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Sample records for air powder abrasive

  1. Air Abrasion

    MedlinePlus

    ... delivered directly to your desktop! more... What Is Air Abrasion? Article Chapters What Is Air Abrasion? What Happens? The Pros and Cons Will I Feel Anything? Is Air Abrasion for Everyone? print full article print this ...

  2. In vitro effect of air-abrasion operating parameters on dynamic cutting characteristics of alumina and bio-active glass powders.

    PubMed

    Milly, H; Austin, R S; Thompson, I; Banerjee, A

    2014-01-01

    Minimally invasive dentistry advocates the maintenance of all repairable tooth structures during operative caries management in combination with remineralization strategies. This study evaluated the effect of air-abrasion operating parameters on its cutting efficiency/pattern using bio-active glass (BAG) powder and alumina powder as a control in order to develop its use as a minimally invasive operative technique. The cutting efficiency/pattern assessment on an enamel analogue, Macor, was preceded by studying the powder flow rate (PFR) of two different commercial intraoral air-abrasion units with differing powder-air admix systems. The parameters tested included air pressure, powder flow rate, nozzle-substrate distance, nozzle angle, shrouding the air stream with a curtain of water, and the chemistry of abrasive powder. The abraded troughs were scanned and analyzed using confocal white light profilometry and MountainsMap surface analysis software. Data were analyzed statistically using one-way and repeated-measures analysis of variance tests (p=0.05). The air-abrasion unit using a vibration mechanism to admix the abrasive powder with the air stream exhibited a constant PFR regardless of the set air pressure. Significant differences in cutting efficiency were observed according to the tested parameters (p<0.05). Alumina powder removed significantly more material than did BAG powder. Using low air pressure and suitable consideration of the effect of air-abrasion parameters on cutting efficiency/patterns can improve the ultraconservative cutting characteristics of BAG air-abrasion, thereby allowing an introduction of this technology for the controlled cleaning/removal of enamel, where it is indicated clinically. PMID:23718212

  3. [The application of air abrasion in dentistry].

    PubMed

    Mandinić, Zoran; Vulićević, Zoran R; Beloica, Milos; Radović, Ivana; Mandić, Jelena; Carević, Momir; Tekić, Jasmina

    2014-01-01

    One of the main objectives of contemporary dentistry is to preserve healthy tooth structure by applying techniques of noninvasive treatment. Air abrasion is a minimally invasive nonmechanical technique of tooth preparation that uses kinetic energy to remove carious tooth structure. A powerful narrow stream of moving aluminum-oxide particles hit the tooth surface and they abrade it without heat, vibration or noise. Variables that affect speed of cutting include air pressure, particle size, powder flow, tip's size, angle and distance from the tooth. It has been proposed that air abrasion can be used to diagnose early occlusal-surface lesions and treat them with minimal tooth preparation using magnifier. Reported advantages of air abrasion include reduced noise, vibration and sensitivity. Air abrasion cavity preparations have more rounded internal contours than those prepared with straight burs. This may increase the longevity of placed restorations because it reduces the incidence of fractures and a consequence of decreased internal stresses. However, air abrasion cannot be used for all patients, i.e. in cases involving severe dust allergy, asthma, chronic obstructive lung disease, recent extraction or other oral surgery, open wounds, advanced periodontal disease, recent placement of orthodontic appliances and oral abrasions, or subgingival caries removal. Many of these conditions increase the risk of air embolism in the oral soft tissues. Dust control is a challenge, and it necessitates the use of rubber dam, high-volume evacuation, protective masks and safety eyewear for both the patient and the therapist. PMID:24684041

  4. Decontamination using a desiccant with air powder abrasion followed by biphasic calcium sulfate grafting: a new treatment for peri-implantitis.

    PubMed

    Lombardo, Giorgio; Corrocher, Giovanni; Rovera, Angela; Pighi, Jacopo; Marincola, Mauro; Lehrberg, Jeffrey; Nocini, Pier Francesco

    2015-01-01

    Peri-implantitis is characterized by inflammation and crestal bone loss in the tissues surrounding implants. Contamination by deleterious bacteria in the peri-implant microenvironment is believed to be a major factor in the etiology of peri-implantitis. Prior to any therapeutic regenerative treatment, adequate decontamination of the peri-implant microenvironment must occur. Herein we present a novel approach to the treatment of peri-implantitis that incorporates the use of a topical desiccant (HYBENX), along with air powder abrasives as a means of decontamination, followed by the application of biphasic calcium sulfate combined with inorganic bovine bone material to augment the intrabony defect. We highlight the case of a 62-year-old man presenting peri-implantitis at two neighboring implants in positions 12 and 13, who underwent access flap surgery, followed by our procedure. After an uneventful 2-year healing period, both implants showed an absence of bleeding on probing, near complete regeneration of the missing bone, probing pocket depth reduction, and clinical attachment gain. While we observed a slight mucosal recession, there was no reduction in keratinized tissue. Based on the results described within, we conclude that the use of HYBENX and air powder abrasives, followed by bone defect grafting, represents a viable option in the treatment of peri-implantitis. PMID:26000178

  5. Decontamination Using a Desiccant with Air Powder Abrasion Followed by Biphasic Calcium Sulfate Grafting: A New Treatment for Peri-Implantitis

    PubMed Central

    Lombardo, Giorgio; Corrocher, Giovanni; Rovera, Angela; Pighi, Jacopo; Marincola, Mauro; Lehrberg, Jeffrey; Nocini, Pier Francesco

    2015-01-01

    Peri-implantitis is characterized by inflammation and crestal bone loss in the tissues surrounding implants. Contamination by deleterious bacteria in the peri-implant microenvironment is believed to be a major factor in the etiology of peri-implantitis. Prior to any therapeutic regenerative treatment, adequate decontamination of the peri-implant microenvironment must occur. Herein we present a novel approach to the treatment of peri-implantitis that incorporates the use of a topical desiccant (HYBENX), along with air powder abrasives as a means of decontamination, followed by the application of biphasic calcium sulfate combined with inorganic bovine bone material to augment the intrabony defect. We highlight the case of a 62-year-old man presenting peri-implantitis at two neighboring implants in positions 12 and 13, who underwent access flap surgery, followed by our procedure. After an uneventful 2-year healing period, both implants showed an absence of bleeding on probing, near complete regeneration of the missing bone, probing pocket depth reduction, and clinical attachment gain. While we observed a slight mucosal recession, there was no reduction in keratinized tissue. Based on the results described within, we conclude that the use of HYBENX and air powder abrasives, followed by bone defect grafting, represents a viable option in the treatment of peri-implantitis. PMID:26000178

  6. Air abrasion: an old technology reborn.

    PubMed

    Berry, E A; Eakle, W S; Summitt, J B

    1999-08-01

    Recently, air abrasion has experienced a rebirth in restorative dentistry. Originally developed in the late 1940s, the principle of air abrasion is the imparting of kinetic energy to tiny aluminum oxide particles that are projected by a stream of compressed air or gas and expelled from a small nozzle. The force generated by the relatively hard particles striking a relatively hard surface is sufficient to cut into that surface. In the last decade, more than a dozen models of air abrasion units have been introduced into the marketplace and more are on the way. Manufacturers have developed air abrasion instruments that offer a broad range of features, from small table-top units to self-contained systems with compressors, vacuums, and curing lights. The costs range dramatically--from $1,000 to $20,000 or more--depending on the complexity of the features and attachments. Manufacturers make a variety of claims to support the value of this technology to the practicing dentist. A term often used to describe one of the benefits of air abrasion is microdentistry. The claim is that smaller, less invasive tooth preparations may be accomplished using air abrasion than with a traditional bur and air turbine. This may be true in some instances, but it would certainly depend on the operator's experience and ability to visually discern fine detail. Other claims about air abrasion are that it can be used to cut into tooth structure without local anesthesia and that it should be used on all stained grooves or fissures to determine if incipient carious lesions are present. Despite the limited number of clinical studies, the popularity of air abrasion continues to grow. To gain additional insight about these claims and to see what might be on the horizon for this technology, I spoke with three highly respected educators who are recognized for their expertise in air abrasion. What they said should give the reader a better understanding of how air abrasion might augment restorative

  7. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study.

    PubMed

    Tan, Melissa H X; Hill, Robert G; Anderson, Paul

    2015-01-01

    Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38-80 μm) versus the conventional alumina abrasive (29 μm) in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p < 0.05) despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine. PMID:26697067

  8. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study

    PubMed Central

    Tan, Melissa H. X.; Hill, Robert G.; Anderson, Paul

    2015-01-01

    Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38–80 μm) versus the conventional alumina abrasive (29 μm) in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p < 0.05) despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine. PMID:26697067

  9. A new dimension to conservative dentistry: Air abrasion

    PubMed Central

    Hegde, Vivek S; Khatavkar, Roheet A

    2010-01-01

    Air abrasion dentistry has evolved over a period of time from a new concept of an alternative means of cavity preparation to an essential means of providing a truly conservative preparation for preservation of a maximal sound tooth structure. The development of bonded restorations in combination with air abrasion dentistry provides a truly minimal intervention dentistry. This article reviews the development of air abrasion, its clinical uses, and the essential accessories required for its use. PMID:20582212

  10. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    NASA Astrophysics Data System (ADS)

    Milly, Hussam; Andiappan, Manoharan; Thompson, Ian; Banerjee, Avijit

    2014-06-01

    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p < 0.001) and the effect of altering the unit's operating parameters was significant (p < 0.001). In conclusion, BAG powder is more efficient than alumina in the selective removal of resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  11. Soybean seedlings tolerate abrasion from air-propelled grit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New tools for controlling weeds would be useful for soybean production in organic systems. Air-propelled abrasive grit is one such tool that performs well for in-row weed control in corn, but crop safety in soybean is unknown. We examined responses to abrasion by corn-cob grit of soybean seedlings a...

  12. Air abrasion experiments in U-Pb dating of zircon

    USGS Publications Warehouse

    Goldich, S.S.; Fischer, L.B.

    1986-01-01

    Air abrasion of zircon grains can remove metamict material that has lost radiogenic Pb and zircon overgrowths that were added during younger events and thereby improve the precision of the age measurements and permit closer estimates of the original age. Age discordance that resulted from a single disturbance of the U-Pb isotopic decay systems, as had been demonstrated by T.E. Krogh, can be considerably reduced, and, under favorable conditions, the ages brought into concordancy. Two or more events complicate the U-Pb systematics, but a series of abrasion experiments can be helpful in deciphering the geologic history and in arriving at a useful interpretation of the probable times of origin and disturbances. In east-central Minnesota, U.S.A., Penokean tonalite gneiss is dated at 1869 ?? 5 Ma, and sheared granite gneiss is shown to have been a high-level granite intrusion at 1982 ?? 5 Ma in the McGrath Gneiss precursor. Tonalite gneiss and a mafic granodiorite in the Rainy Lake area, Ontario, Canada, are dated at 2736 ?? 16 and 2682 ?? 4 Ma, respectively. The tonalitic phase of the Morton Gneiss, southwestern Minnesota, is dated at 3662 ?? 42 Ma. ?? 1986.

  13. Potential Use of Abrasive Air-Propelled Agricultural Residues for Weed Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new postemergence weed control tactic is proposed for organic production systems that results in plant abrasion and death upon assault from abrasive grits propelled by compressed air. Grit derived from granulated walnut shells was delivered by a sand blaster at 517 kPa at distances of 30 to 60 cm ...

  14. Dry Flowing Abrasive Decontamination Technique for Pipe Systems with Swirling Air Flow

    SciTech Connect

    Kameo, Yutaka; Nakashima, Mikio; Hirabayashi, Takakuni

    2003-10-15

    A dry abrasive decontamination method was developed for removing radioactive corrosion products from surfaces of coolant pipe systems in decommissioning of a nuclear power plant. Erosion behavior of inside surfaces of stainless and carbon steel pipes by a swirling air flow containing alumina or cast-iron grit abrasive was studied. Erosion depths of the test pipes were approximately proportional to an abrasive concentration in air and an exponent of flow rate of airstream. The experimental results indicated that the present method could keep satisfactory erosion ability of abrasives even for a large-size pipe. The present method was successfully applied to {sup 60}Co-contaminated specimens sampled from a pipe of the water cleanup system of the Japan Power Demonstration Reactor.

  15. Potential of Air-Propelled Abrasives for Selective Weed Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Novel forms of selective weed control are needed by many types of growers, but especially organic growers who are restricted from using synthetic herbicides. Abrasive grit made from corn cobs was expelled from a sand blaster at 517 kPa pressure and aimed at seedlings of common lambsquarters and corn...

  16. Air-propelled abrasive grit for postemergence in-row weed control in field corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic growers need additional tools for weed control. A new technique involving abrasive grit propelled by compressed air was tested in field plots. Grit derived from corn cobs was directed at seedlings of summer annual weeds growing at the bases of corn plants when the corn was at differing early...

  17. Characterization of abrasion-induced nanoparticle release from paints into liquids and air

    NASA Astrophysics Data System (ADS)

    Golanski, L.; Gaborieau, A.; Guiot, A.; Uzu, G.; Chatenet, J.; Tardif, F.

    2011-07-01

    Two standard methods for the characterization of the abrasion nanoparticle release into air and liquid from coatings containing nanoparticles were developed. Details of the abrasion processes and the measurement methods are shown. Paints were formulated in an industrial facility. Standard abrasion conditions in wet environments were simulated. The size distribution of the particles abraded into liquid was analyzed by a laser granulometer: submicrometric and micrometric particles were observed, but no nanometric particles. The nanoparticles released in liquid were deposited on filters for SEM (Scanning Electron Microscopy) analysis. No free or agglomerated nanoparticles were observed by SEM: nanoparticles seem to remain embedded in the paint matrix. The same coatings were abraded in the air using another standard method. The ELPI (Electrical Low Pressure Impactor) was used to determine the number size distribution of the dust generated. Abrasion is found to produce submicrometric and micrometric particles in the air but no nanoparticles. Further characterizations by SEM confirmed that no free or agglomerated nanoparticles were emitted: nanoparticles seem to remain embedded in the paint matrix.

  18. Adhesive interfaces of enamel and dentin prepared by air-abrasion at different distances

    NASA Astrophysics Data System (ADS)

    Chinelatti, Michelle Alexandra; do Amaral, Thais Helena Andreolli; Borsatto, Maria Cristina; Palma-Dibb, Regina Guenka; Corona, Silmara Aparecida Milori

    2007-03-01

    The purpose of this study was to analyse, by scanning electron microscopy (SEM), the morphology of enamel and dentin/adhesive interfaces in cavities prepared by air-abrasion at different working distances. Thirty sound third human molars were selected and, on both their buccal and lingual surfaces, class V cavities were prepared by air-abrasion, at 2-, 4-, 6-, 8- and 10-mm working distances, or high-speed bur (control group). After preparation, all cavities were etched with 35% phosphoric acid gel and restored with Single Bond/Filtek Z-250. Buccal and lingual surfaces were separated and restorations sectioned in a buccolingual direction, providing two sections of each cavity, which were analysed by scanning electron microscopy. It was observed that the distances of 6 and 8 mm promoted more homogeneous dentin/adhesive interfaces, with tags formation, and more uniform for enamel, which were similar to the control group. It may be concluded that the air-abrasion working distance can influence the morphology of enamel and dentin/adhesive interfaces, and the intermediate distances provided better adhesive interfaces.

  19. Influence of sodium content on the properties of bioactive glasses for use in air abrasion.

    PubMed

    Farooq, Imran; Tylkowski, Maxi; Müller, Steffen; Janicki, Tomasz; Brauer, Delia S; Hill, Robert G

    2013-12-01

    Air abrasion is used in minimally invasive dentistry for preparing cavities, while removing no or little sound dentine or enamel, and the use of bioactive glass (rather than alumina) as an abrasive could aid in tooth remineralization. Melt-derived bioactive glasses (SiO2-P2O5-CaO-CaF2-Na2O) with low sodium content (0 to 10 mol% Na2O in exchange for CaO) for increased hardness, high phosphate content for high bioactivity and fluoride content for release of fluoride and formation of fluorapatite were produced, and particles between 38 and 80 µm in size were used for cutting soda-lime silicate glass microscope slides and human enamel. Vickers hardness increased with decreasing Na2O content, owing to a more compact silicate network in low sodium content glasses, resulting in shorter cutting times. Cutting times using bioactive glass were significantly longer than using the alumina control (29 µm) when tested on microscope slides; however, glasses showed more comparable results when cutting human enamel. The bioactive glasses formed apatite in Tris buffer within 6 h, which was significantly faster than Bioglass® 45S5 (24 h), suggesting that the hardness of the glasses makes them suitable for air abrasion application, while their high bioactivity and fluoride content make them of interest for tooth remineralization. PMID:24287337

  20. Effect of Bioactive Glass air Abrasion on Shear Bond Strength of Two Adhesive Resins to Decalcified Enamel

    PubMed Central

    Eshghi, Alireza; Khoroushi, Maryam; Rezvani, Alireza

    2014-01-01

    Objective: Bioactive glass air abrasion is a conservative technique to remove initial decalcified tissue and caries. This study examined the shear bond strength of composite resin to sound and decalcified enamel air-abraded by bioactive glass (BAG) or alumina using etch-and-rinse and self-etch adhesives. Materials and Methods: Forty-eight permanent molars were root-amputated and sectioned mesiodistally. The obtained 96 specimens were mounted in acrylic resin; the buccal and lingual surfaces remained exposed. A demineralizing solution was used to decalcify half the specimens. Both sound and decalcified specimens were divided into two groups of alumina and bioactive glass air abrasion. In each group, the specimens were subdivided into two subgroups of Clearfil SE Bond or OptiBond FL adhesives (n=12). Composite resin cylinders were bonded on enamel surfaces cured and underwent thermocycling. The specimens were tested for shear bond strength. Data were analyzed using SPSS 16.0 and three-way ANOVA (α=0.05). Similar to the experimental groups, the enamel surface of one specimen underwent SEM evaluation. Results: No significant differences were observed in composite resin bond strength subsequent to alumina or bioactive glass air abrasion preparation techniques (P=0.987). There were no statistically significant differences between the bond strength of etch-and-rinse and self-etch adhesive groups (P=1). Also, decalcified or intact enamel groups had no significant difference (P=0.918). However, SEM analysis showed much less enamel irregularities with BAG air abrasion compared to alumina air abrasion. Conclusion: Under the limitations of this study, preparation of both intact and decalcified enamel surfaces with bioactive glass air abrasion results in similar bond strength of composite resin in comparison with alumina air abrasion using etch-&-rinse or self-etch adhesives. PMID:25628694

  1. Peel strength of denture liner to PMMA and polyamide: laser versus air-abrasion

    PubMed Central

    Bagis, Bora; Özcan, Mutlu; Durkan, Rukiye; Turgut, Sedanur; Ates, Sabit Melih

    2013-01-01

    PURPOSE This study investigated the effect of laser parameters and air-abrasion on the peel strength of silicon-based soft denture liner to different denture resins. MATERIALS AND METHODS Specimens (N=180) were prepared out of three different denture base resins (Rodex, cross-linked denture base acrylic resin; Paladent, heat-cured acrylic resin; Deflex, Polyamide resin) (75 mm × 25 mm × 3 mm). A silicon-based soft denture liner (Molloplast B) was applied to the denture resins after the following conditioning methods: a) Air-abrasion (50 µm), b) Er,Cr:YSGG laser (Waterlase MD Turbo, Biolase Technology) at 2 W-20 Hz, c) Er,Cr:YSGG laser at 2 W-30 Hz, d) Er,Cr:YSGG laser at 3 W-20 Hz, e) Er,Cr:YSGG laser at 3 W-30 Hz. Non-conditioned group acted as the control group. Peel test was performed in a universal testing machine. Failure modes were evaluated visually. Data were analyzed using two-way ANOVA and Tukey's test (α=.05). RESULTS Denture liner tested showed increased peel strength after laser treatment with different parameters (3.9±0.4 - 5.58±0.6 MPa) compared to the control (3.64±0.5 - 4.58±0.5 MPa) and air-abraded groups (3.1±0.6 - 4.46±0.3 MPa), but the results were not statistically significant except for Paladent, with the pretreatment of Er,Cr:YSGG laser at 3 W-20 Hz. Polyamide resin after air-abrasion showed significantly lower peel strength than those of other groups (3.1±0.6 MPa). CONCLUSION Heat-cured acrylic resin, PMMA, may benefit from Er,Cr:YSGG laser treatment at 3 W-20 Hz irradiation. Air-abrasion of polyamide resins should be avoided not to impair their peel bond strengths to silicon-based soft denture liners. PMID:24049570

  2. Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion.

    PubMed

    Corona, Silmara Aparecida Milori; Borsatto, Maria Cristina; Rocha, Renata Andréa Salvitti de Sá; Palma-Dibb, Regina Guenka

    2005-01-01

    This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins. PMID:16113931

  3. Class III Restoration of Anterior Primary Teeth: In Vitro Retention Comparison of Conventional, Modified and Air-abrasion Treated Preparations

    PubMed Central

    Asl Aminabadi, Naser; Najafpour, Ebrahim; Erfanparast, Leila; Samiei, Mohammad; Haghifar, Monireh; Sighari Deljavan, Alireza; Jamali, Zahra; Pournaghi Azar, Fatemeh; Shokravi, Marzieh

    2014-01-01

    Background and aims. Anterior esthetic restoration is challenging in pediatric dentistry, due to limited durability and poor retention of the restoration.This study assessed the effect of air abrasion on tensile failure load of composite class III restorations using different preparation techniques. Materials and methods. 100 extracted human anterior primary teeth were divided, based on the preparation methods, into four groups each consisting of 25 subjects : conventional (A), labial surface bevel (B), conventional + air abrasion (C), and labial surface bevel + air abrasion (D). After restoring cavities, tensile failure load of samples was measured in Newton by Universal testing machine at a crosshead speed of 1 mm per minute. The data were analyzed by Kruskal-Wallis and Mann Whitney U tests using SPSS software. Results. There were statistically significant differences between groups A and C (P = 0.003), groups A and B (P & 0.001), groups A and D (P & 0.001), groups B and C (P = 0.028), groups B and D (P = 0.027), and also groups C and D (P& 0.001). Group D demonstrated the highest mean tensile failure load. Conclusion. Labial surface bevel treated by air abrasion showed significantly more retention of composite restoration. PMID:25093052

  4. Air permeability of powder: a potential tool for Dry Powder Inhaler formulation development.

    PubMed

    Le, V N P; Robins, E; Flament, M P

    2010-11-01

    Dry Powder Inhalers have drawn great attention from pharmaceutical scientists in recent years in particular those consisting of low-dose micronized drug particles associated with larger carrier particles and called interactive mixtures. However, there is little understanding of the relation between bulk powder properties such as powder structure and its aerodynamic dispersion performance. The aim of this work was to develop a simple method to measure the air permeability of interactive mixtures used in Dry Powder Inhalers by using Blaine's apparatus--a compendial permeameter and to relate it to the aerodynamic behaviour. The study was done with fluticasone propionate and terbutaline sulphate as drug models that were blended with several lactoses having different particle size distribution thus containing different percentages of fine particle lactose. The quality of the blends was examined by analysing the drug content uniformity. Aerodynamic evaluation of fine particle fraction was obtained using a Twin Stage Impinger. A linear correlation between a bulk property--air permeability of packed powder bed--and the fine particle fraction of drug was observed for the tested drugs. The air permeability reflects the quantity of the free particle fraction in the interparticulate spaces of powder bed that leads to fine particle fraction during fluidization in air flow. A theoretical approach was developed in order to link the air permeability of powder bed and drag force acting on powders during aerosolization process. The permeability technique developed in this study provides a potential tool for screening Dry Powder Inhaler formulations at the development stage. PMID:20854906

  5. Effects of air abrasion with alumina or glass beads on surface characteristics of CAD/CAM composite materials and the bond strength of resin cements

    PubMed Central

    Nobuaki, ARAO; Keiichi, YOSHIDA; Takashi, SAWASE

    2015-01-01

    ABSTRACT Objective The study aimed to evaluate effects of air abrasion with alumina or glass beads on bond strengths of resin cements to CAD/CAM composite materials. Material and Methods CAD/CAM composite block materials [Cerasmart (CS) and Block HC (BHC)] were pretreated as follows: (a) no treatment (None), (b) application of a ceramic primer (CP), (c) alumina-blasting at 0.2 MPa (AB), (d) AB followed by CP (AB+CP), and (e) glass-beads blasting at 0.4 MPa (GBB) followed by CP (GBB+CP). The composite specimens were bonded to resin composite disks using resin cements [G-CEM Cerasmart (GCCS) and ResiCem (RC)]. The bond strengths after 24 h (TC 0) and after thermal cycling (TC 10,000 at 4–60°C) were measured by shear tests. Three-way ANOVA and the Tukey compromise post hoc tests were used to analyze statistically significant differences between groups (α=0.05). Results For both CAD/CAM composite materials, the None group exhibited a significant decrease in bond strength after TC 10,000 (p<0.05). AB showed significantly higher bond strength after TC 10,000 than the None group, while CP did not (p<0.05). GBB exhibited smaller surface defects than did AB; however, their surface roughnesses were not significantly different (p>0.05). The AB+CP group showed a significantly higher bond strength after TC 10,000 than did the AB group for RC (p<0.05), but not for GCCS. The GBB+CP group showed the highest bond strength for both thermal cyclings (p<0.05). Conclusions Air abrasion with glass beads was more effective in increasing bond durability between the resin cements and CAD/CAM composite materials than was using an alumina powder and a CP. PMID:26814465

  6. Comparison of shear bond strength and surface structure between conventional acid etching and air-abrasion of human enamel.

    PubMed

    Olsen, M E; Bishara, S E; Damon, P; Jakobsen, J R

    1997-11-01

    Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p < or = 0.05. The results indicated that there was a significant difference in shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that

  7. Effect of Air Abrasion Preconditioning on Microleakage in Class V Restorations Under Cyclic Loading: An In-vitro Study

    PubMed Central

    Dharmani, Charan Kamal Kaur; Singh, Shamsher; Logani, Ajay; Shah, Naseem

    2014-01-01

    Background: Microleakage in class V Glass Ionomer Cement(GIC) or composite restorations at enamel or cementum margins has been cited as a reason for their failure. Air abrasion has been used to precondition tooth surface for increasing retention of such restorations. This study is done to evaluate the effect of preconditioning with air abrasion on microleakage in class V GIC and composite restorations. Materials and Methods: Class V cavities were prepared in 40 freshly extracted teeth. They were categorised into following four groups (n=10) depending on cavity preconditioning and restoration. Group I: 10% polyacrylic acid and GI (Ketac molar TM 3M ESPE); Group II: AA and GI; Group III: 35% Phosphoric acid and micro filled composite (MC) (Heliomolar, Ivoclar Vivadent); Group IV: AA and MC. Each group was further divided into subgroups A (no loading) & B (cyclic loading). Microleakage at occlusal and gingival margins was evaluated using methylene blue dye penetration method. Statistical analysis was done using Kruskal-wallis test and Mann-Whitney U test. Results: Microleakage at cementum margins was higher than at enamel margins in all the groups. Preconditioning with AA resulted in increased micro leakage. Conclusion: AA as a preconditioning agent was ineffective in producing superior tooth-restoration bonding. PMID:24995240

  8. Surface roughness and bond strength between Y-TZP and self-adhesive resin cement after air particle abrasion protocols.

    PubMed

    Sousa, Rafael Santiago de; Campos, Fernanda; Sarmento, Hugo Ramalho; Alves, Maria Luiza Lima; Dal Piva, Amanda Maria de Oliveira; Gondim, Laísa Daniel; Souza, Rodrigo Othávio Assunção

    2016-01-01

    The aim of this study was to evaluate the influence of different air particle abrasion (APA) protocols-with variations in particle types, duration of application, and the distance between the device tip and the ceramic-on the surface roughness (SR) of zirconia-based ceramic (yttria-stabilized tetragonal zirconia polycrystal [Y-TZP]) and the shear bond strength (SBS) between Y-TZP and resin cement. In total, 135 sintered Y-TZP blocks were polished and divided into 9 groups according to 3 factors: particle (alumina vs alumina coated with silica), duration (5 vs 10 seconds), and distance (contact vs 10 mm away). All 3 factors significantly influenced the SR values between the experimental groups and the control group. For SBS, only the particle type was a statistically significant factor. Results showed that air particle abrasion with silica-coated alumina resulted in higher SBS, even though the SR values associated with those groups were not the highest. PMID:27599282

  9. Magnetic analyses of powders from exhausted cabin air filters

    NASA Astrophysics Data System (ADS)

    Winkler, Aldo; Sagnotti, Leonardo

    2013-04-01

    The automotive cabin air filter is a pleated-paper filter placed in the outside-air intake for the car's passenger compartment. Dirty and saturated cabin air filters significantly reduce the airflow from the outside and introduce particulate matter (PM) and allergens (for example, pollen) into the cabin air stream. Magnetic measurements and analyses have been carried out on powders extracted from exhausted cabin air filters to characterize their magnetic properties and to compare them to those already reported for powders collected from disk brakes, gasoline exhaust pipes and Quercus ilex leaves. This study is also aimed at the identification and quantification of the contribution of the ultrafine fraction, superparamagnetic (SP) at room temperature, to the overall magnetic properties of these powders. This contribution was estimated by interpreting and comparing data from FORCs, isothermal remanent magnetization vs time decay curves, frequency and field dependence of the magnetic susceptibility and out-of-phase susceptibility. The magnetic properties and the distribution of the SP particles are generally homogenous and independent of the brand of the car, of the model of the filter and of its level of usage. The relatively high concentration of magnetic PM trapped in these filters poses relevant questions about the air quality inside a car.

  10. UPb ages of zircon rims: A new analytical method using the air-abrasion technique

    USGS Publications Warehouse

    Aleinikoff, J.N.; Winegarden, D.L.; Walter, M.

    1990-01-01

    We present a new technique for directly dating, by conventional techniques, the rims of zircons. Several circumstances, such as a xenocrystic or inherited component in igneous zircon and metamorphic overgrowths on igneous cores, can result in grains with physically distinct age components. Pneumatic abrasion has been previously shown by Krogh to remove overgrowths and damaged areas of zircon, leaving more resistant and isotopically less disturbed parts available for analysis. A new abrader design, which is capable of very gently grinding only tips and interfacial edges of even needle-like grains, permits easy collection of abraded material for dating. Five examples demonstrate the utility of the "dust-collecting" technique, including two studies that compare conventional, ion microprobe and abrader data. Common Pb may be strongly concentrated in the outermost zones of many zircons and this Pb is not easily removed by leaching (even in weak HF). Thus, the benefit of removing only the outermost zones (and avoiding mixing of age components) is somewhat compromised by the much higher common Pb contents which result in less precise age determinations. A very brief abrasion to remove the high common Pb zones prior to collection of material for dating is selected. ?? 1990.

