-ray evaluations. PDL-only coating provided no protection, while adding fosfomycin to PDL offered a 20% level protection and adding gentamicin offered 80%. Furthermore, there were 103 CFU level growths in the gentamicin-added group, while the other groups had 105. Thus, the addition of fosfomycin to PDL does not affect the efficacy of prophylaxis, but the addition of gentamicin does. We therefore do not advise the use of fosfomycin as a single antimicrobial agent in coating for IRI prophylaxis. PMID:27806071

A Black Phosphate Conversion Coating on Steel Surface Using Antimony(III)-Tartrate as an Additive

NASA Astrophysics Data System (ADS)

Li, Feng; Wang, Guiping

2016-05-01

A novel black phosphate conversion coating was formed on steel surface through a Zn-Mn phosphating bath containing mainly ZnO, H3PO4, Mn(H2PO4)2, and Ca(NO3)2, where antimony(III)-tartrate was used as the blackening agent of phosphatization. The surface morphology and composition of the coating were characterized by scanning electron microscopy, energy dispersion spectroscopy, and x-ray photoelectron spectroscopy. Corrosion resistance of the coating was studied by potentiodynamic polarization curves and electrochemical impedance spectroscopy. The pH value of the solution had significant influence on the formation and corrosion resistance of the coating. The experimental results indicated that the Sb plays a vital role in the blackening of phosphate conversion coating. The optimal concentration of antimony(III)-tartrate in the phosphating bath used in this experiment was 1.0 g L-1, as higher values reduced the corrosion resistance of the coating. In addition, by saponification and oil seals, the corrosion duration of the black phosphate coating in a copper sulfate spot test can be as long as 20 min.

Methods of Antimicrobial Coating of Diverse Materials

NASA Technical Reports Server (NTRS)

Akse, James R.; Holtsnider, John T.; Kliestik, Helen

2011-01-01

Methods of coating diverse substrate materials with antimicrobial agents have been developed. Originally intended to reduce health risks to astronauts posed by pathogenic microorganisms that can grow on surfaces in spacecraft, these methods could also be used on Earth for example, to ensure sterility of surgical inserts and other medical equipment. The methods involve, generally, chemical preparation of substrate surfaces to enable attachment of antimicrobial molecules to the substrate surfaces via covalent bonds. Substrate materials that have been treated successfully include aluminum, glass, a corrosion-resistant nickel alloy, stainless steel, titanium, and poly(tetrafluoroethylene). Antimicrobial agents that have been successfully immobilized include antibiotics, enzymes, bacteriocins, bactericides, and fungicides. A variety of linkage chem istries were employed. Activity of antimicrobial coatings against gram-positive bacteria, gram-negative bacteria, and fungi was demonstrated. Results of investigations indicate that the most suitable combination of antimicrobial agent, substrate, and coating method depends upon the intended application.

Hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seals, Roland D.

The present disclosure relates generally to hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications. More specifically, the present disclosure relates to hardface coatings that include a network of titanium monoboride (TiB) needles or whiskers in a matrix, which are formed from titanium (Ti) and titanium diboride (TiB.sub.2) precursors by reactions enabled by the inherent energy provided by the process heat associated with coating deposition and, optionally, coating post-heat treatment. These hardface coatings are pyrophoric, thereby generating further reaction energy internally, and may be applied in a functionally graded manner. The hardfacemore » coatings may be deposited in the presence of a number of fluxing agents, beta stabilizers, densification aids, diffusional aids, and multimode particle size distributions to further enhance their performance characteristics.« less

Hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications

DOEpatents

Seals, Roland D.

2015-08-18

The present disclosure relates generally to hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications. More specifically, the present disclosure relates to hardface coatings that include a network of titanium monoboride (TiB) needles or whiskers in a matrix, which are formed from titanium (Ti) and titanium diboride (TiB.sub.2) precursors by reactions enabled by the inherent energy provided by the process heat associated with coating deposition and, optionally, coating post-heat treatment. These hardface coatings are pyrophoric, thereby generating further reaction energy internally, and may be applied in a functionally graded manner. The hardface coatings may be deposited in the presence of a number of fluxing agents, beta stabilizers, densification aids, diffusional aids, and multimode particle size distributions to further enhance their performance characteristics.

Microenvironment-Sensitive Multimodal Contrast Agent for Prostate Cancer Diagnosis

DTIC Science & Technology

2014-10-01

which serve as a contrast agent for Magnetic Resonance Imaging (MRI), coated with a biopolymer (i.e. starch ) to improve biocompatibility, and...size stability (i.e. resisted aggregation) and lower protein binding than the unmodified MNP. The MNPs were also incubated for varying time periods with

Durable, Low-Surface-Energy Treatments

NASA Technical Reports Server (NTRS)

Willis, Paul B.; Mcelroy, Paul M.; Hickey, Gregory S.

1992-01-01

Chemical treatment for creation of durable, low-surface-energy coatings for glass, ceramics and other protonated surfaces easily applied, and creates very thin semipermanent film with extremely low surface tension. Exhibits excellent stability; surfaces retreated if coating becomes damaged or eroded. Uses include water-repellent surfaces, oil-repellent surfaces, antimigration barriers, corrosion barriers, mold-release agents, and self-cleaning surfaces. Film resists wetting by water, alcohols, hydrocarbon solvents, and silicone oil. Has moderate resistance to abrasion, such as rubbing with cloths, and compression molding to polymers and composite materials.

Electrodeposition mechanism and characterization of Ni-Cu alloy coatings from a eutectic-based ionic liquid

NASA Astrophysics Data System (ADS)

Wang, Shaohua; Guo, Xingwu; Yang, Haiyan; Dai, JiChun; Zhu, Rongyu; Gong, Jia; Peng, Liming; Ding, Wenjiang

2014-01-01

The electrodeposition mechanism, microstructures and corrosion resistances of Ni-Cu alloy coatings on Cu substrate were investigated in a choline chloride-urea (1:2 molar ratio) eutectic-based ionic liquid (1:2 ChCl-urea IL) containing nickel and copper chlorides. Cyclic voltammetry showed that the onset reduction potentials for Cu (∼-0.32 V) and for Ni (∼-0.47 V) were close to each other, indicating that Ni-Cu co-deposition could be easily achieved in the absence of complexing agent which was indispensable in aqueous plating electrolyte. Chronoamperometric investigations revealed that Ni-Cu deposits followed the three-dimensional instantaneous nucleation/growth mechanism, thus producing a solid solution. The compositions, microstructures and corrosion resistances of Ni-Cu alloy coatings were significantly dependent on the deposition current densities. Ni-Cu alloy coatings were α-Ni(Cu) solid solutions, and the coating containing ∼17.6 at.% Cu exhibited the best corrosion resistance because of its dense and crack-free structure.

Organosiloxane-grafted natural polymer coatings

DOEpatents

Sugama, Toshifumi

1998-01-01

A new family of polysaccharide graft polymers are provided as corrosion resistant coatings having antimicrobial properties which are useful on light metals such as aluminum, magnesium, zinc, steel and their alloys. Methods of making the polysaccharide graft polymers are also included. The methods of making the polysaccharide graft polymers involve reacting a polysaccharide source with an antimicrobial agent under conditions of hydrolysis-condensation.

Organosiloxane-grafted natural polymer coatings

DOEpatents

Sugama, Toshifumi

1998-12-01

A new family of polysaccharide graft polymers are provided as corrosion resistant coatings having antimicrobial properties which are useful on light metals such as aluminum, magnesium, zinc, steel and their alloys. Methods of making the polysaccharide graft polymers are also included. The methods of making the polysaccharide graft polymers involve reacting a polysaccharide source with an antimicrobial agent under conditions of hydrolysis-condensation. 17 figs.

Non Chromate, ZVOC Coatings for Steel Substrates on Army and Navy Aircraft and Ground Vehicles: Non Chromate Sealers for Zinc Phosphate

DTIC Science & Technology

2017-04-30

Defense, “Chemical Agent Resistant Coating (CARC) System Application Procedures and Quality Control Inspection”, Washington, DC, June 2003. 4. Non ...WP-200906) Non -Chromate, ZVOC Coatings for Steel Substrates on Army and Navy Aircraft and Ground Vehicles Non -Chromate Sealers for Zinc...comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE

Development of Self-Healing Coatings Based on Linseed Oil as Autonomous Repairing Agent for Corrosion Resistance.

PubMed

Thanawala, Karan; Mutneja, Nisha; Khanna, Anand S; Raman, R K Singh

2014-11-11

In recent years corrosion-resistant self-healing coatings have witnessed strong growth and their successful laboratory design and synthesis categorises them in the family of smart/multi-functional materials. Among various approaches for achieving self-healing, microcapsule embedment through the material matrix is the main one for self-healing ability in coatings. The present work focuses on optimizing the process parameters for developing microcapsules by in-situ polymerization of linseed oil as core and urea-formaldehyde as shell material. Characteristics of these microcapsules with respect to change in processing parameters such as stirring rate and reaction time were studied by using optical microscopy (OM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The effectiveness of these microcapsules in coatings was characterized by studying their adhesion, performance, and mechanical properties.

Development of Self-Healing Coatings Based on Linseed Oil as Autonomous Repairing Agent for Corrosion Resistance

PubMed Central

Thanawala, Karan; Mutneja, Nisha; Khanna, Anand S.; Singh Raman, R. K.

2014-01-01

In recent years corrosion-resistant self-healing coatings have witnessed strong growth and their successful laboratory design and synthesis categorises them in the family of smart/multi-functional materials. Among various approaches for achieving self-healing, microcapsule embedment through the material matrix is the main one for self-healing ability in coatings. The present work focuses on optimizing the process parameters for developing microcapsules by in-situ polymerization of linseed oil as core and urea-formaldehyde as shell material. Characteristics of these microcapsules with respect to change in processing parameters such as stirring rate and reaction time were studied by using optical microscopy (OM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The effectiveness of these microcapsules in coatings was characterized by studying their adhesion, performance, and mechanical properties. PMID:28788249

Effect of blowing agents on the oxidation resistance of carbon foams prepared from molten sucrose

NASA Astrophysics Data System (ADS)

Narasimman, R.; Prabhakaran, K.

2013-06-01

We have prepared low density carbon foams from molten sucrose using aluminium nitrate and boric acid blowing agents. A comparative study of the oxidation resistance of the carbon foams prepared using the two blowing agents are reported in the present paper. Oxidation of the carbon foams was evaluated under isothermal and non-isothermal conditions in air atmosphere using thermogravimetric analysis (TGA). We have observed that the alumina produced from the aluminium nitrate blowing agent acts as a catalyst whereas the boron produced from boric acid inhibits the oxidation of the carbon foams. The oxidation resistance of carbon foams increases with boron concentration. The oxidation onset temperature for the carbon foams prepared using boric acid blowing agent was nearly 60°C higher than that prepared using aluminium nitrate blowing agent. Carbon foams prepared using aluminium nitrate blowing agent undergoes complete oxidation at temperature less than 700°C. Whereas that prepared using boric acid blowing agent leave ˜ 50 wt.% residue at 900°C. Further evidence is provided by the kinetic analysis of the TGA using Coats-Redfern (CR) equation.

Tri-Service Corrosion Conference

DTIC Science & Technology

2002-01-18

PREVENTION / CASE STUDIES 63 Issues in the Measurement of Volatile Organic Compounds (VOC’S) in New- 64 Generation Low-VOC Marine Coatings for...Bell Lab’s Corrosion Preventive Compound (MIL-L-87177A Grade B) 95 David H. Horne,ChE., P.E. The Operational Testing of the CPC ACF-50 on the...A. Matzdorf Low Volatile Organic Compound (VOC) Chemical Agent Resistant Coating 601 (CARC) Application Demonstration/Validation Lisa Weiser

Fire Safety Aspects of Polymeric Materials. Volume 8. Land Transportation Vehicles

DTIC Science & Technology

1979-01-01

Resins and Urea - and Melamine - Formaldehyde Resins ," in: Kurylaand Papa (1973). 188 I RtftHfcNCES...ting furfuryl alcohol and an aldehyde — most frequently formaldehyde (Siegfried 1967). Urea is often used as a modifying agent. The resins are hardened... melamine / formaldehyde and phenol/formaldehye resins may find significant utility as a char resistant coating on factory coated wood. 73 /’ I

An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

NASA Astrophysics Data System (ADS)

Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A.

2017-02-01

A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.

An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

PubMed Central

Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A.

2017-01-01

A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance. PMID:28157233

Wear Resistance Properties Reinforcement Using Nano-Al/Cu Composite Coating in Sliding Bearing Maintenance.

PubMed

Liu, Hongtao; Li, Zhixiong; Wang, Jianmei; Sheng, Chenxing; Liu, Wanli

2018-03-01

Sliding bearing maintenance is crucial for reducing the cost and extending the service life. An efficient and practical solution is to coat a restorative agent onto the worn/damaged bearings. Traditional pure-copper (Cu) coating results in a soft surface and poor abrasion resistance. To address this issue, this paper presents a nano-composite repairing coating method. A series of nano-Al/Cu coatings were prepared on the surface of 45 steel by composite electro-brush plating (EBP). Their micro-hardness was examined by a MHV-2000 Vickers hardness tester, and tribological properties by a UMT-2M Micro-friction tester, 3D profiler and SEM. Then, the influence of processing parameters such as nano-particle concentration and coating thickness on the micro-hardness of nano-Al/Cu coating was analyzed. The experimental analysis results demonstrate that, when the nano-Al particle concentration in electrolyte was 10 g/L, the micro-hardness of the composite coating was 1.1 times as much as that of pure-Cu coating. When the Al nano-particle concentration in electrolyte was 20 g/L, the micro-hardness of the composite coating reached its maximum value (i.e., 231.6 HV). Compared with the pure-Cu coating, the hardness and wear resistance of the nano-composite coating were increased, and the friction coefficient and wear volume were decreased, because of the grain strengthening and dispersion strengthening. The development in this work may provide a feasible and effective nano-composite EBP method for sliding bearing repair.

Proximal detection of chemical warfare agents using PMIRRAS

NASA Astrophysics Data System (ADS)

Petryk, Michael W. P.; Marenco, Armando J.

2010-04-01

Non-contact chemical warfare agent detection has been demonstrated on military painted surfaces using polarization modulation infrared reflection-absorption spectroscopy (PMIRRAS). Notably, VX has been detected on chemical agent resistance coating (CARC) paint at a distance of approximately 10 cm. PMIRRAS does not rely on the presence of chemical vapors and is not affected by many common battlefield interferants such as aerosolized dust, water and diesel vapors, etc., making it highly suitable for use in operational environments.

Insect-resistant food packaging film development using cinnamon oil and microencapsulation technologies.

PubMed

Kim, In-Hah; Han, Jaejoon; Na, Ja Hyun; Chang, Pahn-Sik; Chung, Myung Sub; Park, Ki Hwan; Min, Sea C

2013-02-01

Insect-resistant films containing a microencapsulated insect-repelling agent were developed to protect food products from the Indian meal moth (Plodia interpunctella). Cinnamon oil (CO), an insect repelling agent, was encapsulated with gum arabic, whey protein isolate (WPI)/maltodextrin (MD), or poly(vinyl alcohol) (PVA). A low-density polyethylene (LDPE) film was coated with an ink or a polypropylene (PP) solution that incorporated the microcapsules. The encapsulation efficiency values obtained with gum arabic, WPI/MD, and PVA were 90.4%, 94.6%, and 80.7%, respectively. The films containing a microcapsule emulsion of PVA and CO or incorporating a microcapsule powder of WPI/MD and CO were the most effective (P < 0.05) at repelling moth larvae. The release rate of cinnamaldehyde, an active repellent of cinnamaldehyde, in the PP was 23 times lower when cinnamaldehyde was microencapsulated. Coating with the microcapsules did not alter the tensile properties of the films. The invasion of larvae into cookies was prevented by the insect-repellent films, demonstrating potential for the films in insect-resistant packaging for food products. The insect-repelling effect of cinnamon oil incorporated into LDPE films was more effective with microencapsulation. The system developed in this research with LDPE film may also be extended to other food-packaging films where the same coating platform can be used. This platform is interchangeable and easy to use for the delivery of insect-repelling agents. The films can protect a wide variety of food products from invasion by the Indian meal moth. © 2013 Institute of Food Technologists®

LIFE CYCLE ASSESSMENT FOR CHEMICAL AGENT RESISTANT COATING

EPA Science Inventory

This project was sponsored by the Department of Defense Strategic Environmental Research and Development Program (SERDP) and conducted by the U. S. Environmental Protection Agency National Risk Management Research Laboratory (NRMRL). In support of SERDP's objective to develop env...

Sonorensin: A new bacteriocin with potential of an anti-biofilm agent and a food biopreservative

PubMed Central

Chopra, Lipsy; Singh, Gurdeep; Kumar Jena, Kautilya; Sahoo, Debendra K.

2015-01-01

The emergence of antibiotic resistant bacteria has led to exploration of alternative therapeutic agents such as ribosomally synthesized bacterial peptides known as bacteriocins. Biofilms, which are microbial communities that cause serious chronic infections, form environments that enhance antimicrobial resistance. Bacteria in biofilm can be upto thousand times more resistant to antibiotics than the same bacteria circulating in a planktonic state. In this study, sonorensin, predicted to belong to the heterocycloanthracin subfamily of bacteriocins, was found to be effectively killing active and non-multiplying cells of both Gram-positive and Gram-negative bacteria. Sonorensin showed marked inhibition activity against biofilm of Staphylococcus aureus. Fluorescence and electron microscopy suggested that growth inhibition occurred because of increased membrane permeability. Low density polyethylene film coated with sonorensin was found to effectively control the growth of food spoilage bacteria like Listeria monocytogenes and S. aureus. The biopreservative effect of sonorensin coated film showing growth inhibition of spoilage bacteria in chicken meat and tomato samples demonstrated the potential of sonorensin as an alternative to current antibiotics/ preservatives. PMID:26292786

Bacteriophage Mediated Killing of Staphylococcus aureus In Vitro on Orthopaedic K Wires in Presence of Linezolid Prevents Implant Colonization

PubMed Central

Kaur, Sandeep; Harjai, Kusum; Chhibber, Sanjay

2014-01-01

Background Infections of bone and joint tissues following arthroplasty surgeries remain a major challenge in orthopaedic settings. Methicillin resistant Staphylococcus aureus (MRSA) is recognised as an established pathogen in such infections. Combination therapy using linezolid and bacteriophage impregnated in biopolymer was investigated in the present study as an alternative strategy to prevent MRSA colonisation on the orthopaedic implant surface. Methodology Coating of stainless steel orthopaedic grade K-wires was achieved using hydroxypropylmethlycellulose (HPMC) mixed with phage alone, linezolid alone and phage and linezolid together. The potential of these agents to inhibit adhesion of S.aureus (MRSA) 43300 on K-wires was assessed. Coated and naked wires were analysed by scanning electron microscopy (SEM) and fluorescent staining. Result Significant reduction in bacterial adhesion was achieved on phage/linezolid wires in comparison to naked as well as HPMC coated wires. However, maximum reduction in bacterial adherence (∼4 log cycles) was observed on the wires coated with phage-linezolid combination. The frequency of emergence of resistant mutants was also negligible in presence of both the agents. Conclusion This study provides evidence to confirm that local delivery system employing linezolid (a potent protein synthesis inhibitor) along with a broad spectrum lytic bacteriophage (capable of self-multiplication) is able to attack the adhered as well as surrounding bacteria present near the implant site. Unlike other antibiotic based therapies, this combination has the potential to significantly restrict the emergence of resistant mutants, thus paving the way for effective treatment of MRSA associated infection of medical implants. PMID:24594764

Does implant coating with antibacterial-loaded hydrogel reduce bacterial colonization and biofilm formation in vitro?

PubMed

Drago, Lorenzo; Boot, Willemijn; Dimas, Kostantinos; Malizos, Kostantinos; Hänsch, Gertrud M; Stuyck, Jos; Gawlitta, Debby; Romanò, Carlo L

2014-11-01

Implant-related infections represent one of the most severe complications in orthopaedics. A fast-resorbable, antibacterial-loaded hydrogel may reduce or prevent bacterial colonization and biofilm formation of implanted biomaterials. We asked: (1) Is a fast-resorbable hydrogel able to deliver antibacterial compounds in vitro? (2) Can a hydrogel (alone or antibacterial-loaded) coating on implants reduce bacterial colonization? And (3) is intraoperative coating feasible and resistant to press-fit implant insertion? We tested the ability of Disposable Antibacterial Coating (DAC) hydrogel (Novagenit Srl, Mezzolombardo, Italy) to deliver antibacterial agents using spectrophotometry and a microbiologic assay. Antibacterial and antibiofilm activity were determined by broth microdilution and a crystal violet assay, respectively. Coating resistance to press-fit insertion was tested in rabbit tibias and human femurs. Complete release of all tested antibacterial compounds was observed in less than 96 hours. Bactericidal and antibiofilm effect of DAC hydrogel in combination with various antibacterials was shown in vitro. Approximately 80% of the hydrogel coating was retrieved on the implant after press-fit insertion. Implant coating with an antibacterial-loaded hydrogel reduces bacterial colonization and biofilm formation in vitro. A fast-resorbable, antibacterial-loaded hydrogel coating may help prevent implant-related infections in orthopaedics. However, further validation in animal models and properly controlled human studies is required.

Improving Corrosion Resistance of 316L Austenitic Stainless Steel Using ZrO2 Sol-Gel Coating in Nitric Acid Solution

NASA Astrophysics Data System (ADS)

Kazazi, Mahdi; Haghighi, Milad; Yarali, Davood; Zaynolabedini, Masoomeh H.

2018-03-01

In this study, thin-film coating of zirconium oxide (ZrO2) was prepared by sol-gel method and subsequent heat treatment process. The sol was prepared by controlled hydrolysis of zirconium tetrapropoxide using acetic acid and ethanol/acetylacetone mixture as catalyst and chelating agent, respectively, and finally deposited onto the 316L austenitic stainless steel (316L SS) using dip coating method in order to improve its corrosion resistance in nitric acid medium. The composition, structure, and morphology of the coated surface were investigated by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The obtained results from XRD and FTIR state the formation of tetragonal and monoclinic ZrO2 phase. Also, the obtained results from surface morphology investigation by SEM and AFM indicate the formation of smooth, homogeneous and uniform coatings on the steel substrate. Then, the corrosion behavior of stainless steel was investigated in a 1 and 10 M nitric acid solutions using electrochemical impedance spectroscopy and linear polarization test. The obtained results from these tests for ZrO2-coated specimens indicated a considerable improvement in the corrosion resistance of 316L stainless steel by an increase in corrosion potential and transpassive potential, and a decrease in passive current density and corrosion current density. The decrease in passive current density in both the concentration of solutions was two orders of magnitude from bare to coated specimens.

Understanding of the importance of the spore coat structure and pigmentation in the Bacillus subtilis spore resistance to low-pressure plasma sterilization

NASA Astrophysics Data System (ADS)

Raguse, Marina; Fiebrandt, Marcel; Denis, Benjamin; Stapelmann, Katharina; Eichenberger, Patrick; Driks, Adam; Eaton, Peter; Awakowicz, Peter; Moeller, Ralf

2016-07-01

Low-pressure plasmas have been evaluated for their potential in biomedical and defense purposes. The sterilizing effect of plasma can be attributed to several active agents, including (V)UV radiation, charged particles, radical species, neutral and excited atoms and molecules, and the electric field. Spores of Bacillus subtilis were used as a bioindicator and a genetic model system to study the sporicidal effects of low-pressure plasma decontamination. Wild-type spores, spores lacking the major protective coat layers (inner, outer, and crust), pigmentation-deficient spores or spore impaired in encasement (a late step in coat assembly) were systematically tested for their resistance to low-pressure argon, hydrogen, and oxygen plasmas with and without admixtures. We demonstrate that low-pressure plasma discharges of argon and oxygen discharges cause significant physical damage to spore surface structures as visualized by atomic force microscopy. Spore resistance to low-pressure plasma was primarily dependent on the presence of the inner, and outer spore coat layers as well as spore encasement, with minor or less importance of the crust and spore pigmentation, whereas spore inactivation itself was strongly influenced by the gas composition and operational settings.

Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

PubMed

Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

2015-09-02

We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed.

Improved pH buffering agent for sodium hypochlorite

NASA Technical Reports Server (NTRS)

Nash, J. R.; Veeder, L. N.

1969-01-01

Sodium citrate/citric acid was found to be an effective buffer for pH control when used with sodium hypochlorite. The mixture does not corrode aluminum. The buffer appears to form a type of conversion coating that may provide corrosion-resistant properties to aluminum in other applications.

Interpretation of Mechanical and Thermal Properties of Heavy Duty Epoxy Based Floor Coating Doped by Nanosilica

NASA Astrophysics Data System (ADS)

Nikje, M. M. Alavi; Khanmohammadi, M.; Garmarudi, A. Bagheri

Epoxy-nano silica composites were prepared using Bisphenol-A epoxy resin (Araldite® GY 6010) resin obtained from in situ polymerization or blending method. SiO2 nanoparticles were pretreated by a silan based coupling agent. Surface treated nano silica was dispersed excellently by mechanical and ultrasonic homogenizers. A dramatic increase in the interfacial area between fillers and polymer can significantly improve the properties of the epoxy coating product such as tensile, elongation, abrasion resistance, etc.

Defense Technology Area Plan.

DTIC Science & Technology

1996-05-01

Nonpolluting fouling-resistant or fouling-release hull coatings, which exploit low- surface-energy and surface-oriented perfluorinated alkyl compounds ... compounds Novel radioprotective drugs Fieldable biodosimetry capability Modeling for casualties in NBC environments Combined injury treatment protocols...Viral Agents, including encephalomyelitis viruses, variola (smallpox), and filoviridae (e.g., Ebola virus). • Neuroactive Compounds , including

Coating Carbon Fibers With Platinum

NASA Technical Reports Server (NTRS)

Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

2007-01-01

A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

Electrophoretic deposition and electrochemical behavior of novel graphene oxide-hyaluronic acid-hydroxyapatite nanocomposite coatings

NASA Astrophysics Data System (ADS)

Li, Ming; Liu, Qian; Jia, Zhaojun; Xu, Xuchen; Shi, Yuying; Cheng, Yan; Zheng, Yufeng; Xi, Tingfei; Wei, Shicheng

2013-11-01

Novel ternary graphene oxide-hyaluronic acid-hydroxyapatite (GO-HY-HA) nanocomposite coatings were prepared on Ti substrate using anodic electrophoretic deposition (EPD). Hyaluronic acid was employed as charging additive and dispersion agent during EPD. The kinetics and mechanism of the deposition, and the microstructure of the coated samples were investigated using scanning electron microscopy, X-ray diffraction, Raman spectrum, thermo-gravimetric analysis, and microscopic Fourier transform infrared analysis. The results showed that the addition of GO sheets into the HY-HA suspensions could increase the deposition rate and inhibit cracks creation and propagation in the coatings. The corrosion resistant of the resulting samples were evaluated using potentiodynamic polarization method in simulated body fluid, and the GO-HY-HA coatings could effectively improve the anti-corrosion property of the Ti substrate.

Corrosion Prevention for Wheeled Vehicle Systems

DTIC Science & Technology

1993-08-13

The audit objective was to evaluate the effectiveness and efficiency of the Army’s procedures for acquiring corrosion prevention and chemical agent...resistant coatings for wheeled vehicle systems. To accomplish this objective, we reviewed corrosion controls and painting processes. The audit also...included a review of the adequacy of internal controls related to the audit objective.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chaiko, David J.; Leyva, Argentina A.

The invention provides methods for making clay/wax nanocomposites and coatings and films of same with improved chemical resistance and gas barrier properties. The invention further provides methods for making and using emulsions of such clay/wax nanocomposites. Typically, an organophillic clay is combined with a wax or wax/polymer blend such that the cohesion energy of the clay matches that of the wax or wax/polymer blend. Suitable organophilic clays include mica and phyllosilicates that have been surface-treated with edge or edge and surface modifying agents. The resulting nanocomposites have applications as industrial coatings and in protective packaging.

[Study on the preparation and properties of novel silica microporous antireflective coating by sol-gel process].

PubMed

Shang, Meng-Ying; Cao, Lin-Hong; Liu, Miao; Luo, Xuan; Ren, Hong-Bo; Ye, Xin; Tang, Yong-Jian; Jiang, Xiao-Dong

2013-04-01

Silica sol was prepared by acid catalyzed sol-gel process using tetraethylorthosilicate (TEOS) as precursor and dimethyldietoxysilane (DDS) as pore-forming agent. A novel kind of monolayer microporous silica anti-reflective (AR) coating was obtained on K9 glass substrate by dip-coating technique and then heat treated at 500 degrees C. The effects of different DDS/TEOS molar ratios on refractive index, transmittance and hardness were investigated. A positive correlation was found between the transmittance and the DDS/TEOS molar ratio due to the increasing porosity. The maximum transmittance can reach 99.7% with the molar ratio of DDS/TEOS rising to 1 : 1. Meanwhile, the refractive index was found quite close to the ideal value 1.22. Nevertheless, higher molar ratio will lead to a bad film-forming property. On the other hand, the hardness of the coatings decreased with the DDS increasing but still remained more than 2 h when the transmittance reached highest. Besides, these coatings exhibit a well abrasion-resistance and excellent adhesivity. The maximum transmittance was only dropped by 0.071% and 0.112% after abrasion for 500 and 1 000 times respectively. Accelerated corrosion tests indicated that the transmittance of traditional coatings rapidly fell down to the substrate level (-92%) after immersion for 5 min, while the transmittance of our novel coating almost linearly decreased and was kept 93.2% after 56 min. In other words, the environment-resistance of our novel silica AR coating is ten times higher than that of traditional ones. The promotions of the coating performances benefit from its micropore structure (-0. 4 nm) with which water molecule can be effectively prevented. With its high transmittance, good mechanical properties and high environment-resistance, this kind of novel coating has a potential application in the field of solar glass modification to improve its anti-reflective properties.

Preparation of Trivalent Chromium and Rare Earth Composite Conversion Coating on Aluminum Alloy Surface

NASA Astrophysics Data System (ADS)

Huang, Jianzhen

2018-01-01

In this paper, the surface conversion film on 6063 aluminum alloy was prepared by chemical plating process with chromium sulfate, lanthanum sulfate and sodium phosphate as film forming agent. The corrosion resistance and surface morphology of the conversion film were analyzed by pitting corrosion test of copper sulfate and SEM. The results show that when Cr2(SO4)3 is 10 g/L, La2(SO4)3 is 2 g/L, Na3PO4 is 8 g/L, pH value is 3, temperature is 40 °C, reaction time is 10 min, the corrosion resistance of the surface conversion film is the best. The conversion coating is light green, composed of Cr, La, P, Al, O and other elements.

Evaluation of the effects of aging in synthetic saliva solution of both commercial and silanized Nd-Fe-B magnets for dental application

NASA Astrophysics Data System (ADS)

Fabiano, F.; Puliafito, V.; Calabrese, L.; Borsellino, C.; Bonaccorsi, L. M.; Giordano, A.; Fabiano, V.; Cordasco, G.

2016-04-01

Neodymium-iron-boron magnets are able to ensure a magnetic flux with high maximum energy product also at miniaturized size. In the past, due to their marked corrosion in saliva they were unsuccessfully implemented in orthodontic systems. Thereby, we propose a multi-layered organic-inorganic coating able to supply anticorrosion resistance, wear resistance and durability to the whole assembly. We evaluated the influence on the magnetic force of commercial nickel plated and silanized Nd-Fe-B during aging time in synthetic Fusayama saliva. Two magnets based-micromagnetic simulations were performed in order to analyze the magnetic field generated which is linked to the magnetic force. Our key results underline that the proposed hybrid coating does not affect the magnetic force of Nd-Fe-B magnets, moreover, preventing corrosion degradation in aggressive solution. Thus the limiting aspects avoiding the use of Nd-Fe-B magnets for orthodontic and prosthodontic applications can be overcome by using silane agents as surface coating.

Potentiodynamic studies of Ni-P-TiO2 nano-composited coating on the mild steel deposited by electroless plating method

NASA Astrophysics Data System (ADS)

Uttam, Vibha; Duchaniya, R. K.

2016-05-01

Now a days, corrosion studies are important for reducing the wastage of metals. The importance of corrosion studies is two folds i.e. first is economic, including the reduction of material losses resulting from the wasting away or sudden failure of materials and second is conservation Electroless process is an autocatalytic reduction method in which metallic ions are reduced in the solution. Nanocomposite coatings of Ni-P-TiO2 on mild steel are deposited by varying volume of TiO2 nano-powder by electroless method from Ni-P plating bath containing Nickel Sulphate as a source of nickel ions, sodium hypophosphite as the reducing agent, lactic acid as a complexing agents and TiO2 nano powder. Electroless Ni-P-TiO2 coating have been widely used in the chemical process industries, mechanical industries, electronic industries and chloroalkali industries due to their excellent corrosion with mechanical properties. In the present work, deposition of Ni-P alloy coating and Ni-P-TiO2 nanocomposited coatings were done on the mild steel and corrosion properties were studied with Potentio-dynamic polarization measurements method in 3.5 wt% sodium chloride solution. It showed in the experiments that Ni-P-TiO2 nanocomposited coating has better corrosion resistance as comparedthan Ni-P alloy coating. Morphological studies were done by field emission scanning electron microscopy (FESEM), energy-dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). These studies confirmed the deposition of Ni-P alloy coating and Ni-P-TiO2 nanocomposited coating.

Corrosion evaluation of zirconium doped oxide coatings on aluminum formed by plasma electrolytic oxidation.

PubMed

Bajat, Jelena; Mišković-Stanković, Vesna; Vasilić, Rastko; Stojadinović, Stevan

2014-01-01

The plasma electrolytic oxidation (PEO) of aluminum in sodium tungstate (Na(2)WO(4) · (2)H(2)O) and Na(2)WO(4) · (2)H(2)O doped with Zr was analyzed in order to obtain oxide coatings with improved corrosion resistance. The influence of current density in PEO process and anodization time was investigated, as well as the influence of Zr, with the aim to find out how they affect the chemical content, morphology, surface roughness, and corrosion stability of oxide coatings. It was shown that the presence of Zr increases the corrosion stability of oxide coatings for all investigated PEO times. Evolution of EIS spectra during the exposure to 3% NaCl, as a strong corrosive agent, indicated the highest corrosion stability for PEO coating formed on aluminum at 70 mA/cm(2) for 2 min in a zirconium containing electrolyte.

Nanocryl Coating of PMMA Complete Denture Base Materials to Prevent Scratching.

PubMed

Fathi, Hawa M; Benonn, Hajer A; Johnson, Anthony

2017-09-01

The surface of polymethylmethacrylate (PMMA) is vulnerable to indentation by hard objects that may contribute to abrade the material surface and subject it to wear. This phenomenon promotes an increase in the surface roughness leading to microbial colonisation which can endanger the general health of wearers and damage the intra-oral prosthesis. The aim of this study is to investigate the effect of three different nanocryl coating agents (Easy Glaze, G-Coat Plus and Formulation XP) on surface roughness and thickness of PMMA material after a simulating cleaning process utilizing an electric toothbrush and three different dentifrices (pastes and immersion). Acrylic uncoated discs were used as a control group. The results showed that the G-Coat Plus coating agent had less changes in the surface roughness and thickness layer whereas the immersion cleaner revealed less abrasion effect compared with the paste cleaners which could be considered the most suitable cleaner to provide lower abrasivenes and good removal of organic debris. However, using nanofilled sealants did not demonstrate significant improvement in reducing surface roughness p ⟩ 0.05. Nevertheless, it could provide some protection against wearing to the acrylic resin surface during tooth brushing and may provide better resistance to microbial colonisation. Copyright© 2017 Dennis Barber Ltd.

Hydrophilic nano-silica coating agents with platinum and diamond nanoparticles for denture base materials.

PubMed

Yoshizaki, Taro; Akiba, Norihisa; Inokoshi, Masanao; Shimada, Masayuki; Minakuchi, Shunsuke

2017-05-31

Preventing microorganisms from adhering to the denture surface is important for ensuring the systemic health of elderly denture wearers. Silica coating agents provide high hydrophilicity but lack durability. This study investigated solutions to improve the durability of the coating layer, determine an appropriate solid content concentration of SiO 2 in the silica coating agent, and evaluate the effect of adding platinum (Pt) and diamond nanoparticles (ND) to the agent. Five coating agents were prepared with different SiO 2 concentrations with/without Pt and ND additives. The contact angle was measured, and the brush-wear test was performed. Scanning electron microscopy was used to investigate the silica coating layer. The appropriate concentration of SiO 2 was found to be 0.5-0.75 wt%. The coating agents with additives showed significantly high hydrophilicity immediately after coating and after the brush-wear test. The coating agents with/without additives formed a durable coating layer even after the brush-wear test.

Preparation and mechanism analysis of an environment-friendly maize seed coating agent.

PubMed

Zeng, Defang; Fan, Zhao; Tian, Xu; Wang, Wenjin; Zhou, Mingchun; Li, Haochuan

2018-06-01

Traditional seed coating agents often contain toxic ingredients, which contaminate the environment and threaten human health. This paper expounds a method of preparing a novel environment-friendly seed coating agent for maize and researches its mechanism of action. The natural polysaccharide polymer, which is the main active ingredient of this environment-friendly seed coating agent, has the characteristics of innocuity and harmlessness, and it can replace the toxic ingredients used in traditional seed coating agents. This environment-friendly seed coating agent for maize was mainly made up of the natural polysaccharide polymer and other additives. The field trials results showed that the control efficacy of Helminthosporium maydis came to 93.72%, the anti-feeding rate of cutworms came to 81.29%, and the maize yield was increased by 17.75%. Besides, the LD 50 value (half the lethal dose in rats) of this seed coating agent was 10 times higher than that of the traditional seed coating agents. This seed coating agent could improve the activity of plant protective enzymes (peroxidase, catalase and superoxidase dismutase) and increase the chlorophyll content. This seed coating agent has four characteristics of disease prevention, desinsectization, increasing yield and safety. Results of mechanism analyses showed that this seed coating agent could enhance disease control effectiveness by improving plant protective enzymes activity and increase maize yield by improving chlorophyll content. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Formation of a hydrophobic and corrosion resistant coating on magnesium alloy via a one-step hydrothermal method.

PubMed

Zheng, Tianxu; Hu, Yaobo; Zhang, Yuxin; Pan, Fusheng

2017-11-01

A hydrophobic coating was fabricated on the surface of magnesium alloy using a simple one-step hydrothermal method with the use of environmentally friendly agent. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and contact angle test were used to characterize the surfaces. Corrosion behavior in a 3.5wt.% NaCl solution was evaluated using OCP time curves test, potentiodynamic polarization test and EIS analysis. The findings show that the substrate is covered by the coating of magnesium hydroxide and magnesium stearate, reaching a contact angle of around 146°. Corrosion behavior show huge improvement, the progress with increase of treatment time could be related to the increased growth rate of coating. Copyright © 2017 Elsevier Inc. All rights reserved.

The Effects of Curcuma Longa on the Functionality of Pigmentation for Thin Film Coating

NASA Astrophysics Data System (ADS)

Marsi, N.; Rus, A. Z. M.; Tan, N. A. M. S.

2017-08-01

This project presents the effects of turmeric (Curcuma Longa) on the functionality of pigmentation was carried out to improve the sustainability, environment impact and reduction of potential cost saving without sacrificing the performance of thin film coating. The Curcuma Longa pigment was extracted by grating the turmeric into small particles at different percentages which is 20%, 40%, 60% and 80% of Curcuma Longa pigment with 3, 6 and 9 layers of coating. The different percentages of Curcuma Longa pigment was formulated and synthesized with polyols by crosslinking agent of glycerol and calcium carbonate into temperature at 140 °C for 2 hours. The results of water droplet test (ASTM D5964) showed the water contact angle was achieved the optimum superhydrophobic characteristic up to 60% of Curcuma Longa at 153°. The formulation of 60% Curcuma Longa was revealed the optimum adhesion resistance test with no flaking and detachment when the coating applied at 9 layers in the classification grading of adhesion test at 5B. It is indicated that the adhesion resistance of thin film coating on metal substrate was obviously increased as the layer of coating as well as the Curcuma Longa pigment percentage up to 60% at 9 layers. This project also highlighted the potential of Curcuma Longa pigment to produce quality in the natural pigmentation as a replacement synthetic pigment which is long-term health hazards.

Anti-corrosion mechanism of epoxy-resin and different content Fe2O3 coatings on magnesium alloy

NASA Astrophysics Data System (ADS)

Jin, Tao; Kong, Fan-mei; Bai, Rui-qin; Zhang, Ru-liang

2016-12-01

In this study, anti-corrosion coatings were prepared and coated successfully on magnesium alloy substrates by mixing nanopowders, solvent, curing agent with epoxy resin. The effect of the amount of iron trioxide (Fe2O3) on the adhesion strength and corrosion resistance on magnesium alloy was investigated with standard protocols, and electrochemical measurements were also made in 3.5 wt.% NaCl solutions. The surface morphology and corrosion mechanism after corrosion tests was characterized using FESEM analysis. Nanoparticles in matrix acted as filler, and interstitial cross-linked spaces and other coating artifacts regions (micro cracks and voids) would all affect the anti-corrosion properties of coating. The results showed the proper powder content not only provided adhesion strength to these coatings but also improved obviously their anticorrosion. Hydrogen bound to the amine nitrogen (1N) could take part in the curing process rather than hydrogen of the amide site due to the smaller Δ G and the more stable configuration.

Effect of salivary pH on diametral tensile strength of glass ionomer cement coated with coating agent

NASA Astrophysics Data System (ADS)

Farahdillah; Triaminingsih, S.; Eriwati, Y. K.

2017-08-01

The aim of this study was to analyze the effect of salivary pH to diametral tensile strength of glass ionomer cement (GIC) coated with a coating agent. GIC specimens coated with varnish and nano-filled coating agent were stored in artificial saliva at pH values of 4.5, 5.5, and 7 for 24 h at 37°C, then the diametral tensile strength was tested by universal testing machine. Results showed that there was no significant difference in the diametral tensile strength of the GIC coated with varnish and nano-filled coating agent with decreasing of salivary pH (p < 0.05). It can be concluded that salivary pH does not affect the diametral tensile strength of GIC coated by varnish or nano-filled coating agent

Alkali Silicate Vehicle Forms Durable, Fireproof Paint

NASA Technical Reports Server (NTRS)

Schutt, John B.; Seindenberg, Benjamin

1964-01-01

The problem: To develop a paint for use on satellites or space vehicles that exhibits high resistance to cracking, peeling, or flaking when subjected to a wide range of temperatures. Organic coatings will partially meet the required specifications but have the inherent disadvantage of combustibility. Alkali-silicate binders, used in some industrial coatings and adhesives, show evidence of forming a fireproof paint, but the problem of high surface-tension, a characteristic of alkali silicates, has not been resolved. The solution: Use of a suitable non-ionic wetting agent combined with a paint incorporating alkali silicate as the binder.

Potentiodynamic studies of Ni-P-TiO{sub 2} nano-composited coating on the mild steel deposited by electroless plating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uttam, Vibha, E-mail: vibhauttam74@gmail.com; Duchaniya, R. K., E-mail: rkduchaniya.meta@mnit.ac.in

2016-05-06

Now a days, corrosion studies are important for reducing the wastage of metals. The importance of corrosion studies is two folds i.e. first is economic, including the reduction of material losses resulting from the wasting away or sudden failure of materials and second is conservation Electroless process is an autocatalytic reduction method in which metallic ions are reduced in the solution. Nanocomposite coatings of Ni-P-TiO{sub 2} on mild steel are deposited by varying volume of TiO{sub 2} nano-powder by electroless method from Ni-P plating bath containing Nickel Sulphate as a source of nickel ions, sodium hypophosphite as the reducing agent,more » lactic acid as a complexing agents and TiO{sub 2} nano powder. Electroless Ni-P-TiO{sub 2} coating have been widely used in the chemical process industries, mechanical industries, electronic industries and chloroalkali industries due to their excellent corrosion with mechanical properties. In the present work, deposition of Ni-P alloy coating and Ni-P-TiO{sub 2} nanocomposited coatings were done on the mild steel and corrosion properties were studied with Potentio-dynamic polarization measurements method in 3.5 wt% sodium chloride solution. It showed in the experiments that Ni-P-TiO{sub 2} nanocomposited coating has better corrosion resistance as comparedthan Ni-P alloy coating. Morphological studies were done by field emission scanning electron microscopy (FESEM), energy–dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). These studies confirmed the deposition of Ni-P alloy coating and Ni-P-TiO{sub 2} nanocomposited coating.« less

Citrus psorosis virus coat protein-derived hairpin construct confers stable transgenic resistance in citrus against psorosis A and B syndromes.

PubMed

De Francesco, A; Costa, N; García, M L

2017-04-01

Citrus psorosis virus (CPsV) is the causal agent of psorosis, a serious and widespread citrus disease. Two syndromes of psorosis, PsA and PsB, have been described. PsB is the most aggressive and rampant form. Previously, we obtained Pineapple sweet orange plants transformed with a hairpin construct derived from the CPsV coat protein gene (ihpCP). Some of these plants were resistant to CPsV 90-1-1, a PsA isolate homologous to the transgene. In this study, we found that expression of the ihpCP transgene and siRNA production in lines ihpCP-10 and -15 were stable with time and propagation. In particular, line ihpCP-15 has been resistant for more than 2 years, even after re-inoculation. The ihpCP plants were also resistant against a heterologous CPsV isolate that causes severe PsB syndrome. Line ihpCP-15 manifested complete resistance while line ihpCP-10 was tolerant to the virus, although with variable behaviour, showing delay and attenuation in PsB symptoms. These lines are promising for a biotech product aimed at eradicating psorosis.

Novel Antibacterial Coating on Orthopedic Wires To Eliminate Pin Tract Infections

PubMed Central

Gil, Dmitry; Shuvaev, Sergey; Frank-Kamenetskii, Anastasia; Reukov, Vladimir; Gross, Christopher

2017-01-01

ABSTRACT Novel approaches to the prevention of microbial infections after the insertion of orthopedic external fixators are in great demand because of the extremely high incidence rates of such infections, which can reach up to 100% with longer implant residence times. Monolaurin is an antimicrobial agent with a known safety record that is broadly used in the food and cosmetic industries; however, its use in antimicrobial coatings of medical devices has not been studied in much detail. Here, we report the use of monolaurin as an antibacterial coating on external fixators for the first time. Monolaurin-coated Kirschner wires (K-wires) showed excellent antibacterial properties against three different bacterial strains, i.e., methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus epidermidis. Approximately 6.0-log reductions of both planktonic and adherent bacteria were achieved using monolaurin-coated K-wires, but monolaurin-coated K-wires did not show any observable cytotoxicity with mouse osteoblast cell cultures. Overall, monolaurin-coated K-wires could be promising as potent antimicrobial materials for orthopedic surgery. PMID:28483964

Clinical performance of a glass ionomer sealant protected with two different resin-based agents over a 2-year follow-up period.

PubMed

Ulusoy, A T; Tunc, E S; Bayrak, Ş

2017-03-01

To evaluate the effects of two different resin coating materials on the clinical performance of a conventional glass ionomer sealant. Permanent first mandibular molars of 60 children aged 6-9 years were sealed with Fuji VII. In each child, G-Coat Plus coating agent was applied to molars on one side and Heliobond coating agent to molars on the opposite side of the mouth. Clinical evaluations were carried out at 1, 6, 12, 18 and 24 months after sealant and coating application. At 1, 6, 12, 18 and 24 months after sealant and coating application, total sealant retention rates were 88%, 40%, 19%, 15% and 9% for molars coated with G-Coat Plus, and 93%, 47%, 17%, 15% and 7% for those coated with Heliobond. The differences between the two coating agents were not statistically significant (p>0.05). No incidence of caries was observed in either group during the two-year evaluation period. Wilcoxon signed rank test was used to compare differences in retention rates and caries incidence by coating agent. Although retention rates of Fuji VII were relatively low and similar for both resin coating agents tested, dental caries were not observed in either group during the 24-month study period. In children with a high risk of caries and partially erupted molars, the use of a glass ionomer sealant with a resin-based coating agent should be encouraged.

Electrically resistive coating for remediation (regeneration) of a diesel particulate filter and method

DOEpatents

Phelps, Amanda C [Malibu, CA; Kirby, Kevin K [Calabasas Hills, CA; Gregoire, Daniel J [Thousand Oaks, CA

2012-02-14

A resistively heated diesel particulate filter (DPF). The resistively heated DPF includes a DPF having an inlet surface and at least one resistive coating on the inlet surface. The at least one resistive coating is configured to substantially maintain its resistance in an operating range of the DPF. The at least one resistive coating has a first terminal and a second terminal for applying electrical power to resistively heat up the at least one resistive coating in order to increase the temperature of the DPF to a regeneration temperature. The at least one resistive coating includes metal and semiconductor constituents.

t-Butyl-Oxycarbonylated Diamines as Building Blocks for Isocyanate-Free Polyurethane/Urea Dispersions and Coatings.

PubMed

Ma, Shuang; Zhang, Huiyi; Sablong, Rafaël J; Koning, Cor E; van Benthem, Rolf A T M

2018-05-01

t-Butyl-oxycarbonylated diamines ("di-Boc-carbamates") are investigated as dicarbamate monomers for diamine/dicarbamate polymerizations. Polyureas (PUs) and polyurethanes (PURs) with high molecular weights are prepared from stoichiometric polymerizations of diamines or diols with N-N'-di-t-butyl-oxycarbonyl isophorone diamine (DiBoc-IPDC) using KOt-Bu as a catalyst, while gelation is observed when an excess of DiBoc-IPDC is used with respect to the diamines or diols. Stable dispersions are obtained from PUs and PURs with 3,3'-diamino-N-methyldipropylamine (DMDPA) as internal dispersing agent. The corresponding PU-based coatings exhibit superior mechanical properties and solvent resistances compared to the polyurethane urea coatings synthesized from diols, DiBoc-IPDC, and DMDPA. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of Tape Adhesion to Chemical Agent Resistant Coatings

DTIC Science & Technology

2015-01-01

use by OEM’s and depots. More specifically, each tape was tested on water dispersible and solvent borne polyurethane topcoats in the two most common...andGenerally, systems formulated to be water dispersible produced films that were slightly hydrophilic (water contact angle < 90°) whereas systems...8). Table 8: Average water contact angle of various CARC systems. advancing contact angle of water (degrees) waterborne polyurethane

Improving the Army’s Next Effort in Technology Forecasting

DTIC Science & Technology

2010-09-01

Health Maintenance— ability to make the robotic system more robust and to provide maintenance capabilities for self -monitoring, diagnostics, and...exhibit a verity of responses, including self -sensing and self - healing activities.43 A team of chemists and materials scientists led by the Moore...ultimately lead to i) applications in vehicles, including self -repairing armor, rubber , and coatings resistant to chemical agents, ii) aerospace

Performance Evaluation of Hap-Free Paint Strippers vs. Methylene-Chloride-Based Strippers for Removing Army Chemical Agent Resistant Coatings (CARC)

DTIC Science & Technology

2006-06-01

Preparation..........................................................................................................3 2.2 Alternatives Selection ...water-borne panels were green. 2.2 Alternatives Selection The Gap Assessment Report generated by CTC/NDCEE identified many HAP-free alternatives to...strip times (as reported by the vendor) of many of the products. ARL used this information to select the alternatives to be included in its test

(Mechanisms of inhibition of viral replication in plants)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-01-01

During the last year we have made a number of important observations in the fields of virology and plant molecular biology. By directly sequencing Tomato Mosaic Virus (ToMV) movement genes, previously undetected sequence alterations common to specific viral strains were found. The difficulty in regenerating transgenic tomato plants containing the Tm-2 gene was overcome. Tobacco plants transformed with Cucumber Mosaic Virus (CMV) are being characterized. Analysis of transgenic tobacco plants expressing CMV coat protein have shown no correlation between coat protein expression and level of resistance. Specific amino acid changes have been found to correlate with CMV resistance breaking andmore » degree of pathogenicity. Satellite RNAs are shown to be too unstable for use as a biological control agent. The aphid transmission domain CMV has been localized to one (or more) of three amino acids; constructs have been made to determine the exact amino acids involved. 15 refs.« less

The effect of salivary pH on diametral tensile strength of resin modified glass ionomer cement coated with coating agent

NASA Astrophysics Data System (ADS)

Ismayanti, D.; Triaminingsih, S.; Eriwati, Y. K.

2017-08-01

The aim of this study was to evaluate the effect of artificial saliva with different acidities on the diametral tensile strength of Resin Modified Glass Ionomer Cement (RMGIC) coated with varnish and nanofilled coating agent. The specimens coated with coating agents were immersed in artificial saliva with pH of 4.5, 5.5, and 7 for 24 hours in an incubatorat 37°C. The diametral tensile strength of the specimens was tested with Universal Testing Machine. There were no significant differences on the diametral tensile strength of all specimens that were put into groups based on the acidity of the saliva and the type of coating agent (p>0.05). Both varnish and nanofilled coating agent stayed on the RMGIC in the acidic condition that simulated the true condition of oral cavity in people with high caries risk for the 24 hours of maturation.

Morphology evaluation of ZrO2 dip coating on mild steel and its corrosion performance in NaOH solution

NASA Astrophysics Data System (ADS)

Anwar, M. A.; Kurniawan, T.; Asmara, Y. P.; Harun, W. S. W.; Oumar, A. N.; Nandyanto, A. B. D.

2017-10-01

In this work, the morphology of ZrO2 thin film from dip coating process on mild steel has been investigated. Mild steel was dip-coated on solution made of zirconium butoxide as a precursor, ethanol as solvent, acetylacetone as chelating agent and water for hydrolysis. Number of dipping was adjusted at 3, 5 and 7 times. The dipped sample then annealed at 350°C for two hours by adjusting the heating rate at 1°C/min respectively. The optical microscope showed that micro-cracks were observed on the surface of the coating with its concentration reduced as dipping sequence increased. The XRD result showed that annealing process can produce polycrystalline tetragonal-ZrO2. Meanwhile, SEM image showed that the thicknesses of the ZrO2 coatings were in between 400-600 nm. The corrosion resistance of uncoated and coated substrates was studied by polarization test through potentio-dynamic polarization curve at 1mV/s immersed in with 3.5% NaCl. The coating efficiency was improved as the number of layer dip coated increased, which showed improvement in corrosion protection.

A Systems Approach to Depaint Chemistry

DTIC Science & Technology

2009-02-01

continuous colored film by curing through solvent evaporation, oxidation, catylization or other means. – Vehicle: Film former, binder, resin or polymer...impart large changes in properties. – Suspending agents – Driers – Anti-Skinning Agents – Wetting Agents – Anti- Foaming Agents – Coalescing Agents ...volatile stripper inside the coating. Paint Release Agent Coating Removal Mechanism Zone1: PRA Layer Zone2: PRA Initial Permeation into coating system Epoxy

The effect of compaction parameters and dielectric composition on properties of soft magnetic composites

NASA Astrophysics Data System (ADS)

Xiao, Ling; Sun, Y. H.; Yu, Lie

2011-07-01

This paper investigated the effect of compaction parameters and dielectric composition on mechanical, magnetic and electrical properties of iron-organosilicon epoxy resin soft magnetic composites. In this work, iron powders with high purity were covered by an organic material (organosilicon epoxy resin) and then by coupling agent (KH-550). The coated powders were then cold compacted at 600, 800 and 1000 MPa and cured under vacuum respectively. The results show that the saturation magnetic flux density and electrical resistivity are dependent on compaction pressure and resin content. Increase in the organic phase content leads to decrease of the saturation magnetic flux density, while increase of the electrical resistivity. Furthermore, the samples with 0.9 wt% resins + 0.1 wt% coupling agent at compaction pressure of 800 MPa shows better properties than the others.

Nanofabrication and characterization of PVA-organofiller/Ag nanocoatings on pMAD plasmids

NASA Astrophysics Data System (ADS)

Erdonmez, D.; Mosayyebi, S.; Erkan, K.; Salimi, K.; Nagizade, N.; Saglam, N.; Rzayev, Z. M. O.

2014-11-01

Nowadays, the most important problem in microbial researches is bacterial resistance which is carried out by DNA plasmids against antibacterial agents. The effect of antibacterial nanoparticles on bacteria is remarkable, but studies on the interactions of these particles with plasmids do not search or there are no adequate studies. We proposed that the nanoparticles, which are disrupted the self-assembled structure of plasmids, may decrease the resistance of bacteria, and therefore, increase the activity of utilized antibacterial agents. In this work, we synthesized polymer nanofiber webs samples by electrospinning technique from pure water solution of nanocomposites with different contents of silver nanoparticles, and surface morphology of nanofibers composites were characterized by SEM microscopy. Their interactions with pMAD DNA plasmids were investigated. It was demonstrated that the synthesized Ag-carrying nanohybrid composites with higher surface contacted areas were significantly inhibited the activity of plasmid DNA against bacterial resistance. Agreeing with obtained results, synthesized nanofiber coatings can be recommended for the widely applications in nanobiotechnology, nanomedicine, and bioengineering processing.

Relevant insight of surface characterization techniques to study covalent grafting of a biopolymer to titanium implant and its acidic resistance

NASA Astrophysics Data System (ADS)

D'Almeida, Mélanie; Amalric, Julien; Brunon, Céline; Grosgogeat, Brigitte; Toury, Bérangère

2015-02-01

Peri-implant bacterial infections are the main cause of complications in dentistry. Our group has previously proposed the attachment of chitosan on titanium implants via a covalent bond to improve its antibacterial properties while maintaining its biocompatibility. A better knowledge of the coating preparation process allows a better understanding of the bioactive coating in biological conditions. In this work, several relevant characterization techniques were used to assess an implant device during its production phase and its resistance in natural media at different pH. The titanium surface was functionalized with 3-aminopropyltriethoxysilane (APTES) followed by grafting of an organic coupling agent; succinic anhydride, able to form two covalent links, with the substrate through a Ti-O-Si bond and the biopolymer through a peptide bond. Each step of the coating synthesis as well as the presence confirmation of the biopolymer on titanium after saliva immersion was followed by FTIR-ATR, SEM, EDS, 3D profilometry, XPS and ToF-SIMS analyses. Results allowed to highlight the efficiency of each step of the process, and to propose a mechanism occurring during the chitosan coating degradation in saliva media at pH 5 and at pH 3.

Genetic transformation of sweet orange with the coat protein gene of Citrus psorosis virus and evaluation of resistance against the virus.

PubMed

Zanek, María Cecilia; Reyes, Carina Andrea; Cervera, Magdalena; Peña, Eduardo José; Velázquez, Karelia; Costa, Norma; Plata, Maria Inés; Grau, Oscar; Peña, Leandro; García, María Laura

2008-01-01

Citrus psorosis is a serious viral disease affecting citrus trees in many countries. Its causal agent is Citrus psorosis virus (CPsV), the type member of genus Ophiovirus. CPsV infects most important citrus varieties, including oranges, mandarins and grapefruits, as well as hybrids and citrus relatives used as rootstocks. Certification programs have not been sufficient to control the disease and no sources of natural resistance have been found. Pathogen-derived resistance (PDR) can provide an efficient alternative to control viral diseases in their hosts. For this purpose, we have produced 21 independent lines of sweet orange expressing the coat protein gene of CPsV and five of them were challenged with the homologous CPV 4 isolate. Two different viral loads were evaluated to challenge the transgenic plants, but so far, no resistance or tolerance has been found in any line after 1 year of observations. In contrast, after inoculation all lines showed characteristic symptoms of psorosis in the greenhouse. The transgenic lines expressed low and variable amounts of the cp gene and no correlation was found between copy number and transgene expression. One line contained three copies of the cp gene, expressed low amounts of the mRNA and no coat protein. The ORF was cytosine methylated suggesting a PTGS mechanism, although the transformant failed to protect against the viral load used. Possible causes for the failed protection against the CPsV are discussed.

Characterization and Properties of Micro-arc Composite Ceramic Coatings on Magnesium Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Long; Jiang, Bailing; Ge, Yanfeng

2013-05-21

Magnesium alloys are of growing interest for many industrial applications due to their favorable strength-to-weight ratio and excellent cast ability. However, one of the limiting factors in the use of magnesium on production vehicles is its poor corrosion resistance. Micro-arc Composite Ceramic (MCC) coatings on AZ91D magnesium alloys were prepared in combination with Micro-arc Oxidation (MAO) and electrophoresis technologies. The microstructure, corrosion resistance, abrasion resistance, stone impact resistance, thermal shock resistance and adhesion of MCC coating were studied, respectively. The surface and cross-section morphologies of MAO and MCC coating showed that the outer organic coating filled the holes on themore » surface of the MAO coating. It acted as a shelter on the MAO coating surface when the MCC coatings were exposed to corrosive environments. The corrosion resistance of the MCC coating was characterized by a copper-accelerated acetic acid salt spray test. The testing results showed that the creep back from scribe lines was less than 1mm and completely fit the evaluation standard. The composite structure of the MCC coating vastly improved the corrosion resistance of Mg alloys. According to testing standards, the resistance to abrasion, stone impact resistance, thermal shock resistance and adhesion of MCC coatings completely met the evaluation standard requirements. The MCC coated AZ91D magnesium alloys possessed excellent properties; this is a promising corrosion and wear resistance surface treatment technology on magnesium alloys for production vehicles.« less

A Nanolayer Copper Coating for Prevention Nosocomial Multi-Drug Resistant Infections

DTIC Science & Technology

2016-10-01

done using a standard antimicrobial assay defined in ASTM method E2149-01 for determining antibacterial activity of immobilized agents under...are optimized for bacterial growth and do not represent typical conditions. Therefore, most studies reporting on the antimicrobial activity of a...given substance are done in physiological buffer (with the exception of many antibiotics as these require active metabolism for efficacy). This can be

Performance of Selected Fabrics on the Decontaminable Litter and Litter Mattress to Correct a Problem of Unexpected Sliding during Patient Loading on a C-9 (Nightingale) Aircraft.

DTIC Science & Technology

1992-01-30

Chemical Agent Resistant Coating, retractable nylon handles, ethylene propylenediene monomer ( EPDM ) rubber securing straps, and a woven monofilament...Polypropylene Honeycomb 19 Saran Honeycomb 22 4. Mattress fabric: 5laobcbe 29!, 10.6 oz/sq yd, Source: Herculite Products, Inc., York, PA UI r Q r W&de k ( Ag

Effectiveness of Vaporous Hydrogen Peroxide for the Decontamination of Representative Military Materials

DTIC Science & Technology

2004-11-16

Agent Resistant Coating (CARC) Geobacillus stearothermophilus ATCC 7953 Flott Glass Galvanized aluminum Polyimid (Kapton) Nylon Webbing Runway...spores were harvested from 7-10 day –old cultures plated upon Lemko Agar. The spores were washed thrice in sterile distilled water (dH2O), and...NEGATIVE SURROGATE Inocula of log-phase Y. ruckeri were prepared immediately before application to sterile coupons. Cells were grown in nutrient

Life Cycle Assessment for Chemical Agent Resistant Coating.

DTIC Science & Technology

1996-09-01

994) document to develop HVs from 1 to 2.5. The final equivalency factor for a chemical was based on the formula: Equivalency Factor = (toxicity HV...applicable to the development of processes/procedures and their implementation, likely would fit better with a true LCA- based design exercise for a product...Johnny Springer, Jr., National Risk Management Research Laboratory, Office of Research and Development , U.S. Environmental Protection Agency

A nanometallic nickel-coated, glass-fibre-based structural health monitoring system for polymer composites

NASA Astrophysics Data System (ADS)

Balaji, R.; Sasikumar, M.