  11. Influence of Air Abrasion and Sonic Technique on Microtensile Bond Strength of One-Step Self-Etch Adhesive on Human Dentin

    PubMed Central

    Anja, Baraba; Walter, Dukić; Nicoletta, Chieffi; Marco, Ferrari; Pezelj Ribarić, Sonja; Ivana, Miletić

    2015-01-01

    The purpose of this in vitro study was to evaluate the microtensile bond strength of one-step self-etch adhesive to human dentin surface modified with air abrasion and sonic technique and to assess the morphological characteristics of the pretreated dentin surface. The occlusal enamel was removed to obtain a flat dentin surface for thirty-six human molar teeth. The teeth were randomly divided into three experimental groups (n = 12 per group), according to the pretreatment of the dentin: (1) control group, (2) air abrasion group, and (3) sonic preparation group. Microtensile bond strength test was performed on a universal testing machine. Two specimens from each experimental group were subjected to SEM examination. There was no statistically significant difference in bond strength between the three experimental groups (P > 0.05). Mean microtensile bond strength (MPa) values were 35.3 ± 12.8 for control group, 35.8 ± 13.5 for air abrasion group, and 37.7 ± 12.0 for sonic preparation group. The use of air abrasion and sonic preparation with one-step self-etch adhesive does not appear to enhance or impair microtensile bond strength in dentin. PMID:25879053

  12. In vitro comparative bond strength of contemporary self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion.

    PubMed

    Blatz, Markus B; Phark, Jin-Ho; Ozer, Fusun; Mante, Francis K; Saleh, Najeed; Bergler, Michael; Sadan, Avishai

    2010-04-01

    This study compared shear bond strengths of six self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. One hundred twenty zirconia samples were air-abraded (group SB; n = 60) or left untreated (group NO). Composite cylinders were bonded to the zirconia samples with either BisCem (BC), Maxcem (MC), G-Cem (GC), RelyX Unicem Clicker (RUC), RelyX Unicem Applicator (RUA), or Clearfil SA Cement (CSA). Shear bond strength was tested after thermocycling, and data were analyzed with analysis of variance and Holm-Sidak pairwise comparisons. Without abrasion, RUA (8.0 MPa), GC (7.9 MPa), and CSA (7.6 MPa) revealed significantly higher bond strengths than the other cements. Air-particle abrasion increased bond strengths for all test cements (p < 0.001). GC (22.4 MPa) and CSA (18.4 MPa) revealed the highest bond strengths in group SB. Bond strengths of self-adhesive resin cements to zirconia were increased by air-particle abrasion. Cements containing adhesive monomers (MDP/4-META) were superior to other compositions. PMID:19415350

  13. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  14. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  15. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  16. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  17. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  18. PERFORMANCE OF ACTIVATED SLUDGE-POWDERED ACTIVATED CARBON-WET AIR REGENERATION SYSTEMS

    EPA Science Inventory

    The investigation summarized in this report was undertaken to evaluate the performance of powdered activated carbon (PAC) technology used in conjuntion with wet air regeneration (WAR) at municipal wastewater treatment plants. xcessive ash concentrations accumulated in the mixed l...

  19. PERFORMANCE OF ACTIVATED SLUDGE-POWDERED ACTIVATED CARBON-WET AIR REGENERATION SYSTEMS

    EPA Science Inventory

    The investigation summarized in the report was undertaken to evaluate the performance of powdered activated carbon (PAC) technology used in conjunction with wet air regeneration (WAR) at municipal wastewater treatment plants. Excessive ash concentrations accumulated in the mixed ...

  20. Livestock Air Treatment Using PVA-Coated Powdered Activated Carbon Biofilter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ideal biofilter media provide surface for attachment of microorganisms responsible for removing air-born contaminants while facilitating passage of air. This study evaluated the efficacy of polyvinyl alcohol (PVA)-coated powdered activated carbon particles as a biofiltration medium. This material e...

  1. Effect of particle size, air flow and inhaler device on the aerosolisation of disodium cromoglycate powders.

    PubMed

    Chew, N Y; Bagster, D F; Chan, H K

    2000-09-25

    Recently, the dispersion of mannitol powders has demonstrated the importance of particle size, air flow and inhaler device (Chew and Chan, 1999). The aim of the present study is to extend our investigation to a different compound, disodium cromoglycate (DSCG) powders. Solid state characteristics of the powders were assessed by particle sizing, scanning electron microscopy, X-ray powder diffraction, moisture content, particle density determination and freeze fracture. The aerosol behaviour of the powders was studied by dispersion using Rotahaler(R) and Dinkihaler(R), connected to a four-stage liquid impinger operating at 30-120 l/min. Three amorphous powders with a mass median diameter (MMD) of 2.3, 3.7, 5.2 microm and a similar polydispersity were prepared. The particles were nearly spherical with a particle density of 1.6 g/cm(3) and moisture content of 6.6 wt.%. Using Rotahaler(R), the maximum fine particle fraction (FPF(max)) for all three powders was only 15 wt.%, attained at the highest flow of 120 l/min. Using Dinkihaler(R), the FPF(max) was two to four times higher, being 36 and 29 wt.% for the 2.3 and 3.7 microm powder, respectively, at 60 l/min; and 18 wt.% for the 5.2 microm powder at 120 l/min. Hence, the study shows that the FPF in the DSCG powder aerosols was determined by the interaction of the particle size, air flow and inhaler design. The attribution of the amorphous nature and the different physico-chemical properties of the powder may explain the incomplete and low dispersibility of DSCG. PMID:11058812

  2. Bifunctional air electrodes containing elemental iron powder charging additive

    DOEpatents

    Liu, Chia-tsun; Demczyk, Brian G.; Gongaware, Paul R.

    1982-01-01

    A bifunctional air electrode for use in electrochemical energy cells is made, comprising a hydrophilic layer and a hydrophobic layer, where the hydrophilic layer essentially comprises a hydrophilic composite which includes: (i) carbon; (ii) elemental iron particles having a particle size of between about 25 microns and about 700 microns diameter; (iii) an oxygen evolution material; (iv) a nonwetting agent; and (v) a catalyst, where at least one current collector is formed into said composite.

  3. Spectroscopic Studies On Powdered CeNi5 Oxidized In Air

    SciTech Connect

    Coldea, M.; Pacurariu, R.; Pascut, L. G.; Rednic, V.; Neumann, M.

    2007-04-23

    The synthesis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of Ni isolated single domain particles, obtained from powdered CeNi5 oxidized in air at different temperatures up to 800 deg. C, are reported.

  4. Livestock air treatment using PVA-coated powdered activated carbon biofilter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of polyvinyl alcohol (PVA) biofilters was studied using bench-scale biofilters and air from aerobically-treated swine manure. The PVA-coated powdered activated carbon particles showed excellent properties as a biofiltration medium: water holding capacity of 1.39 g H2O/g-dry PVA; wet por...

  5. EVALUATION OF FULL SCALE ACTIVATED SLUDGE SYSTEMS UTILIZING POWDERED ACTIVATED CARBON ADDITION WITH WET AIR REGENERATION

    EPA Science Inventory

    The addition of powdered activated carbon (PAC) to activated sludge systems is a proven method of wastewater treatment. Of eleven POTWs in the U.S. that were designed for PAC use, ten included wet air regeneration (WAR) for the destruction of secondary sludge solids and recovery ...

  6. Particles at Oil-Air Surfaces: Powdered Oil, Liquid Oil Marbles, and Oil Foam.

    PubMed

    Binks, Bernard P; Johnston, Shaun K; Sekine, Tomoko; Tyowua, Andrew T

    2015-07-01

    The type of material stabilized by four kinds of fluorinated particles (sericite and bentonite platelet clays and spherical zinc oxide) in air-oil mixtures has been investigated. It depends on the particle wettability and the degree of shear. Upon vigorous agitation, oil dispersions are formed in all the oils containing relatively large bentonite particles and in oils of relatively low surface tension (γla < 26 mN m(-1)) like dodecane, 20 cS silicone, and cyclomethicone containing the other fluorinated particles. Particle-stabilized oil foams were obtained in oils having γla > 26 mN m(-1) where the advancing air-oil-solid contact angle θ lies between ca. 90° and 120°. Gentle shaking, however, gives oil-in-air liquid marbles with all the oil-particle systems except for cases where θ is <60°. For oils of tension >24 mN m(-1) with omniphobic zinc oxide and sericite particles for which advancing θ ≥ 90°, dry oil powders consisting of oil drops in air which do not leak oil could be made upon gentle agitation up to a critical oil:particle ratio (COPR). Above the COPR, catastrophic phase inversion of the dry oil powders to air-in-oil foams was observed. When sheared on a substrate, the dry oil powders containing at least 60 wt % of oil release the encapsulated oil, making these materials attractive formulations in the cosmetic and food industries. PMID:26107421

  7. Abrasion of 6 dentifrices measured by vertical scanning interference microscopy

    PubMed Central

    PASCARETTI-GRIZON, Florence; MABILLEAU, Guillaume; CHAPPARD, Daniel

    2013-01-01

    Objectives The abrasion of dentifrices is well recognized to eliminate the dental plaque. The aims of this study were to characterize the abrasive powders of 6 dentifrices (3 toothpastes and 3 toothpowders) and to measure the abrasion on a test surface by Vertical Scanning Interference microscopy (VSI). Material and Methods Bright field and polarization microscopy were used to identify the abrasive particles on the crude dentifrices and after prolonged washes. Scanning electron microscopy and microanalysis characterized the shape and nature of the particles. Standardized and polished blocks of poly(methylmethacrylate) were brushed with a commercial electric toothbrush with the dentifrices. VSI quantified the mean roughness (Ra) and illustrated in 3D the abraded areas. Results Toothpastes induced a limited abrasion. Toothpowders induced a significantly higher roughness linked to the size of the abrasive particles. One powder (Gencix® produced a high abrasion when used with a standard testing weight. However, the powder is based on pumice particles covered by a plant homogenate that readily dissolves in water. When used in the same volume, or after dispersion in water, Ra was markedly reduced. Conclusion Light and electron microscopy characterize the abrasive particles and VSI is a new tool allowing the analysis of large surface of abraded materials. PMID:24212995

  8. Preparation of superconductor Y-Ba-Cu-O powder by single step calcining in air

    NASA Astrophysics Data System (ADS)

    Duran, P.; Tartaj, J.; Fernandez, J. F.; Moure, C.; Colino, J.

    A combined suspension-coprecipitation powder-preparation method is described. The simultaneous coprecipitation of yttrium and copper cations in an aqueous BaCo3 suspension produced a homogeneous slurry of submicronized amorphous hydroxide particles surrounding the small BaCO3 which led to the formation of single-phase orthorhombic YBa2Cu3O(x) powders. Sintering of superconducting powder compacts at 940 C in air produced dense YBa2Cu3O(x) ceramic bodies which presented superconducting transition temperatures in the range of 87 K to 92 K. The values of critical current density (Jc) measured on sintered bulk samples were never higher than 15 A/sq cm due to the high anisotropy in Jc.

  9. Effects of air-polishing powders on color stability of composite resins

    PubMed Central

    GÜLER, Ahmet Umut; DURAN, Ibrahim; YÜCEL, Ali Çagin; ÖZKAN, Pelin

    2011-01-01

    Objectives The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials. Material and methods Thirty cylindrical specimens (15×2 mm) were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex). The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C) and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder). A standard air-polishing unit (ProSmile Handly) was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90º. Specimens were stored in 100 mL of coffee (Nescafe Classic) for 24 h at 37ºC. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300). Color differences (∆E*) between the 2 color measurements (baseline and after 24 h storage) were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p≤0.05). Results According to the 2-way ANOVA results, composite resin restorative materials, air-polishing powders, and their interaction were statistically significant (p<0.05) For Aelite Aesthetic Enemal, Filtek Z250, Grandio, CeramX Mono, and Quixfil composite resin restorative materials, no significant difference was observed between Group-PS and Group-CP (p>.05) and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less

  10. Air toxics in coal: Distribution and abundance of selected trace elements in the Powder River Basin

    SciTech Connect

    Crowley, S.S.; Stanton, R.W.

    1994-12-31

    The 1990 Clean Air Act Amendments identified 12 potentially toxic elements, called ``air toxics,`` that may be released during the combustion of coal. The elements identified in the amendments are As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, and U (radionuclides). In this study, the distribution and concentration of these elements were examined, on a whole-coal basis, in samples from two cores of the Wyodak-Anderson coal bed (Paleocene, Tongue River Member of the Fort Union Formation), in the Powder River Basin of Wyoming. The distribution of these elements in the Wyodak-Anderson coal bed is also compared to the distribution of the same elements in a correlative coal bed, the Anderson-Dietz 1 coal bed in the Powder River Basin of Montana.

  11. Plasma test on industrial diamond powder in hydrogen and air for fracture strength study

    NASA Astrophysics Data System (ADS)

    Chary, Rohit Asuri Sudharshana

    Diamonds are the most precious material all over the world. Ever since their discovery, the desire for natural diamonds has been great; recently, the demand has steeply increased, leading to scarcity. For example, in 2010, diamonds worth $50 billion were marketed. This increased demand has led to discovering alternative sources to replace diamonds. The diamond, being the hardest material on earth, could be replaced with no other material except another diamond. Thus, the industrial or synthetic diamond was invented. Because of extreme hardness is one of diamond's properties, diamonds are used in cutting operations. The fracture strength of diamond is one of the crucial factors that determine its life time as a cutting tool. Glow discharge is one of the techniques used for plasma formation. The glow discharge process is conducted in a vacuum chamber by ionizing gas atoms. Ions penetrate into the atomic structure, ejecting a secondary electron. The objective of this study is to determine the change in fracture strength of industrial diamond powder before and after plasma treatment. This study focuses mainly on the change in crystal defects and crushing strength (CS) of industrial diamond powder after the penetration of hydrogen gas, air and hydrogen-air mixture ions into the sample powder. For this study, an industrial diamond powder sample of 100 carats weight, along with its average fracture strength value was received from Engis Corporation, Illinois. The sample was divided into parts, each weighing 10-12 carats. At the University of Nevada, Las Vegas (UNLV), a plasma test was conducted on six sample parts for a total of 16 hours on each part. The three gas types mentioned above were used during plasma tests, with the pressure in vacuum chamber between 200 mTorr and 2 Torr. The plasma test on four sample parts was in the presence of hydrogen-air mixture. The first sample had chamber pressures between 200 mTorr and 400 mTorr. The remaining three samples had chamber

  12. Air classifier technology (ACT) in dry powder inhalation Part 3. Design and development of an air classifier family for the Novolizer multi-dose dry powder inhaler.

    PubMed

    de Boer, A H; Hagedoorn, P; Gjaltema, D; Goede, J; Frijlink, H W

    2006-03-01

    In this study, the design of a multifarious classifier family for different applications is described. The main design and development steps are presented as well as some special techniques that have been applied to achieve preset objectives. It is shown by increasing the number of air supply channels to the classifier chamber (from 2 to 8), that the fine particle losses from adhesion onto the classifier walls can be reduced from 75% to less than 5% of the real dose for soft (spherical) agglomerates. By applying a bypass flow that is arranged as a co-axial sheath of clean air around the aerosol cloud from the classifier, the airflow resistance of the classifier can be controlled over a relatively wide range of values (0.023-0.041 kPa(0.5) min l(-1)). This, without affecting the fine particle dose or increasing the fine particle losses in the inhaler. Moreover, the sheath flow can be modelled to reduce the depositions in the induction port to the cascade impactor or in the patient's mouth, which are the result of back flows in these regions. The principle of powder induced pressure drop reduction across a classifier enables assessment of the amount of powder in the classifier at any moment during inhalation, from which classifier loading (from the dose system) and discharge rates can be derived. This principle has been applied to study the residence time of a dose in the classifier as function of the carrier size fraction and the flow rate. It has been found that this residence time can be controlled in order to obtain an optimal balance between the generated fine particle fraction and the inhalation manoeuvre of the patient. A residence time between 0.5 and 2 s at 60 l/min is considered favourable, as this yields a high fine particle dose (depending on the type of formulation used) and leaves sufficient inhaled volume for particle transport into the deep lung. PMID:16442248

  13. Local ventilation for powder handling--combination of local supply and exhaust air.

    PubMed

    Heinonen, K; Kulmala, I; Säämänen, A

    1996-04-01

    The performance of a modified local ventilation unit equipped with local supply and exhaust ventilation was evaluated during the manual handling of flour additive powder. The investigation tested five different configurations to study the effects of the exhaust opening location and local supply air on worker exposure. The measurements were done under controlled conditions in a test room. The breathing zone (BZ) dust concentration was measured by gravimetric sampling and real time monitoring. The different local ventilation configurations were also modeled numerically using computational fluid dynamics. Without local ventilation the average BZ dust concentration was 42 mg/m3. With local exhaust only the exposure was reduced below 1 mg/m3. The addition of local supply air further reduced the exposure to below 0.5 mg/m3. The lowest results were achieved by locating two exhaust openings on either side of the contaminant source combined with local supply air. With this configuration the average BZ exposure was only 0.08 mg/m3, a reduction of 99.8%. Numerical simulations also gave useful information about the airflow fields in stationary conditions. However, the worker's exposure was greatly affected by body movements, and this was not possible to simulate numerically. The results of this investigation can be useful when controlling dust exposure in manual powder handling operations. PMID:8901237

  14. [Effect of air humidity on traditional Chinese medicine extract of spray drying process and prediction of its powder stability].

    PubMed

    He, Yan; Xie, Yin; Zheng, Long-jin; Liu, Wei; Rao, Xiao-yong; Luo, Xiao-jian

    2015-02-01

    In order to solve the adhesion and the softening problems of traditional Chinese medicine extract during spray drying, a new method of adding dehumidified air into spray drying process was proposed, and the storage stability conditions of extract powder could be predicted. Kouyanqing extract was taken as model drug to investigate on the wet air (RH = 70%) and dry air conditions of spray drying. Under the dry air condition, the influence of the spray drying result with different air compression ratio and the spray-dried powder properties (extract powder recovery rate, adhesion percentage, water content, angle of repose, compression ratio, particle size and distribution) with 100, 110, 120, 130, 140 °C inlet temperature were studied. The hygroscopic investigation and Tg value with different moisture content of ideal powder were determined. The water activity-equilibrium moisture content (aw-EMC) and the equilibrium moisture content-Tg (EMC-Tg) relationships were fitted by GAB equation and Gordon-Taylor model respectively, and the state diagram of kouyanqing powder was obtained to guide the rational storage conditions. The study found that in the condition of dry air, the extract powder water content decreased with the increase of air compression ratio and the spray drying effect with air compression ratio of 100% was the best performance; in the condition of wet air, the extract powder with high water content and low yield, and the value were 4.26% and 16.73 °C, while, in the dry air condition the values were 2.43% and 24.86 °C with the same other instru- ment parameters. From the analysis of kouyanqing powder state diagram, in order to keep the stability, the critical water content of 3.42% and the critical water content of 0.188. As the water decreased Tg value of extract powder is the major problem of causing adhesion and softening during spray drying, it is meaningful to aid dehumidified air during the process. PMID:26084164

  15. Heat treatment's effects on hydroxyapatite powders in water vapor and air atmosphere

    NASA Astrophysics Data System (ADS)

    Karabulut, A.; Baştan, F. E.; Erdoǧan, G.; Üstel, F.

    2015-03-01

    Hydroxyapatite (HA; Ca10(PO4)6(OH)2) is the main chemical constituent of bone tissue (~70%) as well as HA which is a calcium phosphate based ceramic material forms inorganic tissue of bone and tooth as hard tissues is used in production of prosthesis for synthetic bone, fractured and broken bone restoration, coating of metallic biomaterials and dental applications because of its bio compatibility. It is known that Hydroxyapatite decomposes with high heat energy after heat treatment. Therefore hydroxyapatite powders that heated in water vapor will less decomposed phases and lower amorphous phase content than in air atmosphere. In this study high purity hydroxyapatite powders were heat treated with open atmosphere furnace and water vapor atmosphere with 900, 1000, 1200 °C. Morphology of same powder size used in this process by SEM analyzed. Chemical structures of synthesized coatings have been examined by XRD. The determination of particle size and morphological structure of has been characterized by Particle Sizer, and SEM analysis, respectively. Weight change of sample was recorded by thermogravimetric analysis (TGA) during heating and cooling.

  16. Erythritol-Enriched Air-Polishing Powder for the Surgical Treatment of Peri-Implantitis.

    PubMed

    Taschieri, Silvio; Weinstein, Roberto; Del Fabbro, Massimo; Corbella, Stefano

    2015-01-01

    Peri-implantitis represents a major complication that can compromise the success and survival of implant-supported rehabilitations. Both surgical and nonsurgical treatment protocols were proposed to improve clinical parameters and to treat implants affected by peri-implantitis. A systematic review of the literature was performed on electronic databases. The use of air-polishing powder in surgical treatment of peri-implantitis was investigated. A total of five articles, of different study designs, were included in the review. A meta-analysis could not be performed. The data from included studies reported a substantial benefit of the use of air-polishing powders for the decontamination of implant surface in surgical protocols. A case report of guided bone regeneration in sites with implants affected by peri-implantitis was presented. Surgical treatment of peri-implantitis, though demanding and not supported by a wide scientific literature, could be considered a viable treatment option if an adequate decontamination of infected surfaces could be obtained. PMID:26065025

  17. Erythritol-Enriched Air-Polishing Powder for the Surgical Treatment of Peri-Implantitis

    PubMed Central

    Taschieri, Silvio; Weinstein, Roberto

    2015-01-01

    Peri-implantitis represents a major complication that can compromise the success and survival of implant-supported rehabilitations. Both surgical and nonsurgical treatment protocols were proposed to improve clinical parameters and to treat implants affected by peri-implantitis. A systematic review of the literature was performed on electronic databases. The use of air-polishing powder in surgical treatment of peri-implantitis was investigated. A total of five articles, of different study designs, were included in the review. A meta-analysis could not be performed. The data from included studies reported a substantial benefit of the use of air-polishing powders for the decontamination of implant surface in surgical protocols. A case report of guided bone regeneration in sites with implants affected by peri-implantitis was presented. Surgical treatment of peri-implantitis, though demanding and not supported by a wide scientific literature, could be considered a viable treatment option if an adequate decontamination of infected surfaces could be obtained. PMID:26065025

  18. Sterilization of soybean powder with plasma treatment in atmospheric humid air

    NASA Astrophysics Data System (ADS)

    Iwami, R.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.; Nakayama, A.; Nakagawa, K.

    2013-10-01

    Sterilization of foods has been performed by conventional methods such as heat, steam and chemical solutions. However, these sterilization techniques could cause damages to the food material. It is considered that plasma sterilization at atmospheric pressure is one of the promising alternative methods because of the low temperature process. In our previous study, the inactivation of Bacillus atrophaeusspores by a dielectric barrier discharge (DBD) plasma produced in atmospheric humid air was investigated in order to develop low-temperature, low-cost and high-speed plasma sterilization technique. The results showed that the inactivation of Bacillus atrophaeusspores was found to be dependent strongly on the humidity. In the present study, the plasma treatment technique in humid air is applied to sterilization of soybean powder. Effects of plasma sterilization were successfully confirmed by a colony counting method. It was found that the sterilization efficiency was increased by using the humid air as the discharge gas. In the conference, an improvement of the plasma treatment system to enhance the sterilization efficiency will be shown.

  19. Abrasive Wear Study of NiCrFeSiB Flame Sprayed Coating

    NASA Astrophysics Data System (ADS)

    Sharma, Satpal

    2013-10-01

    In the present study, abrasive wear behavior of NiCrFeSiB alloy coating on carbon steel was investigated. The NiCrFeSiB coating powder was deposited by flame spraying process. The microstructure, porosity and hardness of the coatings were evaluated. Elemental mapping was carried out in order to study the distribution of various elements in the coating. The abrasive wear behavior of these coatings was investigated under three normal loads (5, 10 and 15 N) and two abrasive grit sizes (120 and 320 grit). The abrasive wear rate was found to increase with the increase of load and abrasive size. The abrasive wear resistance of coating was found to be 2-3 times as compared to the substrate. Analysis of the scanning electron microscope images revealed cutting and plowing as the material removal mechanisms in these coatings under abrasive wear conditions used in this investigation.

  20. Influence of turbulent flow on the explosion parameters of micro- and nano-aluminum powder-air mixtures.

    PubMed

    Liu, Xueling; Zhang, Qi

    2015-12-15

    The environmental turbulence intensity has a significant influence on the explosion parameters of both micro- and nano-Al at the time of ignition. However, explosion research on turbulence intensity with respect to micro- and nano-Al powders is still insufficient. In this work, micro- and nano-aluminum powders were investigated via scanning electron microscopy (SEM), and their particle size distributions were measured using a laser diffraction analyzer under dispersing air pressures of 0.4, 0.6, and 0.8 MPa in a 20 L cylindrical, strong plexiglass vessel. The particle size distributions in three different mass ratio mixtures of micro- and nano-Al powders (micro-Al:nano-Al[massratio]=95:5, 90:10, and 85:15) were also measured. The results show that the agglomerate size of nano-Al powder is an order of magnitude larger than the nanoparticles' actual size. Furthermore, the turbulence intensity ranges (Urms) of the Al powder-air mixtures were measured using particle image velocimetry (PIV) under dispersing air pressures of 0.4, 0.6, and 0.8 MPa. The effect of turbulence intensity on the explosion characteristics of the micro- and nano-Al powders was investigated using a 20 L cylindrical explosion vessel. The results of micro-Al and nano-Al powder-air mixtures with a stoichiometric concentration of 337.00 g·m(-3) were discussed for the maximum explosion pressure, the maximum rate of pressure increase and the maximum effective burning velocity under the different turbulence intensity. PMID:26276701

  1. Valve for abrasive material

    DOEpatents

    Gardner, Harold S.

    1982-01-01

    A ball valve assembly for controlling the flow of abrasive particulates including an enlarged section at the bore inlet and an enlarged section at the bore outlet. A refractory ceramic annular deflector is positioned in each of the enlarged sections, substantially extending the useful life of the valve.

  2. Abrasion resistant heat pipe

    DOEpatents

    Ernst, Donald M.

    1984-10-23

    A specially constructed heat pipe 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.

  3. 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.

  4. Selective ablation of pit and fissure caries from occlusal surfaces using λ=355-nm laser pulses and air-abrasion demonstrated using PS-OCT and near-IR imaging

    NASA Astrophysics Data System (ADS)

    Ross, Steven T.; Fan, Kenneth; Fried, Daniel

    2006-02-01

    Several past studies have suggested that lasers with and without added chromophores can be used for the selective removal of dental caries from stained pit and fissures in preparation for composite sealant placement with minimal damage to sound, unstained tooth structure. Polarization sensitive optical coherence tomography (PS-OCT) is a new nondestructive imaging technology that can be used to acquire images of caries lesions in occlusal surfaces. PSOCT is ideally suited to measure the caries depth and severity before and after selective removal from occlusal surfaces. In this study, λ=355-nm laser pulses of 5-ns duration at irradiation intensities ranging from 0.5-1.3 J/cm2 were scanned across tooth surfaces to selectively remove decayed enamel with and without the addition of India ink. PS-OCT images were acquired before and after removal. The laser removal was also compared to air abrasion in order to compare selectivity of these two conservative caries removal technologies.

  5. Automated, low-temperature dielectric relaxation apparatus for measurement of air-sensitive, corrosive, hygroscopic, powdered samples

    NASA Astrophysics Data System (ADS)

    Bessonette, Paul W. R.; White, Mary Anne

    1999-07-01

    An automated apparatus for dielectric determinations on solid samples was designed to allow cryogenic measurements on air-sensitive, corrosive, hygroscopic, powdered samples, without determination of sample thickness, provided that it is uniform. A three-terminal design enabled measurements that were not affected by errors due to dimensional changes of the sample or the electrodes with changes in temperature. Meaningful dielectric data could be taken over the frequency range from 20 Hz to 1 MHz and the temperature range from 12 to 360 K. Tests with Teflon and with powdered NH4Cl gave results that were accurate within a few percent when compared with literature values.

  6. Plasma column and nano-powder generation from solid titanium by localized microwaves in air

    SciTech Connect

    Popescu, Simona; Jerby, Eli Meir, Yehuda; Ashkenazi, Dana; Barkay, Zahava; Mitchell, J. Brian A.; Le Garrec, Jean-Luc; Narayanan, Theyencheri

    2015-07-14

    This paper studies the effect of a plasma column ejected from solid titanium by localized microwaves in an ambient air atmosphere. Nanoparticles of titanium dioxide (titania) are found to be directly synthesized in this plasma column maintained by the microwave energy in the cavity. The process is initiated by a hotspot induced by localized microwaves, which melts the titanium substrate locally. The molten hotspot emits ionized titanium vapors continuously into the stable plasma column, which may last for more than a minute duration. The characterization of the dusty plasma obtained is performed in-situ by small-angle X-ray scattering (SAXS), optical spectroscopy, and microwave reflection analyses. The deposited titania nanoparticles are structurally and morphologically analyzed by ex-situ optical and scanning-electron microscope observations, and also by X-ray diffraction. Using the Boltzmann plot method combined with the SAXS results, the electron temperature and density in the dusty plasma are estimated as ∼0.4 eV and ∼10{sup 19 }m{sup −3}, respectively. The analysis of the plasma product reveals nanoparticles of titania in crystalline phases of anatase, brookite, and rutile. These are spatially arranged in various spherical, cubic, lamellar, and network forms. Several applications are considered for this process of titania nano-powder production.

  7. Abrasion protection in process piping

    SciTech Connect

    Accetta, J.

    1996-07-01

    Process piping often is subjected to failure from abrasion or a combination of abrasion and corrosion. Abrasion is a complex phenomenon, with many factors involved to varying degrees. Hard, mineral based alumina ceramic and basalt materials are used to provide protection against abrasion in many piping systems. Successful life extension examples are presented from many different industries. Lined piping components require special attention with regard to operating conditions as well as design and engineering considerations. Economic justification involves direct cost comparisons and avoided costs.

  8. Abrasion resistant composition

    DOEpatents

    Fischer, Keith D; Barnes, Christopher A; Henderson, Stephen L

    2014-05-13

    A surface covering composition of abrasion resistant character adapted for disposition in overlying bonded relation to a metal substrate. The surface covering composition includes metal carbide particles within a metal matrix at a packing factor of not less than about 0.6. Not less than about 40 percent by weight of the metal carbide particles are characterized by an effective diameter in the range of +14-32 mesh prior to introduction to the metal matrix. Not less than about 3 percent by weight of the metal carbide particles are characterized by an effective diameter of +60 mesh prior to introduction to the metal matrix.

  9. The Reaction Behavior of AlN Powder in Wet Air Between 1573 K and 1773 K

    NASA Astrophysics Data System (ADS)

    Wang, Enhui; Liu, Yanxiang; Chen, Junhong; Chou, Kuo-Chih; Hou, Xinmei

    2016-02-01

    The reaction behavior of aluminium nitride (AlN) powder at the temperature range of 1573 K to 1773 K in wet air was investigated using thermo-gravimetric analysis, x-ray diffraction and scanning electron microscopy. The results show that the reaction behavior of AlN powder in wet air depends on temperature and water content. Initially, weight increases quickly due to oxidation. Once the oxide product Al2O3 is formed, the volatile reaction caused by Al2O3 and H2O occurs simultaneously. Because of the appearance of cracks caused by the phase transformation of Al2O3, the reaction behavior is controlled both by oxidation and volatile reaction at a later stage. This phenomenon becomes more obvious with increasing water content. Based on the experimental result, the reaction kinetics is in reasonable agreement with the real physical picture model.

  10. Effect of binders on natural graphite powder-based gas diffusion electrode for Mg-air cell

    NASA Astrophysics Data System (ADS)

    Arinton, Ghenadi; Rianto, Anton; Faizal, Ferry; Hidayat, Darmawan; Hidayat, Sahrul; Panatarani, Camellia; Joni, I. Made

    2016-03-01

    This paper mainly discussed the electrical performance of gas diffusion electrode of Mg-Air Cell. The gas diffusion electrodes (GDE) use a natural graphite powder as catalyst material. The effect of additional binders to the GDE have been investigated to improve electrode performances. Several types of GDE have been developed using binder materials such as epoxy resin, natural clay, carboxymethyl cellulose (CMC) and urea-formaldehyde (UF). By using discharge performance measurement, the characteristics of the as-prepared GDEs are reported.

  11. Abrasive tip treatment for use on compressor blades

    NASA Technical Reports Server (NTRS)

    Pedersen, H. C.

    1984-01-01

    A co-spray process was used which simultaneously but separately introduces abrasive grits and metal matrix powder into the plasma stream and entraps the abrasive grits within a molten matrix to form an abrasive coating as the matrix material solidifies on test specimen surfaces. Spray trials were conducted to optimize spray parameter settings for the various matrix/grit combinations before actual spraying of the test specimens. Rub, erosion, and bond adhesion tests were conducted on the coated specimens in the as-sprayed condition as well as on coated specimens that were aged for 100 hours at a temperature of 866K (1100 F). Microscopic examinations were performed to determine the coating abrasive-particle content, the size and shape of the adhesive particles in the coating, and the extent of compositional or morphological changes resulting from the aging process. A nickel chromium/aluminum composite with No. 150 size (0.002 to 0.005 inch) silicon carbide grits was selected as the best matrix/abrasive combination of the candidates surveyed for coating compressor blade tips.

  12. Abrasion-resistant antireflective coating for polycarbonate

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J.

    1978-01-01

    Following plasma-polymerization technique, treatment in oxygen glow discharge further enhances abrasion resistance and transmission. Improvement in abrasion resistance was shown by measuring percentage of haze resulting from abrasion. Coating samples were analyzed for abrasion using standard fresh rubber eraser. Other tests included spectra measurements and elemental analysis with spectrometers and spectrophotometers.

  13. Mars Pathfinder Wheel Abrasion Experiment Ground Test

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Siebert, Mark W.

    1998-01-01

    The National Aeronautics and Space Administration (NASA) sent a mission to the martian surface, called Mars Pathfinder. The mission payload consisted of a lander and a rover. The primary purpose of the mission was demonstrating a novel entry, descent, and landing method that included a heat shield, a parachute, rockets, and a cocoon of giant air bags. Once on the surface, the spacecraft returned temperature measurements near the Martian surface, atmosphere pressure, wind speed measurements, and images from the lander and rover. The rover obtained 16 elemental measurements of rocks and soils, performed soil-mechanics, atmospheric sedimentation measurements, and soil abrasiveness measurements.

  14. Abrasives in snuff?

    PubMed

    Dahl, B L; Stølen, S O; Oilo, G

    1989-08-01

    The purpose of this study was to determine and calculate the inorganic contents of four brands of snuff. Visual inspection of wet snuff showed fairly large, yellow crystal-like particles. Scanning electron microscopy and X-ray dispersive (EDX) analyses were used to study both wet snuff and ashes of snuff, whereas light emission spectrography was used to determine elements in the ashes. The crystal-like particles did not dissolve in distilled water or in ethanol heated to 60 degrees C. EDX analyses showed that most elements remained in the particles after washing. The total weight percentage of inorganic material in snuff was calculated after burning dried snuff until constant weight was obtained. The ashes of snuff did not contain any crystal-like particles but consisted of a small-grained amorphous mass. The following elements were detected: Ag, Al, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, P, Pb, Si, Sr, Ti, Va, and Zr. Other elements such as rare earths were not searched for. The weight percentage of inorganic elements ranged between 12.35 +/- 0.69 and 20.95 +/- 0.81. Provided snuff is used in the same manner as chewing tobacco, and some people admit to doing so, there is a risk that its relatively high contents of inorganic material and heavily soluble salts may be conducive to excessive abrasion of teeth and restorations. PMID:2782061

  15. Quantitative characterization of agglomerate abrasion in a tumbling blender by using the Stokes number approach.

    PubMed

    Willemsz, Tofan A; Nguyen, Tien Thanh; Hooijmaijers, Ricardo; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

    2013-03-01

    Removal of microcrystalline cellulose agglomerates in a dry-mixing system (lactose, 100 M) predominantly occurs via abrasion. The agglomerate abrasion rate potential is estimated by the Stokes abrasion (StAbr) number of the system. The StAbr number equals the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. Basically, the StAbr number concept describes the blending condition of the dry-mixing system. The concept has been applied to investigate the relevance of process parameters on agglomerate abrasion in tumbling blenders. Here, process parameters such as blender rotational speed and relative fill volumes were investigated. In this study, the StAbr approach revealed a transition point between abrasion rate behaviors. Below this transition point, a blending condition exists where agglomerate abrasion is dominated by the kinetic energy density of the powder blend. Above this transition point, a blending condition exists where agglomerates show (undesirable) slow abrasion rates. In this situation, the blending condition is mainly determined by the high fill volume of the filler. PMID:23250711

  16. Study on measurement of the coal powder concentration in pneumatic pipes of a boiler with relationship between air velocity and pressure drop

    SciTech Connect

    Pan, W.; Shen, F.; Lin, W.; Chen, L.; Zhang, D.; Wang, Q.; Ke, J.; Quan, W.

    1999-07-01

    According to the theoretical relationship between air velocity and pressure drop in different solid-air mass flow in vertical pipes with the condition of upward air-solid flowing, the experimental research on measuring the coal powder concentration is directed against the pneumatic pipes of a boiler's combustion system in the energy industry. Through analyzing the experimental results, a mathematical model for measuring the coal powder concentration in pneumatic pipes is obtained. Then, the error analysis is done, and the method of on-line measurement and its function are provided.

  17. Conduit Coating Abrasion Testing

    NASA Technical Reports Server (NTRS)

    Sullivan, Mary K.

    2013-01-01

    During my summer internship at NASA I have been working alongside the team members of the RESTORE project. Engineers working on the RESTORE project are creating ·a device that can go into space and service satellites that no longer work due to gas shortage or other technical difficulties. In order to complete the task of refueling the satellite a hose needs to be used and covered with a material that can withstand effects of space. The conduit coating abrasion test will help the researchers figure out what type of thermal coating to use on the hose that will be refueling the satellites. The objective of the project is to determine whether or not the conduit coating will withstand the effects of space. For the RESTORE project I will help with various aspects of the testing that needed to be done in order to determine which type of conduit should be used for refueling the satellite. During my time on the project I will be assisting with wiring a relay board that connected to the test set up by soldering, configuring wires and testing for continuity. Prior to the testing I will work on creating the testing site and help write the procedure for the test. The testing will take place over a span of two weeks and lead to an informative conclusion. Working alongside various RESTORE team members I will assist with the project's documentation and records. All in all, throughout my internship at NASA I hope to learn a number of valuable skills and be a part of a hard working team of engineers.

  18. Abrasion Resistant Coating and Method of making the same

    SciTech Connect

    Sordelet, Daniel J.; Besser, Matthew F.

    1999-06-25

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al-Cu-Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  19. Abrasion resistant coating and method of making the same

    DOEpatents

    Sordelet, Daniel J.; Besser, Matthew F.

    2001-06-05

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al--Cu--Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  20. Mass flow rate measurement in abrasive jets using acoustic emission

    NASA Astrophysics Data System (ADS)

    Ivantsiv, V.; Spelt, J. K.; Papini, M.

    2009-09-01

    The repeatability of abrasive jet machining operations is presently limited by fluctuations in the mass flow rate due to powder compaction, stratification and humidity effects. It was found that the abrasive mass flow rate for a typical abrasive jet micromachining setup could be determined by using data from the acoustic emission of the abrasive jet impacting a flat plate. Two methods for extracting the mass flow rate from the acoustic emission were developed and compared. In the first method, the number of particle impacts per unit time was determined by a direct count of peaks in the acoustic emission signal. The second method utilizes the power spectrum density of the acoustic emission in a specific frequency range. Both measures were found to correlate strongly with the mass flow rate measured by weighing samples of blasted powder for controlled time periods. It was found that the peak count method permits measurement of the average frequency of the impacts and the mass flow rate, but can only be applied to flow rates in which the impact frequency is approximately one order of magnitude less than the frequency of the target plate ringing. The power spectrum density method of signal processing is applicable to relatively fine powders and to flow rates at which the average impact frequency is of the same order of magnitude as that of the ringing due to the impact. The acoustic emission technique can be used to monitor particle flow variations over a wide range of time periods and provides a straightforward and accurate means of process control.

  1. Air-coupled ultrasonic spectroscopy applied to the study of the properties of paper produced from mineral powder (mineral paper).

    NASA Astrophysics Data System (ADS)

    Soto, D. A.; Salas, R. A.; Alvarez-Arenas, T. E. Gómez

    2012-05-01

    A recent technology has been introduced into the paper industry that makes possible to produce paper materials by replacing the cellulose fibres by a mineral powder, achieving a more environmentally friendly product compared with conventional paper. The purpose of this work is to determine the possibilities of an air-coupled ultrasonic technique to study this kind of new materials in order to develop an ultrasonic system useful for quality control for this industry. In particular, air-coupled ultrasonic spectroscopy is specially well suited to this kind of materials because of the fact that no coupling liquid and no direct contact with the sample is employed. A through transmission technique is employed and Fourier analysis is performed to obtain both magnitude and phase spectra of the transmission coefficient. Properties in the thickness direction as well as in the paper plane are investigated. Different paper grades (from 120 to 400 g/m2) provided by Terraskin have been studied. Very high attenuation coeficientes and very low propagation velocities (and hence elastic constant) are obtained, this can be explained by considering the large porosity of this material (about 50%) and the microstrucutre: solid grains in contact with a variable amount of polymeric resin partially filling the pore space.

  2. Abrasion of restorative materials by toothaste.

    PubMed

    Heath, J R; Wilson, H J

    1976-04-01

    The procedure developed in this investigation is suitable for determining the abrasion resistance of restorative materials to toothbrush/dentifrice abrasion. Ideally, a restoration should have an abrasion resistance similar to that of enamel. Of the materials tested, gold was the only one that wore slightly less than enamel, whilst amalgam wore almost twice as quickly. The silicate material and composites (excluding TD.71) wear away 2-4 times faster than enamel. TD.71 and especially the unfilled resin exhibited very high rates of abrasion. After prolonged toothbrush/dentifrice abrasion, the surfaces of gold and amalgam were considerably smoother than those of the silicate and composite materials. PMID:1066445

  3. Abrasive wear behavior of P/M titanium metal-matrix composites

    SciTech Connect

    Alman, D.E.; Hawk, J.A.; Simmons, J.W.

    1997-01-01

    The abrasive wear behavior of titanium metal-matrix composites produced by powder metallurgical techniques was studied. Ti powder was mixed with 0, 20, or 40 volume percent (v%) TiB2, TiC, TiN, SiC, an B4C powder to produce a composite powder blend. The blends were consolidated by hot-pressing at 1200° C and 20 MPa for 2 hours. Also a series of Ti-TiB2 composites was consolidated by press and sinter techniques. Two-body abrasive wear resistance, of the composites worn against either SiC or garnet particles, was evaluated using a pin-on-drum apparatus. The wear behavior of the composites was correlated to the physical properties (e.g., microstructure, sintered density, hardness, strength) of the composites, and compared to the behavior of conventional cast adn wrought Ti and other alloys.

  4. Abrasive swivel assembly and method

    DOEpatents

    Hashish, Mohamed; Marvin, Mark

    1990-01-01

    An abrasive swivel assembly for providing a rotating, particle-laden fluid stream and, ultimately, a rotating particle-laden fluid jet is disclosed herein. This assembly includes a tubular arrangement for providing a particle-free stream of fluid, a swivel assembly for rotating a section of the tubular arrangement, and a tubular end section for introducing solid particles into the particle-free fluid stream at a point along the rotating tubular section, whereby to produce a particle-laden fluid stream. This last-mentioned stream can then be used in combination with a cooperating nozzle arrangement for providing a rotating particle-laden fluid jet. In an actual working embodiment, the fluid stream is of sufficiently high pressure so that the abrasive jet can be used as a cutting jet.

  5. Abrasive swivel assembly and method

    DOEpatents

    Hashish, Mohamed; Marvin, Mark

    1989-01-01

    An abrasive swivel assembly for providing a rotating, particle-laden fluid stream and, ultimately, a rotating particle-laden fluid jet is disclosed herein. This assembly includes a tubular arrangement for providing a particle-free stream of fluid, means for rotating a section of the tubular arrangement, and means for introducing solid particles into the particle-free fluid stream at a point along the rotating tubular section, whereby to produce a particle-laden fluid stream. This last-mentioned stream can then be used in combination with a cooperating nozzle arrangement for providing a rotating particle-laden fluid jet. In an actual working embodiment, the fluid stream is of sufficiently high pressure so that the abrasive jet can be used as a cutting jet.

  6. New data for aerosols generated by releases of pressurized powders and solutions in static air

    SciTech Connect

    Ballinger, M.Y.; Sutter, S.L.; Hodgson, W.H.

    1987-05-01

    Safety assessments and environmental impact statements for nuclear fuel cycle facilities require an estimate of potential airborne releases. Aerosols generated by accidents are being investigated by Pacific Northwest Laboratory to develop radioactive source-term estimation methods. Experiments measuring the mass airborne and particle size distribution of aerosols produced by pressurized releases were run. Carbon dioxide was used to pressurize uranine solutions to 50, 250, and 500 psig before release. The mass airborne from these experiments was higher than for comparable air-pressurized systems, but not as great as expected based on the amount of gas dissolved in the liquid and the volume of liquid ejected from the release equipment. Flashing sprays of uranine at 60, 125, and 240 psig produced a much larger source term than all other pressurized releases performed under this program. Low-pressure releases of depleted uranium dioxide at 9, 17.5, and 24.5 psig provided data in the energy region between 3-m spills and 50-psig pressurized releases.

  7. Characterization and dispersion of pollutant releases from the abrasive blasting of lead paint from steel bridges

    SciTech Connect

    Lee, M.; Rana, B.

    1999-07-01

    The characterization of airborne and spent material for abrasive blasting of steel paint was performed as part of the Environmental Impact Statement for Lead Paint Removal Operations on New York City Department of Transportation Bridges1. Laboratory tests were performed on painted steel components of the Williamsburg Bridge, to determine the sizes of particles typically released into the air as aerosol and onto the ground as bulk material, as a result of accidental releases from abrasive blasting operations. Two of the most commonly used abrasives for paint removal on steel structures, recyclable steel grit and expendable abrasives were subjected to the laboratory tests. The results of the tests were used to determine the percentage of existing paint and abrasive which becomes airborne and the resultant particle size distributions, which were employed in the air quality concentration and deposition modeling for the EIS. Particle size distributions of the airborne material indicated that the profiles of airborne lead and particulate matter have a mean particle size between 15 and 21 microns. Spent abrasives and paint chips that settle on the floor are larger in size with a mean diameter greater than 259 microns, although up to 6% of this material has a mean diameter less than 50 microns. The percentage of paint and expendable abrasives that become airborne as a result of abrasive blasting were estimated to be as high as 9.0 and 12.4%, respectively. Potential release rates were derived for total accumulation (duration of the project), annual, quarterly, 24-hour, and 1-hour time averaging periods for abrasives, lead, and other metals. Pollutant releases were simulated as individual sources at multiple release heights with the Environment Protection Agency's ISC3ST model for six representative bridges near potential places of public exposure.

  8. [Preparation of hard crown and bridge resin without PMMA powder (author's transl)].

    PubMed

    Nagata, K; Suzuki, S; Nakabayashi, N; Masuhara, E

    1979-01-01

    Elimination of PMMA powder to prepare better hard crown and bridge resin had been pointed out by the authors even though polyfunctional methacrylates were used. Application of hydrophobic coloidal silica instead of PMMA pearl with triethyleneglycol dimethacrylate and Bis-GMA was studied. Polyermization was carried out in the hot air stream at 120 degrees approximately 130 degrees C or in a pressure vessel at 4.5 kg/cm2 gauge, 100 degrees C. Mechanical properties, brinell hardness, compressive strength, an amount of water sorption, comparative average abrasion loss depth with those of PMMA, were measured. They were improved very much by this new system. PMID:221600

  9. A light-scattering study of Al2O3 abrasives of various grit sizes

    NASA Astrophysics Data System (ADS)

    Heinson, Yuli W.; Chakrabarti, Amitabha; Sorensen, Christopher M.

    2016-09-01

    We report light scattering phase function measurements for irregularly shaped Al2O3 abrasive powders of various grit sizes. Q-space analysis is applied to the angular scattering to reveal a forward scattering regime, Guinier regime, power law regime with quantifiable exponents, and an enhanced backscattering regime. The exponents of the power laws for Al2O3 abrasives decrease with increasing internal coupling parameter ρ ‧ , which is in agreement with previous observations for other irregular particles. Unlike other dust particles previously studied showing single power laws under Q-space analysis, the largest three abrasives, for which ρ ‧ ≳ 100 , showed a kink in the power law, which is possibly due to the higher degree of symmetry for the abrasives than for all the particles studied previously. Direct comparison of the 1200, 1000, and 800 grit abrasive scattering to scattering by corresponding spheres shows that the scatterings approximately coincide at the spherical particle qR ≃ ρ ‧ crossover point. Furthermore, the scattering at the maximum qR = 2 kR by the irregularly shaped abrasives is close to the geometric centers of the glories of the spheres.

  10. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  11. The effect of high dose on residual radicals in open air irradiated α-T UHMWPE resin powder

    NASA Astrophysics Data System (ADS)

    Mehmood, Malik S.; Shah, Jahan M.; Mishra, Sanjay R.; Walters, Benjamin M.

    2013-03-01

    Powder samples of UHMWPE (GUR 1020) containing 0.1 wt%. vitamin E (α-tocopherol, α-T) were irradiated at room temperature in air for doses of 30-kGy, 65-kGy or 100-kGy (60Co). After irradiation, they were stored at -78.5 °C (dry ice temperature) for 1 year and then opened to air at room temperature. Following the decay of the primary alkyl and allyl radicals (at room temperature in air), growth of the carbon-centered polyenyl R1 (-˙CH-[-CHCH-]m-, m≥3), and the oxygen-centered di- or tri-enyl R2 (-˙OCH-[-CHCH-]m-, m≤3) residual radicals were measured for 8 weeks. An X-band electron spin resonance (ESR) spectrometer was used for radical measurements. The initial relative radical concentrations (R2/R1) were found to be 10.13, 4.6 and 3.7 for the 65-kGy, 30-kGy and 100-kGy samples, respectively. R1 and R2 were both found to grow significantly in the 65-kGy sample while they grew only slightly in the 30-kGy and 100-kGy samples. In 65-kGy sample, R1 grew faster than R2 and the relative concentration R2/R1 was reduced from 10.13 to 2.9 for the 65-kGy sample while those for the 30-kGy and 100-kGy samples reduced only slightly, from 4.6 to 3.5 and 3.7 to 3.2, respectively. The behavior of the residual radicals can be explained by Raman spectroscopic data which suggest that the 65-kGy samples had a higher percentage of amorphous regions when compared to the 30-kGy or 100-kGy ones (21.7 compared to 15.7 or 17.9) and also suggest a lower percentage of interfacial regions (16.4 compared to 25.6 or 17.5) and a lower level of structural disorder (0.26 compared to 0.44 or 0.27).

  12. Abrasion-resistant coatings for plastic surfaces

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Hollahan, J. R.

    1976-01-01

    Optically clear composition of organosilicon compounds insulates plastic surfaces and protects them from abrasion. Plasma polymerization process produces superior uniformity and clarity than previous coating techniques.

  13. Abrasive drill for resilient materials

    NASA Technical Reports Server (NTRS)

    Koch, A. J.

    1981-01-01

    Resilient materials normally present problem in obtaining accurate and uniform hole size and position. Tool is fabricated from stiff metal rod such as tungsten or carbon steel that has diameter slightly smaller than required hole. Piercing/centering point is ground on one end of rod. Rod is then plasma-sprayed (flame-sprayed) with suitable hard abrasive coating. High-speed, slow-feed operation of tool is necessary for accurate holes, and this can be done with drill press, hard drill, or similar machines.

  14. Aluminum powder metallurgy processing

    NASA Astrophysics Data System (ADS)

    Flumerfelt, Joel Fredrick

    In recent years, the aluminum powder industry has expanded into non-aerospace applications. However, the alumina and aluminum hydroxide in the surface oxide film on aluminum powder require high cost powder processing routes. A driving force for this research is to broaden the knowledge base about aluminum powder metallurgy to provide ideas for fabricating low cost aluminum powder components. The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization commercial inert gas atomization and gas atomization reaction synthesis (GARS). The commercial atomization methods are bench marks of current aluminum powder technology. The GARS process is a laboratory scale inert gas atomization facility. A benefit of using pure aluminum powders is an unambiguous interpretation of the results without considering the effects of alloy elements. A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a

  15. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, Jr., Cressie E.; Gorin, Andrew H.; Seals, Roland D.

    1994-01-01

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  16. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

    1994-11-22

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  17. Ultrasonic Abrasive Removal Of EDM Recast

    NASA Technical Reports Server (NTRS)

    Mandel, Johnny L.; Jacobson, Marlowe S.

    1990-01-01

    Ultrasonic abrasive process removes layer of recast material generated during electrical-discharge machining (EDM) of damper pocket on turbine blade. Form-fitted tool vibrated ultrasonically in damper pocket from which material removed. Vibrations activate abrasive in pocket. Amount of material removed controlled precisely.

  18. Bendable Extension For Abrasive-Jet Cleaning

    NASA Technical Reports Server (NTRS)

    Mayer, Walter

    1989-01-01

    Hard-to-reach places cleaned more easily. Extension for abrasive-jet apparatus bent to provide controlled abrasive cleaning of walls in deep cavities or other hard-to-reach places. Designed for controlled removal of penetrant inspection dyes from inside castings, extension tube also used for such general grit-blasting work as removal of scratches.

  19. Corneal abrasions associated with pepper spray exposure.

    PubMed

    Brown, L; Takeuchi, D; Challoner, K

    2000-05-01

    Pepper spray containing oleoresin capsicum is used by law enforcement and the public as a form of nonlethal deterrent. Stimulated by the identification of a case of a corneal abrasion associated with pepper spray exposure, a descriptive retrospective review of a physician-maintained log of patients presenting to a jail ward emergency area over a 3-year period was performed. The objective was to give some quantification to the frequency with which an emergency physician could expect to see corneal abrasions associated with pepper spray exposure. Of 100 cases of pepper spray exposure identified, seven patients had sustained corneal abrasions. We conclude that corneal abrasions are not rare events when patients are exposed to pepper spray and that fluorescein staining and slit lamp or Wood's lamp examination should be performed on all exposed patients in whom corneal abrasions cannot be excluded on clinical grounds. PMID:10830682

  20. Three-dimensional DEM-CFD analysis of air-flow-induced detachment of API particles from carrier particles in dry powder inhalers.

    PubMed

    Yang, Jiecheng; Wu, Chuan-Yu; Adams, Michael

    2014-02-01

    Air flow and particle-particle/wall impacts are considered as two primary dispersion mechanisms for dry powder inhalers (DPIs). Hence, an understanding of these mechanisms is critical for the development of DPIs. In this study, a coupled DEM-CFD (discrete element method-computational fluid dynamics) is employed to investigate the influence of air flow on the dispersion performance of the carrier-based DPI formulations. A carrier-based agglomerate is initially formed and then dispersed in a uniformed air flow. It is found that air flow can drag API particles away from the carrier and those in the downstream air flow regions are prone to be dispersed. Furthermore, the influence of the air velocity and work of adhesion are also examined. It is shown that the dispersion number (i.e., the number of API particles detached from the carrier) increases with increasing air velocity, and decreases with increasing the work of adhesion, indicating that the DPI performance is controlled by the balance of the removal and adhesive forces. It is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance, which is governed by the ratio of the fluid drag force to the pull-off force. PMID:26579364

  1. Three-dimensional DEM–CFD analysis of air-flow-induced detachment of API particles from carrier particles in dry powder inhalers

    PubMed Central

    Yang, Jiecheng; Wu, Chuan-Yu; Adams, Michael

    2014-01-01

    Air flow and particle–particle/wall impacts are considered as two primary dispersion mechanisms for dry powder inhalers (DPIs). Hence, an understanding of these mechanisms is critical for the development of DPIs. In this study, a coupled DEM–CFD (discrete element method–computational fluid dynamics) is employed to investigate the influence of air flow on the dispersion performance of the carrier-based DPI formulations. A carrier-based agglomerate is initially formed and then dispersed in a uniformed air flow. It is found that air flow can drag API particles away from the carrier and those in the downstream air flow regions are prone to be dispersed. Furthermore, the influence of the air velocity and work of adhesion are also examined. It is shown that the dispersion number (i.e., the number of API particles detached from the carrier) increases with increasing air velocity, and decreases with increasing the work of adhesion, indicating that the DPI performance is controlled by the balance of the removal and adhesive forces. It is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance, which is governed by the ratio of the fluid drag force to the pull-off force. PMID:26579364

  2. Sliding and Abrasive Wear Behavior of WC-CoCr Coatings with Different Carbide Sizes

    NASA Astrophysics Data System (ADS)

    Thakur, Lalit; Arora, Navneet

    2013-02-01

    This study examines the sliding and abrasive wear behaviors of high-velocity oxy-fuel (HVOF)-sprayed WC-CoCr coatings with different WC grain sizes. The HVOF coating deposition was assisted by in-flight particle temperature and velocity measurement system. The powder feedstocks and their corresponding coatings were characterized by means of XRD and Field Emission Scanning Electron Microscope analysis. Hardness, porosity, and indentation fracture toughness of these coatings were calculated and compared with each other. Sliding wear resistance of these coatings was calculated using pin-on-disk tribometer (ASTM G99-90). The two-body abrasion was quantified by sliding the samples over silicon carbide (SiC) abrasive paper bonded to a rotating flat disk of auto-polisher. The mechanism of materials' removal in both the sliding and abrasive wears was studied and discussed on microstructural investigations. It was observed that fine grain WC-CoCr cermet coating exhibits higher sliding and abrasive wear resistances as compared with conventional cermet coating.

  3. The abrasion and impact-abrasion behavior of austempered ductile irons

    SciTech Connect

    Hawk, Jeffrey A.; Dogan, Omer N.; Lerner, Y.S.

    1998-01-01

    Austempering of ductile irons has led to a new class of irons, Austempered Ductile Irons (ADIs), with improved mechanical strength and fracture toughness lacking in gray cast irons. Laboratory wear tests have been used to evaluate the abrasive and impact-abrasive wear behavior of a suite of ADIs. The use of high-stress, two-body abrasion, low-stress, three-body abrasion, and impact-abrasion tests provides a clear picture of the abrasive wear behavior of the ADIs and the mechanisms of material removal. When combined with hardness measurements, fracture toughness and a knowledge of the microstructure of the ADIs, the overall performance can be assessed relative to more wear resistant materials such as martensitic steels and high-chromium white cast irons

  4. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Abrasive device and accessories. 872.6010...

  5. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Abrasive device and accessories. 872.6010...

  6. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Abrasive device and accessories. 872.6010...

  7. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  8. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  9. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  10. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  11. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  12. The measurement of abrasive particles velocities in the process of abrasive water jet generation

    NASA Astrophysics Data System (ADS)

    Zeleňák, Michal; Foldyna, Josef; Říha, Zdeněk

    2014-08-01

    An optimization of the design of the abrasive cutting head using the numerical simulation requires gathering as much information about processes occurring in the cutting head as possible. Detailed knowledge of velocities of abrasive particles in the process of abrasive water jet generation is vital for the verification of the numerical model. A method of measurement of abrasive particles at the exit of focusing tube using the FPIV technique was proposed and preliminary tests are described in the paper. Results of analysis of measured velocity fields are presented in the paper.

  13. New iron-based SiC spherical composite magnetic abrasive for magnetic abrasive finishing

    NASA Astrophysics Data System (ADS)

    Zhang, Guixiang; Zhao, Yugang; Zhao, Dongbiao; Zuo, Dunwen; Yin, Fengshi

    2013-03-01

    SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness( R a) of the plate worked is rapidly reduced to 0.051 μm from an initial value of 0.372 μm within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid

  14. Abrasion by aeolian particles: Earth and Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; White, B. R.; Pollack, J. B.; Marshall, J.; Krinsley, D.