2017-09-01

Glass-fibre-reinforced polymer matrix composites are widely used in various industries because of their unique high strength to weight ratio. Unlike metals, strain-induced and damage states of composites are complicated to predict under real-time loading due to their anisotropic nature. With that focus, a piezoresistive nanomaterial-based structural health monitoring system for laminated polymer composites is proposed to measure the strain induced in the composite under real-time loading. Nanometallic nickel-coated glass fibres are embedded into the polymer composites to monitor the strain and damage induced in them. The nanometallic nickel is coated over the glass fibre by a dip coating technique using epoxy as the binding agent. A microcontroller-based electrical resistance measurement system is used to measure the piezoresistive variation in the coated glass fibre under real-time loading. Using the piezoresistance variation of the embedded nanometallic nickel-coated glass fibre, the real-time strain and damage induced in the composite can be correlated. The piezoresistive response of the coated glass fibre is descibed in two phases, the deformation phase and the failure phase, which clearly show the various states of strain and damage induced in the composites.

Research with Large Area Imaging X-Ray Telescope Sounding Rocket Program

NASA Technical Reports Server (NTRS)

Gorenstein, Paul

1999-01-01

We are engaged in a program to develop focussing hard X-ray telescopes in a double conical or Wolter 1 geometry that function up to 100 keV by employing small graze angles and multilayer coatings. Directly polished substrates are not an option because they are too thick to be nested efficiently. The only alternative is to fabricate the very thin substrates by replication. Our objective is the production of integral cylindrical substrates because they should result in better angular resolution than segmented foil geometries. In addition, integral cylinders would be more resistant to possible stress from deep multilayer coatings than segmented ones. Both electroforming of nickel (method of SkX, JET-X, and XMM) and epoxy replication are under consideration. Both processes can utilize the same types of mandrels and separation agents- While electroforming can produce substrates that are thin, the high density of the nickel may result in high weight optics for some missions. For convenience, experimentation with replication and coating is being carried out initially on flats. Our replication studies include trials with gold and carbon separation agents. This paper reports on our efforts with epoxy replicated optics.

Reduced Zeta potential through use of cationic adhesion promoter for improved resist process performance and minimizing material consumption

NASA Astrophysics Data System (ADS)

Hodgson, Lorna; Thompson, Andrew

2012-03-01

This paper presents the results of a non-HMDS (non-silane) adhesion promoter that was used to reduce the zeta potential for very thin (proprietary) polymer on silicon. By reducing the zeta potential, as measured by the minimum sample required to fully coat a wafer, the amount of polymer required to coat silicon substrates was significantly reduced in the manufacture of X-ray windows used for high transmission of low-energy X-rays. Moreover, this approach used aqueous based adhesion promoter described as a cationic surface active agent that has been shown to improve adhesion of photoresists (positive, negative, epoxy [SU8], e-beam and dry film). As well as reducing the amount of polymer required to coat substrates, this aqueous adhesion promoter is nonhazardous, and contains non-volatile solvents.

The hazardous hexavalent chromium formed on trivalent chromium conversion coating: The origin, influence factors and control measures.

PubMed

Li, Jinhua; Yao, Chenlan; Liu, Yanbiao; Li, Di; Zhou, Baoxue; Cai, Weimin

2012-06-30

In this paper, the effects of processing parameters and constituents of treating-agent on the presence of hazardous hexavalent chromium on trivalent chromium conversion coating were studied. Results showed that shorter immersion time, lower bath pH value as well as lower working and baking temperatures retarded the presence of hexavalent chromium. In addition, the concentration of hexavalent chromium on conversion coatings prepared by the oxalic acid treating-agent was far greater than those on conversion coatings prepared by formic acid and acetic acid treating-agents. Results also indicated that the concentration of hexavalent chromium on conversion coatings was enhanced due to the addition of bivalent cobalt and nitrate anion in treating-agent, especially for oxalic acid conversion coating. However, the addition of hydroxyl compound d-gluconic acid in treating-agent could reduce the concentration of hexavalent chromium effectively. Moreover, a possible formation mechanism of hexavalent chromium on trivalent conversion coating was proposed. Findings of this study provide a better understanding of the formation of hexavalent chromium on trivalent chromium conversion coating and can facilitate the management of trivalent chromium treating-agents and trivalent chromium fasteners. Copyright © 2012 Elsevier B.V. All rights reserved.

Electrical Resistivity of Wire Arc Sprayed Zn and Cu Coatings for In-Mold-Metal-Spraying

NASA Astrophysics Data System (ADS)

Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Hopmann, Ch; Ochotta, P.

2018-06-01

Electrical functionalities can be integrated into plastic parts by integrating thermally sprayed metal coatings into the non-conductive base material. Thermally sprayed conducting tracks for power and signal transmission are one example. In this case, the electrical resistance or resistivity of the coatings should be investigated. Therefore, the electrical resistivity of wire arc sprayed Zn and Cu coatings has been investigated. In case of Zn coatings, spray distance, gas pressure and wire diameter could be identified as significant influencing parameters on the electrical resistivity. In contrast, process gas, gas pressure and voltage do have a significant influence on the electrical resistivity of Cu coatings. Through the use of the In-Mold-Metal-Spraying method (IMMS), thermal degradation can be avoided by transferring thermally sprayed coating from a mold insert onto the plastic part. Therefore, the influence of the transfer process on the electrical resistance of the coatings has also been investigated.

Influence of citric acid on the surface texture of glass ionomer restorative materials

PubMed Central

Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

2014-01-01

Aim: This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Materials and Methods: Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, μm) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. Results: The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. Conclusion: The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative materials. PMID:25298643

Influence of citric acid on the surface texture of glass ionomer restorative materials.

PubMed

Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

2014-09-01

This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, μm) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative materials.

Erosion-resistant coatings for gas turbine engine compressor blades

NASA Astrophysics Data System (ADS)

Kablov, E. N.; Muboyadzhyan, S. A.

2017-06-01

The erosion-resistant ZrN and Cr3C2 coatings intended for the protection of the titanium and steel blades in a GTE compressor are studied. The erosion resistance of the substrate-coating composition is shown to depend on the coating thickness, the deposition conditions, and the coating texture. Ion-assisted deposition changes the structure-phase state of a coating and substantially increases its erosion resistance. It is found that a nanolayer 2D TiN/CrN coating with an average nanolayer thickness of 60 nm is the best erosion- corrosion-resistant coating for titanium alloys and that a (NiCrTiAlHf)C + CrC coating formed by ionassisted deposition is the best coating for steels. The testing of alloy VT8 compressor blades in an engine supported high protective properties of the nanolayer TiN/CrN coating.

Polymeric nanofiber coating with tunable combinatorial antibiotic delivery prevents biofilm-associated infection in vivo

PubMed Central

Ashbaugh, Alyssa G.; Jiang, Xuesong; Zheng, Jesse; Tsai, Andrew S.; Kim, Woo-Shin; Thompson, John M.; Miller, Robert J.; Shahbazian, Jonathan H.; Wang, Yu; Dillen, Carly A.; Ordonez, Alvaro A.; Chang, Yong S.; Jain, Sanjay K.; Jones, Lynne C.; Sterling, Robert S.; Mao, Hai-Quan; Miller, Lloyd S.

2016-01-01

Bacterial biofilm formation is a major complication of implantable medical devices that results in therapeutically challenging chronic infections, especially in cases involving antibiotic-resistant bacteria. As an approach to prevent these infections, an electrospun composite coating comprised of poly(lactic-coglycolic acid) (PLGA) nanofibers embedded in a poly(ε-caprolactone) (PCL) film was developed to locally codeliver combinatorial antibiotics from the implant surface. The release of each antibiotic could be adjusted by loading each drug into the different polymers or by varying PLGA:PCL polymer ratios. In a mouse model of biofilm-associated orthopedic-implant infection, three different combinations of antibiotic-loaded coatings were highly effective in preventing infection of the bone/joint tissue and implant biofilm formation and were biocompatible with enhanced osseointegration. This nanofiber composite-coating technology could be used to tailor the delivery of combinatorial antimicrobial agents from various metallic implantable devices or prostheses to effectively decrease biofilm-associated infections in patients. PMID:27791154

Active corrosion protection performance of an epoxy coating applied on the mild steel modified with an eco-friendly sol-gel film impregnated with green corrosion inhibitor loaded nanocontainers

NASA Astrophysics Data System (ADS)

Izadi, M.; Shahrabi, T.; Ramezanzadeh, B.

2018-05-01

In this study the corrosion resistance, active protection, and cathodic disbonding performance of an epoxy coating were improved through surface modification of steel by a hybrid sol-gel system filled with green corrosion inhibitors loaded nanocontainer as intermediate layer on mild steel substrate. The green inhibitor loaded nanocontainers (GIN) were used to induce active inhibition performance in the protective coating system. The corrosion protection performance of the coated panels was investigated by electrochemical impedance spectroscopy (EIS), salt spray, and cathodic disbonding tests. It was observed that the corrosion inhibition performance of the coated mild steel panels was significantly improved by utilization of active multilayer coating system. The inhibitor release from nanocontainers at the epoxy-silane film/steel interface resulted in the anodic and cathodic reactions restriction, leading to the lower coating delamination from the substrate and corrosion products progress. Also, the active inhibition performance of the coating system was approved by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDS) analysis on the panels with artificial defects. The inhibitive agents were released to the scratch region and blocked the active sites on the metal surface.

Structure, apatite inducing ability, and corrosion behavior of chitosan/halloysite nanotube coatings prepared by electrophoretic deposition on titanium substrate.

PubMed

Molaei, A; Amadeh, A; Yari, M; Reza Afshar, M

2016-02-01

In this study chitosan/halloysite nanotube composite (CS/HNT) coatings were deposited by electrophoretic deposition (EPD) on titanium substrate. Using HNT particles were investigated as new substituents for carbon nanotubes (CNTs) in chitosan matrix coatings. The ability of chitosan as a stabilizing, charging, and blending agent for HNT particles was exploited. Furthermore, the effects of pH, electrophoretic bath, and sonicating duration were studied on the deposition of suspensions containing HNT particles. Microstructure properties of coatings showed uniform distribution of HNT particles in chitosan matrix to form smooth nanocomposite coatings. The zeta potential results revealed that at pH around 3 there is an isoelectric point for HNT and it would have cathodic and anionic states at pH values less and more than 3, respectively. Therefore, CS/HNT composite deposits were produced in the pH range of 2.5 to 3. The apatite inducing ability of chitosan-HNT composite coating assigned that HNT particles were biocompatible because they formed carbonated hydroxyapatite particles on CS/HNT coating in corrected simulated body fluid (C-SBF). Finally, electrochemical corrosion characterizations determined that corrosion resistance in CS/HNT coating has been improved compared to bare titanium substrate. Copyright © 2015 Elsevier B.V. All rights reserved.

Titanium dioxide antireflection coating for silicon solar cells by spray deposition

NASA Technical Reports Server (NTRS)

Kern, W.; Tracy, E.

1980-01-01

A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

Reduced bacteria adhesion on octenidine loaded mesoporous silica nanoparticles coating on titanium substrates.

PubMed

Xu, Gaoqiang; Shen, Xinkun; Dai, Liangliang; Ran, Qichun; Ma, Pingping; Cai, Kaiyong

2017-01-01

Bacterial infection is one of the most severe postoperative complications leading to implantation failure. The early bacterial stage (4-6h) was proved to be the "decisive period" for long-term bacteria-related infection. Thus, to endow potential early antibacterial capacity for a titanium (Ti) based implant, an effective antiseptic agent of octenidine dihydrochloride (OCT) was effectively loaded on the mesoporous silica nanoparticles (MSNs)-incorporated titania coating which was fabricated by an electrophoretic-enhanced micro-arc oxidation technique. The surface characteristic of the coatings were characterized by various methods (SEM, AFM, XPS, XRD, etc.), and its corrosion resistance was also examined by the potentiodynamic polarization curves. The composite coating without OCT loading not only displayed good cytocompatibility but also exhibited certain anti-bacterial property. After loading with OCT, its antibacterial efficiency of the titanium substrates with composite coating was greatly enhanced without compromising their cytocompatibility. The study provides an approach for the fabrication of anti-bacterial Ti implant for potential orthopedic application. Copyright © 2016 Elsevier B.V. All rights reserved.

Acoustic Characterization and Enhanced Ultrasound Imaging of Long-Circulating Lipid-Coated Microbubbles.

PubMed

Li, Hongbo; Yang, Yanye; Zhang, Meimei; Yin, Liping; Tu, Juan; Guo, Xiasheng; Zhang, Dong

2018-05-01

A long-circulating lipid-coated ultrasound (US) contrast agent was fabricated to achieve a longer wash-out time and gain more resistance against higher-mechanical index sonication. Systemic physical, acoustic, and in vivo imaging experiments were performed to better understand the underlying mechanism enabling the improvement of contrast agent performance by adjusting the physical and acoustic properties of contrast agent microbubbles. By simply altering the gas core, a kind of US contrast agent microbubble was synthesized with a similar lipid-coating shell as SonoVue microbubbles (Bracco SpA, Milan, Italy) to achieve a longer wash-out time and higher inertial cavitation threshold. To bridge the structure-performance relationship of the synthesized microbubbles, the imaging performance of the microbubbles was assessed in vivo with SonoVue as a control group. The size distribution and inertial cavitation threshold of the synthesized microbubbles were characterized, and the shell parameters of the microbubbles were determined by acoustic attenuation measurements. All of the measurements were compared with SonoVue microbubbles. The synthesized microbubbles had a spherical shape, a smooth, consistent membrane, and a uniform distribution, with an average diameter of 1.484 μm. According to the measured attenuation curve, the synthesized microbubbles resonated at around 2.8 MHz. Although the bubble's shell elasticity (0.2 ± 0.09 N/m) was comparable with SonoVue, it had relatively greater viscosity and inertial cavitation because of the different gas core. Imaging studies showed that the synthesized microbubbles had a longer circulation time and a better chance of fighting against rapid collapse than SonoVue. Nano/micrometer long-circulating lipid-coated microbubbles could be fabricated by simply altering the core composition of SonoVue microbubbles with a higher-molecular weight gas. The smaller diameter and higher inertial cavitation threshold of the synthesized microbubbles might make it easier to access deep-seated organs and give prolonged imaging enhancement in the liver. © 2017 by the American Institute of Ultrasound in Medicine.

Polydopamine-coated capsules

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, Scott R.; Sottos, Nancy R.; Kang, Sen

One aspect of the invention is a polymer material comprising a capsule coated with PDA. In certain embodiments, the capsule encapsulates a functional agent. The encapsulated functional agent may be an indicating agent, healing agent, protecting agent, pharmaceutical drug, food additive, or a combination thereof.

Phenol-formaldehyde intumescent coating composition and coating prepared therefrom

NASA Technical Reports Server (NTRS)

Salyer, Ival O. (Inventor); Fox, Bernard L. (Inventor)

1986-01-01

Intumescent coatings which form a thick, uniform, fine celled, low density foam upon exposure to a high intensity heat flux or flame are disclosed, the invention coatings comprise phenolic resin prepolymer containing a blowing agent and a nucleating agent; in the preferred embodiments the coatings also contains a silicone surfactant, the coatings are useful in thermal and fire protection systems.

Solventless visible light-curable coating: I. Critical formulation and processing parameters.

PubMed

Bose, Sagarika; Bogner, Robin H

2010-06-30

Film coating is generally accomplished by spraying polymers dissolved in solvents onto a cascading bed of tablets. The limitations associated with the use of solvents (both aqueous and organic) can be overcome by the use of solventless coating technologies. In this proposed solventless photocurable film coating system, each layer of coating onto the pellets (non-pareil beads) was formed using liquid photocurable monomer, powdered pore-forming agents, photosensitizers and photoinitiators in a mini-coating pan and later cured by visible light. Yield, coating efficiency, variation in color, diameter and roundness were determined for each batch to evaluate process efficiency and coating quality. It was found that the ratio (S/L ratio) of the amount of solid (S) pore-forming agent to volume of liquid (L) monomer, particle size and type of the pore-forming agent, concentration of initiator, and total exposure (light intensity x exposure time) of light were critical formulation and processing parameters for the process. Using lactose as a pore-forming agent, an optimum ratio of pore-forming agent to photocurable polymer was 1.8-3.0 to achieve good process efficiency and uniformity. The ratio was sensitive to particle size and type of pore-forming agent. 2010 Elsevier B.V. All rights reserved.

Antibody-directed targeting of lysostaphin adsorbed onto polylactide nanoparticles increases its antimicrobial activity against S. aureus in vitro

NASA Astrophysics Data System (ADS)

Satishkumar, R.; Vertegel, A. A.

2011-12-01

The objective of this paper was to study the effect of antibody-directed targeting of S. aureus by comparing the activities of lysostaphin conjugated to biodegradable polylactide nanoparticles (NPs) in the presence and in the absence of co-immobilized anti-S. aureus antibody. Lysostaphin-antibody-NP conjugates were synthesized through physical adsorption at different enzyme:antibody:NP ratios. The synthesized enzyme-NP conjugates were characterized by means of dynamic light scattering and zeta potential analysis, and the total protein binding yield on the NPs was characterized using Alexa Fluor 350 and 594 dyes for the S. aureus antibody and lysostaphin respectively. We observed enhanced antimicrobial activity for both enzyme-coated and enzyme-antibody-coated NPs for lysostaphin coatings corresponding to ~ 40% of the initial monolayer and higher compared to the free enzyme case (p < 0.05). At the highest antibody coating concentration, bacterial lysis rates for antibody-coated samples were significantly higher than for lysostaphin-coated samples lacking the antibody (p < 0.05). Such enzyme-NP conjugates thus have the potential for becoming novel therapeutic agents for treating antibiotic-resistant S. aureus infections.

Antimicrobial activity of transition metal acid MoO(3) prevents microbial growth on material surfaces.

PubMed

Zollfrank, Cordt; Gutbrod, Kai; Wechsler, Peter; Guggenbichler, Josef Peter

2012-01-01

Serious infectious complications of patients in healthcare settings are often transmitted by materials and devices colonised by microorganisms (nosocomial infections). Current strategies to generate material surfaces with an antimicrobial activity suffer from the consumption of the antimicrobial agent and emerging multidrug-resistant pathogens amongst others. Consequently, materials surfaces exhibiting a permanent antimicrobial activity without the risk of generating resistant microorganisms are desirable. This publication reports on the extraordinary efficient antimicrobial properties of transition metal acids such as molybdic acid (H(2)MoO(4)), which is based on molybdenum trioxide (MoO(3)). The modification of various materials (e.g. polymers, metals) with MoO(3) particles or sol-gel derived coatings showed that the modified materials surfaces were practically free of microorganisms six hours after contamination with infectious agents. The antimicrobial activity is based on the formation of an acidic surface deteriorating cell growth and proliferation. The application of transition metal acids as antimicrobial surface agents is an innovative approach to prevent the dissemination of microorganisms in healthcare units and public environments. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of Moisture-Cure Urethane Coatings for Compliance with Industry Specifications

DTIC Science & Technology

2011-12-01

Upon curing, RUST GRIP provides a protective coating of superior adhesion, flexibility, abrasion - and impact- resistance . It is resistant to most...THANE 2821 is an extremely hard abrasion resistant coating. It is ideally suited for usage such as bridges, tanks, locks and dams, marine structures...extremely hard abrasion resistant coating. It makes an excellent coating for concrete floors when used directly on concrete. CHEM-THANE 2822HS

Fabrication of 10 μm-scale conductive Cu patterns by selective laser sintering of Cu complex ink

NASA Astrophysics Data System (ADS)

Min, Hyungsuk; Lee, Byoungyoon; Jeong, Sooncheol; Lee, Myeongkyu

2017-02-01

A Cu complex ink was synthesized using copper formate as a precursor and its potential for laser patterning was investigated. The Cu ink was spin-coated onto a substrate and the coated film was space-selectively sintered using a nanosecond-pulsed ultraviolet laser. The unexposed Cu ink could be removed from the film by rinsing it with the dispersing agent used to synthesize the ink, disclosing a conductive Cu pattern. A minimum resistivity of 8.46×10-5 Ω cm was obtained for the Cu lines with 10-20 μm widths. The feasibility of this method for metallization was demonstrated by fabricating a complex Cu electric circuit on an indium tin oxide-coated glass substrate. The selective laser sintering approach provides a simple, cost-effective alternative to conventional lithography for the production of electrode or metallization patterns.

Fluorescent ampicillin analogues as multifunctional disguising agents against opsonization

NASA Astrophysics Data System (ADS)

Kotagiri, Nalinikanth; Sakon, Joshua; Han, Haewook; Zharov, Vladimir P.; Kim, Jin-Woo

2016-06-01

Cancer nanomedicines are opening new paradigms in cancer management and recent research points to how they can vastly improve imaging and therapy through multimodality and multifunctionality. However, challenges to achieving optimal efficacy are manifold starting from processing materials and evaluating their intended effectiveness on biological tissue, to developing new strategies aimed at improving transport of these materials through the biological milieu to the target tissue. Here, we report a fluorescent derivative of a beta-lactam antibiotic, ampicillin (termed iAmp) and its multifunctional physicobiochemical characteristics and potential as a biocompatible shielding agent and an effective dispersant. Carbon nanotubes (CNTs) were chosen to demonstrate the efficacy of iAmp. CNTs are known for their versatility and have been used extensively for cancer theranostics as photothermal and photoacoustic agents, but have limited solubility in water and biocompatibility. Traditional dispersants are associated with imaging artifacts and are not fully biocompatible. The chemical structure of iAmp is consistent with a deamination product of ampicillin. Although the four-membered lactam ring is intact, it does not retain the antibiotic properties. The iAmp is an effective dispersant and simultaneously serves as a fluorescent label for single-walled CNTs (SWNTs) with minimal photobleaching. The iAmp also enables bioconjugation of SWNTs to bio-ligands such as antibodies through functional carboxyl groups. Viability tests show that iAmp-coated SWNTs have minimal toxicity. Bio-stability tests under physiological conditions reveal that iAmp coating not only remains stable in a biologically relevant environment with high protein and salt concentrations, but also renders SWNTs transparent against nonspecific protein adsorption, also known as protein corona. Mammalian tissue culture studies with macrophages and opsonins validate that iAmp coating affords immunological resistance to SWNTs. Furthermore, iAmp coating offers protection to SWNTs against their nonspecific adsorption across disparate cell types, which has precluded a targeted strategy, and enables selective molecular targeting. The iAmp can therefore be used as an efficient dispersant, a photostable fluorescent agent, and a biocompatible disguising agent, alleviating CNTs' drawbacks and rendering them suitable for nanotheranostic and drug delivery applications.Cancer nanomedicines are opening new paradigms in cancer management and recent research points to how they can vastly improve imaging and therapy through multimodality and multifunctionality. However, challenges to achieving optimal efficacy are manifold starting from processing materials and evaluating their intended effectiveness on biological tissue, to developing new strategies aimed at improving transport of these materials through the biological milieu to the target tissue. Here, we report a fluorescent derivative of a beta-lactam antibiotic, ampicillin (termed iAmp) and its multifunctional physicobiochemical characteristics and potential as a biocompatible shielding agent and an effective dispersant. Carbon nanotubes (CNTs) were chosen to demonstrate the efficacy of iAmp. CNTs are known for their versatility and have been used extensively for cancer theranostics as photothermal and photoacoustic agents, but have limited solubility in water and biocompatibility. Traditional dispersants are associated with imaging artifacts and are not fully biocompatible. The chemical structure of iAmp is consistent with a deamination product of ampicillin. Although the four-membered lactam ring is intact, it does not retain the antibiotic properties. The iAmp is an effective dispersant and simultaneously serves as a fluorescent label for single-walled CNTs (SWNTs) with minimal photobleaching. The iAmp also enables bioconjugation of SWNTs to bio-ligands such as antibodies through functional carboxyl groups. Viability tests show that iAmp-coated SWNTs have minimal toxicity. Bio-stability tests under physiological conditions reveal that iAmp coating not only remains stable in a biologically relevant environment with high protein and salt concentrations, but also renders SWNTs transparent against nonspecific protein adsorption, also known as protein corona. Mammalian tissue culture studies with macrophages and opsonins validate that iAmp coating affords immunological resistance to SWNTs. Furthermore, iAmp coating offers protection to SWNTs against their nonspecific adsorption across disparate cell types, which has precluded a targeted strategy, and enables selective molecular targeting. The iAmp can therefore be used as an efficient dispersant, a photostable fluorescent agent, and a biocompatible disguising agent, alleviating CNTs' drawbacks and rendering them suitable for nanotheranostic and drug delivery applications. Electronic supplementary information (ESI) available: Details of quantum yield estimation and physicobiochemical analyses to assess the mechanism of iAmp synthesis and its chemical structure as well as the cytotoxicity and bio-stability of iAmp and iAmp-SWNT hybrids. See DOI: 10.1039/c5nr08686h

Anti-microbial coating innovations to prevent infectious diseases (AMiCI): Cost action ca15114

PubMed Central

Dunne, Colum P.; Kahru, Anne; Teunissen, Birgit; Gouveia, Isabel; Murzyn, Kazimierz; Modic, Martina; Askew, Pete; Papadopoulos, Theofilos

2017-01-01

ABSTRACT Worldwide, millions of patients are affected annually by healthcare-associated infection (HCAI), impacting up to 80,000 patients in European Hospitals on any given day. This represents not only public health risk, but also an economic burden. Complementing routine hand hygiene practices, cleaning and disinfection, antimicrobial coatings hold promise based, in essence, on the application of materials and chemicals with persistent bactericidal or –static properties onto surfaces or in textiles used in healthcare environments. The focus of considerable commercial investment and academic research energies, such antimicrobial coating-based approaches are widely believed to have potential in reduction of microbial numbers on surfaces in clinical settings. This belief exists despite definitive evidence as to their efficacy and is based somewhat on positive studies involving, for example, copper, silver or gold ions, titanium or organosilane, albeit under laboratory conditions. The literature describes successful delay and/or prevention of recontamination following conventional cleaning and disinfection by problematic microbes such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), among others. However, there is a scarcity of studies assessing antimicrobial surfaces other than copper in the clinical environment, and a complete lack of published data regarding the successful implementation of these materials on clinically significant outcomes (including HCAI). Through its Cooperation in Science and Technology program (COST), the European Commission has funded a 4-year initiative to establish a network of stakeholders involved in development, regulation and use of novel anti-microbial coatings for prevention of HCAI. The network (AMiCI) comprises participants of more than 60 universities, research institutes and companies across 29 European countries and, to-date, represents the most comprehensive consortium targeting use of these emergent technologies in healthcare settings. More specifically, the network will prioritise coordinated research on the effects (both positive and negative) of antimicrobial coatings in healthcare sectors; know-how regarding availability and mechanisms of action of (nano)-coatings; possible adverse effects of such materials (e.g., potential emergence of microbial resistance or emission of toxic agents into the environment); standardised performance assessments for antimicrobial coatings; identification and dissemination of best practices by hospitals, other clinical facilities, regulators and manufacturers. PMID:28453429

Anti-microbial coating innovations to prevent infectious diseases (AMiCI): Cost action ca15114.

PubMed

Dunne, Colum P; Keinänen-Toivola, Minna M; Kahru, Anne; Teunissen, Birgit; Olmez, Hulya; Gouveia, Isabel; Melo, Luis; Murzyn, Kazimierz; Modic, Martina; Ahonen, Merja; Askew, Pete; Papadopoulos, Theofilos; Adlhart, Christian; Crijns, Francy R L

2017-11-02

Worldwide, millions of patients are affected annually by healthcare-associated infection (HCAI), impacting up to 80,000 patients in European Hospitals on any given day. This represents not only public health risk, but also an economic burden. Complementing routine hand hygiene practices, cleaning and disinfection, antimicrobial coatings hold promise based, in essence, on the application of materials and chemicals with persistent bactericidal or -static properties onto surfaces or in textiles used in healthcare environments. The focus of considerable commercial investment and academic research energies, such antimicrobial coating-based approaches are widely believed to have potential in reduction of microbial numbers on surfaces in clinical settings. This belief exists despite definitive evidence as to their efficacy and is based somewhat on positive studies involving, for example, copper, silver or gold ions, titanium or organosilane, albeit under laboratory conditions. The literature describes successful delay and/or prevention of recontamination following conventional cleaning and disinfection by problematic microbes such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), among others. However, there is a scarcity of studies assessing antimicrobial surfaces other than copper in the clinical environment, and a complete lack of published data regarding the successful implementation of these materials on clinically significant outcomes (including HCAI). Through its Cooperation in Science and Technology program (COST), the European Commission has funded a 4-year initiative to establish a network of stakeholders involved in development, regulation and use of novel anti-microbial coatings for prevention of HCAI. The network (AMiCI) comprises participants of more than 60 universities, research institutes and companies across 29 European countries and, to-date, represents the most comprehensive consortium targeting use of these emergent technologies in healthcare settings. More specifically, the network will prioritise coordinated research on the effects (both positive and negative) of antimicrobial coatings in healthcare sectors; know-how regarding availability and mechanisms of action of (nano)-coatings; possible adverse effects of such materials (e.g., potential emergence of microbial resistance or emission of toxic agents into the environment); standardised performance assessments for antimicrobial coatings; identification and dissemination of best practices by hospitals, other clinical facilities, regulators and manufacturers.

Towards lightweight nanocomposite coatings for corrosion inhibition: Graphene, carbon nanotubes, and nanostructured magnesium as case studies

NASA Astrophysics Data System (ADS)

Dennis, Robert Vincent, III

The field of nanocomposites is a burgeoning area of research due to the interest in the remarkable properties which can be achieved through their use in a variety of applications, including corrosion resistant coatings. Lightweighting is of increasing importance in the world today due to the ever growing push towards energy efficiency and the green movement and in recent years there has been a vast amount of research performed in the area of developing lightweight nanocomposites for corrosion inhibition. Many new composite materials have been developed through the use of newly developed nanomaterials (including carbonaceous and metallic constituents) and their specialized incorporation in the coating matrix materials. We start with a general review on the development of hybrid nanostructured composites for corrosion protection of base metals from a sustainability perspective in Chapter 1. This review demonstrates the ever swelling requirements for a paradigm shift in the way that we protect metals against corrosion due to the costs and environmental concerns that exist with currently used technology. In Chapter 2, we delve into the much required understanding of graphene oxide and reduced graphene oxide through near-edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements to elucidate information about the electronic structure upon incorporation of nitrogen within the structure. For successful integration of the carbonaceous nanomaterials into a composite coating, a full swath of knowledge is necessary. Within this work we have shown that upon chemical defunctionalization of graphene oxide to reduced graphene oxide by means of hydrazine treatment, nitrogen is incorporated into the structure in the form of a pyrazole ring. In Chapter 3, we demonstrate that by way of in situ polymerization, graphene and multiwalled carbon nanotubes can be incorporated within a polymer (polyetherimide, PEI) matrix. Two systems have been developed including graphene and multiwalled carbon nanotubes that act synergistically at a concentration of 2 wt.% each along with graphene at 20 wt.%. The in situ polymerization technique allows for well dispersed carbon nanomaterials within the polymer matrix, which is always a necessary requirement for success as a multifunctional composite coating. After testing in harsh corrosive brine environments these coatings outperformed the polymer by itself and even Zn galvanized steel, lowering the estimated corrosion rate by several orders of magnitude. Chapter 4 displays the possible uses of functionalized carbon nanomaterials in the design of a nanocomposite for corrosion resistance. In this work we establish a method of crosslinking and curing of the polymer matrix using the carbon nanofiller materials as a curing agent through the knowledge partially developed from work outlined in Chapter 2. Here we have used the native functional groups (hydroxyls and carboxylic acids) on graphene oxide and oxidized multiwalled carbon nanotubes to initiate the curing reaction with a well-known commercially available and commonly used epoxy resin. This technology allows for the chemical integration of the nanofiller within the polymer matrix, ensuring excellent dispersion, and also removing the need for often toxic curing agents. The nanocomposites created here have also been tested for their corrosion resistant properties. Concluding with Chapter 5, we exploit some of our previous work on the development of nanostructured magnesium for use in corrosion resistant coatings based on Mg-rich primer technology. It was shown that Mg nanoplatelets allow for a much increased surface area for interaction with the polymer matrix, leading to excellent property enhancement at a significantly reduced pigment volume concentration and coating thickness. These enhancements lead to less material being used, lighter/thinner coatings, and improved performance. These nano Mg-rich primer formulations were shown to protect the underlying steel substrates from corrosion upon breakdown, in the form of a scratch to the metal surface, of the coating; preferentially oxidizing before the iron in steel. The coatings also were found to reduce the corrosion rate by up to 4 orders of magnitude.

Evaluation of Erosion Resistance of Advanced Turbine Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Kuczmarski, Maria A.; Miller, Robert A.; Cuy, Michael D.

2007-01-01

The erosion resistant turbine thermal barrier coating system is critical to aircraft engine performance and durability. By demonstrating advanced turbine material testing capabilities, we will be able to facilitate the critical turbine coating and subcomponent development and help establish advanced erosion-resistant turbine airfoil thermal barrier coatings design tools. The objective of this work is to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and/or thermal gradient environments, validating advanced turbine airfoil thermal barrier coating systems based on nano-tetragonal phase toughening design approaches.

Low Temperature Cure Powder Coatings (LTCPC)

DTIC Science & Technology

2010-10-01

17  3.2.2.5  Abrasion Resistance ...criteria • N/A Field Service Evaluation: • Coating Appearance • Adhesion • Fluids Resistance • Humidity Resistance • Abrasion Resistance • Low...Results • Abrasion Resistance • Low Temperature Flexibility humidity • Document occurrences of coating abrasions during

Efficiency of vanilla, patchouli and ylang ylang essential oils stabilized by iron oxide@C14 nanostructures against bacterial adherence and biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae clinical strains.

PubMed

Bilcu, Maxim; Grumezescu, Alexandru Mihai; Oprea, Alexandra Elena; Popescu, Roxana Cristina; Mogoșanu, George Dan; Hristu, Radu; Stanciu, George A; Mihailescu, Dan Florin; Lazar, Veronica; Bezirtzoglou, Eugenia; Chifiriuc, Mariana Carmen

2014-11-04

Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14) in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h) and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

Top coat or no top coat for immersion lithography?

NASA Astrophysics Data System (ADS)

Stepanenko, N.; Kim, Hyun-Woo; Kishimura, S.; Van Den Heuvel, D.; Vandenbroeck, N.; Kocsis, M.; Foubert, P.; Maenhoudt, M.; Ercken, M.; Van Roey, F.; Gronheid, R.; Pollentier, I.; Vangoidsenhoven, D.; Delvaux, C.; Baerts, C.; O'Brien, S.; Fyen, W.; Wells, G.

2006-03-01

Since the moment immersion lithography appeared in the roadmaps of IC manufacturers, the question whether to use top coats has become one of the important topics for discussions. The top coats used in immersion lithography have proved to serve as good protectors from leaching of the resist components (PAGs, bases) into the water. However their application complicates the process and may lead to two side effects. First, top coats can affect the process window and resist profile depending on the material's refractive index, thickness, acidity, chemical interaction with the resist and the soaking time. Second, the top coat application may increase the total amount of defects on the wafer. Having an immersion resist which could work without the top coat would be a preferable solution. Still, it is quite challenging to make such a resist as direct water/resist interaction may also result in process window changes, CD variations, generation of additional defects. We have performed a systematic evaluation of a large number of immersion resist and top coat combinations, using the ASML XT:1250Di scanner at IMEC. The samples for the experiments were provided by all the leading resist and top coat suppliers. Particular attention was paid to how the resist and top coat materials from different vendors interacted with each other. Among the factors which could influence the total amount of defects or CD variations on the wafer were: the material's dynamic contact angle and its interaction with the scanner stage speed, top coat thickness and intermixing layer formation, water uptake and leaching. We have examined the importance of all mentioned factors, using such analytical techniques as Resist Development Analyser (RDA), Quartz Crystal Microbalance (QCM), Mass Spectroscopy (MS) and scatterometry. We have also evaluated the influence of the pre- and pos- exposure rinse processes on the defectivity. In this paper we will present the data on imaging and defectivity performance of the resists with and without the use of top coats. So far we can conclude that top coat/resist approach used in immersion lithography needs some more improvements (i.e. process, materials properties) in order to be implemented in high volume manufacturing.

Chemistry and stability of thiol based polyethylene glycol surface coatings on colloidal gold and their relationship to protein adsorption and clearance in vivo

NASA Astrophysics Data System (ADS)

Carpinone, Paul

Nanomaterials have presented a wide range of novel biomedical applications, with particular emphasis placed on advances in imaging and treatment delivery. Of the many particulate nanomaterials researched for biomedical applications, gold is one of the most widely used. Colloidal gold has been of great interest due to its chemical inertness and its ability to perform multiple functions, such as drug delivery, localized heating of tissues (hyperthermia), and imaging (as a contrast agent). It is also readily functionalized through the use of thiols, which spontaneously form sulfur to gold bonds with the surface. Polyethylene glycol (PEG) is the most widely used coating material for these particles as it provides both steric stability to the suspension and protein resistance. These properties extend the circulation time of the particles in blood, and consequently the efficacy of the treatment. Despite widespread use of PEG coated gold particles, the coating chemistry and stability of these particles are largely unknown. The goal of this work was to identify the mechanisms leading to degradation and stability of thiol based polyethylene glycol coatings on gold particles and to relate this behavior to protein adsorption and clearance in vivo. The results indicate that the protective PEG coating is susceptible to sources of oxidation (including dissolved oxygen) and competing adsorbates, among other factors. The quality of commercially available thiolated PEG reagents was also found to play a key role in the quality and protein resistance of the final PEG coating. Analysis of the stability of these coatings indicated that they rapidly degrade under physiological conditions, leading to the onset of protein adsorption when exposed to plasma or blood. Paralleling the protein adsorption behavior and onset of coating degradation observed in vitro, blood clearance of parenterally administered PEG coated particles in mice began after approximately 2h of circulation time. Taken together, the data presented in this work indicates that the stability of the PEG coating and the many factors affecting it represent a fundamental limitation to the use of these particles.

Thermal degradation kinetics of phycocyanin encapsulation as an antioxidant agent

NASA Astrophysics Data System (ADS)

Nilamsari, A. M.; Yunanda, A.; Hadiyanto, H.

2018-01-01

Phycocyanin is a blue-light pigment that found in Cyanobacteria and two Eukaryotics algae such as Rhodophyta and Crytophyta. Phycocyanin is soluble in water and has a strong fluorescent properties as an antioxidant and normally used in food industry, cosmetic, biotechnology, and drug. However, Phycocyanin is easily damaged by a heating process. The aim of this study is to obtain the optimal condition of phycocyanin encapsulation with different coating materials, Chitosan and Carrageenan, by the calculation of heat resistance of antioxidant activity (D), range of temperature that increase the rate of degradation (Z), rate constant of degradation (k), and activation energy (Ea). The ratio of phycocyanin and the coating material are 2% (w/v) and 2 % (w/v).

Characterization of chemical agent transport in paints.

PubMed

Willis, Matthew P; Gordon, Wesley; Lalain, Teri; Mantooth, Brent

2013-09-15

A combination of vacuum-based vapor emission measurements with a mass transport model was employed to determine the interaction of chemical warfare agents with various materials, including transport parameters of agents in paints. Accurate determination of mass transport parameters enables the simulation of the chemical agent distribution in a material for decontaminant performance modeling. The evaluation was performed with the chemical warfare agents bis(2-chloroethyl) sulfide (distilled mustard, known as the chemical warfare blister agent HD) and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), an organophosphate nerve agent, deposited on to two different types of polyurethane paint coatings. The results demonstrated alignment between the experimentally measured vapor emission flux and the predicted vapor flux. Mass transport modeling demonstrated rapid transport of VX into the coatings; VX penetrated through the aliphatic polyurethane-based coating (100 μm) within approximately 107 min. By comparison, while HD was more soluble in the coatings, the penetration depth in the coatings was approximately 2× lower than VX. Applications of mass transport parameters include the ability to predict agent uptake, and subsequent long-term vapor emission or contact transfer where the agent could present exposure risks. Additionally, these parameters and model enable the ability to perform decontamination modeling to predict how decontaminants remove agent from these materials. Published by Elsevier B.V.

Evaluation of coated metallic bipolar plates for polymer electrolyte membrane fuel cells

NASA Astrophysics Data System (ADS)

Yoon, Wonseok; Huang, Xinyu; Fazzino, Paul; Reifsnider, Kenneth L.; Akkaoui, Michael A.

Metallic bipolar plates for polymer electrolyte membrane (PEM) fuel cells typically require coatings for corrosion protection. Other requirements for the corrosion protective coatings include low electrical contact resistance, good mechanical robustness, low material and fabrication cost. The authors have evaluated a number of protective coatings deposited on stainless steel substrates by electroplating and physical vapor deposition (PVD) methods. The coatings are screened with an electrochemical polarization test for corrosion resistance; then the contact resistance test was performed on selected coatings. The coating investigated include Gold with various thicknesses (2 nm, 10 nm, and 1 μm), Titanium, Zirconium, Zirconium Nitride (ZrN), Zirconium Niobium (ZrNb), and Zirconium Nitride with a Gold top layer (ZrNAu). The substrates include three types of stainless steel: 304, 310, and 316. The results show that Zr-coated samples satisfy the DOE target for corrosion resistance at both anode and cathode sides in typical PEM fuel cell environments in the short-term, but they do not meet the DOE contact resistance goal. Very thin gold coating (2 nm) can significantly decrease the electrical contact resistance, however a relatively thick gold coating (>10 nm) with our deposition method is necessary for adequate corrosion resistance, particularly for the cathode side of the bipolar plate.

Genipin crosslinker releasing sutures for improving the mechanical/repair strength of damaged connective tissue.

PubMed

Sundararaj, Sharath; Slusarewicz, Paul; Brown, Matt; Hedman, Thomas

2017-11-01

The most common mode of surgical repair of ruptured tendons and ligaments involves the use of sutures for reattachment. However, there is a high incidence of rerupture and repair failure due to pulling out of the suture material from the damaged connective tissue. The main goal of this research was to achieve a localized delivery of crosslinking agent genipin (GP) from rapid-release biodegradable coatings on sutures, for strengthening the repair of ruptured connective tissue. Our hypothesis is that GP released from the suture coating will lead to exogenous crosslinking of native connective tissue resulting in beneficial effects on clinically relevant mechanical parameters such as tear resistance, tissue strength, and energy required to rupture the tissue (toughness). Sutures were successfully coated with a biodegradable polymer layer loaded with the crosslinking agent genipin, without compromising the mechanical properties of the suture. The rapid-release of genipin was achieved under both in vitro and ex vivo conditions. Exogenous crosslinking using these genipin releasing sutures was demonstrated using equine tendons. The tendons treated with genipin releasing sutures showed significant improvement in failure load, energy required for pull-out failure, and stiffness. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2199-2205, 2017. © 2016 Wiley Periodicals, Inc.

Research into properties of wear resistant ceramic metal plasma coatings

NASA Astrophysics Data System (ADS)

Ivancivsky, V. V.; Skeeba, V. Yu; Zverev, E. A.; Vakhrushev, N. V.; Parts, K. A.

2018-03-01

The study considers one of the promising ways to improve the quality of wear resistant plasma ceramic coatings by implementing various powder mixtures. The authors present the study results of the nickel-ceramic and cobalt-ceramic coating properties and describe the specific character of the investigated coatings composition. The paper presents the results of the coating microhardness, chemical and adhesive strength studies. The authors conducted wear resistance tests of composite coatings in comparison with the plasma coatings of initial powder components.

Development of high temperature resistant graphite fiber coupling agents

NASA Technical Reports Server (NTRS)

Griffin, R. N.

1975-01-01

Surface treatments were investigated as potential coupling agents to improve the elevated temperature shear strength retention of polyimide/graphite and polyphenylquinoxaline/graphite composites. The potential coupling agents were evaluated by fiber strand tensile tests, fiber and composite weight losses at 533 and 588K, and by interlaminar shear strength retention at 533 and 588K. The two surface treatments selected for more extensive evaluation were a coating of Ventromer T-1, a complex organometallic reaction product of titanium tetrachloride and trimethyl borate, and a polyphenylquinoxaline (PPQ) sizing which was pyrolyzed in nitrogen to form a carbonaceous layer on the fiber. Pyrolyzed polyphenylquinoxaline is a satisfactory coupling agent for polyimide/Thornel 300 graphite fiber composites. During 1000 hours aging at 588K such composites lose a little over half their transverse tensile strength, and suffer a slight loss in flexural modulus. No degradation of flexural strength or interlaminar shear strength occured during 1000 hours aging at 588K. None of the coupling agents examined had a markedly beneficial effect with polyphenylquinoxaline composites.

Improved fire-resistant coatings

NASA Technical Reports Server (NTRS)

Hutt, J. B.; Stuart, J. W.

1971-01-01

Water-base coatings containing potassium silicate show improvement in areas of quick air-drying, crack, craze, and abrasion resistance, adherence, and leach resistance. Coatings are useful as thermal-barrier layers in furnaces, and as general purpose fire resistant surfaces where vapor impermeability is not a requirement.

pH-resistant titania hybrid organic-inorganic sol-gel coating for solid-phase microextraction of polar compounds.

PubMed

Li, Xiujuan; Gao, Jie; Zeng, Zhaorui

2007-05-02

A novel titania-hydroxy-terminated silicone oil (titania-OH-TSO) sol-gel coating was developed for solid-phase microextraction of polar compounds. In general, titania-based sol-gel reaction is very fast and need to be decelerated by the use of suitable chelating agents. But in the present work, a judiciously designed sol solution ingredients was used to create the titania-OH-TSO coating without the addition of any chelating agent, which simplified the sol-gel procedure. Thanks to the variety of titania's adsorption sites and their acid-base characteristics, aromatic amines, phenols and polycyclic aromatic hydrocarbons were efficiently extracted and preconcentrated from aqueous samples followed by thermal desorption and GC analysis. The newly developed sol-gel hybrid titania coating demonstrated excellent pH stability, and retained its extraction characteristics intact even after continuous rinsing with a 3 M HCl or NaOH solution for 12 h. Furthermore, it could withstand temperatures as high as 320 degrees C. Practical application was demonstrated through the analysis of six aromatic amines in dye process wastewater. A linearity of four orders of magnitude was obtained with correlation coefficient better than 0.9982. The detection limits ranged from 0.22 to 0.84 microg L(-1) and the repeatability of the measurements was <7.0%. The recoveries of these compounds studied in the wastewater were in the ranges 83.6-101.4%, indicating the method accuracy.

Hydrophobic Coatings on Cotton Obtained by in Situ Plasma Polymerization of a Fluorinated Monomer in Ethanol Solutions.

PubMed

Molina, Ricardo; Teixidó, Josep Maria; Kan, Chi-Wai; Jovančić, Petar

2017-02-15

Plasma polymerization using hydrophobic monomers in the gas phase is a well-known technology to generate hydrophobic coatings. However, synthesis of functional hydrophobic coatings using plasma technology in liquids has not yet been accomplished. This work is consequently focused on polymerization of a liquid fluorinated monomer on cotton fabric initiated by atmospheric plasma in a dielectric barrier discharge configuration. Functional hydrophobic coatings on cotton were successfully achieved using in situ atmospheric plasma-initiated polymerization of fluorinated monomer dissolved in ethanol. Gravimetric measurements reveal that the amount of polymer deposited on cotton substrates can be modulated with the concentration of monomer in ethanol solution, and cross-linking reactions occur during plasma polymerization of a fluorinated monomer even without the presence of a cross-linking agent. FTIR and XPS analysis were used to study the chemical composition of hydrophobic coatings and to get insights into the physicochemical processes involved in plasma treatment. SEM analysis reveals that at high monomer concentration, coatings possess a three-dimensional pattern with a characteristic interconnected porous network structure. EDX analysis reveals that plasma polymerization of fluorinated monomers takes place preferentially at the surface of cotton fabric and negligible polymerization takes place inside the cotton fabric. Wetting time measurements confirm the hydrophobicity of cotton coatings obtained although equilibrium moisture content was slightly decreased. Additionally, the abrasion behavior and resistance to washing of plasma-coated cotton has been evaluated.

Edible coating as carrier of antimicrobial agents to extend the shelf life of fresh-cut apples

USDA-ARS?s Scientific Manuscript database

Edible coatings with antimicrobial agents can extend shelf-life of fresh-cut fruits. The effect of lemongrass, oregano oil and vanillin incorporated in apple puree-alginate edible coatings, on shelf-life of fresh-cut 'Fuji' apples, was investigated. Coated apples were packed in air filled polypropyl...

Corrosion-resistant, electrically-conductive plate for use in a fuel cell stack

DOEpatents

Carter, J David [Bolingbrook, IL; Mawdsley, Jennifer R [Woodridge, IL; Niyogi, Suhas [Woodridge, IL; Wang, Xiaoping [Naperville, IL; Cruse, Terry [Lisle, IL; Santos, Lilia [Lombard, IL

2010-04-20

A corrosion resistant, electrically-conductive, durable plate at least partially coated with an anchor coating and a corrosion resistant coating. The corrosion resistant coating made of at least a polymer and a plurality of corrosion resistant particles each having a surface area between about 1-20 m.sup.2/g and a diameter less than about 10 microns. Preferably, the plate is used as a bipolar plate in a proton exchange membrane (PEMFC) fuel cell stack.

"Effect of nano-filled surface coating agent on fluoride release from conventional glass ionomer cement: an in vitro trial".

PubMed

Tiwari, S; Nandlal, B

2013-01-01

To overcome the drawbacks of glass ionomer cement of sensitivity to initial desiccation and moisture contamination the use of surface coating agent is recommended. The search in this area led to invent of use of nanofillers in surface coating agent, but its effect on fluoride release is not clear. The aim of this study is to evaluate and compare the fluoride release from conventional glass ionomer cement with and without surface coating agent. This in vitro study comprised of total 80 samples (40 samples of each with and without surface coating). Specimens were prepared, G coat plus was applied and light cured. Fluoride release of the sample was measured every 24 h for 7 days and weekly from 7th to 21 st day using Sension4 pH/ISE/MV Meter. Descriptive Statistics, Repeated Measure ANOVA, Paired Sample t-test, Independent Sample t-test, Scheffe post hoc test. Mean values clearly reveal a significant decrease in the fluoride release from day 1 to day 21 for both groups. Non-coated group released significantly more fluoride than surface coated group (P<0.001). It can be concluded that nanofilled surface coating agent will reduce the amount of fluoride released into oral environment as compared to non-coated group and at the same time releasing fluoride into surrounding cavity walls to create zones of inhibition into the cavity floor to help internal remineralization.

Wear and Corrosion Resistance of Thick Ti-6Al-4V Coating Deposited on Ti-6Al-4V Substrate via High-Pressure Cold Spray

NASA Astrophysics Data System (ADS)

Khun, N. W.; Tan, A. W. Y.; Sun, W.; Liu, E.

2017-08-01

Ti-6Al-4V (Ti64) coating with a thickness of about 9 mm was deposited on commercial Ti64 substrate via a high-pressure cold spray process. The microstructure, hardness, and wear and corrosion resistance of the Ti64 coating were systematically investigated. The hardness of the Ti64 coating was higher than that of the Ti64 substrate due to the cold-worked microstructure of the coating. The tribological results showed that there was no significant difference in the surface wear rates of the Ti64 coating measured on its different layers while the surface wear resistance of the Ti64 coating was lower than its cross-sectional wear resistance. The corrosion results showed that the Ti64 coating did not effectively prevent its underlying Ti64 substrate from corrosion due to the occurrence of pores in the coating microstructure. It could be concluded that the hardness and wear resistance of the Ti64 coating were comparable to those of the commercial Ti64 substrate.

A new diffusion-inhibited oxidation-resistant coating for superalloys

NASA Technical Reports Server (NTRS)

Gedwill, M. A.; Glasgow, T. K.; Levine, S. R.

1981-01-01

A concept for enhanced protection of superalloys consists of adding an oxidation- and diffusion-resistant cermet layer between the superalloy and the outer oxidation-resistant metallic alloy coating. Such a duplex coating was compared with a physical-vapor-deposited (PVD) NiCrAlY coating in cyclic oxidation at 1150 C. The substrate alloy was MA 754 - an oxide-dispersion-strengthened superalloy that is difficult to coat. The duplex coating, applied by plasma spraying, outperformed the PVD coating on the basis of weight change and both macroscopic and metallographic observations.

Inorganic-organic hybrid coatings on stainless steel by layer-by-layer deposition and surface-initiated atom-transfer-radical polymerization for combating biocorrosion.

PubMed

Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

2009-03-01

To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.

Galvanic Liquid Applied Coating System For Protection of Embedded Steel Surfaces from Corrosion

NASA Technical Reports Server (NTRS)

Curran, Joseph; Curran, Jerome; Voska, N. (Technical Monitor)

2002-01-01

Corrosion of reinforcing steel in concrete is an insidious problem facing Kennedy Space Center (KSC), other Government Agencies, and the general public. These problems include KSC launch support structures, highway bridge infrastructure, and building structures such as condominium balconies. Due to these problems, the development of a Galvanic Liquid Applied Coating System would be a breakthrough technology having great commercial value for the following industries: Transportation, Infrastructure, Marine Infrastructure, Civil Engineering, and the Construction Industry. This sacrificial coating system consists of a paint matrix that may include metallic components, conducting agents, and moisture attractors. Similar systems have been used in the past with varying degrees of success. These systems have no proven history of effectiveness over the long term. In addition, these types of systems have had limited success overcoming the initial resistance between the concrete/coating interface. The coating developed at KSC incorporates methods proven to overcome the barriers that previous systems could not achieve. Successful development and continued optimization of this breakthrough system would produce great interest in NASA/KSC for corrosion engineering technology and problem solutions. Commercial patents on this technology would enhance KSC's ability to attract industry partners for similar corrosion control applications.

Performance of Selected Fabrics on the Decontaminable Litter and Litter Mattress to Correct a Problem of Unexpected Sliding during Patient Loading on a C-9 (Nightingale) Aircraft

DTIC Science & Technology

1992-01-30

Agent Resistant Coating, retractable nylon handles, ethylene propylenediene monomer ( EPDM ) rubber securing straps, and a woven monofilament polypropylene...without Z-folds: overlapping layers of fabric sewn as reinforcement in the cover opposite the spreader bars. These covers were made from fabrics that...problem is not isolated to the decon litter and mattress. Comparable slippage should be expected when the vinyl mattress is used with the new nylon

Improving the packing density of calcium phosphate coating on a magnesium alloy for enhanced degradation resistance.

PubMed

Kannan, M Bobby

2013-05-01

In this study, an attempt was made to improve the packing density of calcium phosphate (CaP) coating on a magnesium alloy by tailoring the coating solution for enhanced degradation resistance of the alloy for implant applications. An organic solvent, ethanol, was added to the coating solution to decrease the conductivity of the coating solution so that hydrogen bubble formation/bursting reduces during the CaP coating process. Experimental results confirmed that ethanol addition to the coating solution reduces the conductivity of the solution and also decreases the hydrogen evolution/bubble bursting. In vitro electrochemical experiments, that is, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization showed that CaP coating produced in 30% (v/v) ethanol containing coating solution (3E) exhibits significantly higher degradation resistance (i.e., ~50% higher polarization resistance and ~60% lower corrosion current) than the aqueous solution coating. Scanning electron microscope (SEM) analysis of the coatings revealed that the packing of 3E coating was denser than that of aqueous coating, which can be attributed to the lower hydrogen evolution in the former than in the latter. Further increase in the ethanol content in the coating solution was not beneficial; in fact, the coating produced in 70% (v/v) ethanol containing solution (7E) showed degradation resistance much inferior to that of the aqueous coating, which is due to low thickness of 7E coating. Copyright © 2012 Wiley Periodicals, Inc.

Interaction of Bacillus subtilis spores with sodium hypochlorite, sodium dichloroisocyanurate and chloramine-T.

PubMed

Bloomfield, S F; Arthur, M

1992-02-01

Solutions of chlorine-releasing agents (CRAs) show varying activity against Bacillus subtilis spores; sodium hypochlorite (NaOCl) shows higher activity than sodium dichloroisocyanurate (NaDCC) which is more active than chloramine-T. Investigations with coat- and cortex-extracted spores indicate that resistance to CRAs depends not only on the spore coat but also the cortex. Whereas extraction of alkali-soluble coat protein increased sensitivity to NaOCl and NaDCC, degradation of coat and cortex material was required to achieve significant activity with chloramine-T. NaOCl (in the presence and absence of NaOH) and NaDCC (in the presence of NaOH only) produced degradation of spore coat and cortex material which may be related to their rapid sporicidal action at low concentrations under these conditions. By contrast, chloramine-T produced no degradation of cortex peptidoglycan and was only effective against normal and alkali-treated spores at high concentrations, requiring extraction of peptidoglycan with urea/dithiothreitol/sodium lauryl sulphate (UDS) or UDS/lysozyme to achieve significant activity at low concentrations. Results suggest that the sporicidal action of CRAs is associated with spore coat and cortex degradation causing rehydration of the protoplast allowing diffusion to the site of action on the underlying protoplast.

Enzyme-coated mesoporous silica nanoparticles as efficient antibacterial agents in vivo.

PubMed

Li, Li-Li; Wang, Hao

2013-10-01

Despite the fact that pathogenic infections are widely treated by antibiotics in the clinic nowadays, the increasing risk of multidrug-resistance associated with abuse of antibiotics is becoming a major concern in global public health. The increased death toll caused by pathogenic bacterial infection calls for effective antibiotic alternatives. Lysozyme-coated mesoporous silica nanoparticles (MSNs⊂Lys) are reported as antibacterial agents that exhibit efficient antibacterial activity both in vitro and in vivo with low cytotoxicity and negligible hemolytic side effect. The Lys corona provides multivalent interaction between MSNs⊂Lys and bacterial walls and consequently raises the local concentration of Lys on the surface of cell walls, which promotes hydrolysis of peptidoglycans and increases membrane-perturbation abilities. The minimal inhibition concentration (MIC) of MSNs⊂Lys is fivefold lower than that of free Lys in vitro. The antibacterial efficacy of MSNs⊂Lys is evaluated in vivo by using an intestine-infected mouse model. Experimental results indicate that the number of bacteria surviving in the colon is three orders of magnitude lower than in the untreated group. These natural antibacterial enzyme-modified nanoparticles open up a new avenue for design and synthesis of next-generation antibacterial agents as alternatives to antibiotics. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anti-thrombogenicity and permeability of polyethersulfone hollow fiber membrane with sulfonated alginate toward blood purification.

PubMed

Salimi, Esmaeil; Ghaee, Azadeh; Ismail, Ahmad Fauzi; Karimi, Majid

2018-04-30

The main aim of this study was to evaluate the suitability of sulfonated alginate as a modifying agent to enhance the hemocompatibility of self-fabricated polyethersulfone (PES) hollow fiber membrane for blood detoxification. Sodium alginate was sulfonated with a degree of 0.6 and immobilized on the membrane via surface amination and using glutaraldehyde as cross-linking agent. Coating layer not only improved the membrane surface hydrophilicity, but also induced -39.2 mV negative charges on the surface. Water permeability of the modified membrane was enhanced from 67 to 95 L/m 2 ·h·bar and flux recovery ratio increased more than 2-fold. Furthermore, the modified membrane presented higher platelet adhesion resistance (reduced by more than 90%) and prolonged coagulation time (35 s for APTT and 14 s for PT) in comparison with the pristine PES hollow fiber membrane, which verified the improved anti-thrombogenicity of the modified membrane. On the other hand, obtained membrane after 3 h coating could remove up-to 60% of the uremic toxins. According to the obtained data, sulfonated alginate can be a promising modifying agent for the future blood-contacting membrane and specially blood purification issues. Copyright © 2018 Elsevier B.V. All rights reserved.

Priming cells for their final destination: microenvironment controlled cell culture by a modular ECM-mimicking feeder film.

PubMed

Barthes, Julien; Vrana, Nihal E; Özçelik, Hayriye; Gahoual, Rabah; François, Yannis N; Bacharouche, Jalal; Francius, Grégory; Hemmerlé, Joseph; Metz-Boutigue, Marie-Hélène; Schaaf, Pierre; Lavalle, Philippe

2015-09-01

Mammalian cell culture is the starting point in many research studies focusing on biomedical applications. However, researchers have little control over the standardized cell microenvironment parameters. Here a modular ECM-mimicking surface coating for cell culture environment is designed. This substrate is a new and versatile thin film obtained by spin-coating of concentrated gelatin crosslinked by transglutaminase. It can be modified with respect to the biochemical and biophysical needs of the final cell destination, i.e. it delivers loaded multi-growth factors and serum components and allows for cell culture in a serum-free culture medium. Also, a well-known cell behavior modulator, the substrate stiffness, is controlled exogenously by addition of nanoparticles. In addition to growth factors, antimicrobial agents such as natural peptides are added to the substrate for limiting the repeated addition of antimicrobial agents to the culture medium and to prevent the increase of resistant bacterial strains in the culture environment. Finally, this substrate contains simultaneously ECM components, growth factors, stiffening elements and antimicrobial agents. It provides a favorable microenvironment and sterile conditions. It is a free-of-maintenance system, as cells will grow without addition of serum or antimicrobial cocktails. This low cost and easy-to-use substrate could emerge as a new standard for cell culture.

Coatings for graphite fibers

NASA Technical Reports Server (NTRS)

Galasso, F. S.; Scola, D. A.; Veltri, R. D.

1980-01-01

Graphite fibers released from composites during burning or an explosion caused shorting of electrical and electronic equipment. Silicon carbide, silica, silicon nitride and boron nitride were coated on graphite fibers to increase their electrical resistances. Resistances as high as three orders of magnitude higher than uncoated fiber were attained without any significant degradation of the substrate fiber. An organo-silicone approach to produce coated fibers with high electrical resistance was also used. Celion 6000 graphite fibers were coated with an organo-silicone compound, followed by hydrolysis and pyrolysis of the coating to a silica-like material. The shear and flexural strengths of composites made from high electrically resistant fibers were considerably lower than the shear and flexural strengths of composites made from the lower electrically resistant fibers. The lower shear strengths of the composites indicated that the coatings on these fibers were weaker than the coating on the fibers which were pyrolyzed at higher temperature.

Resistance to Corrosion of Zirconia Coatings Deposited by Spray Pyrolysis in Nitrided Steel

NASA Astrophysics Data System (ADS)

Cubillos, G. I.; Olaya, J. J.; Bethencourt, M.; Cifredo, G.; Blanco, G.

2013-10-01

Coatings of zirconium oxide were deposited onto three types of stainless steel, AISI 316L, 2205, and tool steel AISI D2, using the ultrasonic spray pyrolysis method. The effect of the flux ratio on the process and its influence on the structure and morphology of the coatings were investigated. The coatings obtained, 600 nm thick, were characterized using x-ray diffraction, scanning electron microscopy, confocal microscopy, and atomic force microscopy. The resistance to corrosion of the coatings deposited over steel (not nitrided) and stainless steel nitrided (for 2 h at 823 K) in an ammonia atmosphere was evaluated. The zirconia coating enhances the stainless steel's resistance to corrosion, with the greatest increase in corrosion resistance being observed for tool steel. When the deposition is performed on previously nitrided stainless steel, the morphology of the surface improves and the coating is more homogeneous, which leads to an improved corrosion resistance.