    1984-01-01

    Estimation of the rate of aeolian abrasion of rocks on Mars requires knowledge of: (1) particle flux, (2) susceptibilities to abrasion of various rocks, and (3) wind frequencies on Mars. Fluxes and susceptibilities for a wide range of conditions were obtained in the laboratory and combined with wind data from the Viking meteorology experiment. Assuming an abundant supply of sand-sized particles, estimated rates range up to 2.1 x 10 to the minus 2 power cm of abrasion per year in the vicinity of Viking Lander 1. This rate is orders of magnitude too great to be in agreement with the inferred age of the surface based on models of impact crater flux. The discrepancy in the estimated rate of abrasion and the presumed old age of the surface cannot be explained easily by changes in climate or exhumation of ancient surfaces. The primary reason is thought to be related to the agents of abrasion. At least some sand-sized (approx. 100 micrometers) grains appear to be present, as inferred from both lander and orbiter observations. High rates of abrasion occur for all experimental cases involving sands of quartz, basalt, or ash. However, previous studies have shown that sand is quickly comminuted to silt- and clay-sized grains in the martian aeolian regime. Experiments also show that these fine grains are electrostatically charged and bond together as sand-sized aggregates. Laboratory simulations of wind abrasion involving aggregates show that at impact velocities capable of destroying sand, aggregates from a protective veneer on the target surface and can give rise to extremely low abrasion rates.

  15. Microstructure and abrasion resistance of plasma sprayed titania coatings

    NASA Astrophysics Data System (ADS)

    Ctibor, P.; Neufuss, K.; Chraska, P.

    2006-12-01

    Agglomerated titania nanopowder and a “classical” titania were sprayed by the high throughput water-stabilized plasma (WSP) and thoroughly compared. Optical microscopy with image analysis as well as mercury intrusion porosimetry were used for quantification of porosity. Results indicate that the “nano” coatings in general exhibit finer pores than coatings of the “conventional” micron-sized powders. Mechanical properties such as Vickers microhardness and slurry abrasion response were measured and linked to the structural investigation. Impact of the variation in the slurry composition on wear resistance of tested coatings and on character of the wear damage is discussed. The overall results, however, suggest that the “nano” coatings properties are better only for carefully selected sets of spraying parameters, which seem to have a very important impact.

  16. Abrasive wear of advanced structural materials

    NASA Astrophysics Data System (ADS)

    Lee, Gun-Young

    Wear of advanced structural materials, namely composites and ceramics, in abrasion has been examined in the present study. A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of reinforcement is estimated by modeling three primary wear mechanisms, specifically plowing, cracking at the matrix/reinforcement interface or in the reinforcement, and particle removal. Critical variables describing the role of the reinforcement, such as the relative size, fracture toughness, and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on-drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy-matrix composite material. In addition, the effects of post heat-treatment on the wear behavior of toughened silicon carbide (ABC-SiC) are investigated by characterizing the role of the microstructures introduced during the post annealing processes. When the annealing temperature is above 1300°C, an aluminum rich secondary phase (nano-precipitate) forms and grows inside the SiC grains. This toughened silicon carbide (ABC-SiC), annealed at temperatures ranging from 0 to 1600°C, is subjected to two- and three-body abrasions with different sizes of abrasives (3˜70 mum). The test results exhibit that the effect of nano-precipitates on wear resistance of post-annealed ABC-SiC is restricted to the abrasion with fine abrasives (3 mum), since nano-precipitates, in the range from 4 nm at 1300°C to 25 nm at 1600°C, are comparable in dimension

  17. Design and in vitro performance testing of multiple air classifier technology in a new disposable inhaler concept (Twincer) for high powder doses.

    PubMed

    de Boer, Anne H; Hagedoorn, Paul; Westerman, Elsbeth M; Le Brun, Paul P H; Heijerman, Harry G M; Frijlink, Henderik W

    2006-06-01

    Dry powder inhalation of antibiotics in cystic fibrosis (CF) therapy may be a valuable alternative for wet nebulisation, because it saves time and it improves lung deposition. In this study, it is shown that the use of multiple air classifier technology enables effective dispersion of large amounts of micronised powder (up to 25mg). X(50)-values of the aerosol from laser diffraction analysis obtained with the Twincer disposable inhaler concept (containing multiple air classifier technology) are practically the same as that for the pure drug in the range of dose weights between 0 and 25mg. Only for the highest dose weights, a minor fraction (5-7.5%) of small agglomerates (5-15microm) is released from the inhaler. Moreover, the size distribution of the aerosol is practically the same at 1 and 4kPa. Cascade impactor results confirm the good performance of the multiple classifier concept. Unprocessed micronised particles or soft spherical agglomerates can be used, and special particle engineering processes are not necessary. Only a minor fraction of coarse sweeper crystals in the formulation is desired to reduce the total inhaler losses for colistin sulfomethate to less than 5-6% at 4kPa. The classifiers can be designed to retain these crystals with more than 95% efficiency. PMID:16650739

  18. A rotary-airlock valve resists abrasive mixtures

    SciTech Connect

    Not Available

    1993-03-01

    Hill and Griffith (H and G, Cincinnati, Ohio) is a leading supplier of custom-blended additives to founderies. Thousands of tons of clay and carbon blends such as bentonite, gilsonite and pulverized coal, pass through the company's rotary-airlock feeding system each month. H and G's original rotary valves had cylinders lined with chrome, and closed-end rotors with tips made from nickel-chromium alloys. These valves remained in service for a maximum of only three months each. During that time, the abrasive mixtures passing through the valves virtually eroded them, increasing tolerances and causing significant air leakage. The leaks caused the pneumatic line to plug up, reducing the velocity of the line below the minimum level needed to carry any material. To overcome the leakage, a second blower was added to the system. This unit supplied an additional 40 brake hp to the pneumatic-conveying line. With constant maintenance of the valve and the continuous operation of both blowers, H and G was able to extend the valve's life by nine months. After 20 years of trying valves with various configuration, H and G installed a Smoot Type 6 rotary-airlock valve in September of 1985. The new valve's internals were made from abrasion-resistant grades of NiHard and Stellite. This combination of alloys prolonged the active life of the valve by improving its abrasion resistance. During its first year, the Smoot valve did not break down, leak air or require use of the secondary blower. After its first year of service no wear was found on the valve's internal surfaces. Another mechanical analysis was performed in 1991, after five additional years of valve operation. The valve, which had now handled more than 250,000 tons of product, showed minimal wear. H and G's capital costs had been reduced from 25[cents]/ton to 3[cents]/ton by the new valve.

  19. PAGMan - propelled abrasive grit to manage weeds in soybean and corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New tools for controlling weeds would be useful for soybean and corn production in organic systems or in systems in which weeds developed resistance to multiple herbicides. Here we report on two developments: (i) the safety to soybean seedlings of using air-propelled abrasive grit (PAG) for managing...

  20. Microstructural effects in abrasive wear. Quarterly progress report, June 1981-January 1982

    SciTech Connect

    Kosel, T.H.; Rao, C.M.; Fernandes, M.T.; Fiore, N.F.

    1982-02-24

    This report describes research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials, including high-Cr white irons and powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling, and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion, and transfer applications. Recent work has concentrated on analysis of results. The many detailed observations obtained in the work on scratch test simulations of abrasive wear mechanisms have been summarized in drafts of three papers. The first, a study of abrasive wear mechanisms using diamond and alumina scratch tests, was included as an appendix to Quarterly Report 16/17 and has been accepted for publication in the journal Wear. Revision of the other two papers is in progress. Two papers representing our analysis of results are included as appendices to this report. The first, abrasion in multiphase alloys, was presented at the NACE conference on corrosion-erosion-wear of materials at Berkeley, California in January 1982, and will be published in the proceedings. The second, on a deformation-induced phase transformation during abrasive wear of Co-base alloys, is being submitted for publication in Metallurgical Transactions. In addition, work on the gouging abrasion resistance of the previously tested high Cr-Mo white cast irons is completed. The abstract of a short paper on the results is included as an appendix. (Note: since the appendices are, or will be, available in the open literature they have been removed from the report.)

  1. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  2. Abrasion resistance of medical glove materials.

    PubMed

    Walsh, Donna L; Schwerin, Matthew R; Kisielewski, Richard W; Kotz, Richard M; Chaput, Maria P; Varney, George W; To, Theresa M

    2004-01-15

    Due to the increasing demand for nonlatex medical gloves in the health-care community, there is a need to assess the durability of alternative glove materials. This study examines durability characteristics of various glove materials by abrasion resistance testing. Natural rubber latex (latex), polyvinyl chloride (vinyl), acrylonitrile butadiene (nitrile), polychloroprene (neoprene), and a styrene-ethylene/butylene-styrene block copolymer (SEBS) were tested. All test specimens, with the exception of the vinyl, were obtained from surgical gloves. Unaged out-of-the-box specimens as well as those subjected to various degrees of artificial aging were included in the study. After the abrasion sequence, the barrier integrity of the material was assessed through the use of a static leak test. Other traditional tests performed on these materials were viral penetration to validate the abrasion data and tear testing for comparative purposes. The results indicate that specific glove-material performance is dependent upon the particular test under consideration. Most notably, abrasion, even in controlled nonsevere conditions, may compromise to varying degrees the barrier integrity of latex, vinyl, SEBS, nitrile, and neoprene glove materials. However, as evidenced by the results of testing three brands of neoprene gloves, the abrasion resistance of any one glove material may be significantly affected by variations in production processes. PMID:14689500

  3. Mask materials for powder blasting

    NASA Astrophysics Data System (ADS)

    Wensink, Henk; Jansen, Henri V.; Berenschot, J. W.; Elwenspoek, Miko C.

    2000-06-01

    Powder blasting, or abrasive jet machining (AJM), is a technique in which a particle jet is directed towards a target for mechanical material removal. It is a fast, cheap and accurate directional etch technique for brittle materials such as glass, silicon and ceramics. The particle jet (which expands to about 1 cm in diameter) can be optimized for etching, while the mask defines the small and complex structures. The quality of the mask influences the performance of powder blasting. In this study we tested and compared several mask types and added a new one: electroplated copper. The latter combines a highly resistant mask material for powder blasting with the high-resolution capabilities of lithography, which makes it possible to obtain an accurate pattern transfer and small feature sizes (<50 µm).

  4. CFD Based Erosion Modelling of Abrasive Waterjet Nozzle using Discrete Phase Method

    NASA Astrophysics Data System (ADS)

    Hakim Kamarudin, Naqib; Prasada Rao, A. K.; Azhari, Azmir

    2016-02-01

    In Abrasive Waterjet (AWJ) machining, the nozzle is the most critical component that influences the performance, precision and economy. Exposure to a high speed jet and abrasives makes it susceptible to wear erosion which requires for frequent replacement. The present works attempts to simulate the erosion of the nozzle wall using computational fluid dynamics. The erosion rate of the nozzle was simulated under different operating conditions. The simulation was carried out in several steps which is flow modelling, particle tracking and erosion rate calculation. Discrete Phase Method (DPM) and K-ε turbulence model was used for the simulation. Result shows that different operating conditions affect the erosion rate as well as the flow interaction of water, air and abrasives. The simulation results correlates well with past work.

  5. An investigation into magnetic electrolytic abrasive turning

    NASA Astrophysics Data System (ADS)

    Mahdy, M. A. M.; Ismaeial, A. L.; Aly, F. F.

    2013-07-01

    The magnetic electrolytic abrasive turning (MEAT) process as a non-traditional machining is used to obtain surface finishing like mirror. MEAT provides one of the best alternatives for producing complex shapes with good finish in advanced materials used in aircraft and aerospace industries. The improvement of machining accuracy of MEAT continues to be a major challenge for modern industry. MEAT is a hybrid machining which combines two or more processes to remove material. The present research focuses on the development of precision electrochemical turning (ECT) under the effects of magnetic field and abrasives. The effect of magnetic flux density, electrochemical conditions and abrasive parameters on finishing efficiency and surface roughness are investigated. An empirical relationship is deduced.

  6. The Effect of Pleural Abrasion on the Treatment of Primary Spontaneous Pneumothorax: A Systematic Review of Randomized Controlled Trials

    PubMed Central

    Ming, Mo-yu; Cai, Shuang-qi; Chen, Yi-Qiang

    2015-01-01

    Background Pleural abrasion has been widely used to control the recurrence of primary spontaneous pneumothorax (PSP). However, controversy still exists regarding the advantages and disadvantages of pleural abrasion compared with other interventions in preventing the recurrence of PSP. Methods The PubMed, Embase, and Cochrane Central Register of Controlled Trials databases were searched up to December 15, 2014 to identify randomized controlled trials (RCTs) that compared the effects of pleural abrasion with those of other interventions in the treatment of PSP. The study outcomes included the PSP recurrence rate and the occurrence rate of adverse effects. Results Mechanical pleural abrasion and apical pleurectomy after thoracoscopic stapled bullectomy exhibited similarly persistent postoperative air leak occurrence rates (p = 0.978) and 1-year PSP recurrence rates (p = 0.821), whereas pleural abrasion led to reduced residual chest pain and discomfort (p = 0.001) and a smaller rate of hemothorax (p = 0.036) than did apical pleurectomy. However, the addition of minocycline pleurodesis to pleural abrasion did not reduce the pneumothorax recurrence rate compared with apical pleurectomy (3.8% for both procedures) but was associated with fewer complications. There was no statistical difference in the pneumothorax recurrence rate between mechanical pleural abrasion and chemical pleurodesis with minocycline on either an intention-to-treat basis (4 of 42 versus 0 of 42, p = 0.12; Fisher exact test) or after exclusions (2 of 40 versus 0 of 42, p = 0.24; Fisher exact test). Pleural abrasion plus minocycline pleurodesis also did not reduce the pneumothorax recurrence rate compared with pleural abrasion alone (p = 0.055). Moreover, pleural abrasion plus minocycline pleurodesis was associated with more intense acute chest pain. The postoperative overall recurrence rate in patients who underwent staple line coverage with absorbable cellulose mesh and fibrin glue was similar to that

  7. Vacuum powder injector and method of impregnating fiber with powder

    NASA Technical Reports Server (NTRS)

    Working, Dennis C. (Inventor)

    1993-01-01

    A method and apparatus uniformly impregnate stranded material with dry powder such as low solubility, high melt flow polymer powder to produce, for example, composite prepregs. The stranded material is expanded in an impregnation chamber by an influx of air so that the powder, which may enter through the same inlet as the air, penetrates to the center of the stranded material. The stranded material then is contracted for holding the powder therein. The stranded material and powder may be pulled through the impregnation chamber in the same direction by vacuum. Larger particles of powder which do not fully penetrate the stranded material may be combed into the stranded material and powder which does not impregnate the stranded material may be collected and reused.

  8. Microstructural effects in abrasive wear. Quarterly progress report, January 1-June 1, 1980

    SciTech Connect

    Fiore, N.F.; Kosel, T.H.; Channagiri, M.; Desai, V.; Fulcher, J.; Shetty, H.R.

    1980-06-01

    Research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials is described including high-Cr white irons and experimental Co-base and Ni-base powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion and transfer applications. Research has concentrated on the investigation of wear in Co-base PM alloys No. 19 and No. 6, which have been sintered to provide different carbide sizes at the same volume fraction in each respective alloy. Low-stress abrasion tests using Al/sub 2/O/sub 3/ abrasive have been completed on Alloy No. 19 and the results show a monotonic decrease in wear rate with increasing size. A series of single-point scratch test simulations of abrasive wear mechanisms has been initiated, and these tests provide valuable insights into material removal processes in the Co-base alloys.

  9. Abrasive Wear Behaviour of COPPER-SiC and COPPER-SiO2 Composites

    NASA Astrophysics Data System (ADS)

    Umale, Tejas; Singh, Amarjit; Reddy, Y.; Khatitrkar, R. K.; Sapate, S. G.

    The present paper reports abrasive wear behaviour of copper matrix composites reinforced with silicon carbide and silica particles. Copper - SiC (12%) and Copper-SiO2 (9%) composites were prepared by powder metallurgical technique. Metallography, image analysis and hardness studies were carried out on copper composites. The abrasive wear experiments were carried out using pin on disc apparatus. The effect of sliding distance and load was studied on Copper - SiC (12%) and Copper-SiO2 (9%) composites. The abrasive wear volume loss increased with sliding distance in both the composites although the magnitude of increase was different in each case. Copper - SiC (12%) composites exhibited relatively better abrasion resistance as compared to and Copper-SiO2 (9%) composites. The abraded surfaces were observed under scanning electron microscope to study the morphology of abraded surfaces and operating wear mechanism. The analysis of wear debris particles was also carried out to substantiate the findings of the investigation.

  10. Parametric Study to Correlate the Applied Factors and Abrasive Wear Resistance of HVOF Coating

    NASA Astrophysics Data System (ADS)

    Sharma, Satpal

    2012-12-01

    Co-Ni-base powder was modified with the addition of CeO2 to study the effect of CeO2 addition on microstructure, hardness, and abrasive wear behavior of the unmodified (without CeO2) and modified (with CeO2) HVOF sprayed coatings. To investigate the abrasive wear behavior of coatings statistical response surface methodology (RSM) with four factors such as load, abrasive size, sliding distance, and temperature with three levels of each factor were used. Analysis of variance (ANOVA) was carried out to determine the significant factors and their interactions. Thus abrasive wear model was developed in terms of main factors and their significant interactions. The validity of the model was evaluated by conducting experiments under different wear conditions. A comparison of modeled and experimental results showed 2-8% error. The wear resistance of coatings increased with the addition of CeO2. This is due to increase in hardness with the addition of CeO2 in Co-Ni-base coatings.

  11. Corneal Abrasions and Corneal Foreign Bodies.

    PubMed

    Ahmed, Faheem; House, Robert James; Feldman, Brad Hal

    2015-09-01

    Corneal abrasions and corneal foreign bodies are frequently encountered ophthalmological injuries that are commonly diagnosed and managed by primary care physicians. The clinical course of a corneal epithelial defect can range from a relatively benign self-healing abrasion to a potentially sight-threatening complication such as a corneal ulcer, recurrent erosion, or traumatic iritis. A detailed clinical history regarding risk factors and exposure, along with a thorough slit lamp examination with fluorescein dye are essential for proper diagnosis and treatment, as well as to rule out penetrating globe injuries. Referral to an ophthalmologist is recommended in difficult cases or if other injuries are suspected. PMID:26319343

  12. Friction and abrasion of elastomeric materials

    NASA Technical Reports Server (NTRS)

    Gent, A. N.

    1975-01-01

    An abrasion apparatus is described. Experimental measurements are reported for four representative elastomeric materials, including a typical high-quality tire tread material and a possible replacement material for aircraft tire treads based on transpolypentenamer (TPPR). Measurements are carried out at different levels of frictional work input, corresponding to different severities of wear, and at both ambient temperature and at 100 C. Results indicate the marked superiority in abrasion resistance of the material based on TPPR, especially at 100 C, in comparison with the other materials examined.

  13. Universal scaling relations for pebble abrasion

    NASA Astrophysics Data System (ADS)

    Litwin, K. L.; Jerolmack, D. J.

    2012-12-01

    The process of abrasion of gravel in bed load transport results from particle-to-particle collisions, where the energy involved is sufficient to cause chipping and spallation but not fragmentation of parent grains. The removed rock material is not infinitesimal; daughter products as large as coarse sand can be produced. Although previous work has shown that lithology, grain shape, and energy of collision are contributing factors that control abrasion rates of river-bed material, little is known regarding the relationship between these factors and diminution rates. Here we explicitly isolate and investigate how these three factors influence rates of abrasion and the size distribution of daughter products, with laboratory experiments. The apparatus is a double pendulum (Newton's cradle) that produces well-controlled binary collisions. A high-speed camera precisely measures collision energy, while mass of parent rocks. and the size and shape distributions of daughter products, are measured periodically. We examined abrasion of initially square-cut 'rocks' as they underwent successive collisions in the binary collision apparatus. We have examined mass loss rate for varied lithologies, and observe a similar power-law relationship between impact energy and mass abraded. When normalized by sensible material properties, mass loss curves for all materials collapse onto a single curve, suggesting that the underlying mechanics of abrasion for different materials are the same. The relationship does not display the linear trend expected from pure energetics, and we suggest that this is a shape effect as protruding - and hence easily eroded - corners are worn away. Analysis of daughter-product particle size distributions for different lithology fragments - including natural rocks and also bricks - show the same functional form. Surprisingly, it is the power-law relation expected for brittle materials undergoing fragmentation. This suggests that brittle fracture theory also

  14. Quadrupole lamp furnace for high temperature (up to 2050 K) synchrotron powder x-ray diffraction studies in air in reflection geometry

    SciTech Connect

    Sarin, P.; Yoon, W.; Jurkschat, K.; Zschack, P.; Kriven, W. M.

    2006-09-15

    A four-lamp thermal image furnace has been developed to conduct high temperature x-ray diffraction in reflection geometry on oxide ceramic powder samples in air at temperatures {<=}2050 K using synchrotron radiation. A refractory crucible made of Pt20%Rh alloy was used as a specimen holder. A material with well characterized lattice expansion properties was used as an internal crystallographic thermometer to determine the specimen temperature and displacement. The performance of the apparatus was verified by measurement of the thermal expansion properties of CeO{sub 2}, MgO, and Pt which were found to be within {+-}3% of the acceptable values. The advantages, limitations, and important considerations of the instrument developed are discussed.

  15. Quadrupole lamp furnace for high temperature (up to 2050 K) synchrotron powder x-ray diffraction studies in air in reflection geometry.

    SciTech Connect

    Sarin, P.; Yoon, W.; Jurkschat, K.; Zschack, P.; Kriven, W. M.; Univ. of Illinois; Frederick-Seitz Materials Research Lab.

    2006-09-01

    A four-lamp thermal image furnace has been developed to conduct high temperature x-ray diffraction in reflection geometry on oxide ceramic powder samples in air at temperatures {le} 2050 K using synchrotron radiation. A refractory crucible made of Pt20%Rh alloy was used as a specimen holder. A material with well characterized lattice expansion properties was used as an internal crystallographic thermometer to determine the specimen temperature and displacement. The performance of the apparatus was verified by measurement of the thermal expansion properties of CeO{sub 2}, MgO, and Pt which were found to be within {+-} 3% of the acceptable values. The advantages, limitations, and important considerations of the instrument developed are discussed.

  16. Recent progress of abrasion-resistant materials: learning from nature.

    PubMed

    Meng, Jingxin; Zhang, Pengchao; Wang, Shutao

    2016-01-21

    Abrasion-resistant materials have attracted great attention for their broad applications in industry, biomedicine and military. However, the development of abrasion-resistant materials that have with unique features such as being lightweight and flexible remains a great challenge in order to satisfy unmet demands. The outstanding performance of natural abrasion-resistant materials motivates the development of new bio-inspired abrasion-resistant materials. This review summarizes the recent progress in the investigation of natural abrasion-resistant materials to explore their general design principles (i.e., the correlation between chemical components and structural features). Following natural design principles, several artificial abrasion-resistant materials have shown unique abrasion-resistant properties. The potential challenges in the future and possible solutions for designing bio-inspired abrasion-resistant materials are also briefly discussed. PMID:26335377

  17. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... exceeded. (j) All employees using abrasive wheels shall be protected by eye protection equipment in accordance with the requirements of subpart I of this part except when adequate eye protection is afforded by eye shields which are permanently attached to the bench or floor stand....

  18. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  19. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  20. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  1. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  2. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... spindle speed under all conditions of normal grinding. The rated maximum speed of the wheel shall not be...) Floor stand and bench mounted abrasive wheels used for external grinding shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and sides...

  3. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... spindle speed under all conditions of normal grinding. The rated maximum speed of the wheel shall not be...) Floor stand and bench mounted abrasive wheels used for external grinding shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and sides...

  4. Evaluation and Treatment of Perioperative Corneal Abrasions

    PubMed Central

    Segal, Kira L.; Fleischut, Peter M.; Kim, Charles; Levine, Ben; Faggiani, Susan L.; Banerjee, Samprit; Gadalla, Farida; Lelli, Gary J.

    2014-01-01

    Purpose. To evaluate perioperative risk factors for corneal abrasion (CA) and to determine current care for perioperative CA in a tertiary care setting. Methods. Hospital-based, cross-sectional study. In Operating Room and Post-Anesthesia Care Units patients, a comparison of cases and controls was evaluated to elucidate risk factors, time to treatment, and most common treatments prescribed for corneal abrasions. Results. 86 cases of corneal abrasion and 89 controls were identified from the 78,542 surgical procedures performed over 2 years. Statistically significant risk factors were age (P = 0.0037), general anesthesia (P < 0.001), greater average estimated blood loss (P < 0.001), eyes taped during surgery (P < 0.001), prone position (P < 0.001), trendelenburg position (P < 0.001), and supplemental oxygen en route to and in the Post-Anesthesia Care Units (P < 0.001). Average time to complaint was 129 minutes. 94% of cases had an inpatient ophthalmology consult, with an average time to consult of 164 minutes. The most common treatment was artificial tears alone (40%), followed by combination treatment of antibiotic ointment and artificial tears (35.3%). Conclusions. Trendelenburg positioning is a novel risk factor for CA. Diagnosis and treatment of perioperative corneal abrasions by an ophthalmologist typically require three hours in the tertiary care setting. PMID:24672709

  5. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  6. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Abrasive wheels. 1915.134 Section 1915.134 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Tools and Related...

  7. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Abrasive wheels. 1915.134 Section 1915.134 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Tools and Related...

  8. Dust transport and abrasion assessment within simulated standing vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop residues are useful in protecting the top soil from depletion and abrasion due to wind erosion. A wind tunnel study was done to measure sand transport and abrasion energies within the simulated artificial standing vegetation. Wind profiles, relative abrasion energies and rates of sand dischar...

  9. Relationship between abrasive wear and microstructure of composite resins.

    PubMed

    Draughn, R A; Harrison, A

    1978-08-01

    The in vitro abrasion resistance of seven commercial composite resin restorative materials has been measured. Analysis of the composite microstructures shows that abrasion rates are dependent upon the size, hardness, and volume fraction of particles in the material. The most abrasion-resistant composites contain a high volume fraction of large, hard particles. PMID:278840

  10. Technique for determination of accurate heat capacities of volatile, powdered, or air-sensitive samples using relaxation calorimetry

    NASA Astrophysics Data System (ADS)

    Marriott, Robert A.; Stancescu, Maria; Kennedy, Catherine A.; White, Mary Anne

    2006-09-01

    We introduce a four-step technique for the accurate determination of the heat capacity of volatile or air-sensitive samples using relaxation calorimetry. The samples are encapsulated in a hermetically sealed differential scanning calorimetry pan, in which there is an internal layer of Apiezon N grease to assist thermal relaxation. Using the Quantum Design physical property measurement system to investigate benzoic acid and copper standards, we find that this method can lead to heat capacity determinations accurate to ±2% over the temperature range of 1-300K, even for very small samples (e.g., <10mg and contributing ca. 20% to the total heat capacity).

  11. Wheel Abrasion Experiment Conducted on Mars

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.

    1998-01-01

    Sojourner rover showing Lewis' wheel abrasion experiment. The Mars Pathfinder spacecraft soft-landed on Mars on July 4, 1997. Among the many experiments on its small Sojourner rover are three technology experiments from the NASA Lewis Research Center, including the Wheel Abrasion Experiment (WAE). The WAE was designed, built, delivered, and operated on Mars by a team of engineers and scientists from Lewis' Photovoltaics and Space Environments Branch. This experiment collected data to assess wheel surface wear on the Sojourner. It used a specially designed rover wheel, with thin films (200 to 1000 angstroms) of aluminum, nickel, and platinum deposited on black, anodized aluminum strips attached to the rover's right center wheel. As the wheel spun in the Martian soil, a photovoltaic sensor monitored changes in film reflectivity. These changes indicated abrasion of the metal films by Martian surface material. Rolling wear data were accumulated by the WAE. Also, at frequent intervals, all the rover wheels, except the WAE test wheel, were locked to hold the rover stationary while the test wheel alone was spun and dug into the Martian regolith. These tests created wear conditions more severe than simple rolling. The WAE will contribute substantially to our knowledge of Martian surface characteristics. Marked abrasion would indicate a surface composed of hard, possibly sharply edged grains, whereas lack of abrasion would suggest a somewhat softer surface. WAE results will be correlated with ground simulations to determine which terrestrial materials behave most like those on Mars. This knowledge will enable a deeper understanding of erosion processes on Mars and the role they play in Martian surface evolution. Preliminary results show that electrostatic charging of the rover wheels sometimes caused dust to accumulate on the WAE wheel, making interpretation of the reflectance data problematic. If electrostatic charging is the mechanism for dust attraction, this indicates

  12. Abrasion resistance of linings in filament wound composite pipe

    SciTech Connect

    Hall, S.C.

    1999-07-01

    Fiberglass filament wound composite pipe has numerous industrial applications including transportation of petroleum and natural gas. Its corrosion resistance is well known but it can be susceptible to abrasion and erosion when it is used to transport slurries or dry gas containing sand particles. However, composite pipe can be manufactured integrally with abrasion resistant linings which protect the pipe from abrasion and erosion and increase its life. Laboratory investigations were performed to determine the effect of abrasive flows through polyurea-lined and unlined glass-reinforced epoxy (GRE) pipe, ultra-high molecular weight (UHMW) polyethylene (PE) pipe, and unlined steel pipe. Results are provided for the abrasion resistance, chemical resistance, adhesion strength, elongation, tensile strength, impact resistance and hardness of selected linings. The abrasion resistance of polyurea-lined composite pipe proved to be almost as resistant to abrasion and erosion as unlined steel pipe without the electrochemical corrosion associated with steel pipe.

  13. Abrasion-Resistant Technology and its Prospect for CFB Boilers

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Li, Y. J.; Wang, L. J.; Liu, S. H.; Dou, Q. R.

    In recent years, CFB boilers (CFBB) have been widely used in the commercial power plants due to its environmental benefits, high combustion efficiency, wide coal flexibility, and some other advantages. At the same time, the abrasion problem, the greatest weakness of this kind of boiler, has been gradually exposed in its application process. The abrasion, particularly on key parts such as the heating surface of water-cooled wall, furnace corners, separator entrance, seriously restricts the long-period operation ability of the CFBB. This article discusses current development status for various abrasion resistant refractory materials used in a CFBB. Some comments are provided for developing new high-performance abrasion resistant refractory materials and rapid-repaired materials according to the abrasion principle and the abrasion on different parts, as well as the economical and environmental requirements for the material. The abrasion solution and operation period of CFBB can be better improved given realization.

  14. Liquid abrasive pressure pot scoping tests report

    SciTech Connect

    Archibald, K.E.

    1996-01-01

    The primary initiatives of the LITCO Decontamination Development group at the Idaho Chemical Process Plant (ICPP) are the development of methods to eliminate the use of sodium bearing decontamination chemicals and minimization of the amount of secondary waste generated during decontamination activities. In July of 1994, a Commerce Business Daily (CBD) announcement was issued by the INEL to determine commercial interest in the development of an in-situ liquid abrasive grit blasting system. As a result of the CBD announcement, Klieber & Schulz issued an Expression of Interest letter which stated they would be interested in testing a prototype Liquid Abrasive Pressure Pot (LAPP). LITCO`s Decontamination group and Kleiber & Schulz entered into a Cooperative Research and Development Agreement (CRADA) in which the Decontamination Development group tested the prototype LAPP in a non-radioactive hot cell mockup. Test results are provided.

  15. Sliding and abrasive wear resistance of thermal-sprayed WC-CO coatings

    NASA Astrophysics Data System (ADS)

    Qiao, Yunfei; Liu, Yourong; Fischer, Traugott E.

    2001-03-01

    We studied the resistance of the coatings to abrasive and unlubricated sliding wear of 40 WC/Co coatings applied by high velocity oxygen fuel (HVOF), high-energy plasma spray (HEPS), and high velocity plasma spray (HVPS), using commercial and nanostructured experimental powders. The hardness of the coatings varies from 3 to 13 GPA, which is much lower than that of sintered samples (10 to 23 GPA) because of the porosity of the coatings. Phase analysis by x-ray diffraction revealed various amounts of decarburization in the coatings, some of which contain WC, W2C, W, and η phase. The abrasive and sliding wear resistance is limited by the hardness of the samples. For a given hardness, the wear resistance is lowered by decarburization, which produces a hard but brittle phase. Nanocarb powders have the shape of thin-walled hollow spheres that heat up rapidly in the gun and are more prone to decarburization than commercial materials. The work shows that, in order to obtain the performance of nanostructured coatings, the powder and spray techniques must be modified.

  16. Loose abrasive slurries for optical glass lapping

    SciTech Connect

    Neauport, Jerome; Destribats, Julie; Maunier, Cedric; Ambard, Chrystel; Cormont, Philippe; Pintault, B.; Rondeau, Olivier

    2010-10-20

    Loose abrasive lapping is widely used to prepare optical glass before its final polishing. We carried out a comparison of 20 different slurries from four different vendors. Slurry particle sizes and morphologies were measured. Fused silica samples were lapped with these different slurries on a single side polishing machine and characterized in terms of surface roughness and depth of subsurface damage (SSD). Effects of load, rotation speed, and slurry concentration during lapping on roughness, material removal rate, and SSD were investigated.

  17. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, Edward L.

    1985-01-01

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  18. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, E.L.

    1984-11-29

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  19. Predicting abrasive wear with coupled Lagrangian methods

    NASA Astrophysics Data System (ADS)

    Beck, Florian; Eberhard, Peter

    2015-05-01

    In this paper, a mesh-less approach for the simulation of a fluid with particle loading and the prediction of abrasive wear is presented. We are using the smoothed particle hydrodynamics (SPH) method for modeling the fluid and the discrete element method (DEM) for the solid particles, which represent the loading of the fluid. These Lagrangian methods are used to describe heavily sloshing fluids with their free surfaces as well as the interface between the fluid and the solid particles accurately. A Reynolds-averaged Navier-Stokes equations model is applied for handling turbulences. We are predicting abrasive wear on the boundary geometry with two different wear models taking cutting and deformation mechanisms into account. The boundary geometry is discretized with special DEM particles. In doing so, it is possible to use the same particle type for both the calculation of the boundary conditions for the SPH method as well as the DEM and for predicting the abrasive wear. After a brief introduction to the SPH method and the DEM, the handling of the boundary and the coupling of the fluid and the solid particles are discussed. Then, the applied wear models are presented and the simulation scenarios are described. The first numerical experiment is the simulation of a fluid with loading which is sloshing inside a tank. The second numerical experiment is the simulation of the impact of a free jet with loading to a simplified pelton bucket. We are especially investigating the wear patterns inside the tank and the bucket.

  20. Circular Signs of the Rock Abrasion Tool

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image was taken by Mars Exploration Rover Opportunity's front hazard-avoidance camera, providing a circular sign of the success of the rover's first grinding of a rock. The round, shallow hole seen in this image is on a rock dubbed 'McKittrick,' located in the 'El Capitan' area of the larger outcrop near Opportunity's landing site.

    Opportunity used its rock abrasion tool to grind off a patch of rock 45.5 millimeters (1.8 inches) in diameter during the 30th martian day, or sol, of its mission (Feb. 23, 2004). The grinding exposed fresh rock for close inspection by the rover's microscopic imager and two spectrometers located on its robotic arm. The Honeybee Robotics team, which designed and operates the rock abrasion tool, determined the depth of the cut at 'McKittrick' to be 4.4 millimeters (0.17 inches) deep.

    On sol 34 (Feb. 27, 2004), the rover is scheduled to grind into its second target on the 'El Capitan' area, a rock dubbed 'Guadalupe' in the upper middle part of this image. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

  1. Synthesis CNTs Particle Based Abrasive Media for Abrasive Flow Machining Process

    NASA Astrophysics Data System (ADS)

    Kumar, Sonu; Murtaza, Q.; Walia, R. S.; Dhull, S.; Tyagi, P. K.

    2016-02-01

    Abrasive flow machining (AFM) is a modem fine finishing process used for intricate and internal finishing of components or parts. It is based on flowing of viscoelastic abrasive media over the surface to be fine finished. The abrasive media is the important parameter in the AFM process because of its ability to accurately abrade the predefined area along it flow path. In this study, an attempt is made to develop a new abrasive, alumina with Carbon non tubes (CNTs) in viscoelastic medium. CNT s in house produced through chemical vapour deposition technique and characterize through TEM. Performance evaluation of the new abrasive media is carried out by increasing content of CNT s with fixed extrusion pressure, viscosity of media and media flow rate as process parameters and surface finish improvement and material removal as process responses in AFM setup. Significantly improvement has been observed in material removal and maximum improvement of 100% has been observed in the surface finish on the inner cylindrical surface of the cast iron work piece.

  2. Heat sealable, flame and abrasion resistant coated fabric. [clothing and containers for space exploration

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1981-01-01

    Flame retardant, abrasion resistant elastomeric compositions are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Coated fabrics employing such elastomeric compositions as coating film are flexible, lightweight, and air impermeable and can be made using heat or dielectric sealing procedures.

  3. Microstructure and Abrasive Wear Performance of Ni-Wc Composite Microwave Clad

    NASA Astrophysics Data System (ADS)

    Bansal, Amit; Zafar, Sunny; Sharma, Apurbba Kumar

    2015-10-01

    In the present work, Ni-WC powder was deposited on mild steel substrate to develop clads through microwave hybrid heating technique. The cladding trials were carried out in an industrial microwave applicator at 1.1 kW for 540 s. The Ni-WC composite clads were characterized for microstructure and abrasive wear performance through combination of x-ray diffraction, electron and optical microscopy, microhardness, and wear tests. Phase analysis of the Ni-WC clad indicated the presence of stable carbides such as WC, W2C, Ni2W4C, and Fe6W6C. The microstructure study of the clad layer revealed the presence of a uniformly distributed interlocked WC-based reinforcement embedded in the Ni-based matrix. The average Vicker's microhardness in the clad layer was observed to be 1028 ± 90 HV, which was approximately three times the microhardness of the substrate. Abrasive wear resistance of the microwave clads was superior to the MS substrate. Abrasion was the main wear mechanism in the Ni-WC clads and the substrate samples. However, the presence of WC-based reinforcement in the composite clads reduced microcutting, resulting in enhanced wear resistance.

  4. Abrasion and erosion testing of materials used in power production from coal

    SciTech Connect

    Tylczak, Joseph H.; Adler, Thomas A.; Rawers, James C.

    2003-09-01

    The Albany Research Center (ARC) has a long history of studying abrasive wear, related to mineral testing, handling, and processing. The center has also been instrumental in the design and development of wear test procedures and equipment. Research capabilities at ARC include Pin-on-Drum, Pin-on-Disk, and Dry Sand/Rubber Wheel abrasion tests, Jaw Crusher gouging test, Ball-on-Ball Impact test, and Jet erosion tests. Abrasive and erosive wear studies have been used to develop both new alloys and improved heat treatments of commercial alloys. As part of ARC’s newest iteration on wear testing to evaluate materials for use in new and existing pulverized coal combustion and gasifier power systems, the ARC has designed and constructed a new High Temperature Hostile Atmosphere Erosion Wear Test (HAET). This new piece of test apparatus is designed for erosive particle velocities of 10-40 m/sec and temperatures from room temperature (23°C) to 800+°C, with special control over the gas atmosphere. A variable speed whirling arm design is used to vary the impact energy of the gravity fed erosive particles. The specimens are mounted at the edge of a disk and allow a full range of impingement angles to be selected. An electric furnace heats the specimens in an enclosed retort to the selected temperature. Tests include both oxidizing conditions and reducing conditions. A range of gases, including CO, CO2, CH4, H2, H2S, HCl, N2, O2, and SO2 can be mixed and delivered to the retort. During the erosion testing a stream of abrasive powder is delivered in front of the specimens. This apparatus is designed to use low abrasive fluxes, which simulate real operating conditions in commercial power plants. Currently ~270 μm SiO2 particles are being used to simulate the abrasive impurities typically found in coal. Since operators are always striving for longer lifetimes and higher operating temperatures, this apparatus can help elucidate mechanisms of wastage and identify superior

  5. Polymer powder prepregging: Scoping study

    NASA Technical Reports Server (NTRS)

    Throne, James L.

    1988-01-01

    Early on, it was found that NEAT LARC-TPI thermoplastic polyimide powder behaved elastoplastically at pressures to 20 ksi and temperatures to 260 degrees celcius (below MP). At high resin assay, resin powder could be continuously cold-flowed around individual carbon fibers in a metal rolling mill. At low resin assay (2:1, C:TPI), fiber breakage was prohibitive. Thus, although processing of TPI below MP would be quite unique, it appears that the polymer must be melted and flowed to produce low resin assay prepreg. Fiber tow was spread to 75 mm using a venturi slot tunnel. This allowed intimate powder/fiber interaction. Two techniques were examined for getting room temperature powder onto the room temperature fiber surface. Electrostatic powder coating allows the charged powder to cling tenaciously to the fiber, even while heated with a hot air gun to above its melt temperature. A variant of the wet slurry coating process was also explored. The carbon fibers are first wetted with water. Then dry powder is sprinkled onto the wet tow and doctor-rolled between the fibers. The wet structure is then taken onto a heated roll, with hot air guns drying and sinter-melting the powder onto the fiber surfaces. In both cases SEM shows individual fibers coated with powder particles that have melted in place and flowed along the fiber surface via surface tension.

  6. Machining human dentin by abrasive water jet drilling.

    PubMed

    Kohorst, Philipp; Tegtmeyer, Sven; Biskup, Christian; Bach, Friedrich-Wilhelm; Stiesch, Meike

    2014-01-01

    The aim of this experimental in-vitro study was to investigate the machining of human dentin using an abrasive water jet and to evaluate the influence of different abrasives and water pressures on the removal rate. Seventy-two human teeth had been collected after extraction and randomly divided into six homogeneous groups (n=12). The teeth were processed in the area of root dentin with an industrial water jet device. Different abrasives (saccharose, sorbitol, xylitol) and water pressures (15 or 25 MPa) were used in each group. Dimensions of dentin removal were analysed using a stripe projection microscope and both drilling depth as well as volume of abrasion were recorded. Morphological analyses of the dentin cavities were performed using scanning electron microscopy (SEM). Both drilling depth and volume of abrasion were significantly influenced by the abrasive and the water pressure. Depending on these parameters, the drilling depth averaged between 142 and 378 μm; the volume of abrasion averaged between 0.07 and 0.15 mm3. Microscopic images revealed that all cavities are spherical and with clearly defined margins. Slight differences between the abrasives were found with respect to the microroughness of the surface of the cavities. The results indicate that abrasive water jet machining is a promising technique for processing human dentin. PMID:24642975

  7. The dollars and sense of selecting abrasion-resistant materials

    SciTech Connect

    Jackson, D.

    1988-05-01

    Sliding abrasion and impact damage affect mine and plant operating costs on a month-to-month, or, in some cases, day-to-day basis. Modern technology has given us the tools necessary to fight abrasion on every front - materials and techniques that are cost-effective, long-lasting, and easy to use. An inspection of abrasion-resistant materials and processes - metals; ceramics; sprayable and trowelable compounds; polyethylene; urethane; rubber; epoxy - may well provide information that could help improve your company's balance sheet. The following is a compilation of product releases, literature, and manuals offered by manufacturers of abrasion-resistant materials.

  8. The abrasion-wear resistance of arc sprayed stainless steel and composite stainless steel coatings

    SciTech Connect

    Dallaire, S.; Legoux, J.G.; Levert, H.

    1994-12-31

    Stainless steels are often used to palliate wear problems in various industries. Though they are not wear resistant, they have been used to a limited extent in applications involving both corrosive and abrasive/erosive environments. The protection of industrial components by arc sprayed stainless steel composite coatings could be considered very attractive provided these coatings offer a better wear protection than bulk stainless steel. The wear resistance of stainless steel and composite stainless steel-titanium boride coatings arc sprayed with air and argon was evaluated following the ASTM G-65 Abrasion Wear Test procedures. Wear volume loss measurements show that stainless steel coatings arc sprayed with air were slightly more resistant than bulk stainless steel while those sprayed with argon were slightly less resistant. The abrasion wear resistance of composite stainless steel-titanium diboride coatings is by two or four times beyond the wear resistance of bulk stainless steel depending upon the core wire constitution and the type of gas used for spraying. Microstructural analysis of coatings, microhardness measurements of sprayed lamellae and optical profilometry were used to characterize coatings and wear damages. Spraying with air instead of argon produced much more small particles. These particles, being removed from the metal sheath surface, are individually sprayed without diluting the concentration hard phases within cores. It results in coatings that contain large lamellae with hardnesses sufficient to withstand abrasion. By considering both the wire constitution and the spraying conditions, it was found possible to fabricate composite stainless steel coatings that show a 400% increase in wear resistance over bulk stainless steel.

  9. Pebble Jammed in Rock Abrasion Tool

    NASA Technical Reports Server (NTRS)

    2004-01-01

    After the rock abrasion tool on NASA's Mars Exploration Rover Opportunity stopped working on sol 199 (Aug. 15, 2004), rover operators used the panoramic camera to take this image the next day for help in diagnosing the problem. The tool was closer than the camera could focus on sharply, but the image does show a dark spot just left of center, which engineers have determined is likely to be a pebble jammed between the cutting-blade rotor and the wire-brush rotor. If that diagnosis is confirmed by further analysis, the tool will likely be commanded to turn the rotors in reverse to release the pebble.

  10. Mars Exploration Rovers' Rock Abrasion Tool

    NASA Astrophysics Data System (ADS)

    Gorevan, S.; Myrick, T.; Davis, K.; Ji, J.; Bartlett, P.; Mukherjee, S.; Arafat, T.

    2003-04-01

    Each of the twin 2003 Mars Exploration Rovers will be equipped with a Rock Abrasion Tool (RAT) designed and tested by Honeybee Robotics. The RAT is a robotic grinding tool and science instrument about the size of a soda can and weighing less than 690 grams that is carried by the robotic arm or Instrument Deployment Device (IDD) of the rover. The primary purpose of the RAT is to remove the dust and surface rind from Mars rock targets to reveal the underlying petrographic features. After the RAT is placed and preloaded against the target rock by the IDD, all operations of the RAT are performed autonomously. Using three small motors to drive the rotation, revolve and z-axis subassemblies the RAT removes a 45 mm diameter, 5 mm deep patch of rock. The RAT has a resin-bonded diamond abrasion wheel and two brushes to provide a clean observation surface for the three surface instruments - APXS, Microscopic Imager and Moessbauer Spectrometer. Detailed design and operation descriptions, as well as recent qualification and operational testing results will be presented.

  11. Container Prevents Oxidation Of Metal Powder

    NASA Technical Reports Server (NTRS)

    Woodford, William H.; Power, Christopher A.; Mckechnie, Timothy N.; Burns, David H.

    1992-01-01

    Sealed high-vacuum container holds metal powder required free of contamination by oxygen from point of manufacture to point of use at vacuum-plasma-spraying machine. Container protects powder from air during filling, storage, and loading of spraying machine. Eliminates unnecessary handling and transfer of powder from one container to another. Stainless-steel container sits on powder feeder of vacuum-plasma-spraying machine.

  12. Characterization of High-Temperature Abrasive Wear of Cold-Sprayed FeAl Intermetallic Compound Coating

    NASA Astrophysics Data System (ADS)

    Li, Chang-Jiu; Wang, Hong-Tao; Yang, Guan-Jun; Bao, Chong-Gao

    2011-01-01

    FeAl intermetallic compound coating was prepared by cold spraying using a mechanically alloyed Fe(Al) alloy powder followed by post-spray annealing at 950 °C. The high-temperature abrasive wear test was carried out for the FeAl coating at a temperature range from room temperature to 800 °C. The high-temperature abrasive wear of a heat-resistant stainless steel 2520 was performed for comparison. It was observed that the abrasive wear weight loss of FeAl coating was proportional to wear cycles in terms of sample revolutions at the tested temperatures. It was found that with the increase of the test temperature higher than 400 °C, the wear rate of cold-sprayed FeAl coating decreased with the increase of test temperature, while the wear rate of the heat-resistant steel increased significantly. The results indicate that the high-temperature abrasive wear resistance of the cold-sprayed FeAl intermetallic coating increased with the increase of the wear temperature in a temperature range from 400 to 800 °C. The wear resistance of cold-sprayed FeAl coating was higher than that of heat-resistant 2520 stainless steel under 800 °C by a factor of 3.

  13. Fabrication of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology

    NASA Astrophysics Data System (ADS)

    Luo, Sheng-Yih; Yu, Tsung-Han; Hu, Yuh-Chung

    2007-06-01

    A manufacturing process of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology is reported here. The thickness of JSR THB-151N resist coated on an aluminum alloy substrate for micro lithography can reach up to 110 µm. During the lithography, different geometrical photomasks were used to create specific design patterns of the resist mold on the substrate. Micro roots, made by electrolytic machining on the substrate with guidance of the resist mold, can improve the adhesion of micro nickel abrasive pellets electroplated on the substrate. During the composite electroforming, the desired hardness of the nickel matrix inside the micro diamond abrasive pellets can be obtained by the addition of leveling and stress reducing agents. At moderate blade agitation and ultrasonic oscillation, higher concentration and more uniform dispersion of diamond powders deposited in the nickel matrix can be achieved. With these optimal experiment conditions of this fabrication process, the production of micro nickel/diamond abrasive pellet array lapping tools is demonstrated.

  14. Microwave sintering of sol-gel derived abrasive grain

    DOEpatents

    Plovnick, Ross; Celikkaya, Ahmet; Blake, Rodger D.

    1997-01-01

    A method is provided for making microwave-sintered, free flowing alpha alumina-based ceramic abrasive grain, under conditions effective to couple microwaves with calcined alpha alumina-based abrasive gain precursor and sinter it at a temperature of at least about 1150.degree. C.

  15. Sand abrasion injury and biomass partitiioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  16. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Abrasive wheels and tools. 1926.303 Section 1926.303 Labor... (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Tools-Hand and Power § 1926.303 Abrasive wheels and tools. (a) Power. All grinding machines shall be supplied with sufficient power to maintain...

  17. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Abrasive device and accessories. 872.6010 Section 872.6010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and...

  18. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Abrasive device and accessories. 872.6010 Section 872.6010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and...

  19. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  20. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of the American National Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery....

  1. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of the American National Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery....

  2. Cotton seedling abrasion and recovery from wind blown sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares of crops are exposed to wind blown sand abrasion each year and in many instances the damage is thought to be severe enough to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton (Gossypium hirsutum L.) seedlings...

  3. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Abrasive wheel machinery. 1910.215 Section 1910.215 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery. (a... wheel in motion. (5) Excluded machinery. Natural sandstone wheels and metal, wooden, cloth, or...

  4. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of crops are exposed to wind blown sand abrasion injury each year and in many instances the damage is thought to be sufficiently severe to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton seedlings. Seedlings of ...

  5. Microfracture patterns of abrasive wear striations on teeth indicate directionality.

    PubMed

    Gordon, K R

    1984-03-01

    A method is described that will indicate the direction that an abrasive particle was traveling as it scored the surface of a brittle material. Light and scanning electron micrographs of glass, dentine, and enamel abraded by loose and, steel carbide, and diamond indicate that partial Hertzian fracture cones are formed at the margins of wear striations during abrasion. The bases of these fracture cones face in the direction of travel of the abrasive particle and, therefore, indicate directionality. Because this method is based only on the consistent geometry of fracturing of brittle materials, it is independent of the loading of the abrasive particle. The only other method available to determine directionality of striations is unreliable since it uses the width of striations, and, hence, is dependent upon a consistent loading regime of the abrasive particle. This new method has direct application for determining the direction of movement of the jaws during mastication in living or fossil animals. PMID:6731603

  6. Solidification Structure and Abrasion Resistance of High Chromium White Irons

    SciTech Connect

    Dogan, O.N.; Hawk, J.A.; Laird, George, II

    1997-06-01

    Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

  7. Solidification structure and abrasion resistance of high chromium white irons

    SciTech Connect

    Dogan, O.N.; Hawk, J.A.; Laird, G. II

    1997-06-01

    Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

  8. Microstructural effects in abrasive wear. Quarterly progress report, December 1980-1 June 1981. [Alloys for use in coal mining, handling, and gasification

    SciTech Connect

    Kosel, T.H.; Rao, M.C.; Shetty, H.R.; Fernandes, M.T.; Fiore, N.F.

    1981-10-29

    This report describes research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials, including high-Cr white irons and experimental Co-base and Ni-base powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling, and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion, and transfer applications. During this period, work was concentrated on analysis of results. The many detailed observations obtained in the work on scratch test simulations of abrasive wear mechanisms have been summarized in drafts of three papers. The first, A Study of Abrasive Wear Mechanisms Using Diamond and Alumina Scratch Tests, is included as an appendix to this report and is being submitted for publication. Revision of the other papers is in progress.

  9. Design of an impact abrasion testing machine

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Beeley, P. R.; Baker, A. J.

    1994-04-01

    By using a cam-flat follower-impact shaft with a crank-flat rotating anvil system, the machine to be described can create various impact abrasion conditions to simulate a large range of industrial situations encountered in this field. The main features of the machine are the long working life of the flat rotating anvil, which works in the same way as that of the disk in a pin-on-disk wear tester, and the accurate control of both the impact energy delivered to the specimen and the total sliding distance of the specimen on the anvil. Statistical analysis of test results on the machine with EN24 steel and cast high manganese steel shows that the uncertainty of the population mean is within +/- 4.7% of the sample mean under a 95% confidence level of student distribution, which indicates a very good accuracy of test.

  10. Mechanics, kinematics and geometry of pebble abrasion from binary collisions

    NASA Astrophysics Data System (ADS)

    Miller, K. L.; Jerolmack, D. J.

    2014-12-01

    As sediment is transported downstream as bedload, it collides with the bed causing sharp edges to chip and wear away, rounding the rock through the process of abrasion. Previous work has linked abrasion to downstream fining and rounding of grains, however, there has been little attempt to understand the underlying kinematics of abrasion. Furthermore, most studies neglect the fine particle produced during the abrasion process, as the initial grain gets smaller and rounder. In this research, we preform well-controlled laboratory experiments to determine the functional dependence between impact energy and mass lost from abrasion. We use a double-pendulum "Newton's Cradle" set-up to examine the abrasion between two grains and with a high-speed camera, we can quantify the impact energies during collision. Results from experiments verify that mass loss is proportional to kinetic energy. We define a material parameter that incorporates material density, Young's modulus, and tensile stress and show that this parameter is directly related to the proportionality between mass loss and energy. We identify an initial region of the mass loss curves in which abrasion is independent of energy and material properties; results suggest this region is determined by shape. We show that grain size distributions of daughter products are universal and independent of material; they follow a Weibull distribution, which is expected distribution from brittle fracture theory. Finally, scanning electron microscope (SEM) images show a thin damage zone near the surface, suggesting that collision energy is attenuated over some small skin depth. Overall, we find that pebble abrasion by collision can be characterized by two universal scaling relations - the mass loss versus energy curves and the size distribution of daughter products. Results will be useful for estimating expected abrasion rates in the field, and additionally demonstrate that low-energy collisions produce large quantities of sand

  11. The effects of abrasives on electrical submersible pumps

    SciTech Connect

    Wilson, B.L. )

    1990-06-01

    The electrical submersible pump (ESP) is a high-speed rotating device. Its operational life in oil wells can depend on the type and quantities of abrasives present in the produced fluid. This paper reports on a set of experiments performed in a specialized abrasive test loop. In the test, the size and quantity of abrasives were varied along with flow rate through the pump. This paper also examines recent literature on sand production and explores some of the practical problems in sand measurement.

  12. Method for forming an abrasive surface on a tool

    DOEpatents

    Seals, Roland D.; White, Rickey L.; Swindeman, Catherine J.; Kahl, W. Keith

    1999-01-01

    A method for fabricating a tool used in cutting, grinding and machining operations, is provided. The method is used to deposit a mixture comprising an abrasive material and a bonding material on a tool surface. The materials are propelled toward the receiving surface of the tool substrate using a thermal spray process. The thermal spray process melts the bonding material portion of the mixture, but not the abrasive material. Upon impacting the tool surface, the mixture or composition solidifies to form a hard abrasive tool coating.

  13. New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

    NASA Astrophysics Data System (ADS)

    Macias, F. J.; Dahl, F.; Bruland, A.

    2016-05-01

    The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and to evaluate the newly developed RIAT test method, a comprehensive laboratory testing programme including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.

  14. Effect of abrasive grit size on wear of manganese-zinc ferrite under three-body abrasion

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1987-01-01

    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and deformed layers produced in single-crystal Mn-Zn ferrites under three-body abrasion. The abrasion mechanism of Mn-Zn ferrite changes drastically with the size of abrasive grits. With 15-micron (1000-mesh) SiC grits, abrasion of Mn-Zn ferrite is due principally to brittle fracture; while with 4- and 2-micron (4000- and 6000-mesh) SiC grits, abrasion is due to plastic deformation and fracture. Both microcracking and plastic flow produce polycrystalline states on the wear surfaces of single-crystal Mn-Zn ferrites. Coefficient of wear, total thickness of the deformed layers, and surface roughness of the wear surfaces increase markedly with an increase in abrasive grit size. The total thicknesses of the deformed layers are 3 microns for the ferrite abraded by 15-micron SiC, 0.9 microns for the ferrite abraded by 4-micron SiC, and 0.8 microns for the ferrite abraded by 1-micron SiC.

  15. Improved wound healing in blue LED treated superficial abrasions

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Tatini, Francesca; Pini, Roberto; Bacci, Stefano; De Siena, Gaetano; Cicchi, Riccardo; Pavone, Francesco; Alfieri, Domenico

    2013-06-01

    A blue-LED photocoagulator device was designed in order to induce a selective photocoagulation effect in superficial bleeding. An in vivo study in rat back skin evidenced an improved healing process in the LED treated abrasions.

  16. Resistance of dentin coating materials against abrasion by toothbrush.

    PubMed

    Gando, Iori; Ariyoshi, Meu; Ikeda, Masaomi; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

    2013-01-01

    Thin-film coating of root dentin surface by all-in-one adhesives has been shown to be an effective option to prevent root surface caries. The purpose of this study was to investigate the wear resistance against toothbrush abrasion of two all-in-one coating materials; Shield Force (SF) and Hybrid Coat (HC). Bovine dentin surfaces were covered with one of the coating materials; SF or HC. After storage in water for 24 h, the testing surface was subjected to the toothbrush abrasion test up to 50,000 cycles either in water or toothpaste slurry. The remaining thickness of the coating material was measured using SEM. Toothpaste slurry significantly increased rate of tooth brush abrasion of the coating materials. While SF and HC wore at a similar pace under toothbrush abrasion, SF had a thicker coat and could protect dentin longer, up to 50,000 cycles. PMID:23370872

  17. Finished surface texture, abrasion resistance, and porosity of Aspa glass-ionomer cement.

    PubMed

    Smales, R; Joyce, K

    1978-11-01

    1. With the finishing agents tested Concise had a smoother surface texture than Aspa. 2. The smoothest surface was on Concise polymerized against a Mylar matrix strip. The smoothest surface for Aspa was obtained with a silicon carbide disk. 3. Aspa abraded about three times as rapidly by volume as Concise when tested by a two-body abrasion method. 4. Significantly more air bubbles were entrapped by hand mixing within Aspa than within Concise. 5. Controlled clinical studies of the glass-ionomer cements are needed before they can be fully evaluated as restorative materials. PMID:281506

  18. Dermoscopy and Onychomycosis: guided nail abrasion for mycological samples*

    PubMed Central

    Bet, Diego Leonardo; dos Reis, Ana Lucia; Chiacchio, Nilton Di; Belda Junior, Walter

    2015-01-01

    Mycological examination is still the cornerstone for the diagnosis of onychomycosis for many dermatologists, but sampling technique interferes on its sensitivity and specificity. Nail abrasion may be used to reach the most proximal part of the lesion and can be easily accomplished with an electric abrasor. We suggest nail plate dermoscopy to identify the best location for localized abrasion to obtain adequate samples for mycological examination. PMID:26734877

  19. Dermoscopy and Onychomycosis: guided nail abrasion for mycological samples.

    PubMed

    Bet, Diego Leonardo; Reis, Ana Lucia dos; Di Chiacchio, Nilton; Belda Junior, Walter

    2015-01-01

    Mycological examination is still the cornerstone for the diagnosis of onychomycosis for many dermatologists, but sampling technique interferes on its sensitivity and specificity. Nail abrasion may be used to reach the most proximal part of the lesion and can be easily accomplished with an electric abrasor. We suggest nail plate dermoscopy to identify the best location for localized abrasion to obtain adequate samples for mycological examination. PMID:26734877

  20. Dentifrice fluoride and abrasivity interplay on artificial caries lesions.

    PubMed

    Nassar, Hani M; Lippert, Frank; Eckert, George J; Hara, Anderson T

    2014-01-01

    Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions. PMID:24993884

  1. Computed tomography to quantify tooth abrasion

    NASA Astrophysics Data System (ADS)

    Kofmehl, Lukas; Schulz, Georg; Deyhle, Hans; Filippi, Andreas; Hotz, Gerhard; Berndt-Dagassan, Dorothea; Kramis, Simon; Beckmann, Felix; Müller, Bert

    2010-09-01

    Cone-beam computed tomography, also termed digital volume tomography, has become a standard technique in dentistry, allowing for fast 3D jaw imaging including denture at moderate spatial resolution. More detailed X-ray images of restricted volumes for post-mortem studies in dental anthropology are obtained by means of micro computed tomography. The present study evaluates the impact of the pipe smoking wear on teeth morphology comparing the abraded tooth with its contra-lateral counterpart. A set of 60 teeth, loose or anchored in the jaw, from 12 dentitions have been analyzed. After the two contra-lateral teeth were scanned, one dataset has been mirrored before the two datasets were registered using affine and rigid registration algorithms. Rigid registration provides three translational and three rotational parameters to maximize the overlap of two rigid bodies. For the affine registration, three scaling factors are incorporated. Within the present investigation, affine and rigid registrations yield comparable values. The restriction to the six parameters of the rigid registration is not a limitation. The differences in size and shape between the tooth and its contra-lateral counterpart generally exhibit only a few percent in the non-abraded volume, validating that the contralateral tooth is a reasonable approximation to quantify, for example, the volume loss as the result of long-term clay pipe smoking. Therefore, this approach allows quantifying the impact of the pipe abrasion on the internal tooth morphology including root canal, dentin, and enamel volumes.