Investigation of X-ray permeability of surgical gloves coated with different contrast agents

PubMed Central

Kayan, Mustafa; Yaşar, Selçuk; Saygın, Mustafa; Yılmaz, Ömer; Aktaş, Aykut Recep; Kayan, Fatmanur; Türker, Yasin; Çetinkaya, Gürsel

2016-01-01

Objective: We aimed to investigate the effectiveness and radiation protection capability of latex gloves coated with various contrast agents as an alternative to lead gloves. Methods: The following six groups were created to evaluate the permeability of X-ray in this experimental study: lead gloves, two different non-ionic contrast media (iopromide 370/100 mg I/mL and iomeprol 400/100 mg I/mL), 10% povidone–iodine (PV–I), 240/240 g/mL barium sulphate and a mixture of equal amounts of all contrast agents. A radiation dose detector was placed in coated latex gloves for each one. The absorption values of radiation from latex gloves coated with various contrast agents were measured and compared with the absorption of radiation from lead gloves. This study was designed as an ‘experimental study’. Results: The mean absorption value of X-ray from lead gloves was 3.0±0.08 µG/s. The mean absorption values of X-ray from latex gloves coated with various contrast agents were 3.7±0.09 µG/s (iopromide 370/100 mg I/mL), 3.6±0.09 µG/s (iomeprol 400/100 mg I/mL), 3.7±0.04 µG/s (PV–I), 3.1±0.07 µG/s (barium sulphate) and 3.8±0.05 µG/s (mixture of all contrast agents). Latex gloves coated with barium sulphate provided the best radiation absorption compared with latex gloves coated with other radiodense contrast agents. Conclusion: Latex gloves coated with barium sulphate may provide protection equivalent to lead gloves. PMID:26680548

Anticorrosion performance of chromized coating prepared by pack cementation in simulated solution with H2S and CO2

NASA Astrophysics Data System (ADS)

Wang, Qin-Ying; Behnamian, Yashar; Luo, Hong; Wang, Xian-Zong; Leitch, Michael; Zeng, Hongbo; Luo, Jing-Li

2017-10-01

A hash service environment containing H2S and CO2 in oil industry usually causes corrosion of carbon steel. In this study, the chromized coatings with different deposited time were prepared on the surface of carbon steel by the method of pack cementation to enhance its corrosion resistance. Then the microstructure, hardness, corrosion resistance as well as the semiconductor behavior of coatings in the simulated solution with saturated H2S and CO2 were investigated. The results show that the content of Cr in coating was increased by prolonging deposited time, and both chromium carbides and chromium nitrides were formed. Furthermore, coatings display higher polarization resistance, Rp, than that of the substrate, indicating a higher resistance to charge transfer on coating surface. The corrosion rates of coatings with different deposited time were significantly lower than that of substrate. Chemical analysis showed the formation of heavy sulfides on the surface of substrates after corrosion, while the least corrosion products were detected on the surface of coating with deposited time of 12 h. Mott-Schottky results indicated that coating of 12 h displayed less defects than the other two coatings with deposited time of 4 h and 8 h, which will be beneficial to improve corrosion resistance. The investigation showed that chromized coatings exhibited high corrosion resistance and owned a potential application in oil industry for corrosion prevention.

Investigations on the corrosion resistance of metallic bipolar plates (BPP) in proton exchange membrane fuel cells (PEMFC) - understanding the effects of material, coating and manufacturing

NASA Astrophysics Data System (ADS)

Dur, Ender

Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems are promising technology for contributing to meet the deficiency of world`s clean and sustainable energy requirements in the near future. Metallic bipolar plate (BPP) as one of the most significant components of PEMFC device accounts for the largest part of the fuel cell`s stack. Corrosion for metallic bipolar plates is a critical issue, which influences the performance and durability of PEMFC. Corrosion causes adverse impacts on the PEMFC`s performance jeopardizing commercialization. This research is aimed at determining the corrosion resistance of metallic BPPs, particularly stainless steels, used in PEMFC from different aspects. Material selection, coating selection, manufacturing process development and cost considerations need to be addressed in terms of the corrosion behavior to justify the use of stainless steels as a BPP material in PEMFC and to make them commercially feasible in industrial applications. In this study, Ti, Ni, SS304, SS316L, and SS 430 blanks, and BPPs comprised of SS304 and SS316L were examined in terms of the corrosion behavior. SS316L plates were coated to investigate the effect of coatings on the corrosion resistance performance. Stamping and hydroforming as manufacturing processes, and three different coatings (TiN, CrN, ZrN) applied via the Physical Vapor Deposition (PVD) method in three different thicknesses were selected to observe the effects of manufacturing processes, coating types and coating thicknesses on the corrosion resistance of BPP, respectively. Uncoated-coated blank and formed BPP were subjected to two different corrosion tests: potentiostatic and potentiodynamic. Some of the substantial results: 1- Manufacturing processes have an adverse impact on the corrosion resistance. 2- Hydroformed plates have slightly higher corrosion resistance than stamped samples. 3- BPPs with higher channel size showed better corrosion resistance. 4- Since none of the uncoated samples meet the 2015 target of the U.S. Department of Energy, surface coating is required. 5- ZrN and CrN coated BPPs exhibited higher corrosion resistance meeting DOE target while TiN coated samples had the lowest corrosion resistance. Higher coating thicknesses improved the corrosion resistance of the BPPs. 6- Process sequence between coating and manufacturing is not significant for hydroforming case (ZrN and CrN) and stamping case (CrN) in terms of the corrosion resistance. In other words, coating the BPP`s substrate material before manufacturing process does not always decrease the corrosion resistance of the BPPs.

40 CFR 59.101 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... promote a faster cure of an enamel finish. Impact-resistant coating means a coating designed to resist... in its original solvent. Low-gloss coating means a coating which exhibits a gloss reading less than...

40 CFR 59.101 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... promote a faster cure of an enamel finish. Impact-resistant coating means a coating designed to resist... in its original solvent. Low-gloss coating means a coating which exhibits a gloss reading less than...

Medical implants and methods of making medical implants

DOEpatents

Shaw, Wendy J; Yonker, Clement R; Fulton, John L; Tarasevich, Barbara J; McClain, James B; Taylor, Doug

2014-09-16

A medical implant device having a substrate with an oxidized surface and a silane derivative coating covalently bonded to the oxidized surface. A bioactive agent is covalently bonded to the silane derivative coating. An implantable stent device including a stent core having an oxidized surface with a layer of silane derivative covalently bonded thereto. A spacer layer comprising polyethylene glycol (PEG) is covalently bonded to the layer of silane derivative and a protein is covalently bonded to the PEG. A method of making a medical implant device including providing a substrate having a surface, oxidizing the surface and reacting with derivitized silane to form a silane coating covalently bonded to the surface. A bioactive agent is then covalently bonded to the silane coating. In particular instances, an additional coating of bio-absorbable polymer and/or pharmaceutical agent is deposited over the bioactive agent.

Improvement of wear resistance of plasma-sprayed molybdenum blend coatings

NASA Astrophysics Data System (ADS)

Ahn, Jeehoon; Hwang, Byoungchul; Lee, Sunghak

2005-06-01

The wear resistance of plasma sprayed molybdenum blend coatings applicable to synchronizer rings or piston rings was investigated in this study. Four spray powders, one of which was pure molybdenum and the others blended powders of bronze and aluminum-silicon alloy powders mixed with molybdenum powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the coatings showed that the phases formed during spraying were relatively homogeneously distributed in the molybdenum matrix. The wear test results revealed that the wear rate of all the coatings increased with increasing wear load and that the blended coatings exhibited better wear resistance than the pure molybdenum coating, although the hardness was lower. In the pure molybdenum coatings, splats were readily fractured, or cracks were initiated between splats under high wear loads, thereby leading to the decrease in wear resistance. On the other hand, the molybdenum coating blended with bronze and aluminum-silicon alloy powders exhibited excellent wear resistance because hard phases such as CuAl2 and Cu9Al4 formed inside the coating.

Low surface energy polymeric release coating for improved contact print lithography

NASA Astrophysics Data System (ADS)

Mancini, David P.; Resnick, Douglas J.; Gehoski, Kathleen A.; Popovich, Laura L.; Chang, Daniel

2002-03-01

Contact printing has been used for decades in many various lithography applications in the microelectronic industry. While vacuum contact printing processes offer sub-micron resolution and high throughput, they often suffer from some important drawbacks. One of the most common problems is degradation in both resolution and defect density which occurs when the same mask si used for multiple exposures without frequent mask cleans. This is largely due to the relatively high surface energy of both quartz and chrome and the tendency of most photoresists to adhere to these surfaces. As a result, when a mask and wafer are pressed into intimate contact, resist will tend to stick to the mask creating a defect on the wafer, effectively propagating defects to subsequent wafers. In this study, DuPont Teflon AF 1601S is used as a photomask coating and evaluated for its ability to act as a release agent and reduce defects while maintaining resolution for multiple exposures. Teflon AF is an amorphous, transparent, low surface energy, polymeric material that can be spin coated into a thin conformal film. Tests have shown that when using an uncoated mask in vacuum contact, resolution of 0.75 micrometers dense lines is severely degraded after less than 10 consecutive exposures. However, when the mask is coated, 0.75 micrometers dense lines were successfully resolved using vacuum contact for over 200 exposures without cleaning. In addition, it has been demonstrated that Teflon AF coatings impart to a mask a self-cleaning capability, since particles tend to stick to the photoresist rather than the mask. A coated mask, which was purposefully contaminated with particulates, resolved 0.75 micrometers dense lines on all but the first wafer of a series of 25 consecutive exposures. The patented mask releases layer process has successfully been demonstrated with a positive novolak resist. Additional data which describes the system chemistry, dilution and coating process, and film morphology are also presented.

Combination of Functional Nanoengineering and Nanosecond Laser Texturing for Design of Superhydrophobic Aluminum Alloy with Exceptional Mechanical and Chemical Properties.

PubMed

Boinovich, Ludmila B; Modin, Evgeny B; Sayfutdinova, Adeliya R; Emelyanenko, Kirill A; Vasiliev, Alexander L; Emelyanenko, Alexandre M

2017-10-24

Industrial application of metallic materials is hindered by several shortcomings, such as proneness to corrosion, erosion under abrasive loads, damage due to poor cold resistance, or weak resistance to thermal shock stresses, etc. In this study, using the aluminum-magnesium alloy as an example of widely spread metallic materials, we show that a combination of functional nanoengineering and nanosecond laser texturing with the appropriate treatment regimes can be successfully used to transform a metal into a superhydrophobic material with exceptional mechanical and chemical properties. It is demonstrated that laser chemical processing of the surface may be simultaneously used to impart multimodal roughness and to modify the composition and physicochemical properties of a thick surface layer of the substrate itself. Such integration of topographical and physicochemical modification leads to specific surface nanostructures such as nanocavities filled with hydrophobic agent and hard oxynitride nanoinclusions. The combination of superhydrophobic state, nano- and micro features of the hierarchical surface, and the appropriate composition of the surface textured layer allowed us to provide the surface with the outstanding level of resistance of superhydrophobic coatings to external chemical and mechanical impacts. In particular, experimental data presented in this study indicate high resistance of the fabricated coatings to pitting corrosion, superheated water vapor, sand abrasive wear, and rapid temperature cycling from liquid nitrogen to room temperatures, without notable degradation of superhydrophobic performance.

Effects of annealing heat treatment on the corrosion resistance of Zn/Mg/Zn multilayer coatings

NASA Astrophysics Data System (ADS)

Bae, KiTae; La, JoungHyun; Lee, InGyu; Lee, SangYul; Nam, KyungHoon

2017-05-01

Zn coatings alloyed with magnesium offer superior corrosion resistance compared to pure Zn or other Zn-based alloy coatings. In this study, Zn/Mg/Zn multilayer coatings with various Mg layer thicknesses were synthesized using an unbalanced magnetron sputtering process and were annealed to form Zn-Mg intermetallic phases. The effects of the annealing heat treatment on the corrosion resistance of the Zn/Mg/Zn multilayer coatings were evaluated using electrochemical measurements. The extensive diffusion of magnesium species into the upper and lower zinc layer from the magnesium layer in the middle of the coating was observed after the heat treatment. This phenomenon caused (a) the porous microstructure to transition into a dense structure and (b) the formation of a MgZn2 intermetallic phase. The results of the electrochemical measurements demonstrated that the heat treated Zn/Mg/Zn multilayer coatings possessed higher levels of corrosion resistance than the non-heat treated coatings. A Zn/Mg/Zn multilayer coating with MgZn2 and (Zn) phases showed the best corrosion resistance among the heat treated coatings, which could be attributed to the reduced galvanic corrosion effects due to a small potential gradient between the MgZn2 and zinc.

Coatings for Graphite Fibers

NASA Technical Reports Server (NTRS)

Galasso, F. S.; Scola, D. A.; Veltri, R. D.

1980-01-01

Several approaches for applying high resistance coatings continuously to graphite yarn were investigated. Two of the most promising approaches involved (1) chemically vapor depositing (CVD) SiC coatings on the surface of the fiber followed by oxidation, and (2) drawing the graphite yarn through an organo-silicone solution followed by heat treatments. In both methods, coated fibers were obtained which exhibited increased electrical resistances over untreated fibers and which were not degraded. This work was conducted in a previous program. In this program, the continuous CVD SiC coating process used on HTS fiber was extended to the coating of HMS, Celion 6000, Celion 12000 and T-300 graphite fiber. Electrical resistances three order of magnitude greater than the uncoated fiber were measured with no significant degradation of the fiber strength. Graphite fibers coated with CVD Si3N4 and BN had resistances greater than 10(exp 6) ohm/cm. Lower pyrolysis temperatures were used in preparing the silica-like coatings also resulting in resistances as high as three orders of magnitude higher than the uncoated fiber. The epoxy matrix composites prepared using these coated fibers had low shear strengths indicating that the coatings were weak.

Selection criteria for wear resistant powder coatings under extreme erosive wear conditions

NASA Astrophysics Data System (ADS)

Kulu, P.; Pihl, T.

2002-12-01

Wear-resistant thermal spray coatings for sliding wear are hard but brittle (such as carbide and oxide based coatings), which makes them useless under impact loading conditions and sensitive to fatigue. Under extreme conditions of erosive wear (impact loading, high hardness of abrasives, and high velocity of abradant particles), composite coatings ensure optimal properties of hardness and toughness. The article describes tungsten carbide-cobalt (WC-Co) systems and self-fluxing alloys, containing tungsten carbide based hardmetal particles [NiCrSiB-(WC-Co)] deposited by the detonation gun, continuous detonation spraying, and spray fusion processes. Different powder compositions and processes were studied, and the effect of the coating structure and wear parameters on the wear resistance of coatings are evaluated. The dependence of the wear resistance of sprayed and fused coatings on their hardness is discussed, and hardness criteria for coating selection are proposed. The so-called “double cemented” structure of WC-Co based hardmetal or metal matrix composite coatings, as compared with a simple cobalt matrix containing particles of WC, was found optimal. Structural criteria for coating selection are provided. To assist the end user in selecting an optimal deposition method and materials, coating selection diagrams of wear resistance versus hardness are given. This paper also discusses the cost-effectiveness of coatings in the application areas that are more sensitive to cost, and composite coatings based on recycled materials are offered.

Evaluating food additives as antifungal agents against Monilinia fructicola in vitro and in hydroxypropyl methylcellulose-lipid composite edible coatings for plums.

PubMed

Karaca, Hakan; Pérez-Gago, María B; Taberner, Verònica; Palou, Lluís

2014-06-02

Common food preservative agents were evaluated in in vitro tests for their antifungal activity against Monilinia fructicola, the most economically important pathogen causing postharvest disease of stone fruits. Radial mycelial growth was measured in Petri dishes of PDA amended with three different concentrations of the agents (0.01-0.2%, v/v) after 7 days of incubation at 25 °C. Thirteen out of fifteen agents tested completely inhibited the radial growth of the fungus at various concentrations. Among them, ammonium carbonate, ammonium bicarbonate and sodium bicarbonate were the most effective while sodium acetate and sodium formate were the least effective. The effective agents and concentrations were tested as ingredients of hydroxypropyl methylcellulose (HPMC)-lipid edible coatings against brown rot disease on plums previously inoculated with M. fructicola (curative activity). 'Friar' and 'Larry Ann' plums were inoculated with the pathogen, coated with stable edible coatings about 24h later, and incubated at 20 °C and 90% RH. Disease incidence (%) and severity (lesion diameter) were determined after 4, 6, and 8 days of incubation and the 'area under the disease progress stairs' (AUDPS) was calculated. Coatings containing bicarbonates and parabens significantly reduced brown rot incidence in plums, but potassium sorbate, used at 1.0% in the coating formulation, was the most effective agent with a reduction rate of 28.6%. All the tested coatings reduced disease severity to some extent, but coatings containing 0.1% sodium methylparaben or sodium ethylparaben or 0.2% ammonium carbonate or ammonium bicarbonate were superior to the rest, with reduction rates of 45-50%. Overall, the results showed that most of the agents tested in this study had significant antimicrobial activity against M. fructicola and the application of selected antifungal edible coatings is a promising alternative for the control of postharvest brown rot in plums. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of CeO₂ on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding.

PubMed

Chen, Tao; Liu, Defu; Wu, Fan; Wang, Haojun

2017-12-31

To solve the lack of wear resistance of titanium alloys for use in biological applications, various prepared coatings on titanium alloys are often used as wear-resistant materials. In this paper, TiC bioinert coatings were fabricated on Ti6Al4V by laser cladding using mixed TiC and ZrO₂ powders as the basic pre-placed materials. A certain amount of CeO₂ powder was also added to the pre-placed powders to further improve the properties of the TiC coatings. The effects of CeO₂ additive on the phase constituents, microstructures and wear resistance of the TiC coatings were researched in detail. Although the effect of CeO₂ on the phase constituents of the coatings was slight, it had a significant effect on the microstructure and wear resistance of the coatings. The crystalline grains in the TiC coatings, observed by a scanning electron microscope (SEM), were refined due to the effect of the CeO₂. With the increase of CeO₂ additive content in the pre-placed powders, finer and more compact dendrites led to improvement of the micro-hardness and wear resistance of the TiC coatings. Also, 5 wt % content of CeO₂ additive in the pre-placed powders was the best choice for improving the wear properties of the TiC coatings.

Corrosion resistance and mechanical properties of titanium nitride plating on orthodontic wires.

PubMed

Sugisawa, Haruki; Kitaura, Hideki; Ueda, Kyosuke; Kimura, Keisuke; Ishida, Masahiko; Ochi, Yumiko; Kishikawa, Akiko; Ogawa, Saika; Takano-Yamamoto, Teruko

2018-03-30

Titanium nitride (TiN) coating by ion plating has properties such as high hardness, wear resistance, corrosion resistance, and surface lubricity, therefore TiN coating is often used in various dental appliances and materials. In this study, we evaluated the corrosion behaviors and mechanical properties of TiN coated stainless steel (SS) and nickel titanium (Ni-Ti) orthodontic wires prepared by ion plating. TiN coating by ion plating improves the corrosion resistance of orthodontic wires. The corrosion pitting of the TiN coated wire surface become small. The tensile strength and stiffness of SS wire were increased after TiN coating. In contrast, its elastic force, which is a property for Ni-Ti wire, was decreased. In addition, TiN coating provided small friction forces. The low level of friction may increase tooth movement efficiently. Therefore, TiN coated SS wire could be useful for orthodontics treatment.

Performance Evaluation and Modeling of Erosion Resistant Turbine Engine Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Miller, Robert A.; Zhu, Dongming; Kuczmarski, Maria

2008-01-01

The erosion resistant turbine thermal barrier coating system is critical to the rotorcraft engine performance and durability. The objective of this work was to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and thermal gradient environments, thus validating a new thermal barrier coating turbine blade technology for future rotorcraft applications. A high velocity burner rig based erosion test approach was established and a new series of rare earth oxide- and TiO2/Ta2O5- alloyed, ZrO2-based low conductivity thermal barrier coatings were designed and processed. The low conductivity thermal barrier coating systems demonstrated significant improvements in the erosion resistance. A comprehensive model based on accumulated strain damage low cycle fatigue is formulated for blade erosion life prediction. The work is currently aiming at the simulated engine erosion testing of advanced thermal barrier coated turbine blades to establish and validate the coating life prediction models.

The Development of Erosion and Impact Resistant Turbine Airfoil Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2007-01-01

Thermal barrier coatings are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments and extend component lifetimes. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Advanced erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the doped thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion and impact damage mechanisms of the thermal barrier coatings will also be discussed.

Influence of Bond Coat on HVOF-Sprayed Gradient Cermet Coating on Copper Alloy

NASA Astrophysics Data System (ADS)

Ke, Peng; Cai, Fei; Chen, Wanglin; Wang, Shuoyu; Ni, Zhenhang; Hu, Xiaohong; Li, Mingxi; Zhu, Guanghong; Zhang, Shihong

2017-06-01

Coatings are required on mold copper plates to prolong their service life through enhanced hardness, wear resistance, and oxidation resistance. In the present study, NiCr-30 wt.%Cr3C2 ceramic-metallic (cermet) layers were deposited by high velocity oxy-fuel (HVOF) spraying on different designed bond layers, including electroplated Ni, HVOF-sprayed NiCr, and double-decker Ni-NiCr. Annealing was also conducted on the gradient coating (GC) with NiCr bond layer to improve the wear resistance and adhesion strength. Coating microstructure was investigated by scanning electron microscopy and x-ray diffraction analysis. Mechanical properties including microhardness, wear resistance, and adhesion strength of the different coatings were evaluated systematically. The results show that the types of metallic bond layer and annealing process had a significant impact on the mechanical properties of the GCs. The GCs with electroplated Ni bond layer exhibited the highest adhesion strength (about 70 MPa). However, the GC with HVOF-sprayed NiCr bond layer exhibited better wear resistance. The wear resistance and adhesion strength of the coating with NiCr metallic bond layer were enhanced after annealing.

Erythrocyte membrane-coated nanogel for combinatorial antivirulence and responsive antimicrobial delivery against Staphylococcus aureus infection.

PubMed

Zhang, Yue; Zhang, Jianhua; Chen, Wansong; Angsantikul, Pavimol; Spiekermann, Kevin A; Fang, Ronnie H; Gao, Weiwei; Zhang, Liangfang

2017-10-10

We reported an erythrocyte membrane-coated nanogel (RBC-nanogel) system with combinatorial antivirulence and responsive antibiotic delivery for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection. RBC membrane was coated onto the nanogel via a membrane vesicle templated in situ gelation process, whereas the redox-responsiveness was achieved by using a disulfide bond-based crosslinker. We demonstrated that the RBC-nanogels effectively neutralized MRSA-associated toxins in extracellular environment and the toxin neutralization in turn promoted bacterial uptake by macrophages. In intracellular reducing environment, the RBC-nanogels showed an accelerated drug release profile, which resulted in more effective bacterial inhibition. When added to the macrophages infected with intracellular MRSA bacteria, the RBC-nanogels significantly inhibited bacterial growth compared to free antibiotics and non-responsive nanogel counterparts. These results indicate the great potential of the RBC-nanogel system as a new and effective antimicrobial agent against MRSA infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Ni-Fe2O4 nanoparticles as contrast agents for magnetic resonance imaging.

PubMed

Ahmad, Tanveer; Rhee, Ilsu; Hong, Sungwook; Chang, Yongmin; Lee, Jaejun

2011-07-01

Reported herein is the synthesis of a dextran coating on nickel ferrite (Ni-Fe2O4) nanoparticles via chemical coprecipitation. The aqueous solution of the synthesized nanoparticles showed good colloidal stability, and no precipitate was observed 20 months after the synthesis. The coated nanoparticles were found to be cylindrical in shape in the TEM images, and showed a uniform size distribution with an average length and diameter of 17 and 4 nm, respectively. The coated particles were evaluated as potential T1 and T2 contrast agents for MRI. The T1 and T2 relaxations of the hydrogen protons in the water molecules in an aqueous solution of dextran-coated Ni-Fe2O4 nanoparticles were studied. It was found that the T1 relaxivity for the aqueous solution of dextran-coated nanoparticles was slightly greater than that of a commercial Gd-DTPA-BMA contrast agent. The T2 relaxivity, however, was almost twice that of the commercial Gd-DTPA-BMA contrast agent. Animal experimentation also demonstrated that the dextran-coated Ni-Fe2O4 nanoparticles are suitable for use as either T1 or T2 contrast agents in MRI.

Engineered Chimeric Peptides as Antimicrobial Surface Coating Agents toward Infection-Free Implants

PubMed Central

Yazici, Hilal; O'Neill, Mary B.; Kacar, Turgay; Wilson, Brandon R.; Oren, E. Emre; Sarikaya, Mehmet; Tamerler, Candan

2016-01-01

Prevention of bacterial colonization and consequent biofilm formation remains a major challenge in implantable medical devices. Implant-associated infections are not only a major cause of implant failures but also their conventional treatment with antibiotics brings further complications due to the escalation in multidrug resistance to a variety of bacterial species. Owing to their unique properties, antimicrobial peptides (AMPs) have gained significant attention as effective agents to combat colonization of microorganisms. These peptides have been shown to exhibit a wide spectrum of activities with specificity to a target cell while having a low tendency for developing bacterial resistance. Engineering biomaterial surfaces that feature AMP properties, therefore, offer a promising approach to prevent implant infections. Here, we engineered a chimeric peptide with bifunctionality that both forms a robust solid-surface coating while presenting antimicrobial property. The individual domains of the chimeric peptides were evaluated for their solid-binding kinetics to titanium substrate as well as for their antimicrobial properties in solution. The antimicrobial efficacy of the chimeric peptide on the implant material was evaluated in vitro against infection by a variety of bacteria, including Streptococcus mutans, Staphylococcus. epidermidis, and Escherichia coli, which are commonly found in oral and orthopedic implant related surgeries. Our results demonstrate significant improvement in reducing bacterial colonization onto titanium surfaces below the detectable limit. Engineered chimeric peptides with freely displayed antimicrobial domains could be a potential solution for developing infection-free surfaces by engineering implant interfaces with highly reduced bacterial colonization property. PMID:26795060

Engineered Chimeric Peptides as Antimicrobial Surface Coating Agents toward Infection-Free Implants.

PubMed

Yazici, Hilal; O'Neill, Mary B; Kacar, Turgay; Wilson, Brandon R; Oren, E Emre; Sarikaya, Mehmet; Tamerler, Candan

2016-03-02

Prevention of bacterial colonization and consequent biofilm formation remains a major challenge in implantable medical devices. Implant-associated infections are not only a major cause of implant failures but also their conventional treatment with antibiotics brings further complications due to the escalation in multidrug resistance to a variety of bacterial species. Owing to their unique properties, antimicrobial peptides (AMPs) have gained significant attention as effective agents to combat colonization of microorganisms. These peptides have been shown to exhibit a wide spectrum of activities with specificity to a target cell while having a low tendency for developing bacterial resistance. Engineering biomaterial surfaces that feature AMP properties, therefore, offer a promising approach to prevent implant infections. Here, we engineered a chimeric peptide with bifunctionality that both forms a robust solid-surface coating while presenting antimicrobial property. The individual domains of the chimeric peptides were evaluated for their solid-binding kinetics to titanium substrate as well as for their antimicrobial properties in solution. The antimicrobial efficacy of the chimeric peptide on the implant material was evaluated in vitro against infection by a variety of bacteria, including Streptococcus mutans, Staphylococcus. epidermidis, and Escherichia coli, which are commonly found in oral and orthopedic implant related surgeries. Our results demonstrate significant improvement in reducing bacterial colonization onto titanium surfaces below the detectable limit. Engineered chimeric peptides with freely displayed antimicrobial domains could be a potential solution for developing infection-free surfaces by engineering implant interfaces with highly reduced bacterial colonization property.

Corrosion-resistant antifretting coating for the protection of blade locking pieces in GTE compressors and fans

NASA Astrophysics Data System (ADS)

Muboyadzhyan, S. A.; Gorlov, D. S.; Egorova, L. P.; Bulavintseva, E. E.

2014-09-01

The properties of a corrosion-resistant antifretting coating on EP866Sh steel and VT8M-1 titanium alloy samples are studied. The results of corrosion resistance, heat resistance, fretting resistance, long-term strength, and high-cycle fatigue tests and the results of physical metallurgy and metallographic investigations of the samples with the coating before and after the tests are presented.

The effects of RE and Si on the microstructure and corrosion resistance of Zn-6Al-3Mg hot dip coating

NASA Astrophysics Data System (ADS)

Li, Shiwei; Gao, Bo; Yin, Shaohua; Tu, Ganfeng; Zhu, Guanglin; Sun, Shuchen; Zhu, Xiaoping

2015-12-01

The effects of Si and RE on the microstructure and corrosion resistance of Zn-6Al-3Mg coating (ZAM) have been investigated. Surface morphology observations of the coating and corrosion products reveal that the additions of Si and rare earth metals (RES) improve the microstructural homogeneity of ZAMSR coating and stability of corrosion products formed on ZAMSR coating. Moreover, only uniform corrosion occurs in ZAMSR coating during the corrosion test, while intergranular corrosion and pitting occur in ZAM. As a result, the corrosion resistance of ZAM coating is improved by the additions of Si and RES.

An environmentally compliant cerium-based conversion coating for aluminum protection

NASA Astrophysics Data System (ADS)

Lin, Xuan

Chromate conversion coatings have been extensively used in the aircraft industry for the corrosion protection of aluminum alloys. Unfortunately, hexavalent chromium, which is a primary component in the chromating process, is a confirmed carcinogen. Because of rising remediation and disposal costs caused by increasingly strict regulations, the replacement of the traditional chromate conversion process is becoming a top priority in the metal finishing industry. This research focused on the electrodeposition of cerium-based coatings on 7075-T6 aluminum alloy in an electrolyte containing a cerium salt, an oxidizing agent and an organic solvent. The cerium-rich deposits were characterized by phase composition, oxidation state, coating thickness, surface morphology, deposition mechanism and polarization behavior. Chemical and electrochemical tests were utilized to compare the corrosion resistance between cerium-based coatings and chromate conversion coatings. To characterize and simulate the deposition process, a variety of approaches were utilized to study the oxidation states of cerium in various soluble and precipitated forms as a function of hydrogen peroxide and electrolyte pH. The pH ranges where the oxidation and reduction reactions dominate were determined. Further studies were performed to optimize the corrosion performance of cerium-based coatings and to understand the effects of electrolyte constituents and deposition parameters. The optimum levels for these variables were identified. A patent disclosure on the cerium-based coating process was made to the University of Missouri-Rolla and has now been officially filed with the U.S. Patent Office.

Recent developments in high temperature coatings for gas turbine airfoils

NASA Technical Reports Server (NTRS)

Goward, G. W.

1983-01-01

The importance of coatings for hot section airfoils has increased with the drive for more cost-effective use of fuel in a wide variety of gas turbine engines. Minor additions of silicon have been found to appreciably increase the oxidation resistance of plasma-sprayed NiCoCrAlY coatings on a single crystal nickel-base superalloy. Increasing the chromium content of MCrAlY coatings substantially increases the resistance to acidic (Na2SO4-SO3) hot corrosion at temperatures of about 1300 F (704 C) but gives no significant improvement beyond contemporary coatings in the range of 1600 F (871 C). Surface enrichment of MCrAlY coatings with silicon also gives large increases in resistance to acidic hot corrosion in the 1300 F region. The resistance to the thermal stress-induced spalling of zirconia-based thermal barrier coatings has been improved by lowering coating stresses with segmented structures and by controlling the substrate temperature during coating fabrication.

Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

2009-05-01

Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.

In-vitro biodegradation and corrosion-assisted cracking of a coated magnesium alloy in modified-simulated body fluid.

PubMed

Jafari, Sajjad; Singh Raman, R K

2017-09-01

A calcium phosphate coating was directly synthesized on AZ91D magnesium (Mg) alloy. Resistance of this coating to corrosion in a modified-simulated body fluid (m-SBF) was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Mechanical properties of the bare and coated alloy were investigated using slow strain rate tensile (SSRT) and fatigue testing in air and m-SBF. Very little is reported in the literature on human-body-fluid-assisted cracking of Mg alloys, viz., resistance to corrosion fatigue (CF) and stress corrosion cracking (SCC). This study has a particular emphasis on the effect of bio-compatible coatings on mechanical and electrochemical degradations of Mg alloys for their applications as implants. The results suggest the coating to improve the general as well as pitting corrosion resistance of the alloy. The coating also provides visible improvement in resistance to SCC, but little improvement in CF resistance. This is explained on the basis of pitting behaviour in the presence and absence of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

2D Heterostructure coatings of hBN-MoS2 layers for corrosion resistance

NASA Astrophysics Data System (ADS)

Vandana, Sajith; Kochat, Vidya; Lee, Jonghoon; Varshney, Vikas; Yazdi, Sadegh; Shen, Jianfeng; Kosolwattana, Suppanat; Vinod, Soumya; Vajtai, Robert; Roy, Ajit K.; Sekhar Tiwary, Chandra; Ajayan, P. M.

2017-02-01

Heterostructures of atomically thin 2D materials could have improved physical, mechanical and chemical properties as compared to its individual components. Here we report, the effect of heterostructure coatings of hBN and MoS2 on the corrosion behavior as compared to coatings employing the individual 2D layer compositions. The poor corrosion resistance of MoS2 (widely used as wear resistant coating) can be improved by incorporating hBN sheets. Depending on the atomic stacking of the 2D sheets, we can further engineer the corrosion resistance properties of these coatings. A detailed spectroscopy and microscopy analysis has been used to characterize the different combinations of layered coatings. Detailed DFT based calculation reveals that the effect on the electrical properties due to atomic stacking is one of the major reasons for the improvement seen in corrosion resistance.

Resistively heated shape memory polymer device

DOEpatents

Marion, III, John E.; Bearinger, Jane P.; Wilson, Thomas S.; Maitland, Duncan J.

2017-09-05

A resistively heated shape memory polymer device is made by providing a rod, sheet or substrate that includes a resistive medium. The rod, sheet or substrate is coated with a first shape memory polymer providing a coated intermediate unit. The coated intermediate unit is in turn coated with a conductive material providing a second intermediate unit. The second coated intermediate unit is in turn coated with an outer shape memory polymer. The rod, sheet or substrate is exposed and an electrical lead is attached to the rod, sheet or substrate. The conductive material is exposed and an electrical lead is attached to the conductive material.

Resistively heated shape memory polymer device

DOEpatents

Marion, III, John E.; Bearinger, Jane P.; Wilson, Thomas S.; Maitland, Duncan J.

2016-10-25

A resistively heated shape memory polymer device is made by providing a rod, sheet or substrate that includes a resistive medium. The rod, sheet or substrate is coated with a first shape memory polymer providing a coated intermediate unit. The coated intermediate unit is in turn coated with a conductive material providing a second intermediate unit. The second coated intermediate unit is in turn coated with an outer shape memory polymer. The rod, sheet or substrate is exposed and an electrical lead is attached to the rod, sheet or substrate. The conductive material is exposed and an electrical lead is attached to the conductive material.

RETRACTED: Chemical densification of plasma sprayed yttria stabilized zirconia (YSZ) coatings for high temperature wear and corrosion resistance

NASA Astrophysics Data System (ADS)

Ye, Yaping; Fehr, Karl Thomas; Faulstich, Martin; Wolf, Gerhard

2012-12-01

Plasma-sprayed yttria stabilized zirconia (YSZ) ceramic coatings have been widely used as wear- and corrosion-resistant coatings in high temperature applications and an aggressive environment due to their high hardness, wear resistance, heat and chemical resistance, and low thermal conductivity. The highly porous structure of plasma-sprayed ceramic coatings and their poor adhesion to the substrate usually lead to the coating degradation and failure. In this study, a two-layer system consisting of atmospheric plasma-sprayed 8 wt.% yttria-stabilized zirconia (8YSZ) and Ni-based alloy coatings was post-treated by means of a novel chemical sealing process at moderate temperatures of 600-800 °C. Microstructure characteristics of the YSZ coatings were studied using an electron probe micro-analyzer (EPMA). Results revealed that the ceramic top coat was densified by the precipitated zirconia in the open pores. Therefore, the sealed YSZ coatings exhibit reduced porosity, higher hardness and a better adhesion onto the bond coat. The mechanisms for the sealing process were also proposed.

Solid-water detoxifying reagents for chemical and biological agents

DOEpatents

Hoffman, Dennis M [Livermore, CA; Chiu, Ing Lap [Castro Valley, CA

2006-04-18

Formation of solid-water detoxifying reagents for chemical and biological agents. Solutions of detoxifying reagent for chemical and biological agents are coated using small quantities of hydrophobic nanoparticles by vigorous agitation or by aerosolization of the solution in the presence of the hydrophobic nanoparticles to form a solid powder. For example, when hydrophobic fumed silica particles are shaken in the presence of IN oxone solution in approximately a 95:5-weight ratio, a dry powder results. The hydrophobic silica forms a porous coating of insoluble fine particles around the solution. Since the chemical or biological agent tends to be hydrophobic on contact with the weakly encapsulated detoxifying solution, the porous coating breaks down and the detoxifying reagent is delivered directly to the chemical or biological agent for maximum concentration at the point of need. The solid-water (coated) detoxifying solutions can be blown into contaminated ventilation ducting or other difficult to reach sites for detoxification of pools of chemical or biological agent. Once the agent has been detoxified, it can be removed by flushing the area with air or other techniques.

Effect of CeO2 on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding

PubMed Central

Wang, Haojun

2017-01-01

To solve the lack of wear resistance of titanium alloys for use in biological applications, various prepared coatings on titanium alloys are often used as wear-resistant materials. In this paper, TiC bioinert coatings were fabricated on Ti6Al4V by laser cladding using mixed TiC and ZrO2 powders as the basic pre-placed materials. A certain amount of CeO2 powder was also added to the pre-placed powders to further improve the properties of the TiC coatings. The effects of CeO2 additive on the phase constituents, microstructures and wear resistance of the TiC coatings were researched in detail. Although the effect of CeO2 on the phase constituents of the coatings was slight, it had a significant effect on the microstructure and wear resistance of the coatings. The crystalline grains in the TiC coatings, observed by a scanning electron microscope (SEM), were refined due to the effect of the CeO2. With the increase of CeO2 additive content in the pre-placed powders, finer and more compact dendrites led to improvement of the micro-hardness and wear resistance of the TiC coatings. Also, 5 wt % content of CeO2 additive in the pre-placed powders was the best choice for improving the wear properties of the TiC coatings. PMID:29301218

Assessment of thermal spray coatings for wear and abrasion resistance applications

NASA Astrophysics Data System (ADS)

Karode, Ishaan Nitin

Thermal spray cermet and metallic coatings are extensively used for wear, abrasion and corrosion control in a variety of industries. The first part of the thesis focuses mainly on testing of sand erosion resistance of thermal spray coatings on carbon composites used in the manufacture of helicopter rotor blades. The test set-up employed is a sand blasting machine and is an effort to duplicate the in-flight conditions especially those encountered in hot arid conditions. The technique adopted follows the Department of Defence test method standard. Carbon Composites have excellent stiffness, strength and low weight/density. The strength to weight ratio is high. Hence, these are used in aerospace applications to a large extent. However, the biggest problem encountered with carbon composites is its low abrasion resistance as its surface is very weak. Hence, thermal spray coatings are used to improve the surface properties of CFRP. Zinc bond coats and WC-Co coatings were tested. However, high amount of thermal stresses were developed between the substrate and the coating due to large differences in the CTE's of the both, leading to high mass losses within two minutes and just 130 grams of sand sprayed on to the coatings with the sand blasting machine built; and hence the coatings with CC as a substrate could not qualify for the application. The second part of the thesis focuses on the assessment of different thermal spray coatings used for manufacture of mechanical seals in pumps and analyze the best coating material for the wear resistance application through detail quantification of material loss by block-on-ring test set-up. A machine based on Block-on-ring test set-up following ASTM G77 (Measurement of Adhesive wear resistance of thermal spray coatings) standards was built to duplicate the pump conditions. Thermally sprayed coated materials were tested in different conditions (Load, time, abrasive). WC-Co had the highest wear resistance (lower volume losses) and proved to be the best coating amongst all the other ones followed by Cr2O3 and Al2O3 in deionized water. In the presence of abrasive alumina slurry WC-Co offered the highest abrasive resistance with the lowest volume losses followed by Al2O3 and Cr2O3. In both the testing conditions B4C coating showed lower wear/abrasion resistance giving the highest volume losses.

Preparation and characterization of coating sodium trisilicate (Na2O.nSiO2) at calcium carbonate (CaCO3) for blowing agent in Mg alloy foam

NASA Astrophysics Data System (ADS)

Erryani, Aprilia; Lestari, Franciska Pramuji; Annur, Dhyah; Kartika, Ika

2018-05-01

The role of blowing agent in the manufacture of porous metal alloys is very important to produce the desired pore. The thermal stability and speed of foam formation have an effect on the resulting pore structure. In porous metal alloys, uniformity of size and pore deployment are the main determinants of the resulting alloys. The coating process of calcium carbonate (CaCO3) has been done using Sodium trisilicate solution by sol-gel method. Foaming agent was pretreated by coating SiO2 passive layer on the surface of CaCO3. This coating aims to produce a more stable blowing agent so that the foaming process can produce a more uniform pore size. The microstructure of the SiO2 passive was observed using Scanning Electron Microscope (SEM) equipped by Energy Dispersive X-Ray Spectrometer (EDS) mapping. The results showed coating CaCO3 using sodium trisilicate was successfully done creating a passive layer of SiO2 on the surface of CaCO3. By the coating process, the thermal stability of coated CaCO3 increased compared to uncoated CaCO3.

Antithrombogenic Polymer Coating.

DOEpatents

Huang, Zhi Heng; McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

2003-01-21

An article having a non-thrombogenic surface and a process for making the article are disclosed. The article is formed by (i) coating a polymeric substrate with a crosslinked chemical combination of a polymer having at least two amino substituted side chains, a crosslinking agent containing at least two crosslinking functional groups which react with amino groups on the polymer, and a linking agent containing a first functional group which reacts with a third functional group of the crosslinking agent, and (ii) contacting the coating on the substrate with an antithrombogenic agent which covalently bonds to a second functional group of the linking agent. In one example embodiment, the polymer is a polyamide having amino substituted alkyl chains on one side of the polyamide backbone, the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl, the linking agent is a polyhydrazide and the antithrombogenic agent is heparin.

Are opthalmic hydrophobic coatings useful for astronomical optics?

NASA Astrophysics Data System (ADS)

Schwab, Christian; Phillips, Andrew C.

2010-07-01

Astronomical optics are often exposed to moisture and dust in observatory environments, which frequently compromises their high-performance coatings. Suitable protective layers to resist dust and moisture accumulation would be extremely advantageous, but have received scant attention thus far. Hydrophobic and scratch-resistant coatings, developed primarily for opthalmic use, exhibit several attractive properties for astronomical optics. We examine the properties of one such coating and its applicability to astronomical mirrors and lenses. This includes efficiency of dust removal, abrasion resistance, moisture resistance, ease of stripping, and transmission across a wide wavelength range.

Thermal-electrical properties and resistance stability of silver coated yarns

NASA Astrophysics Data System (ADS)

Li, Yafang; Liu, Hao; Li, Xiaojiu

2017-03-01

Thermal-electrical properties and resistance stability of silver yarns was researched to evaluate the performance be a heating element. Three samples of silver coated yarns with different linear density and electrical resistivity, which obtained by market. Silver coated yarns were placed at the high temperature condition for ageing. The electrical resistances of yarns were increased with the ageing process. The infrared photography instrument was used to measurement the temperature variation of silver coated yarns by applied different current on. The result shows that the temperature rise with the power increases.

Corrosion resistance of the microarc oxidation coatings prepared on magnesium alloy

NASA Astrophysics Data System (ADS)

Lv, Ying; Li, Jun Gang; Wu, Ming Zhong; Ma, Zhen; Zhang, Jing Qiang; Wang, Le Le

2018-06-01

Ceramic coatings were prepared on the surface of AZ91D magnesium alloy by microarc oxidation technology. The effects of different voltages on morphology, phase composition and thickness of the coatings were characterized by SEM and XRD. The corrosion resistance of the coatings was measured by electrochemical workstation. Results indicated that the microarc oxidation coatings prepared in sodium silicate electrolyte exhibited porous surface and mainly comprised MgO, Mg2SiO4 and a small amount of MgAl2O4. The thickness of the oxide coatings increased rapidly with the increase of voltage. The coating prepared at 400V voltage had good electrochemical corrosion resistance in 3.5wt% NaCl solution.

Oxidation resistant nanocrystalline MCrAl(Y) coatings and methods of forming such coatings

DOEpatents

Cheruvu, Narayana S.; Wei, Ronghua

2014-07-29

The present disclosure relates to an oxidation resistant nanocrystalline coating and a method of forming an oxidation resistant nanocrystalline coating. An oxidation resistant coating comprising an MCrAl(Y) alloy may be deposited on a substrate, wherein M, includes iron, nickel, cobalt, or combinations thereof present greater than 50 wt % of the MCrAl(Y) alloy, chromium is present in the range of 15 wt % to 30 wt % of the MCrAl(Y) alloy, aluminum is present in the range of 6 wt % to 12 wt % of the MCrAl(Y) alloy and yttrium, is optionally present in the range of 0.1 wt % to 0.5 wt % of the MCrAl(Y) alloy. In addition, the coating may exhibit a grain size of 200 nm or less as deposited.

Method for applying photographic resists to otherwise incompatible substrates

NASA Technical Reports Server (NTRS)

Fuhr, W. (Inventor)

1981-01-01

A method for applying photographic resists to otherwise incompatible substrates, such as a baking enamel paint surface, is described wherein the uncured enamel paint surface is coated with a non-curing lacquer which is, in turn, coated with a partially cured lacquer. The non-curing lacquer adheres to the enamel and a photo resist material satisfactorily adheres to the partially cured lacquer. Once normal photo etching techniques are employed the lacquer coats can be easily removed from the enamel leaving the photo etched image. In the case of edge lighted instrument panels, a coat of uncured enamel is placed over the cured enamel followed by the lacquer coats and the photo resists which is exposed and developed. Once the etched uncured enamel is cured, the lacquer coats are removed leaving an etched panel.

Materials for Advanced Turbine Engines (MATE). Project 4: Erosion resistant compressor airfoil coating

NASA Technical Reports Server (NTRS)

Rashid, J. M.; Freling, M.; Friedrich, L. A.

1987-01-01

The ability of coatings to provide at least a 2X improvement in particulate erosion resistance for steel, nickel and titanium compressor airfoils was identified and demonstrated. Coating materials evaluated included plasma sprayed cobalt tungsten carbide, nickel carbide and diffusion applied chromium plus boron. Several processing parameters for plasma spray processing and diffusion coating were evaluated to identify coating systems having the most potential for providing airfoil erosion resistance. Based on laboratory results and analytical evaluations, selected coating systems were applied to gas turbine blades and evaluated for surface finish, burner rig erosion resistance and effect on high cycle fatigue strength. Based on these tests, the following coatings were recommended for engine testing: Gator-Gard plasma spray 88WC-12Co on titanium alloy airfoils, plasma spray 83WC-17Co on steel and nickel alloy airfoils, and Cr+B on nickel alloy airfoils.

The one-step electroposition of superhydrophobic surface on AZ31 magnesium alloy and its time-dependence corrosion resistance in NaCl solution

NASA Astrophysics Data System (ADS)

Zhong, Yuxing; Hu, Jin; Zhang, Yufen; Tang, Shawei

2018-01-01

A calcium myristic superhydrophobicity coating with a hierarchical micro-nanostructure was fabricated on AZ31 magnesium alloy by one-step electroposition. The effects of deposition time on the coating structure, such as morphology, thickness, wettability and phase composition of the coating were studied. The corrosion behavior of the coated samples in 3.5% NaCl solution was also investigated and the corrosion mechanism was discussed. It was found that the deposition time has a visible effect on the morphology, thickness and wettability, which distinctly affects the corrosion resistance of coatings. The corrosion resistance of the coating gradually decreases with the increase in the immersion time due to the disappearance of the air layer which exists on the coating surface. The superhydrophobic surfaces present the temporal limitations to the corrosion resistance of AZ31 magnesium alloy.

Chemical resistance and cleanability of glazed surfaces

NASA Astrophysics Data System (ADS)

Hupa, Leena; Bergman, Roger; Fröberg, Linda; Vane-Tempest, Stina; Hupa, Mikko; Kronberg, Thomas; Pesonen-Leinonen, Eija; Sjöberg, Anna-Maija

2005-06-01

Adhesion of soil on glazed surfaces and their cleanability depends on chemical composition, phase composition, and roughness of the surface. The surface can be glossy consisting mainly of a smooth glassy phase. A matt and rough surface consists of a glassy phase and one or more crystalline phases. The origin and composition of the crystalline phases affect the chemical resistance and the cleanability of the surface. Fifteen experimental glossy and matt glazes were soaked in a slightly alkaline cleaning agent solution. The surfaces were spin-coated with sebum, i.e. a soil component typical for sanitary facilities. After wiping out the soil film in a controlled manner, the surface conditions and the soil left were evaluated with colour measurements, SEM/EDXA and COM. The results show that wollastonite-type crystals in the glaze surfaces were attacked in aqueous solutions containing typical cleaning agents. This corrosion led to significant decrease in the cleanability of the surface. The other crystal types observed, i.e. diopside and quartz crystals were not corroded, and the cleanability of glazes containing only these crystals was not changed in the cleaning agent exposures. Also the glassy phase was found to be attacked in some formulations leading to a somewhat decreased cleanability. The repeated soiling and cleaning procedures indicated that soil is accumulated on rough surfaces and surfaces which were clearly corroded by the cleaning agent.

Microstructure and tribological properties of in situ synthesized TiC, TiN, and SiC reinforced Ti 3Al intermetallic matrix composite coatings on pure Ti by laser cladding

NASA Astrophysics Data System (ADS)

Pu, Yuping; Guo, Baogang; Zhou, Jiansong; Zhang, Shitang; Zhou, Huidi; Chen, Jianmin

2008-12-01

TiC, TiN, and SiC reinforced Ti 3Al intermetallic matrix composite (IMC) coatings were in situ synthesized on a pure Ti substrate by laser cladding. It was found that the surface hardness and the wear resistance of the Ti 3Al coating were improved by the formation of these Ti 3Al IMC coatings. The surface hardness and the wear resistance of the TiC/Ti 3Al IMC coatings increased with the increasing volume fraction of TiC powder. Under the same dry sliding test conditions, the wear resistance of TiC, TiN, and SiC reinforced Ti 3Al IMC coatings with 40 vol.% reinforced powder was in the following order: TiN/Ti 3Al IMC coating > TiC/Ti 3Al IMC coating > SiC/Ti 3Al IMC coating. It should be noted that both the TiC/Ti 3Al IMC coating with 40 vol.% TiC powder and the TiN/Ti 3Al coating with 40 vol.% TiN powder showed excellent wear resistance under 5 N normal load.

Effect of manufacturing process sequence on the corrosion resistance characteristics of coated metallic bipolar plates

NASA Astrophysics Data System (ADS)

Dur, Ender; Cora, Ömer Necati; Koç, Muammer

2014-01-01

Metallic bipolar plate (BPP) with high corrosion and low contact resistance, durability, strength, low cost, volume, and weight requirements is one of the critical parts of the PEMFC. This study is dedicated to understand the effect of the process sequence (manufacturing then coating vs. coating then manufacturing) on the corrosion resistance of coated metallic bipolar plates. To this goal, three different PVD coatings (titanium nitride (TiN), chromium nitride (CrN), zirconium nitride (ZrN)), with three thicknesses, (0.1, 0.5, 1 μm) were applied on BPPs made of 316L stainless steel alloy before and after two types of manufacturing (i.e., stamping or hydroforming). Corrosion test results indicated that ZrN coating exhibited the best corrosion protection while the performance of TiN coating was the lowest among the tested coatings and thicknesses. For most of the cases tested, in which coating was applied before manufacturing, occurrence of corrosion was found to be more profound than the case where coating was applied after manufacturing. Increasing the coating thickness was found to improve the corrosion resistance. It was also revealed that hydroformed BPPs performed slightly better than stamped BPPs in terms of the corrosion behavior.

Antibiofouling polymer-coated gold nanoparticles as a contrast agent for in vivo X-ray computed tomography imaging.

PubMed

Kim, Dongkyu; Park, Sangjin; Lee, Jae Hyuk; Jeong, Yong Yeon; Jon, Sangyong

2007-06-20

Current computed tomography (CT) contrast agents such as iodine-based compounds have several limitations, including short imaging times due to rapid renal clearance, renal toxicity, and vascular permeation. Here, we describe a new CT contrast agent based on gold nanoparticles (GNPs) that overcomes these limitations. Because gold has a higher atomic number and X-ray absorption coefficient than iodine, we expected that GNPs can be used as CT contrast agents. We prepared uniform GNPs ( approximately 30 nm in diameter) by general reduction of HAuCl4 by boiling with sodium citrate. The resulting GNPs were coated with polyethylene glycol (PEG) to impart antibiofouling properties, which extends their lifetime in the bloodstream. Measurement of the X-ray absorption coefficient in vitro revealed that the attenuation of PEG-coated GNPs is 5.7 times higher than that of the current iodine-based CT contrast agent, Ultravist. Furthermore, when injected intravenously into rats, the PEG-coated GNPs had a much longer blood circulation time (>4 h) than Ultravist (<10 min). Consequently, CT images of rats using PEG-coated GNPs showed a clear delineation of cardiac ventricles and great vessels. On the other hand, relatively high levels of GNPs accumulated in the spleen and liver, which contain phagocytic cells. Intravenous injection of PEG-coated GNPs into hepatoma-bearing rats resulted in a high contrast ( approximately 2-fold) between hepatoma and normal liver tissue on CT images. These results suggest that PEG-coated GNPs can be useful as a CT contrast agent for a blood pool and hepatoma imaging.

Soft plasma electrolysis with complex ions for optimizing electrochemical performance

NASA Astrophysics Data System (ADS)

Kamil, Muhammad Prisla; Kaseem, Mosab; Ko, Young Gun

2017-03-01

Plasma electrolytic oxidation (PEO) was a promising surface treatment for light metals to tailor an oxide layer with excellent properties. However, porous coating structure was generally exhibited due to excessive plasma discharges, restraining its performance. The present work utilized ethylenediaminetetraacetic acid (EDTA) and Cu-EDTA complexing agents as electrolyte additives that alter the plasma discharges to improve the electrochemical properties of Al-1.1Mg alloy coated by PEO. To achieve this purpose, PEO coatings were fabricated under an alternating current in silicate electrolytes containing EDTA and Cu-EDTA. EDTA complexes were found to modify the plasma discharging behaviour during PEO that led to a lower porosity than that without additives. This was attributed to a more homogeneous electrical field throughout the PEO process while the coating growth would be maintained by an excess of dissolved Al due to the EDTA complexes. When Cu-EDTA was used, the number of discharge channels in the coating layer was lower than that with EDTA due to the incorporation of Cu2O and CuO altering the dielectric behaviour. Accordingly, the sample in the electrolyte containing Cu-EDTA constituted superior corrosion resistance to that with EDTA. The electrochemical mechanism for excellent corrosion protection was elucidated in the context of equivalent circuit model.

Soft plasma electrolysis with complex ions for optimizing electrochemical performance

PubMed Central

Kamil, Muhammad Prisla; Kaseem, Mosab; Ko, Young Gun

2017-01-01

Plasma electrolytic oxidation (PEO) was a promising surface treatment for light metals to tailor an oxide layer with excellent properties. However, porous coating structure was generally exhibited due to excessive plasma discharges, restraining its performance. The present work utilized ethylenediaminetetraacetic acid (EDTA) and Cu-EDTA complexing agents as electrolyte additives that alter the plasma discharges to improve the electrochemical properties of Al-1.1Mg alloy coated by PEO. To achieve this purpose, PEO coatings were fabricated under an alternating current in silicate electrolytes containing EDTA and Cu-EDTA. EDTA complexes were found to modify the plasma discharging behaviour during PEO that led to a lower porosity than that without additives. This was attributed to a more homogeneous electrical field throughout the PEO process while the coating growth would be maintained by an excess of dissolved Al due to the EDTA complexes. When Cu-EDTA was used, the number of discharge channels in the coating layer was lower than that with EDTA due to the incorporation of Cu2O and CuO altering the dielectric behaviour. Accordingly, the sample in the electrolyte containing Cu-EDTA constituted superior corrosion resistance to that with EDTA. The electrochemical mechanism for excellent corrosion protection was elucidated in the context of equivalent circuit model. PMID:28281672

Oxidation-resistant silicide coating applied to columbium alloy screen

NASA Technical Reports Server (NTRS)

Torgerson, R. T.

1971-01-01

Coated screens withstand temperature cycling in special transpiration-cooling systems and provide porous surface that is effective at temperatures well above those limiting superalloy screen efficiency. Thickness of coating depends on time, temperature and activator concentration. Coatings are uniform and resistant to thermal cycling.

Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2012-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

Effects of Voltage on Microstructure and Corrosion Resistance of Micro-arc Oxidation Ceramic Coatings Formed on KBM10 Magnesium Alloy

NASA Astrophysics Data System (ADS)

Lu, J. P.; Cao, G. P.; Quan, G. F.; Wang, C.; Zhuang, J. J.; Song, R. G.

2018-01-01

Micro-arc oxidation (MAO) coatings on KBM10 magnesium alloy were prepared in an electrolyte system with sodium silicate, potassium hydroxide, sodium tungstate, and citric acid. The effects of voltage on the microstructure and corrosion resistance of MAO coatings were studied using stereoscopic microscopy, scanning electron microscopy, x-ray diffraction, scratch tests, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results showed that the roughness of the MAO coatings, diameter, and number of pores increase with the increase in voltage. The coating formed at the voltage of 350 V exhibited the best adhesive strength when evaluated by the automatic scratch tester. The coatings were mainly composed of MgO, MgWO4, and Mg2SiO4, and the content of Mg2SiO4 increased with the increase in voltage. The corrosion resistance of MAO coatings could be improved by changing the applied voltage, and the best corrosion resistance of MAO coating was observed at the voltage of 350 V.

Coated metal sintering carriers for fuel cell electrodes

DOEpatents

Donelson, Richard; Bryson, E. S.

1998-01-01

A carrier for conveying components of a fuel cell to be sintered through a sintering furnace. The carrier comprises a metal sheet coated with a water-based carbon paint, the water-based carbon paint comprising water, powdered graphite, an organic binder, a wetting agent, a dispersing agent and a defoaming agent.

Investigations of Nanocrystalline Alloy Electrospark Coating Made of Nanocrystalline Alloy Based on 5БДCP Ferrum

NASA Astrophysics Data System (ADS)

Kolomeichenko, A. V.; Kuznetsov, I. S.; Izmaylov, A. Yu; Solovyev, R. Yu; Sharifullin, S. N.

2017-09-01

The article describes the properties of wear resistant electrospark coating made of nanocrystalline alloy of type 5БДCP (Finemet). It is proved that electrospark coating has nanocrystalline structure which is like amorphous matrix with nanocrystals α - Fe. Coating thickness is 33 μm, micro-hardness is 8461 - 11357 MPa, wear resistance is 0,55×104s/g. Coating ofnanocrystalline alloy of type 5БДCP can be used to increase wear resistance of machinery working surfaces.

Effect of basalt fibres reinforcement and aluminum trihydrate on the thermal properties of intumescent fire retardant coatings

NASA Astrophysics Data System (ADS)

Yasir, Muhammad; Amir, Norlaili Binti; Ahmad, Faiz; Syahirah Rodzhan, N.

2017-08-01

This research is carried out in order to study the synergistic effect of aluminium trihydrate and basalt fibres on the properties of fire resistant intumescent coatings. Intumescent fire retardant coatings were developed using different flame retardants such as ammonium polyphosphate, expandable graphite, melamine and boric acid. These flame retardants were bound together with the help of epoxy binder along with curing agent. Furthermore, individual and combinations of aluminium trihydrate and basalt fibres was incorporated in the formulations to analyse mechanical and chemical properties of the coatings. Char expansion was observed using furnace test, thermogravimetric analysis was used to determine residual weight, X-Ray Diffraction was performed to investigate compounds present in the char, shear test was conducted to determine char strength and scanning electron microscopy analysis was performed to observe morphology of the burnt char. From the microscopic investigation it was concluded that the dense structure of the char increased the char integrity by adding basalt and aluminium trihydrate as fillers. X-Ray Diffraction results shows the presence boron phosphate, and boric acid which enhanced the thermal performance of the coating up to 800°C. From the Thermogravimetric analysis it was concluded that the residual weight of the char was increased up to 34.9 % for IC-B2A4 which enhanced thermal performance of intumescent coating.

Organoselenium coating on cellulose inhibits the formation of biofilms by Pseudomonas aeruginosa and Staphylococcus aureus.

PubMed

Tran, Phat L; Hammond, Adrienne A; Mosley, Thomas; Cortez, Janette; Gray, Tracy; Colmer-Hamood, Jane A; Shashtri, Mayank; Spallholz, Julian E; Hamood, Abdul N; Reid, Ted W

2009-06-01

Among the most difficult bacterial infections encountered in treating patients are wound infections, which may occur in burn victims, patients with traumatic wounds, necrotic lesions in people with diabetes, and patients with surgical wounds. Within a wound, infecting bacteria frequently develop biofilms. Many current wound dressings are impregnated with antimicrobial agents, such as silver or antibiotics. Diffusion of the agent(s) from the dressing may damage or destroy nearby healthy tissue as well as compromise the effectiveness of the dressing. In contrast, the antimicrobial agent selenium can be covalently attached to the surfaces of a dressing, prolonging its effectiveness. We examined the effectiveness of an organoselenium coating on cellulose discs in inhibiting Pseudomonas aeruginosa and Staphylococcus aureus biofilm formation. Colony biofilm assays revealed that cellulose discs coated with organoselenium completely inhibited P. aeruginosa and S. aureus biofilm formation. Scanning electron microscopy of the cellulose discs confirmed these results. Additionally, the coating on the cellulose discs was stable and effective after a week of incubation in phosphate-buffered saline. These results demonstrate that 0.2% selenium in a coating on cellulose discs effectively inhibits bacterial attachment and biofilm formation and that, unlike other antimicrobial agents, longer periods of exposure to an aqueous environment do not compromise the effectiveness of the coating.

Improvements in Microstructure and Wear Resistance of Plasma-Sprayed Fe-Based Amorphous Coating by Laser-Remelting

NASA Astrophysics Data System (ADS)

Jiang, Chaoping; Chen, Hong; Wang, Gui; Chen, Yongnan; Xing, Yazhe; Zhang, Chunhua; Dargusch, Matthew

2017-04-01

Amorphous coating technology is an attractive way of taking advantage of the superior properties of amorphous alloys for structural applications. However, the limited bonds between splats within the plasma-sprayed coatings result in a typically lamellar and porous coating structure. To overcome these limitations, the as-sprayed coating was treated by a laser-remelting process. The microstructure and phase composition of two coatings were analyzed using scanning electron microscopy with energy-dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction. The wear resistance of the plasma-sprayed coating and laser-remelted coating was studied comparatively using a pin-on-disc wear test under dry friction conditions. It was revealed that the laser-remelted coating exhibited better wear resistance because of its defect-free and amorphous-nanocrystalline composited structure.

Integrating high electrical conductivity and photocatalytic activity in cotton fabric by cationizing for enriched coating of negatively charged graphene oxide.

PubMed

Sahito, Iftikhar Ali; Sun, Kyung Chul; Arbab, Alvira Ayoub; Qadir, Muhammad Bilal; Jeong, Sung Hoon

2015-10-05

Electroconductive textiles have attended tremendous focus recently and researchers are making efforts to increase conductivity of e-textiles, in order to increase the use of such flexible and low cost textile materials. In this study, surface conductivity and photo catalytic activity of standard cotton fabric (SCF) was enhanced by modifying its surface charge, from negative to positive, using Bovine Serum Albumin (BSA) as a cationic agent, to convert it into cationised cotton fabric (CCF). Then, both types of fabrics were dip coated with a simple dip and dry technique for the adsorption of negatively charged graphene oxide (GO) sheets onto its surface. This resulted in 67.74% higher loading amount of GO on the CCF making self-assembly. Finally, this coating was chemically converted by vapor reduction using hydrazine hydrate to reduced graphene oxide (rGO) for restoration of a high electrical conductivity at the fabric surface. Our results revealed that with such high loading of GO, the surface resistance of CCF was only 40Ω/sq as compared to 510Ω/sq of the SCF and a 66% higher photo catalytic activity was also achieved through cationization for improved GO coating. Graphene coated SCF and CCF were characterized using FE-SEM, FTIR, Raman, UV-vis, WAXD, EDX and XPS spectroscopy to ascertain successful reduction of GO to rGO. The effect of BSA treatment on adsorption of cotton fabric was studied using drop shape analyzer to measure contact angle and for thermal and mechanical resistance, the fabric was tested for TGA and tensile strength, respectively. rGO coated fabric also showed slightly improved thermal stability yet a minor loss of strength was observed. The high flexibility, photocatalytic activity and excellent conductivity of this fabric suggests that it can be used as an electrode material for various applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detecting Corrosion Resistance of Coated Steel Rebars by Electrochemical Technique (eis)

NASA Astrophysics Data System (ADS)

Ryou, J.; Shah, S.