  2. Method of protecting surfaces from abrasion and abrasion resistant articles of manufacture

    DOEpatents

    Hirschfeld, T.B.

    1988-06-09

    Surfaces of fabricated structures are protected from damage by impacting particulates by a coating of hard material formed as a mass of thin flexible filaments having root ends secured to the surface and free portions which can flex and overlap to form a resilient cushioning mat which resembles hair or fur. The filamentary coating covers the underlying surface with hard abrasion resistance material while also being compliant and capable of local accommodation to particle impacts. The coating can also function as thermal and/or acoustical insulation and has a friction reducing effect. 11 figs.

  3. Face powder poisoning

    MedlinePlus

    Face powder poisoning occurs when someone swallows or breathes in this substance. This article is for information ... The ingredients in face powder that can be harmful are: Baking soda Talcum powder Many other types of powder

  4. Atmospheric particulate emissions from dry abrasive blasting using coal slag.

    PubMed

    Kura, Bhaskar; Kambham, Kalpalatha; Sangameswaran, Sivaramakrishnan; Potana, Sandhya

    2006-08-01

    Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions. PMID:16933653

  5. Atmospheric particulate emissions from dry abrasive blasting using coal slag

    SciTech Connect

    Bhaskar Kura; Kalpalatha Kambham; Sivaramakrishnan Sangameswaran; Sandhya Potana

    2006-08-15

    Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions. 40 refs., 5 figs., 2 tabs.

  6. Analysis of Abrasive Blasting of DOP-26 Iridium Alloy

    SciTech Connect

    Ohriner, Evan Keith; Zhang, Wei; Ulrich, George B

    2012-01-01

    The effects of abrasive blasting on the surface geometry and microstructure of DOP-26 iridium alloy (Ir-0.3% W-0.006% Th 0.005% Al) have been investigated. Abrasive blasting has been used to control emissivity of components operating at elevated temperature. The effects of abrasive blasting conditions on surface morphology were investigated both experimentally and by numerical modeling. The simplified model, based on finite element analysis of a single angular particle impacting on Ir alloy disk, calculates the surface deformation and residual strain distribution. The experimental results and modeling results both indicate that the surface geometry is not sensitive to the abrasive blast process conditions of nozzle pressure and standoff distance considered in this study. On the other hand, the modeling results suggest that the angularity of the abrasive particle has an important role in determining surface geometry, which in turn, affects the emissivity. Abrasive blasting causes localized surface strains and localized recrystallization, but it does not affect grain size following extended exposure at elevated temperature. The dependence of emissivity of the DOP-26 alloy on mean surface slope follows a similar trend to that reported for pure iridium.

  7. Borosiliciding of Fe Ni alloys and evaluation of their resistance to abrasive wear

    NASA Astrophysics Data System (ADS)

    Sambogna, G.; Palombarini, G.; Carbucicchio, M.; Ciprian, R.

    2008-11-01

    X-ray diffraction analysis, Mössbauer measurements and metallographic observations were performed on borosilicide coatings grown at 850°C on Armco iron and the Fe64Ni36 binary alloy using a KBF4-activated powder mixture of B4C and Si3N4. The phase composition of the coatings was determined, a result allowing to show that the thermochemical treatment gives rise to iron boriding and iron siliciding reactions of different strength, depending on the treated material. The presence of Ni in the base metal allows iron-free nickel silicides to form as important components of the coating. The resistance of borosilicide coatings to abrasive wear is evaluated and discussed.

  8. Weavability of dry polymer powder towpreg

    NASA Technical Reports Server (NTRS)

    Hugh, Maylene K.; Marchello, Joseph M.; Maiden, Janice R.; Johnston, Norman J.

    1993-01-01

    Carbon fiber yarns (3k, 6k, 12k) were impregnated with LARC (tm) thermoplastic polyimide dry powder. Parameters for weaving these yarns were established. Eight-harness satin fabrics were successfully woven from each of the three classes of yarns and consolidated into test specimens to determine mechanical properties. It was observed that for optimum results warp yarns should have flexural rigidities between 10,000 and 100,000 mg-cm. Tow handling minimization, low tensioning, and tow bundle twisting were used to reduce fiber breakage, the separation of filaments, and tow-to-tow abrasion. No apparent effect of tow size or twist was observed on either tension or compression modulus. However, fiber damage and processing costs favor the use of 12k yarn bundles versus 3k or 6k yarn bundles in the weaving of powder-coated towpreg.

  9. A modified ASTM G-75 abrasion test helps select candidate alloys for service in a corrosive and abrasive slurry

    SciTech Connect

    Corbett, R.A.; Morrison, W.S.; Jenkins, C.F.; Westinghouse Savannah River Co., Aiken, SC )

    1989-01-01

    The design of a hazardous waste immobilization facility at the Savannah River Site (SRS) set material requirements for both abrasion resistance and corrosion resistance in process equipment. Standard ASTM slurry wear test G75 was modified to permit evaluation and comparison of abrasive resistance of candidate materials of construction in the laboratory. However, corrosion was found to contribute significantly to overall metal loss during the testing. Consequently, the abrasive slurry used for the testing was modified by adjusting its chemistry to include appropriate corrosive species. The Miller numbers obtained in the modified G75 Miller abrasion test are described. Pilot plant observations for Type 304L austenitic stainless steel were available. These data were used to generate a Morrison-Miller Ratio'' in order to determine anticipated field abrasion properties for other alloys. Hardness for many of the alloys fell in a narrow range about Rockwell B90, but performance varied significantly in response to slurry chemistry. This effect if synergistic may often be overlooked in the selection process, and it needs to be addressed. Some pilot plant testing of other alloys is essential to confirm the calculated abrasion rates and the approach of using the Morrison-Miller ratio. 6 refs., 3 figs., 5 tabs.

  10. Weldability of an abrasion-resistant steel

    SciTech Connect

    Adonyi, Y.; Domis, W.F.; Chen, C.C.

    1995-12-31

    The welding performance of a low-carbon-equivalent, abrasion-resistant steel newly developed for the mining industry was studied using a combination of simulative and actual weldability tests. The susceptibility to hydrogen-induced cracking in the weld-metal and heat-affected zones (HAZ), as well as the potential loss of strength and toughness in the HAZ, were evaluated. Simulative testing included the use of the Gleeble 1500 thermomechanical simulator to produce single and multiple-pass weld HAZ microstructures on CVN-size specimens. The effects of heat input, interpass temperature, and post-weld heat treatment (PWHT) on the HAZ microstructure and properties were determined. Additionally, a computer software was used to predict theoretical HAZ hardnesses and volume fraction of phases as a function of cooling rates. The actual welding tests included the Gapped Bead-on-Plate and the Y-groove tests to determine the weld-metal and HAZ susceptibility to hydrogen-induced cracking. Three heat inputs, two diffusible hydrogen and two weld-metal yield-strength levels were used for the actual welding stage. Good correlation was found between microstructure predictions, physical simulations, and actual weld testing results. The new steel was found to be highly weldable because of the low preheat required to avoid HAZ hydrogen induced cracking. All aspects of weld-metal and HAZ cracking behavior had to be addressed for a complete weldability characterization. It was also found that use of excessive heat inputs and PWHT should be avoided when welding this type of steels.

  11. Bound-abrasive grinding and polishing of surfaces of optical materials

    NASA Astrophysics Data System (ADS)

    Filatov, Yuriy D.; Filatov, Olexandr Y.; Monteil, Guy; Heisel, Uwe; Storchak, Michael

    2010-08-01

    Problems of improving efficiency and quality of diamond-abrasive finishing of optical materials by tools with bounded polishing powders, including diamond powder, by means of the improvement of the machining technology and application of new tools with functionally oriented designs and characteristics of working layer are considered. A model has been proposed of the slime particle formation and directional removal as well as of the generation of a high-quality surface in diamond-abrasive finishing of optical materials taking into account the peculiarities of the mass transfer in the contact zone and statistic character of the distribution of slime particles by size. The dependences of the particle number on the diffusion angle and coordinate of the contact have been derived in the studies of the dynamics of collision and diffusion of slime particles. The coordinate dependence of the flat surface roughness of glass K8 optics in fine diamond grinding has been described. Interaction and dispersion of deterioration particles in a contact zone of the tool and a processed sample in the course of polishing is described and the dispersion structure of deterioration particles of the tool on slime particles and on deterioration particles is explained oscillatory. It is shown, that differential dispersion section of deterioration particles on slime particles no less than on deterioration particles as much as possible at corners of dispersion close to 0 and 180° on the central sites of a contact zone. Coordinate dependence of full dispersion section of deterioration particles of the tool and dependence of microprofile height of the processed surface on circular zones radius are calculated. Conformity of experimental and theoretical microroughness profiles of a polished surface on a quartz sample is shown.

  12. Ceramic Powders

    NASA Technical Reports Server (NTRS)

    1984-01-01

    In developing its product line of specialty ceramic powders and related products for government and industrial customers, including companies in the oil, automotive, electronics and nuclear industries, Advanced Refractory Technologies sought technical assistance from NERAC, Inc. in specific areas of ceramic materials and silicon technology, and for assistance in identifying possible applications of these materials in government programs and in the automotive and electronics industry. NERAC conducted a computerized search of several data bases and provided extensive information in the subject areas requested. NERAC's assistance resulted in transfer of technologies that helped ART staff develop a unique method for manufacture of ceramic materials to precise customer specifications.

  13. Energetic powder

    DOEpatents

    Jorgensen, Betty S.; Danen, Wayne C.

    2003-12-23

    Fluoroalkylsilane-coated metal particles. The particles have a central metal core, a buffer layer surrounding the core, and a fluoroalkylsilane layer attached to the buffer layer. The particles may be prepared by combining a chemically reactive fluoroalkylsilane compound with an oxide coated metal particle having a hydroxylated surface. The resulting fluoroalkylsilane layer that coats the particles provides them with excellent resistance to aging. The particles can be blended with oxidant particles to form energetic powder that releases chemical energy when the buffer layer is physically disrupted so that the reductant metal core can react with the oxidant.

  14. Rock Abrasion Tool Exhibits the Deep Red Pigment of Mars

    NASA Technical Reports Server (NTRS)

    2006-01-01

    During recent soil-brushing experiments, the rock abrasion tool on NASA's Mars Exploration Rover Spirit became covered with dust, as shown here. An abundance of iron oxide minerals in the dust gave the device a reddish-brown veneer. Investigators were using the rock abrasion tool to uncover successive layers of soil in an attempt to reveal near-surface stratigraphy. Afterward, remnant dirt clods were visible on both the bit and the brush of the tool. Designers of the rock abrasion tool at Honeybee Robotics and engineers at the Jet Propulsion Laboratory developed a plan to run the brush on the rock abrasion tool in reverse to dislodge the dirt and return the tool to normal operation. Subsequent communications with the rover revealed that the procedure is working and the rock abrasion tool remains healthy.

    Spirit acquired this approximately true-color image with the panoramic camera on the rover's 893rd sol, or Martian day (July 8, 2006). The image combines exposures taken through three of the camera's filters, centered on wavelengths of 750 nanometers, 530 nanometers, and 430 nanometers.

  15. Abrasion of Candidate Spacesuit Fabrics by Simulated Lunar Dust

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Meador, Mary Ann; Rogers, Kerry J.; Sheehy, Brennan H.

    2009-01-01

    A protocol has been developed that produced the type of lunar soil abrasion damage observed on Apollo spacesuits. This protocol was then applied to four materials (Kevlar (DuPont), Vectran (Kuraray Co., Ltd.), Orthofabric, and Tyvek (DuPont)) that are candidates for advanced spacesuits. Three of the four new candidate fabrics (all but Vectran) were effective at keeping the dust from penetrating to layers beneath. In the cases of Kevlar and Orthofabric this was accomplished by the addition of a silicone layer. In the case of Tyvek, the paper structure was dense enough to block dust transport. The least abrasive damage was suffered by the Tyvek. This was thought to be due in large part to its non-woven paper structure. The woven structures were all abraded where the top of the weave was struck by the abrasive. Of these, the Orthofabric suffered the least wear, with both Vectran and Kevlar suffering considerably more extensive filament breakage.

  16. Review of scratch test studies of abrasion mechanisms

    SciTech Connect

    Kosel, T.H.

    1986-01-01

    The use of scratch tests to simulate the material removal mechanisms which occur during abrasion is reviewed. Although useful studies of the effect of the rake angle on material removal have been carried out using diamond tools, closer simulation of the mechanisms of material removal can be obtained using actual irregular individual abrasive particles as scratch tools. Previous studies are reviewed in which scratch tests have been performed with both conventional scratch test instruments and a specially designed system used for )ital in situ) scratch tests in the scanning electron microscope (SEM). Multiple-pass scratch tests over the same scratch path have been shown to create surface features and wear debris particles which are very similar to those produced by low-stress abrasion. Alumina (Al/sub 2/O/sub 3/) particles have been shown to produce continuous micromachining chips from the hard, brittle carbide phase of Stellite alloys, establishing direct cutting as the important mechanism of material removal for this type of abrasive. An )ital in situ) study of material removal from white cast irons by quartz particles has provided conclusive evidence that carbide removal does not occur by direct cutting but rather always involves microfracture. Previously unpublished work which has compared scratch tests with crushed quartz and alumina particles is included. Also described is a new scratch test system which controls the depth of cut rather than the scratch load in order to simulate high-stress abrasion, in which abrasive particles are constrained to a fixed depth of cut. Preliminary new results show substantially different carbide fracture behavior under fixed-depth conditions. 8 figs., 20 refs.

  17. Aeolian Abrasion, a Dominant Erosion Agent in the Martian Environment

    NASA Astrophysics Data System (ADS)

    Bridges, N.; Cooper, G.; Eddlemon, E.; Greeley, R.; Laity, J.; Phoreman, J.; Razdan, A.; van Note, S.; White, B.; Wilson, G.

    2004-12-01

    Aeolian abrasion is one of the predominant erosion mechanisms on Mars today. Martian ventifacts record the climate under which the rocks were modified (wind direction, wind speeds and particle flux) and therefore tie into the overall climatic regime of the planet. By better understanding the rates at which rocks abrade and the features diagnostic of specific climatic conditions, we can gain insight into past climates. Herein we report on numerical models, wind tunnel experiments, and field work to determine 1) Particle and kinetic fluxes on Earth and Mars, 2) the degree to which these parameters control abrasion, and 3) how, in detail, rocks of various shapes and compositions erode over time. Kinetic energy generally increases with height, whereas flux decreases, and impact angles, which affect energy transfer, and rebound effects are functions of the rock facet angle. This results in a non-linear relationship between abrasion potential and height that is a function of wind speed, planetary environment, and target geometry. We have computed the first three of these parameters numerically using a numerical saltation code, combined with published flux calculations These results have been compared to wind tunnel tests of flux vs. height, abrasion of erodible targets, and high speed video analysis under terrestrial and Martian pressures. We are also using high resolution laser scanning to characterize textures, shapes, and weathering changes for terrestrial and Martian rocks at the 100s of microns scale. We find that facet angle, texture, and rock heterogeneity are of critical importance in determining the rate and style of abrasion. Field and theoretical results demonstrate that high speed winds, not the integrated flux of lower speeds, and sand, not dust, produce most rock abrasion. On Mars, this requires sustained winds above 20-25 m/s at the near surface, a challenge in the current environment.

  18. Dental abrasion pattern in a selected group of Malaysians.

    PubMed

    Yaacob, H B; Park, A W

    1990-09-01

    Among 350 inhabitants of two villages, 31 (8.9%) cleaned their teeth using table salt and charcoal applied to their forefinger or a Melastoma brush. As a result, all had distinct forms of abrasion cavity on the labial surfaces of their teeth. All of the above three agents are highly abrasive and injurious to both the hard and soft oral tissues. This dying practice is only popular among a very small number of persons in the older age group, and should be discouraged. PMID:2230960

  19. Field evidence of two-phase abrasion process

    NASA Astrophysics Data System (ADS)

    Miller, K. L.; Szabo, T.; Jerolmack, D. J.; Domokos, G.

    2013-12-01

    The rounded shape of river rocks is clear evidence that abrasion due to bed load transport is a significant agent for mass loss. Its contribution to downstream fining, however, is typically assumed to be negligible - as diminution trends may be explained solely by size-selective transport. A recent theory has predicted that pebble abrasion occurs in two well separated phases: in Phase 1, an intially-polyhedral pebble rounds to the shape of an inscribed ellipsoid without any change in axis dimensions; in Phase II, axis dimensions are slowly reduced. Importantly, Phase I abrasion means that an initially-blocky pebble may lose up to half its mass without any apparent change in 'size', which is only measured as the length of a single pebble axis by most field researchers. We hypothesize that field studies have significantly underestimated the importance of abrasion because they do not quantify pebble shape, and we set out to demonstrate that two-phase abrasion occurs in a natural stream. Our study examines downstream trends in pebble size and shape along a 10-km stretch of the Rio Mameyes within the Luquillo Critical Zone observatory, where volcaniclastic cobbles and boulders are transported by bed load at slopes up to 10%. The upper reaches of the stream consist of alluviated bedrock valleys that preclude sediment storage and thus minimize size-selective transport, which allows us to isolate the effects of abrasion. The lower 5 km is an alluvial river in which size-selective transport becomes operative. We quantified the shape and size of thousands of pebbles along the profile using hand and image-based techniques. The data provide the first field validation of two-phase abrasion; in the bedrock reaches, pebbles clearly evolve toward ellipsoids without any significant change in axis dimensions (rounding), while in the lower reaches pebbles slowly reduce their axis dimensions with little or no change in roundness. Results also show that shape metrics determined from

  20. Powder treatment process

    DOEpatents

    Weyand, J.D.

    1988-02-09

    Disclosed are: (1) a process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder. 2 figs.

  1. Powder treatment process

    DOEpatents

    Weyand, John D.

    1988-01-01

    (1) A process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder.

  2. Bound-abrasive grinding and polishing of surfaces of optical materials

    NASA Astrophysics Data System (ADS)

    Filatov, Yuriy D.; Filatov, Olexandr Yu.; Monteil, Guy; Heisel, Uwe; Storchak, Michael

    2011-06-01

    Problems of efficiency and quality improvement of diamond-abrasive finishing of optical materials by tools with bounded polishing powders, including diamond powder, are considered. The dependences of the particle number on the diffusion angle and coordinate of the contact have been derived in the studies of the dynamics of collision and diffusion of slime particles. The coordinate dependence of the flat surface roughness of glass K8 optics in fine diamond grinding has been described. Interaction and dispersion of deterioration particles in a contact zone of the tool and the processed sample in the course of polishing is described and the dispersion structure of deterioration particles of the tool on slime particles and on deterioration particles is explained oscillatory. It is shown a that differential dispersion section of deterioration particles on slime particles is not less than on deterioration particles and is maximum at corners of dispersion close to 0° and 180° on the central sites of a contact zone. Coordinate dependence of the full dispersion section of deterioration particles of the tool and dependence of microprofile height of the processed surface on circular zones radius are calculated.

  3. Exposure to crystalline silica in abrasive blasting operations where silica and non-silica abrasives are used.

    PubMed

    Radnoff, Diane L; Kutz, Michelle K

    2014-01-01

    Exposure to respirable crystalline silica is a hazard common to many industries in Alberta but particularly so in abrasive blasting. Alberta occupational health and safety legislation requires the consideration of silica substitutes when conducting abrasive blasting, where reasonably practicable. In this study, exposure to crystalline silica during abrasive blasting was evaluated when both silica and non-silica products were used. The crystalline silica content of non-silica abrasives was also measured. The facilities evaluated were preparing metal products for the application of coatings, so the substrate should not have had a significant contribution to worker exposure to crystalline silica. The occupational sampling results indicate that two-thirds of the workers assessed were potentially over-exposed to respirable crystalline silica. About one-third of the measurements over the exposure limit were at the work sites using silica substitutes at the time of the assessment. The use of the silica substitute, by itself, did not appear to have a large effect on the mean airborne exposure levels. There are a number of factors that may contribute to over-exposures, including the isolation of the blasting area, housekeeping, and inappropriate use of respiratory protective equipment. However, the non-silica abrasives themselves also contain silica. Bulk analysis results for non-silica abrasives commercially available in Alberta indicate that many contain crystalline silica above the legislated disclosure limit of 0.1% weight of silica per weight of product (w/w) and this information may not be accurately disclosed on the material safety data sheet for the product. The employer may still have to evaluate the potential for exposure to crystalline silica at their work site, even when silica substitutes are used. Limited tests on recycled non-silica abrasive indicated that the silica content had increased. Further study is required to evaluate the impact of product recycling

  4. Abrasion cross sections for Ne-20 projectiles at 2.1 GeV/nucleon

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.

    1983-01-01

    Utilizing eikonal scattering theory, an optical model potential approximation to the exact nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision formalism to predict abrasion cross sections for relativistic Ne-20 projectile nuclei. Excellent agreement with recent experimental abrasion results is obtained. The sensitivity of the abrasion predictions to Pauli exclusion principle correlation effects and to the assumed shape of the nuclear single-particle density distribution is also demonstrated.

  5. Development of a thermal reclamation system for spent blasting abrasive

    SciTech Connect

    Bryan, B.B.; Mensinger, M.C.; Rehmat, A.G.

    1991-01-01

    Abrasive blasting is the most economical method for paint removal from large surface areas such as the hulls and tanks of oceangoing vessels. Tens of thousands of tons of spent abrasive are generated annually by blasting operations in private and US Navy shipyards. Some of this material is classified as hazardous waste, and nearly all of it is currently being either stockpiled or disposed in landfills. The rapid decline in available landfill space and corresponding rise in landfill tipping fees pose a severe problem for shipyard operators throughout the US. This paper discusses the results of a research and development program initiated by the Institute of Gas Technology and supported by the US Navy to develop and test a fluidized-bed thermal reclamation system for spent abrasive waste minimization. Bench- and pilot-scale reclaimer tests and reclaimed abrasive performance tests are described along with the current status of a program to build and test a 5-ton/hour prototype reclaimer at a US Navy shipyard.

  6. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... wheel in motion. (5) Excluded machinery. Natural sandstone wheels and metal, wooden, cloth, or paper... apply to natural sandstone wheels or metal, wooden, cloth, or paper discs, having a layer of abrasive on... and Type 27A cutting-off wheels. (g) Certain internal wheels. (h) Type 4 tapered wheels. (i)...

  7. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... wheel in motion. (5) Excluded machinery. Natural sandstone wheels and metal, wooden, cloth, or paper... apply to natural sandstone wheels or metal, wooden, cloth, or paper discs, having a layer of abrasive on... and Type 27A cutting-off wheels. (g) Certain internal wheels. (h) Type 4 tapered wheels. (i)...

  8. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... spindle speed at safe levels under all conditions of normal operation. (b) Guarding. (1) Grinding machines.... (1) Floor stand and bench mounted abrasive wheels, used for external grinding, shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and...

  9. A nonmineralized approach to abrasion-resistant biomaterials

    PubMed Central

    Pontin, Michael G.; Moses, Dana N.; Waite, J. Herbert; Zok, Frank W.

    2007-01-01

    The tooth-like mouthparts of some animals consist of biomacromolecular scaffolds with few mineral components, making them intriguing paradigms of biostructural materials. In this study, the abrasion resistance of the jaws of one such animal, the bloodworm Glycera dibranchiata, has been evaluated by nanoindentation, nanoscratching, and wear testing. The hardest, stiffest, and most abrasion-resistant materials are found within a thin (<3 μm) surface layer near the jaw tip and a thicker (10–20 μm) subsurface layer, both rich in unmineralized Cu. These results are consistent with the supposition that Cu ions are involved in the formation of intermolecular coordination complexes between proteins, creating a highly cross-linked molecular network. The intervening layer contains aligned atacamite [Cu2(OH)3Cl] fibers and exhibits hardness and stiffness (transverse to the alignment direction) that are only slightly higher than those of the bulk material but lower than those of the two Cu-rich layers. Furthermore, the atacamite-containing layer is the least abrasion-resistant, by a factor of ≈3, even relative to the bulk material. These observations are broadly consistent with the behavior of engineering polymer composites with hard fiber or particulate reinforcements. The alignment of fibers parallel to the jaw surface, and the fiber proximity to the surface, are both suggestive of a natural adaptation to enhance bending stiffness and strength rather than to endow the surface regions with enhanced abrasion resistance. PMID:17702868

  10. Innovative decontamination technology by abrasion in vibratory vessels

    SciTech Connect

    Fabbri, Silvio; Ilarri, Sergio

    2007-07-01

    Available in abstract form only. Full text of publication follows: The possibility of using conventional vibratory vessel technology as a decontamination technique is the motivation for the development of this project. The objective is to explore the feasibility of applying the vibratory vessel technology for decontamination of radioactively-contaminated materials such as pipes and metal structures. The research and development of this technology was granted by the U.S. Department of Energy (DOE). Abrasion processes in vibratory vessels are widely used in the manufacture of metals, ceramics, and plastics. Samples to be treated, solid abrasive media and liquid media are set up into a vessel. Erosion results from the repeated impact of the abrasive particles on the surface of the body being treated. A liquid media, generally detergents or surfactants aid the abrasive action. The amount of material removed increases with the time of treatment. The design and construction of the machine were provided by Vibro, Argentina private company. Tests with radioactively-contaminated aluminum tubes and a stainless steel bar, were performed at laboratory level. Tests showed that it is possible to clean both the external and the internal surface of contaminated tubes. Results show a decontamination factor around 10 after the first 30 minutes of the cleaning time. (authors)

  11. Surface carbonization of titanium for abrasion-resistant implant materials.

    PubMed

    Zhu, Yuhe; Watari, Fumio

    2007-03-01

    Carbide layer was formed on the surface of Ti by heating in hydrocarbon atmosphere (benzene C6H6) at 1000-1400 degrees C using a high frequency induction heating method. Physical and mechanical properties of carbide-coated Ti were investigated to examine its potential as an abrasion-resistant implant material. Scanning electron microscopy (SEM) showed that the surface of Ti was covered with fine grains of 1-4 microm diameter, depending on heating conditions. In addition, carbide layer of about 1-25 microm thickness was observed on the cross-section of specimens by SEM and energy dispersive spectroscopy. Vickers hardness of surface carbide was found to be more than 2000. Further, Martens scratch test and ultrasonic scaler abrasion test showed that the indentation depth and width of carbide-coated Ti were much smaller than pure Ti, thereby confirming its high abrasion resistance. These results showed that for Ti implant materials that require high abrasion resistance, such as the abutment for dental implants, surface carbide coatings would be an effective means to improve their wear properties. PMID:17621941

  12. Abrasive blasting agents: designing studies to evaluate relative risk.

    PubMed

    Hubbs, Ann; Greskevitch, Mark; Kuempel, Eileen; Suarez, Fernando; Toraason, Mark

    Workers exposed to respirable crystalline silica used in abrasive blasting are at increased risk of developing a debilitating and often fatal fibrotic lung disease called silicosis. The National Institute for Occupational Safety and Health (NIOSH) recommends that silica sand be prohibited as abrasive blasting material and that less hazardous materials be used in blasting operations. However, data are needed on the relative risks associated with exposure to abrasive blasting materials other than silica. NIOSH has completed acute studies in rats (Hubbs et al., 2001; Porter et al., 2002). To provide dose-response data applicable to making recommendation for occupational exposure limits, NIOSH has collaborated with the National Toxicology Program (NTP) to design longer term studies with silica substitutes. For risk assessment purposes, selected doses will include concentrations that are relevant to human exposures. Rat lung burdens achieved should be comparable to those estimated in humans with working lifetime exposures, even if this results in "overloading" doses in rats. To quantify both dose and response, retained particle burdens in the lungs and lung-associated lymph nodes will be measured, as well as biochemical and pathological indices of pulmonary response. This design will facilitate assessment of the pulmonary fibrogenic potential of inhaled abrasive blasting agents at occupationally relevant concentrations. PMID:16020188

  13. Preparation of metal diboride powders

    DOEpatents

    Brynestad, J.; Bamberger, C.E.

    Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group of consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

  14. Preparation of titanium diboride powder

    DOEpatents

    Brynestad, Jorulf; Bamberger, Carlos E.

    1985-01-01

    Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

  15. Solid Lubrication Fundamentals and Applications. Chapter 5; Abrasion: Plowing and Cutting

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2001-01-01

    Chapter 5 discusses abrasion, a common wear phenomenon of great economic importance. It has been estimated that 50% of the wear encountered in industry is due to abrasion. Also, it is the mechanism involved in the finishing of many surfaces. Experiments are described to help in understanding the complex abrasion process and in predicting friction and wear behavior in plowing and/or cutting. These experimental modelings and measurements used a single spherical pin (asperity) and a single wedge pin (asperity). Other two-body and three-body abrasion studies used hard abrasive particles.

  16. Tribocharging behaviour of automotive powder coatings

    NASA Astrophysics Data System (ADS)

    Thomas, Aline; Saleh, Khashayar; Guigon, Pierre; Czechowski, Claire

    2008-12-01

    The aim of this work was to build a device allowing the measurement of tribocharging during the fluidization and pneumatic transport of automotive powder coatings. The experimental setup included a fluidization unit, a transport pipe and two 'Faraday cups' allowing continuous monitoring of particle charge. Two batches of industrial automotive powder primers, as well as several other types of powders were tested: alumina, silica... The experimental variables were the length of the conveying pipe and the air flow rate. The results showed that the net amount of acquired tribocharge increases with the length of conveying pipe. The experimental device and procedure allowed to well classify tested powders according to their rate of tribocharging and their maximum charge. More specially, this study pointed out a net difference between electrostatic properties of two powder primers, which behave very differently in the industrial application unit.

  17. Comparative study of talc poudrage versus pleural abrasion for the treatment of primary spontaneous pneumothorax†

    PubMed Central

    Moreno-Merino, Sergio; Congregado, Miguel; Gallardo, Gregorio; Jimenez-Merchan, Rafael; Trivino, Ana; Cozar, Fernando; Lopez-Porras, Marta; Loscertales, Jesus

    2012-01-01

    Primary spontaneous pneumothorax is a pathology mainly affecting healthy young patients. Clinical guidelines do not specify the type of pleurodesis that should be conducted, due to the lack of comparative studies on the different techniques. The aim of this study was to compare talc poudrage and pleural abrasion in the treatment of spontaneous pneumothorax. A retrospective comparative study was performed, including 787 patients with primary spontaneous pneumothorax. The 787 patients were classified into two groups: Group A (pleural abrasion) n = 399 and Group B (talc pleurodesis) n = 388. The variables studied were recurrence, surgical time, morbidity and in-hospital length of stay. Statistical analysis was done by an unpaired t-test and Fisher's exact test (SSPS 18.0). Statistically significant differences were observed in the variables: surgical time (A: 46 ± 12.3; B: 37 ± 11.8 min; P < 0.001); length of stay (A: 4.7 ± 2.5; B: 4.3 ± 1.8 days; P = 0.01); apical air camera (A: 25; B: 4; P < 0.001); pleural effusion (A: 6; B: 0; P = 0.05). Talc poudrage shows shorter surgical times and length of stay, and lower re-intervention rates. Morbidity is lower in patients with talc poudrage. Statistically significant differences were not observed in recurrence, persistent air leaks, atelectasis and haemothorax. PMID:22514256

  18. Wheel Abrasion Experiment Metals Selection for Mars Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Fatemi, Navid S.; Wilt, David M.; Ferguson, Dale C.; Hoffman, Richard; Hill, Maria M.; Kaloyeros, Alain E.

    1996-01-01

    A series of metals was examined for suitability for the Wheel Abrasion Experiment, one of ten microrover experiments of the Mars Pathfinder Mission. The seven candidate metals were: Ag, Al, Au, Cu, Ni, Pt, and W. Thin films of candidate metals from 0.1 to 1.0 micrometer thick were deposited on black anodized aluminum coupons by e-beam and resistive evaporation and chemical vapor deposition. Optical, corrosion, abrasion, and adhesion criteria were used to select Al, Ni, and Pt. A description is given of the deposition and testing of thin films, followed by a presentation of experimental data and a brief discussion of follow-on testing and flight qualification.

  19. Abrasion Testing of Critical Components of Hydrokinetic Devices

    SciTech Connect

    Worthington, Monty; Ali, Muhammad; Ravens, Tom

    2013-12-06

    The objective of the Abrasion Testing of Critical Components of Hydrokinetic Devices (Project) was to test critical components of hydrokinetic devices in waters with high levels of suspended sediment – information that is widely applicable to the hydrokinetic industry. Tidal and river sites in Alaska typically have high suspended sediment concentrations. High suspended sediment also occurs in major rivers and estuaries throughout the world and throughout high latitude locations where glacial inputs introduce silt into water bodies. In assessing the vulnerability of technology components to sediment induced abrasion, one of the greatest concerns is the impact that the sediment may have on device components such as bearings and seals, failures of which could lead to both efficiency loss and catastrophic system failures.

  20. Nanometric Finishing on Biomedical Implants by Abrasive Flow Finishing

    NASA Astrophysics Data System (ADS)

    Subramanian, Kavithaa Thirumalai; Balashanmugam, Natchimuthu; Shashi Kumar, Panaghra Veeraiah

    2016-01-01

    Abrasive flow finishing (AFF) is a non-conventional finishing technique that offers better accuracy, efficiency, consistency, economy in finishing of complex/difficult to machine materials/components and provides the possibility of effective automation as aspired by the manufacturing sector. The present study describes the finishing of a hip joint made of ASTM grade Co-Cr alloy by Abrasive Flow Machining (AFM) process. The major input parameters of the AFF process were optimized for achieving nanometric finishing of the component. The roughness average (Ra) values were recorded during experimentation using surface roughness tester and the results are discussed in detail. The surface finished hip joints were characterized using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and residual stress analysis using X-Ray Diffraction (XRD). The discussion lays emphasis on the significance, efficacy and versatile nature of the AFF process in finishing of bio-medical implants.

  1. Microstructure and abrasive wear in silicon nitride ceramics

    SciTech Connect

    Dogan, Cynthia P.; Hawk, Jeffrey A.

    2001-10-01

    It is well known that abrasive wear resistance is not strictly a materials property, but also depends upon the specific conditions of the wear environment. Nonetheless, characteristics of the ceramic microstructure do influence its hardness and fracture toughness and must, therefore, play an active role in determining howa ceramic will respond to the specific stress states imposed upon it by the wear environment. In this study, the ways in which composition and microstructure influence the abrasive wear behavior of six commercially-produced silicon nitride based ceramics are examined. Results indicate that microstructural parameters, such as matrix grain size and orientation, porosity, and grain boundary microstructure, and thermal expansion mismatch stresses created as the result of second phase formation, influence the wear rate through their effect on wear sheet formation and subsurface fracture. It is also noted that the potential impact of these variables on the wear rate may not be reflected in conventional fracture toughness measurements.

  2. A physically-based abrasive wear model for composite materials

    SciTech Connect

    Lee, Gun Y.; Dharan, C.K.H.; Ritchie, Robert O.

    2001-05-01

    A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of the reinforcement is estimated by modeling the three primary wear mechanisms, specifically plowing, interfacial cracking and particle removal. Critical variables describing the role of the reinforcement, such as its relative size and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy matrix composite material.

  3. Self inflicted corneal abrasions due to delusional parasitosis

    PubMed Central

    Meraj, Adeel; Din, Amad U; Larsen, Lynn; Liskow, Barry I

    2011-01-01

    The authors report a case of self inflicted bilateral corneal abrasions and skin damage due to ophthalmic and cutaneous delusional parasitosis. A male in his 50s presented with a 10 year history of believing that parasites were colonizing his skin and biting into his skin and eyes. The patient had received extensive medical evaluations that found no evidence that symptoms were due to a medical cause. He was persistent in his belief and had induced bilateral corneal abrasions and skin damage by using heat lamps and hair dryers in an attempt to disinfect his body. The patient was treated with olanzapine along with treatment for his skin and eyes. His delusional belief system persisted but no further damage to his eyes and skin was noted on initial follow-up. PMID:22689836

  4. Assessment of Abrasive Wear of Nanostructured WC-Co and Fe-Based Coatings Applied by HP-HVOF, Flame, and Wire Arc Spray

    NASA Astrophysics Data System (ADS)

    Lima, C. R. C.; Libardi, R.; Camargo, F.; Fals, H. C.; Ferraresi, V. A.

    2014-10-01

    Thermal spray processes have been widely used to minimize losses caused by wear mechanisms. Sprayed deposits using conventional wire and powder materials have been long solving tribological problems in engineering equipment. More recently, the option for new different technologies and consumables like nanostructured powder materials and nanocomposite cored wires have expanded the possibilities for technical solutions. Cored wire technology allows the use of compositions that cannot be drawn into wire form like carbides in metallic matrix and high-temperature materials, thus, intensifying the use of spraying processes with low operating cost to demanding wear and corrosion applications. The objective of this work was to study the mechanical characteristics and wear performance of coatings obtained by Flame, Wire Arc, and HVOF spraying using selected nanostructured WC10Co4Cr, WC12Co, and Fe-based 140 MXC powder and wire materials. Abrasive wear performance of the coatings was determinate following the ASTM G-65 standard. Based on the results, a higher abrasive wear resistance was found for the HVOF-sprayed WC10Co4Cr nanostructured coating.

  5. Wear and abrasion resistance selection maps of biological materials.

    PubMed

    Amini, Shahrouz; Miserez, Ali

    2013-08-01

    The mechanical design of biological materials has generated widespread interest in recent years, providing many insights into their intriguing structure-property relationships. A critical characteristic of load-bearing materials, which is central to the survival of many species, is their wear and abrasion tolerance. In order to be fully functional, protective armors, dentitious structures and dynamic appendages must be able to tolerate repetitive contact loads without significant loss of materials or internal damage. However, very little is known about this tribological performance. Using a contact mechanics framework, we have constructed materials selection charts that provide general predictions about the wear performance of biological materials as a function of their fundamental mechanical properties. One key assumption in constructing these selection charts is that abrasion tolerance is governed by the first irreversible damage at the contact point. The maps were generated using comprehensive data from the literature and encompass a wide range of materials, from heavily mineralized to fully organic materials. Our analysis shows that the tolerance of biological materials against abrasion depends on contact geometry, which is ultimately correlated to environmental and selective pressures. Comparisons with experimental data from nanoindentation experiments are also drawn in order to verify our predictions. With the increasing amount of data available for biological materials also comes the challenge of selecting relevant model systems for bioinspired materials engineering. We suggest that these maps will be able to guide this selection by providing an overview of biological materials that are predicted to exhibit the best abrasion tolerance, which is of fundamental interest for a wide range of applications, for instance in restorative implants and protective devices. PMID:23643608

  6. Raising the resistance of mainline pump parts to hydraulic abrasion

    SciTech Connect

    Belousov, V.Ya.; Borisenko, V.V.; Zhuravlev, Yu.V.

    1988-01-01

    The authors investigate the diffusion coating of mainline petroleum pump surfaces with boron carbides and the subsequent hardness and abrasion resistance of the working surfaces based on the temperature of the treatment and the depth and concentration of the coating. Industrial testing on an NM 2500 x 230 centrifugal pump demonstrated an increase in service life by a factor of 2 to 2.5. The process has been put into production at an annual savings per pump of 4000 rubles.

  7. Abrasion of Candidate Spacesuit Fabrics by Simulated Lunar Dust

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Meador, Mary Ann; Rogers, Kerry J.; Sheehy, Brennan H.

    2009-01-01

    A protocol has been developed that produced the type of lunar soil abrasion damage observed on Apollo spacesuits. This protocol was then applied to four materials (Kevlar(Registered TradeMark), Vectran(Registered TradeMark), Orthofabric, and Tyvek(Registered TradeMark)) that are candidates for advanced spacesuits. Three of the four new candidate fabrics (all but Vectran(Registered TradeMark)) were effective at keeping the dust from penetrating to layers beneath. In the cases of Kevlar(Registered TradeMark) and Orthofabric this was accomplished by the addition of a silicone layer. In the case of Tyvek , the paper structure was dense enough to block dust transport. The least abrasive damage was suffered by the Tyvek(Registered TradeMark). This was thought to be due in large part to its non-woven paper structure. The woven structures were all abraded where the top of the weave was struck by the abrasive. Of these, the Orthofabric suffered the least wear, with both Vectran(Registered TradeMark) and Kevlar(Registered TradeMark) suffering considerably more extensive filament breakage.

  8. Abrasion of eroded root dentine brushed with different toothpastes.

    PubMed

    De Menezes, Márcio; Turssi, Cecilia Pedroso; Hara, Anderson Takeo; Messias, Danielle Cristine Furtado; Serra, Mônica Campos

    2004-09-01

    This study evaluated the surface roughness change and wear provided by different dentifrices on root dentine previously exposed to erosive challenges. According to a randomized complete block design, 150 slabs of bovine root dentine (6 x 3 x 2 mm) were ground flat and polished. In an area of 4 x 3 mm on the dentine surface, specimens were submitted to five erosive/abrasive events, each one composed by: exposure to Sprite Diet or distilled water for 5 min, then to a remineralizing solution for 1 min, and simulation of 5,000 brushing strokes. Four dentifrices--regular (RE), baking soda (BS), whitening (WT) and tartar control (TC)--and distilled water (CO), used as control, were compared. Final texture and the wear depth were evaluated using a profilometer. ANOVA did not show significant interaction, indicating that the effect of dentifrices on both surface roughness change and wear did not depend on whether or not the dentine was eroded ( p>0.05). There was no difference between abrasion of eroded and sound dentine. The Tukey's test revealed that WT, BS and TC provided the highest increase in surface roughness differing from RE and CO. TC yielded the deepest wear of root dentine, whereas RE and CO, the shallowest. No significant difference in wear among BS, TC and WT were observed. Within the limitations of this study, the data showed that abrasion of both eroded and sound root dentine was dependent on the dentifrice used. PMID:15146320

  9. Shotcup petal abrasions in close range .410-caliber shotgun injuries.

    PubMed

    Dowling, G P; Dickinson, J A; Cooke, C T

    1988-01-01

    Shotcup petal abrasions centered around a shotgun wound of entrance are generally thought to occur at a range of 30 to 90 cm. A suicidal .410-caliber shotgun injury of the right eye is described in which typical petal abrasions were noted around the entrance wound. However, significant soot deposition around the wound suggested that the range of fire was less than 30 cm and perhaps closer to 15 cm. Test-firing of the weapon and ammunition used by the decedent showed some spread of the shotcup petals at a range of 7.5 cm, progressing to maximum spread at 30 to 52.5 cm. Further testing with other .410 ammunition, containing shotcups, confirmed the spread of shotcup petals at ranges less than 30 cm, irrespective of manufacturer, shotshell length, and birdshot size. When a variety of shotguns were tested, it was found that one weapon with a very short barrel and cylinder bore did not exhibit petal spread until a range of 30 cm was reached. The remaining shotguns, with longer barrels and full choke, all demonstrated definite petal spread at a range of 12.5 cm. The long, narrow configuration of .410 shotcup petals may explain their early spread and the production of petal abrasions at ranges of less than 30 cm. PMID:3351464

  10. Investigation of Noise Level and Penetration Rate of Pneumatic Drill vis-à-vis Rock Compressive Strength and Abrasivity

    NASA Astrophysics Data System (ADS)

    Kivade, S. B.; Murthy, Ch. S. N.; Vardhan, H.

    2014-10-01

    In this paper, detailed studies were carried out to determine the influence of rock properties on the sound level produced during pneumatic drilling. Further, investigation was also carried out on the effect of thrust, air pressure and compressive strength on penetration rate and the sound level produced. For this purpose, a fabricated pneumatic drill set up available in the institute was used. Rock properties, like compressive strength and abrasivity, of various samples collected from the field were determined in the laboratory. Drilling experiments were carried out on ten different rock samples for varying thrust and air pressure values and the corresponding A-weighted equivalent continuous sound levels were measured. It was observed that, very low thrust results in low penetration rate. Even very high thrust does not produce high penetration rate at higher operating air pressures. With increase in thrust beyond the optimum level, the penetration rate starts decreasing and causes the drill bit to `stall'. Results of the study show that penetration rate and sound level increases with increase in the thrust level. After reaching the maximum, they start decreasing despite the increase of thrust. The main purpose of the study is to develop a general prediction model and to investigate the relationships between sound level produced during drilling and physical properties such as uniaxial compressive strength and abrasivity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of predictor variables.

  11. Face powder poisoning

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002700.htm Face powder poisoning To use the sharing features on this page, please enable JavaScript. Face powder poisoning occurs when someone swallows or breathes ...

  12. Composite powder particles

    NASA Technical Reports Server (NTRS)

    Parker, Donald S. (Inventor); MacDowell, Louis G. (Inventor)

    2009-01-01

    A liquid coating composition including a coating vehicle and composite powder particles disposed within the coating vehicle. Each composite powder particle may include a magnesium component, a zinc component, and an indium component.

  13. Precision powder feeder

    DOEpatents

    Schlienger, M. Eric; Schmale, David T.; Oliver, Michael S.

    2001-07-10

    A new class of precision powder feeders is disclosed. These feeders provide a precision flow of a wide range of powdered materials, while remaining robust against jamming or damage. These feeders can be precisely controlled by feedback mechanisms.

  14. The abrasive wear of plasma sprayed nanoscale tungsten carbide-cobalt (WC-Co)

    NASA Astrophysics Data System (ADS)

    Tewksbury, Graham Alfred

    Thermal spray coatings composed of a variety of carbide sizes and cobalt contents were sprayed with a high energy plasma spray system. The size of the carbides used fell into three rough groupings, micrometer scale carbides (1--2 mum), submicrometer (700--300 nm), and nanoscale (≈100 nm). The feedstock powder was evaluated in terms of their size distribution, external morphology, internal morphology, and initial carbide size. Two different fixtures were used in spraying to evaluate the effect of cooling rate on the wear resistance of the coatings. The microstructures of the sprayed coatings were examined using optical metallography, SEM, FESEM, TEM, XRD and chemical analysis. The coatings were evaluated in low stress abrasive wear by the ASTM G-65 Dry Sand Rubber Wheel test. Furthermore, the porosity and hardness of the coatings were evaluated. The cobalt content was found to be the predominant influence on the wear rate of the coatings. The decrease in the carbide size was not found to effect the wear rate of the coatings. Coatings sprayed on the 'hot' fixture were found to have slightly improved wear resistance as compared to coatings sprayed on the 'cold' fixture. The wear rates of the coatings were found to be a function of the WC/Co volume ratio.

  15. The effect of hydrogen peroxide on polishing removal rate in CMP with various abrasives

    NASA Astrophysics Data System (ADS)

    Manivannan, R.; Ramanathan, S.

    2009-01-01

    The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle.

  16. A Profilometric Study to Assess the Role of Toothbrush and Toothpaste in Abrasion Process

    PubMed Central

    Kumar, Sandeep; Kumar Singh, Siddharth; Gupta, Anjali; Roy, Sayak; Sareen, Mohit; Khajuria, Sarang

    2015-01-01

    Statement of the Problem Despite of many studies conducted on toothbrushes and toothpaste to find out the culprit for abrasion, there is no clear cut evidence to pin point the real cause for abrasion. Purpose An in vitro assessment of the role of different types of toothbrushes (soft/ medium/hard) in abrasion process when used in conjunction with and without a dentifrice. Materials and Method Forty five freshly extracted, sound, human incisor teeth were collected for this study. Enamel specimens of approximately 9 mm2 were prepared by gross trimming of extracted teeth using a lathe machine (Baldor 340 Dental lathe; Ohio, USA). They were mounted on separate acrylic bases. The specimens were divided into three groups, each group containing 15 mounted specimens. Group 1 specimens were brushed with soft toothbrush; Group 2 brushed with medium toothbrush and Group 3 with hard toothbrush. Initially, all the mounted specimens in each group were brushed using dentifrice and then the same procedure was repeated with water as control. Profilometric readings were recorded pre and post to tooth brushing and the differences in readings served as proxy measure to assess surface abrasion. These values were then compared to each other. Kruskal Wallis and Mann-Whitney U test were performed. Results The results showed that brushing, with water alone, caused less abrasion than when toothpaste was added (p< 0.008). When brushed with water, the harder toothbrush caused more abrasion (higher Ra-value), but when toothpaste was added, the softer toothbrush caused more abrasion (p< 0.001). Conclusion Besides supporting the fact that toothpaste is needed to create a significant abrasion, this study also showed that a softer toothbrush can cause more abrasion than harder ones. The flexibility of bristles is only secondary to abrasion process and abrasivity of dentifrice has an important role in abrasion process. PMID:26535407

  17. A comparison of the abrasiveness of six ceramic surfaces and gold.

    PubMed

    Jacobi, R; Shillingburg, H T; Duncanson, M G

    1991-09-01

    A type III gold alloy and six different ceramic surfaces were secured in an abrasion machine opposing extracted teeth to determine their relative abrasiveness and resistance to wear. The rankings of restorative materials from least abrasive to most abrasive were: gold alloy, polished; cast ceramic, polished; porcelain, polished; cast ceramic, polished and shaded; porcelain, polished and glazed; cast ceramic, cerammed skin shaded; and cast ceramic, cerammed skin unshaded. The ranking of materials from most wear-resistant to least wear-resistant was: gold alloy, cast ceramic cerammed, cast ceramic cerammed and shaded, porcelain polished, porcelain glazed, cast ceramic polished and shaded, and cast ceramic polished. PMID:1800724

  18. EMAA thermoplastic powder coatings: Shop and field application of powder coatings for aggressive environments

    SciTech Connect

    Loustaunau, P.J.; Horton, D.

    1994-12-31

    This paper deals with how Ethylene Methacrylic Acid thermoplastic powder coatings are allowing asset owners to meet tightening environmental regulations while solving some of their most difficult coating problems. It discusses the versatility of traditional shop application methods and field application/repair methods in the rail and water/waste water treatment areas. EMAA coatings typically perform well in aggressive environments due to their high flexibility and impact resistance. The material`s inherent toughness also provides for excellent abrasion resistance. EMAA demonstrates excellent resistance to chemical attack and is highly resistant to permeation by liquids. Because some aromatic, cyclic and higher aliphatic hydrocarbon solvents may cause swelling and permeate through the coating, caution should be used in immersion applications with this group of solutions.

  19. Abrasion in pyroclastic density currents: Insights from tumbling experiments

    NASA Astrophysics Data System (ADS)

    Kueppers, Ulrich; Putz, Constanze; Spieler, Oliver; Dingwell, Donald B.

    2012-01-01

    During granular mass movements of any kind, particles may interact with one another. The degree of interaction is a function of several variables including; grain-size distribution, particle concentration, density stratification and degree of fluidisation. The impact of particle interaction is additionally influenced by the relative speed, impact angle and clast temperature. Thus, both source conditions and transport-related processes are expected to influence the flow dynamics of pyroclastic density currents and their subsequent deposition. Here, we use tumbling experiments to shed light on the susceptibility of porous clasts to abrasion. We investigated the abrasion of unaltered volcanic rocks (5.7-80 vol.% porosity) from Unzen (Japan), Bezymianny (Russia) and Santorini (Greece) volcanoes as well as one synthetic analogue material, an insulating material with the trade name Foamglas® (95 vol.% porosity). Each experiment started with angular fragments generated in a jaw crusher from larger clasts. Two experimental series were performed; on samples with narrow and broader grain-size distributions, respectively. The dry samples were subject to rotational movement at constant speed and ambient temperature in a gum rotational tumbler for durations of 15, 30, 45, 60 and 120 min. The amount of volcanic ash (particles <2 mm) generated was evaluated as a function of experimental duration and sample porosity. We term “abrasion” as the ash fraction generated during the experiments. The observed increase of “abrasion” with increasing sample porosity and experimental duration is initially non-linear but becomes linear for experiments of 30 min duration or longer. For any given sample, abrasion appears to be more effective for coarser samples and larger initial mass. The observed range of ash generated in our experiments is between 1 and 35 wt.%. We find that this amount generally increases with increasing initial clast size or increasing breadth of the initial grain

  20. Heat sealable, flame and abrasion resistant coated fabric

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1983-01-01

    Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.

  1. Fine tuning the roughness of powder blasted surfaces

    NASA Astrophysics Data System (ADS)

    Wensink, Henk; Schlautmann, Stefan; Goedbloed, Martijn H.; Elwenspoek, Miko C.

    2002-09-01

    Powder blasting (abrasive jet machining) has recently been introduced as a bulk-micromachining technique for brittle materials. The surface roughness that is created with this technique is much higher (with a value of Ra between 1-2.5 μm) compared to general micromachining techniques. In this paper we study the roughness of powder blasted glass surfaces, and show how it depends on the process parameters. The roughness can also be changed after blasting by HF etching or by using a high-temperature anneal step. Roughness measurements and scanning electron microscopy images show the quantitative and qualitative changes in roughness. These post-processes will allow us to investigate the influence of surface roughness on the microsystem performance in future research.

  2. Trends in powder processing equipment

    SciTech Connect

    Sheppard, L.M.

    1993-05-01

    Spray drying is the most widely used process for producing particles. It is used in industries other than ceramics including food, chemicals, and pharmaceutical. The process involves the atomization of a liquid feed stock into a spray of droplets and contacting the droplets with hot air in a drying chamber. The sprays are produced by either rotary or nozzle atomizers. Evaporation of moisture from the droplets and formation of dry particles proceed under controlled temperature and airflow conditions. Powder is then discharged continuously from the drying chamber. Spray drying equipment is being improved to handle an ever-increasing number of applications. Several developments in particle-size reduction equipment are also described.

  3. Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

    NASA Astrophysics Data System (ADS)

    Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

    2014-10-01

    20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

  4. Effect of mechanical abrasion on the viability, disruption and germination of spores of Bacillus subtilis

    PubMed Central

    Jones, C.A.; Padula, N.L.; Setlow, P.

    2005-01-01

    Aims To elucidate the factors influencing the sensitivity of Bacillus subtilis spores to killing and disruption by mechanical abrasion, and the mechanism of stimulation of spore germination by abrasion. Methods and Results Spores of B. subtilis strains were abraded by shaking with glass beads in liquid or the dry state, and spore killing, disruption and germination were determined. Dormant spores were more resistant to killing and disruption by abrasion than were growing cells or germinated spores. However, dormant spores of the wild-type strain with or without most coat proteins removed, spores of strains with mutations causing spore coat defects, spores lacking their large depot of dipicolinic acid (DPA) and spores with defects in the germination process exhibited essentially identical rates of killing and disruption by abrasion. When spores lacking all nutrient germinant receptors were enumerated by plating directly on nutrient medium, abrasion increased the plating efficiency of these spores before killing them. Spores lacking all nutrient receptors and either of the two redundant cortex-lytic enzymes behaved similarly in this regard, but the plating efficiency of spores lacking both cortex-lytic enzymes was not stimulated by abrasion. Conclusions Dormant spores are more resistant to killing and disruption by abrasion than are growing cells or germinated spores, and neither the complete coats nor DPA are important in spore resistance to such treatments. Germination is not essential for spore killing by abrasion, although abrasion can trigger spore germination by activation of either of the spore’s cortex-lytic enzymes. Significance and Importance This work provides new insight into the mechanisms of the killing, disruption and germination of spores by abrasion and makes the surprising finding that at least much of the spore coat is not important in spore resistance to abrasion. PMID:16313421

  5. Prediction Of Abrasive And Diffusive Tool Wear Mechanisms In Machining

    NASA Astrophysics Data System (ADS)

    Rizzuti, S.; Umbrello, D.

    2011-01-01

    Tool wear prediction is regarded as very important task in order to maximize tool performance, minimize cutting costs and improve the quality of workpiece in cutting. In this research work, an experimental campaign was carried out at the varying of cutting conditions with the aim to measure both crater and flank tool wear, during machining of an AISI 1045 with an uncoated carbide tool P40. Parallel a FEM-based analysis was developed in order to study the tool wear mechanisms, taking also into account the influence of the cutting conditions and the temperature reached on the tool surfaces. The results show that, when the temperature of the tool rake surface is lower than the activation temperature of the diffusive phenomenon, the wear rate can be estimated applying an abrasive model. In contrast, in the tool area where the temperature is higher than the diffusive activation temperature, the wear rate can be evaluated applying a diffusive model. Finally, for a temperature ranges within the above cited values an adopted abrasive-diffusive wear model furnished the possibility to correctly evaluate the tool wear phenomena.

  6. Sliding-gate valve for use with abrasive materials

    DOEpatents

    Ayers, Jr., William J.; Carter, Charles R.; Griffith, Richard A.; Loomis, Richard B.; Notestein, John E.

    1985-01-01

    The invention is a flow and pressure-sealing valve for use with abrasive solids. The valve embodies special features which provide for long, reliable operating lifetimes in solids-handling service. The valve includes upper and lower transversely slidable gates, contained in separate chambers. The upper gate provides a solids-flow control function, whereas the lower gate provides a pressure-sealing function. The lower gate is supported by means for (a) lifting that gate into sealing engagement with its seat when the gate is in its open and closed positions and (b) lowering the gate out of contact with its seat to permit abrasion-free transit of the gate between its open and closed positions. When closed, the upper gate isolates the lower gate from the solids. Because of this shielding action, the sealing surface of the lower gate is not exposed to solids during transit or when it is being lifted or lowered. The chamber containing the lower gate normally is pressurized slightly, and a sweep gas is directed inwardly across the lower-gate sealing surface during the vertical translation of the gate.

  7. Attrition and abrasion models for oil shale process modeling

    SciTech Connect

    Aldis, D.F.

    1991-10-25

    As oil shale is processed, fine particles, much smaller than the original shale are created. This process is called attrition or more accurately abrasion. In this paper, models of abrasion are presented for oil shale being processed in several unit operations. Two of these unit operations, a fluidized bed and a lift pipe are used in the Lawrence Livermore National Laboratory Hot-Recycle-Solid (HRS) process being developed for the above ground processing of oil shale. In two reports, studies were conducted on the attrition of oil shale in unit operations which are used in the HRS process. Carley reported results for attrition in a lift pipe for oil shale which had been pre-processed either by retorting or by retorting then burning. The second paper, by Taylor and Beavers, reported results for a fluidized bed processing of oil shale. Taylor and Beavers studied raw, retorted, and shale which had been retorted and then burned. In this paper, empirical models are derived, from the experimental studies conducted on oil shale for the process occurring in the HRS process. The derived models are presented along with comparisons with experimental results.

  8. Multiple feed powder splitter

    DOEpatents

    Lewis, Gary K.; Less, Richard M.

    2001-01-01

    A device for providing uniform powder flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained powders are passed through the focal point of a moving high-power laser light which fuses the particles in the powder to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained powders to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained powder from between one to four hoppers and split the flow into eight tubular lines which feed the powder delivery nozzles of the DLF system.

  9. Granulation of fine powder

    DOEpatents

    Chen, Ching-Fong

    2016-08-09

    A mixture of fine powder including thorium oxide was converted to granulated powder by forming a first-green-body and heat treating the first-green-body at a high temperature to strengthen the first-green-body followed by granulation by crushing or milling the heat-treated first-green-body. The granulated powder was achieved by screening through a combination of sieves to achieve the desired granule size distribution. The granulated powder relies on the thermal bonding to maintain its shape and structure. The granulated powder contains no organic binder and can be stored in a radioactive or other extreme environment. The granulated powder was pressed and sintered to form a dense compact with a higher density and more uniform pore size distribution.

  10. Multiple feed powder splitter

    DOEpatents

    Lewis, Gary K.; Less, Richard M.

    2002-01-01

    A device for providing uniform powder flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained powders are passed through the focal point of a moving high-power laser light which fuses the particles in the powder to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained powders to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained powder from between one to four hoppers and split the flow into eight tubular lines which feed the powder delivery nozzles of the DLF system.