Electrochemical impedance spectroscopy (EIS) is one of the electrochemical techniques used in materials science. The present measurements are used to evaluate the corrosion resistance of new types of coated steel rebar used in reinforced concrete. In this study, Si-based coating materials are used and evaluated, because adding Si to metals and alloys, including steel, generally increases their corrosion, oxidation, and erosion resistance. The result suggests that electrochemical impedance spectroscopy may be useful for monitoring corrosion activity on coated steel rebars. Based upon impedance changes, it appears that the silicon powder coating bonds well to the steel, and that the coating has a good performance.

Transfer of Wire Arc-Sprayed Metal Coatings onto Plastic Parts

NASA Astrophysics Data System (ADS)

Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Hopmann, Ch.; Ochotta, P.

2018-01-01

By means of In-Mold-Metal-Spraying (IMMS), metal coatings deposited by means of arc spraying process (ASP) can be transferred onto plastic parts during injection molding, thus realizing an efficient production of metallized plastic parts. Parts produced by means of IMMS can be used in electrical applications. In the current study, the electrical resistivity of coatings applied with different feedstock materials was determined. As a starting point, pressurized air is used as atomizing gas for ASP. In contrast to Zn coatings, Cu coatings applied with pressurized air exhibit a significantly higher electrical resistivity in comparison with massive material. One possible reason is the more pronounced oxidation of Cu particles during ASP. Therefore, N2 and a mixture of N2 and H2 were used as atomizing gas. As a result, the electrical resistivity of coatings applied by means of IMMS could be significantly reduced. Furthermore, standoff distance, current and pressure of the atomizing gas were varied to investigate the influence of these process parameters on the electrical resistivity of Zn coatings using a full factorial experiment design with center point. It can be observed that the electrical resistivity of the Zn coatings increases with decreasing current and increasing standoff distance and pressure.

Transfer of Wire Arc-Sprayed Metal Coatings onto Plastic Parts

NASA Astrophysics Data System (ADS)

Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Hopmann, Ch.; Ochotta, P.

2017-12-01

By means of In-Mold-Metal-Spraying (IMMS), metal coatings deposited by means of arc spraying process (ASP) can be transferred onto plastic parts during injection molding, thus realizing an efficient production of metallized plastic parts. Parts produced by means of IMMS can be used in electrical applications. In the current study, the electrical resistivity of coatings applied with different feedstock materials was determined. As a starting point, pressurized air is used as atomizing gas for ASP. In contrast to Zn coatings, Cu coatings applied with pressurized air exhibit a significantly higher electrical resistivity in comparison with massive material. One possible reason is the more pronounced oxidation of Cu particles during ASP. Therefore, N2 and a mixture of N2 and H2 were used as atomizing gas. As a result, the electrical resistivity of coatings applied by means of IMMS could be significantly reduced. Furthermore, standoff distance, current and pressure of the atomizing gas were varied to investigate the influence of these process parameters on the electrical resistivity of Zn coatings using a full factorial experiment design with center point. It can be observed that the electrical resistivity of the Zn coatings increases with decreasing current and increasing standoff distance and pressure.

Microstructure and Wear Resistance of Composite Coating by Laser Cladding Al/TiN on the Ti-6Al-4V Substrate

NASA Astrophysics Data System (ADS)

Zhang, H. X.; Yu, H. J.; Chen, C. Z.

2015-05-01

The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti-6Al-4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the coating and the substrate. The composite coatings were mainly composed of the matrix of β-Ti (Al) and the reinforcements of titanium nitride (TiN), Ti3Al, TiAl and Al3Ti. The hardness and wear resistance of the coatings on four samples were greatly improved, among which sample 4 exhibited the highest hardness and best wear resistance. The hardness of the coating on sample 4 was approximately 2.5 times of the Ti-6Al-4V substrate. And the wear resistance of sample 4 was four times of the substrate.

Low Volatile Organic Compound (VOC) Chemical Agent Resistant Coating (CARC)

DTIC Science & Technology

2000-04-01

hv1p 30 0 4 7 120 40 B15 +++--·····-+ 46168 36521 28 75 5 hv1p 30 0 2 3 75 80 Bl6 ++++++++++++ 46168 36521 28 120 30 conv 240 I 4 7 120 80 Low...Conventional· Bl2 28 HVLP Bl3 7 Conventional 1.4 1.2 2 Bl4 7 HVLP 1.1 2.3 4 BlS 28 HVLP B16 28 Conventional Notes: I. Only panel sets coated with...p p Bl4 572 574 3.0 4.0 4.0 3.5 p p BIS 274 243 4.0 4.0 4.0 4.5 p p Bl6 360 334 4.0 4.0 4.0 4.0 p p Experimental Set WR 7 days /lSO"C Oil

Microstructure and properties of Cu-Sn-Zn-TiO 2 nano-composite coatings on mild steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Weidong; Cao, Di; Jin, Yunxue

Cu-Sn-Zn coatings have been widely used in industry for their unique properties, such as good conductivity, high corrosion resistance and excellent solderability. To further improve the mechanical performance of Cu-Sn-Zn coatings, powder-enhanced method was applied and Cu-Sn-Zn-TiO 2 nano-composite coatings with different TiO 2 concentration were fabricated. The microstructure of Cu-Sn-Zn-TiO 2 nano-composite coatings were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The mechanical properties of coatings including microhardness and wear resistance were studied. The results indicate that the incorporation of TiO 2 nanoparticle can significantly influence the properties of Cu-Sn-Zn coatings. The microhardness of Cu-Sn-Zn coatingmore » was increased to 383 HV from 330 HV with 1 g/L TiO 2 addition. Also, the corrosion resistance of coating was enhanced. The effects of TiO 2 nanoparticle concentration on the microstructure, mechanical properties and corrosion resistance of Cu-Sn-Zn-TiO 2 nano-composite coatings were discussed.« less

Microstructure and properties of Cu-Sn-Zn-TiO 2 nano-composite coatings on mild steel

DOE PAGES

Gao, Weidong; Cao, Di; Jin, Yunxue; ...

2018-04-18

Cu-Sn-Zn coatings have been widely used in industry for their unique properties, such as good conductivity, high corrosion resistance and excellent solderability. To further improve the mechanical performance of Cu-Sn-Zn coatings, powder-enhanced method was applied and Cu-Sn-Zn-TiO 2 nano-composite coatings with different TiO 2 concentration were fabricated. The microstructure of Cu-Sn-Zn-TiO 2 nano-composite coatings were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The mechanical properties of coatings including microhardness and wear resistance were studied. The results indicate that the incorporation of TiO 2 nanoparticle can significantly influence the properties of Cu-Sn-Zn coatings. The microhardness of Cu-Sn-Zn coatingmore » was increased to 383 HV from 330 HV with 1 g/L TiO 2 addition. Also, the corrosion resistance of coating was enhanced. The effects of TiO 2 nanoparticle concentration on the microstructure, mechanical properties and corrosion resistance of Cu-Sn-Zn-TiO 2 nano-composite coatings were discussed.« less

Study on ceramic coating on the enamel surface using a carbon dioxide laser.

PubMed

Nihei, Tomotaro; Kurata, Shigeaki; Ohashi, Katsura; Umemoto, Kozo; Teranaka, Toshio

2011-01-01

The aims of this study were to evaluate a new restorative method using a carbon dioxide laser (CO(2)-laser) and to evaluate the acid resistance of teeth. Experimental calcium phosphate glass (CPG) powder and two low melting point ceramics (Finesse and zirconium silicate) were fused to enamel surfaces using a CO(2)-laser at an irradiation intensity of 1.0 watt for 30 seconds with a beam size of 0.49 mm at the focal point. The treated teeth were observed with a scanning electron microscope, and the acid resistance of the treated enamel surfaces was evaluated. The CPG fused successfully to the enamel surface, and the treated enamel surface showed high acid resistance compared with the low melting point ceramics and the non-irradiated surfaces. This system may lead to the development of new restorative methods that do not require the use of bonding agents.

Development of improved high temperature coatings for IN-792 + HF

NASA Technical Reports Server (NTRS)

Profant, D. D.; Naik, S. K.

1981-01-01

The development for t-55 l712 engine of high temperature for integral turbine nozzles with improved thermal fatigue resistance without sacrificing oxidation/corrosion protection is discussed. The program evaluated to coating systems which comprised one baseline plasma spray coating (12% Al-NiCoCrALY), three aluminide coatings including the baseline aluminide (701), two CoNiCrAly (6% Al) + aluminide systems and four NiCoCrY + aluminide coating were evaluated. The two-step coating processes were investigated since it offered the advantage of tailoring the composition as well as properly coating surfaces of an integral or segmented nozzle. Cyclic burner rig thermal fatigue and oxidation/corrosion tests were used to evaluate the candidate coating systems. The plasma sprayed 12% Al-NiCoCrAlY was rated the best coating in thermal fatigue resistance and outperformed all coatings by a factor between 1.4 to 2.5 in cycles to crack initiation. However, this coatings is not applicable to integral or segmented nozzles due to the line of sight limitation of the plasma spray process. The 6% Al-CoNiCrAlY + Mod. 701 aluminide (32 w/o Al) was rated the best coating in oxidation/corrosion resistance and was rated the second best in thermal fatigue resistance.

Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline

PubMed Central

Ammar, Ameen Uddin; Shahid, Muhammad; Ahmed, Muhammad Khitab; Khan, Munawar; Khalid, Amir

2018-01-01

Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using the “three electrode system”. Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene) and TiO2/GO (graphene oxide) nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and “produce water” of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples. PMID:29495339

Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline.

PubMed

Ammar, Ameen Uddin; Shahid, Muhammad; Ahmed, Muhammad Khitab; Khan, Munawar; Khalid, Amir; Khan, Zulfiqar Ahmad

2018-02-25

Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using the "three electrode system". Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene) and TiO₂/GO (graphene oxide) nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and "produce water" of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples.

Surface acoustic wave oxygen sensor

NASA Technical Reports Server (NTRS)

Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

1994-01-01

A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

Method of making nanopatterns and nanostructures and nanopatterned functional oxide materials

DOEpatents

Dravid, Vinayak P; Donthu, Suresh K; Pan, Zixiao

2014-02-11

Method for nanopatterning of inorganic materials, such as ceramic (e.g. metal oxide) materials, and organic materials, such as polymer materials, on a variety of substrates to form nanopatterns and/or nanostructures with control of dimensions and location, all without the need for etching the materials and without the need for re-alignment between multiple patterning steps in forming nanostructures, such as heterostructures comprising multiple materials. The method involves patterning a resist-coated substrate using electron beam lithography, removing a portion of the resist to provide a patterned resist-coated substrate, and spin coating the patterned resist-coated substrate with a liquid precursor, such as a sol precursor, of the inorganic or organic material. The remaining resist is removed and the spin coated substrate is heated at an elevated temperature to crystallize the deposited precursor material.

Strength and wear resistance of a dental glass-ionomer cement with a novel nanofilled resin coating.

PubMed

Lohbauer, Ulrich; Krämer, Norbert; Siedschlag, Gustavo; Schubert, Edward W; Lauerer, Brigitte; Müller, Frank A; Petschelt, Anselm; Ebert, Johannes

2011-04-01

To evaluate the influence of different resin coating protocols on the fracture strength and wear resistance of a commercial glass-ionomer cement (GIC). A new restorative concept [Equia (GC Europe)] has been introduced as a system application consisting of a condensable GIC (Fuji IX GP Extra) and a novel nanofilled resin coating material (G-Coat Plus). Four-point fracture strength (FS, 2 x 2 x 25 mm, 14-day storage, distilled water, 37 degrees C) were produced and measured from three experimental protocols: no coating GIC (Group 1), GIC coating before water contamination (Group 2), GIC coating after water contamination (Group 3). The strength data were analyzed using Weibull statistics. Three-body wear resistance (Group 1 vs. Group 2) was measured after each 10,000 wear cycles up to a total of 200,000 cycles using the ACTA method. GIC microstructure and interfaces between GIC and coating materials were investigated under SEM and CLSM. The highest FS of 26.1 MPa and the most homogenous behavior (m = 7.7) has been observed in Group 2. The coated and uncoated GIC showed similar wear resistance until 90,000 cycles. After 200,000 wear cycles, the coated version showed significantly higher wear rate (ANOVA, P< 0.05). The coating protocol has been shown to determine the GIC fracture strength. Coating after water contamination and air drying is leading to surface crack formation thus significantly reducing the FS. The resin coating showed a proper sealing of GIC surface porosities and cracks. In terms of wear, the coating did not improve the wear resistance of the underlying cement as similar or higher wear rates have been measured for Group 1 versus Group 2.

Hybrid magnetite nanoparticles/ Rosmarinus officinalis essential oil nanobiosystem with antibiofilm activity

NASA Astrophysics Data System (ADS)

Chifiriuc, Carmen; Grumezescu, Valentina; Grumezescu, Alexandru Mihai; Saviuc, Crina; Lazăr, Veronica; Andronescu, Ecaterina

2012-04-01

Biofilms formed by fungal organisms are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence of the fungi despite antifungal therapy. The purpose of this study is to combine the unique properties of nanoparticles with the antimicrobial activity of the Rosmarinus officinalis essential oil in order to obtain a nanobiosystem that could be pelliculised on the surface of catheter pieces, in order to obtain an improved resistance to microbial colonization and biofilm development by Candida albicans and C. tropicalis clinical strains. The R. officinalis essential oils were extracted in a Neo-Clevenger type apparatus, and its chemical composition was settled by GC-MS analysis. Functionalized magnetite nanoparticles of up to 20 nm size had been synthesized by precipitation method adapted for microwave conditions, with oleic acid as surfactant. The catheter pieces were coated with suspended core/shell nanoparticles (Fe3O4/oleic acid:CHCl3), by applying a magnetic field on nanofluid, while the CHCl3 diluted essential oil was applied by adsorption in a secondary covering treatment. The fungal adherence ability was investigated in six multiwell plates, in which there have been placed catheters pieces with and without hybrid nanoparticles/essential oil nanobiosystem pellicle, by using culture-based methods and confocal laser scanning microscopy (CLSM). The R. officinalis essential oil coated nanoparticles strongly inhibited the adherence ability and biofilm development of the C. albicans and C. tropicalis tested strains to the catheter surface, as shown by viable cell counts and CLSM examination. Due to the important implications of C andida spp. in human pathogenesis, especially in prosthetic devices related infections and the emergence of antifungal tolerance/resistance, using the new core/shell/coated shell based on essential oil of R. officinalis to inhibit the fungal adherence could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with antibiofilm properties.

The effect of multiple antireflective coatings and center thickness on resistance of polycarbonate spectacle lenses to penetration by pointed missiles.

PubMed

Chou, B Ralph; Gupta, Alina; Hovis, Jeffery K

2005-11-01

Previous work has shown that the impact resistance to blunt missiles is affected by coatings applied to either CR-39 or polycarbonate lenses. We investigated the effects of multiple antireflection (minimum angle of resolution [MAR]) coatings on the resistance of polycarbonate lenses to puncture on impact by sharp, high-speed missiles. Four groups of surfaced plano polycarbonate lenses were investigated. Two groups had a scratch-resistant (SR) coating applied to both surfaces. One of these groups had a 2-mm center thickness and the other had a 3-mm center thickness. The other two groups of 2-mm and 3-mm thick lenses had a MAR coating applied over the SR coating. The lenses were impacted by a missile consisting of an industrial sewing machine needle mounted in a cylindrical aluminum carrier. The sharp missiles were able to pierce the lenses at speeds between 29.6 m/s and 46.2 m/s. Impact resistance was lowest for the thinner lenses and lenses with a MAR coating. The effect of the MAR and lens thickness was subadditive. We have confirmed previous observations that polycarbonate lenses are more susceptible to penetration by sharp, high-speed missiles than blunt missiles. We have also found that reducing lens center thickness and applying a MAR coating further reduces the penetration resistance. Therefore, the use of 2-mm center thickness and MAR-coated polycarbonate lenses should be discouraged for industrial eye protectors where sharp missile hazards are possible.

Ultrasonic irradiation and its application for improving the corrosion resistance of phosphate coatings on aluminum alloys.

PubMed

Sheng, Minqi; Wang, Chao; Zhong, Qingdong; Wei, Yinyin; Wang, Yi

2010-01-01

In this paper, ultrasonic irradiation was utilized for improving the corrosion resistance of phosphate coatings on aluminum alloys. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The effect of ultrasonic irradiation on the corrosion resistance of phosphate coatings was investigated by polarization curves and electrochemical impedance spectroscopy (EIS). Various effects of the addition of Nd(2)O(3) in phosphating bath on the performance of the coatings were also investigated. Results show that the composition of phosphate coating were Zn(3)(PO(4))(2).4H(2)O(hopeite) and Zn crystals. The phosphate coatings became denser with fewer microscopic holes by utilizing ultrasonic irradiation treatment. The addition of Nd(2)O(3) reduced the crystallinity of the coatings, with the additional result that the crystallites were increasingly nubby and spherical. The corrosion resistance of the coatings was also significantly improved by ultrasonic irradiation treatment; both the anodic and cathodic processes of corrosion taking place on the aluminum alloy substrate were suppressed consequently. In addition, the electrochemical impedance of the coatings was also increased by utilizing ultrasonic irradiation treatment compared with traditional treatment.

Electropolymerization of camphorsulfonic acid doped conductive polypyrrole anti-corrosive coating for 304SS bipolar plates

NASA Astrophysics Data System (ADS)

Jiang, Li; Syed, Junaid Ali; Gao, Yangzhi; Zhang, Qiuxiang; Zhao, Junfeng; Lu, Hongbin; Meng, Xiangkang

2017-12-01

Conductive polymer coating doped with large molecular organic acid is an alternative method used to protect stainless steel (SS) bipolar plates in proton exchange membrane fuel cells (PEMFCs). However, it is difficult to select the proper doping acid, which improves the corrosion resistance of the coating without affecting its conductivity. In this study, large spatial molecular group camphorsulfonic acid (CSA) doped polypyrrole (PPY) conductive coating was prepared by galvanostatic electropolymerization on 304SS. The electrochemical properties of the coating were evaluated in 0.1 M H2SO4 solution in order to simulate the PEMFC service environment. The results indicate that the coating increased the corrosion potential and shifted Ecorr towards more positive value, particularly the jcorr value of PPY-CSA coated 304SS was dropped from 97.3 to 0.00187 μA cm-2. The long-term immersion tests (660 h) show that the PPY-CSA coating exhibits better corrosion resistance in comparison with the small acid (SO42-) doped PPY-SO42- or PPY/PPY-SO42- coatings. Moreover, the PPY-CSA coating presents low contact resistance and maintains strong corrosion resistance during the prolonged exposure time due to barrier effect and anodic protection.

Coated metal sintering carriers for fuel cell electrodes

DOEpatents

Donelson, R.; Bryson, E.S.

1998-11-10

A carrier is described for conveying components of a fuel cell to be sintered through a sintering furnace. The carrier comprises a metal sheet coated with a water-based carbon paint, the water-based carbon paint comprising water, powdered graphite, an organic binder, a wetting agent, a dispersing agent and a defoaming agent.

Microstructural, mechanical and oxidation features of NiCoCrAlY coating produced by plasma activated EB-PVD

NASA Astrophysics Data System (ADS)

He, Jian; Guo, Hongbo; Peng, Hui; Gong, Shengkai

2013-06-01

NiCoCrAlY coatings produced by electron beam-physical vapor deposition (EB-PVD) have been extensively used as the oxidation resistance coatings or suitable bond coats in thermal barrier coating (TBC) system. However, the inherent imperfections caused by EB-PVD process degrade the oxidation resistance of the coatings. In the present work, NiCoCrAlY coatings were creatively produced by plasma activated electron beam-physical vapor deposition (PA EB-PVD). The novel coatings showed a terraced substructure on the surface of each grain due to the increased energy of metal ions and enhanced mobility of adatoms. Also a strong (1 1 1) crystallographic texture of γ/γ' grains was observed. The toughness of the coatings got remarkably improved compared with the coatings deposited by conventional EB-PVD and the oxidation behavior at 1373 K showed that the novel coatings had excellent oxidation resistance. The possible mechanism was finally discussed.

A Comparative Study of the Microstructure, Mechanical Properties and Corrosion Resistance of Ni- or Fe- Based Composite Coatings by Laser Cladding

NASA Astrophysics Data System (ADS)

Wan, M. Q.; Shi, J.; Lei, L.; Cui, Z. Y.; Wang, H. L.; Wang, X.

2018-04-01

Ni- and Fe-based composite coatings were laser cladded on 40Cr steel to improve the surface mechanical property and corrosion resistance, respectively. The microstructure and phase composition were analyzed by x-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) equipped with an energy-dispersive spectrometer (EDS). The micro-hardness, tribological properties and electrochemical corrosion behavior of the coatings were evaluated. The results show that the thickness of both the coatings is around 0.7 mm, the Ni-based coating is mainly composed of γ-(Ni, Fe), FeNi3, Ni31Si12, Ni3B, CrB and Cr7C3, and the Fe-based coating is mainly composed of austenite and (Fe, Cr)7C3. Micro-hardness of the Ni-based composite coating is about 960 HV0.3, much higher than that of Fe-based coating (357.4 HV0.3) and the 40Cr substrate (251 HV0.3). Meanwhile, the Ni-based composite coating possesses better wear resistance than the Fe-based coating validated by the worn appearance and the wear loss. Electrochemical results suggested that Ni-based coating exhibited better corrosion resistance than the Fe-based coating. The 40Cr substrate could be well protected by the Ni-based coating.

Hot Corrosion Resistance and Mechanical Behavior of Atmospheric Plasma Sprayed Conventional and Nanostructured Zirconia Coatings

NASA Astrophysics Data System (ADS)

Saremi, Mohsen; Keyvani, Ahmad; Heydarzadeh Sohi, Mahmoud

Conventional and nanostructured zirconia coatings were deposited on In-738 Ni super alloy by atmospheric plasma spray technique. The hot corrosion resistance of the coatings was measured at 1050°C using an atmospheric electrical furnace and a fused mixture of vanadium pent oxide and sodium sulfate respectively. According to the experimental results nanostructured coatings showed a better hot corrosion resistance than conventional ones. The improved hot corrosion resistance could be explained by the change of structure to a dense and more packed structure in the nanocoating. The evaluation of mechanical properties by nano indentation method showed the hardness (H) and elastic modulus (E) of the YSZ coating increased substantially after hot corrosion.

On the influence of Ti-Al intermetallic coating architecture on mechanical properties and wear resistance of end mills

NASA Astrophysics Data System (ADS)

Vardanyan, E. L.; Budilov, V. V.; Ramazanov, K. N.; Ataullin, Z. R.

2017-07-01

Thin-film wear-resistant coatings are widely used to increase life and efficiency of metal cutting tools. This paper shows the results of a study on the influence of architecture (number, sequence and thickness of layers) of wear-resistant coatings on physical, mechanical and operational properties of end mills. Coatings consisting of alternating Ti-Al/Ti-Al-N layers of equal thickness demonstrated the best physical and mechanical properties. Durability of coated tools when processing materials from chromium-vanadium steel increased twice as compared to uncoated tools.

Erythrocyte membrane-coated NIR-triggered biomimetic nanovectors with programmed delivery for photodynamic therapy of cancer.

PubMed

Ding, Hui; Lv, Yanlin; Ni, Dezhi; Wang, Jie; Tian, Zhiyuan; Wei, Wei; Ma, Guanghui

2015-06-07

A new type of photodynamic therapy (PDT) agents using upconversion nanoparticles (UCNPs) with incorporated photosensitizers as the inner core and an erythrocyte membrane (RM) decorated with dual targeting moieties as the cloak is developed. Owing to the endogenous nature of RM, the RM-coating endows the PDT agents with perfect biocompatibility and stealth ability to escape from the entrapment by the reticulo-endothelial system (RES). More importantly, owing to the unique nature of erythrocyte as an oxygen carrier in the blood, the RM outer layer of the agents unequivocally facilitates the permeation of ground-state molecular oxygen ((3)O2) and the singlet oxygen ((1)O2) as compared to the previously developed PDT agents with other types of coating. Another salient feature of the as-prepared PDT platform is the decoration of RM with dual targeting moieties for selective recognition of cancer cells and mitochondrial targeting, respectively. The synergistic effect of RM coating and dual-targeting of such feature-packed agents are investigated in tumor-bearing mice and the improved PDT therapeutic efficacy is confirmed, which is the first paradigm where RM-coated NIR-triggered nanovectors with programmed delivery ability is applied in PDT of tumor in vivo.

Effects of nanoscale coatings on reliability of MEMS ohmic contact switches

NASA Astrophysics Data System (ADS)

Tremper, Amber Leigh

This thesis examines how the electrical and mechanical behavior of Au thin films is altered by the presence of ultra-thin metallic coatings. To examine the mechanical behavior, nanoindentation, nano-scratch, and atomic force microscopy (AFM) testing was performed. The electrical behavior was evaluated through Kelvin probe contact resistance measurements. This thesis shows that ultra-thin, hard, ductile coatings on a softer, ductile underlying layer (such as Ru or Pt on Au) had a significant effect on mechanical behavior of the system, and can be tailored to control the deformation resistance of the thin film system. Despite Ru and Pt having a higher hardness and plane strain modulus than Au, the Ru and Pt coatings decreased both the hardness and plane strain modulus of the layered system when the indentation depth was on the order of the coating thickness. Alternately, when the indentation depth was several times the coating thickness, the ductile, plastically hard, elastically stiff layer significantly hardened the contact response. These results correlate well with membrane stress theoretical predictions, and demonstrate that membrane theory can be applied even when the ratio of indentation depth, h, to coating thickness, t, is very large ( h/t<10). The transition from film-substrate models to membrane models occurs when the indent penetration depth to coating thickness ratio is less than ˜0.5. When the electrical behavior of the Ru-coated Au films was examined, it was found that all the measured resistances of the Au-only film and Ru-coated systems were several orders of magnitude larger than those predicted by Holm's law, but were still in good agreement with previously reported values in the literature. Previous studies attributed the high contact resistances to a variety of causes, including the buildup of an insulating contamination layer. This thesis determined the cause of the deviations to be large sheet resistance contributions to the total measured resistance. Further, studies on aged samples (with thicker contamination layers) conclusively showed that, while contamination increases the contact resistance, it also increases the dependence on force. This thesis also details that the relative contribution of contact resistance to the total measured resistance can be maximized by decreasing the probe spacing and tip radius. AFM testing of the layered systems showed that the coated samples had larger predicted plane strain moduli than the Au sample, in contrast to the nanoindentation testing. Thus, when the contact depth was kept sufficiently small, the contact stiffness increased as predicted by substrate models. When the contact depth was on the order of the coating thickness, the contact stiffness actually decreased. Additionally, the forceseparation plots showed that the Ru and Pt surfaces either accumulated large amounts of contamination or were less susceptible to being wiped clean than the Au film. Further, scratch testing of the Au film and Ru and Pt coatings show that the hard surface coatings reduce material removal and contact wear. Ultra-thin Ru and Pt surface coatings on Au films are shown to be improved material systems for ohmic contact switches. The wear is reduced for coated materials, while the resistance and power consumption through the coating are not significantly affected.

Development and Characterization of Nanostructured Cermet Coatings Produced by Co-electrodeposition

NASA Astrophysics Data System (ADS)

Farrokhzad, Mohammad Ali

Nanostructured cermet (ceramic-metallic) coatings are a group of materials that combine properties possessed by ceramics, such as oxidation resistance and high hardness, and the properties of metals such as strength and ductility. These coatings consist of nano-sized metal-oxide particles (i.e. Al2 O3) dispersed into a corrosion resistant metal matrix such as nickel. Cermet coatings have been used in many industrial applications such as cutting tools and jet engines where high temperature and erosion resistance performance are required. However, despite the promising properties, the lack of experimental data and theories on high temperature oxidation and mechanical properties of cermet coatings have restricted their full potential to be used in technologies for oil sand production such as In-Situ Combustion (ISC). In this study, the structure of cermet coatings was investigated to identify the characteristics that give rise to oxidation performance and wear resistance properties of cermet coatings. The experimental oxidation results on the single-component oxide cermet coatings showed that when Al2O3 and TiO2 were combined in the electrolyte, the new combination can improve oxidation performance (less mass gain) as compared to a pure Ni coating. Based on the oxidation and micro-hardness results, a new group of nanostructured cermet coatings (double-component oxides) was developed and investigated using long term oxidation tests, thermo-gravimetric analysis in mixed gas, thermal cycling, micro-hardness and abrasive wear tests. The mechanical analysis of the newly developed coatings showed improved resistance against wear and thermal cycling compared to single-component oxide cermet and pure Ni coatings. Furthermore, some new theoretical analysis were also put forward that aims at a new explanation of high temperature oxidation for cermet coatings.

Combined slurry and cavitation erosion resistance of surface modified SS410 stainless steel

NASA Astrophysics Data System (ADS)

Amarendra, H. J.; Pratap, M. S.; Karthik, S.; Punitha Kumara, M. S.; Rajath, H. C.; Ranjith, H.; Shubhatunga, S. V.

2018-03-01

Slurry erosion and combined slurry and cavitation erosion resistance of thermal spray coatings are studied and compared with the as-received martensitic stainless steel material. 70Ni-Cr coatings are deposited on SS 410 material through plasma thermal spray process. The synergy effect of the combined slurry and cavitation erosion resistance of plasma thermal spray coatings were investigated in a slurry pot tester in the presence of bluff bodies known as Cavitation Inducers. Results showed the combined slurry and cavitation erosion resistance of martensitic stainless steel - 410 can be improved by plasma thermal spray coating. It is observed that the plasma spray coated specimens are better erosion resistant than the as- received material, subjected to erosion test under similar conditions. As-received and the surface modified steels are mechanically characterized for its hardness, bending. Morphological studies are conducted through scanning electron microscope.

Biocorrosion resistance of coated magnesium alloy by microarc oxidation in electrolyte containing zirconium and calcium salts

NASA Astrophysics Data System (ADS)

Wang, Ya-Ming; Guo, Jun-Wei; Wu, Yun-Feng; Liu, Yan; Cao, Jian-Yun; Zhou, Yu; Jia, De-Chang

2014-09-01

The key to use magnesium alloys as suitable biodegradable implants is how to adjust their degradation rates. We report a strategy to prepare biocompatible ceramic coating with improved biocorrosion resistance property on AZ91D alloy by microarc oxidation (MAO) in a silicate-K2ZrF6 solution with and without Ca(H2PO4)2 additives. The microstructure and biocorrosion of coatings were characterized by XRD and SEM, as well as electrochemical and immersion tests in simulated body fluid (SBF). The results show that the coatings are mainly composed of MgO, Mg2SiO4, m-ZrO2 phases, further Ca containing compounds involve the coating by Ca(H2PO4)2 addition in the silicate-K2ZrF6 solution. The corrosion resistance of coated AZ91D alloy is significantly improved compared with the bare one. After immersing in SBF for 28 d, the Si-Zr5-Ca0 coating indicates a best corrosion resistance performance.

Abrasion-Resistant Coating for Flexible Insulation

NASA Technical Reports Server (NTRS)

Mui, D.; Headding, R. E.

1986-01-01

Ceramic coating increases durability and heat resistance of flexible high-temperature insulation. Coating compatible with quartz-fabric insulation allowing it to remain flexible during and after repeated exposures to temperatures of 1,800 degree F (982 degree C). Prevents fabric from becoming brittle while increasing resistance to aerodynamic abrasion and loading. Coating consists of penetrating precoat and topcoat. Major ingredients high-purity colloidal silica binder and ground silica filler, which ensure stability and compatibility with fabric at high temperatures. Both precoat and topcoat cured at room temperature.

Development of a Long-Life-Cycle, Highly Water-Resistant Solar Reflective Retrofit Roof Coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polyzos, Georgios; Hunter, Scott; Sharma, Jaswinder

2016-03-04

Highly water-resistant and solar-reflective coatings for low-slope roofs are potentially among the most economical retrofit approaches to thermal management of the building envelope. Therefore, they represent a key building technology research program within the Department of Energy. Research efforts in industry and the Department of Energy are currently under way to increase long-term solar reflectance on a number of fronts. These include new polymer coatings technologies to provide longer-lasting solar reflectivity and improved test methodologies to predict long-term soiling and microbial performance. The focus on long-term improvements in soiling and microbial resistance for maximum reflectance does not address the singlemore » most important factor impacting the long-term sustainability of low-slope roof coatings: excellent water resistance. The hydrophobic character of asphaltic roof products makes them uniquely suitable for water resistance, but their low albedo and poor exterior durability are disadvantages. A reflective coating that maintains very high water resistance with increased long-term resistance to soiling and microbial activity would provide additional energy savings and extend roof service life.« less

Preparation and corrosion resistance of magnesium phytic acid/hydroxyapatite composite coatings on biodegradable AZ31 magnesium alloy.

PubMed

Zhang, Min; Cai, Shu; Zhang, Feiyang; Xu, Guohua; Wang, Fengwu; Yu, Nian; Wu, Xiaodong

2017-06-01

In this work, a magnesium phytic acid/hydroxyapatite composite coating was successfully prepared on AZ31 magnesium alloy substrate by chemical conversion deposition technology with the aim of improving its corrosion resistance and bioactivity. The influence of hydroxyapatite (HA) content on the microstructure and corrosion resistance of the coatings was investigated. The results showed that with the increase of HA content in phytic acid solution, the cracks on the surface of the coatings gradually reduced, which subsequently improved the corrosion resistance of these coated magnesium alloy. Electrochemical measurements in simulated body fluid (SBF) revealed that the composite coating with 45 wt.% HA addition exhibited superior surface integrity and significantly improved corrosion resistance compared with the single phytic acid conversion coating. The results of the immersion test in SBF showed that the composite coating could provide more effective protection for magnesium alloy substrate than that of the single phytic acid coating and showed good bioactivity. Magnesium phytic acid/hydroxyapatite composite, with the desired bioactivity, can be synthesized through chemical conversion deposition technology as protective coatings for surface modification of the biodegradable magnesium alloy implants. The design idea of the new type of biomaterial is belong to the concept of "third generation biomaterial". Corrosion behavior and bioactivity of coated magnesium alloy are the key issues during implantation. In this study, preparation and corrosion behavior of magnesium phytic acid/hydroxyapatite composite coatings on magnesium alloy were studied. The basic findings and significance of this paper are as follows: 1. A novel environmentally friendly, homogenous and crack-free magnesium phytic acid/hydroxyapatite composite coating was fabricated on AZ31 magnesium alloy via chemical conversion deposition technology with the aim of enhancing its corrosion resistance and bioactivity. The chemical conversion coatings, which are formed through the reaction between the substrate and the environment, have attracted increasing attention owing to the relative low treatment temperature, favorable bonding to substrate and simple implementation process. 2. With the increasing of hydroxyapatite (HA) content, the crack width in the composite coatings and the thickness of the coatings exhibit obviously decreased. The reason is probably that when adding HA into the phytic acid solution, the amount of active hydroxyl groups in the phytic acid are reduced via forming the coordination bond between P-OH groups from phytic acid and P-OH groups from the surface of HA, thus decreasing the coating thickness and hydrogen formation, as well as avoiding coating cracking. 3. By adjusting the HA content to 45 wt.%, a dense and relatively smooth composite coating with ~1.4 μm thickness is obtained on magnesium alloy, and exhibits high corrosion resistance and good bioactivity when compared with the single phytic acid conversion coating.

White primer permits a corrosion-resistant coating of minimum weight

NASA Technical Reports Server (NTRS)

Albrecht, R. H.; Jensen, D. P.; Schnake, P.

1966-01-01

White primer for coating 2219 aluminum alloy supplies a base for a top coating of enamel. A formulation of pigments and vehicle results in a primer with high corrosion resistance and minimum film thickness.

Hydroxyapatite/poly(epsilon-caprolactone) double coating on magnesium for enhanced corrosion resistance and coating flexibility.

PubMed

Jo, Ji-Hoon; Li, Yuanlong; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag

2013-11-01

Hydroxyapatite was deposited on pure magnesium (Mg) with a flexible poly(ε-caprolactone) interlayer to reduce the corrosion rate of Mg and enhance coating flexibility. The poly(ε-caprolactone) interlayer was uniformly coated on Mg by a spraying method, followed by hydroxyapatite deposition on the poly(ε-caprolactone) using an aerosol deposition method. In scanning electron microscopy observations, inorganic/organic composite-like structure was observed between the hydroxyapatite and poly(ε-caprolactone) layers, resulting from the collisions of hydroxyapatite particles into the poly(ε-caprolactone) matrix at the initial stage of the aerosol deposition. The corrosion resistance of the coated Mg was examined using potentiodynamic polarization tests. The hydroxyapatite/poly(ε-caprolactone) double coating remarkably improved the corrosion resistance of Mg in Hank's solution. In the in vitro cell tests, the coated Mg showed better cell adhesion compared with the bare Mg due to the reduced corrosion rate and enhanced biocompatibility. The stability and flexibility of hydroxyapatite/poly(ε-caprolactone) double coating was investigated by scanning electron microscopy inspections after the coated Mg was deformed. The hydroxyapatite coating on the poly(ε-caprolactone) interlayer revealed enhanced coating stability and flexibility without cracking or delamination during bending and stretching compared with the hydroxyapatite single coating. These results demonstrated that the hydroxyapatite/poly(ε-caprolactone) double coating significantly improved the surface corrosion resistance of Mg and enhanced coating flexibility for use of Mg as a biodegradable implant.

Characterization of Microstructure and Wear Resistance of PEO Coatings Containing Various Microparticles on Ti6Al4V Alloy

NASA Astrophysics Data System (ADS)

Li, Xinyi; Dong, Chaofang; Zhao, Qing; Pang, Yu; Cheng, Fasong; Wang, Shuaixing

2018-02-01

Titania-based composite coatings were prepared by plasma electrolytic oxidation (PEO) treatment of Ti6Al4V alloy in electrolyte with α-Al2O3, Cr2O3 or h-BN microparticles in suspension. The microstructure, composition of PEO composite coatings were analyzed by SEM, EDS and XRD. The wear resistance of composite ceramic coatings was studied by ball-on-disk wear test at ambient temperature and 300 °C. The results showed that the addition of microparticles accelerated the growth rate of PEO coating and changed the microstructure and composition of PEO coating. PEO coating was porous and mainly composed of rutile-TiO2, anatase-TiO2 and Al2TiO5. PEO/α-Al2O3 (Cr2O3 or h-BN) composite coating only had small micropores and appeared some α-Al2O3 (Cr2O3 or h-BN) phase. Besides, the addition of α-Al2O3 (Cr2O3 or h-BN) microparticles greatly improved the wear resistance of PEO coating. At ambient temperature, abrasive wear dominated the wear behavior of PEO coating, but abrasive wear and adhesive peel simultaneously happened at 300 °C. Whether at ambient temperature or 300 °C, PEO composite coating had better wear resistance than PEO coating. Besides, PEO/h-BN composite coating outperformed other composite coatings regardless of the temperature.

Oxidation-Resistant Coating For Bipolar Lead/Acid Battery

NASA Technical Reports Server (NTRS)

Bolstad, James J.

1993-01-01

Cathode side of bipolar substrate coated with nonoxidizable conductive layer. Coating prepared as water slurry of aqueous dispersion of polyethylene copolymer plus such conductive fillers as tin oxide, titanium, tantalum, or tungsten oxide. Applied easily to substrate of polyethylene carbon plastic. As slurry dries, conductive, oxidation-resistant coating forms on positive side of substrate.

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

DOEpatents

Sarin, V.K.

1990-08-21

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications is disclosed. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al[sub x]N[sub y]O[sub z] layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al[sub x]N[sub y]O[sub z] layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

DOEpatents

Sarin, Vinod K.

1990-01-01

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al.sub.x N.sub.y O.sub.z layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al.sub.x N.sub.y O.sub.z layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Environmental protection to 922K (1200 F) for titanium alloys

NASA Technical Reports Server (NTRS)

Groves, M. T.

1973-01-01

Evaluations are presented of potential coating systems for protection of titanium alloys from hot-salt stress-corrosion up to temperatures of 755 K (900 F) and from oxidation embrittlement up to temperature of 922 K (1200 F). Diffusion type coatings containing Si, Al, Cr, Ni or Fe as single coating elements or in various combinations were evaluated for oxidation protection, hot-salt stress-corrosion (HSSC) resistance, effects on tensile properties, fatigue properties, erosion resistance and ballistic impact resistance on an alpha and beta phase titanium alloy (Ti-6Al-2Sn-4Zr-2Mo). All of the coatings investigated demonstrated excellent oxidation protectiveness, but none of the coatings provided protection from hot-salt stress-corrosion. Experimental results indicated that both the aluminide and silicide types of coatings actually decreased the HSSC resistance of the substrate alloy. The types of coatings which have typically been used for oxidation protection of refractory metals and nickel base superalloys are not suitable for titanium alloys because they increase the susceptibility to hot-salt stress-corrosion, and that entirely new coating concepts must be developed for titanium alloy protection in advanced turbine engines.

Friction and fretting wear characteristics of different diamond-like carbon coatings against alumina in water-lubricated fretting conditions.

PubMed

Watabe, Tsukasa; Amanov, Auezhan; Tsuboi, Ryo; Sasaki, Shinya

2013-12-01

Diamond-like carbon (DLC) coatings typically show low friction and high wear resistance. In this study, the friction and fretting wear characteristics of PVD, CVD and CVD-Si DLC coatings were investigated against an alumina (Al2O3) ball under water-lubricated fretting conditions. The objective of this study is to investigate and compare the friction and fretting wear characteristics of those DLC coatings at various fretting frequencies. The test results showed that the PVD DLC coating led to a lower friction coefficient and a higher resistance to fretting wear compared to those of the CVD and CVD-Si DLC coatings. However, the CVD DLC coating showed that the fretting wear resistance decreases with increasing frequency, while no significant difference in fretting wear resistances of the PVD and CVD-Si DLC coatings was observed. Quantitative surface analyses of the specimens were performed using an energy dispersive spectroscopy (EDS), a laser scanning microscope (LSM), a scanning electron microscope (SEM), an atomic force microscope (AFM) and the Raman spectroscopy.

Chrome-free Samarium-based Protective Coatings for Magnesium Alloys

NASA Astrophysics Data System (ADS)

Hou, Legan; Cui, Xiufang; Yang, Yuyun; Lin, Lili; Xiao, Qiang; Jin, Guo

The microstructure of chrome-free samarium-based conversion coating on magnesium alloy was investigated and the corrosion resistance was evaluated as well. The micro-morphology, transverse section, crystal structure and composition of the coating were observed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X- ray photoelectron spectroscopy (XPS), respectively. The corrosion resistance was evaluated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The results reveal that the morphology of samarium conversion coating is of crack-mud structure. Tiny cracks distribute in the compact coating deposited by samarium oxides. XRD, EDS and XPS results characterize that the coating is made of amorphous and trivalent-samarium oxides. The potentiodynamic polarization curve, EIS and OCP indicate that the samarium conversion coating can improve the corrosion resistance of magnesium alloys.

Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

NASA Astrophysics Data System (ADS)

Kumar, R. K.; Kamaraj, M.; Seetharamu, S.; Pramod, T.; Sampathkumaran, P.

2016-08-01

The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

Functional Multi-Nanolayer Coatings of Amorphous Carbon/Tungsten Carbide with Exceptional Mechanical Durability and Corrosion Resistance.

PubMed

Nemati, Narguess; Bozorg, Mansoor; Penkov, Oleksiy V; Shin, Dong-Gap; Sadighzadeh, Asghar; Kim, Dae-Eun

2017-09-06

A novel functional multilayer coating with periodically stacked nanolayers of amorphous carbon (a:C)/tungsten carbide (WC) and an adhesion layer of chromium (Cr) was deposited on 304 stainless steel using a dual magnetron sputtering technique. Through process optimization, highly densified coatings with high elasticity and shear modulus, excellent wear resistance, and minimal susceptibility to corrosive and caustic media could be acquired. The structural and mechanical properties of the optimized coatings were studied in detail using a variety of analytical techniques. Furthermore, finite element method simulations indicated that the stress generated due to contact against a steel ball was distributed well within the coating, which allowed the stresses to be lower than the yield threshold of the coating. Thus, an ultralow wear rate of ∼10 -12 mm 3 /N mm could be achieved in dry sliding conditions under relatively high Hertzian contact pressures of ∼0.4-0.9 GPa. The amorphous and pinhole-free structure of the individual layers, sufficient number of pairs, and the relatively dense stacked layers resulted in significant polarization resistance (Z″ = 5.5 × 10 6 Ω cm 2 ) and increased the corrosion resistance of the coating by 10-fold compared to that of recently reported corrosion-resistant coatings.

A study on porous super austenitic stainless steel coating for improvement of bone ingrowth

NASA Astrophysics Data System (ADS)

Oh, Keun Taek; Park, Yong Soo

1998-02-01

In this study, the prostheses were provided with the bone ingrowth site by coating the super stainless steel powder on the same substrate (S32050) using plasma spraying method. Plasma current and powder feed rate varied in this study based on the optimum conditions of previous experiments. The optimum conditions for satisfying the requirements of the porous coatings were found. The characteristics of the coatings were observed according to the experimental parameters. It was found that plasma current influenced the chemical composition (the oxides, Cr component), melting and flattening degree of the sprayed particle (surface roughness, thickness of the splat, pores) and corrosion -resistance. The powder feed rate also influenced the coating thickness and efficiency. The amount of Cr was increased, but Ni, Mo, Fe were decreased with plasma current. An increase of Cr in the coating surface corresponded to an increase in the amount of the formed oxides. The coated specimen in 400A had a high corrosion-resistance owing to a dense coating. The coated specimen in 500A formed many types of oxides. In 300A current, the coating was rough with many pores, and corrosion-resistance of the coating showed a large variation according to the oxidation and compositional change. Specifically at 100 g/min powder feed rate in a 300A current, the coating was rough and porous, nevertheless, it had high corrosion resistance.

Improving oxidation resistance and thermal insulation of thermal barrier coatings by intense pulsed electron beam irradiation

NASA Astrophysics Data System (ADS)

Mei, Xianxiu; Liu, Xiaofei; Wang, Cunxia; Wang, Younian; Dong, Chuang

2012-12-01

In this paper, intense pulsed electron beam was used for the irradiation treatment of 6-8% Y2O3-stablized ZrO2 thermal barrier coating prepared by electron beam-physical vapor deposition to achieve the "sealing" of columnar crystals, thus improving their thermal insulation properties and high temperature oxidation resistance. The electron beam parameters used were: pulse duration 200 μs, electron voltage 15 kV, energy density 3, 5, 8, 15, 20 J/cm2, and pulsed numbers 30. 1050 °C cyclic oxidation and static oxidation experiments were used for the research on oxidation resistance of the coatings. When the energy density of the electron beam was larger than 8 J/cm2, ZrO2 ceramic coating surface was fully re-melted and became smooth, dense and shiny. The coating changed into a smooth polycrystalline structure, thus achieving the "sealing" effect of the columnar crystals. After irradiations with the energy density of 8-15 J/cm2, the thermally grown oxide coating thickness decreased significantly in comparison with non-irradiated coatings, showing that the re-melted coating improved the oxidation resistance of the coatings. The results of thermal diffusivity test by laser flash method showed that the thermal diffusion rate of the irradiated coating was lower than that of the coating without irradiation treatment, and the thermal insulation performance of irradiated coating was improved.

Effects of Co contents on the microstructures and properties of the electrodeposited NiCo–Zr composite coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Fei; Jiang, Chuanhai, E-mail: chuanhaijiang1963@163.com; Zhao, Yuantao

2015-05-15

Highlights: • The novel NiCo–Zr coatings were prepared by electro-deposition. • Surface morphology, crystal structure, grain size and microstrain were examined. • Texture, residual stress and corrosion resistance were investigated. • Addition of Co increased the hardness and corrosion resistance of the coatings. - Abstract: In this study, the NiCo–Zr composite coatings were prepared from the electrolytes with different Co{sup 2+} concentrations by electrodeposition method. The effects of Co contents on the crystal structure, surface morphology, grain size, microstrain and residual stress were examined by X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDX) andmore » atomic force microscope (AFM). The corrosion resistance of the composite coatings was also examined by the potentiodynamic polarization and electrochemical impedance (EIS) measurements. The results revealed that the crystal structures of the coatings were dependent on the Co contents and addition of Co content of 58 wt% resulted in the formation of hexagonal (hcp) Co. The increasing Co contents in the NiCo–Zr composite coatings resulted in the smoother and more compact surface, decreased the grain size and increased the microstrain. The micro-hardness and residual stress also increased with increasing Co contents. The addition of Co increased the corrosion resistance of the NiCo–Zr composite coatings compared with the Ni–Zr coating while the corrosion resistance of the NiCo–Zr composite coatings decreased as the Co contents increased.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lan, Xiaodong; Wu, Hong, E-mail: wuhong927@126.com

Metallic glass composite coatings Ti{sub 45}Cu{sub 41}Ni{sub 9}Zr{sub 5} and Ti{sub 45}Cu{sub 41}Ni{sub 6}Zr{sub 5}Sn{sub 3} (at.%) on a Ti-30Nb-5Ta-7Zr (wt.%) (TNTZ) alloy were prepared by laser cladding. The microstructures of the coatings were characterized by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analyzer (EDXA), and transmission electron microscopy (TEM). Results indicated that the coatings have an amorphous structure embedded with a few nanocrystalline phases and dendrites. A partial substitution of Ni by Sn can improve the glass forming ability of Ti-base metallic glass system, and induce the formation of nano-sized Ni{sub 2}SnTimore » phase during the cyclic laser heating. The tribological behavior of both the substrate and the coatings was investigated in detail. A significant improvement in both the hardness and the wear resistance of the coatings was achieved with the addition of Sn. The relationship between the wear resistance and the microstructures of the coatings was discussed. - Highlights: •Ti-based metallic glass composite coatings were prepared by laser cladding. •The wear resistance is greatly improved by laser cladding of composite coatings. •Substitution of Ni by Sn increases GFA and wear resistance of the coatings. •A good balance of crystalline/amorphous phases improves the wear resistance. •Adhesive wear serves as the dominant wear mechanism of the composite coatings.« less

The Effect of Coatings on the Wear Behavior of Ti6Al4V Alloy Used in Biomedical Applications

NASA Astrophysics Data System (ADS)

Danışman, Ş.; Odabas, D.; Teber, M.

2018-01-01

The properties expected from implant materials are biocompatibility, long service life and wear resistance. The wear resistance of the implant materials varies according to the type of implant, usage area and the movement. The ability of implant material to be more compatible with biological tissues and to increase the useful life depends on the surface properties. Today many different kind of surface modification techniques are applying on medical and dental implant surfaces to improve surface specifications and wear resistance. In this study TiN, TiAlN, TiCN coatings were applied on Ti6Al4V alloy used as implant material by reactive magnetron sputtering method. The wear resistances of uncoated Ti6Al4V alloy and TiN, TiAlN, TiCN coatings were investigated at room temperature under dry conditions. The wear resistance at different load and different sliding rates were compared using an wear tester. The wear losses, wear track widths and friction coefficients of coated and uncoated Ti6Al4V alloys are taken into account for comparison. The results show that a significant improvement in wear resistance of the alloy with the coating is achieved and TiN-coated Ti6Al4V alloy has the highest wear resistance.

Wear resistance of WC/Co HVOF-coatings and galvanic Cr coatings modified by diamond nanoparticles

NASA Astrophysics Data System (ADS)

Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Assenova, E.

2017-02-01

The efforts in the recent 20 years are related to search of ecological solutions in the tribotechnologies for the replacement of galvanic Cr coatings in the contact systems operating under extreme conditions: abrasion, erosion, cavitation, corrosion, shock and vibration loads. One of the solutions is in the composite coatings deposited by high velocity gas-flame process (HVOF). The present paper presents comparative study results for mechanical and tribological characteristics of galvanic Cr coatings without nanoparticles, galvanic Cr coatings modified by diamond nanoparticles NDDS of various concentration 0.6; 10; 15 и 20% obtained under three technological regimes, and composite WC-12Co coating. Comparative results about hardness, wear, wear resistance and friction coefficient are obtained for galvanic Cr-NDDS and WC-12Co coatings operating at equal friction conditions of dry friction on abrasive surface. The WC-12Co coating shows 5.4 to 7 times higher wear resistance compared to the galvanic Cr-NDDS coatings.

Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

NASA Astrophysics Data System (ADS)

Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

2015-12-01

A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

NASA Astrophysics Data System (ADS)

Santa Coloma, P.; Izagirre, U.; Belaustegi, Y.; Jorcin, J. B.; Cano, F. J.; Lapeña, N.

2015-08-01

Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an oxidation process occurred in the vicinity of the alloy's intermetallic particles. The amount of the Zr deposits at these locations increased with coating's formulations without Ti, which provided the best corrosion resistance. The Cr-free conversion coatings developed in this study for the AA7075-T6 and AA2024-T3 alloys do not meet yet the strict requirements of the aircraft industry. However, they significantly improved the corrosion performance with respect to the bare alloys and could be a good starting point for further studies and optimization.

Blanch Resistant and Thermal Barrier NiAl Coating Systems for Advanced Copper Alloys

NASA Technical Reports Server (NTRS)

Raj, Sai V. (Inventor)

2005-01-01

A method of forming an environmental resistant thermal barrier coating on a copper alloy is disclosed. The steps include cleansing a surface of a copper alloy, depositing a bond coat on the cleansed surface of the copper alloy, depositing a NiAl top coat on the bond coat and consolidating the bond coat and the NiAl top coat to form the thermal barrier coating. The bond coat may be a nickel layer or a layer composed of at least one of copper and chromium-copper alloy and either the bond coat or the NiAl top coat or both may be deposited using a low pressure or vacuum plasma spray.

Influence of Surface Pretreatment on the Corrosion Resistance of Cold-Sprayed Nickel Coatings in Acidic Chloride Solution

NASA Astrophysics Data System (ADS)

Scendo, Mieczyslaw; Zorawski, Wojciech; Staszewska-Samson, Katarzyna; Makrenek, Medard; Goral, Anna

2018-03-01

Corrosion resistance of the cold-sprayed nickel coatings deposited on the Ni surface (substrate) without and with abrasive grit-blasting treatment of the substrate was investigated. The corundum powder with different grain sizes was used. The corrosive environment contained an acidic chloride solution. The mechanism of the corrosion of nickel was suggested and discussed. Corrosion electrochemical parameters were determined by electrochemical methods. The corrosion effect of a nickel coating depends on the grain size used to prepare the substrate. The nickel coating after the medium grit-blasting treatment of the substrate was found to be the most corrosion resistant. However, the smallest resistance on the corrosion effect should be attributed to the nickel coating on the substrate after the coarse grit-blasting treatment.

Abrasion resistant heat pipe

DOEpatents

Ernst, D.M.

1984-10-23

A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

Corrosion-protective coatings from electrically conducting polymers

NASA Technical Reports Server (NTRS)

Thompson, Karen Gebert; Bryan, Coleman J.; Benicewicz, Brian C.; Wrobleski, Debra A.

1991-01-01

In a joint effort between NASA Kennedy and LANL, electrically conductive polymer coatings were developed as corrosion protective coatings for metal surfaces. At NASA Kennedy, the launch environment consist of marine, severe solar, and intermittent high acid and/or elevated temperature conditions. Electrically conductive polymer coatings were developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

Corrosion resistance and in-vitro bioactivity of BaO containing Na2O-CaO-P2O5 phosphate glass-ceramic coating prepared on 316 L, duplex stainless steel 2205 and Ti6Al4V

NASA Astrophysics Data System (ADS)

Edathazhe, Akhila B.; Shashikala, H. D.

2018-03-01

The phosphate glass with composition 11Na2O-15BaO-29CaO-45P2O5 was coated on biomedical implant materials such as stainless steel 316 L, duplex stainless steel (DSS) 2205 and Ti6Al4V alloy by thermal enamelling method. The structural properties and composition of glass coated substrates were studied by x-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive x-ray spectroscopy (EDS) analysis. The coatings were partially crystalline in nature with porous structure and pore size varied from micro to nanometer range. The polarization curve was obtained for uncoated and coated substrates from electrochemical corrosion test which was conducted at 37 °C in Hank’s balanced salt solution (HBSS). The corrosion resistance of 316 L substrate increased after coating, whereas it decreased in case of DSS 2205 and Ti6Al4V. The XRD and SEM/EDS studies indicated the bioactive hydroxyapatite (HAp) layer formation on all the coated surfaces after electrochemical corrosion test, which improved the corrosion resistance. The observed electrochemical corrosion behavior can be explained based on protective HAp layer formation, composition and diffusion of ions on glass coated surfaces. The in-vitro bioactivity test was carried out at 37 °C in HBS solution for 14 days under static conditions for uncoated and coated substrates. pH and ion release rate measurements from the coated samples were conducted to substantiate the electrochemical corrosion test. The lower ion release rates of Na+ and Ca2+ from coated 316 L supported its higher electrochemical corrosion resistance among coated samples. Among the uncoated substrates, DSS showed higher electrochemical corrosion resistance. Amorphous calcium-phosphate (ACP) layer formation on all the coated substrates after in-vitro bioactivity test was confirmed by XRD, SEM/EDS and ion release measurements. The present work is a comparative study of corrosion resistance and bioactivity of glass coated and uncoated biomedical implants such as 316 L, DSS and Ti6Al4V.

"Electroless" E-Coating for Magnesium Alloys

NASA Astrophysics Data System (ADS)

Song, Guang-Ling

By utilizing the unique electrochemistry of Mg, a thin organic film can rapidly be deposited on the surface of a Mg alloy by dipping the Mg alloy in a cathodic E-coating bath solution without applying a current or potential. The self-deposited coating is selectively formed on Mg alloy surfaces. Although the "electroless" E-coating pre-film is relatively thin, it can offer sufficient corrosion protection for Mg alloys in a chloride-containing environment. The stability of the film can be significantly improved after curing. The corrosion resistance of the substrate Mg alloy has an important effect on the corrosion protection performance of the coating. The coating is more protective on a corrosion resistant Mg alloy than on a non-corrosion resistant Mg substrate. The coating protection performance is also influenced by the substrate surface condition or pre-treatment process. Wet cleaning + heat-treatment may be a cost-effective surface preparation/treatment for the "electroless" E-coating in industrial applications.

Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2010-01-01

Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

Life cycle assessment of the application of nanoclays in wire coating

NASA Astrophysics Data System (ADS)

Tellaetxe, A.; Blázquez, M.; Arteche, A.; Egizabal, A.; Ermini, V.; Rose, J.; Chaurand, P.; Unzueta, I.

2012-09-01

A life cycle assessment (LCA) is carried out to compare nanoclay-reinforced polymer wire coatings with conventional ones. While the conventional wire coatings contain standard halogen free retardants, in reinforced coatings, montmorillonite (nanoclay) is incorporated into electric cable linings as a rheological agent for an increased resistance to fire. In addition, a reduced load of standard halogen free retardants is obtained. The synergistic effect of the montmorillonite on traditional flame retardant additives (by the formation of a three-dimensional char network) can lead to a revolution in wire production. The application of nanoclays contributes also to anti-dripping effect and flexibility increase [1]. Some producers have already started commercializing wire with nanotechnology-based coating; in the short term the use of nanoclay in wire coating production will probably reach a significant market share replacing traditional formulations. The main aim of this study is to compare the environmental impacts along the life cycle of a traditional wire coating (mineral flame retardants like ATH or MDH in a polymer matrix) with the nanoclay-reinforced wire coating, where the montmorillonite replaces a low percentage of the mineral flame retardant. The system boundaries of the study include the following unit processes: nanoclay production, thermoplastic material and mineral flame retardants production, cable coating manufacturing by extrusion and different end of life scenarios (recycling, incineration and landfill disposal). Whereas nanoreinforced composites have shown and increased fire retardance, the addition of nanomaterials seems to have no significant relevance in the environmental assessment. However, the lack of nano-specific characterization factors for nanomaterials and emission rates associated to the different life cycle stages -mainly in the extrusion and use phase, where accidental combustions can take place- still remains a challenge for realistic life cycle assessment modelling.

Control of volume resistivity in inorganic organic separators

NASA Technical Reports Server (NTRS)

Sheibley, D. W.; Manzo, M. A.

1979-01-01

Control of resistivity in NASA inorganic-organic separators is achieved by incorporating small percentages of high surface area, fine particle silica with other ingredients in the separator coating. The volume resistivity is predictable from the surface area of filler particles in the coating. The approach is applied to two polymer- plasticizer -filler coating systems, where the filler content of each is below the generally acknowledged critical pigment volume concentration of the coating. Application of these coating systems to 0.0254 cm thick (10-mil) fuel cell grade asbestos sheet produces inexpensive, flexible, microporous separators that perform as well as the original inorganic-organic concept, the Astropower separator.

A novel strategy for durable superhydrophobic coating on glass substrate via using silica chains to fix silica particles

NASA Astrophysics Data System (ADS)

Huang, Qi-Zhang; Fang, Yue-Yun; Liu, Peng-Yi; Zhu, Yan-Qing; Shi, Ji-Fu; Xu, Gang

2018-01-01

The practical application of superhydrophobic coatings on glass is usually restricted by their poor wear resistance due to the insufficient adhesion. A double-silica-layered structure was proposed to reinforce the coating adhesion on glass substrate. The wettability, surface morphologies, and chemical composition were investigated by water contact angle measurement, scanning electron microscopy (SEM), and fourier transformed infrared (FTIR) spectroscopy. The prepared superhydrophobic coating displays a good wear-resistance by emery paper and sand abrasion, which also has excellent thermal stability and UV resistance. This strategy shows a bright future for durable superhydrophobic coating on glass.

Control of volume resistivity in inorganic-organic separators. [for alkaline batteries

NASA Technical Reports Server (NTRS)

Sheibley, D. W.; Manzo, M. A.

1980-01-01

Control of resistivity in NASA inorganic-organic separators is achieved by incorporating small percentages of high surface area, fine-particle silica with other ingredients in the separator coating. The volume resistivity appears to be predictable from coating composition, that is, from the surface area of filler particles in the coating. The approach has been applied to two polymer-'plasticizer'-filler coating systems, where the filler content of each is below the generally acknowledged critical pigment volume concentration of the coating. Application of these coating systems to 0.0254 cm thick (10 mil) fuel-cell grade asbestos sheet produces inexpensive, flexible, microporous separators that perform at least as well as the original inorganic-organic concept, the Astropower separator.

Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

NASA Technical Reports Server (NTRS)

Kallenborn, K. J.; Emmons, J. R.

1995-01-01

Chromic acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process.

Plasma-assisted deposition of microcapsule containing Aloe vera extract for cosmeto-textiles

NASA Astrophysics Data System (ADS)

Nascimento do Carmo, S.; Zille, A.; Souto, A. P.

2017-10-01

Dielectric Barrier Discharge (DBD) atmospheric-pressure plasma was employed to enhance the deposition of commercial microcapsules (MCs) containing Aloe vera extract onto a cotton/polyester (50:50) fabric. DBD conditions were optimized in term of energy dosage and contact angle. The MCs were applied by padding and printing methods and the coatings were characterized in terms of SEM and FTIR. MCs display a spherical shape with size between 2 and 8 μm with an average wall thickness of 0.5 μm. The MCs applied by printing and pretreated with a plasma dosage of 1.6 kW m2 min-1 showed the best results with an increased adhesion of 200% and significant penetration of MCs into the fibres network. Plasma printed fabric retained 230% more MCs than untreated fabric after 10 washing cycles. However, the coating resistance between unwashed and washed samples was only improved by 5%. Considering the fact that no binder or crosslinking agents were used, the DBD plasma-assisted deposition of MCs revealed to be a promising environmental safe and low cost coating technology.

Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure and method of processing

DOEpatents

Brown, Jr., Jesse J.; Hirschfeld, Deidre A.; Li, Tingkai

1993-12-07

Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure are created using sol-gel processes. The processes have particular application in creating calcium magnesium zirconium phosphate, CMZP, coatings and foams.

Highly stable silica-coated manganese ferrite nanoparticles as high-efficacy T2 contrast agents for magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Ahmad, Ashfaq; Bae, Hongsub; Rhee, Ilsu

2018-05-01

Highly stable silica-coated manganese ferrite nanoparticles were fabricated for application as magnetic resonance imagining (MRI) contrast agents. The manganese ferrite nanoparticles were synthesized using a hydrothermal technique and coated with silica. The particle size was investigated using transmission electron microscopy and was found to be 40-60 nm. The presence of the silica coating on the particle surface was confirmed by Fourier transform infrared spectroscopy. The crystalline structure was investigated by X-ray diffraction, and the particles were revealed to have an inverse spinel structure. Superparamagnetism was confirmed by the magnetic hysteresis curves obtained using a vibrating sample magnetometer. The efficiency of the MRI contrast agents was investigated by using aqueous solutions of the particles in a 4.7 T MRI scanner. The T1 and T2 relaxivities of the particles were 1.42 and 60.65 s-1 mM-1, respectively, in water. The ratio r2/r1 was 48.91, confirming that the silica-coated manganese ferrite nanoparticles were suitable high-efficacy T2 contrast agents.

Coating agents affected toward magnetite nanoparticles properties

NASA Astrophysics Data System (ADS)

Petcharoen, Karat; Sirivat, Anuvat

2012-02-01

Magnetite nanoparticles --MNPs-- are innovative materials used in biological and medical applications. They respond to magnetic field through the superparamagnetic behavior at room temperature. In this study, the MNPs were synthesized via the chemical co-precipitation method using various coating agents. Fatty acids, found naturally in the animal fats, can be used as a coating agent. Oleic acid and hexanoic acid were chosen as the surface modification agents to study the improvement in the suspension of MNPs in water and the magnetite properties. Suspension stability, particle size, and electrical conductivity of MNPs are critically affected by the modification process. The well-dispersed MNPs in water can be improved by the surface modification and the oleic acid coated MNPs possess excellent suspension stability over 1 week. The particle size of MNPs increases up to 40 nm using oleic acid coated MNPs. The electrical conductivity of the smallest particle size is 1.3x10-3 S/cm, which is 5 times higher than that of the largest particle, suggesting potential applications as a biomedical material under both of the electrical and magnetic fields.

Creation of Vapor/Gas Impermeable Coatings for CB Hardening of Existing Structures

DTIC Science & Technology

2013-04-05

TEST REPORT for POLYMERight, Inc. Coating Agent Testing Prepared for: POLYMERight, Inc. Prepared by: Edward Soja Brian Blackstone ...POLYMERight, Inc. Mr. Alex Vainer 4404-C Enterprise Place Fremont, CA 94538 Prepared by: Edward Soja Brian Blackstone Battelle 505 King Ave...Inc. Coating Agent Testing 24 7.0 Contacts Contact Role Location Phone Brian Blackstone Program Manager Battelle, West Jefferson (614) 424

Method for depositing an oxide coating

NASA Technical Reports Server (NTRS)

Mcdonald, G. E. (Inventor)

1982-01-01

A metal oxide coating is plated onto a metal substrate at the cathode from an acid solution which contains an oxidizing agent. The process is particularly useful for producing solar panels. Conventional plating at the cathode avoids the presence of oxidizing agents. Coatings made in accordance with the invention are stable both at high temperatures and while under the influence of high photon flux in the visible range.

Characterization, Corrosion Resistance, and Cell Response of High-Velocity Flame-Sprayed HA and HA/TiO2 Coatings on 316L SS

NASA Astrophysics Data System (ADS)

Singh, Tejinder Pal; Singh, Harpreet; Singh, Hazoor

2012-09-01

The main aim of this study is to evaluate corrosion and biocompatibility behavior of thermal spray hydroxyapatite (HA) and hydroxyapatite/titania bond (HA/TiO2)-coated 316L stainless steel (316L SS). In HA/TiO2 coatings, TiO2 was used as a bond coat between HA top coat and 316L SS substrate. The coatings were characterized by x-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy, and corrosion resistance determined for the uncoated substrate and the two coatings. The biological behavior was investigated by the cell culture studies using osteosarcoma cell line KHOS-NP (R-970-5). The corrosion resistance of the steel was found to increase after the deposition of the HA and HA/TiO2 bond coatings. Both HA, as well as, HA/TiO2 coatings exhibit excellent bond strength of 49 and 47 MPa, respectively. The cell culture studies showed that HA-coated 316L SS specimens appeared more biocompatible than the uncoated and HA/TiO2-coated 316L SS specimens.

High Temperature Thermal Stability and Oxidation Resistance of Magnetron-sputtered Homogeneous CrAlON Coatings on 430 Steel

NASA Astrophysics Data System (ADS)

Kayani, A.; Wickey, K. J.; Nandasiri, M. I.; Moore, A.; Garratt, E.; AlFaify, S.; Gao, X.; Smith, R. J.; Buchanan, T. L.; Priyantha, W.; Kopczyk, M.; Gannon, P. E.; Gorokhovsky, V. I.

2009-03-01

The requirements of low cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigated the performance of steel plates with homogenous coatings of CrAlON (oxynitrides). The coatings were deposited using RF magnetron sputtering, with Ar as a sputtering gas. Oxygen in these coatings was not intentionally added. Oxygen might have come through contaminated nitrogen gas bottle, leak in the chamber or from the partial pressure of water vapors. Nitrogen was added during the growth process to get oxynitride coating. The Cr/Al composition ratio in the coatings was varied in a combinatorial approach. The coatings were subsequently annealed in air for up to 25 hours at 800° C. The composition of the coated plates and the rate of oxidation were characterized using Rutherford backscattering (RBS) and nuclear reaction analysis (NRA). From our results, we conclude that Al rich coatings are more susceptible to oxidation than Cr rich coatings.

Corrosion resistant neutron absorbing coatings

DOEpatents

Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

2012-05-29

A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

Corrosion resistant neutron absorbing coatings

DOEpatents

Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

2013-11-12

A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

Antibacterial property of fabrics coated by magnesium-based brucites

NASA Astrophysics Data System (ADS)

Wang, Ying; Sha, Lin; Zhao, Jiao; Li, Qian; Zhu, Yimin; Wang, Ninghui

2017-04-01

A kind of environmental-friendly magnesium-based antibacterial agent was reported for the first time, which was composited by brucites with different particle sizes. The antibacterial fabrics were produced by coating the magnesium-based antibacterial agents on the 260T polyester pongee fabrics with waterborne polyurethane. The coating process was simple, low-cost, and harmless to human health and environment. Characteristics of the antibacterial agents and fabrics were studied by particulate size distribution analyzer (PSDA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results demonstrated that the coating layer was covered tightly on the fabrics and compositing of different particles by a certain proportion made full filling of the coating layer. Meanwhile, compositing did not change the structure of brucites. The antibacterial fabrics presented strong antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with the reduction percentage of 96.6% and 100%, respectively, and the antibacterial fabrics attained excellent washing durability.

Adsorption study of a macro-RAFT agent onto SiO2-coated Gd2O3:Eu3+ nanorods: Requirements and limitations

NASA Astrophysics Data System (ADS)

Zou, Hua; Melro, Liliana; de Camargo Chaparro, Thaissa; de Souza Filho, Isnaldi Rodrigues; Ananias, Duarte; Bourgeat-Lami, Elodie; dos Santos, Amilton Martins; Barros-Timmons, Ana

2017-02-01

The use of a macromolecular RAFT (macro-RAFT) agent to encapsulate anisotropic nano-objects via emulsion polymerization is an emerging route to prepare polymer/inorganic colloidal nanocomposites. However, a number of requirements have to be fulfilled. This work aims at highlighting the effects of the preparative procedure and dispersion method on the amount of macro-RAFT agent adsorbed onto SiO2-coated Gd2O3:Eu3+ nanorods. The adsorption of macro-RAFT agent was studied using the depletion method with UV-vis spectrophotometry. Measurements were performed at a fixed concentration of nanorods and varying concentrations of the macro-RAFT agent in aqueous dispersion at room temperature. The adsorption isotherms showed that for the same initial macro-RAFT agent concentration, the highest adsorption capacity of the macro-RAFT agent on nanorods was usually achieved for non-calcined thin SiO2-coated nanorods under mild bath sonication.

Formation of high heat resistant coatings by using gas tunnel type plasma spraying.

PubMed

Kobayashi, A; Ando, Y; Kurokawa, K

2012-06-01

Zirconia sprayed coatings are widely used as thermal barrier coatings (TBC) for high temperature protection of metallic structures. However, their use in diesel engine combustion chamber components has the long run durability problems, such as the spallation at the interface between the coating and substrate due to the interface oxidation. Although zirconia coatings have been used in many applications, the interface spallation problem is still waiting to be solved under the critical conditions such as high temperature and high corrosion environment. The gas tunnel type plasma spraying developed by the author can make high quality ceramic coatings such as Al2O3 and ZrO2 coating compared to other plasma spraying method. A high hardness ceramic coating such as Al2O3 coating by the gas tunnel type plasma spraying, were investigated in the previous study. The Vickers hardness of the zirconia (ZrO2) coating increased with decreasing spraying distance, and a higher Vickers hardness of about Hv = 1200 could be obtained at a shorter spraying distance of L = 30 mm. ZrO2 coating formed has a high hardness layer at the surface side, which shows the graded functionality of hardness. In this study, ZrO2 composite coatings (TBCs) with Al2O3 were deposited on SS304 substrates by gas tunnel type plasma spraying. The performance such as the mechanical properties, thermal behavior and high temperature oxidation resistance of the functionally graded TBCs was investigated and discussed. The resultant coating samples with different spraying powders and thickness are compared in their corrosion resistance with coating thickness as variables. Corrosion potential was measured and analyzed corresponding to the microstructure of the coatings. High Heat Resistant Coatings, Gas Tunnel Type Plasma Spraying, Hardness,

Fabrication of Refractive Index Tunable Coating with Moisture-Resistant Function for High-Power Laser Systems Based on Homogeneous Embedding of Surface-Modified Nanoparticles.

PubMed

Yang, Wei; Lei, Xiangyang; Hui, Haohao; Zhang, Qinghua; Deng, Xueran

2018-05-07

Moisture-resistant silicone coatings were prepared on the surface of potassium dihydrogen phosphate (KDP) crystal by means of spin-coating, in which hydrophobic-modified SiO₂ nanoparticles were embedded in a certain proportion. The refractive index of such coating can be tuned arbitrarily in the range of 1.21⁻1.44, which endows the KDP optical component with excellent transmission capability as well as the moisture proof effect. A dual-layer anti-reflective coating system was obtained by covering this silicone coating with a porous SiO₂ coating which is specially treated to enhance the moisture resistance. Transmittance of such a dual-layer coating system could reach 99.60% and 99.62% at 1064 nm and 532 nm, respectively, by precisely matching the refractive index of both layers. Furthermore, the long-term stability of this coating system has been verified at high humidity ambient of 80% RH for 27 weeks.

Microstructure and wear resistance of Ti-Cu-N composite coating prepared via laser cladding/laser nitriding technology on Ti-6Al-4V alloy

NASA Astrophysics Data System (ADS)

Yang, Yuling; Cao, Shiyin; Zhang, Shuai; Xu, Chuan; Qin, Gaowu

2017-07-01

Ti-Cu-N coatings with three different Cu contents on Ti-6Al-4V alloy (TC4) were obtained via laser cladding together with laser nitriding (LC/LN) technology. Phase constituents, microstructure, microhardness, and wear resistance of the coatings were investigated. The evolution of the coefficients of friction for the three coatings was measured under dry sliding conditions as a function of the revolutions until the coating failure. The results show that the coatings are mainly composed of TiN, CuTi3 and some TiO6 phases dispersed in the matrix. A good metallurgical bonding between the coating and substrate has been successfully obtained. The prepared Ti-Cu-N composite coatings almost doubly enhance the microhardness of the TC4 alloy and reduce the friction down to 1/4-1/2 of the TC4 alloy, and thus significantly improve the wear resistance. The coefficient of friction depends on the Cu content in the coating.

Effect of ceramic coating by aerosol deposition on abrasion resistance of a resin composite material.

PubMed

Taira, Yohsuke; Hatono, Hironori; Mizukane, Masahiro; Tokita, Masahiro; Atsuta, Mitsuru

2006-12-01

Aerosol deposition (AD coating) is a novel technique to coat solid substances with a ceramic film. The purpose of the present study was to investigate the effect of AD coating on abrasion resistance of a resin composite material. A 5-microm-thick aluminum oxide layer was created on the polymerized resin composite. The specimen was cyclically abraded using a toothbrush abrasion simulator for 100,000 cycles. Abraded surface was then measured with a profilometer to determine the average roughness (Ra) and maximum roughness (Rmax). It was found that abrasion cycling increased the Ra value of the No-AD-coating group, but decreased the Ra and Rmax values of the AD coating group. Moreover, the AD coating group showed significantly smaller Ra and Rmax values after 100,000 abrasion cycles as compared to the No-coating control group. Microscopic observation supported these findings. In conclusion, the resistance of the resin composite against toothbrush abrasion was improved by AD coating.

Process optimization for particle removal on blank chrome mask plates in preparation for resist application

NASA Astrophysics Data System (ADS)

Osborne, Stephen; Smith, Eryn; Woster, Eric; Pelayo, Anthony

2002-03-01

As integrated circuits require smaller lines to provide the memory and processing capability for tomorrow's marketplace, the photomask industry is adopting higher contrast resists to improve photomask lithography. Photomask yield for several high-contrast resist recipes may be improved by coating masks at the mask shop. When coating at a mask shop, an effective method is available that uses coat/bake cluster tools to ensure blanks are clean prior to coating. Many high-contrast resists are available, and some are more susceptible to time-dependent performance factors than conventional resists. One of these factors is the time between coating and writing. Although future methods may reduce the impact of this factor, one current trend is to reduce this time by coating plates at the mask shop just prior to writing. Establishing an effective process to clean blanks prior to coating is necessary for product quality control and is a new task that is critical for maskmakers who previously purchased mask plates but have decided to begin coating them within their facility. This paper provides a strategy and method to be used within coat/bake cluster tools to remove particle contamination from mask blanks. The process uses excimer-UV ionizing radiation and ozone to remove organic contaminants, and then uses a wet process combined with megasonic agitation, surfactant, and spin forces. Megasonic agitation with surfactant lifts up particles, while the convective outflow of water enhances centripetal shear without accumulating harmful charge.

Tribological Behavior and Corrosion Resistance of Electroless Ni-B-W Coatings

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Arkadeb; Barman, Tapan Kumar; Sahoo, Prasanta

The present study considers the tribological behavior and corrosion resistance of electroless Ni-B-W coatings deposited on AISI 1040 steel substrates. Coating is characterized using scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction technique. In as-deposited condition, coatings are found to be amorphous. On heat treatment, precipitation of crystalline Ni (1 1 1) and its borides take place. For as-deposited coating, the microhardness is obtained as ˜759HV100 which increases to ˜1181HV100 and ˜1098HV100 when heat treated at 350∘C and 450∘C, respectively. Incorporation of W in Ni-B coating results in an increase of hardness by 89HV100 in as-deposited condition. Heat treatment also results in increase in crystallite size of Ni (1 1 1). Wear rate and coefficient of friction (COF) of the coatings are evaluated on a pin-on-disc setup under both dry and lubricated sliding conditions. Wear resistance is observed to improve on heat treatment with an increase in crystallite size while COF deteriorates. However, in as-deposited condition, wear rate and COF of Ni-B-W coatings improve by ˜5 and ˜3 times, respectively, compared with Ni-B coatings. Wear and friction performance of the coatings are enhanced under lubrication due to the columnar structure of the coatings that retain lubricants. Corrosion resistance of Ni-B-W coating in 3.5% NaCl solution gets improved on heat treatment.

Passivation Behavior of Fe-Based Amorphous Coatings Prepared by High-Velocity Air/Oxygen Fuel Processes

NASA Astrophysics Data System (ADS)

Ma, H. R.; Li, J. W.; Chang, C. T.; Wang, X. M.; Li, R. W.

2017-12-01

Corrosion resistance and passivation behavior of Fe63Cr8Mo3.5Ni5P10B4C4Si2.5 amorphous coatings prepared by the activated combustion high-velocity air fuel (AC-HVAF) and high-velocity oxygen fuel (HVOF) processes have been studied in detail by cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, cathodic polarization and Mott-Schottky approach. The AC-HVAF coating shows higher corrosion resistance than the HVOF coating in 3.5 wt.% NaCl solution, as evidenced by its lower corrosion current density and passive current density. It is found that the superior corrosion resistance of the AC-HVAF coating is attributed to the enhanced formation of a dense passive film with less defective structure, higher pitting resistance and passivity stability, as well as stronger repassivity.

Study of coatings for improved fire and decay resistance of mine timbers

NASA Technical Reports Server (NTRS)

Baum, B.

1977-01-01

The purpose of this program was to find a fire- and rot-retardant polymer/fungicide reaction product for coating mine timbers. Fire-retardant polymers were screened as films and coatings on fir wood. Curable polyimide appeared to be flame retardant and evolved a minimum of fumes when exposed to a flame. Several organic and metal, low toxicity, fungicides were reacted with the polyimide in-situ on the wood. These coated samples were screened for fungus resistance. All formulations rated well - even the polyimide film without additives was fungicidal. The fir wood control itself resisted internal damage during the ten weeks of fungus exposure. A more severe test for fungus resistance will be required.

Fabrication of oxide dispersion strengthened bond coats with low Al 2O 3 content [Fabrication of ODS bond coats with low Al 2O 3 content

DOE PAGES

Bergholz, Jan; Pint, Bruce A.; Unocic, Kinga A.; ...

2017-03-23

Here, nanoscale oxide dispersions have long been used to increase the oxidation and wear resistance of alloys used as bond coatings in thermal barrier coatings. Their manufacturing via mechanical alloying is often accompanied by difficulties regarding their particle size, homogeneous distribution of the oxide dispersions inside the powder, involving considerable costs, due to cold welding of the powder during milling. A significant improvement in this process can be achieved by the use of process control agent (PCA) to achieve the critical balance between cold welding and fracturing, thereby enhancing the process efficiency. In this investigation, the influence of the organicmore » additive stearic acid on the manufacturing process of Al 2O 3-doped CoNiCrAlY powder was investigated. Powders were fabricated via mechanical alloying at different milling times and PCA concentrations. The results showed a decrease in particle size, without hindering the homogeneous incorporation of the oxide dispersions. Two powders manufactured with 0.5 and 1.0 wt.% PCA were deposited by high velocity oxygen fuel (HVOF) spraying. Results showed that a higher content of elongated particles in the powder with the higher PCA content led to increased surface roughness, porosity and decreased coating thickness, with areas without embedded oxide particles.« less

Improvement of interfacial interactions using natural polyphenol-inspired tannic acid-coated nanoclay enhancement of soy protein isolate biofilms

NASA Astrophysics Data System (ADS)

Wang, Zhong; Kang, Haijiao; Zhang, Wei; Zhang, Shifeng; Li, Jianzhang

2017-04-01

In this study, a novel and economic surface modification technique for montmorillonite (MMT) nanosheets, a biocompatible coupling cross-linking agent, was developed on an attempt at improving the interfacial adhesion with soy protein isolate (SPI) matrix. Inspired by natural polyphenol, the "green dip-coating" method using tannic acid (TA) to surface-modify MMT (TA@MMT). SPI nanocomposite films modified with MMT or TA@MMT, as well as the control ones, were prepared via the casting method. The TA layer was successfully coated on the MMT surface through the (FeIII) ions coordination chemistry and the synthetic samples were characterized by the Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The compatibility and interfacial interactions between modified MMT and SPI matrix were greatly enhanced by the TA-FeIII coating on the MMT surface. The mechanical properties, water resistance, and thermal stability of the resultant biofilm were increased accordingly. Compared with that of the unmodified SPI film, the tensile strength of the nanocomposite films modified by the green dip-coating was increased by 113.3%. These SPI-based nanocomposite films showed the favorable potential in terms of food packing applications due to their efficient barriers to water vapor and UV and/or visible light.

Influence of Applied Voltage and Film-Formation Time on Microstructure and Corrosion Resistance of Coatings Formed on Mg-Zn-Zr-Ca Bio-magnesium Alloy

NASA Astrophysics Data System (ADS)

Yandong, Yu; Shuzhen, Kuang; Jie, Li

2015-09-01

The influence of applied voltage and film-formation time on the microstructure and corrosion resistance of coatings formed on a Mg-Zn-Zr-Ca novel bio-magnesium alloy has been investigated by micro-arc oxidation (MAO) treatment. Phase composition and microstructure of as-coated samples were analyzed by the x-ray diffraction, energy dispersive x-ray spectroscopy and scanning electron microscopy. And the porosity and average of micro-pore aperture of the surface on ceramic coatings were analyzed by general image software. Corrosion microstructure of as-coated samples was caught by a microscope digital camera. The long-term corrosion resistance of as-coated samples was tested in simulated body fluid for 30 days. The results showed that the milky white smooth ceramic coating formed on the Mg-Zn-Zr-Ca novel bio-magnesium alloy was a compound of MgO, Mg2SiO4 and MgSiO3, and its corrosion resistance was significantly improved compared with that of the magnesium substrate. In addition, when the MAO applied voltage were 450 V and 500 V and film-formation time were 9 min and 11 min, the surface micro-morphology and the corrosion resistance of as-coated samples were relatively improved. The results provided a theoretical foundation for the application of the Mg-Zn-Zr-Ca novel bio-magnesium alloy in biomedicine.

Optoelectronic properties and interfacial durability of CNT and ITO on boro-silicate glass and PET substrates with nano- and heterostructural aspects

NASA Astrophysics Data System (ADS)

Park, Joung-Man; Wang, Zuo-Jia; Kwon, Dong-Jun; DeVries, Lawrence

2011-02-01

Nano- and hetero-structures of carbon nanotube (CNT) and indium tin oxide (ITO) can control significantly piezoelectric and optoelectronic properties in Microelectromechanical Systems (MEMS) as sensing and actuator under cyclic loading. Optimized preparing conditions were obtained for multi-functional purpose of the specimen by obtaining the best dispersion and turbidity in the solution. Optical transmittance and electrical properties were investigated for CNT and ITO dipping and spraying coating on boro-silicate glass and polyethylene terephthalate (PET) substrates by electrical resistance measurement under cyclic loading and wettability test. Uniform dip-coating was performed using Wilhelmy plate method due to its simple and convenience. Spraying coating was applied to the specimen additionally. The change in the electrical resistance and optical properties of coated layer were mainly dependent upon the number of dip-coating, the concentration of CNT and ITO solutions, and the surface treatment condition. Electric properties of coating layers were measured using four-point probe method, and surface resistance was calculated using a dual configuration method. Optical transmittance of CNT and ITO coated PET film was also evaluated using UV spectrum. Surface energy and their hydrophilic and hydrophobic properties of CNT and ITO coated substrates were investigated by wettability test via static and dynamic contact angle measurements. As the elapsing time of cyclic loading passed, the stability of surface resistance and thus comparative interfacial adhesion between coated layer and substrates was evaluated to compare the thermodynamic work of adhesion, Wa. As dip-coating number increased, surface resistance of coated CNT decreased, whereas the transmittance decreased step-by-step due to the thicker CNT and ITO networked layer. Nano- and heterostructural effects of CNT and ITO solution on the optical and electrical effects have been studied continuously.

Thermal stability and chemical resistance of (Ti,Al)N-Cu and (Ti,Al)N-Ni metal-ceramic nanostructured coatings

NASA Astrophysics Data System (ADS)

Belov, D. S.; Blinkov, I. V.; Volkhonskii, A. O.; Kuznetsov, D. V.; Kiryukhantsev-Korneev, F. V.; Pustov, Yu. A.; Sergevnin, V. S.

2016-12-01

This work represents the results of research on thermal stability, oxidation resistance at temperatures of up to 800 °C and electrochemical behaviour of (Ti,Al)N-(∼3 at.%)Cu and (Ti,Al)N-(∼8 at.%)Ni nanocrystalline coatings in acidic and alkaline media. The coatings were deposited by the arc-PVD method with a thickness of approximately 4 μm and crystallite size of less than 20 nm. It has been demonstrated that the composition and properties of the coating structures do not change when the coatings are heated in 10-4 Pa vacuum at temperatures of 600, 700 °C for 1.5 h. Heating up to 800 °C caused an increase of crystallite size and reduction microstrain in the crystal lattice of the ceramic phase. The process is accompanied by deterioration of the coating hardness from 48 to 52 to 33-36 GPa. The (Ti,Al)N-Cu and (Ti,Al)N-Ni metal-ceramic nanostructured coatings are characterized by heat resistance up to the temperatures of 700 and 800 °C respectively. The coatings under study have tendency for self-passivation and resistance to pitting corrosion.

Enhancement of oxidation resistance of graphite foams by polymer derived-silicon carbide coating for concentrated solar power applications

DOE PAGES

Kim, T.; Singh, D.; Singh, M.

2015-05-01

Graphite foam with extremely high thermal conductivity has been investigated to enhance heat transfer of latent heat thermal energy storage (LHTES) systems. However, the use of graphite foam for elevated temperature applications (>600 °C) is limited due to poor oxidation resistance of graphite. In the present study, oxidation resistance of graphite foam coated with silicon carbide (SiC) was investigated. A pre-ceramic polymer derived coating (PDC) method was used to form a SiC coating on the graphite foams. Post coating deposition, the samples were analyzed by scanning electron microscopy and energy dispersive spectroscopy. The oxidation resistance of PDC-SiC coating was quantifiedmore » by measuring the weight of the samples at several measuring points. The experiments were conducted under static argon atmosphere in a furnace. After the experiments, oxidation rates (%/hour) were calculated to predict the lifetime of the graphite foams. The experimental results showed that the PDC-SiC coating could prevent the oxidation of graphite foam under static argon atmosphere up to 900 °C.« less

Microstructure and wear resistance of one-step in-situ synthesized TiN/Al composite coatings on Ti6Al4V alloy by a laser nitriding process

NASA Astrophysics Data System (ADS)

Fu, Yao; Zhang, Xian-Cheng; Sui, Jian-Feng; Tu, Shan-Tung; Xuan, Fu-Zhen; Wang, Zheng-Dong

2015-04-01

The aim of this paper was to develop a one-step in situ method to synthesize the TiN reinforced Al metallic matrix composite coatings on Ti6Al4V alloy. In this method, the Al powder and nitrogen gas were simultaneously fed into feeding nozzle during a laser nitriding process. The microstructure, microhardness and sliding wear resistance of TiN/Al coatings synthesized at different laser powers in laser nitriding were investigated. Results showed that the crack- and pore-free coatings can be made through the proposed method. However, the morphologies and distribution of TiN dendrites and wear resistance of coatings were strongly dependent on laser power used in nitriding. With increasing the laser power, the amount and density of massive TiN dendritic structure in the coating decreased and the elongated and narrow dendrites increased, leading to the increment of wear resistance of coating. When the laser power is high, the convectional flow pattern of the melt pool can be seen near the bottom of pool.

Degradation of graphene coated copper in simulated proton exchange membrane fuel cell environment: Electrochemical impedance spectroscopy study

NASA Astrophysics Data System (ADS)

Ren, Y. J.; Anisur, M. R.; Qiu, W.; He, J. J.; Al-Saadi, S.; Singh Raman, R. K.

2017-09-01

Metallic materials are most suitable for bipolar plates of proton exchange membrane fuel cell (PEMFC) because they possess the required mechanical strength, durability, gas impermeability, acceptable cost and are suitable for mass production. However, metallic bipolar plates are prone to corrosion or they can passivate under PEMFC environment and interrupt the fuel cell operation. Therefore, it is highly attractive to develop corrosion resistance coating that is also highly conductive. Graphene fits these criteria. Graphene coating is developed on copper by chemical vapor deposition (CVD) with an aim to improving corrosion resistance of copper under PEMFC condition. The Raman Spectroscopy shows the graphene coating to be multilayered. The electrochemical degradation of graphene coated copper is investigated by electrochemical impedance spectroscopy (EIS) in 0.5 M H2SO4 solution at room temperature. After exposure to the electrolyte for up to 720 h, the charge transfer resistance (Rt) of the graphene coated copper is ∼3 times greater than that of the bare copper, indicating graphene coatings could improve the corrosion resistance of copper bipolar plates.

Toughening Fe-based Amorphous Coatings by Reinforcement of Amorphous Carbon.

PubMed

Wang, Wei; Zhang, Cheng; Zhang, Zhi-Wei; Li, Yi-Cheng; Yasir, Muhammad; Wang, Hai-Tao; Liu, Lin

2017-06-22

Toughening of Fe-based amorphous coatings meanwhile maintaining a good corrosion resistance remains challenging. This work reports a novel approach to improve the toughness of a FeCrMoCBY amorphous coating through in-situ formation of amorphous carbon reinforcement without reducing the corrosion resistance. The Fe-based composite coating was prepared by high velocity oxy-fuel (HVOF) thermal spraying using a pre-mixed Fe-based amorphous/nylon-11 polymer feedstock powders. The nylon-11 powders were in-situ carbonized to amorphous carbon phase during thermal spraying process, which homogeneously distributed in the amorphous matrix leading to significant enhancement of toughness of the coating. The mechanical properties, including hardness, impact resistance, bending and fatigue strength, were extensively studied by using a series of mechanical testing techniques. The results revealed that the composite coating reinforced by amorphous carbon phase exhibited enhanced impact resistance and nearly twice-higher fatigue strength than that of the monolithic amorphous coating. The enhancement of impact toughness and fatigue properties is owed to the dumping effect of the soft amorphous carbon phase, which alleviated stress concentration and decreased crack propagation driving force.

Corrosion resistance of BIS 2062-grade steel coated with nano-metal-oxide mixtures of iron, cerium, and titanium in the marine environment

NASA Astrophysics Data System (ADS)

Ashraf, P. Muhamed; Anuradha, R.

2018-02-01

BIS 2062-grade carbon steel is extensively used for fishing boat construction. The steel is highly susceptible to corrosion on the hull and welding joints under marine environment. Here, we demonstrate the application of a novel multifunctional nano-metal-oxide mixture comprised of iron, titanium, and cerium as a marine coating to prevent corrosion. The electrochemical performance of nano-metal-oxide mixture coatings, applied over boat-building steel, was evaluated at 3.5% NaCl medium. The nano-mixture surface coatings showed an efficient corrosion resistance with increased polarization resistance of 6043 Ω cm2 and low corrosion current density of 3.53 × 10-6 A cm-2. The electrochemical impedance spectral data exhibited improvement in the polarization resistance of outermost surface and internal layers. The coating responded faster recovery to normal state when subjected to an induced stress over the coating. The nano-material in the coating behaves as a semiconductor; this enhanced electronic activity over the surface of the steel.

Inhibition of Sulfide Mineral Oxidation by Surface Coating Agents: Batch

NASA Astrophysics Data System (ADS)

Choi, J.; Ji, M. K.; Yun, H. S.; Park, Y. T.; Gee, E. D.; Lee, W. R.; Jeon, B.-H.

2012-04-01

Mining activities and mineral industries have impacted on rapid oxidation of sulfide minerals such as pyrite (FeS2) which leads to Acid Mine Drainage (AMD) formation. Some of the abandoned mines discharge polluted water without proper environmental remediation treatments, largely because of financial constraints in treating AMD. Magnitude of the problem is considerable, especially in countries with a long history of mining. As metal sulfides become oxidized during mining activities, the aqueous environment becomes acid and rich in many metals, including iron, lead, mercury, arsenic and many others. The toxic heavy metals are responsible for the environmental deterioration of stream, groundwater and soils. Several strategies to remediate AMD contaminated sites have been proposed. Among the source inhibition and prevention technologies, microencapsulation (coating) has been considered as a promising technology. The encapsulation is based on inhibition of O2 diffusion by surface coating agent and is expected to control the oxidation of pyrite for a long time. Potential of several surface coating agents for preventing oxidation of metal sulfide minerals from both Young-Dong coal mine and Il-Gwang gold mine were examined by conducting batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH2PO4, MgO and KMnO4 as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H2O2 or NaClO). Batch experiments with Young-Dong coal mine samples showed least SO42- production in presence of KMnO4 (16% sulfate production compared to no surface coating agents) or cement (4%) within 8 days. In the case of Il-Gwang mine samples, least SO42- production was observed in presence of KH2PO4 (8%) or cement (2%) within 8 days. Field-scale pilot tests at Il-Gwang site also showed that addition of KH2PO4 decreased sulfate production from 200 to 13 mg L-1 and reduced Cu and Mn from 8 and 3 mg L-1 to below the detection limits, respectively. The experimental results suggested that the amendment of surface coating agents can be a promising alternative for inhibition of sulfide oxidation at AMD sites.

Graphene Oxide-Based Nanocomposites Decorated with Silver Nanoparticles as an Antibacterial Agent

NASA Astrophysics Data System (ADS)

Jaworski, Sławomir; Wierzbicki, Mateusz; Sawosz, Ewa; Jung, Anna; Gielerak, Grzegorz; Biernat, Joanna; Jaremek, Henryk; Łojkowski, Witold; Woźniak, Bartosz; Wojnarowicz, Jacek; Stobiński, Leszek; Małolepszy, Artur; Mazurkiewicz-Pawlicka, Marta; Łojkowski, Maciej; Kurantowicz, Natalia; Chwalibog, André

2018-04-01

One of the most promising methods against drug-resistant bacteria can be surface-modified materials with biocidal nanoparticles and nanocomposites. Herein, we present a nanocomposite with silver nanoparticles (Ag-NPs) on the surface of graphene oxide (GO) as a novel multifunctional antibacterial and antifungal material. Ultrasonic technologies have been used as an effective method of coating polyurethane foils. Toxicity on gram-negative bacteria ( Escherichia coli), gram-positive bacteria ( Staphylococcus aureus and Staphylococcus epidermidis), and pathogenic yeast ( Candida albicans) was evaluated by analysis of cell morphology, assessment of cell viability using the PrestoBlue assay, analysis of cell membrane integrity using the lactate dehydrogenase assay, and reactive oxygen species production. Compared to Ag-NPs and GO, which have been widely used as antibacterial agents, our nanocomposite shows much higher antimicrobial efficiency toward bacteria and yeast cells.

Graphene Oxide-Based Nanocomposites Decorated with Silver Nanoparticles as an Antibacterial Agent.

PubMed

Jaworski, Sławomir; Wierzbicki, Mateusz; Sawosz, Ewa; Jung, Anna; Gielerak, Grzegorz; Biernat, Joanna; Jaremek, Henryk; Łojkowski, Witold; Woźniak, Bartosz; Wojnarowicz, Jacek; Stobiński, Leszek; Małolepszy, Artur; Mazurkiewicz-Pawlicka, Marta; Łojkowski, Maciej; Kurantowicz, Natalia; Chwalibog, André

2018-04-23

One of the most promising methods against drug-resistant bacteria can be surface-modified materials with biocidal nanoparticles and nanocomposites. Herein, we present a nanocomposite with silver nanoparticles (Ag-NPs) on the surface of graphene oxide (GO) as a novel multifunctional antibacterial and antifungal material. Ultrasonic technologies have been used as an effective method of coating polyurethane foils. Toxicity on gram-negative bacteria (Escherichia coli), gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), and pathogenic yeast (Candida albicans) was evaluated by analysis of cell morphology, assessment of cell viability using the PrestoBlue assay, analysis of cell membrane integrity using the lactate dehydrogenase assay, and reactive oxygen species production. Compared to Ag-NPs and GO, which have been widely used as antibacterial agents, our nanocomposite shows much higher antimicrobial efficiency toward bacteria and yeast cells.

Fe-Based Amorphous Coatings on AISI 4130 Structural Steel for Corrosion Resistance

NASA Astrophysics Data System (ADS)

Katakam, Shravana; Santhanakrishnan, S.; Dahotre, Narendra B.

2012-06-01

The current study focuses on synthesizing a novel functional coating for corrosion resistance applications, via laser surface alloying. The iron-based (Fe48Cr15Mo14Y2C15B) amorphous precursor powder is used for laser surface alloying on AISI 4130 steel substrate, with a continuous wave ytterbium Nd-YAG fiber laser. The corrosion resistance of the coatings is evaluated for different processing conditions. The microstructural evolution and the response of the microstructure to the corrosive environment is studied using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Microstructural studies indicate the presence of face-centered cubic Fe-based dendrites intermixed within an amorphous matrix along with fine crystalline precipitates. The corrosion resistance of the coatings decrease with an increase in laser energy density, which is attributed to the precipitation and growth of chromium carbide. The enhanced corrosion resistance of the coatings processed with low energy density is attributed to the self-healing mechanism of this amorphous system.

Characterization and tribology of PEG-like coatings on UHMWPE for total hip replacements.

PubMed

Kane, Sheryl R; Ashby, Paul D; Pruitt, Lisa A

2010-03-15

A crosslinked hydrogel coating similar to poly(ethylene glycol) (PEG) was covalently bonded to the surface of ultrahigh molecular weight polyethylene (UHMWPE) to improve the lubricity and wear resistance of the UHWMPE for use in total joint replacements. The chemistry, hydrophilicity, and protein adsorption resistance of the coatings were determined, and the wear behavior of the PEG-like coating was examined by two methods: pin-on-disk tribometry to evaluate macroscale behavior, and atomic force microscopy (AFM) to simulate asperity wear. As expected, the coating was found to be highly PEG-like, with approximately 83% ether content by x-ray photoelectron spectroscopy and more hydrophilic and resistant to protein adsorption than uncoated UHMWPE. Pin-on-disk testing showed that the PEG-like coating could survive 3 MPa of contact pressure, comparable to that experienced by total hip replacements. AFM nanoscratching experiments uncovered three damage mechanisms for the coatings: adhesion/microfracture, pure adhesion, and delamination. The latter two mechanisms appear to correlate well with wear patterns induced by pin-on-disk testing and evaluated by attenuated total reflection Fourier transform infrared spectroscopy mapping. Understanding the mechanisms by which the PEG-like coatings wear is critical for improving the behavior of subsequent generations of wear-resistant hydrogel coatings. (c) 2009 Wiley Periodicals, Inc.

High temperature oxidation resistance of magnetron-sputtered homogeneous CrAlON coatings on 430 steel

NASA Astrophysics Data System (ADS)

Garratt, E.; Wickey, K. J.; Nandasiri, M. I.; Moore, A.; AlFaify, S.; Gao, X.; Kayani, A.; Smith, R. J.; Buchanan, T. L.; Priyantha, W.; Kopczyk, M.; Gannon, P. E.

2009-11-01

The requirements of low cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigated the performance of steel plates with homogenous coatings of CrAlON (oxynitrides). The coatings were deposited using RF magnetron sputtering, with Ar as a sputtering gas. Oxygen in these coatings was not intentionally added. Oxygen might have come through contaminated nitrogen gas bottle, leak in the chamber or from the partial pressure of water vapors. Nitrogen was added during the growth process to get oxynitride coating. The Cr/Al composition ratio in the coatings was varied in a combinatorial approach. The coatings were subsequently annealed in air for up to 25 hours at 800 oC. The composition of the coated plates and the rate of oxidation were characterized using Rutherford backscattering (RBS) and nuclear reaction analysis (NRA). Surface characterization was carried out using Atomic Force Microscopy (AFM) and surfaces of the coatings were found smooth on submicron scale. From our results, we conclude that Al rich coatings are more susceptible to oxidation than Cr rich coatings.

Surface Enhancement For Optical Plastics

NASA Astrophysics Data System (ADS)

Masso, Jon D.

1988-07-01

Optical plastics can be molded or cast to replicate traditional spherical and aspheric lenses. It is possible to obtain good optical quality, but often it is necessary or desirable to enhance the surface characteristics in a variety of ways. These include improving the abrasion resistance, chemical resistance, the addition of anti-fog, or anti-static characteristics, applying electrically conductive coatings, and applying coatings or selective absorbers for light and color control. Coatings may be entirely organic or organo-silanes applied by dipping or spinning. All dielectric coatings such as quartz abrasion resistant coatings or multilayer dielectric coatings for reflection reduction or enhancement may be applied by vacuum vapor deposition. This paper discusses a number of these coatings and surface treatments. The paper describes their characteristics and includes discussions of their durability and environmental stability. The adhesion of coatings to plastic substrate depends on the specific substrate and coating materials. Pretreatments or primers are used to promote good coating adhesion. A coating used for one purpose will generally affect other properties of the plastic and trade-offs are sometimes required. A description is given of several test methods which have been found useful in evaluating the quality of the various coatings.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT--EVERMORE PAINTS AND COATINGS INC. FORMULA 5 COATING

EPA Science Inventory

This report is of a test of the pollution prevention capabilities of a polyamide-epoxy-silicone modified paint coating. It was analyzed for volatile organic emissions, hazardous air pollutants, film thickness, gloss, appearance, MEK rub resistance, abrasion resistance and other ...

Study on the corrosion properties of nanocrystalline nickel electrodepositied by reverse pulse current

NASA Astrophysics Data System (ADS)

Cheng, Wen; Ge, Wen; Yang, Qian; Qu, Xinxin

2013-07-01

Nanocrystalline nickel coatings were produced by the method of reverse pulse electrodepositing on the surface of steel sheets. The crystallite size of nanocrystalline nickel coatings was determined by X-ray diffraction (XRD). The effect of saccharin concentration on the crystallite size of the coatings was studied. The average crystallite sizes were diminished as a result of increasing saccharin concentration. CHI660C electrochemical workstation was used to determine the Tafel polarization curves and electrochemical impedance spectroscopy (EIS) of the coatings. The value of corrosion potential, natural corrosion current density, polarizaiton resistance and impedance was calculated, the results suggested that smaller grain size led to higher polarization resistance. EIS gave the charge transfer resistance Rct and pore resistance Rpo variation trend from beginning to 30 min. Scanning electron microscopy (SEM) examination showed the surface morphology of the nickel coatings after the neutral salt spray (NSS) test or bathing in 10% HCl. The images indicated that the corrosion behavior of nanocrystalline nickel coatings was pitting corrosion, the mechanism was also discussed.

Study of high resistance inorganic coatings on graphite fibers. [for graphite-epoxy composite materials

NASA Technical Reports Server (NTRS)

Galasso, F. S.; Veltri, R. D.; Scola, D. A.

1979-01-01

Coatings made of boron, silicon carbide, silica, and silica-like materials were studied to determine their ability to increase resistance of graphite fibers. The most promising results were attained by chemical vapor depositing silicon carbide on graphite fiber followed by oxidation, and drawing graphite fiber through ethyl silicate followed by appropriate heat treatments. In the silicon carbide coating studies, no degradation of the graphite fibers was observed and resistance values as high as three orders of magnitude higher than that of the uncoated fiber was attained. The strength of a composite fabricated from the coated fiber had a strength which compared favorably with those of composites prepared from uncoated fiber. For the silica-like coated fiber prepared by drawing the graphite fiber through an ethyl silicate solution followed by heating, coated fiber resistances about an order of magnitude greater than that of the uncoated fiber were attained. Composites prepared using these fibers had flexural strengths comparable with those prepared using uncoated fibers, but the shear strengths were lower.

Deposition of Coatings for Raising the Wear Resistance of Friction Surfaces of Spherical Sliding Bearings

NASA Astrophysics Data System (ADS)

Gorlenko, A. O.; Davydov, S. V.

2018-01-01

The process of finishing plasma hardening with deposition of a multilayer amorphous coating of the Si - O - C - N system is considered as applied to hardening of the friction surfaces of spherical sliding bearings. The microrelief, the submicrorelief, and the tribological characteristics of the deposited wear-resistant antifriction amorphous coating, which are responsible for the elevated wear resistance of spherical sliding bearings, are investigated.

Bottom Extreme-Ultraviolet-Sensitive Coating for Evaluation of the Absorption Coefficient of Ultrathin Film

NASA Astrophysics Data System (ADS)

Hijikata, Hayato; Kozawa, Takahiro; Tagawa, Seiichi; Takei, Satoshi

2009-06-01

A bottom extreme-ultraviolet-sensitive coating (BESC) for evaluation of the absorption coefficients of ultrathin films such as extreme ultraviolet (EUV) resists was developed. This coating consists of a polymer, crosslinker, acid generator, and acid-responsive chromic dye and is formed by a conventional spin-coating method. By heating the film after spin-coating, a crosslinking reaction is induced and the coating becomes insoluble. A typical resist solution can be spin-coated on a substrate covered with the coating film. The evaluation of the linear absorption coefficients of polymer films was demonstrated by measuring the EUV absorption of BESC substrates on which various polymers were spin-coated.

The effect of substrate bias voltages on impact resistance of CrAlN coatings deposited by modified ion beam enhanced magnetron sputtering

NASA Astrophysics Data System (ADS)

Chunyan, Yu; Linhai, Tian; Yinghui, Wei; Shebin, Wang; Tianbao, Li; Bingshe, Xu

2009-01-01

CrAlN coatings were deposited on silicon and AISI H13 steel substrates using a modified ion beam enhanced magnetron sputtering system. The effect of substrate negative bias voltages on the impact property of the CrAlN coatings was studied. The X-ray diffraction (XRD) data show that all CrAlN coatings were crystallized in the cubic NaCl B1 structure, with the (1 1 1), (2 0 0) (2 2 0) and (2 2 2) diffraction peaks observed. Two-dimensional surface morphologies of CrAlN coatings were investigated by atomic force microscope (AFM). The results show that with increasing substrate bias voltage the coatings became more compact and denser, and the microhardness and fracture toughness of the coatings increased correspondingly. In the dynamic impact resistance tests, the CrAlN coatings displayed better impact resistance with the increase of bias voltage, due to the reduced emergence and propagation of the cracks in coatings with a very dense structure and the increase of hardness and fracture toughness in coatings.

High temperature oxidation resistant coatings for the directionally solidified Ni-Nb-Cr-Al eutectic superalloy

NASA Technical Reports Server (NTRS)

Strangman, T. E.; Ulion, N. E.; Felten, E. J.

1977-01-01

Protective coatings required for the Ni-Nb-Cr-Al directionally solidified eutectic superalloy were developed and evaluated on the basis of oxidation resistance, diffusional stability, thermal fatigue, and creep resistance. NiCrAlY+Pt and NiCrAlY physical vapor-deposition coating systems exhibited the best combination of properties. Burner-rig testing indicated that the useful life of a 127-micron-thick NiCrAlY+Pt coating exceeds 1000 h at 1366 K. Eutectic-alloy creep lives at 1311 K and a stress of 151.7 MN/sq m were greater for NiCrAlY+Pt-coated specimens than for uncoated specimens by a factor of two.

Mechanism of Bacillus subtilis Spore Inactivation by and Resistance to Supercritical CO2 plus Peracetic Acid

PubMed Central

Setlow, Barbara; Korza, George; Blatt, Kelly M.S.; Fey, Julien P.; Setlow, Peter

2015-01-01

Aims Determine how supercritical CO2 (scCO2) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2-PAA, and if spores inactivated by scCO2-PAA are truly dead. Methods and Results Spores of wild-type B. subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2-PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2-PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2-PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2-PAA sensitive. Conclusions These findings suggest that scCO2-PAA inactivates spores by damaging spores’ inner membrane. The spore coat provided scCO2-PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2-PAA resistance only for dry spores. Significance and Impact of Study These results provide information on mechanisms of spore inactivation of and resistance to scCO2-PAA, an agent with increasing use in sterilization applications. PMID:26535794

Mechanism of Bacillus subtilis spore inactivation by and resistance to supercritical CO2 plus peracetic acid.

PubMed

Setlow, B; Korza, G; Blatt, K M S; Fey, J P; Setlow, P

2016-01-01

Determine how supercritical CO2 (scCO2 ) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2 -PAA, and if spores inactivated by scCO2 -PAA are truly dead. Spores of wild-type B. subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2 -PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2 -PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2 -PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2 -PAA sensitive. These findings suggest that scCO2 -PAA inactivates spores by damaging spores' inner membrane. The spore coat provided scCO2 -PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2 -PAA resistance only for dry spores. These results provide information on mechanisms of spore inactivation of and resistance to scCO2 -PAA, an agent with increasing use in sterilization applications. © 2015 The Society for Applied Microbiology.

A review of the use of wear-resistant coatings in the cutting-tool industry

NASA Technical Reports Server (NTRS)

Salik, J.

1983-01-01

The main mechanisms involved in the wear of cutting tools are reviewed. Evaluation of the different coating properties required for the reduction of the different kinds of wear was also reviewed. The types of coatings and their ranges of applicability are presented and discussed in view of their properties. Various coating processes as well as their advantages and shortcomings are described. Potential future developments in the field of wear-resistant coatings are discussed.

Corrosion resistant thermal barrier coating. [protecting gas turbines and other engine parts

NASA Technical Reports Server (NTRS)

Levine, S. R.; Miller, R. A.; Hodge, P. E. (Inventor)

1981-01-01

A thermal barrier coating system for protecting metal surfaces at high temperature in normally corrosive environments is described. The thermal barrier coating system includes a metal alloy bond coating, the alloy containing nickel, cobalt, iron, or a combination of these metals. The system further includes a corrosion resistant thermal barrier oxide coating containing at least one alkaline earth silicate. The preferred oxides are calcium silicate, barium silicate, magnesium silicate, or combinations of these silicates.

Microstructure and corrosive wear resistance of plasma sprayed Ni-based coatings after TIG remelting

NASA Astrophysics Data System (ADS)

Tianshun, Dong; Xiukai, Zhou; Guolu, Li; Li, Liu; Ran, Wang

2018-02-01

Ni based coatings were prepared on steel substrate by means of plasma spraying, and were remelted by TIG (tungsten inert gas arc) method subsequently. The microstructure, microhardness, electrochemical corrosion and corrosive wear resistance under PH = 4, PH = 7 and PH = 10 conditions of the coatings before and after remelting were investigated. The results showed that the TIG remelting obviously reduced the defects and dramatically decreased the coating’s porosity from 7.2% to 0.4%. Metallurgical bonding between the remelted coating and substrate was achieved. Meanwhile, the phase compositions of as-sprayed coating were γ-Ni, Mn5Si2 and Cr2B, while the phase compositions of the remelting coating were Fe3Ni, Cr23C6, Cr2B and Mn5Si2. The microhardness of the coating decreased from 724 HV to 608 HV, but the fracture toughness enhanced from 2.80 MPa m1/2 to 197.3 MPa m1/2 after remelting. After corrosive wear test, the average wear weight loss and 3D morphology of wear scar of two coatings indicated that the wear resistance of the remelted coating was remarkably higher than that of as-sprayed coating. Therefore, TIG remelting treatment was a feasible method to improve the coating’s microstructure and enhance its corrosive wear resistance.

Pulsed Laser Deposition Processing of Improved Titanium Nitride Coatings for Implant Applications

NASA Astrophysics Data System (ADS)

Haywood, Talisha M.

Recently surface coating technology has attracted considerable attention of researchers to develop novel coatings with enhanced functional properties such as hardness, biocompatibility, wear and corrosion resistance for medical devices and surgical tools. The materials currently being used for surgical implants include predominantly stainless steel (316L), cobalt chromium (Co-Cr), titanium and its alloys. Some of the limitations of these implants include improper mechanical properties, corrosion resistance, cytotoxicity and bonding with bone. One of the ways to improve the performance and biocompatibility of these implants is to coat their surfaces with biocompatible materials. Among the various coating materials, titanium nitride (TiN) shows excellent mechanical properties, corrosion resistance and low cytotoxicity. In the present work, a systematic study of pulsed laser ablation processing of TiN coatings was conducted. TiN thin film coatings were grown on commercially pure titanium (Ti) and stainless steel (316L) substrates at different substrate temperatures and different nitrogen partial pressures using the pulsed laser deposition (PLD) technique. Microstructural, surface, mechanical, chemical, corrosion and biological analysis techniques were applied to characterize the TiN thin film coatings. The PLD processed TiN thin film coatings showed improvements in mechanical strength, corrosion resistance and biocompatibility when compared to the bare substrates. The enhanced performance properties of the TiN thin film coatings were a result of the changing and varying of the deposition parameters.

a Study of Composite Coatings on 22MnCrNiMo Steel for Mooring Chain

NASA Astrophysics Data System (ADS)

Shen, Yan; Sahoo, Prasanta K.; Pan, Yipeng

In order to enhance the corrosion resistance of mooring chain, the composite coatings are carried out on the surface of 22MnCrNiMo steel for mooring chain by double-pulsed electrodeposition technology using centrifugal force in the rotating device. The microstructure and anti-corrosion performance of the composite coatings have been investigated experimentally. This paper mainly focuses on the experimental work to determine the structural characteristics and corrosion resistance of composite coatings in the presence of nano-SiC. The results show that the presence of nano-SiC has a significant effect on the preparation of composite coating during the process. The surface of the coating becomes compact and smooth at a moderate concentration of nano-SiC particles. Furthermore, the best corrosion resistance of the composite coatings can be obtained when the concentration of nano-SiC particles is 2.0g.L-1 after salt spray treatment.

Effects of weathering on performance of intumescent coatings for structure fire protection in the wildland-urban interface

NASA Astrophysics Data System (ADS)

Bahrani, Babak

The objective of this study was to investigate the effects of weathering on the performance of intumescent fire-retardant coatings on wooden products. The weathering effects included primary (solar irradiation, moisture, and temperature) and secondary (environmental contaminants) parameters at various time intervals. Wildland urban interface (WUI) fires have been an increasing threat to lives and properties. Existing solutions to mitigate the damages caused by WUI fires include protecting the structures from ignition and minimizing the fire spread from one structure to another. These solutions can be divided into two general categories: active fire protection systems and passive fire protection systems. Passive systems are either using pre-applied wetting agents (water, gel, or foam) or adding an extra layer (composite wraps or coatings). Fire-retardant coating treatment methods can be divided into impregnated (penetrant) and intumescent categories. Intumescent coatings are easy to apply, economical, and have a better appearance in comparison to other passive fire protection methods, and are the main focus of this study. There have been limited studies conducted on the application of intumescent coatings on wooden structures and their performance after long-term weathering exposure. The main concerns of weathering effects are: 1) the reduction of ignition resistance of the coating layer after weathering; and 2) the fire properties of coatings after weathering since coatings might contribute as a combustible fuel and assist the fire growth after ignition. Three intumescent coatings were selected and exposed to natural weathering conditions in three different time intervals. Two types of tests were performed on the specimens: a combustibility test consisted of a bench-scale performance evaluation using a Cone Calorimeter, and a thermal decomposition test using Simultaneous Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) method (also known as SDT). For each coating type and weathering period, three different radiative heat flux levels were used in the combustibility tests. Data obtained from the tests, including flammability and thermal properties, were gathered, analyzed, and compared to non-weathered specimens. The results revealed visible effects of weathering on pre (and up to)-ignition flammability and intumescent properties, especially decreases in Time-to-Ignition (TTI), Time-to-Intumescence (tintu.), and (maximum) Intumescence Height (Hintu.) values in weathered specimens. These results showed that the ignition resistance of the coating layers decreased after weathering exposure. On the other hand, the obtained results from weathered specimens for the post-ignition flammability properties, especially Peak Heat Release Rate (PHRR) and Effective Heat of Combustion (EHC) did not show a significant difference in comparison to the non-weathered samples. These results demonstrated that the weathered coating layer would not likely to act as an additional combustible fuel to increase fire spread.

Features of Wear-Resistant Cast Iron Coating Formation During Plasma-Powder Surfacing

NASA Astrophysics Data System (ADS)

Vdovin, K. N.; Emelyushin, A. N.; Nefed'ev, S. P.

2017-09-01

The structure of coatings deposited on steel 45 by plasma-powder surfacing of white wear-resistant cast iron is studied. The effects of surfacing regime and additional production effects on the welding bath during surfacing produced by current modulation, accelerated cooling of the deposited beads by blowing with air, and accelerated cooling of the substrate with running water on the structure, are determined. A new composition is suggested for powder material for depositing wear-resistant and corrosion-resistant coatings on a carbon steel by the plasma-powder process.

Influence of Halide Solutions on Collagen Networks: Measurements of Physical Properties by Atomic Force Microscopy

PubMed Central

Kempe, André; Lackner, Maximilian

2016-01-01

The influence of aqueous halide solutions on collagen coatings was tested. The effects on resistance against indentation/penetration on adhesion forces were measured by atomic force microscopy (AFM) and the change of Young's modulus of the coating was derived. Comparative measurements over time were conducted with halide solutions of various concentrations. Physical properties of the mesh-like coating generally showed large variability. Starting with a compact set of physical properties, data disperse after minutes. A trend of increase in elasticity and permeability was found for all halide solutions. These changes were largest in NaI, displaying a logical trend with ion size. However a correlation with concentration was not measured. Adhesion properties were found to be independent of mechanical properties. The paper also presents practical experience for AFM measurements of soft tissue under liquids, particularly related to data evaluation. The weakening in physical strength found after exposure to halide solutions may be interpreted as widening of the network structure or change in the chemical properties in part of the collagen fibres (swelling). In order to design customized surface coatings at optimized conditions also for medical applications, halide solutions might be used as agents with little impact on the safety of patients. PMID:27721994

Fabrication of Oxide Dispersion Strengthened Bond Coats with Low Al2O3 Content

NASA Astrophysics Data System (ADS)

Bergholz, Jan; Pint, Bruce A.; Unocic, Kinga A.; Vaßen, Robert

2017-06-01

Nanoscale oxide dispersions have long been used to increase the oxidation and wear resistance of alloys used as bond coatings in thermal barrier coatings. Their manufacturing via mechanical alloying is often accompanied by difficulties regarding their particle size, homogeneous distribution of the oxide dispersions inside the powder, involving considerable costs, due to cold welding of the powder during milling. A significant improvement in this process can be achieved by the use of process control agent (PCA) to achieve the critical balance between cold welding and fracturing, thereby enhancing the process efficiency. In this investigation, the influence of the organic additive stearic acid on the manufacturing process of Al2O3-doped CoNiCrAlY powder was investigated. Powders were fabricated via mechanical alloying at different milling times and PCA concentrations. The results showed a decrease in particle size, without hindering the homogeneous incorporation of the oxide dispersions. Two powders manufactured with 0.5 and 1.0 wt.% PCA were deposited by high velocity oxygen fuel (HVOF) spraying. Results showed that a higher content of elongated particles in the powder with the higher PCA content led to increased surface roughness, porosity and decreased coating thickness, with areas without embedded oxide particles.

Bioactive Ca-P coating with self-sealing structure on pure magnesium.

PubMed

Gan, Junjie; Tan, Lili; Yang, Ke; Hu, Zhuangqi; Zhang, Qiang; Fan, Xinmin; Li, Yangde; Li, Weirong

2013-04-01

Bioactive coatings containing Ca and P with self-sealing structures were fabricated on the surface of pure magnesium using micro-arc oxidation technique (MAO) in a specific calcium hydroxide based electrolyte system. Coatings were prepared at three applied voltages, i.e. 360, 410 and 450 V, and the morphology, chemical composition, corrosion resistance and the degradation properties in Hank's solution of the MAO-coated samples with three different applied voltages were investigated. It was found that all the three coatings showed similar surface morphologies that the majority of micro-pores were filled with compound particles. Both the porous structures and the compound particles were found to contain consistent chemical compositions which were mainly composed of O, Mg, F, Ca and P. Electrochemical tests showed a significant increase in corrosion resistance for the three coatings, meanwhile the coating obtained at 450 V exhibited the superior corrosion resistance owing to the largest coating thickness. The long term immersion tests in Hank's solution also revealed an effective reduction in corrosion rate for the MAO coated samples, and the pH values of the coated samples always maintained a lower level. Besides, all the three coatings were subjected to a mild and uniform degradation, while the coating obtained at 360 V showed a relatively obvious degradation characteristic and appreciable Ca and P contents on the surfaces of the three coatings were observed after immersion in Hank's solution. The results of the present study confirmed that the MAO coatings containing bioactive Ca and P elements with self-sealing structures could significantly enhance the corrosion resistance of magnesium substrate in Hanks' solution with great potential for medical application.

Substrate-independent superliquiphobic coatings for water, oil, and surfactant repellency: An overview.

PubMed

Bhushan, Bharat; Martin, Samuel

2018-09-15

Superliquiphobic surfaces that exhibit self-cleaning, antifouling, finger touch resistance, and low drag properties with high transparency are of interest in industrial applications including optical devices, solar panels, and self-cleaning windows. In this paper, an overview of coatings using a simple and scalable fabrication technique are presented that exhibit superoleophobic/philic properties, wear resistance, finger touch resistance, and transparency. The coating comprises hydrophobic SiO 2 nanoparticles with a binder of methylphenyl silicone resin. After ultraviolet-ozone treatment to the coating, an additional coating of fluorosilane or fluorosurfactant modifies the coated surface for superoleophobicity or superoleophilicity, respectively. Data for these coatings are presented showing substrate independency, the ability to repel surfactant-containing liquids such as shampoo and laundry detergent, oil-water separation, and the ability to survive up to 80 °C environments. The coatings were designed to have re-entrant geometry desirable for superoleophobicity with liquids with very low surface tension as well as surfactants. Copyright © 2018 Elsevier Inc. All rights reserved.

Synthesis and characterization of in situ TiC-TiB2 composite coatings by reactive plasma spraying on a magnesium alloy

NASA Astrophysics Data System (ADS)

Zou, Binglin; Tao, Shunyan; Huang, Wenzhi; Khan, Zuhair S.; Fan, Xizhi; Gu, Lijian; Wang, Ying; Xu, Jiaying; Cai, Xiaolong; Ma, Hongmei; Cao, Xueqiang

2013-01-01

TiC-TiB2 composite coatings were successfully synthesized using the technique of reactive plasma spraying (RPS) on a magnesium alloy. Phase composition, microstructure and wear resistance of the coatings were characterized by using X-ray diffraction, scanning electron microscopy and pin-on-disk wear test, respectively. The results showed that the resultant product in the RPS coatings was composed of TiC and TiB2. Depending on the ignition of self-propagating high-temperature synthesis reaction in the agglomerate particles, the RPS coatings displayed porous and dense microstructures. The porosity of the RPS coatings, to some extent, decreased when the feed powders were plasma sprayed with Ni powders. The RPS coatings provided good wear resistance for the substrate under various loads. For high loads (e.g., ≥15 N), the wear resistance could be significantly improved by the proper addition of Ni into the RPS coatings.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukhametkaliyev, T., E-mail: mtm91@mail.ru; Surmeneva, M., E-mail: feja-mari@yandex.ru; Surmenev, R., E-mail: rsurmenev@gmail.com

A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradationmore » resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density I{sub corr} reduced by ∼ 98% as compared to the base alloy.« less

An investigation of enhanced capability thermal barrier coating systems for diesel engine components

NASA Technical Reports Server (NTRS)

Holtzman, R. L.; Layne, J. L.; Schechter, B.

1984-01-01

Material systems and processes for the development of effective and durable thermal barriers for heavy duty diesel engines were investigated. Seven coating systems were evaluated for thermal conductivity, erosion resistance, corrosion/oxidation resistance, and thermal shock resistance. An advanced coating system based on plasma sprayed particle yttria stabilized zirconia (PS/HYSZ) was judged superior in these tests. The measured thermal conductivity of the selected coating was 0.893 W/m C at 371 C. The PS/HYSZ coating system was applied to the piston crown, fire deck and valves of a single cylinder low heat rejection diesel engine. The coated engine components were tested for 24 hr at power levels from 0.83 MPa to 1.17 MPa brake mean effective pressure. The component coatings survived the engine tests with a minimum of distress. The measured fire deck temperatures decreased 86 C (155 F) on the intake side and 42 C (75 F) on the exhaust side with the coating applied.

Characterization of corrosion resistant on NiCoCr coating layer exposed to 5%NaCl

NASA Astrophysics Data System (ADS)

Sugiarti, E.; Sundawa, R.; Desiati, R. D.; Zaini, K. A.

2018-03-01

Highly corrosion resistant of carbon steel coated NiCoCr was applied in corrosive of marine environtment. Carbon steel coated NiCoCr was prepared by a two step technique of NiCo electro-deposition and Cr pack cementation. The samples were exposed to 5 wt.% NaCl for 48 and 168 hours. The microstructure and corrosion product were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The corrosion resistance of carbon steel coated NiCoCr was found to be better than that of carbon steel substrate without coating. The results showed the microstructure of 48 h corroded sample has duplex layer composed of inner α-(Ni,Co), α-Cr and outer Cr2O3, while a quite thin and continues protective oxide of Cr2O3 was observed in outer layer of 168 h corroded sample. The formation of oxide scale rich in Cr2O3 has contributed for the better corrosion resistance of carbon steel coated NiCoCr, whereas the formation of non protective oxide of iron might caused low corrosion resistance of carbon steel substrate.

High Corrosion Resistance Offered by Multi-Walled Carbon Nanotubes Directly Grown Over Mild Steel Substrate

NASA Astrophysics Data System (ADS)

Arora, Sweety; Rekha, M. Y.; Gupta, Abhay; Srivastava, Chandan

2018-02-01

The inert and hydrophobic nature of carbon nanotubes (CNTs) makes them a potential material for corrosion protection coatings. In this work, a uniform coating of multi-walled CNTs (MWCNTs) was formed over a mild steel substrate by direct decomposition of a ferrocene-benzene mixture over the substrate which was kept inside a chemical vapor deposition setup at a temperature of 800°C. The MWCNTs formed over the substrate were characterized using x-ray diffraction, Raman spectroscopy and transmission electron microscopy techniques. Corrosion behavior of the bare and MWCNT-coated mild steel substrate was examined through potentiodynamic polarization and electrochemical impedance spectroscopy methods. A significant improvement in the corrosion resistance in terms of the reduction in corrosion current and corrosion rate and increase in polarization resistance was noted in the case of the MWCNT-coated mild steel plate. Corrosion resistance increased due to MWCNT coating.

Investigation on wear resistance and corrosion resistance of electron beam cladding co-alloy coating on Inconel617

NASA Astrophysics Data System (ADS)

Liu, Hailang; Zhang, Guopei; Huang, Yiping; Qi, Zhengwei; Wang, Bo; Yu, Zhibiao; Wang, Dezhi

2018-04-01

To improve surface properties of Inconel 617 alloy (referred to as 617 alloy), co-alloy coating metallurgically bonded to substrate was prepared on the surface of 617 alloy by electron beam cladding. The microstructure, phase composition, microhardness, tribological properties and corrosion resistance of the coatings were investigated. The XRD results of the coatings reinforced by co-alloy (Co800) revealed the presence of γ-Co, CoCx and Cr23C6 phase as matrix and new metastable phases of Cr2Ni3 and Co3Mo2Si. These hypoeutectic structures contain primary dendrites and interdendritic eutectics. The metallurgical bonding forms well between the cladding layer and the matrix of 617 alloy. In most studied conditions, the co-alloy coating displays a better hardness, tribological performance, i.e., lower coefficient of frictions and wear rates, corrosion resistance in 1 mol L‑1 HCl solution, than the 617 alloy.

Microchannel plate detector and methods for their fabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elam, Jeffrey W.; Mane, Anil U.; Peng, Qing

A multi-component tunable resistive coating and methods of depositing the coating on the surfaces of a microchannel plate (MCP) detector. The resistive coating composed of a plurality of alternating layers of a metal oxide resistive component layer and a conductive component layer composed of at least one of a metal, a metal nitride and a metal sulfide. The coating may further include an emissive layer configured to produce a secondary electron emission in response to a particle interacting with the MCP and a neutron-absorbing layer configured to respond to a neutron interacting with the MCP.

Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions (Invited paper)

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2008-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2008-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires.

PubMed

da Silva, Dayanne Lopes; Santos, Emanuel; Camargo, Sérgio de Souza; Ruellas, Antônio Carlos de Oliveira

2015-09-01

To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires. The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test. The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm(-1). The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches. The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.

Effects of hydroxyapatite/Zr and bioglass/Zr coatings on morphology and corrosion behaviour of Rex-734 alloy.

PubMed

Say, Y; Aksakal, B

2016-06-01

To improve corrosion resistance of metallic implant surfaces, Rex-734 alloy was coated with two different bio-ceramics; single-Hydroxyapatite (HA), double-HA/Zirconia(Zr) and double-Bioglass (BG)/Zr by using sol-gel method. Porous surface morphologies at low crack density were obtained after coating and sintering processes. Corrosion characteristics of coatings were determined by Open circuit potential and Potentiodynamic polarization measurements during corrosion tests. Hardness and adhesion strength of coating layers were measured and their surface morphologies before and after corrosion were characterized by scanning electron microscope (SEM), XRD and EDX. Through the SEM analysis, it was observed that corrosion caused degradation and sphere-like formations appeared with dimples on the coated surfaces. The coated substrates that exhibit high crack density, the corrosion was more effective by disturbing and transmitting through the coating layer, produced CrO3 and Cr3O8 oxide formation. It was found that the addition of Zr provided an increase in adhesion strength and corrosion resistance of the coatings. However, BG/Zr coatings had lower adhesion strength than the HA/Zr coatings, but showed higher corrosion resistance.

Procedure for contact electrical resistance measurements as developed for use at Sandia National Laboratories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finch, J.L.

1994-06-01

Military Specifications call out general procedures and guidelines for conducting contact resistance measurements on chemical conversion coated panels. This paper deals with a test procedure developed at Sandia National Laboratories used to conduct contact electrical resistance on non-chromated conversion coated test panels. MIL-C-81706 {open_quotes}Chemical Conversion Materials For Coating Aluminum and Aluminum Alloys{close_quotes} was the reference specification used for guidance.

[Endoscopic diagnosis of local chemical burn of mucous membranes of the stomach, induced with the purpose of simulation of gastric ulcer].

PubMed

Byzov, N V; Plekhanov, V N

2013-01-01

With the purpose of improvement of diagnosis of induced gastric ulcer were examined 11 patients who took aggressive agents for simulation of gastric ulcer and 33 patients who took pseudo-aggressive agents. Observables, conduced diagnosis of local chemical burn of mucous coat of stomach during initial 6 days after taking aggressive agents. Stages of ulcerous process, resulting from local chemical burn of mucous coat of stomach, coressponds to real gactric ulcer. Gelatin capsule using as a container for delivery of aggressive agents, melts in stomach in 5-6 minutes after taking. Independent from body position, mucous coat of greater curvature of the stomach is damaged. It is impossible to simulate duodenal bulb ulcer using the gelatine capsule or ball made of breadcrumb. The last method of delivery of aggressive agent can damage the small intestine because of uncontrollability of the place of breaking the ball.

Moisture Resistant Finishes for Airplane Woods

NASA Technical Reports Server (NTRS)

Dunlap, M E

1921-01-01

This report describes briefly a series of experiments made at the Forest Products Laboratory, Madison, Wisconsin, to determine the comparative moisture resistance of linseed oil, impregnation treatments, condensation varnishes, oil varnishes, enamels, cellulose varnishes, rubber, electroplated and sprayed metal coatings, and metal-leaf coatings when applied to wood. All coatings except rubber and electroplated metal coatings, which were not developed sufficiently to make them practical, admitted moisture in varying degrees. The most effective and most practical coating was found to be that of aluminum leaf.

The effect of Al intermediate layer on thermal resistance of EB-PVD yttria-stabilized zirconia coatings on titanium substrate

NASA Astrophysics Data System (ADS)

Panin, Alexey; Panin, Victor; Kazachenok, Marina; Shugurov, Artur; Sinyakova, Elena; Martynov, Sergey; Rusyaev, Andrey; Kasterov, Artur

2017-12-01

The yttria-stabilized zirconia coatings sprayed on titanium substrates by the electron beam physical vapor deposition were subjected to thermal annealing in air at 1000°C for 1, 30 and 60 min. The delamination and fracture of the coatings are studied by the scanning electron microscopy and X-ray diffraction. It is shown that a magnetron sputtered Al interlayer between the coating and the substrate considerably improves the thermal resistance of ceramic coatings.

Materials Coating Techniques

DTIC Science & Technology

1980-03-01

applications from decorative to utilitarian over significant segments of the engineering, chemical, nuclear , microelectronics, and related Industries. PVD...Thermal-control coating. Boron 2430 Cermet component, nuclear shielding and controlrod material; Carbide wear- and temperature-resistant. Calcium...Zirconium Oxide (Hafnia-Pree � Thermal-barrier coatings for nuclear applications. Lime Stabi!Aed) Zirconium 2563 Resistant to high-temperature

Duplex aluminized coatings

NASA Technical Reports Server (NTRS)

Gedwill, M. A.; Grisaffe, S. J. (Inventor)

1975-01-01

The surface of a metallic base system is initially coated with a metallic alloy layer that is ductile and oxidation resistant. An aluminide coating is then applied to the metallic alloy layer. The chemistry of the metallic alloy layer is such that the oxidation resistance of the subsequently aluminized outermost layer is not seriously degraded.

A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology.

PubMed

Song, Se Yeon; Park, Min Soo; Lee, Jung Woo; Yun, Ji Sun

2018-02-07

Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al₂O₃ ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al₂O₃ ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al₂O₃ ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al₂O₃/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter.

A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology

PubMed Central

Song, Se Yeon; Park, Min Soo; Lee, Jung Woo; Yun, Ji Sun

2018-01-01

Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al2O3 ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al2O3 ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al2O3 ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al2O3/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter. PMID:29414912

Impact of anti-tacking agents on properties of gas-entrapped membrane and effervescent floating tablets.

PubMed

Kriangkrai, Worawut; Puttipipatkhachorn, Satit; Sriamornsak, Pornsak; Pongjanyakul, Thaned; Sungthongjeen, Srisagul

2014-12-01

Tackiness caused by the gas-entrapped membrane (Eudragit(®)RL 30D) was usually observed during storage of the effervescent floating tablets, leading to failure in floatation and sustained release. In this work, common anti-tacking agents (glyceryl monostearate (GMS) and talc) were used to solve this tackiness problem. The impact of anti-tacking agent on the properties of free films and corresponding floating tablets was investigated. GMS was more effective than talc in reducing tackiness of the film. Addition and increasing amount of anti-tacking agents lowered the film mechanical strength, but the coating films were still strong and flexible enough to resist the generated gas pressure inside the floating tablet. Wettability and water vapor permeability of the film decreased with increasing level of anti-tacking agents as a result of their hydrophobicity. No interaction between anti-tacking agents and polymer was observed as confirmed by Fourier transform infrared spectroscopy, powder X-ray diffractometry, and differential scanning calorimetry studies. Increasing amount of anti-tacking agents decreased time to float and tended to retard drug release of the floating tablets. Floating properties and drug release were also influenced by type of anti-tacking agents. The obtained floating tablets still possessed good floating properties and controlled drug release even though anti-tacking agent had some effects. The results demonstrated that the tackiness problem of the floating tablets could be solved by incorporating anti-tacking agent into the gas-entrapped membrane.

Electrostatic coating technologies for food processing.

PubMed

Barringer, Sheryl A; Sumonsiri, Nutsuda

2015-01-01

The application of electrostatics in both powder and liquid coating can improve the quality of food, such as its appearance, aroma, taste, and shelf life. Coatings can be found most commonly in the snack food industry, as well as in confectionery, bakery, meat and cheese processing. In electrostatic powder coating, the most important factors influencing coating quality are powder particle size, density, flowability, charge, and resistivity, as well as the surface properties and characteristics of the target. The most important factors during electrostatic liquid coating, also known as electrohydrodynamic coating, include applied voltage and electrical resistivity and viscosity of the liquid. A good understanding of these factors is needed for the design of optimal coating systems for food processing.

Investigation of metallurgical coatings for automotive applications

NASA Astrophysics Data System (ADS)

Su, Jun Feng

Metallurgical coatings have been widely used in the automotive industry from component machining, engine daily running to body decoration due to their high hardness, wear resistance, corrosion resistance and low friction coefficient. With high demands in energy saving, weight reduction and limiting environmental impact, the use of new materials such as light Aluminum/magnesium alloys with high strength-weight ratio for engine block and advanced high-strength steel (AHSS) with better performance in crash energy management for die stamping, are increasing. However, challenges are emerging when these new materials are applied such as the wear of the relative soft light alloys and machining tools for hard AHSS. The protective metallurgical coatings are the best option to profit from these new materials' advantages without altering largely in mass production equipments, machinery, tools and human labor. In this dissertation, a plasma electrolytic oxidation (PEO) coating processing on aluminum alloys was introduced in engine cylinder bores to resist wear and corrosion. The tribological behavior of the PEO coatings under boundary and starve lubrication conditions was studied experimentally and numerically for the first time. Experimental results of the PEO coating demonstrated prominent wear resistance and low friction, taking into account the extreme working conditions. The numerical elastohydrodynamic lubrication (EHL) and asperity contact based tribological study also showed a promising approach on designing low friction and high wear resistant PEO coatings. Other than the fabrication of the new coatings, a novel coating evaluation methodology, namely, inclined impact sliding tester was presented in the second part of this dissertation. This methodology has been developed and applied in testing and analyzing physical vapor deposition (PVD)/ chemical vapor deposition (CVD)/PEO coatings. Failure mechanisms of these common metallurgical hard coatings were systematically studied and summarized via the new testing methodology. Field tests based on the new coating characterization technique proved that this methodology is reliable, effective and economical.

Microstructure and wear resistance of laser cladded composite coatings prepared from pre-alloyed WC-NiCrMo powder with different laser spots

NASA Astrophysics Data System (ADS)

Yao, Jianhua; Zhang, Jie; Wu, Guolong; Wang, Liang; Zhang, Qunli; Liu, Rong

2018-05-01

The distribution of WC particles in laser cladded composite coatings can significantly affect the wear resistance of the coatings under aggressive environments. In this study, pre-alloyed WC-NiCrMo powder is deposited on SS316L via laser cladding with circular spot and wide-band spot, respectively. The microstructure and WC distribution of the coatings are investigated with optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The wear behavior of the coatings is investigated under dry sliding-wear test. The experimental results show that the partially dissolved WC particles are uniformly distributed in both coatings produced with circular spot and wide-band spot, respectively, and the microstructures consist of WC and M23C6 carbides and γ-(Ni, Fe) solid solution matrix. However, due to Fe dilution, the two coatings have different microstructural characteristics, resulting in different hardness and wear resistance. The wide-band spot laser prepared coating shows better performance than the circular spot laser prepared coating.

Evaluation of resistant starch, glycemic index and fortificants content of premix rice coated with various concentrations and types of edible coating materials

NASA Astrophysics Data System (ADS)

Yulianto, W. A.; Susiati, A. M.; Adhini, H. A. N.

2018-01-01

The incidence of diabetes in Indonesia has been increasing year by year. Diets with a low glycemic index and high resistant starch foods can assist diabetics in controlling their blood glucose levels. Diabetics are known to have micro-nutrient deficiencies of chromium, magnesium and vitamin D that can be overcome by consuming parboiled rice fortified by use of a coating method. The fortification of parboiled rice (premix rice) can be achieved by coating with HPMC (hydroxypropyl methyl cellulose), MC (methyl cellulose), CMC (carboxyl methyl cellulose), gum arabic and rice starch. This research aimed to evaluate the levels of resistant starch, glycemic index and fortificants of premix rice coated with different concentrations and types of edible coating materials. This research used completely randomized design, with treatments to the concentrations and the types of edible coating (HPMC, CMC, MC, gum arabic and rice starch). The concentrations of edible coating were 0.15%, 0.2% and 0.25% for cellulose derivative coatings; 25%, 30%, 35% for gum arabic and 2%, 3.5% and 5% for rice starch. This research shows that fortified premix rice coated with various concentrations and types of edible coating materials is high in resistant starch and has a low glycemic index. The coating treatment affects the levels of magnesium and vitamin D, but does not affect the levels of chromium in parboiled rice. The premix rice with a low glycemic index and high nutrient content (chromium, magnesium and vitamin D) was premix rice coated by CMC 0.25% and HPMC 0.25% with glycemic indeces of 39.34 and 38.50, respectively.

Corrosion resistant coatings suitable for elevated temperature application

DOEpatents

Chan, Kwai S [San Antonio, TX; Cheruvu, Narayana Sastry [San Antonio, TX; Liang, Wuwei [Austin, TX

2012-07-31

The present invention relates to corrosion resistance coatings suitable for elevated temperature applications, which employ compositions of iron (Fe), chromium (Cr), nickel (Ni) and/or aluminum (Al). The compositions may be configured to regulate the diffusion of metals between a coating and a substrate, which may then influence coating performance, via the formation of an inter-diffusion barrier layer. The inter-diffusion barrier layer may comprise a face-centered cubic phase.

Thermal barrier coating life prediction model development

NASA Technical Reports Server (NTRS)

Strangman, T. E.; Neumann, J. F.; Tasooji, A.

1985-01-01

This program focuses on predicting the lives of two types of strain-tolerant and oxidation-resistant thermal barrier coating (TBC) systems that are produced by commercial coating suppliers to the gas turbine industry. The plasma-sprayed TBC system is composed of a low pressure, plasma sprayed applied, oxidation resistant NiCrAlY bond coating. The other system is an air plasma sprayed yttria (8 percent) partially stabilized zirconia insulative layer.

Next-generation all-silica coatings for UV applications

NASA Astrophysics Data System (ADS)

Melninkaitis, A.; Grinevičiūtė, L.; Abromavičius, G.; Mažulė, L.; Smalakys, L.; Pupka, E.; Š čiuka, M.; Buzelis, R.; Kičas, S.

2017-11-01

Band-gap and refractive index are known as fundamental properties determining intrinsic optical resistance of multilayer dielectric coatings. By considering this fact we propose novel approach to manufacturing of interference thin films, based on artificial nano-structures of modulated porosity embedded in high band-gap matrix. Next generation all-silica mirrors were prepared by GLancing Angle Deposition (GLAD) using electron beam evaporation. High reflectivity (HR) was achieved by tailoring the porosity of highly resistant silica material during the thin film deposition process. Furthermore, the proposed approach was also demonstrated to work well in case of anti-reflection (AR) coatings. Conventional HR HfO2 and SiO2 as well as AR Al2O3 and SiO2 multilayers produced by Ion Beam Sputtering (IBS) were used as reference coatings. Damage performance of experimental coatings was also analyzed. All-silica based GLAD approach resulted in significant improvement of intrinsic laser damage resistance properties if compared to conventional coatings. Besides laser damage testing, other characteristics of experimental coatings are analyzed and discussed - reflectance, surface roughness and optical scattering. We believe that reported concept can be expanded to virtually any design of thin film coatings thus opening a new way of next generation highly resistant thin films well suited for high power and UV laser applications.

Electrochemical Corrosion and In Vitro Bioactivity of SiO2:ZrO2-Coated 316L Stainless Steel in Simulated Body Fluid

NASA Astrophysics Data System (ADS)

Srinivasan, A.; Rajendran, N.

2015-08-01

The effect of Si:Zr ratio on the in vitro bioactivity and electrochemical corrosion behavior of SiO2:ZrO2-mixed oxide-coated 316L stainless steel (SS) was evaluated in simulated body fluid (SBF) solution for 72, 120, and 168 h. Growth of Hydroxyapatite (HAp) was accelerated when Si content in the coating was increased. The Zr content in the coating improved the corrosion resistance of 316L SS rather than accelerating the HAp growth. When the Si:Zr ratio was 50:50, the coating exhibited significant improvement in corrosion resistance as well as HAp growth. The mechanism of HAp growth was proposed based on the change in surface zeta potential values of the coatings. Potentiodynamic polarization studies revealed about 10 and 5 times reduction in corrosion current density ( i corr) values for SiO2:ZrO2 (50:50)-coated 316L SS after 168 h of immersion compared to SiO2, ZrO2, and Si:Zr (70:30) coatings in SBF solutions thus confirming the superior corrosion resistance. The equivalent circuit parameters derived from electrochemical impedance spectroscopy studies further confirmed significant improvement in charge transfer resistance value even after 168 h of exposure.

Interface characterization of Cu-Mo coating deposited on Ti-Al alloys by arc spraying

NASA Astrophysics Data System (ADS)

Bai, Shengqiang; Li, Fei; Wu, Ting; Yin, Xianglin; Shi, Xun; Chen, Lidong

2015-03-01

Cu-Mo pseudobinary alloys are promising candidates as electrode materials in CoSb3-based skutterudite thermoelectric (TE) devices for TE power generation. In this study, Cu-Mo coatings were deposited onto Ti-Al substrates by applying a dual-wire electric arc spraying coating technique. The microstructure of the surfaces, cross sections and coating interfaces were analyzed by scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS). Cu-Mo coatings showed a typical banded splat with compact microstructures, and have no coarse pores nor micro-cracks. The thermal shock resistance of the Cu-Mo coating was also investigated to show good combinations with Ti-Al substrates. After 50 thermal shock cycles, there were no cracks observed at the interface. In contrast, the test of the thermal shock resistance of the Cu coating on the Ti-Al substrate was also investigated. Due to a large difference in the thermal expansion coefficients between Cu and Ti-Al alloys, the Cu coating flaked from the Ti-Al substrate completely after 10 thermal shock cycles. The contact resistivity of the Ti-Al/Cu-Mo interface was about 1.6 μΩṡcm2 and this value was unchanged after 50 thermal shock cycles, indicating the low electric resistance and high thermal stability of the Cu-Mo/Ti-Al interface.

[Study on discrimination of varieties of fire resistive coating for steel structure based on near-infrared spectroscopy].

PubMed

Xue, Gang; Song, Wen-qi; Li, Shu-chao

2015-01-01

In order to achieve the rapid identification of fire resistive coating for steel structure of different brands in circulating, a new method for the fast discrimination of varieties of fire resistive coating for steel structure by means of near infrared spectroscopy was proposed. The raster scanning near infrared spectroscopy instrument and near infrared diffuse reflectance spectroscopy were applied to collect the spectral curve of different brands of fire resistive coating for steel structure and the spectral data were preprocessed with standard normal variate transformation(standard normal variate transformation, SNV) and Norris second derivative. The principal component analysis (principal component analysis, PCA)was used to near infrared spectra for cluster analysis. The analysis results showed that the cumulate reliabilities of PC1 to PC5 were 99. 791%. The 3-dimentional plot was drawn with the scores of PC1, PC2 and PC3 X 10, which appeared to provide the best clustering of the varieties of fire resistive coating for steel structure. A total of 150 fire resistive coating samples were divided into calibration set and validation set randomly, the calibration set had 125 samples with 25 samples of each variety, and the validation set had 25 samples with 5 samples of each variety. According to the principal component scores of unknown samples, Mahalanobis distance values between each variety and unknown samples were calculated to realize the discrimination of different varieties. The qualitative analysis model for external verification of unknown samples is a 10% recognition ration. The results demonstrated that this identification method can be used as a rapid, accurate method to identify the classification of fire resistive coating for steel structure and provide technical reference for market regulation.

The Effect of Boronizing on Metallic Alloys for Automotive Applications

NASA Astrophysics Data System (ADS)

Petrova, Roumiana S.; Suwattananont, Naruemon; Samardzic, Veljko

2008-06-01

In this study the wear resistance, corrosion resistance, and oxidation resistance of boronized metallic alloys were investigated. Thermochemical treatment was performed by powder pack boronizing process at temperature 850-950 °C for 4 h. Saw-tooth morphology and smooth interface microstructures were observed with an optical microscope; microhardness was measured across the coating depth. The phases present in the boron coatings depend on the substrate material. High-temperature oxidation resistance was investigated and it was found that boron coating on ferrous alloys can resist temperatures up to 800 °C. The corrosion resistance of the boronized samples was improved and the corrosion rate was calculated for boronized and plain specimens. Wear testing was conducted by following the procedures of ASTM G99, ASTM D2526, and ASTM D4060. The obtained experimental results revealed that boronizing significantly improves the wear-resistance, corrosion-resistance, and oxidation resistance of metallic alloys.

Ceramic Coatings for Corrosion Resistant Nuclear Waste Container Evaluated in Simulated Ground Water at 90?C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haslam, J J; Farmer, J C

2004-03-31

Ceramic materials have been considered as corrosion resistant coatings for nuclear waste containers. Their suitability can be derived from the fully oxidized state for selected metal oxides. Several types of ceramic coatings applied to plain carbon steel substrates by thermal spray techniques have been exposed to 90 C simulated ground water for nearly 6 years. In some cases no apparent macroscopic damage such as coating spallation was observed in coatings. Thermal spray processes examined in this work included plasma spray, High Velocity Oxy Fuel (HVOF), and Detonation Gun. Some thermal spray coatings have demonstrated superior corrosion protection for the plainmore » carbon steel substrate. In particular the HVOF and Detonation Gun thermal spray processes produced coatings with low connected porosity, which limited the growth rate of corrosion products. It was also demonstrated that these coatings resisted spallation of the coating even when an intentional flaw (which allowed for corrosion of the carbon steel substrate underneath the ceramic coating) was placed in the coating. A model for prediction of the corrosion protection provided by ceramic coatings is presented. The model includes the effect of the morphology and amount of the porosity within the thermal spray coating and provides a prediction of the exposure time needed to produce a crack in the ceramic coating.« less

The Oxidation and Protection of Gamma Titanium Aluminides

NASA Technical Reports Server (NTRS)

Brady, Michael P.; Brindley, William J.; Smialek, James L.; Locci, Ivan E.

1996-01-01

The excellent density-specific properties of the gamma class of titanium aluminides make them attractive for intermediate-temperature (600-850 C) aerospace applications. The oxidation and embrittlement resistance of these alloys is superior to that of the alpha(sub 2) and orthorhombic classes of titanium aluminides. However, since gamma alloys form an intermixed Al2O3/TiO2 scale in air rather than the desired continuous Al2O3 scale, oxidation resistance is inadequate at the high end of this temperature range (i.e., greater than 750-800 C). For applications at such temperatures, an oxidation-resistant coating will be needed; however, a major drawback of the oxidation-resistant coatings currently available is severe degradation in fatigue life by the coating. A new class of oxidation-resistant coatings based in the Ti-Al-Cr system offers the potential for improved fatigue life.

Surface coating metrology of carbides of cutting tools

NASA Astrophysics Data System (ADS)

Parfenov, V. D.; Basova, G. D.

2017-10-01

The coatings were studied by their main sign of the micrometric thickness by means of coating destruction and electron microscopical study of cleavage surfaces. Shock stress ruptures of heated carbides of cutting tools were performed. The discovery of the coating technology and creation of the coating structure for nonuniform and nonequilibrium conditions of the cutting process were dealt with. Multifracture microdestruction of nitride coatings, caused by complex external influences, was analysed to reveal the mechanism of interaction of elementary failures. Positive results were obtained in the form of improving the strength and wear resistance of the product, crack resistance increasing.

The flow around circular cylinders partially coated with porous media

NASA Astrophysics Data System (ADS)

Ruck, Bodo; Klausmann, Katharina; Wacker, Tobias

2012-05-01

There are indications that the flow resistance of bodies can be reduced by a porous coating or porous sheath. A few numerical investigations exists in this field, however, experimental evidence is lacking. In order to investigate this phenomenon, the drag resistance of cylinders with porous coating has been investigated qualitatively and quantitatively in wind tunnel experiments. The Reynolds number was systematically varied in the range from 104 to 1.3*105. The results show that the boundary layer over the porous surface is turbulent right from the beginning and thickens faster because of the possible vertical momentum exchange at the interface. The region of flow detachment is widened resulting in a broader area with almost vanishing low flow velocities. All in all, the measurements show that a full porous coating of the cylinders increase the flow resistance. However, the measurements show that a partial coating only on the leeward side can decrease the flow resistance of the body. This effect seems due to the fact that the recirculating velocity and the underpressure in the wake is reduced significantly through a leeward porous coating. Thus, combining a smooth non-permeable windward side with a porous-coated leeward side can lead to a reduction of the body's flow resistance. These findings can be applied advantageously in many technical areas, such as energy saving of moving bodies (cars/trains/planes) or in reducing fluid loads on submersed bodies.

Relationship Between pH and Electrochemical Corrosion Behavior of Thermal-Sprayed Ni-Al-Coated Q235 Steel in Simulated Soil Solutions

NASA Astrophysics Data System (ADS)

Wei, Wei; Wu, Xin-qiang; Ke, Wei; Xu, Song; Feng, Bing; Hu, Bo-tao

2017-09-01

Electrochemical corrosion behavior of a thermal-sprayed Ni-Al-coated Q235 steel was investigated in the simulated soil solutions at different pH values using measurements of potentiodynamic polarization curves and electrochemical impedance spectroscopy as well as surface analyses including x-ray diffraction analysis, scanning electron microscope equipped with an energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The results showed that the corrosion resistance of the Ni-Al-coated Q235 steel was dependent on the pH of the test solution. From pH = 3.53 to pH = 4.79, the corrosion resistance of the coated steel increased rapidly. In the pH range from 4.79 to 12.26, the corrosion resistance exhibited no significant change. At pH 13.25, the corrosion resistance of the sample was found to decrease. The calculated corrosion rate of Ni-Al-coated Q235 steel was lower than that of the uncoated Q235 steel and galvanized steel in all the test solutions. Over a wide range of pH values, the Ni-Al-coated Q235 steel exhibited extremely good corrosion resistance. The experimental data together with the potential-pH diagrams provided a basis for a detailed discussion of the related corrosion mechanisms of the coated steel.

Erosion-Resistant Nanocoatings for Improved Energy Efficiency in Gas Turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alman, David; Marcio, Duffles

2014-02-05

The objective of this Stage Gate IV project was to test and substantiate the viability of an erosion-resistant nanocoating for application on compressor airfoils for gas turbines in both industrial power generation and commercial aviation applications. To effectively complete this project, the National Energy Technology Laboratory’s Office of Research & Development teamed with MDS Coating Technologies Inc. (MCT), Delta Air Lines - Technical Operations Division (Delta Tech Ops), and Calpine Corporation. The coating targeted for this application was MCT’s Next Generation Coating, version 4 (NGC-v4 - with the new registered trademark name of BlackGold®). The coating is an erosion andmore » corrosion resistant composite nanostructured coating. This coating is comprised of a proprietary ceramic-metallic nano-composite construction which provides enhanced erosion resistance and also retains the aerodynamic geometry of the airfoils. The objective of the commercial aviation portion of the project was to substantiate the coating properties to allow certification from the FAA to apply an erosion-resistant coating in a commercial aviation engine. The goal of the series of tests was to demonstrate that the durability of the airfoils is not affected negatively with the application of the NGC v4 coating. Tests included erosion, corrosion, vibration and fatigue. The results of the testing demonstrated that the application of the coating did not negatively impact the properties of the blades, especially fatigue performance – which is of importance in acceptance for commercial aviation applications. The objective of the industrial gas turbine element of the project was to evaluate the coating as an enabling technology for inlet fogging during the operation of industrial gas turbines. Fluid erosion laboratory scale tests were conducted to simulate inlet fogging conditions. Results of these tests indicated that the application of the erosion resistant NGC-v4 nanocoating improved the resistance to simulated inlet fogging conditions by a factor of 10 times. These results gave confidence for a field trial at Calpine’s power plant in Corpus Christi, TX, which commenced in April 2012. This test is still on-going as of November 2013, and the nanocoated blades have accumulated over 13,000 operational hours on this specific power plant in approximately 19 months of operation.« less

High-Performance Molybdenum Coating by Wire–HVOF Thermal Spray Process

NASA Astrophysics Data System (ADS)

Tailor, Satish; Modi, Ankur; Modi, S. C.

2018-04-01

Coating deposition on many industrial components with good microstructural, mechanical properties, and better wear resistance is always a challenge for the thermal spray community. A number of thermal spray methods are used to develop such promising coatings for many industrial applications, viz. arc spray, flame spray, plasma, and HVOF. All these processes have their own limitations to achieve porous free, very dense, high-performance wear-resistant coatings. In this work, an attempt has been made to overcome this limitation. Molybdenum coatings were deposited on low-carbon steel substrates using wire-high-velocity oxy-fuel (W-HVOF; WH) thermal spray system (trade name HIJET 9610®). For a comparison, Mo coatings were also fabricated by arc spray, flame spray, plasma spray, and powder-HVOF processes. As-sprayed coatings were analyzed using x-ray diffraction, scanning electron microscopy for phase, and microstructural analysis, respectively. Coating microhardness, surface roughness, and porosity were also measured. Adhesion strength and wear tests were conducted to determine the mechanical and wear properties of the as-sprayed coatings. Results show that the coatings deposited by W-HVOF have better performance in terms of microstructural, mechanical, and wear resistance properties, in comparison with available thermal spray process (flame spray and plasma spray).

NASA Glenn/AADC-Rolls Royce Collaborated to Measure Erosion Resistance on Coated Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Sutter, James K.; Mondry, Richard; Ma, Kong; Horan, Dick; Naik, Subhash; Cupp, Randall

2003-01-01

Polymer matrix composites (PMCs) are increasingly used in aerospace and automotive applications because of their light weight and high strength-to-weight ratio relative to metals. However, a major drawback of PMCs is poor abrasion resistance, which restricts their use, especially at high temperatures. Simply applying a hard coating on PMCs to improve abrasion and erosion resistance is not effective since coating durability is short lived (ref. 1). Generally, PMCs have higher coefficients of thermal expansion than metallic or ceramic coatings have, and coating adhesion suffers because of poor interfacial adhesion strength. One technique commonly used to improve coating adhesion or durability is the use of bond coats that are interleaved between a coating and a substrate with vastly different coefficients of thermal expansion. An example of this remedy is the use of bondcoats for ceramic thermal barrier coatings on metallic turbine components (ref. 2). Prior collaborative research between the NASA Glenn Research Center and the Allison Advanced Development Company (AADC) demonstrated that bond coats sandwiched between PMCs and high-quality plasma-sprayed, erosion-resistant coatings substantially improved the erosion resistance of PMCs (ref. 3). One unresolved problem in this earlier collaboration was that there was no easy, accurate way to measure the coating erosion wear scar. Coating wear was determined by both profilometry and optical microscopy. Both techniques are time consuming. Wear measurement by optical microscopy requires sample destruction and does not provide a comprehensive measure of the entire wear volume. An even more subtle, yet critical, problem is that these erosion coatings contain two or more materials with different densities. Therefore, simply measuring specimen mass loss before and after erosion will not provide an accurate gauge for coating and/or substrate volume loss. By using a noncontact technique called scanning optical interferometry, which was recently developed at Glenn, researchers can accurately determine the wear performance of erosion-coated PMCs while preserving the sample. An example of this interferometry technique is shown in the preceding figure for an erosion-coated inlet guide vane from a Rolls Royce AE3007 regional gas turbine jet engine. Erosion was conducted with coated and uncoated PMC vanes, with the abrasive material moving at a velocity of 229 m/s at impingement angles of 20 and 90 degrees. The coatings for PMCs remarkably reduced the erosion volume loss by a factor of approximately 10. Currently, several erosion coatings for PMCs are being compared and downselected for engine testing at Rolls Royce.

Antibacterial and antibiofilm properties of yttrium fluoride nanoparticles

PubMed Central

Lellouche, Jonathan; Friedman, Alexandra; Gedanken, Aharon; Banin, Ehud

2012-01-01

Antibiotic resistance has prompted the search for new agents that can inhibit bacterial growth. Moreover, colonization of abiotic surfaces by microorganisms and the formation of biofilms is a major cause of infections associated with medical implants, resulting in prolonged hospitalization periods and patient mortality. In this study we describe a water-based synthesis of yttrium fluoride (YF3) nanoparticles (NPs) using sonochemistry. The sonochemical irradiation of an aqueous solution of yttrium (III) acetate tetrahydrate [Y(Ac)3 · (H2O)4], containing acidic HF as the fluorine ion source, yielded nanocrystalline needle-shaped YF3 particles. The obtained NPs were characterized by scanning electron microscopy and X-ray elemental analysis. NP crystallinity was confirmed by electron and powder X-ray diffractions. YF3 NPs showed antibacterial properties against two common bacterial pathogens (Escherichia coli and Staphylococcus aureus) at a μg/mL range. We were also able to demonstrate that antimicrobial activity was dependent on NP size. In addition, catheters were surface modified with YF3 NPs using a one-step synthesis and coating process. The coating procedure yielded a homogeneous YF3 NP layer on the catheter, as analyzed by scanning electron microscopy and energy dispersive spectroscopy. These YF3 NP-modified catheters were investigated for their ability to restrict bacterial biofilm formation. The YF3 NP-coated catheters were able to significantly reduce bacterial colonization compared to the uncoated surface. Taken together, our results highlight the potential to further develop the concept of utilizing these metal fluoride NPs as novel antimicrobial and antibiofilm agents, taking advantage of their low solubility and providing extended protection. PMID:23152681

Bioactive glass-ceramic coating for enhancing the in vitro corrosion resistance of biodegradable Mg alloy

NASA Astrophysics Data System (ADS)

Ye, Xinyu; Cai, Shu; Dou, Ying; Xu, Guohua; Huang, Kai; Ren, Mengguo; Wang, Xuexin

2012-10-01

In this work, a bioactive 45S5 glass-ceramic coating was synthesized on magnesium (Mg) alloy substrate by using a sol-gel dip-coating method, to improve the initial corrosion resistance of AZ31 Mg alloy. The surface morphology and phase composition of the glass-ceramic coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The coating composed of amorphous phase and crystalline phase Na2Ca2Si3O9, with the thickness of ∼1.0 μm, exhibited a uniform and crack-free surface morphology. The corrosion behavior of the uncoated and coated Mg alloy substrates was investigated by the electrochemical measurements and immersion tests in simulated body fluid (SBF). Potentiodynamic polarization tests recorded an increase of potential (Ecorr) form -1.60 V to -1.48 V, and a reduction of corrosion current density (icorr) from 4.48 μA cm-2 to 0.16 μA cm-2, due to the protection provided by the glass-ceramic coating. Immersion tests also showed the markedly improved corrosion resistance of the coated sample over the immersion period of 7 days. Moreover, after 14 days of immersion in SBF, the corrosion resistance of the coated sample declined due to the cracking of the glass-ceramic coating, which was confirmed by electrochemical impedance spectroscopy (EIS) analysis. The results suggested that the 45S5 glass-ceramic coated Mg alloy could provide a suitable corrosion behavior for use as degradable implants.

A study on microstructure and corrosion resistance of ZrO2-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

NASA Astrophysics Data System (ADS)

Zhuang, J. J.; Guo, Y. Q.; Xiang, N.; Xiong, Y.; Hu, Q.; Song, R. G.

2015-12-01

ZrO2-containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K2ZrF6) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K2ZrF6-containing electrolyte were composed of MgO, MgF2 and t-ZrO2. Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K2ZrF6. Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K2ZrF6-containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K2ZrF6-free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K2ZrF6 is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K2ZrF6 has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K2ZrF6-containing electrolyte.

Research on microstructure and wear resistance of coatings obtained by adding nanoparticles of refractory compounds in laser cladding

NASA Astrophysics Data System (ADS)

Murzakov, M. A.; Chirikov, S. N.; Markushov, Y. V.

2016-09-01

The paper is aimed at research of coatings, which are achieved by means of laser cladding with additives of nanoparticles of high-melting compounds in form of tungsten carbide and tantalum (WC and TaC). In the course of experiment, various ceramic powder concentrations were tested. Main technological characteristics were determined. Power density amounted to 0.68-0.98 MW/cm2. During the coating wear resistance measurement, it was discovered that increase in nanopowder concentration extended wear resistance of coating 2-6 times. Wear resistance measurement and wear coefficient calculation were performed using Brinell-Howarth method. The load was 15 N, load time was 10 minutes. Optical metallographic microscope Neophot-30 was used to study microstructure of the deposited coatings. To reveal microstructure of the deposited coatings, the samples were exposed to chemical etching. Elemental composition of the samples was determined by the methods of X- ray microanalysis in testing solution using electron microscope EVO-50 under acceleration voltage 10-20 kV (probe current 5-50 nA) using energy- and wavelength-dispersive spectrometers.

Improving the Corrosion Resistance of Biodegradable Magnesium Alloys by Diffusion Coating Process

NASA Astrophysics Data System (ADS)

Levy, Galit Katarivas; Aghion, Eli

Magnesium alloys suffer from accelerated corrosion in physiological environment and hence their use as a structural material for biodegradable implants is limited. The present study focuses on a diffusion coating treatment that amplifies the beneficial effect of Neodymium on the corrosion resistance of magnesium alloys. The diffusion coating layer was obtained by applying 1 µm Nd coating on EW10X04 magnesium alloy using Electron-gun evaporator and PVD process. The coated alloy was heat treated at 350°C for 3 hours in a protective atmosphere of N2+0.2%SF6. The micro structure characteristics were evaluated by SEM, XRD, and XPS; the corrosion resistance was examined by potentiodynamic polarization and EIS analysis. The corrosion resistance of the diffusion coated alloy was significantly improved compared to the uncoated material. This was related to: (i) formation of Nd2O3 in the outer scale, (ii) integration of Nd in the MgO oxide layer, and (iii) formation of secondary phase Mg41Nd5 along the grain boundaries of α-Mg.

Double coating protection of Nd-Fe-B magnets: Intergranular phosphating treatment and copper plating

NASA Astrophysics Data System (ADS)

Zheng, Jingwu; Chen, Haibo; Qiao, Liang; Lin, Min; Jiang, Liqiang; Che, Shenglei; Hu, Yangwu

2014-12-01

In this work, a double coating protection technique of phosphating treatment and copper plating was made to improve the corrosion resistance of sintered Nd-Fe-B magnets. In other words, the intergranular region of sintered Nd-Fe-B is allowed to generate passive phosphate conversion coating through phosphating treatment, followed by the copper coating on the surface of sintered Nd-Fe-B. The morphology and corrosion resistance of the phosphated sintered Nd-Fe-B were observed using SEM and electrochemical method respectively. The phosphate conversion coating was formed more preferably on the intergranular region of sintered Nd-Fe-B than on the main crystal region; just after a short time of phosphating treatment, the intergranular region of sintered Nd-Fe-B has been covered by the phosphate conversion coating and the corrosion resistance is significantly improved. With the synergistic protection of the intergranular phosphorization and the followed copper electrodeposition, the corrosion resistance of the sintered Nd-Fe-B is significantly better than that with a single phosphate film or single plating protection.

Microstructure and high-temperature oxidation resistance of TiN/Ti3Al intermetallic matrix composite coatings on Ti6Al4V alloy surface by laser cladding

NASA Astrophysics Data System (ADS)

Zhang, Xiaowei; Liu, Hongxi; Wang, Chuanqi; Zeng, Weihua; Jiang, Yehua

2010-11-01

A high-temperature oxidation resistant TiN embedded in Ti3Al intermetallic matrix composite coating was fabricated on titanium alloy Ti6Al4V surface by 6kW transverse-flow CO2 laser apparatus. The composition, morphology and microstructure of the laser clad TiN/Ti3Al intermetallic matrix composite coating were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high-temperature oxidation resistance of the composite coatings and the titanium alloy substrate, isothermal oxidation test was performed in a conventional high-temperature resistance furnace at 600°C and 800°C respectively. The result shows that the laser clad intermetallic composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like, and dendrites), and uniformly distributed in the Ti3Al matrix. It indicates that a physical and chemical reaction between the Ti powder and AlN powder occurred completely under the laser irradiation. In addition, the microhardness of the TiN/Ti3Al intermetallic matrix composite coating is 844HV0.2, 3.4 times higher than that of the titanium alloy substrate. The high-temperature oxidation resistance test reveals that TiN/Ti3Al intermetallic matrix composite coating results in the better modification of high-temperature oxidation behavior than the titanium substrate. The excellent high-temperature oxidation resistance of the laser cladding layer is attributed to the formation of the reinforced phase TiN and Al2O3, TiO2 hybrid oxide. Therefore, the laser cladding TiN/Ti3Al intermetallic matrix composite coating is anticipated to be a promising oxidation resistance surface modification technique for Ti6Al4V alloy.

Nanocoatings for Chronic Wound Repair-Modulation of Microbial Colonization and Biofilm Formation.

PubMed

Mihai, Mara Mădălina; Preda, Mădălina; Lungu, Iulia; Gestal, Monica Cartelle; Popa, Mircea Ioan; Holban, Alina Maria

2018-04-12

Wound healing involves a complex interaction between immunity and other natural host processes, and to succeed it requires a well-defined cascade of events. Chronic wound infections can be mono- or polymicrobial but their major characteristic is their ability to develop a biofilm. A biofilm reduces the effectiveness of treatment and increases resistance. A biofilm is an ecosystem on its own, enabling the bacteria and the host to establish different social interactions, such as competition or cooperation. With an increasing incidence of chronic wounds and, implicitly, of chronic biofilm infections, there is a need for alternative therapeutic agents. Nanotechnology shows promising openings, either by the intrinsic antimicrobial properties of nanoparticles or their function as drug carriers. Nanoparticles and nanostructured coatings can be active at low concentrations toward a large variety of infectious agents; thus, they are unlikely to elicit emergence of resistance. Nanoparticles might contribute to the modulation of microbial colonization and biofilm formation in wounds. This comprehensive review comprises the pathogenesis of chronic wounds, the role of chronic wound colonization and infection in the healing process, the conventional and alternative topical therapeutic approaches designed to combat infection and stimulate healing, as well as revolutionizing therapies such as nanotechnology-based wound healing approaches.

Functionally graded alumina-based thin film systems

DOEpatents

Moore, John J.; Zhong, Dalong

2006-08-29

The present invention provides coating systems that minimize thermal and residual stresses to create a fatigue- and soldering-resistant coating for aluminum die casting dies. The coating systems include at least three layers. The outer layer is an alumina- or boro-carbide-based outer layer that has superior non-wettability characteristics with molten aluminum coupled with oxidation and wear resistance. A functionally-graded intermediate layer or "interlayer" enhances the erosive wear, toughness, and corrosion resistance of the die. A thin adhesion layer of reactive metal is used between the die substrate and the interlayer to increase adhesion of the coating system to the die surface.

Corrosion resistant PEM fuel cell

DOEpatents

Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

2011-06-07

A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

High temperature oxidation resistant cermet compositions

NASA Technical Reports Server (NTRS)

Phillips, W. M. (Inventor)

1976-01-01

Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

Corrosion resistant PEM fuel cell

DOEpatents

Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

2002-01-01

A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

Bactericidal effect of polyethyleneimine capped ZnO nanoparticles on multiple antibiotic resistant bacteria harboring genes of high-pathogenicity island.

PubMed

Chakraborti, Soumyananda; Mandal, Amit Kumar; Sarwar, Shamila; Singh, Prashantee; Chakraborty, Ranadhir; Chakrabarti, Pinak

2014-09-01

Zinc oxide nanoparticles (ZnO-NP) were synthesized by alcoholic route using zinc acetate as the precursor material and lithium hydroxide as hydrolyzing agent. Further ZnO-PEI NP (derivative of ZnO-NP) was made in aqueous medium using the capping agent polyethyleneimine (PEI). The nanoparticles were characterized by XRD measurements, TEM and other techniques; the weight % of coating shell in the polymer-capped particles was determined by TGA. ZnO-PEI NP is more soluble in water than the uncapped ZnO-NP, and forms a colloidal suspension in water. PEI-capped ZnO-NP exhibited better antibacterial activity when compared with that of uncapped ZnO-NP against a range of multiple-antibiotic-resistant (MAR) Gram-negative bacterial strains harboring genes of high-pathogenicity island. ZnO-NP effectively killed these microorganisms by generating reactive oxygen species (ROS) and damaging bacterial membrane. ZnO-PEI NP at LD50 dose in combination with tetracycline showed synergistic effect to inhibit tetracycline-resistant Escherichia coli MREC33 growth by 80%. These results open up a new vista in therapeutics to use antibiotics (which have otherwise been rendered useless against MAR bacteria) in combination with minimized dosage of nanoparticles for the more effective control of MAR pathogenic bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced thermal stability of silica-coated gold nanorods for photoacoustic imaging and image-guided therapy.

PubMed

Chen, Yun-Sheng; Frey, Wolfgang; Kim, Seungsoo; Homan, Kimberly; Kruizinga, Pieter; Sokolov, Konstantin; Emelianov, Stanislav

2010-04-26

Photothermal stability and, therefore, consistency of both optical absorption and photoacoustic response of the plasmonic nanoabsorbers is critical for successful photoacoustic image-guided photothermal therapy. In this study, silica-coated gold nanorods were developed as a multifunctional molecular imaging and therapeutic agent suitable for image-guided photothermal therapy. The optical properties and photothermal stability of silica-coated gold nanorods under intense irradiation with nanosecond laser pulses were investigated by UV-Vis spectroscopy and transmission electron microscopy. Silica-coated gold nanorods showed increased photothermal stability and retained their superior optical properties under much higher fluences. The changes in photoacoustic response of PEGylated and silica-coated nanorods under laser pulses of various fluences were compared. The silica-coated gold nanorods provide a stable photoacoustic signal, which implies better imaging capabilities and make silica-coated gold nanorods a promising imaging and therapeutic nano-agent for photoacoustic imaging and image-guided photothermal therapy.

Enhanced thermal stability of silica-coated gold nanorods for photoacoustic imaging and image-guided therapy

PubMed Central

Chen, Yun-Sheng; Frey, Wolfgang; Kim, Seungsoo; Homan, Kimberly; Kruizinga, Pieter; Sokolov, Konstantin; Emelianov, Stanislav

2010-01-01

Photothermal stability and, therefore, consistency of both optical absorption and photoacoustic response of the plasmonic nanoabsorbers is critical for successful photoacoustic image-guided photothermal therapy. In this study, silica-coated gold nanorods were developed as a multifunctional molecular imaging and therapeutic agent suitable for image-guided photothermal therapy. The optical properties and photothermal stability of silica-coated gold nanorods under intense irradiation with nanosecond laser pulses were investigated by UV-Vis spectroscopy and transmission electron microscopy. Silica-coated gold nanorods showed increased photothermal stability and retained their superior optical properties under much higher fluences. The changes in photoacoustic response of PEGylated and silica-coated nanorods under laser pulses of various fluences were compared. The silica-coated gold nanorods provide a stable photoacoustic signal, which implies better imaging capabilities and make silica-coated gold nanorods a promising imaging and therapeutic nano-agent for photoacoustic imaging and image-guided photothermal therapy. PMID:20588732

Improvement of corrosion resistance and antibacterial effect of NiTi orthopedic materials by chitosan and gold nanoparticles

NASA Astrophysics Data System (ADS)

Ahmed, Rasha A.; Fadl-allah, Sahar A.; El-Bagoury, Nader; El-Rab, Sanaa M. F. Gad

2014-02-01

Biocomposite consists of gold nanoparticles (AuNPs) and a natural polymer as Chitosan (CS) was electrodeposited over NiTi alloy to improve biocompatibility, biostability, surface corrosion resistance and antibacterial effect for orthopedic implantation. The forming process and surface morphology of this biocomposite coats over NiTi alloy were studied. The results showed that the nm-scale gold particles were embedded in the composite forming compact, thick and smooth coat. Elemental analysis revealed significant less Ni ion release from the coated NiTi alloy compared with the uncoated one by 20 fold. Furthermore, the electrochemical corrosion measurements indicated that AuNPs/CS composite coat was effective for improving corrosion resistance in different immersion times and at all pH values, which suggests that the coated NiTi alloys have potential for orthopedic applications. Additionally, the efficiencies of the biocomposite coats for inhibiting bacterial growth indicate high antibacterial effect.

Development of an Anti-Corrosion Conductive Nano Carbon Coating Layer on Metal Bipolar Plates.

PubMed

Yeo, Kiho; Kim, Juyong; Kim, Jongryoul

2018-09-01

For automotive applications of polymer electrolyte membrane fuel cells, the enhancement of the corrosion resistance of metal bipolar plates has been a critical issue with regard to the lifespan of fuel cell stacks. In this paper, we present a novel method for increasing the lifespan by means of a conductive carbon coating on bipolar plates. Conductive carbon films were plasma coated onto metal bipolar plates in a vacuum at various temperatures. As a result, 316L stainless plates with a 10-nm-thick carbon coating layer on a 20-nm-thick CrN undercoat layer showed-contact resistance of 10.71 mΩcm2@10 kgf/cm2 and a corrosion current of 0.5 μA/cm2@0.6 V. This thin coating layer with high conductivity and excellent corrosion resistance suggests a new, effective coating method for the mass production of metal bipolar plates.

Tribological tests of wear-resistant coatings used in the production of drill bits of horizontal and inclined drilling

NASA Astrophysics Data System (ADS)

Maslov, A. L.; Markova, I. Yu; Zakharova, E. S.; Polushin, N. I.; Laptev, A. I.

2017-05-01

It is known that modern drilling bit body undergoes significant abrasive wear in the contact area with the solid and the retracted cuttings. For protection of the body rationally use wear-resistant coating, which is welded directly to the body of bit. Before mass use of the developed coverings they need to be investigated by various methods that it was possible to characterize coatings and on the basis of the obtained data to perform optimization of both composition of coatings and technology. Such methods include microstructural studies tribological tests, crack resistance and others. This work is devoted to the tribological tests of imported brand of coatings WokaDur NiA and and domestic brand of coating HR-6750 (both brands manufactured by Ltd “Oerlikon Metco Rus”), used to protect the bit body from abrasive wear.

CNT coated thread micro-electro-mechanical system for finger proprioception sensing

NASA Astrophysics Data System (ADS)

Shafi, A. A.; Wicaksono, D. H. B.

2017-04-01

In this paper, we aim to fabricate cotton thread based sensor for proprioceptive application. Cotton threads are utilized as the structural component of flexible sensors. The thread is coated with multi-walled carbon nanotube (MWCNT) dispersion by using facile conventional dipping-drying method. The electrical characterization of the coated thread found that the resistance per meter of the coated thread decreased with increasing the number of dipping. The CNT coated thread sensor works based on piezoresistive theory in which the resistance of the coated thread changes when force is applied. This thread sensor is sewed on glove at the index finger between middle and proximal phalanx parts and the resistance change is measured upon grasping mechanism. The thread based microelectromechanical system (MEMS) enables the flexible sensor to easily fit perfectly on the finger joint and gives reliable response as proprioceptive sensing.

Investigation on the relationship between NbC and wear-resistance of Fe matrix composite coatings with different C contents

NASA Astrophysics Data System (ADS)

Zhao, Changchun; Zhou, Yefei; Xing, Xiaolei; Liu, Sha; Ren, Xuejun; Yang, Qingxiang

2018-05-01

The wear resistance of Fe-based composite coating is significantly related with the character of carbides and matrix, which could be strongly affected by C content in it. In this work, the Fe-based composite coatings with different C contents were prepared. The microstructure and phase structure of the coatings were analyzed by scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and X-ray diffractometer (XRD). The hardness and wear resistance of the coatings were determined. Then the hardness and brittleness of carbon poor niobium carbides were calculated by first principles calculation. The results show that, the phase structures of the coatings are mainly composed of NbC, γ phase (retained austenite) and α phase (martensite). With the increase of C content, the retained austenite appears and C content of martensite is increased. The hardness of the coatings are increased from HRC 22 to HRC 59. The distribution and morphology of NbC are changed with the increase of C content. The NbC precipitated in reticular grain boundary can be observed when C content is 0.4 wt.% C (C-1). NbC turn into granular and small rod morphology when C content increases to 0.8 wt.% C (C-2). The cracks and defects cannot been found on the surface of the coating when C content is 1.2 wt.% C(C-3), whose hardness is HRC 58 and wear loss is 0.27 g/N cm2 in 8 h. The flaky M7C3 carbide precipitates on the coating when C content is 1.4 wt.% C(C-4), which weaken the wear resistance of the matrix. Compared with the hardfacing coatings with different C contents, the C-3 coating processes higher hardness and wear resistance.

ETV Program Report: Coatings for Wastewater Collection ...

EPA Pesticide Factsheets

The Standard Cement Materials, Inc. Standard Epoxy Coating 4553™ (SEC 4553) epoxy coating used for wastewater collection system rehabilitation was evaluated by EPA’s Environmental Technology Verification Program under laboratory conditions at the Center for Innovative Grouting Material and Technology (CIGMAT) Laboratory at the University of Houston. Testing was conducted over a period of six months to evaluate the coating’s (1) chemical resistance and (2) bonding strength for infrastructure applications. For chemical resistance, coated concrete and clay bricks with holidays (holes created in the coating) were used to evaluate the chemical resistance of the coating/substrate bond under a corrosive environment. Twenty coated concrete (dry and wet) and 20 coated clay brick (dry and wet) specimens were exposed to DI water and sulfuric acid solution (pH=1), and the specimens were visually inspected and weight changes measured. Evaluation of the coating-to-substrate bonding strength was determined using two modified ASTM test methods – one to determine bond strength of the coating with two specimens sandwiched together using the coating, and the second to determine the bond strength by applying a tensile load to the coating applied to specimens of each substrate. Forty-eight bonding tests were performed over the six month evaluation. The tests resulted in the following conclusions about Standard Cement’s SEC 4553 coating: • After the six-month chemi

Interface activation and surface characteristics of Ti/TiN/HA coated sintered stainless steels

NASA Astrophysics Data System (ADS)

Choe, Han-Cheol; Ko, Yeong-Mu

2006-02-01

Interface activation and surface characteristics of Ti/TiN/HA film coated sintered stainless steels (SSS) have been investigated by electrochemical and biocompatibility tests. HA (hydroxyapatite), Ti, and Ti/TiN film coatings were applied using electron-beam deposition method (EB-PVD). Ti, Ti/TiN, and Ti/TiN/HA film coated surfaces and layers were investigated by SEM and XPS. The coated films showed micro-columnar structure, and Ti/TiN/HA films were denser than Ti or HA-only film. The corrosion resistance of the HA coating was similar to that of Ti/TiN/HA film coating when Cu content reached 4 wt.%, but the corrosion resistance of the HA coating decreased when Cu content increased from 4 wt.% in 0.9% NaCl solution. Therefore, HA-only coating could ensure corrosion resistance when Cu content does not exceed 4 wt.%. The results of biocompatibility tests of SSS on dogs showed that bone formation and biocompatibility were favorable when Cu content did not exceed 4 wt.%. The biocompatibility with bone was generally favorable in Ti/TiN/HA film coating and HA-only coating, while bone formation was somewhat faster for the HA film coated surface than for the Ti/TiN/HA film coating. Also, good cell growth and osseointegration without toxicity were observed.

Effect of Ultraviolet Exposure on Impact Resistance of Ophthalmic Lenses.

PubMed

Chou, B Ralph; Dain, Stephen J; Cheng, Brian B

2015-12-01

To investigate the effect of ultraviolet radiation (UVR) on the impact resistance of organic ophthalmic lens materials. Plano power CR39, Phoenix, Trilogy, and polycarbonate lenses with various scratch-resistant (SR) and/or antireflection (AR) coatings were obtained in batches of 40 units. All lenses had a nominal thickness of 2 mm. Half of each batch was conditioned following the European Standard EN 168 protocol for the test of resistance to UVR (exposed group). The remaining lenses comprised an unexposed group for that combination of lens substrate and coating treatment. Each group was subjected to ballistic impact with 6-mm steel balls following the ZEST protocol to determine its mean breakage velocity. The difference in mean breakage velocity between exposed and unexposed groups of each combination of lens substrate and coating was assessed for statistical significance. Exposed uncoated CR39 showed a reduction in fracture velocity of 10.3 m/s whereas CR39 with ultra hard coat had a reduction of 3.5 m/s and CR39 with AR and SR coating had a reduction of 4.1 m/s. Scratch-resistant coated Phoenix had a reduction of 4.8 m/s whereas AR-coated Phoenix had a reduction of 3.7 m/s. The corresponding reductions for Trilogy were 3.9 and 17.8 m/s. All differences were significant at the p level of less than 0.05. Although we were unable to break unexposed SR-coated polycarbonate lenses with our test apparatus, exposed SR-coated polycarbonate had a mean breakage velocity of 142 m/s. Our data suggest that extended UVR exposure causes a significant reduction in the impact resistance of the ophthalmic lens substrates commonly used for occupational eye protectors. Protective lenses that have been exposed to high levels of UVR for extended periods should be replaced regularly to maintain optimal impact protection, even if they do not show visible damage owing to wear and tear.

Effects of Laser Re-melting on the Corrosion Properties of HVOF Coatings

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Toor, I. H.; Patel, F.; Baig, M. A.

2013-05-01

HVOF coating of Inconel 625 powder on carbon steel is carried out. Laser melting of the resulting coating is realized to improve coating structural integrity. Morphological and microstructural changes are examined in the coating prior and after laser treatment process using scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction (XRD). The residual stress developed is measured on the surface vicinity of the laser-treated coating using the XRD technique. The corrosion resistance of the laser-treated and untreated coating surfaces is measured, incorporating the potentiodynamic tests in 0.5 M NaCl aqueous solution. It is found that laser treatment reduces the pores and produces cellular structures with different sizes and orientations in the coating. Laser-controlled melting improves the corrosion resistance of the coating surface.

Influence of Carbon interstitials to Ti1-xMexN (Me = Zr, Al, Cr) coatings by pulsed laser ablation on wear resistance

NASA Astrophysics Data System (ADS)

Jeon, Seol; Hong, Eunpyo; Kwon, Se-Hun; Lee, Heesoo

2018-06-01

The wear resistance of Ti1-xMexN (Me = Zr, Al, Cr) coatings by the laser carburization process was investigated in terms of local atomic structural changes. The repeated pulsed laser ablation was performed to the Ti1-xMexN coating surfaces after Graphite paste was covered. The friction coefficients of the coating specimens were decreased from ∼0.7 to 0.2, and the formation of cracks and debris was suppressed by implementing the laser ablation process. ToF-SIMS depth profiles showed that the laser carburization helps Carbon penetrate into the coating layer as deep as ∼20 nm below its surface. XPS and XAFS analyses revealed that the improvement of the wear resistance of the coatings was achieved not by formation of TiC or ZrC lattices on the coatings surfaces but by Carbon interstitials to the Ti1-xMexN lattices.

Formation of interfacial compounds and the effects on stripping behaviors of a cold-sprayed Zn-Al coating on interstitial-free steel

NASA Astrophysics Data System (ADS)

Liang, Y. L.; Wang, Z. B.; Zhang, J. B.; Lu, K.

2015-06-01

By means of cold spray, a Zn-Al coating was successfully deposited on an interstitial-free (IF) steel sheet. The formation of interfacial compounds between the coating and the IF steel was studied during diffusion annealing at 400 °C. And its correlations with the stripping behaviors of the coating were investigated by using a three-point bending method. The results showed that Fe-Zn and Fe-Al-Zn compounds begin to form at the coating/substrate interface after an annealing duration of 60 min, and the stripping resistance increases slightly before that duration and then decreases significantly by further increasing annealing duration. The enhanced stripping resistance at the earlier stage might be due to the modifications of microstructure and deformation compatibility of the sprayed coating, while the decreased stripping resistance at the later stage is related to the high stress concentration at the interface of the formed brittle Fe-Al-Zn phase and the Zn-Al coating.

High temperature oxidation behavior of interconnect coated with LSCF and LSM for solid oxide fuel cell by screen printing

NASA Astrophysics Data System (ADS)

Lee, Shyong; Chu, Chun-Lin; Tsai, Ming-Jui; Lee, Jye

2010-01-01

The current study examined the effect of La 0.6Sr 0.4Co 0.2Fe 0.8O 3 (LSCF) and La 0.7Sr 0.3MnO 3 (LSM) coatings on the electrical properties and oxidation resistance of Crofer22 APU at 800 °C hot air. LSCF and LSM were coated on Crofer22 APU by screen printing and sintered over temperatures ranging from 1000 to 1100 °C in N 2. The coated alloy was first checked for compositions, morphology and interface conditions and then treated in a simulated oxidizing environment at 800 °C for 200 h. After measuring the long-term electrical resistance, the area specific resistance (ASR) at 800 °C for the alloy coated with LSCF was less than its counterpart coated with LSM. This work used LSCF coating as a metallic interconnect to reduce working temperature for the solid oxide fuel cell.

Behavior of an improved Zr fuel cladding with oxidation resistant coating under loss-of-coolant accident conditions

NASA Astrophysics Data System (ADS)

Park, Dong Jun; Kim, Hyun Gil; Jung, Yang Il; Park, Jung Hwan; Yang, Jae Ho; Koo, Yang Hyun

2016-12-01

This study investigates protective coatings for improving the high temperature oxidation resistance of Zr fuel claddings for light water nuclear reactors. FeCrAl alloy and Cr layers were deposited onto Zr plates and tubes using cold spraying. For the FeCrAl/Zr system, a Mo layer was introduced between the FeCrAl coating and the Zr matrix to prevent inter-diffusion at high temperatures. Both the FeCrAl and Cr coatings improved the oxidation resistance compared to that of the uncoated Zr alloy when exposed to a steam environment at 1200 °C. The ballooning behavior and mechanical properties of the coated cladding samples were studied under simulated loss-of-coolant accident conditions. The coated samples showed higher burst temperatures, lower circumferential strain, and smaller rupture openings compared to the uncoated Zr. Although 4-point bend tests of the coated samples showed a small increase in the maximum load, ring compression tests of a sectioned sample showed increased ductility.

RGDC Peptide-Induced Biomimetic Calcium Phosphate Coating Formed on AZ31 Magnesium Alloy

PubMed Central

Cao, Lin; Wang, Lina; Fan, Lingying; Xiao, Wenjun; Lin, Bingpeng; Xu, Yimeng; Liang, Jun; Cao, Baocheng

2017-01-01

Magnesium alloys as biodegradable metal implants have received a lot of interest in biomedical applications. However, magnesium alloys have extremely high corrosion rates a in physiological environment, which have limited their application in the orthopedic field. In this study, calcium phosphate compounds (Ca–P) coating was prepared by arginine–glycine–aspartic acid–cysteine (RGDC) peptide-induced mineralization in 1.5 simulated body fluid (SBF) to improve the corrosion resistance and biocompatibility of the AZ31 magnesium alloys. The adhesion of Ca–P coating to the AZ31 substrates was evaluated by a scratch test. Corrosion resistance and cytocompatibility of the Ca–P coating were investigated. The results showed that the RGDC could effectively promote the nucleation and crystallization of the Ca–P coating and the Ca–P coating had poor adhesion to the AZ31 substrates. The corrosion resistance and biocompatibility of the biomimetic Ca–P coating Mg alloys were greatly improved compared with that of the uncoated sample. PMID:28772717

CXCR4-targeted lipid-coated PLGA nanoparticles deliver sorafenib and overcome acquired drug resistance in liver cancer.

PubMed

Gao, Dong-Yu; Lin, Ts-Ting; Sung, Yun-Chieh; Liu, Ya Chi; Chiang, Wen-Hsuan; Chang, Chih-Chun; Liu, Jia-Yu; Chen, Yunching

2015-10-01

Sorafenib, a multikinase inhibitor, has been used as an anti-angiogenic agent against highly vascular hepatocellular carcinoma (HCC) - yet associated with only moderate therapeutic effect and the high incidence of HCC recurrence. We have shown intratumoral hypoxia induced by sorafenib activated C-X-C receptor type 4 (CXCR4)/stromal-derived factor 1α (SDF1α) axis, resulting in polarization toward a tumor-promoting microenvironment and resistance to anti-angiogenic therapy in HCC. Herein, we formulated sorafenib in CXCR4-targeted lipid-coated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) modified with a CXCR4 antagonist, AMD3100 to systemically deliver sorafenib into HCC and sensitize HCC to sorafenib treatment. We demonstrated that CXCR4-targeted NPs efficiently delivered sorafenib into HCCs and human umbilical vein endothelial cells (HUVECs) to achieve cytotoxicity and anti-angiogenic effect in vitro and in vivo. Despite the increased expression of SDF1α upon the persistent hypoxia induced by sorafenib-loaded CXCR4-targeted NPs, AMD3100 attached to the NPs can block CXCR4/SDF1α, leading to the reduced infiltration of tumor-associated macrophages, enhanced anti-angiogenic effect, a delay in tumor progression and increased overall survival in the orthotopic HCC model compared with other control groups. In conclusion, our results highlight the clinical potential of CXCR4-targeted NPs for delivering sorafenib and overcoming acquired drug resistance in liver cancer. Copyright © 2015 Elsevier Ltd. All rights reserved.

Protection of alodine coatings from thermal aging by removable polymer coatings.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagstaff, Brett R.; Bradshaw, Robert W.; Whinnery, LeRoy L., Jr.

2006-12-01

Removable polymer coatings were evaluated as a means to suppress dehydration of Alodine chromate conversion coatings during thermal aging and thereby retain the corrosion protection afforded by Alodine. Two types of polymer coatings were applied to Alodine-treated panels of aluminum alloys 7075-T73 and 6061-T6 that were subsequently aged for 15 to 50 hours at temperatures between 135 F to 200 F. The corrosion resistance of the thermally aged panels was evaluated, after stripping the polymer coatings, by exposure to a standard salt-fog corrosion test and the extent of pitting of the polymer-coated and untreated panels compared. Removable polymer coatings mitigatedmore » the loss of corrosion resistance due to thermal aging experienced by the untreated alloys. An epoxide coating was more effective than a fluorosilicone coating as a dehydration barrier.« less

Optical coatings for laser fusion applications

NASA Astrophysics Data System (ADS)

Lowdermilk, W. H.; Milam, D.; Rainer, F.

1980-04-01

Lasers for fusion experiments use thin-film dielectric coatings for reflecting antireflecting and polarizing surface elements. Coatings are most important to the Nd:glass laser application. The most important requirements of these coatings are accuracy of the average value of reflectance and transmission, uniformity of amplitude and phase front of the reflected or transmitted light, and laser damage threshold. Damage resistance strongly affects the laser's design and performance. The success of advanced lasers for future experiments and for reactor applications requires significant developments in damage resistant coatings for ultraviolet laser radiation.

Effect of negative bias on TiAlSiN coating deposited on nitrided Zircaloy-4

NASA Astrophysics Data System (ADS)

Jun, Zhou; Zhendong, Feng; Xiangfang, Fan; Yanhong, Liu; Huanlin, Li

2018-01-01

TiAlSiN coatings were deposited on the nitrided Zircaloy-4 by multi-arc ion plating at -100 V, -200 V and -300 V. In this study, the high temperature oxidation behavior of coatings was tested by a box-type resistance furnace in air for 3 h at 800 °C; the macro-morphology of coatings was observed and analyzed by a zoom-stereo microscope; the micro-morphology of coatings was analyzed by a scanning electron microscopy (SEM), and the chemical elements of samples were analyzed by an energy dispersive spectroscopy(EDS); the adhesion strength of the coating to the substrate was measured by an automatic scratch tester; and the phases of coatings were analyzed by an X-ray diffractometer(XRD). Results show that the coating deposited at -100 V shows better high temperature oxidation resistance behavior, at the same time, Al elements contained in the coating is of the highest amount, meanwhile, the adhesion strength of the coating to the substrate is the highest, which is 33N. As the bias increases, high temperature oxidation resistance behavior of the coating weakens first and then increases, the amount of large particles on the surface of the coating increases first and then decreases whereas the density of the coating decreases first and then increases, and adhesion strength of the coating to the substrate increases first and then weakens. The coating's quality is relatively poor when the bias is -200 V.

Electrodeposition and Characterization of Ni-Al2O3 Nanocomposite Coatings on Steel

NASA Astrophysics Data System (ADS)

Akhtar, Khalida; Khan, Zia Ullah; Gul, Muhammad; Zubair, Naila; Shah, Syed Sajjad Ali

2018-05-01

Monodispersed alumina particles were synthesized by the homogeneous precipitation under reflux boiling. The particles were employed as reinforcement additives in the electrodeposited Ni-Al2O3 composite coatings on steel. The deposited pure Ni and Ni-Al2O3 composite coatings were analyzed by SEM, XRD, and microhardness tester. The wear resistance and friction coefficient of the coated samples were determined by using a ball-on-disk tribometer. Furthermore, XRD analysis showed that coating temperature and the presence of particles in the deposited coatings had a noticeable effect on the preferred orientation of the crystalline faces of the nickel grains. Significant differences were noted in the texture coefficient of the pure Ni and Ni-Al2O3 composite coatings produced at different temperatures. These differences were attributed to the changes in the microstructure of the matrix caused by the embedded Al2O3 particles. Results revealed that wear resistance and the friction coefficient were turned out to be higher and smaller, respectively, for the composite coatings as compared to pure Ni coating at a given sliding distance. It was noted that the corrosion resistance of these specimens increased in the following order: bare substrate < pure Ni coating < Ni-Al2O3 nanocomposite coatings.

Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

NASA Astrophysics Data System (ADS)

Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

2016-05-01

Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

Tailoring the heat transfer on the injection moulding cavity by plasma sprayed ceramic coatings

NASA Astrophysics Data System (ADS)

Bobzin, K.; Hopmann, Ch; Öte, M.; Knoch, M. A.; Alkhasli, I.; Dornebusch, H.; Schmitz, M.

2017-03-01

Inhomogeneous material shrinkage in injection moulding can cause warpage in thermoplastic components. To minimise the deformations of the injection moulding parts, the heat transfer during the cooling phase can be adjusted according to the local cooling demand on the surface of the mould cavity by means of plasma sprayed coatings with locally variable thermal resistance over the surface of the mould. Thermal resistance is a function of thermal conductivity and thickness of the coatings, where thermal conductivity of thermal barrier coatings can be adjusted by altering the chemical composition and the microstructure, which is depending on the thickness. This work evaluates the application of plasma sprayed coatings with variable thickness as thermal barrier coatings in the mould cavity. The thermal resistance of the coating and thereby the heat transfer from the melt into the mould will be influenced locally by varying the coating thickness over the cavity area according to the local cooling demand. Using the laser flash method, the thermal conduction of coatings with different thicknesses will be determined. On the basis of the experimentally determined thermal conduction, the effect of the coatings on the temperature field of the mould cavity will be numerically calculated and the required thickness distribution of the coating for an optimal temperature gradient will be determined.

Applications in the Nuclear Industry for Thermal Spray Amorphous Metal and Ceramic Coatings

NASA Astrophysics Data System (ADS)

Blink, J.; Farmer, J.; Choi, J.; Saw, C.

2009-06-01

Amorphous metal and ceramic thermal spray coatings have been developed with excellent corrosion resistance and neutron absorption. These coatings, with further development, could be cost-effective options to enhance the corrosion resistance of drip shields and waste packages, and limit nuclear criticality in canisters for the transportation, aging, and disposal of spent nuclear fuel. Iron-based amorphous metal formulations with chromium, molybdenum, and tungsten have shown the corrosion resistance believed to be necessary for such applications. Rare earth additions enable very low critical cooling rates to be achieved. The boron content of these materials and their stability at high neutron doses enable them to serve as high efficiency neutron absorbers for criticality control. Ceramic coatings may provide even greater corrosion resistance for waste package and drip shield applications, although the boron-containing amorphous metals are still favored for criticality control applications. These amorphous metal and ceramic materials have been produced as gas-atomized powders and applied as near full density, nonporous coatings with the high-velocity oxy-fuel process. This article summarizes the performance of these coatings as corrosion-resistant barriers and as neutron absorbers. This article also presents a simple cost model to quantify the economic benefits possible with these new materials.

Modification of UV absorption profile of polymer film reflectors to increase solar-weighted reflectance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorgensen, Gary; Gee, Randall C.; White, David

Provided are reflective thin film constructions including a reduced number of layers, which provides for increased solar-weighted hemispherical reflectance and durability. Reflective films include those comprising an ultraviolet absorbing abrasion resistant coating over a metal layer. Also provided are ultraviolet absorbing abrasion resistant coatings and methods for optimizing the ultraviolet absorption of an abrasion resistant coating. Reflective films disclosed herein are useful for solar reflecting, solar collecting, and solar concentrating applications, such as for the generation of electrical power.

Optically transparent, scratch-resistant, diamond-like carbon coatings

DOEpatents

He, Xiao-Ming; Lee, Deok-Hyung; Nastasi, Michael A.; Walter, Kevin C.; Tuszewski, Michel G.

2003-06-03

A plasma-based method for the deposition of diamond-like carbon (DLC) coatings is described. The process uses a radio-frequency inductively coupled discharge to generate a plasma at relatively low gas pressures. The deposition process is environmentally friendly and scaleable to large areas, and components that have geometrically complicated surfaces can be processed. The method has been used to deposit adherent 100-400 nm thick DLC coatings on metals, glass, and polymers. These coatings are between three and four times harder than steel and are therefore scratch resistant, and transparent to visible light. Boron and silicon doping of the DLC coatings have produced coatings having improved optical properties and lower coating stress levels, but with slightly lower hardness.

High Velocity Oxidation and Hot Corrosion Resistance of Some ODS Alloys

NASA Technical Reports Server (NTRS)

Lowell, C. E.; Deadmore, D. L.

1977-01-01

Several oxide dispersion strengthened (ODS) alloys were tested for cyclic, high velocity, oxidation, and hot corrosion resistance. These results were compared to the resistance of an advanced, NiCrAl coated superalloy. An ODS FeCrAl were identified as having sufficient oxidation and hot corrosion resistance to allow potential use in an aircraft gas turbine without coating.

Optically transparent and durable Al2O3 coatings for harsh environments by ultra short pulsed laser deposition

NASA Astrophysics Data System (ADS)

Korhonen, Hannu; Syväluoto, Aki; Leskinen, Jari T. T.; Lappalainen, Reijo

2018-01-01

Nowadays, an environmental protection is needed for a number of optical applications in conditions quickly impairing the clarity of optical surfaces. Abrasion resistant optical coatings applied onto plastics are usually based on alumina or polysiloxane technology. In many applications transparent glasses and ceramics need a combination of abrasive and chemically resistant shielding or other protective solutions like coatings. In this study, we intended to test our hypothesis that clear and pore free alumina coating can be uniformly distributed on glass prisms by ultra short pulsed laser deposition (USPLD) technique to protect the sensitive surfaces against abrasives. Abrasive wear tests were carried out by the use of SiC emery paper using specified standard procedures. After the wear tests the measured transparencies of coated prisms turned out to be close those of the prisms before coating. The coating on sensitive surfaces consistently displayed enhanced wear resistance exhibiting still high quality, even after severe wear testing. Furthermore, the coating modified the surface properties towards hydrophobic nature in contrast to untreated prisms, which became very hydrophilic especially due to wear.

Influence of Fluoride Ion Concentrations on the Corrosion Behavior of Ta2N Nanocrystalline Coating for Dental Implant Applications

NASA Astrophysics Data System (ADS)

Xu, Jiang; Ma, Jin Jin; Munroe, Paul; Xie, Zong-Han

The development of new corrosion-resistant coatings is often challenging, but strongly driven by the potential benefits such coatings hold. A nanostructured Ta2N coating was deposited on a Ti-6Al-4V substrate in an Ar-N atmosphere using a double cathode glow discharge plasma method with the aim being to improve its corrosion resistance in oral environments. The microstructure of the coating was investigated by a range of methods including XRD, SEM-EDS and TEM. The as-deposited coating exhibited densely packed fibrous structure and the individual fibers were composed of equiaxed grains with an average grain size ˜13nm, arranged along the longitudinal axis of the individual fibers. The electrochemical behavior of the Ta2N nanocrystalline coating was characterized in artificial saliva containing different NaF concentrations by a range of electrochemical techniques, including potentiodynamic measurement, EIS, capacitance and PZFC measurements. It was shown that the coating possessed superior corrosion resistance compared to uncoated Ti-6Al-4V, because its passive film exhibited higher stability against the fluoride ion attack.

Protection of 310l Stainless Steel from Wear at Elevated Temperatures using Conicraly Thermal Spray Coatings with and without Sic Addition

NASA Astrophysics Data System (ADS)

Zhang, Yan; Zhang, Tao; Li, Kaiyang; Li, Dongyang

2017-10-01

Due to its high oxidation resistance, 310L stainless steel is often used for thermal facilities working at high-temperatures. However, the steel may fail prematurely at elevated temperatures when encounter surface mechanical attacks such as wear. Thermal spray coatings have been demonstrated to be effective in protecting the steel from wear at elevated temperatures. In this study, we investigated the effectiveness of high velocity oxy-fuel(HVOF) spraying CoNiCrAlY/SiC coatings in resisting wear of 310L stainless steel at elevated temperature using a pin-on-disc wear tester. In order to further improve the performance of the coating, 5%SiC was added to the coating. It was demonstrated that the CoNiCrAlY/SiC coating after heat treatment markedly suppressed wear. However, the added SiC particles did not show benefits to the wear resistance of the coating. Microstructures of CoNiCrAlY coatings with and without the SiC addition were characterized in order to understand the mechanism responsible for the observed phenomena.

Microstructure and high temperature oxidation resistance of Ti-Ni gradient coating on TA2 titanium alloy fabricated by laser cladding

NASA Astrophysics Data System (ADS)

Liu, Fencheng; Mao, Yuqing; Lin, Xin; Zhou, Baosheng; Qian, Tao

2016-09-01

To improve the high temperature oxidation resistance of TA2 titanium alloy, a gradient Ni-Ti coating was laser cladded on the surface of the TA2 titanium alloy substrate, and the microstructure and oxidation behavior of the laser cladded coating were investigated experimentally. The gradient coating with a thickness of about 420-490 μm contains two different layers, e.g. a bright layer with coarse equiaxed grain and a dark layer with fine and columnar dendrites, and a transition layer with a thickness of about 10 μm exists between the substrate and the cladded coating. NiTi, NiTi2 and Ni3Ti intermetallic compounds are the main constructive phases of the laser cladded coating. The appearance of these phases enhances the microhardness, and the dense structure of the coating improves its oxidation resistance. The solidification procedure of the gradient coating is analyzed and different kinds of solidification processes occur due to the heat dissipation during the laser cladding process.

Influence of heat treatment on bond strength and corrosion resistance of sol-gel derived bioglass-ceramic coatings on magnesium alloy.

PubMed

Shen, Sibo; Cai, Shu; Xu, Guohua; Zhao, Huan; Niu, Shuxin; Zhang, Ruiyue

2015-05-01

In this study, bioglass-ceramic coatings were prepared on magnesium alloy substrates through sol-gel dip-coating route followed by heat treatment at the temperature range of 350-500°C. Structure evolution, bond strength and corrosion resistance of samples were studied. It was shown that increasing heat treatment temperature resulted in denser coating structure as well as increased interfacial residual stress. A failure mode transition from cohesive to adhesive combined with a maximum on the measured bond strength together suggested that heat treatment enhanced the cohesion strength of coating on the one hand, while deteriorated the adhesion strength of coating/substrate on the other, thus leading to the highest bond strength of 27.0MPa for the sample heat-treated at 450°C. This sample also exhibited the best corrosion resistance. Electrochemical tests revealed that relative dense coating matrix and good interfacial adhesion can effectively retard the penetration of simulated body fluid through the coating, thus providing excellent protection for the underlying magnesium alloy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Composite starch-based coatings applied to strawberries (Fragaria ananassa).

PubMed

García, M A; Martino, M N; Zaritzky, N E

2001-08-01

Starch-based coatings were used to the extend storage life of strawberries (Fragaria ananassa) stored at 0 degree C and 84.8% relative humidity. Effects of coating formulation (including starch type, plasticizer, lipid and antimicrobial agent) were analysed with respect to fruit quality. Plasticizer addition was necessary for film and coating integrity to avoid pores and cracks. Plasticizer presence reduced weight losses and maintained surface colour of fruits. Amylomaize coatings showed lower water vapour and gas permeabilities and decreased weight losses for longer periods than corn starch ones. Coatings with sorbitol showed lower permeabilities than glycerol ones. Coatings with antimicrobial agents decreased microbial counts, extending storage life of coated fruits by 10 to 14 days in comparison to the control. The addition of 2 g/l sunflower oil to the formulations decreased the water vapour permeability of starch-based films, maintained the surface colour of coated fruits and controlled effectively fruit weight losses during storage. Lipid addition minimized the effects of starch and plasticizer types. Composite starch-based coatings showed selective gas permeability (CO2 higher than O2) which helps to delay senescence of fruits.

Characterization and corrosion property of nano-rod-like HA on fluoride coating supported on Mg-Zn-Ca alloy.

PubMed

Feng, Yashan; Zhu, Shijie; Wang, Liguo; Chang, Lei; Yan, Bingbing; Song, Xiaozhe; Guan, Shaokang

2017-06-01

The poor corrosion resistance of biodegradable magnesium alloys is the dominant factor that limits their clinical application. In this study, to deal with this challenge, fluoride coating was prepared on Mg-Zn-Ca alloy as the inner coating and then hydroxyapatite (HA) coating as the outer coating was deposited on fluoride coating by pulse reverse current electrodeposition (PRC-HA/MgF 2 ). As a comparative study, the microstructure and corrosion properties of the composite coating with the outer coating fabricated by traditional constant current electrodeposition (TED-HA/MgF 2 ) were also investigated. Scanning electron microscopy (SEM) images of the coatings show that the morphology of PRC-HA/MgF 2 coating is dense and uniform, and presents nano-rod-like structure. Compared with that of TED-HA/MgF 2 , the corrosion current density of Mg alloy coated with PRC-HA/MgF 2 coatings decreases from 5.72 × 10 -5 A/cm 2 to 4.32 × 10 -7 A/cm 2 , and the corrosion resistance increases by almost two orders of magnitude. In immersion tests, samples coated with PRC-HA/MgF 2 coating always show the lowest hydrogen evolution amount, and could induce deposition of the hexagonal structure-apatite on the surface rapidly. The results show that the corrosion resistance and the bioactivity of the coatings have been improved by adopting double-pulse current mode in the process of preparing HA on fluoride coating, and the PRC-HA/MgF 2 coating is worth of further investigation.

Method of protecting the surface of a substrate. [by applying aluminide coating

NASA Technical Reports Server (NTRS)

Gedwill, M. A. (Inventor); Grisaffe, S. J.

1974-01-01

The surface of a metallic base system is initially coated with a metallic alloy layer that is ductile and oxidation resistant. An aluminide coating is then applied to the metallic alloy layer. The chemistry of the metallic alloy layer is such that the oxidation resistance of the subsequently aluminized outermost layer is not seriously degraded.

Investigation of heat-resistant layered coating of Al-Cr-Ni

NASA Astrophysics Data System (ADS)

Shmorgun, V. G.; Trykov, Y. P.; Bogdanov, A. I.; Taube, A. O.

2016-02-01

The paper shows the transformation of the structure and phase composition of the layered coating system Al-Cr-Ni, obtained by the heat treatment of multilayered composite H20N80+AD1, welded by explosion, in the time range 1-300 hours. The cyclic heat resistance of the coating at 1150 ° C is studied.

Apparatus for measurement of critical current in superconductive tapes

DOEpatents

Coulter, J. Yates; DePaula, Raymond

2002-01-01

A cryogenic linear positioner which is primarily used for characterizing coated conductor critical current homogeneity at 75K is disclosed. Additionally, this tool can be used to measure the positional dependence of the coated conductor resistance at room temperature, and the room temperature resistance of the underlying YBCB coating without the overlaying protective cover of silver.

Quality optimization of thermally sprayed coatings produced by the JP-5000 (HVOF) gun using mathematical modeling

NASA Technical Reports Server (NTRS)

Tawfik, Hazem

1994-01-01

Currently, thermal barrier coatings (TBC) of gas-turbine blades and similar applications have centered around the use of zirconia as a protective coating for high thermal applications. The advantages of zirconia include low thermal conductivity and good thermal shock resistance. Thermally sprayed tungsten carbide hardface coatings are used for a wide range of applications spanning both the aerospace and other industrial markets. Major aircraft engine manufacturers and repair facilities use hardface coatings for original engine manufacture (OEM), as well as in the overhaul of critical engine components. The principle function of these coatings is to resist severe wear environments for such wear mechanisms as abrasion, adhesion, fretting, and erosion. The (JP-5000) thermal spray gun is the most advanced in the High Velocity Oxygen Fuel (HVOF) systems. Recently, it has received considerable attention because of its relative low cost and its production of quality coatings that challenge the very successful but yet very expensive Vacuum Plasma Spraying (VPS) system. The quality of thermal spray coatings is enhanced as porosity, oxidation, residual stress, and surface roughness are reduced or minimized. Higher densification, interfacial bonding strength, hardness and wear resistance of coating are desirable features for quality improvement.

Improving the tribological and corrosive properties of MoS2-based coatings by dual-doping and multilayer construction

NASA Astrophysics Data System (ADS)

Shang, Kedong; Zheng, Shaoxian; Ren, Siming; Pu, Jibin; He, Dongqing; Liu, Shuan

2018-04-01

The pure MoS2 coating always performs high friction coefficient and short service life when used in high humidity or after long-time storage in humid atmospheric environment. In this study, the MoS2/Pb-Ti composite and MoS2/Pb-Ti multilayer coatings are deposited to improve the corrosion resistance in 3.5 wt% NaCl solution and tribological performance in high humidity condition. The electrochemical impedance spectra and salt spray test shown that the MoS2/Pb-Ti composite and multilayer coatings can inhibit the permeation of oxygen and other corrosive elements, thus resulting a high corrosion resistance. Furthermore, compared with pure MoS2 coating, the tribological performance of the MoS2/Pb-Ti composite and multilayer coatings is also improved significantly owing to the high mechanical properties and compact structure. Moreover, the heterogenous interfaces in MoS2/Pb-Ti multilayer coating play an important role to improve the corrosion resistance and tribological performance of coatings. Overall, the dual-doping and multilayer construction are promising approaches to design the MoS2 coatings as the environmentally adaptive lubricants.

Pulse electrodeposition of self-lubricating Ni-W/PTFE nanocomposite coatings on mild steel surface

NASA Astrophysics Data System (ADS)

Sangeetha, S.; Kalaignan, G. Paruthimal; Anthuvan, J. Tennis

2015-12-01

Ni-W/PTFE nanocomposite coatings with various contents of PTFE (polytetafluoroethylene) particles were prepared by pulse current (PC) electrodeposition from the Ni-W plating bath containing self lubricant PTFE particles to be co-deposited. Co-deposited PTFE particulates were uniformly distributed in the Ni-W alloy matrix. The coatings were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-ray Diffractometry (XRD) and Vicker's micro hardness tester. Tafel Polarization and electrochemical Impedance methods were used to evaluate the corrosion resistance behaviour of the nanocomposite coatings in 3.5% NaCl solution. It was found that, the Ni-W/PTFE nanocomposite coating has better corrosion resistance than the Ni-W alloy coating. Surface roughness and friction coefficient of the coated samples were assessed by Mitutoyo Surftest SJ-310 (ISO1997) and Scratch tester TR-101-M4 respectively. The contact angle (CA) of a water droplet on the surface of nanocomposite coating was measured by Optical Contact Goniometry (OCA 35). These results indicated that, the addition of PTFE in the Ni-W alloy matrix has resulted moderate microhardness, smooth surface, less friction coefficient, excellent water repellency and enhanced corrosion resistance of the nanocomposite coatings.

Resistive coating for current conductors in cryogenic applications

DOEpatents

Hirayama, Chikara; Wagner, George R.

1982-05-18

This invention relates to a resistive or semiconducting coating for use on current conductors in cryogenic applications. This includes copper-clad superconductor wire, copper wire used for stabilizing superconductor magnets, and for hyperconductors. The coating is a film of cuprous sulfide (Cu.sub.2 S) that has been found not to degrade the properties of the conductors. It is very adherent to the respective conductors and satisfies the mechanical, thermal and electrical requirements of coatings for the conductors.

Performance of Plasma Sprayed Al2O3 Coating in Bio-Simulated Environment

NASA Astrophysics Data System (ADS)

Yıldız, F.; Yetim, A. F.; Alsaran, A.; Çelik, A.

2014-01-01

Alumina coatings deposited on the surface of stainless steel 316L by the method of plasma spraying are studied. Tests for wear and corrosion are preformed in Ringer's solution simulating a human body environment. The structure, microhardness, wear resistance and corrosion resistance of the steel are determined with and without a coating. Deposition of a coating onto the stainless steel is shown to be an effective means for protecting implants from corrosion and wear.

In vitro investigation of biodegradable polymeric coating for corrosion resistance of Mg-6Zn-Ca alloy in simulated body fluid.

PubMed

Gaur, Swati; Singh Raman, R K; Khanna, A S

2014-09-01

A silane-based biodegradable coating was developed and investigated to improve corrosion resistance of an Mg-6Zn-Ca magnesium alloy to delay the biodegradation of the alloy in the physiological environment. Conditions were optimized to develop a stable and uniform hydroxide layer on the alloys surface-known to facilitate silane-substrate adhesion. A composite coating of two silanes, namely, diethylphosphatoethyltriethoxysilane (DEPETES) and bis-[3-(triethoxysilyl) propyl] tetrasulfide (BTESPT), was developed, by the sol-gel route. Corrosion resistance of the coated alloy was characterized in a modified-simulated body fluid (m-SBF), using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The silane coating provided significant and durable corrosion resistance. During the course of this, hydrogen evolution and pH variation, if any, were monitored for both bare and coated alloys. The coating morphology was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) and the cross-linking in the coating was studied using Fourier transform infrared spectroscopy (FTIR). As indicated by X-ray diffraction (XRD) results, an important finding was the presence of hydrated magnesium phosphate on the sample that was subjected to immersion in m-SBF for 216h. Magnesium phosphate is reported to support osteoblast formation and tissue healing. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of Mg on the Microstructure and Corrosion Resistance of the Continuously Hot-Dip Galvanizing Zn-Mg Coating

PubMed Central

Dong, Anping; Li, Baoping; Lu, Yanling; Zhu, Guoliang; Xing, Hui; Shu, Da; Sun, Baode; Wang, Jun

2017-01-01

The microstructure of continuously hot-dip galvanizing Zn-Mg coating was investigated in order to obtain the mechanism of the effects of Mg on the corrosion resistance. In this paper, the vertical section of the Zn-0.20 wt % Al-Mg ternary phase diagram near the Al-low corner was calculated. The results indicates that the phase composition of the Zn-0.20 wt % Al-Mg ternary phase diagram near the Al-low corner is the same as Zn-Mg binary phase diagram, suggesting Al in the Zn-Mg (ZM) coatings mainly concentrates on the interfacial layer between the coating and steel substrate. The microstructure of continuously hot-dip galvanizing ZM coatings with 0.20 wt % Al containing 1.0–3.0 wt % Mg was investigated using tunneling electron microscopy (TEM). The morphology of Zn in the coating changes from bulk to strip and finally to mesh-like, and the MgZn2 changes from rod-like to mesh-like with the Mg content increasing. Al in the ZM coatings mainly segregates at the Fe2Al5 inhibition layer and the Mg added to the Zn bath makes this inhibition layer thinner and uneven. Compared to GI coating, the time of the first red rust appears increases by more than two-fold and expansion rate of red rust reduces by more than four-fold in terms of salt spray experiment. The ZM coating containing 2.0 wt % Mg has the best corrosion resistance. The enhanced corrosion resistance of ZM coatings mainly depends on different corrosion products. PMID:28829393

Effect of Mg on the Microstructure and Corrosion Resistance of the Continuously Hot-Dip Galvanizing Zn-Mg Coating.

PubMed

Dong, Anping; Li, Baoping; Lu, Yanling; Zhu, Guoliang; Xing, Hui; Shu, Da; Sun, Baode; Wang, Jun

2017-08-22

The microstructure of continuously hot-dip galvanizing Zn-Mg coating was investigated in order to obtain the mechanism of the effects of Mg on the corrosion resistance. In this paper, the vertical section of the Zn-0.20 wt % Al-Mg ternary phase diagram near the Al-low corner was calculated. The results indicates that the phase composition of the Zn-0.20 wt % Al-Mg ternary phase diagram near the Al-low corner is the same as Zn-Mg binary phase diagram, suggesting Al in the Zn-Mg (ZM) coatings mainly concentrates on the interfacial layer between the coating and steel substrate. The microstructure of continuously hot-dip galvanizing ZM coatings with 0.20 wt % Al containing 1.0-3.0 wt % Mg was investigated using tunneling electron microscopy (TEM). The morphology of Zn in the coating changes from bulk to strip and finally to mesh-like, and the MgZn₂ changes from rod-like to mesh-like with the Mg content increasing. Al in the ZM coatings mainly segregates at the Fe₂Al₅ inhibition layer and the Mg added to the Zn bath makes this inhibition layer thinner and uneven. Compared to GI coating, the time of the first red rust appears increases by more than two-fold and expansion rate of red rust reduces by more than four-fold in terms of salt spray experiment. The ZM coating containing 2.0 wt % Mg has the best corrosion resistance. The enhanced corrosion resistance of ZM coatings mainly depends on different corrosion products.

Hot corrosion behavior of platinum-modified nickel- and cobalt-based alloys and coatings

NASA Astrophysics Data System (ADS)

Deodeshmukh, Vinay Prakash

High temperature degradation by hot corrosion (650-1000°C) and/or oxidation (>1000°C) can severely reduce the longevity of advanced gas turbine engine components. The protection of high-temperature components against hot corrosion or oxidation is typically conferred by the application of either a diffusion or overlay metallic coating that is able to form a continuous, adherent, and slow-growing oxide scale. There are currently no coatings that provide adequate protection to both hot corrosion and oxidation. Indeed, there is a particular need for such protective coatings because many advanced aero, marine, and industrial gas-turbines operate in both hot corrosion and oxidation regimes in their duty cycle. Recent work at Iowa State University (ISU) has showed that a wide range Pt+Hf-modified gamma'-Ni3Al + gamma-Ni alloy compositions form a very adherent and slow-growing Al 2O3 scale. In fact, the results reported suggest that Pt+Hf-modified gamma' + gamma coatings offer a viable superior alternative to beta-NiAl(Pt)-based coatings. The main thrust of this study was to assess and establish optimum target gamma' + gamma coating compositions for extending the service life of high-temperature gas turbine components exposed to hot corrosion and oxidation conditions. Both high temperature hot-corrosion (HTHC-900°C) and low temperature hot-corrosion (LTHC-705°C) behaviors of the Pt+Hf-modified gamma' + gamma alloys were assessed. The salt used to bring about hot corrosion was Na 2SO4. Quite interestingly, it was found that the HTHC resistance of gamma' + gamma alloys improved with up to about 10 at.% Pt addition, but then decreased significantly with increasing Pt content up to 30 at.% (the maximum level studied); however, under LTHC conditions the resistance of gamma' + gamma alloys improved with increasing Pt content up to 30 at.%. To further improve hot corrosion resistance of Pt+Hf-modified gamma' + gamma alloys, the effects of systematic additions of Cr, Si, and Cr+Si were assessed. The effects pre-oxidation treatments were also studied to further improve the hot corrosion resistance. In addition, high-temperature oxidation behavior of various modified of gamma' + gamma alloys was studied in air at 1150°C under both isothermal and cyclic oxidation conditions. Certain modified versions of gamma' + gamma coating composition(s) exhibited excellent resistance to both hot corrosion and oxidation. Finally, the HTHC and LTHC resistance of novel Pt+Hf-modified gamma' + gamma-based diffusion coatings using a pack cementation process developed at ISU were studied and compared with state-of-the-art commercial coatings. It was found that the Pt+Hf-modified gamma' + gamma coating exhibited superior resistance to both types of hot corrosion with the preoxidation treatment; while, only Pt-modified beta exhibited excellent LTHC resistance with no pre-oxidation treatment. This study also involved evaluating the hot corrosion resistance of various commercially available Pt-modified beta-NiAl diffusion aluminides and CoCrAlY-based overlay coatings for marine gas turbine engine components under both HTHC and LTHC conditions. The Al-Pt-rich beta aluminide exhibited improved resistance to both types of hot corrosion compared to the various Ni-rich beta aluminide and CoCrAlY coatings.

Oxygen plasma treatment and deposition of CN{sub x} on a fluorinated polymer matrix composite for improved erosion resistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muratore, C.; Korenyi-Both, A.; Bultman, J. E.

2007-07-15

The use of polymer matrix composites in aerospace propulsion applications is currently limited by insufficient resistance to erosion by abrasive media. Erosion resistant coatings may provide necessary protection; however, adhesion to many high temperature polymer matrix composite (PMC) materials is poor. A low pressure oxygen plasma treatment process was developed to improve adhesion of CN{sub x} coatings to a carbon reinforced, fluorinated polymer matrix composite. Fullerene-like CN{sub x} was selected as an erosion resistant coating for its high hardness-to-elastic modulus ratio and elastic resilience which were expected to reduce erosion from media incident at different angles (normal or glancing) relativemore » to the surface. In situ x-ray photoelectron spectroscopy was used to evaluate the effect of the plasma treatment on surface chemistry, and electron microscopy was used to identify changes in the surface morphology of the PMC substrate after plasma exposure. The fluorine concentration at the surface was significantly reduced and the carbon fibers were exposed after plasma treatment. CN{sub x} coatings were then deposited on oxygen treated PMC substrates. Qualitative tests demonstrated that plasma treatment improved coating adhesion resulting in an erosion resistance improvement of a factor of 2 compared to untreated coated composite substrates. The combination of PMC pretreatment and coating with CN{sub x} reduced the erosion rate by an order of magnitude for normally incident particles.« less

Morphology of powders of tungsten carbide used in wear-resistant coatings and deposition on the PDC drill bits

NASA Astrophysics Data System (ADS)

Zakharova, E. S.; Markova, I. Yu; Maslov, A. L.; Polushin, N. I.; Laptev, A. I.

2017-05-01

Modern drill bits have high abrasive wear in the area of contact with the rock and removed sludge. Currently, these bits have a protective layer on the bit body, which consists of a metal matrix with inclusions of carbide particles. The research matrix of this coating and the wear-resistant particles is a prerequisite in the design and production of drill bits. In this work, complex investigation was made for various carbide powders of the grades Relit (tungsten carbide produced by Ltd “ROSNAMIS”) which are used as wear-resistant particles in the coating of the drill bit body. The morphology and phase composition of the chosen powders as well as the influence of a particle shape on prospects of their application in wear-resistance coating presented in this work.

Effects of membrane composition on release of model hydrophilic compound from osmotic delivery systems.

PubMed

Ozdemir, N; Ozalp, Y; Ozkan, Y

2000-01-01

In this study, the effects of surface-active agents in different types and concentrations, added into the coating solution, on release of model hydrophilic compound have been examined. For this purpose, the tablets, prepared with the use of methylene blue as a model substance, were coated by spray coating technique with cellulose acetate solution containing polyethylene glycol 400 as a plasticizer. In addition, cetylpyridinium chloride as cationic surface-active agent and sodium lauryl sulphate as anionic surface-active agent were added into coating solution in different concentrations. After creating a delivery orifice by a microdrill on the tablets, release of model hydrophilic compound was tested by the USP paddle method. The data obtained were evaluated according to the different kinetics and the mechanism of release from the preparations was examined. The surface properties of the coating material were investigated by scanning electron microscope taken before and after the contact with medium fluid, as well as the mechanical properties by tensile tests. In conclusion, it has been found that the cationic surface active agent, cetylpyridinium chloride reduced the lag time, observed during the release of model hydrophilic compound, as a result of its enhancing effect on wettability of tablets by reducing the contact angle between the medium fluid and the coating material. On the other hand, the anionic surface active agent, sodium lauryl sulphate has been inactivated possibly due to the interaction with model hydrophilic compound that has cationic properties and/or substances contained in membrane composition; thus, the lag time has not decreased and furthermore, a significant decrease in the delivery rate of model hydrophilic compound has been observed.

Versatile device for in-situ discharge cleaning and multiple coatings of long, small diameter tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershcovitch, A.; Blaskiewicz, M.; Brennan, J.M.

Electron clouds, which can limit machine performance, have been observed in many accelerators including RHIC at BNL. Additional concern for the RHIC machine, whose vacuum chamber is made from relatively high resistivity 316LN stainless steel, is high wall resistivity that can result in unacceptably high ohmic heating for superconducting magnets. The high resistivity can be addressed with a copper (Cu) coating; a reduction in the secondary electron yield can be achieved with a TiN or amorphous carbon (a-C) coating. Applying such coatings in an already constructed machine is rather challenging. We have been developing a robotic plasma deposition technique formore » in-situ coating of long, small diameter tubes. The technique entails fabricating a device comprising of staged magnetrons mounted on a mobile mole for deposition of about 5 ?m of Cu followed by about 0.1 ?m of a-C. As a first step, a 15-cm Cu cathode magnetron was designed, fabricated, and 30-cm long samples of the RHIC pipe have been coated with 2 ?m to 5.6 ?m of copper. Deposition rates of up to 92 A/sec with an average coating rate of 30 A/sec were measured. Effects on RF resistivity is also to be measured.« less

Robust and underwater superoleophobic coating with excellent corrosion and biofouling resistance in harsh environments

NASA Astrophysics Data System (ADS)

Su, Mingji; Liu, Yong; Zhang, Yuhong; Wang, Zhiguo; Li, Yulin; He, Peixin

2018-04-01

Underwater superoleophobic surfaces are based on the surface with micro-/nanoscale roughness and hydration layer. But the self-cleaning surfaces are usually mechanically weak and will lose their underwater superoleophobicity when the surfaces are corroded or damaged. In this paper, to overcome these problems, the robust underwater superoleophobic coating (HN/ER-coating) has been fabricated successfully through MPS (methacryloxy propyl trimethoxyl silane)-SiO2/PNIPAM (N-isopropylacryamide) hybrid nanoparticles and epoxy resin (ER) via a simple solution-casting method. The SiO2/PNIPAM hybrid nanoparticles can enhance multiscale roughness and excellent abrasion-resistant property, and the epoxy resin can be used as an interlayer between hybrid nanoparticles and substrates to promote the robustness and corrosion resistance of the coating. The obtained coatings have excellent underwater superoleophobicity, and exhibit highly stability in harsh environments (including acid-base, strong ionic strength, mechanical abrasion). Moreover, this coating can provide protective effect on the substrate in corrosive solution, and may also resist bacterial attachment and subsequent biofilm formation because of the presence of high density PNIPAM polymers. Herein, the developed underwater superoleophobic coating can be applied as an effective platform for the applications in underwater instruments, underwater oil transport, marine oil platform and ships.

Antibacterial effects, biocompatibility and electrochemical behavior of zinc incorporated niobium oxide coating on 316L SS for biomedical applications

NASA Astrophysics Data System (ADS)

Pradeep PremKumar, K.; Duraipandy, N.; Manikantan Syamala, Kiran; Rajendran, N.

2018-01-01

In the present study, Nb2O5 (NZ0) composite coatings with various concentrations of zinc (NZ2, NZ4 & NZ6) are produced on 316L SS by sol-gel method with the aim of improving its antibacterial activity, bone formability and corrosion resistance properties. This work studied the surface characterization of NZ0, NZ2, NZ4 & NZ6 coated 316L SS by ATR-FTIR, XRD, HR-SEM with EDAX. The synthesized coatings were different in the morphological aspects, NZ0 shows mesoporous morphology whereas irregular cluster like morphology was observed for the zinc incorporated coatings. The chemical composition of the NZ0 and NZ4 composite coatings were studied by XPS and the results revealed that the zinc exist as ZnO and Nb as Nb2O5 in the coatings. The increase in the concentration of zinc in Nb2O5 increases the hydrophilic nature identified by water contact angle studies. The potentiodynamic polarization studies in simulated body fluid reveals the increase in polarization resistance with decrease in current density (icorr) and electrochemical impedance spectroscopic studies with increase in charge transfer resistance (Rct) and double layer capacitance (Qdl) were observed for NZ4 coated 316L SS. The inhibition of Staphylococcus aureus and Escherichia coli bacteria were identified for NZ4 coated 316L SS by bacterial viability studies. The NZ4 coated 316L SS showed better Osseo-integration by spreading the MG 63 osteoblast cells. The study results imply that zinc incorporated Nb2O5 (NZ4) composite coating exhibits antibacterial activity and also enhance the corrosion resistance and biocompatibility of the 316L SS.

Plasma spray processing of TiC-based coatings for sliding wear resistance

NASA Astrophysics Data System (ADS)

Mohanty, Mahesh

Titanium carbide-reinforced metallic coatings, produced by plasma spraying, can be used for sliding wear resistant applications. The sliding wear properties of such coatings are governed to a large extent by the strength, structure and stability of the bond interface between the carbide and the metallic phases. In the present investigation, the microstructure and sliding wear properties of plasma sprayed metal-bonded TiC coatings containing up to 90 v/o carbide have been studied. It was shown that alloying of the metallic phase improved carbide retention in TiC cermets due to better interface bonding, and increased wear resistance and lowered sliding coefficient of friction. TiC-based coatings were produced from both physically blended and synthesized feed powders. It was observed that the precursor TiC-based powder morphology and structure greatly affected the plasma sprayed coating microstructures and the resultant physical and mechanical characteristics. Physical blending of powders induced segregation during spraying, leading to somewhat lower deposit efficiencies and coating uniformity, while synthesized and alloyed titanium carbide/metal composite powders reduced problems of segregation and reactions associated with plasma spraying of physically blended powders where the TiC was in direct contact with the plasma jet. To understand oxidation effects of the environment, Ti and TiC-based coatings were produced under low pressure (VPS), air plasma (APS) and shrouded plasma sprayed conditions. APS Ti and TiC-based powders with reactive matrices suffered severe oxidation decomposition during flight, leading to poor deposition efficiencies and oxidized microstructures. High particle temperatures and cold air plasma spraying. Coating oxidation due to reactions of the particles with the surrounding air during spraying reduced coating hardness and wear resistance. TiC-with Ti or Ti-alloy matrix coatings with the highest hardness, density and wear resistance was achieved by spraying under vacuum plasma spray conditions. VPS coating microstructures of synthesized 40, 60 and 80 v/o TiC in Ti10Ni10Cr5Al and 80 v/o TiC in Fe30Cr alloy matrices exhibited fine and uniform distributions of spheroidal carbides. High volume fraction carbides were also obtained with no segregation effects. It was also shown that coatings produced from mechanically blended powders of 50, 70 and 90 vol. % TiC and commercially pure (C.P.) Ti, using low pressure plasma spray process (VPS), had densities >98% and were well bonded to steel, aluminum alloy or titanium alloy substrates. Reductions in jet oxygen contents by the use of an inert gas shroud enabled Ti and TiC-based coatings to be produced which were cleaner and denser than air plasma sprayed and comparable to vacuum plasma sprayed coatings. Direct oxygen concentration measurements in shrouded plasma jets made using an enthalpy probe and a gas analyzer also showed significant reductions in the entrainment of atmospheric oxygen. VPS and shrouded plasma spraying minimized carbide-matrix interface oxidation and improved coating wear resistance. The sliding wear resistance of synthesized coatings was very high and comparable with standard HVOF sprayed WC/Co and Crsb3Csb2/NiCr coatings. Shrouded plasma spray deposits of Crsb3Csb2/NiCr also performed much better than similar air plasma sprayed coatings, as result of reduced oxidation.

Preparation and corrosion resistance of electroless Ni-P/SiC functionally gradient coatings on AZ91D magnesium alloy

NASA Astrophysics Data System (ADS)

Wang, Hui-Long; Liu, Ling-Yun; Dou, Yong; Zhang, Wen-Zhu; Jiang, Wen-Feng

2013-12-01

In this paper, the protective electroless Ni-P/SiC gradient coatings on AZ91D magnesium alloy substrate were successfully prepared. The prepared Ni-P/SiC gradient coatings were characterized for its microstructure, morphology, microhardness and adhesion to the substrate. The deposition reaction kinetics was investigated and an empirical rate equation for electroless Ni-P/SiC plating on AZ91D magnesium alloy was developed. The anticorrosion properties of the Ni-P/SiC gradient coatings in 3.5 wt.% NaCl solution were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies. The potentiodynamic polarization measurements revealed that the SiC concentration in the bath and heat treatment can influence the corrosion protection performance of electroless deposited Ni-P/SiC gradient coatings. EIS studies indicated that higher charge transfer resistance and slightly lower capacitance values were obtained for Ni-P/SiC gradient coatings compared to Ni-P coatings. The corrosion resistance of the Ni-P/SiC gradient coatings increases initially and decreases afterwards with the sustained increasing of immersion time in the aggressive medium. The electroless Ni-P/SiC gradient coatings can afford better corrosion protection for magnesium alloy substrate compared with Ni-P coatings.

Effect of layer thickness on the properties of nickel thermal sprayed steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurisna, Zuhri, E-mail: zuhri-nurisna@yahoo.co.id; Triyono,, E-mail: triyonomesin@uns.ac.id; Muhayat, Nurul, E-mail: nurulmuhayat@staff.uns.ac.id

Thermal arc spray nickel coating is widely used for decorative and functional applications, by improving corrosion resistance, wear resistance, heat resistence or by modifying other properties of the coated materials. There are several properties have been studied. Layer thickness of nickel thermal sprayed steel may be make harder the substrate surface. In this study, the effect of layer thickness of nickel thermal sprayed steel has been investigated. The rectangular substrate specimens were coated by Ni–5 wt.% Al using wire arc spray method. The thickness of coating layers were in range from 0.4 to 1.0 mm. Different thickness of coating layers weremore » conducted to investigate their effect on hardness and morphology. The coating layer was examined by using microvickers and scanning electron microscope with EDX attachment. Generally, the hardness at the interface increased with increasing thickness of coating layers for all specimens due to higher heat input during spraying process. Morphology analysis result that during spraying process aluminum would react with surrounding oxygen and form aluminum oxide at outer surface of splat. Moreover, porosity was formed in coating layers. However, presence porosity is not related to thickness of coating material. The thicker coating layer resulted highesr of hardness and bond strength.« less

Enhanced corrosion resistance of strontium hydroxyapatite coating on electron beam treated surgical grade stainless steel

NASA Astrophysics Data System (ADS)

Gopi, D.; Rajeswari, D.; Ramya, S.; Sekar, M.; R, Pramod; Dwivedi, Jishnu; Kavitha, L.; Ramaseshan, R.

2013-12-01

The surface of 316L stainless steel (316L SS) is irradiated by high energy low current DC electron beam (HELCDEB) with energy of 500 keV and beam current of 1.5 mA followed by the electrodeposition of strontium hydroxyapatite (Sr-HAp) to enhance its corrosion resistance in physiological fluid. The coatings were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and High resolution scanning electron microscopy (HRSEM). The Sr-HAp coating on HELCDEB treated 316L SS exhibits micro-flower structure. Electrochemical results show that the Sr-HAp coating on HELCDEB treated 316L SS possesses maximum corrosion resistance in Ringer's solution.

Applications of Laser Cladded WC-Based Wear Resistant Coatings

NASA Astrophysics Data System (ADS)

Verwimp, Jo; Rombouts, Marleen; Geerinckx, Eric; Motmans, Filip

Laser cladding is an additive process wherein a laser source is used to melt metal-based powder or wire on to a metal substrate. The technique is frequently used to produce wear resistant coatings consisting of a metal matrix and a ceramic strengthening phase. In this study mixtures of nickel based powders and various amounts of tungsten carbides have been used as feedstock for laser cladding on a range of steel substrates and for different applications. Crack-free low porosity coatings with a thickness of about 1 mm and carbide concentrations up to 50 vol% have been produced. The evaluation of the wear resistance of the different coatings is performed on lab scale or in the application itself.

Improving the Fatigue Crack Propagation Resistance and Damage Tolerance of 2524-T3 Alloy with Amorphous Electroless Ni-P Coating

NASA Astrophysics Data System (ADS)

Chen, Lai; Zeng, Diping; Liu, Zhiyi; Bai, Song; Li, Junlin

2018-02-01

The surface microhardness, as well as the fatigue crack propagation (FCP) resistance of 2524-T3 alloy, is improved by producing a 20-μm-thick amorphous electroless Ni-12% P coating on its surface. Compared to the substrate, this deposited EN coating possesses higher strength properties and exhibits a greater ability of accommodating the plastic deformation at the fatigue crack tip, thereby remarkably improving the FCP resistance in near-threshold and early Paris regimes. Regardless of the similar FCP rates in Paris regime (Δ K ≥ 16.2 MPa m0.5), the coated sample exhibits extended Paris regime and enhanced damage tolerance.

Enhanced mechanical properties and increased corrosion resistance of a biodegradable magnesium alloy by plasma electrolytic oxidation (PEO).

PubMed

White, Leon; Koo, Youngmi; Neralla, Sudheer; Sankar, Jagannathan; Yun, Yeoheung

2016-06-01

We report the enhanced mechanical properties of AZ31 magnesium alloys by plasma electrolytic oxidation (PEO) coating in NaOH, Na 2 SiO 3 , KF and NaH 2 PO 4 ·2H 2 O containing electrolytes. Mechanical properties including wear resistance, surface hardness and elastic modulus were increased for PEO-coated AZ31 Mg alloys (PEO-AZ31). DC polarization in Hank's solution indicating that the corrosion resistance significantly increased for PEO-coating in KF-contained electrolyte. Based on these results, the PEO coating method shows promising potential for use in biodegradable implant applications where tunable corrosion and mechanical properties are needed.

Development of Titanium Dioxide (TiO2 ) Nanocoatings on Food Contact Surfaces and Method to Evaluate Their Durability and Photocatalytic Bactericidal Property.

PubMed

Yemmireddy, Veerachandra K; Farrell, Glenn D; Hung, Yen-Con

2015-08-01

Titanium dioxide (TiO2 ) is a well-known photocatalyst for its excellent bactericidal property under UVA light. The purpose of this study was to develop physically stable TiO2 coatings on food contact surfaces using different binding agents and develop methods to evaluate their durability and microbicidal property. Several types of organic and inorganic binders such as polyvinyl alcohol, polyethylene glycol, polyurethane, polycrylic, sodium and potassium silicates, shellac resin, and other commercial binders were used at 1:1 to 1:16 nanoparticle to binder weight ratios to develop a formulation for TiO2 coating on stainless steel surfaces. Among the tested binders, polyurethane, polycrylic, and shellac resin were found to be physically more stable when used in TiO2 coating at 1:4 to 1:16 weight ratio. The physical stability of TiO2 coatings was determined using adhesion strength and scratch hardness tests by following standard ASTM procedures. Further, wear resistance of the coatings was evaluated based on a simulated cleaning procedure used in food processing environments. TiO2 coating with polyurethane at a 1:8 nanoparticle to binder weight ratio showed the highest scratch hardness (1.08 GPa) followed by coating with polycrylic (0.68 GPa) and shellac (0.14 GPa) binders. Three different techniques, namely direct spreading, glass cover-slip, and indented coupon were compared to determine the photocatalytic bactericidal property of TiO2 coatings against Escherichia coli 0157:H7 at 2 mW/cm(2) UVA light intensity. Under the tested conditions, the indented coupon technique was found to be the most appropriate method to determine the bactericidal property of TiO2 coatings and showed a reduction of 3.5 log CFU/cm(2) in 2 h. © 2015 Institute of Food Technologists®

Preparation of Highly Conductive Yarns by an Optimized Impregnation Process

NASA Astrophysics Data System (ADS)

Amba Sankar, K. N.; Mohanta, Kallol

2017-12-01

We report the development of the electrical conductivity in textile yarns through impregnation and post-treatment of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The conductive polymer is deposited on fibers, which fills the gap space within the hierarchical structure of the yarns. Organic nonpolar solvents act as reducing agent to increase the density of PEDOT moieties on the yarns, galvanizing increment in conductivity values. Post-treatment by ethylene glycol transforms the resonance configuration of the conductive moieties of conjugated polymer, which helps in further enhancement of electrical conductivity of the yarns. We have optimized the method in terms of loading and conformal change of the polymer to have a lesser resistance of the coated conductive yarns. The minimum resistance achieved has a value of 77 Ωcm-1. This technique of developing conductivity in conventional yarns enables retaining the flexibility of yarns and feeling of softness which would find suitable applications for wearable electronics.

Cyclodextrins: A Weapon in the Fight Against Antimicrobial Resistance

NASA Astrophysics Data System (ADS)

Wong, Chew Ee; Dolzhenko, Anton V.; Lee, Sui Mae; Young, David James

Antimicrobial resistance poses one of the most serious global challenges of our age. Cyclodextrins (CDs) are widely utilized excipients in formulations because of their solubilizing properties, low toxicity, and low inflammatory response. This review summarizes recent investigations of antimicrobial agents involving CDs and CD-based antimicrobial materials. CDs have been employed for antimicrobial applications either through formation of inclusion complexes or by chemical modification of their hydroxyl groups to tailor pharmaceutically active compounds. Applications of these CD inclusion complexes include drug delivery, antimicrobial coatings on materials (e.g., biomedical devices and implants) and antimicrobial dressings that help to prevent wound infections. There are relatively limited studies of chemically modified CDs with antimicrobial activity. The mechanism of action of antimicrobial CD inclusion complexes and derivatives needs further elucidation, but activity of CDs and their derivatives is often associated with their interaction with bacterial cell membranes.

Preparation of Highly Conductive Yarns by an Optimized Impregnation Process

NASA Astrophysics Data System (ADS)

Amba Sankar, K. N.; Mohanta, Kallol

2018-03-01

We report the development of the electrical conductivity in textile yarns through impregnation and post-treatment of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The conductive polymer is deposited on fibers, which fills the gap space within the hierarchical structure of the yarns. Organic nonpolar solvents act as reducing agent to increase the density of PEDOT moieties on the yarns, galvanizing increment in conductivity values. Post-treatment by ethylene glycol transforms the resonance configuration of the conductive moieties of conjugated polymer, which helps in further enhancement of electrical conductivity of the yarns. We have optimized the method in terms of loading and conformal change of the polymer to have a lesser resistance of the coated conductive yarns. The minimum resistance achieved has a value of 77 Ωcm-1. This technique of developing conductivity in conventional yarns enables retaining the flexibility of yarns and feeling of softness which would find suitable␣applications for wearable electronics.

Corrosion Performance of Nano-ZrO₂ Modified Coatings in Hot Mixed Acid Solutions.

PubMed

Xu, Wenhua; Wang, Zhenyu; Han, En-Hou; Wang, Shuai; Liu, Qian

2018-06-01

A nano-ZrO₂ modified coating system was prepared by incorporation of nano-ZrO₂ concentrates into phenolic-epoxy resin. The corrosion performance of the coatings was evaluated in hot mixed acid solution, using electrochemical methods combined with surface characterization, and the effects of nano-ZrO₂ content were specially focused on. The results showed that 1% and 3% nano-ZrO₂ addition enhanced the corrosion resistance of the coatings, while 5% nano-ZrO₂ addition declined it. The coating with 3% nano-ZrO₂ presented the minimum amount of species diffusion, the lowest average roughness (5.94 nm), and the highest C/O ratio (4.55) and coating resistance, and it demonstrated the best corrosion performance among the coating specimens.

Oxidation resistant slurry coating for carbon-based materials

NASA Technical Reports Server (NTRS)

Smialek, J. L.; Rybicki, G. C. (Inventor)

1985-01-01

An oxidation resistant coating is produced on carbon-base materials, and the same processing step effects an infiltration of the substrate with silicon containing material. The process comprises making a slurry of nickel and silicon powders in a nitrocellulose lacquer, spraying onto the graphite or carbon-carbon substrate, and sintering in vacuum to form a fused coating that wets and covers the surface as well as penetrates into the pores of the substrate. Optimum wetting and infiltration occurs in the range of Ni-60 w/o Si to Ni-90 w/o Si with deposited thicknesses of 25-100 mg/sq. cm. Sintering temperatures of about 1200 C to about 1400 C are used, depending on the melting point of the specific coating composition. The sintered coating results in Ni-Si intermetallic phases and SiC, both of which are highly oxidation resistant.

Dissipated energy as a design parameter of coated conductors for their use in resistive fault current limiters

NASA Astrophysics Data System (ADS)

Schacherer, C.; Kudymow, A.; Noe, M.

2008-02-01

Coated conductors are suitable for many power applications like motors, magnets and superconducting fault current limiters (SCFCLs). For their use in resistive SCFCLs main requirements are quench stability and resistance development above Tc. Several coated conductors are available with different kinds of stabilization like thickness or material of cap-layer and additional stabilization. The stabilization can vary and has a great influence on the quench stability and quench behaviour of a coated conductor. Thus, for the dimensioning of a superconducting current limiting element there is a need of reliable and universal design parameters. This paper presents experimental quench test results on several coated conductor types with different stabilization and geometry. The test results show that the dissipated energy during a quench is a very useful parameter for the SCFCL design.

Conformal chemically resistant coatings for microflow devices

DOEpatents

Folta, James A.; Zdeblick, Mark

2003-05-13

A process for coating the inside surfaces of silicon microflow devices, such as electrophoresis microchannels, with a low-stress, conformal (uniform) silicon nitride film which has the ability to uniformly coat deeply-recessed cavities with, for example, aspect ratios of up to 40:1 or higher. The silicon nitride coating allows extended exposure to caustic solutions. The coating enables a microflow device fabricated in silicon to be resistant to all classes of chemicals: acids, bases, and solvents. The process involves low-pressure (vacuum) chemical vapor deposition. The ultra-low-stress silicon nitride deposition process allows 1-2 .mu.m thick films without cracks, and so enables extended chemical protection of a silicon microflow device against caustics for up to 1 year. Tests have demonstrated the resistance of the films to caustic solutions at both ambient and elevated temperatures to 65.degree. C.

Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

DOEpatents

Chow, Robert; Loomis, Gary E.; Thomas, Ian M.

1999-01-01

Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (.about.1.10-1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm.

Effect of Sn4+ Additives on the Microstructure and Corrosion Resistance of Anodic Coating Formed on AZ31 Magnesium Alloy in Alkaline Solution

NASA Astrophysics Data System (ADS)

Salman, S. A.; Kuroda, K.; Saito, N.; Okido, M.

Magnesium is the lightest structural metal with high specific strength and good mechanical properties. However, poor corrosion resistance limits its widespread use in many applications. Magnesium is usually treated with Chromate conversion coatings. However, due to changing environmental regulations and pollution prevention requirements, a significant push exists to find new, alternative for poisonous Cr6+. Therefore, we aim to improve corrosion resistance of anodic coatings on AZ31 alloys using low cost non-chromate electrolyte. Anodizing was carried out in alkaline solutions with tin additives. The effect of tin additives on the coating film was characterized by SEM and XRD. The corrosion resistance was evaluated using anodic and cathodic polarizations and electrochemical impedance spectroscopy (EIS). Corrosion resistance property was improved with tin additives and the best anti-corrosion property was obtained with addition of 0.03 M Na2SnO3.3H2O to anodizing solution.

Preparing high-adhesion silver coating on APTMS modified polyethylene with excellent anti-bacterial performance

NASA Astrophysics Data System (ADS)

Li, Wenfei; Chen, Yunxiang; Wu, Song; Zhang, Jian; Wang, Hao; Zeng, Dawen; Xie, Changsheng

2018-04-01

Silver coating as a broad-spectrum antimicrobial agent was considered to alleviate the inflammation caused by intrauterine device (IUD) in endometrium. In this work, to avoid the damage of silver coating and ensure its antibacterial properties, 3-aminopropyltrimethoxysilane (APTMS) was introduced to modify the polyethylene (PE) substrate for the purpose of improving the adhesion of the silver coating. From the 90° peel test, it could be found that the adhesive strength of silver coating on the APTMS modified PE substrate was nearly 23 times stronger than the silver coating on substrate without surface modification. The dramatically enhanced adhesive strength could be attributed to the formation of continuous chemical bonds between the silver coatings and substrates after surface modification, which had been confirmed by the XPS. Moreover, the standard antibacterial test revealed that the silver coated samples against Staphylococcus aureus (S. aureus) exhibit excellent antibacterial efficacy. Considering the largely enhanced adhesion and the effective antibacterial property, it is reasonable to believe that the silver coating could be considered as a potential candidate for the antibacterial agent in IUD.

The effect of irradiation process on the optical fiber coating

NASA Astrophysics Data System (ADS)

Wang, Zeyu; Xiao, Chun; Rong, Liang; Ji, Wei

2018-03-01

Protective fiber coating decides the mechanical strength of an optical fiber as well as its resistance against the influence of environment, especially in some special areas like irradiation atmospheres. According to the experiment in this paper, it was found that the tensile force and peeling force of resistant radiation optical fiber was improved because of the special optical fiber coating.

Research and Development on Advanced Graphite Materials. Volume 34- Oxidation-Resistance Coatings for Graphite

DTIC Science & Technology

1963-06-01

RESISTANCE COATINGS "FOR GRAPHITE TECHNICAL DOCUMENTARY REPORT NO. WADD TR 61-72, Volume XXXIV ELECT" June 1963 D-I’C a AUý 0 219940 -14 0u c 94Air Force... coating on\\ Ex.: C (substrate’) + SiC1 R. SiC + graphite, + 4HCI (gas) oo flush Z000C 2 277I I I Deposition of coatings by plasma spraying also has...materials to withstand high tem- peratures has led to the investigation of the plasma torch as a means for 3 depositing protective coatings

Influence of bath PH value on microstructure and corrosion resistance of phosphate chemical conversion coating on sintered Nd-Fe-B permanent magnets

NASA Astrophysics Data System (ADS)

Ding, Xia; Xue, Long-fei; Wang, Xiu-chun; Ding, Kai-hong; Cui, Sheng-li; Sun, Yong-cong; Li, Mu-sen

2016-10-01

The effect of bath PH value on formation, microstructure and corrosion resistance of the phosphate chemical conversion (PCC) coatings as well as the effect on the magnetic property of the magnets is investigated in this paper. The results show that the coating mass and thickness increase with the decrease of the bath PH value. Scanning electron microscopy observation demonstrates that the PCC coatings are in a blocky structure with different grain size. Transmission electron microscope and X-ray diffractometer tests reveal the coatings are polycomponent and are mainly composed of neodymium phosphate hydrate and praseodymium phosphate hydrate. The electrochemical analysis and static immersion corrosion test show the corrosion resistance of the PCC coatings prepared at bath PH value of 0.52 is worst. Afterwards the corrosion resistance increases first and then decreases with the increasing of the bath PH values. The magnetic properties of all the samples with PCC treatment are decreased. The biggest loss is occurred when the bath PH value is 0.52. Taken together, the optimum PH range of 1.00-1.50 for the phosphate solution has been determined.

Oxidation Resistant, Cr Retaining, Electrically Conductive Coatings on Metallic Alloys for SOFC Interconnects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vladimir Gorokhovsky

2008-03-31

This report describes significant results from an on-going, collaborative effort to enable the use of inexpensive metallic alloys as interconnects in planar solid oxide fuel cells (SOFCs) through the use of advanced coating technologies. Arcomac Surface Engineering, LLC, under the leadership of Dr. Vladimir Gorokhovsky, is investigating filtered-arc and filtered-arc plasma-assisted hybrid coating deposition technologies to promote oxidation resistance, eliminate Cr volatility, and stabilize the electrical conductivity of both standard and specialty steel alloys of interest for SOFC metallic interconnect (IC) applications. Arcomac has successfully developed technologies and processes to deposit coatings with excellent adhesion, which have demonstrated a substantialmore » increase in high temperature oxidation resistance, stabilization of low Area Specific Resistance values and significantly decrease Cr volatility. An extensive matrix of deposition processes, coating compositions and architectures was evaluated. Technical performance of coated and uncoated sample coupons during exposures to SOFC interconnect-relevant conditions is discussed, and promising future directions are considered. Cost analyses have been prepared based on assessment of plasma processing parameters, which demonstrate the feasibility of the proposed surface engineering process for SOFC metallic IC applications.« less

Electro-codeposition of Ni-SiO2 nanocomposite coatings from deep eutectic solvent with improved corrosion resistance

NASA Astrophysics Data System (ADS)

Li, Ruiqian; Hou, Yuanyuan; Liang, Jun

2016-03-01

Electro-codeposition of nano-sized SiO2 particles into the metal matrix in aqueous solution is generally difficult. In this paper, the nano-sized SiO2 particles were successfully codeposited in the Ni matrix from a choline chloride (ChCl)/ethylene glycol (EG) based deep eutectic solvent (DES) by pulse electro-codeposition. The effects of nano-sized SiO2 particles on electrochemical behaviour of Ni(II) were investigated. The microstructure, composition and corrosion resistance of pure Ni and Ni-SiO2 nanocomposite coatings were explored. Results showed that the SiO2 nanoparticles exhibited excellent dispersion stability in ChCl:2EG DES without any stabilizing additives and the presence of SiO2 nanoparticles have significant effects on the nucleation mechanism of Ni. The maximum content of SiO2 nanoparticles in composite coatings can achieve 4.69 wt.%, which closes to the level of co-deposition micro-sized SiO2 particles from aqueous solution. The Ni-SiO2 nanocomposite coatings exhibit much better corrosion resistance than pure Ni coating, and the corrosion resistance performance increases with increasing SiO2 content in the composite coatings.

Colon targeted delivery systems of metronidazole based on osmotic technology: development and evaluation.

PubMed

Kumar, Pramod; Singh, Sanjay; Mishra, Brahmeshwar

2008-09-01

Colon targeted delivery systems of metronidazole (MTZ) based on osmotic technology were developed. The developed systems consisted of osmotic core (drug, osmotic agent and wicking agent), coated with semipermeable membrane (SPM) containing guar gum as pore former, coated core were then further coated with enteric coating to protect the system from acidic environment of stomach. The effect of various formulation variables namely the level of wicking agent (sodium lauryl sulphate), osmotic agent in the osmotic core, the level of pore former (guar gum) in SPM, and the thickness of SPM, were studied on physical parameters and drug release characteristics of developed formulations. MTZ release was inversely proportional to SPM thickness, but directly related to the level of pore former, wicking agent and osmotic agent. On the other hand burst strength of the exhausted shells was decreased with the increase in level of pore former in the membrane but increased with the increase in the thickness of SPM. The drug release from the developed formulations was independent of pH, and agitation intensity, but dependent on the osmotic pressure of the release media. The thickness of enteric coating could prevent formation of delivery pores before contact with simulated colonic fluid, but had no effect on drug release. Result of SEM studies showed the formation of in-situ delivery pores in the membrane from where the drug release occurred, and the number of pores formed were directly related to the initial level of pore former (guar gum) in SPM. The manufacturing procedure was found to be reproducible and formulations were found to be stable during 3 months of accelerated stability studies.

Internal coating of zirconia restoration with silica-based ceramic improves bonding of resin cement to dental zirconia ceramic.

PubMed

Kitayama, Shuzo; Nikaido, Toru; Ikeda, Masaomi; Alireza, Sadr; Miura, Hiroyuki; Tagami, Junji

2010-01-01

Resin bonding to zirconia ceramic cannot be established by standard methods that are utilized for conventional silica-based dental ceramics. This study was aimed to examine the tensile bond strength of resin cement to zirconia ceramic using a new laboratory technique. Sixty-four zirconia ceramic specimens were air-abraded using Al2O3 particles and divided into two groups; the control group with no pretreatment (Control), and the group pretreated using the internal coating technique (INT), in which the surface of the zirconia specimens were thinly coated by fusing silica-based ceramic and air-abraded in the same manner. The specimens in each group were further divided into two subgroups according to the silane coupling agents applied; a mixture of dentin primer/silane coupling agent (Clearfil SE Bond Primer/Porcelain Bond Activator) or a newly developed single-component silane coupling agent (Clearfil Ceramic Primer). After bonding with dual-cured resin cement (Panavia F 2.0), they were stored in water for 24 h and half of them were additionally subjected to thermal cycling. The tensile bond strengths were tested using a universal testing machine. ANOVAs revealed significant influence of ceramic surface pretreatment (p<0.001), silane coupling agent (p<0.001) and thermal cycling (p<0.001); the INT coating technique significantly increased the bond strengths of resin cement to zirconia ceramic, whereas thermal cycling significantly decreased the bond strengths. The use of a single-component silane coupling agent demonstrated significantly higher bond strengths than that of a mixture of dentin primer/silane coupling agent. The internal coating of zirconia dental restorations with silica-based ceramic followed by silanization may be indicated in order to achieve better bonding for the clinical success.

All-in-one theranostic nanoagent for head and neck cancer treatment

NASA Astrophysics Data System (ADS)

Dreifuss, Tamar; Davidi, Erez Shmuel; Motiei, Menachem; Barnoy, Eran; Bragilovski, Dimitri; Lubimov, Leon; Kindler, Marc Jose Jonathan; Popovtzer, Aron; Popovtzer, Rachela

2018-02-01

Despite the significant improvement in the treatment paradigm of head and neck cancer, owing to advanced radiation techniques in combination with chemotherapy, resistance of tumors remains a critical problem, leading to poor outcomes and negative prognosis. In addition, chemotherapeutic agents result in severe systemic toxicity due to nonselective damaging of normal cells. Recently, nanoparticle-based approaches have gained broad attention for improving both radiation therapy and chemotherapy. In this study, we present a dual effect nanoplatform, consists of gold nanoparticles coated with glucose and cisplatin (CG-GNPs), which simultaneously acts as a radiosensitizer and as a carrier which specifically deliver cisplatin to head and neck tumor. Our CG-GNPs showed significant penetration into tumor cells and similar cellular toxicity as cisplatin alone. Moreover, in combination with radiation treatment, CG-GNPs led to greater tumor reduction than that of free cisplatin with radiation. Furthermore, our CG-GNPs also demonstrated highly efficient imaging capabilities, as they act as ideal tumor-targeted CT contrast agent. Therefore, this single nano-formulation is a promising theranostic agent that has the potential to increase the antitumor effect and allow imaging guided therapy.

Engineered design of mesoporous silica nanoparticles to deliver doxorubicin and P-glycoprotein siRNA to overcome drug resistance in a cancer cell line.

PubMed

Meng, Huan; Liong, Monty; Xia, Tian; Li, Zongxi; Ji, Zhaoxia; Zink, Jeffrey I; Nel, Andre E

2010-08-24

Overexpression of drug efflux transporters such as P-glycoprotein (Pgp) protein is one of the major mechanisms for multiple drug resistance (MDR) in cancer cells. A new approach to overcome MDR is to use a co-delivery strategy that utilizes a siRNA to silence the expression of efflux transporter together with an appropriate anticancer drug for drug resistant cells. In this paper, we report that mesoporous silica nanoparticles (MSNP) can be functionalized to effectively deliver a chemotherapeutic agent doxorubicin (Dox) as well as Pgp siRNA to a drug-resistant cancer cell line (KB-V1 cells) to accomplish cell killing in an additive or synergistic fashion. The functionalization of the particle surface with a phosphonate group allows electrostatic binding of Dox to the porous interior, from where the drug could be released by acidification of the medium under abiotic and biotic conditions. In addition, phosphonate modification also allows exterior coating with the cationic polymer, polyethylenimine, which endows the MSNP to contemporaneously deliver Pgp siRNA. The dual delivery of Dox and siRNA in KB-V1 cells was capable of increasing the intracellular as well as intranuclear drug concentration to levels exceeding that of free Dox or the drug being delivered by MSNP in the absence of siRNA codelivery. These results demonstrate that it is possible to use the MSNP platform to effectively deliver a siRNA that knocks down gene expression of a drug exporter that can be used to improve drug sensitivity to a chemotherapeutic agent.

Engineered Design of Mesoporous Silica Nanoparticles to Deliver Doxorubicin and Pgp siRNA to Overcome Drug Resistance in a Cancer Cell Line

PubMed Central

Meng, Huan; Liong, Monty; Xia, Tian; Li, Zongxi; Ji, Zhaoxia; Zink, Jeffrey I.; Nel, Andre E.

2014-01-01

Overexpression of drug efflux transporters such as P-glycoprotein (P-gp) protein is one of the major mechanisms for multiple drug resistance (MDR) in cancer cells. A new approach to overcome MDR is to use a co-delivery strategy that utilizes a siRNA to silence the expression of efflux transporter together with an appropriate anti-cancer drug for drug resistant cells. In this paper, we report that mesoporous silica nanoparticles (MSNP) can be functionalized to effectively deliver a chemotherapeutic agent doxorubicin (Dox) as well as Pgp siRNA to a drug-resistant cancer cell line (KB-V1 cells) to accomplish cell killing in an additive or synergistic fashion. The functionalization of the particle surface with a phosphonate group allows electrostatic binding of Dox to the porous interior, from where the drug could be released by acidification of the medium under abiotic and biotic conditions. In addition, phosphonate modification also allows exterior coating with the cationic polymer, polyethylenimine (PEI), which endows the MSNP contemporaneously deliver Pgp siRNA. The dual delivery of Dox and siRNA in KB-V1 cells was capable of increasing the intracellular as well as intranuclear drug concentration to levels exceeding that of free Dox or the drug being delivered by MSNP in the absence of siRNA co-delivery. These results demonstrate that it is possible to use the MSNP platform to effectively deliver a siRNA that knocks down gene expression of a drug exporter that can be used to improve drug sensitivity to a chemotherapeutic agent. PMID:20731437

Structure and corrosion properties of PVD Cr-N coatings

NASA Astrophysics Data System (ADS)

Liu, C.; Bi, Q.; Ziegele, H.; Leyland, A.; Matthews, A.

2002-05-01

PVD Cr-N coatings produced by physical vapor deposition (PVD) are increasingly used for mechanical and tribological applications in various industrial sectors. These coatings are particularly attractive for their excellent corrosion resistance, which further enhances the lifetime and service quality of coated components. PVD Cr-N coated steels in an aqueous solution are usually corroded by galvanic attack via through-coating ``permeable'' defects (e.g., pores). Therefore, the corrosion performance of Cr-N coated steel is determined by a number of variables of the coating properties and corrosive environment. These variables include: (i) surface continuity and uniformity; (ii) through-coating porosity; (iii) film density and chemical stability; (iv) growth stresses; (v) interfacial and intermediate layers; (vi) coating thickness; (vii) coating composition; and (viii) substrate properties. In this article, PVD Cr-N coatings were prepared, by electron-beam PVD and sputter deposition, with different compositions, thicknesses, and surface roughnesses, by changing the N2 flow rate, applying multilayering techniques and changing the substrate finish prior to coating. The microstructure of such coatings is investigated by various analytical techniques such as glancing angle x-ray diffraction and scanning electron microscopy, which are also correlated with the corrosion performance of the coated steel. Both dc polarization and ac impedance spectroscopy were employed to investigate the corrosion resistance of Cr-N coated steel in a 0.5N NaCl solution. It has been found that the N2 flow rate during reactive deposition strongly determines the microstructure of Cr-N coatings (due to the changing nitrogen content in the film) and can thus affect the corrosion resistance of coated systems. The surface finish of the steel substrate also affects the uniformity and coverage of PVD coatings; grooves and inclusions on the original substrate can raise the susceptibility of coated systems to crevice corrosion. Increased coating thickness can also greatly reduce the incidence of through-coating porosity such that the improvement in corrosion performance of thicker Cr-N coatings is significant.

Trowelable ablative coating composition and method of use

NASA Technical Reports Server (NTRS)

Headrick, Stephen E. (Inventor); Hill, Roger L. (Inventor)

1989-01-01

A trowelable ablative coating composition is disclosed. The composition comprises an epoxy resin, an amide curing agent, glass microspheres and ground cork. A method for protecting a substrate is also disclosed. The method comprises applying the trowelable ablative coating discussed above to a substrate and curing the coating composition.

Trowelable ablative coating composition and method of use

NASA Technical Reports Server (NTRS)

Headrick, Stephen E. (Inventor); Hill, Roger L. (Inventor)

1988-01-01

A trowelable ablative coating composition is disclosed. The composition comprises an epoxy resin, an amide curing agent, glass microspheres and ground cork. A method for protecting a substrate is also disclosed. The method comprises applying the trowelable ablative coating discussed above to a substrate and curing the coating composition.

Preparation of polystyrene brush film by radical chain-transfer polymerization and micromechanical properties

NASA Astrophysics Data System (ADS)

Zhao, Jing; Chen, Miao; An, Yanqing; Liu, Jianxi; Yan, Fengyuan

2008-12-01

A radical chain-transfer polymerization technique has been applied to graft-polymerize brushes of polystyrene (PSt) on single-crystal silicon substrates. 3-Mercapto-propyltrimethoxysilane (MPTMS), as a chain-transfer agent for grafting, was immobilized on the silicon surface by a self-assembling process. The structure and morphology of the graft-functionalized silicon surfaces were characterized by the means of contact-angle measurement, ellipsometric thickness measurement, Fourier transformation infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The nanotribological and micromechanical properties of the as-prepared polymer brush films were investigated by frictional force microscopy (FFM), force-volume analysis and scratch test. The results indicate that the friction properties of the grafted polymer films can be improved significantly by the treatment of toluene, and the chemically bonded polystyrene film exhibits superior scratch resistance behavior compared with the spin-coated polystyrene film. The resultant polystyrene brush film is expected to develop as a potential lubrication coating for microelectromechanical systems (MEMS).

Study of electroless Ni-W-P alloy coating on martensitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikitasari, Arini, E-mail: arini-nikitasari@yahoo.com; Mabruri, Efendi, E-mail: efendi-lipi@yahoo.com

Electroless nickel phospor (Ni-P) is widely used in many industries due to their corrosion and wear resistance, coating uniformity, and ability to coat non-conductive surfaces. The unique properties of tungsten such as high hardness, higher melting point, lower coefficient of linear thermal expansion, and high tensile strength have created a lot of interest in developing ternary Ni-W-P alloys. This article presents the study of electroless Ni-W-P alloys coating using acid or alkaline bath on martensitic stainless steel. Nickel sulfate and sodium tungstate were used as nickel and tungsten sources, respectively, and sodium hypophosphite was used as a reducing agent. Acidmore » or alkaline bath refer to bath pH condition was adjusted by adding sulfuric acid. Martensitic stainless steel was immersed in Ni-W-P bath for 15, 30, and 60 minutes. The substrate of martensitic stainless steel was subjected to pre-treatment (polishing and cleaning) and activation prior to electroless plating. The plating characteristics were investigated for concentration ratio of nickel and hypophosphite (1:3), sodium tungstate concentration 0,1 M, immersion time (15 min, 30 min, 60 min), and bath condition (acid, alkaline). The electroless Ni-W-P plating was heat treated at 400°C for 1 hour. Deposits were characterized using scanning electron microscope (SEM) and corrosion measurement system (CMS).« less

Layer-by-Layer Assembled Architecture of Polyelectrolyte Multilayers and Graphene Sheets on Hollow Carbon Spheres/Sulfur Composite for High-Performance Lithium-Sulfur Batteries.

PubMed

Wu, Feng; Li, Jian; Su, Yuefeng; Wang, Jing; Yang, Wen; Li, Ning; Chen, Lai; Chen, Shi; Chen, Renjie; Bao, Liying

2016-09-14

In the present work, polyelectrolyte multilayers (PEMs) and graphene sheets are applied to sequentially coat on the surface of hollow carbon spheres/sulfur composite by a flexible layer-by-layer (LBL) self-assembly strategy. Owing to the strong electrostatic interactions between the opposite charged materials, the coating agents are very stable and the coating procedure is highly efficient. The LBL film shows prominent impact on the stability of the cathode by acting as not only a basic physical barrier, and more importantly, an ion-permselective film to block the polysulfides anions by Coulombic repulsion. Furthermore, the graphene sheets can help to stabilize the polyelectrolytes film and greatly reduce the inner resistance of the electrode by changing the transport of the electrons from a "point-to-point" mode to a more effective "plane-to-point'' mode. On the basis of the synergistic effect of the PEMs and graphene sheets, the fabricated composite electrode exhibits very stable cycling stability for over 200 cycles at 1 A g(-1), along with a high average Coulombic efficiency of 99%. With the advantages of rapid and controllable fabrication of the LBL coating film, the multifunctional architecture developed in this study should inspire the design of other lithium-sulfur cathodes with unique physical and chemical properties.

Reducing bacteria and macrophage density on nanophase hydroxyapatite coated onto titanium surfaces without releasing pharmaceutical agents

NASA Astrophysics Data System (ADS)

Bhardwaj, Garima; Yazici, Hilal; Webster, Thomas J.

2015-04-01

Reducing bacterial density on titanium implant surfaces has been a major concern because of the increasing number of nosocomial infections. Controlling the inflammatory response post implantation has also been an important issue for medical devices due to the detrimental effects of chronic inflammation on device performance. It has recently been demonstrated that manipulating medical device surface properties including chemistry, roughness and wettability can control both infection and inflammation. Here, we synthesized nanophase (that is, materials with one dimension in the nanoscale) hydroxyapatite coatings on titanium to reduce bacterial adhesion and inflammatory responses (as measured by macrophage functions) and compared such results to bare titanium and plasma sprayed hydroxyapatite titanium coated surfaces used clinically today. This approach is a pharmaceutical-free approach to inhibit infection and inflammation due to the detrimental side effects of any drug released in the body. Here, nanophase hydroxyapatite was synthesized in sizes ranging from 110-170 nm and was subsequently coated onto titanium samples using electrophoretic deposition. Results indicated that smaller nanoscale hydroxyapatite features on titanium surfaces alone decreased bacterial attachment in the presence of gram negative (P. aeruginosa), gram positive (S. aureus) and ampicillin resistant gram-negative (E. coli) bacteria as well as were able to control inflammatory responses; properties which should lead to their further investigation for improved medical applications.

ϕX174 Procapsid Assembly: Effects of an Inhibitory External Scaffolding Protein and Resistant Coat Proteins In Vitro.

PubMed

Cherwa, James E; Tyson, Joshua; Bedwell, Gregory J; Brooke, Dewey; Edwards, Ashton G; Dokland, Terje; Prevelige, Peter E; Fane, Bentley A

2017-01-01

During ϕX174 morphogenesis, 240 copies of the external scaffolding protein D organize 12 pentameric assembly intermediates into procapsids, a reaction reconstituted in vitro In previous studies, ϕX174 strains resistant to exogenously expressed dominant lethal D genes were experimentally evolved. Resistance was achieved by the stepwise acquisition of coat protein mutations. Once resistance was established, a stimulatory D protein mutation that greatly increased strain fitness arose. In this study, in vitro biophysical and biochemical methods were utilized to elucidate the mechanistic details and evolutionary trade-offs created by the resistance mutations. The kinetics of procapsid formation was analyzed in vitro using wild-type, inhibitory, and experimentally evolved coat and scaffolding proteins. Our data suggest that viral fitness is correlated with in vitro assembly kinetics and demonstrate that in vivo experimental evolution can be analyzed within an in vitro biophysical context. Experimental evolution is an extremely valuable tool. Comparisons between ancestral and evolved genotypes suggest hypotheses regarding adaptive mechanisms. However, it is not always possible to rigorously test these hypotheses in vivo We applied in vitro biophysical and biochemical methods to elucidate the mechanistic details that allowed an experimentally evolved virus to become resistant to an antiviral protein and then evolve a productive use for that protein. Moreover, our results indicate that the respective roles of scaffolding and coat proteins may have been redistributed during the evolution of a two-scaffolding-protein system. In one-scaffolding-protein virus assembly systems, coat proteins promiscuously interact to form heterogeneous aberrant structures in the absence of scaffolding proteins. Thus, the scaffolding protein controls fidelity. During ϕX174 assembly, the external scaffolding protein acts like a coat protein, self-associating into large aberrant spherical structures in the absence of coat protein, whereas the coat protein appears to control fidelity. Copyright © 2016 American Society for Microbiology.

Deactivating Chemical Agents Using Enzyme-Coated Nanofibers Formed by Electrospinning

DTIC Science & Technology

2016-01-01

7.3mM/mg). Key words Coaxial electrospinning, DFPase, Enzyme, chemical warfare , nanofiber, decontamination . Introduction Chemical warfare ...Krile, R.; Nishioka, M.; Taylor, M.; Riggs, K.; Stone, H. Decontamination of Toxic Industrial Chemicals and Chemical Warfare Agents On Building...298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 MATS COATINGS ELECTROSPINNING CHEMICAL WARFARE

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Sugama, Toshifumi

1992-01-01

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR).sub.n (wherein M is Ti, Zr, Ge or Al; R is CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7 ; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., <1000.degree. C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Sugama, Toshifumi

1993-01-01

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR).sub.n (wherein M is Ti, Zr, Ge or Al; R is CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7 ; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., <1000.degree. C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Toshifumi Sugama.

1993-04-06

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR)[sub n] (wherein M is Ti, Zr, Ge or Al; R is CH[sub 3], C[sub 2]H[sub 5] or C[sub 3]H[sub 7]; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., < 1,000 C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Improved water resistance of SrAl2O4: Eu2+, Dy3+ phosphor directly achieved in a water-containing medium

NASA Astrophysics Data System (ADS)

Qi, Tonggang; Xia, Haofu; Zhang, Zhanhui; Kong, Shijin; Peng, Weikang; Zhao, Qi; Huang, Zhiliang

2017-03-01

In this paper, a heterogeneous precipitation method utilizing urea hydrolysis was adopted to coat a SiO2 layer on the surface of SrAl2O4:Eu2+, Dy3+ long persistence phosphors. To avoid phosphor hydrolysis in a water-containing coating medium, the hydrolysis and polymerization reactions of tetraethyl orthosilicate (TEOS) were concerned and carried out. The crystal phases, surface morphologies, hydrolysis stability and water resistance on afterglow properties of coated phosphors were investigated. Scanning electron microscopy, energy dispersive spectrum analysis, transmission electron microscope and Fourier transform infrared spectrum results confirmed that a continuous, uniform and compact SiO2 coating layer was successfully obtained on the phosphors surface. A theoretical coating amount of 5% or higher was found to be good for hydrolysis stability. Photoluminescence results revealed the coated phosphors showed much better water resistance on afterglow properties than the uncoated phosphor. We also discussed and proposed the hydrolysis restriction mechanism of SrAl2O4:Eu2+, Dy3+ in the water-containing coating medium.

Electrochemical Impedance Spectroscopy and Corrosion Behavior of Co/CeO2 Nanocomposite Coatings in Simulating Body Fluid Solution

NASA Astrophysics Data System (ADS)

Benea, Lidia

2013-02-01

A series of Co/CeO2 (25 nm) nanocomposite coating materials by electrodeposition were successfully prepared containing different cerium oxide composition in the cobalt-plating bath. Stainless steel (304L) was used as support material for nanocomposite coatings. The nano-CeO2 is uniformly incorporated into cobalt matrix, and the effect on surface morphologies was identified by scanning electron microscopy with energy-dispersive X-ray analysis. Codeposition of nano-CeO2 particles with cobalt disturbs the regular surface morphology of the cobalt coatings. It should be noted that the as-prepared Co/CeO2 nanocomposite coatings were found to be much superior in corrosion resistance over those of pure cobalt coatings materials based on a series of electrochemical impedance spectroscopy measurements in simulating body fluid solution. With increase in the nano-CeO2 particles concentration in the cobalt electrolyte, it is observed that the corrosion resistance of Co/CeO2 increases. Co/CeO2 nanocomposite coatings have higher polarization resistance as compared with pure cobalt layers in simulating body fluid solution.

High Current Plasma Electrolytic Oxidation Coating Processes for Wear and Corrosion Prevention of Al 2024

NASA Astrophysics Data System (ADS)

Wang, Rui

Plasma electrolytic oxidation (PEO) treatments have been used in the aerospace and automotive industries because the coating formed on light metals or alloys has great hardness, high wear, corrosion, and oxidation resistance, and a low friction coefficient that improves lifetime length and provide a higher surface quality. However, the PEO treatments that are presently used for industrial applications require a long period of time to confirm the quality of the coating. For this reason, the present study seeks to increase the current density of PEO treatments to improve their efficiency and explore the performance of the obtained coatings. It was found that for high current density (0.18A/cm2) PEO treatments, smaller ratio, such as 50% and 70%, is beneficial to obtaining a better performance coating. When compared with the coating of a "normal" (current density: 0.09A/cm2) PEO treatment, it had better wear resistance; however, for corrosion resistance, it had a lower performance than the coatings obtained by the "normal" current density PEO treatment which was attributed to the negative influence of porosity increase.

A biodegradable AZ91 magnesium alloy coated with a thin nanostructured hydroxyapatite for improving the corrosion resistance.

PubMed

Mukhametkaliyev, T M; Surmeneva, M A; Vladescu, A; Cotrut, C M; Braic, M; Dinu, M; Vranceanu, M D; Pana, I; Mueller, M; Surmenev, R A

2017-06-01

The main aim of this study was to investigate the properties of an AZ91 alloy coated with nanostructured hydroxyapatite (HA) prepared by radio frequency (RF) magnetron sputtering. The bioactivity and biomineralization of the AZ91 magnesium alloy coated with HA were investigated in simulated body fluid (SBF) via an in vitro test. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analyses were performed. The samples were immersed in SBF to study the ability of the surface to promote the formation of an apatite layer as well as corrosion resistance and mass change of the HA-coated AZ91 alloy. Electrochemical tests were performed to estimate the corrosion behaviour of HA-coated and uncoated samples. The results revealed the capability of the HA coating to significantly improve the corrosion resistance of the uncoated AZ91 alloy. Copyright © 2017 Elsevier B.V. All rights reserved.

NASA TEERM Hexavalent Chrome Alternatives Projects

NASA Technical Reports Server (NTRS)

Rothgeb, Matt

2009-01-01

This slide presentation reviews the NASA/DOD projects to select an alternative to hexavalent chrome in the aerospace industry. The Phase I process of the project performed: (1) Evaluation and testing of non-chromated coating systems as replacements for hexavalent chrome coatings in aircraft and aerospace applications. (2) Testing of coating systems to DoD and NASA specifications for corrosion resistance and adhesion. (3) Bare corrosion resistance and atmospheric exposure will be focus areas of Phase II Testing. The description includes a chart that summarizes the 3000 hour salt fog test results. The second phase of the project includes (1) Evaluation and testing of coating systems that do not contain hexavalent chrome as replacements for aerospace applications. (2) Evaluation of coatings at Beach Test Site and Launch Complex 39B (3) Evaluation of non-chrome coatings for electronic housings (bare corrosion resistance and electrical impedance) is a part of this round of testing. This project was performed for the Technology Evaluation for Environmental Risk Mitigation (TEERM)

Preparation and performance evaluation of epoxy-based heat reflective coating for the pavement

NASA Astrophysics Data System (ADS)

Hu, B.; Liang, Y. H.; Guo, L. Y.; Jiang, T.

2017-04-01

According to the basic characteristics and composition of heat-reflective coating, combining with the functional requirements of road materials, the experiment selects the epoxy resin with good wear resistance and adhesive force as a film forming material, with TiO2, SiO2 and extinction powder as the main functional filler. The experiment gets a good formula with suitable viscosity, low glossiness and good cooling effect, optimizes by orthogonal experiment. The experiment evaluates the indoor and outdoor cooling effect of heat-reflective coating, and analyses the road performance of the coating. The results shows that the better heat-reflective coating formula included 12% of titanium dioxide, 4% of silica and 4% of extinction powder. When the dosage of coating is 0.8kg/m2, the indoor specimen of heat-reflective coating decrease the temperature of 12 ˜ 14°C, and the specimen under solar radiation can reduce the temperature of 7 ˜ 9°C. The pavement of heat-reflective coating has good wear resistance, but the road slip resistance partly declines. Therefore, it needs to add the anti-sliding particles to meet the safe driving requirements.

Enhanced corrosion resistance and hemocompatibility of biomedical NiTi alloy by atmospheric-pressure plasma polymerized fluorine-rich coating

NASA Astrophysics Data System (ADS)

Li, Penghui; Li, Limin; Wang, Wenhao; Jin, Weihong; Liu, Xiangmei; Yeung, Kelvin W. K.; Chu, Paul K.

2014-04-01

To improve the corrosion resistance and hemocompatibility of biomedical NiTi alloy, hydrophobic polymer coatings are deposited by plasma polymerization in the presence of a fluorine-containing precursor using an atmospheric-pressure plasma jet. This process takes place at a low temperature in air and can be used to deposit fluoropolymer films using organic compounds that cannot be achieved by conventional polymerization techniques. The composition and chemical states of the polymer coatings are characterized by fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the coated and bare NiTi samples is assessed and compared by polarization tests and electrochemical impedance spectroscopy (EIS) in physiological solutions including simulated body fluids (SBF) and Dulbecco's Modified Eagle's medium (DMEM). The corrosion resistance of the coated NiTi alloy is evidently improved. Protein adsorption and platelet adhesion tests reveal that the adsorption ratio of albumin to fibrinogen is increased and the number of adherent platelets on the coating is greatly reduced. The plasma polymerized coating renders NiTi better in vitro hemocompatibility and is promising as a protective and hemocompatible coating on cardiovascular implants.

Review of Thermal Spray Coating Applications in the Steel Industry: Part 2—Zinc Pot Hardware in the Continuous Galvanizing Line

NASA Astrophysics Data System (ADS)

Matthews, S.; James, B.

2010-12-01

This two-part article series reviews the application of thermal spray coating technology in the production of steel and steel sheet products. Part 2 of this article series is dedicated to coating solutions in the continuous galvanizing line. The corrosion mechanisms of Fe- and Co-based bulk materials are briefly reviewed as a basis for the development of thermal spray coating solutions. WC-Co thermal spray coatings are commonly applied to low Al-content galvanizing hardware due to their superior corrosion resistance compared to Fe and Co alloys. The effect of phase degradation, carbon content, and WC grain size are discussed. At high Al concentrations, the properties of WC-Co coatings degrade significantly, leading to the application of oxide-based coatings and corrosion-resistant boride containing coatings. The latest results of testing are summarized, highlighting the critical coating parameters.

Remanufacture of Zirconium-Based Conversion Coatings on the Surface of Magnesium Alloy

NASA Astrophysics Data System (ADS)

Liu, Zhe; Jin, Guo; Song, Jiahui; Cui, Xiufang; Cai, Zhaobing

2017-04-01

Brush plating provides an effective method for creating a coating on substrates of various shapes. A corroded zirconium-based conversion coating was removed from the surface of a magnesium alloy and then replaced with new coatings prepared via brush plating. The structure and composition of the remanufactured coating were determined via x-ray photoelectron spectroscopy, x-ray diffraction, and Fourier transform infrared spectroscopy. The results revealed that the coatings consist of oxide, fluoride, and tannin-related organics. The composition of the coatings varied with the voltage. Furthermore, as revealed via potentiodynamic polarization spectroscopy, these coatings yielded a significant increase in the corrosion resistance of the magnesium alloy. The friction coefficient remained constant for almost 300s during wear resistance measurements performed under a 1-N load and dry sliding conditions, indicating that the remanufactured coatings provide effective inhibition to corrosion.

A durability test rig and methodology for erosion-resistant blade coatings in turbomachinery

NASA Astrophysics Data System (ADS)

Leithead, Sean Gregory

A durability test rig for erosion-resistant gas turbine engine compressor blade coatings was designed, completed and commissioned. Bare and coated 17-4PH steel V103-profile blades were rotated at up to 11500 rpm and impacted with Garnet sand for 5 hours at an average concentration of 2.51 gm3of air , at a blade leading edge Mach number of 0.50. The rig was determined to be an acceptable first stage axial compressor representation. Two types of 16 microm-thick coatings were tested: Titanium Nitride (TiN) and Chromium-Aluminum-Titanium Nitride (CrAlTiN), both applied using an Arc Physical Vapour Deposition technique at the National Research Council in Ottawa, Canada. A Leithead-Allan-Zhao (LAZ) score was created to compare the durability performance of uncoated and coated blades based on mass-loss and blade dimension changes. The bare blades' LAZ score was set as a benchmark of 1.00. The TiN-coated and CrAlTiN-coated blades obtained LAZ scores of 0.69 and 0.41, respectively. A lower score meant a more erosion-resistant coating. Major modes of blade wear included: trailing edge, leading edge and the rear suction surface. Trailing edge thickness was reduced, the leading edge became blunt, and the rear suction surface was scrubbed by overtip and recirculation zone vortices. It was found that the erosion effects of vortex flow were significant. Erosion damage due to reflected particles was not present due to the low blade solidity of 0.7. The rig is best suited for studying the performance of erosion-resistant coatings after they are proven effective in ASTM standardized testing. Keywords: erosion, compressor, coatings, turbomachinery, erosion rate, blade, experimental, gas turbine engine

Ballistic impact resistance of selected organic ophthalmic lenses.

PubMed

Chou, B Ralph; Yuen, Gloria S-C; Dain, Stephen J

2011-11-01

The aim was to assess the impact resistance of coated and uncoated mid-index spectacle lens materials using the ballistic impact test. Nominally plano lenses of each material in three thicknesses were obtained. The lenses were flat edged to a 50 mm diameter. Each lens was impacted by a 6.35 mm steel ball. Impact velocities were selected using the Zippy Estimation by Sequential Testing protocol to determine the threshold fracture impact velocity. Threshold fracture impact velocity generally increased with thickness; however, there was a wide variation in performance among the various lens materials at each thickness. In all but two instances, the differences in impact velocity at each thickness of lens material were significant. Comparison of the data for CR39 and Hoya Phoenix with the results of earlier studies showed that the lens mounting is a significant factor. The fracture velocities found in the present study were significantly lower than the fracture velocities found when the lens edge is restrained in the mounting. A scratch resistant coating reduced the impact resistance of CR39. The effect of the antireflection coating on the fracture velocity depended on the nature of the base scratch-resistant coating. Mid-index lens materials of the same thickness show widely varying levels of impact resistance under the ballistic test. Impact resistance increases non-linearly with centre thickness. The lens mounting might affect the results of the ballistic impact test. The presence of 'cushion coatings' might enhance impact resistance. © 2011 The Authors. Clinical and Experimental Optometry © 2011 Optometrists Association Australia.

Influence of sealing post-treatments on the corrosion resistance of PEO coated AZ91 magnesium alloy

NASA Astrophysics Data System (ADS)

Mingo, B.; Arrabal, R.; Mohedano, M.; Llamazares, Y.; Matykina, E.; Yerokhin, A.; Pardo, A.

2018-03-01

The effect of three different post-treatments carried out on Plasma Electrolytic Oxidation (PEO) coated magnesium alloys are evaluated in terms of characterisation and corrosion resistance. Special interest is given to the role of a common additive (NaF) to the coating properties. The post-treatments are based on immersion sealing processes in aqueous solutions of inorganic salts (cerium and stannate based salts) and alcoholic solution of an organic acid (octodecylphosphate acid, ODP). Sealing mechanisms for each post-treatment are proposed. Cerium and stannate sealings are based on filling of the pores with the products of dissolution/precipitation reactions, while the ODP acid sealing is based on the formation of a thin layer of ODP over the coating through specific interactions between the polar part of the organic acid and the coating surface. All coatings are evaluated by salt fog test and analysed by electrochemical impedance spectroscopy. All sealings show a slight increase in the corrosion resistance of the coatings formed in the NaF-free electrolyte, but their positive influence is boosted in case of the coatings obtained in the NaF-containing electrolyte. This is related to the chemical and morphological changes at the coating surface induced by the presence of NaF in the electrolyte.

Innovative micro-textured hydroxyapatite and poly(l-lactic)-acid polymer composite film as a flexible, corrosion resistant, biocompatible, and bioactive coating for Mg implants.

PubMed

Kim, Sae-Mi; Kang, Min-Ho; Kim, Hyoun-Ee; Lim, Ho-Kyung; Byun, Soo-Hwan; Lee, Jong-Ho; Lee, Sung-Mi

2017-12-01

The utility of a novel ceramic/polymer-composite coating with a micro-textured microstructure that would significantly enhance the functions of biodegradable Mg implants is demonstrated here. To accomplish this, bioactive hydroxyapatite (HA) micro-dots can be created by immersing a Mg implant with a micro-patterned photoresist surface in an aqueous solution containing calcium and phosphate ions. The HA micro-dots can then be surrounded by a flexible poly(l-lactic)-acid (PLLA) polymer using spin coating to form a HA/PLLA micro-textured coating layer. The HA/PLLA micro-textured coating layer showed an excellent corrosion resistance when it was immersed in a simulated body fluid (SBF) solution and good biocompatibility, which was assessed by in vitro cell tests. In addition, the HA/PLLA micro-textured coating layer had high deformation ability, where no apparent changes in the coating layer were observed even after a 5% elongation, which would be unobtainable using HA and PLLA coating layers; furthermore, this allowed the mechanically-strained Mg implant with the HA/PLLA micro-textured coating layer to preserve its excellent corrosion resistance and biocompatibility in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Slurry Erosion Performance of Ni-Al2O3 Based Thermal-Sprayed Coatings: Effect of Angle of Impingement

NASA Astrophysics Data System (ADS)

Grewal, H. S.; Agrawal, Anupam; Singh, H.; Shollock, B. A.

2014-02-01

In this paper, slurry erosion performance of high velocity flame-sprayed Ni-Al2O3 based coatings was evaluated. The coatings were deposited on a hydroturbine steel (CA6NM) by varying the content of Al2O3 in Ni. Using jet-type test rig, erosion behavior of coatings and bare steel was evaluated at different impingement angles. Detailed investigation of the surface morphology of the eroded specimens was undertaken using SEM/EDS to identify potential erosion mechanism. A parameter named "erosion mechanism identifier" (ξ) was used to predict the mode of erosion. It was observed that the coating prepared using 40 wt.% of Al2O3 showed a highest resistance to erosion. This coating enhanced the erosion resistance of the steel by 2 to 4 times. Spalling in the form of splats and chunks of material (formed by interlinking of cracks) along with fracture of Al2O3 splats were identified as primary mechanisms responsible for the loss of coating material. The erosion mechanism of coatings and bare steel predicted by ξ was in good agreement with that observed experimentally. Among different parameters,, a function of fracture toughness ( K IC) and hardness ( H) showed excellent correlation with erosion resistance of coatings at both the impingement angles.

Microstructure and wear resistance of laser cladded Ni-Cr-Co-Ti-V high-entropy alloy coating after laser remelting processing

NASA Astrophysics Data System (ADS)

Cai, Zhaobing; Cui, Xiufang; Liu, Zhe; Li, Yang; Dong, Meiling; Jin, Guo

2018-02-01

An attempt, combined with the technologies of laser cladding and laser remelting, has been made to develop a Ni-Cr-Co-Ti-V high entropy alloy coating. The phase composition, microstructure, micro-hardness and wear resistance (rolling friction) were studied in detail. The results show that after laser remelting, the phase composition remains unchanged, that is, as-cladded coating and as-remelted coatings are all composed of (Ni, Co)Ti2 intermetallic compound, Ti-rich phase and BCC solid solution phase. However, after laser remelting, the volume fraction of Ti-rich phase increases significantly. Moreover, the micro-hardness is increased, up to ∼900 HV at the laser remelting parameters: laser power of 1 kW, laser spot diameter of 3 mm, and laser speed of 10 mm/s. Compared to the as-cladded high-entropy alloy coating, the as-remelted high-entropy alloy coatings have high friction coefficient and low wear mass loss, indicating that the wear resistance of as-remelted coatings is improved and suggesting practical applications, like coatings on brake pads for wear protection. The worn surface morphologies show that the worn mechanism of as-cladded and as-remelted high-entropy alloy coatings are adhesive wear.

Low emittance chromated chemical conversion coatings for spacecraft thermal control in low earth orbit

NASA Astrophysics Data System (ADS)

LeVesque, R. J.; DeJesus, R. R.; Jones, C. A.; Babel, H. W.

1996-03-01

Low emittance coatings were required on the inner side of micro-meteoroid shielding and other structures to minimize heat transfer from the sun illuminated side to the underlying structure. A program was undertaken to evaluate conversion coatings for long term use in space. The conversion coatings evaluated were Alodine 1200 with three different bath chemistries, Iridite 14-2, and Alodine 600. Although the primary emphasis was on evaluating how processing conditions influenced the infrared emittance, corrosion resistance and electrical bonding characteristics were also evaluated. All of the conversion coatings were able to provide the target emittance value of less than 0.10, although baths with ferricyanide accelerators required shorter immersion times than typical of standard shop practices. The balance between emittance, corrosion resistance, and electrical bonding were defined. Space environmental stability tests were conducted on conversion coated 2219 and 7075 aluminum. The emittance and the electrical bonding characteristics were not affected by the space exposure even though the coating dehydrated and mud cracking is evident under a microscope. The dehydration resulted in a loss of corrosion resistance which is a consideration for hardware returned to Earth. It was concluded that conversion coatings are acceptable thermal control coatings for long life spacecraft although additional work is recommended for solar exposed surfaces.

Interpenetrating phase ceramic/polymer composite coatings: Fabrication and characterization

NASA Astrophysics Data System (ADS)

Craig, Bradley Dene

The goals of this thesis research were to fabricate interpenetrating phase composite (IPC) ceramic/polymer coatings and to investigate the effect of the interconnected microstructure on the physical and wear properties of the coatings. IPC coatings with an interpenetrating phase microstructure were successfully fabricated by first forming a porous ceramic with an interconnected microstructure using a chemical bonding route (mainly reacting alpha-alumina (0.3 mum) with orthophosphoric acid to form a phosphate bond). Porosity within these ceramic coatings was easily controlled between 20 and 50 vol. % by phosphoric acid addition, and was measured by a new porosity measurement technique (thermogravimetric volatilization of liquids, or TVL) which was developed. The resulting ceramic preforms were infiltrated with a UV and thermally curable cycloaliphatic epoxide resin and cured. This fabrication route resulted in composite coatings with thicknesses ranging from ˜1mum to 100 mum with complete filling of open pore space. The physical properties of the composite coatings, including microhardness, flexural modulus and wear resistance, were evaluated as a function of processing variables, including orthophosphoric acid content and ceramic phase firing temperature, which affected the microstructure and interparticulate bonding between particles in the coatings. For example, microhardness increased from ˜30 on the Vicker's scale to well over 200 as interparticulate bonding was increased in the ceramic phase. Additionally, Taber wear resistance in the best TPC coatings was found to approach that of fully-densified alumina under certain conditions. Several factors were found to influence the wear mechanism in the IPC coating materials. Forming strong connections between ceramic particles led to up to an order of magnitude increase in the wear resistance. Additionally, coating microhardness and ceramic/polymer interfacial strength were studied and found to be important in determining the wear mechanism and wear resistance of IPC composite coatings. A qualitative theory for wear mechanisms in these coatings was developed. Finally, a series of transparent coatings were developed via a similar processing route, using smaller (˜90 nm) boehmite particles instead of 0.3 mum alpha-alumina. Physical property control was found to mimic that found in opaque coatings, and showed increasing surface adsorption characteristics with increasing phosphoric acid content.

Stability and Normal Zone Propagation Speed in YBCO Coated Conductors with Increased Interfacial Resistance (PREPRINT)

DTIC Science & Technology

2010-03-01

Astronomy Los Angeles, CA --------------------------------------------------- Ohio State University Columbus, OH REPORT NUMBER AFRL-RZ-WP-TP-2010...the value of the resistance may lead to a better compromise between stability and quench protection requirements than what is found in currently...compromise between stability and quench protection requirements than what is found in currently manufactured coated conductors. Index Terms—Coated

Laser surface alloying of FeCoCrAlNi high-entropy alloy on 304 stainless steel to enhance corrosion and cavitation erosion resistance

NASA Astrophysics Data System (ADS)

Zhang, S.; Wu, C. L.; Zhang, C. H.; Guan, M.; Tan, J. Z.

2016-10-01

FeCoCrAlNi high-entropy alloy coating was synthesized with premixed high-purity Co, Cr, Al and Ni powders on 304 stainless steel by laser surface alloying, aiming at improving corrosion and cavitation erosion resistance. Phase constituents, microstructure and microhardness were investigated using XRD, SEM, and microhardness tester, respectively. The cavitation erosion and electrochemical corrosion behavior of FeCoCrAlNi coating in 3.5% NaCl solution were also evaluated using an ultrasonic vibrator and potentiodynamic polarization measurement. Experimental results showed that with appropriate laser processing parameters, FeCoCrAlNi coating with good metallurgical bonding to the substrate could be achieved. FeCoCrAlNi coating was composed of a single BCC solid solution. The formation of simple solid solutions in HEAs was the combined effect of mixing entropy (ΔSmix), mixing enthalpy (ΔHmix), atom-size difference (δ) and valence electron concentration (VEC), and the effect of ΔSmix was much larger than that of the other factors. The microhardness of the FeCoCrAlNi coating was ~3 times that of the 304 stainless steel. Both the corrosion and cavitation erosion resistance of the coating were improved. The cavitation erosion resistance for FeCoCrAlNi HEA coating was ~7.6 times that of 304 stainless steel. The corrosion resistance was also improved as reflected by a reduction in the current density of one order of magnitude as compared with 304 stainless steel.

Surface Design and Engineering Toward Wear-Resistant, Self-Lubricant Diamond Films and Coatings. Chapter 10

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1999-01-01

This chapter describes three studies on the surface design, surface engineering, and tribology of chemical-vapor-deposited (CVD) diamond films and coatings toward wear-resistant, self-lubricating diamond films and coatings. Friction mechanisms and solid lubrication mechanisms of CVD diamond are stated. Effects of an amorphous hydrogenated carbon on CVD diamond, an amorphous, nondiamond carbon surface layer formed on CVD diamond by carbon and nitrogen ion implantation, and a materials combination of cubic boron nitride and CVD diamond on the adhesion, friction, and wear behaviors of CVD diamond in ultrahigh vacuum are described. How surface modification and the selected materials couple improved the tribological functionality of coatings, giving low coefficient of friction and good wear resistance, is explained.

Use of Repeated Fluoropolymer Suspensions to Obtain Composite Electrochemical Coating Based on Zinc

NASA Astrophysics Data System (ADS)

Musikhina, T. A.; Zemtsova, E. A.; Fuks, C. L.

2017-11-01

This article deals with the issues of utilization of the waste products of fluoropolymers, namely, the suspensions of fluoroplasts that have lost their consumer properties. Such waste is recommended to be used as a filler of zinc coatings to provide increased corrosion resistance. Using the method of mathematical planning of the experiment, the authors establish the optimal compositions of galvanizing chloride-ammonium electrolytes to obtain the corrosion-resistant composite electrochemical coatings (CEC) of zinc-fluoropolymer. As a result, coatings with a finely crystalline structure were obtained differing in the distribution pattern on the surface of the samples and depending on the variation in the zinc concentration in the electrolytes. The samples of steel reinforcement with the zinc-fluoropolymer coating were tested on corrosion resistance. The increase of anticorrosive properties in CEC zinc-fluoropolymer and a slight decrease in microhardness were indicated.

All-organic superhydrophobic coatings with mechanochemical robustness and liquid impalement resistance

NASA Astrophysics Data System (ADS)

Peng, Chaoyi; Chen, Zhuyang; Tiwari, Manish K.

2018-03-01

Superhydrophobicity is a remarkable evolutionary adaption manifested by several natural surfaces. Artificial superhydrophobic coatings with good mechanical robustness, substrate adhesion and chemical robustness have been achieved separately. However, a simultaneous demonstration of these features along with resistance to liquid impalement via high-speed drop/jet impact is challenging. Here, we describe all-organic, flexible superhydrophobic nanocomposite coatings that demonstrate strong mechanical robustness under cyclic tape peels and Taber abrasion, sustain exposure to highly corrosive media, namely aqua regia and sodium hydroxide solutions, and can be applied to surfaces through scalable techniques such as spraying and brushing. In addition, the mechanical flexibility of our coatings enables impalement resistance to high-speed drops and turbulent jets at least up to 35 m s-1 and a Weber number of 43,000. With multifaceted robustness and scalability, these coatings should find potential usage in harsh chemical engineering as well as infrastructure, transport vehicles and communication equipment.

Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

DOEpatents

Chow, R.; Loomis, G.E.; Thomas, I.M.

1999-03-16

Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (ca. 1.10--1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm. 2 figs.

Tribology Study of High-Technological Composite Coatings Applied Using High Velocity Oxy-Fuel

NASA Astrophysics Data System (ADS)

Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Ivanov, Pl; Kalichin, Zh

2018-01-01

In the work are studied the differential parameters of wear and wear resistance of high-tech composite coatings of powder superalloys with nickel matrix, WC-12Co and mixed compositions. Coatings were created and applied to a substrate of steel with a different flame velocity - 700 m/s and 1000 m/s without preheating the substrate and with preheating the substrate to 650° C. The wear is carried out with a "thumb-disk" tribotester under dry surface friction with fixed black corundum abrasive particles. Comparative results were obtained for the microstructure and texture of the pre- and post- friction coating, the porosity, roughness, hardness, the dependence of mass wear, the speed and wear intensity and the wear resistance of the coatings on the number of friction cycles. Influence of the flame rate and substrate temperature on wear resistance and differential wear parameters has been determined.

Quantitative image analysis for evaluating the abrasion resistance of nanoporous silica films on glass

PubMed Central

Nielsen, Karsten H.; Karlsson, Stefan; Limbach, Rene; Wondraczek, Lothar

2015-01-01

The abrasion resistance of coated glass surfaces is an important parameter for judging lifetime performance, but practical testing procedures remain overly simplistic and do often not allow for direct conclusions on real-world degradation. Here, we combine quantitative two-dimensional image analysis and mechanical abrasion into a facile tool for probing the abrasion resistance of anti-reflective (AR) coatings. We determine variations in the average coated area, during and after controlled abrasion. Through comparison with other experimental techniques, we show that this method provides a practical, rapid and versatile tool for the evaluation of the abrasion resistance of sol-gel-derived thin films on glass. The method yields informative data, which correlates with measurements of diffuse reflectance and is further supported by qualitative investigations through scanning electron microscopy. In particular, the method directly addresses degradation of coating performance, i.e., the gradual areal loss of antireflective functionality. As an exemplary subject, we studied the abrasion resistance of state-of-the-art nanoporous SiO2 thin films which were derived from 5–6 wt% aqueous solutions of potassium silicates, or from colloidal suspensions of SiO2 nanoparticles. It is shown how abrasion resistance is governed by coating density and film adhesion, defining the trade-off between optimal AR performance and acceptable mechanical performance. PMID:26656260

Effect of heat treatment duration on tribological behavior of electroless Ni-(high)P coatings

NASA Astrophysics Data System (ADS)

Biswas, A.; Das, S. K.; Sahoo, P.

2016-09-01

Electroless nickel coating occurs through an autocatalytic chemical reaction and without the aid of electricity. From tribological perspective, it is recommended due to its high hardness, wear resistance, lubricity and corrosion resistance properties. In this paper electroless Ni-P coatings with high phosphorous weight percentages are developed on mild steel (AISI 1040) substrates. The coatings are subjected to heat treatment at 300°C and 500°C for time durations up to 4 hours. The effect of heat treatment duration on the hardness as well as tribological properties is discussed in detail. Hardness is measured in a micro hardness tester while the tribological tests are carried out on a pin-on-disc tribotester. Wear is reported in the form of wear rates of the sample subjected to the test. As expected, heat treatment of electroless Ni-P coating results in enhancement in its hardness which in turn increases its wear resistance. The present study also finds that duration of heat treatment has quite an effect on the properties of the coating. Increase in heat treatment time in general results in increase in the hardness of the coating. Coefficient of friction is also found to be lesser for the samples heat treated for longer durations (4 hour). However, in case of wear, similar trend is not observed. Instead samples heat treated for 2 to 3 hour display better wear resistance compared to the same heat treated for 4 hour duration. The microstructure of the coating is also carried out to ensure about its proper development. From scanning electron microscopy (SEM), the coating is found to possess the conventional nodular structure while energy dispersive X-ray analysis (EDX) shows that the phosphorous content in the coating to be greater than 9%. This means that the current coating belongs to the high phosphorous category. From X-ray diffraction analysis (XRD), it is found that coating is amorphous in as-deposited condition but transforms into a crystalline structure with heat treatment.

An experimental, low-cost, silicon slurry/aluminide high-temperature coating for superalloys

NASA Technical Reports Server (NTRS)

Young, S. G.; Deadmore, D. L.

1979-01-01

A duplex silicon-slurry/aluminide coating has been developed and cyclically tested in Mach 1 combustion gases for oxidation and thermal fatigue resistance at 1093 C and in Mach 0.3 gases for hot-corrosion resistance at 900 C. The base-metal superalloys were VIA and B-1900. The coated B-1900 specimens performed much better in oxidation than similar specimens coated with aluminides and almost as well as the more-expensive Pt-Al and MCrAlY (where M is Ni and/or Co) coatings deposited by the physical vapor deposition process. The coating also provided good hot-corrosion protection. Metallographic, X-ray, and electron microprobe studies were made to characterize the coating, determine failure mechanisms, and study some of the changes due to exposure.

Improvement in Microstructure Performance of the NiCrBSi Reinforced Coating on TA15 Titanium Alloy

NASA Astrophysics Data System (ADS)

Peng, Li

2012-10-01

This work is based on the dry sliding wear of NiCrBSi reinforced coating deposited on TA15 titanium alloy using the laser cladding technique, the parameters of which were such as to provide almost crack-free coatings with minimum dilution and very low porosity. SEM results indicated that a laser clad coating with metallurgical joint to the substrate was formed. Compared with TA15 substrate, an improvement of the micro-hardness and wear resistance was observed for this composite coating. Rare earth oxide Y2O3 was beneficial in producing of the amorphous phases in laser clad coating. With addition of Y2O3, more amorphous alloys were produced, which increased the micro-hardness and wear resistance of the coating.

Cyclic Oxidation and Hot Corrosion of NiCrY-Coated Disk Superalloys

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Miller, Robert A.; Sudbrack, Chantal K.; Draper, Susan L.; Nesbitt, James A.; Rogers, Richard B.; Telesman, Ignacy; Ngo, Vanda; Healy, Jonathan

2016-01-01

Powder metallurgy disk superalloys have been designed for higher engine operating temperatures through improvement of their strength and creep resistance. Yet, increasing disk application temperatures to 704 degrees Centigrade and higher could enhance oxidation and activate hot corrosion in harmful environments. Protective coatings could be necessary to mitigate such attack. Cylindrical coated specimens of disk superalloys LSHR and ME3 were subjected to thermal cycling to produce cyclic oxidation in air at a maximum temperature of 760 degrees Centigrade. The effects of substrate roughness and coating thickness on coating integrity after cyclic oxidation were considered. Selected coated samples that had cyclic oxidation were then subjected to accelerated hot corrosion tests. This cyclic oxidation did not impair the coating's resistance to subsequent hot corrosion pitting attack.

Corrosive sliding wear behavior of laser clad Mo 2Ni 3Si/NiSi intermetallic coating

NASA Astrophysics Data System (ADS)

Lu, X. D.; Wang, H. M.

2005-05-01

Many ternary metal silicides such as W 2Ni 3Si, Ti 2Ni 3Si and Mo 2Ni 3Si with the topologically closed-packed (TCP) hP12 MgZn 2 type Laves phase crystal structure are expected to have outstanding wear and corrosion resistance due to their inherent high hardness and sluggish temperature dependence and strong atomic bonds. In this paper, Mo 2Ni 3Si/NiSi intermetallic coating was fabricated on substrate of an austenitic stainless steel AISI321 by laser cladding using Ni-Mo-Si elemental alloy powders. Microstructure of the coating was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Wear resistance of the coating is evaluated under corrosive sliding wear test condition. Influence of corrosion solutions on the wear resistance of the coating was studied and the wear mechanism was discussed based on observations of worn surface morphology. Results showed that the laser clad Mo 2Ni 3Si/NiSi composite coating have a fine microstructure of Mo 2Ni 3Si primary dendrites and the interdendritic Mo 2Ni 3Si/NiSi eutectics. The coating has excellent corrosive wear resistance compared with austenitic stainless steel AISI321 under acid, alkaline and saline corrosive environments.

Nanocomposite coatings on biomedical grade stainless steel for improved corrosion resistance and biocompatibility.

PubMed

Nagarajan, Srinivasan; Mohana, Marimuthu; Sudhagar, Pitchaimuthu; Raman, Vedarajan; Nishimura, Toshiyasu; Kim, Sanghyo; Kang, Yong Soo; Rajendran, Nallaiyan

2012-10-24

The 316 L stainless steel is one of the most commonly available commercial implant materials with a few limitations in its ease of biocompatibility and long-standing performance. Hence, porous TiO(2)/ZrO(2) nanocomposite coated over 316 L stainless steels was studied for their enhanced performance in terms of its biocompatibility and corrosion resistance, following a sol-gel process via dip-coating technique. The surface composition and porosity texture was studied to be uniform on the substrate. Biocompatibility studies on the TiO(2)/ZrO(2) nanocomposite coatings were investigated by placing the coated substrate in a simulated body fluid (SBF). The immersion procedure resulted in the complete coverage of the TiO(2)/ZrO(2) nanocomposite (coated on the surface of 316 L stainless steel) with the growth of a one-dimensional (1D) rod-like carbonate-containing apatite. The TiO(2)/ZrO(2) nanocomposite coated specimens showed a higher corrosion resistance in the SBF solution with an enhanced biocompatibility, surpassing the performance of the pure oxide coatings. The cell viability of TiO(2)/ZrO(2) nanocomposite coated implant surface was examined under human dermal fibroblasts culture, and it was observed that the composite coating enhances the proliferation through effective cellular attachment compared to pristine 316 L SS surface.

Electrochemical Behavior of Biomedical Titanium Alloys Coated with Diamond Carbon in Hanks' Solution

NASA Astrophysics Data System (ADS)

Gnanavel, S.; Ponnusamy, S.; Mohan, L.; Radhika, R.; Muthamizhchelvan, C.; Ramasubramanian, K.

2018-03-01

Biomedical implants in the knee and hip are frequent failures because of corrosion and stress on the joints. To solve this important problem, metal implants can be coated with diamond carbon, and this coating plays a critical role in providing an increased resistance to implants toward corrosion. In this study, we have employed diamond carbon coating over Ti-6Al-4V and Ti-13Nb-13Zr alloys using hot filament chemical vapor deposition method which is well-established coating process that significantly improves the resistance toward corrosion, wears and hardness. The diamond carbon-coated Ti-13Nb-13Zr alloy showed an increased microhardness in the range of 850 HV. Electrochemical impedance spectroscopy and polarization studies in SBF solution (simulated body fluid solution) were carried out to understand the in vitro behavior of uncoated as well as coated titanium alloys. The experimental results showed that the corrosion resistance of Ti-13Nb-13Zr alloy is relatively higher when compared with diamond carbon-coated Ti-6Al-4V alloys due to the presence of β phase in the Ti-13Nb-13Zr alloy. Electrochemical impedance results showed that the diamond carbon-coated alloys behave as an ideal capacitor in the body fluid solution. Moreover, the stability in mechanical properties during the corrosion process was maintained for diamond carbon-coated titanium alloys.

Comparative thermal fatigue resistances of twenty-six nickel and cobalt base alloys

NASA Technical Reports Server (NTRS)

Bizon, P. T.; Spera, D. A.

1975-01-01

Thermal fatigue resistances were determined from fluidized bed tests. Cycles to cracking differed by almost three orders of magnitude for these materials with directional solidification and surface protection of definite benefit. The alloy-coating combination with the highest thermal fatigue resistance was directionally solidified NASA TAZ-8A with an RT-XP coating. It oxidation resistance was excellent, showing almost no weight change after 15 000 fluidized bed cycles.

Demonstration of Antimicrobial Corrosion-Resisting Interior Coating Systems for Military Facilities in Warm, Humid Locations

DTIC Science & Technology

2017-06-01

ER D C/ CE RL T R- 17 -1 9 DoD Corrosion Prevention and Control Program Demonstration of Antimicrobial Corrosion- Resisting Interior ...Demonstration of Antimicrobial Corrosion- Resisting Interior Coating Systems for Military Facilities in Warm, Humid Locations Final Report on...Under Project F10-AR04, “Application of New Corrosion-Resistant Mold Abatement Technologies for Interior Surfaces of Buildings at Fort Polk, LA” ERDC