  11. 21 CFR 524.1005 - Furazolidone aerosol powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... infection of superficial wounds, abrasions, lacerations, and pyogenic dermatitis. (ii) Horses. For treatment or prevention of bacterial infection of superficial wounds, abrasions, lacerations, and following... infection of superficial wounds, abrasions, and lacerations caused by Staphylococcus aureus,...

  12. Cow dung powder poisoning.

    PubMed

    Sherfudeen, Khaja Mohideen; Kaliannan, Senthil Kumar; Dammalapati, Pavan Kumar

    2015-11-01

    Cow dung, which has germicidal property, was used in ancient days to clean living premises in South India. Nowadays, people are using commercially available synthetic cow dung powder. It is locally known as "saani powder" in Tamil Nadu. It is freely available in homes and is sometimes accidentally consumed by children. It is available in two colors - yellow and green. Cow dung powder poisoning is common in districts of Tamil Nadu such as Coimbatore, Tirupur, and Erode. We report two cases of yellow cow dung powder poisoning from our hospital. PMID:26730123

  13. Cotton Seedling Injury and Recovery from Wind Blown Sand Abrasion: I. Duration of Exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of crops are exposed to wind blown sand abrasion injury each year and in many instances the damage is thought to be sufficiently severe to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton seedlings. Seedlings of...

  14. Cutting Tools, Files and Abrasives. Pre-Apprenticeship Phase 1 Training.

    ERIC Educational Resources Information Center

    Lane Community Coll., Eugene, OR.

    This self-paced student training module on cutting tools, files, and abrasives is one of a number of modules developed for Pre-apprenticeship Phase 1 Training. Purpose of the module is to enable students to identify and explain the proper use and care of various knives, saws, snips, chisels, and abrasives. The module may contain some or all of the…

  15. Process Monitoring Evaluation and Implementation for the Wood Abrasive Machining Process

    PubMed Central

    Saloni, Daniel E.; Lemaster, Richard L.; Jackson, Steven D.

    2010-01-01

    Wood processing industries have continuously developed and improved technologies and processes to transform wood to obtain better final product quality and thus increase profits. Abrasive machining is one of the most important of these processes and therefore merits special attention and study. The objective of this work was to evaluate and demonstrate a process monitoring system for use in the abrasive machining of wood and wood based products. The system developed increases the life of the belt by detecting (using process monitoring sensors) and removing (by cleaning) the abrasive loading during the machining process. This study focused on abrasive belt machining processes and included substantial background work, which provided a solid base for understanding the behavior of the abrasive, and the different ways that the abrasive machining process can be monitored. In addition, the background research showed that abrasive belts can effectively be cleaned by the appropriate cleaning technique. The process monitoring system developed included acoustic emission sensors which tended to be sensitive to belt wear, as well as platen vibration, but not loading, and optical sensors which were sensitive to abrasive loading. PMID:22163477

  16. Effect of canopy leaf distribution on sand transport and abrasion energy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During times when crop canopies are short or sparse, wind erosion can uncover plant roots, deplete the soil resource, and damage plants by abrasion and desiccation. Few studies have considered the effects of position and number of leaves on sand transport and the distribution of the sand abrasion en...

  17. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-05

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of ternary mixtures consisting of: Ni powder, Cu powder, and Al powder, Ni powder, Cr powder, and Al powder; Ni powder, W powder and Al powder; Ni powder, V powder, and Al powder; Ni powder, Mo powder, and Al powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  18. Hybrid organic/inorganic coatings for abrasion resistance on plastic and metal substrates

    SciTech Connect

    Wen, J.; Jordens, K.; Wilkes, G.L.

    1996-12-31

    Novel abrasion resistant coatings have been successfully prepared by the sol-gel method. These materials are spin coated onto bisphenol-A polycarbonate, diallyl diglycol carbonate resin (CR-39) sheet, aluminum, and steel substrates and are thermally cured to obtain a transparent coating of a few microns in thickness. Following the curing, the abrasion resistance is measured and compared with an uncoated control. It was found that these hybrid organic/inorganic networks partially afford excellent abrasion resistance to the polycarbonate substrates investigated. In addition to having excellent abrasion resistance comparable to current commercial coatings, some newly developed systems are also UV resistant. Similar coating formulations applied to metals can greatly improve the abrasion resistance despite the fact that the coatings are lower in density than their substrates.

  19. Electron Microscopy Abrasion Analysis of Candidate Fabrics for Planetary Space Suit Protective Overgarment Application

    NASA Technical Reports Server (NTRS)

    Hennessy, Mary J.

    1992-01-01

    The Electron Microscopy Abrasion Analysis of Candidate Fabrics for Planetary Space Suit Protective Overgarment Application is in support of the Abrasion Resistance Materials Screening Test. The fundamental assumption made for the SEM abrasion analysis was that woven fabrics to be used as the outermost layer of the protective overgarment in the design of the future, planetary space suits perform best when new. It is the goal of this study to determine which of the candidate fabrics was abraded the least in the tumble test. The sample that was abraded the least will be identified at the end of the report as the primary candidate fabric for further investigation. In addition, this analysis will determine if the abrasion seen by the laboratory tumbled samples is representative of actual EVA Apollo abrasion.

  20. A review of engineering control technology for exposures generated during abrasive blasting operations.

    PubMed

    Flynn, Michael R; Susi, Pam

    2004-10-01

    This literature review presents information on measures for controlling worker exposure to toxic airborne contaminants generated during abrasive blasting operations occurring primarily in the construction industry. The exposures of concern include respirable crystalline silica, lead, chromates, and other toxic metals. Unfortunately, silica sand continues to be widely used in the United States as an abrasive blasting medium, resulting in high exposures to operators and surrounding personnel. Recently, several alternative abrasives have emerged as potential substitutes for sand, but they seem to be underused Some of these abrasives may pose additional metal exposure hazards. In addition, several new and improved technologies offer promise for reducing or eliminating exposures; these include wet abrasive blasting, high-pressure water jetting, vacuum blasting, and automated/robotic systems. More research, particularly field studies, is needed to evaluate control interventions in this important and hazardous operation. PMID:15631059

  1. High grade abrasive product development from virtified industrial waste

    SciTech Connect

    Blume, R.D.; Drummond, C.H. III; Sarko, A.

    1996-12-31

    Recent developments in environmental legislation, as well as economic incentives such as the increasing cost of landfilling, have led to a paradigm shift away from encapsulation of hazardous waste. The current focus is recycling and product development utilizing industrial waste as raw materials. Current research has targeted the development of high grade abrasive (Vickers hardness (VHN) > 1000 kgF/mm{sup 2}) for blasting and buffing and polishing applications. In addition to product specific physical properties, the developed formulations must also have processing characteristics necessary for vitrification using a high temperature product burner developed by Seiler Pollution Control Systems, as well as the necessary resistance to leaching of EPA regulated hazardous components. Current work has led to the development of formulations with high VHN (950 kgF/mm{sup 2}), acceptable chemical durability, and high mechanical durability utilizing electric arc furnace dust (KO61) and foundry sand as the major components.

  2. Wire blade development for Fixed Abrasive Slicing Technique (FAST) slicing

    NASA Technical Reports Server (NTRS)

    Khattak, C. P.; Schmid, F.; Smith, M. B.

    1982-01-01

    A low cost, effective slicing method is essential to make ingot technology viable for photovoltaics in terrestrial applications. The fixed abrasive slicing technique (FAST) combines the advantages of the three commercially developed techniques. In its development stage FAST demonstrated cutting effectiveness of 10 cm and 15 cm diameter workpieces. Wire blade development is still the critical element for commercialization of FAST technology. Both impregnated and electroplated wire blades have been developed; techniques have been developed to fix diamonds only in the cutting edge of the wire. Electroplated wires show the most near term promise and this approach is emphasized. With plated wires it has been possible to control the size and shape of the electroplating, it is expected that this feature reduces kerf and prolongs the life of the wirepack.

  3. Fatigue Testing of Abrasive Water Jet Cut Titanium

    SciTech Connect

    Hovanski, Yuri; Dahl, Michael E.; Williford, Ralph E.

    2009-06-08

    Battelle Memorial Institute as part of its U.S. Department of Energy (USDOE) Contract No. DE-AC05-76RL01830 to operate the Pacific Northwest National Laboratory (PNNL) provides technology assistance to qualifying small businesses in association with a Technology Assistance Program (TAP). Qualifying companies are eligible to receive a set quantity of labor associated with specific technical assistance. Having applied for a TAP agreement to assist with fatigue characterization of Abrasive Water Jet (AWJ) cut titanium specimens, the OMAX Corporation was awarded TAP agreement 09-02. This program was specified to cover dynamic testing and analysis of fatigue specimens cut from titanium alloy Ti-6%Al-4%V via AWJ technologies. In association with the TAP agreement, a best effort agreement was made to characterize fatigue specimens based on test conditions supplied by OMAX.

  4. Quantitative modeling of facet development in ventifacts by sand abrasion

    NASA Astrophysics Data System (ADS)

    Várkonyi, Péter L.; Laity, Julie E.; Domokos, Gábor

    2016-03-01

    We use a quantitative model to examine rock abrasion by direct impacts of sand grains. Two distinct mechanisms are uncovered (unidirectional and isotropic), which contribute to the macro-scale morphological characters (sharp edges and flat facets) of ventifacts. It is found that facet formation under conditions of a unidirectional wind relies on certain mechanical properties of the rock material, and we confirm the dominant role of this mechanism in the formation of large ventifacts. Nevertheless small ventifacts may also be shaped to polyhedral shapes in a different way (isotropic mechanism), which is not sensitive to wind characteristics nor to rock material properties. The latter mechanism leads to several 'mature' shapes, which are surprisingly analogous to the morphologies of typical small ventifacts. Our model is also able to explain certain quantitative laboratory and field observations, including quick decay of facet angles of ventifacts followed by stabilization in the range 20-30°.

  5. Cover and Erosion Asymmetry in Saltation-Abrasion

    NASA Astrophysics Data System (ADS)

    Stark, C. P.; Parker, G.

    2014-12-01

    Erosion in bedrock-floored rivers is both driven and limited by the amount of sediment transported along the bed. Some sediment boosts wear rates, whereas too much generates a protective cover. This phenomenon determines the shape of river channels in a variety of landscapes and limits how fast they evolve. Here we reevaluate data from a well-known bedrock wear experiment to throw new light on how the saltation-abrasion process. Instead of a symmetric form for erosion versus sediment flux relative to transport capacity, we find the erosion rate peak shifts towards lower sediment fluxes when blocking of oblique saltation trajectories is taken into account. The theoretical context for this reevaluation is a cover-saltation-abrasion model, based on queueing theory (QT), for bedload transport over a planar bedrock bed. The QT approach provides some clarity in the stochastic treatment of granular impacts and cover, and generates closed-form solutions for wear rate in terms of sediment flux and simplified saltation geometry. Applied to the Sklar & Dietrich (2001) experiments in a very small recirculating flume, the two-parameter QT model fits the observed relation between erosion rate and sediment load, infers sediment flux as a function of load, admits non-negligible wear rates for a mean sediment depth of one grain, i.e., for full cover on average, but also suggests that bedrock erosion is blocked at >=50% instantaneous cover. The QT model makes testable predictions for future laboratory experiments and highlights the need for specific improvements in more comprehensive treatments of bedrock erosion and cover.

  6. Compaction of Titanium Powders

    SciTech Connect

    Stephen J. Gerdemann; Paul D. Jablonski

    2010-11-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 μm, <75 μm, and < 45 μm; two different sizes of a hydride-dehydride [HDH] <75 μm and < 45 μm; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  7. Sintering titanium powders

    SciTech Connect

    Gerdemann, Stephen J.; Alman, David E.

    2005-09-01

    Recently, there has been renewed interest in low-cost titanium. Near-net-shape powder metallurgy offers the potential of manufacturing titanium articles without costly and difficult forming and machining operations; hence, processing methods such as conventional press-and-sinter, powder forging and powder injection molding are of interest. The sintering behavior of a variety of commercial and experimental titanium powders was studied. Commercial powders were acquired that were produced different routes: (i) sponge fines from the primary titanium processing; (ii) via the hydride-dehydride process; and (iii) gas atomization. The influence of vacuum sintering time (0.5 to 32 hrs) and temperature (1200, 1275 or 1350°C) on the microstructure (porosity present) of cold pressed powders was studied. The results are discussed in terms of the difference in powder characteristics, with the aim of identify the characteristics required for full density via press-and-sinter processing. Near-net-shape tensile bars were consolidated via cold pressed and sintered. After sintering, a sub-set of the tensile bars was hot-isostatic pressed (HIPed). The microstructure and properties of the bars were compared in the sintered and HIPed conditions.

  8. Quantitative image analysis for evaluating the abrasion resistance of nanoporous silica films on glass

    NASA Astrophysics Data System (ADS)

    Nielsen, Karsten H.; Karlsson, Stefan; Limbach, Rene; Wondraczek, Lothar

    2015-12-01

    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.

  9. Microstructural effects in abrasive wear. Third annual progress report, August 12, 1983-August 14, 1984

    SciTech Connect

    Kosel, T.H.

    1984-08-14

    The two major goals of the project are to improve our understanding of the mechanisms of carbide removal and of the role of matrix properties in abrasion. In the area of carbide removal mechanisms, progress this year has included completion of the fixed-depth scratch test apparatus and its use to demonstrate the occurrence of gross carbide cracking under fixed-depth conditions; comparable cracking does not occur under fixed-load conditions at a similar mean load. A high-stress abrasion system has been constructed and tested which will facilitate studies of abrasion under conditions similar to those produced by the fixed-depth scratch test system. Analysis of the work on the size effect in abrasion of dual-phase alloys has been completed. The largest single item in this year's proposed work in a study of the abrasion resistance and mechanisms of material removal in model alloys having second-phase particles (SPP's) with varying fracture properties. In the area of the effects of matrix properties on abrasion, the majority of the effort this year has centered on transmission electron microscopy of the subsurface deformation microstructures developed during abrasion.

  10. 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

  11. Relationships Between Abrasive Wear, Hardness, and Surface Grinding Characteristics of Titanium-Based Metal Matrix Composites

    SciTech Connect

    Blau, Peter Julian; Jolly, Brian C

    2009-01-01

    The objective of this work was to support the development of grinding models for titanium metal-matrix composites (MMCs) by investigating possible relationships between their indentation hardness, low-stress belt abrasion, high-stress belt abrasion, and the surface grinding characteristics. Three Ti-based particulate composites were tested and compared with the popular titanium alloy Ti-6Al-4V. The three composites were a Ti-6Al-4V-based MMC with 5% TiB{sub 2} particles, a Ti-6Al-4V MMC with 10% TiC particles, and a Ti-6Al-4V/Ti-7.5%W binary alloy matrix that contained 7.5% TiC particles. Two types of belt abrasion tests were used: (a) a modified ASTM G164 low-stress loop abrasion test, and (b) a higher-stress test developed to quantify the grindability of ceramics. Results were correlated with G-ratios (ratio of stock removed to abrasives consumed) obtained from an instrumented surface grinder. Brinell hardness correlated better with abrasion characteristics than microindentation or scratch hardness. Wear volumes from low-stress and high-stress abrasive belt tests were related by a second-degree polynomial. Grindability numbers correlated with hard particle content but were also matrix-dependent.

  12. Linear abrasion of a titanium superhydrophobic surface prepared by ultrafast laser microtexturing

    NASA Astrophysics Data System (ADS)

    Steele, Adam; Nayak, Barada K.; Davis, Alexander; Gupta, Mool C.; Loth, Eric

    2013-11-01

    A novel method of fabricating titanium superhydrophobic surfaces by ultrafast laser irradiation is reported. The ultrafast laser irradiation creates self-organized microstructure superimposed with nano-scale roughness, after which a fluoropolymer coating is applied to lower the surface energy of the textured surface and achieve superhydrophobicity. The focus of this study is to investigate abrasion effects on this mechanically durable superhydrophobic surface. The mechanical durability is analyzed with linear abrasion testing and microscopy imaging. Linear abrasion tests indicate that these surfaces can resist complete microstructure failure up to 200 abrasion cycles and avoid droplet pinning up to ten abrasion cycles at 108.4 kPa applied pressure, which roughly corresponds to moderate to heavy sanding or rubbing in the presence of abrasive particles. The wear mechanisms are also investigated and the primary mechanism for this system is shown to be abrasive wear with fatigue by repeated plowing. Although these results demonstrate an advancement in mechanical durability over the majority of existing superhydrophobic surfaces, it exemplifies the challenge in creating superhydrophobic surfaces with suitable mechanical durability for harsh applications, even when using titanium.

  13. Influence of Corrosion on the Abrasion of Cutter Steels Used in TBM Tunnelling

    NASA Astrophysics Data System (ADS)

    Espallargas, N.; Jakobsen, P. D.; Langmaack, L.; Macias, F. J.

    2015-01-01

    Abrasion on tunnel boring machine (TBM) cutters may be critical in terms of project duration and costs. Several researchers are currently studying the degradation of TBM cutter tools used for excavating hard rock, soft ground and loose soil. So far, the primary focus of this research has been directed towards abrasive wear. Abrasive wear is a very common process in TBM excavation, but with a view to the environment in which the tools are working, corrosion may also exert an influence. This paper presents a selection of techniques that can be used to evaluate the influence of corrosion on abrasion on TBM excavation tools. It also presents the influence of corrosion on abrasive wear for some initial tests, with constant steel and geomaterial and varying properties of the excavation fluids (soil conditioners, anti-abrasion additives and water). The results indicate that the chloride content in the water media greatly influences the amount of wear, providing evidence of the influence of corrosion on the abrasion of the cutting tools. The presence of conditioning additives tailored to specific rock or soil conditions reduces wear. However, when chloride is present in the water, the additives minimise wear rates but fail to suppress corrosion of the cutting tools.

  14. Ceramic powder compaction

    SciTech Connect

    Glass, S.J.; Ewsuk, K.G.; Mahoney, F.M.

    1995-12-31

    With the objective of developing a predictive model for ceramic powder compaction we have investigated methods for characterizing density gradients in ceramic powder compacts, reviewed and compared existing compaction models, conducted compaction experiments on a spray dried alumina powder, and conducted mechanical tests and compaction experiments on model granular materials. Die filling and particle packing, and the behavior of individual granules play an important role in determining compaction behavior and should be incorporated into realistic compaction models. These results support the use of discrete element modeling techniques and statistical mechanics principals to develop a comprehensive model for compaction, something that should be achievable with computers with parallel processing capabilities.

  15. Optical-model abrasion cross sections for high-energy heavy ions

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.

    1981-01-01

    Within the context of eikonal scattering theory, a generalized optical model potential approximation to the nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision model to predict abrasion cross sections for relativistic projectile heavy ions. Unlike the optical limit of Glauber theory, which cannot be used for very light nuclei, the abrasion formalism is valid for any projectile target combination at any incident kinetic energy for which eikonal scattering theory can be utilized. Results are compared with experimental results and predictions from Glauber theory.

  16. Plasma-polymerized coating for polycarbonate: Single-layer, abrasion resistant, and antireflection

    NASA Technical Reports Server (NTRS)

    Wydeven, Theodore

    1991-01-01

    Plasma-polymerized vinyl trimethoxy silane films were deposited on transparent polycarbonate substrates. The adherent, clear films protected the substrates from abrasion and also served as antireflection coatings. Post-treatment of the vinyl trimethoxy silane films in an oxygen glow discharge further improved their abrasion resistance. The coatings were characterized by elemental analysis of the bulk, ESCA analysis of the surface, transmission, thickness, abrasion resistance, haze, and adhesion. This patented process is currently used by the world's largest manufacturers of non-prescription sunglasses to protect the plastic glasses from scratching and thereby to increase their useful lifetime.

  17. Optical-model abrasion cross sections for high-energy heavy ions

    SciTech Connect

    Townsend, L.W.

    1981-07-01

    Within the context of eikonal scattering theory, a generalized optical model potential approximation to the nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision model to predict abrasion cross sections for relativistic projectile heavy ions. Unlike the optical limit of Glauber theory, which cannot be used for very light nuclei, the abrasion formalism is valid for any projectile target combination at any incident kinetic energy for which eikonal scattering theory can be utilized. Results are compared with experimental results and predictions from Glauber theory.

  18. High Resolution Laser Scanning Techniques for Rock Abrasion and Texture Analyses on Mars and Earth

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Razdan, A.; Greeley, R.; Laity, J. E.

    2004-01-01

    Aeolian abrasion is operative in many arid locations on Earth and is probably the dominant rock erosion process in the current Martian environment. Therefore, understanding the controlling parameters and rates of aeolian abrasion provides 1) insight into the stability of rocks on planetary surfaces and the environments under which the rocks abrade, and 2) a link between ventifact (a rock abraded by windblown particles) morphology and: a) abrasion conditions, b) possible ancient environments under which the rocks were abraded, and c) rock properties. promising and we plan further investigations in the wind tunnel and field. Our intent here is to discuss the basic technique, initial results, and upcoming plans.

  19. Target correlation effects on neutron-nucleus total, absorption, and abrasion cross sections

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Townsend, Lawrence W.; Wilson, John W.

    1991-01-01

    Second order optical model solutions to the elastic scattering amplitude were used to evaluate total, absorption, and abrasion cross sections for neutron nucleus scattering. Improved agreement with experimental data for total and absorption cross sections is found when compared with first order (coherent approximation) solutions, especially below several hundred MeV. At higher energies, the first and second order solutions are similar. There are also large differences in abrasion cross section calculations; these differences indicate a crucial role for cluster knockout in the abrasion step.

  20. Abrasion of heavy-duty coated steel pipes by sediment transport

    SciTech Connect

    Kariyazono, Yoshihisa; Miyajima, Yoshihiro; Sato, Koichi; Yamashita, Toshihiko, Yamashita; Saeki, Hiroshi

    1994-12-31

    Heavy-duty coatings are standard treatment for steel pipe piles in coastal zones to prevent corrosion. Large amounts of sand sometimes drift around piles by the action of waves. Coatings undergo abrasion by collision of sand particles. Authors carried out experiments by a large scale U-shaped tube which generated a strong oscillatory flow with sand drift and numerical analysis of collision of the particles. Authors found out the abrasion rate of pile is nearly proportional to the collision energy of the particles. Abrasion rate of polyethylene and elastic polyurethane coatings were lower than those of other materials.

  1. Three-Body Abrasion Testing Using Lunar Dust Simulants to Evaluate Surface System Materials

    NASA Technical Reports Server (NTRS)

    Kobrick, Ryan L.; Budinski, Kenneth G.; Street, Kenneth W., Jr.; Klaus, David M.

    2010-01-01

    Numerous unexpected operational issues relating to the abrasive nature of lunar dust, such as scratched visors and spacesuit pressure seal leaks, were encountered during the Apollo missions. To avoid reoccurrence of these unexpected detrimental equipment problems on future missions to the Moon, a series of two- and three-body abrasion tests were developed and conducted in order to begin rigorously characterizing the effect of lunar dust abrasiveness on candidate surface system materials. Two-body scratch tests were initially performed to examine fundamental interactions of a single particle on a flat surface. These simple and robust tests were used to establish standardized measurement techniques for quantifying controlled volumetric wear. Subsequent efforts described in the paper involved three-body abrasion testing designed to be more representative of actual lunar interactions. For these tests, a new tribotester was developed to expose samples to a variety of industrial abrasives and lunar simulants. The work discussed in this paper describes the three-body hardware setup consisting of a rotating rubber wheel that applies a load on a specimen as a loose abrasive is fed into the system. The test methodology is based on ASTM International (ASTM) B611, except it does not mix water with the abrasive. All tests were run under identical conditions. Abraded material specimens included poly(methyl methacrylate) (PMMA), hardened 1045 steel, 6061-T6 aluminum (Al) and 1018 steel. Abrasives included lunar mare simulant JSC- 1A-F (nominal size distribution), sieved JSC-1A-F (<25 m particle diameter), lunar highland simulant NU-LHT-2M, alumina (average diameter of 50 m used per ASTM G76), and silica (50/70 mesh used per ASTM G65). The measured mass loss from each specimen was converted using standard densities to determine total wear volume in cm3. Abrasion was dominated by the alumina and the simulants were only similar to the silica (i.e., sand) on the softer materials of

  2. Abrasive wear by coal-fueled diesel engine and related particles

    SciTech Connect

    Ives, L.K.

    1992-09-01

    The development of commercially viable diesel engines that operate directly on pulverized coal-fuels will require solution to the problem of severe abrasive wear. The purpose of the work described in this report was to investigate the nature of the abrasive wear problem. Analytical studies were carried out to determine the characteristics of the coal-fuel and associated combustion particles responsible for abrasion. Laboratory pinon-disk wear tests were conducted on oil-particle mixtures to determine the relationship between wear rate and a number of different particle characteristics, contact parameters, specimen materials properties, and other relevant variables.

  3. Gelcasting superalloy powders

    SciTech Connect

    Janney, M.A.

    1995-12-31

    Gelcasting is a process for forming inorganic powders into complex shapes. It was originally developed for ceramic powders. A slurry of powder and a monomer solution is poured in to mold and polymerized in-situ to form gelled parts. Typically, only 2-4 wt % Polymer is used. The process has both aqueous and nonaqueous versions. Gelcasting is a generic process and has been used to produce ceramic parts from over a dozen different ceramic compositions ranging from alumina-based refractories to high-performance silicon nitride. Recently, gelcasting has been applied to forming superalloy powders into complex shapes. This application has posed several challenges not previously encountered in ceramics. In particular, problems were caused by the larger particle size and the higher density of the particles. Additional problems were encountered with binder removal. How these problems were overcome will be described.

  4. Magnetically responsive enzyme powders

    NASA Astrophysics Data System (ADS)

    Pospiskova, Kristyna; Safarik, Ivo

    2015-04-01

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (-20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties.

  5. POWDER COAT APPLICATIONS

    EPA Science Inventory

    The report discusses an investigation of critical factors that affect the use of powder coatings on the environment, cost, quality, and production. The investigation involved a small business representative working with the National Defense Center for Environmental Excellence (ND...

  6. Pyrotechnic filled molding powder

    DOEpatents

    Hartzel, Lawrence W.; Kettling, George E.

    1978-01-01

    The disclosure relates to thermosetting molding compounds and more particularly to a pyrotechnic filled thermosetting compound comprising a blend of unfilled diallyl phthalate molding powder and a pyrotechnic mixture.

  7. Talcum powder poisoning

    MedlinePlus

    ... powder As a filler in street drugs, like heroin Other products may also contain talc. ... have developed serious lung damage and cancer. Injecting heroin that contains talc into a vein may lead ...

  8. Surface assessment and modification of concrete using abrasive blasting

    NASA Astrophysics Data System (ADS)

    Millman, Lauren R.

    Composite systems are applied to concrete substrates to strengthen and extend the service life. Successful restoration or rehabilitation requires surface preparation prior to the application of the overlay. Surface coatings, waterproofing systems, and other external surface applications also require surface preparation prior to application. Abrasive blast media is often used to clean and uniformly roughen the substrate. The appropriate surface roughness is necessary to facilitate a strong bond between the existing substrate and overlay. Thus, surface modification using abrasive blast media (sand and dry ice), their respective environmental effects, surface roughness characterization prior to and after blasting, and the adhesion between the substrate and overlay are the focus of this dissertation. This dissertation is comprised of an introduction, a literature review, and four chapters, the first of which addresses the environmental effects due to abrasive blasting using sand, water, and dry ice. The assessment considered four response variables: carbon dioxide (CO2) emissions, fuel and energy consumption, and project duration. The results indicated that for sand blasting and water jetting, the primary factor contributing to environmental detriment was CO22 emissions from vehicular traffic near the construction site. The second chapter is an analysis of the International Concrete Repair Institute's (ICRI) concrete surface profiles (CSPs) using 3-D optical profilometry. The primary objective was to evaluate the suitability of approximating the 3-D surface (areal) parameters with those extracted from 2-D (linear) profiles. Four profile directions were considered: two diagonals, and lines parallel and transverse to the longitudinal direction of the mold. For any CSP mold, the estimation of the 3-D surface roughness using a 2-D linear profile resulted in underestimation and overestimation errors exceeding 50%, demonstrating the inadequacy of 2-D linear profiles to

  9. Powder Diffraction: By Decades

    NASA Astrophysics Data System (ADS)

    David, William I. F.

    This introductory chapter reviews the first 100 years of powder diffraction, decade by decade, from the earliest X-ray powder diffraction measurements of the crystal structure of graphite through to the diversity and complexity of twenty-first century powder diffraction. Carbon features as an illustrative example throughout the discussion of these ten decades from graphite and the disorder of carbon black through to lonsdaleite, the elusive hexagonal polymorph of diamond, and C60, the most symmetrical of molecules. Electronics and computing have played a leading role in the development of powder diffraction, particularly over the past 60 years, and the Moore's Law decade-by-decade rise in computing power is clear in the increasing complexity of powder diffraction experiments and material systems that can be studied. The chapter concludes with a final discussion of decades - the four decades of length-scale from the ångstrom to the micron that not only represent the domain of powder diffraction but are also the distances that will dominate twenty-first century science and technology.

  10. Abrasive jet micro-machining of polymeric materials

    NASA Astrophysics Data System (ADS)

    Hailu, Getu

    In the abrasive jet micro-machining (AJM) process, a jet of small particles is directed through an erosion resistant mask opening so that micro-sized features (i.e., micro-channels, holes, etc.) can be machined for the fabrication of micro-devices such as micro-fluidic and micro-electro-mechanical-systems (MEMS). Polymeric materials and elastomers have found applications in a wide variety of micro-devices. This thesis investigates the AJM of such materials, addressing the major challenges that must be overcome in order for the process to gain wider acceptance in industry. The thesis first presents a novel cryogenically assisted abrasive jet micro-machining (CAJM) technique that enables the micro-machining of elastomers such as polydimethylsiloxane (PDMS) that cannot be machined at room temperature. It was found that the erosion rate during CAJM is greatly increased, and the degree of particle embedment greatly decreased, compared to room temperature experiments. A finite element (FE) analysis was used to investigate the relationships between erosion, the heat transfer of the cooling jet and the resulting target temperature during the CAJM of channels in PDMS. The analysis illustrated the asymmetric nature of the cooling with much more cooling occurring towards the trailing edge of the jet. It was found that the predicted shape of the evolving machined surface profiles was improved significantly when a FE model was used to account for thermal distortion occurring during the CAJM process. An unwanted consequence of the AJM of polymeric materials was found to be particle embedding. Criteria leading to the embedding of spherical and angular particles in such materials were identified and modelled using rigid plastic analyses. It was found that the likelihood of embedding was proportional to the static coefficient of friction between the particle and the target for angular particles, and the depth of penetration for spherical particles. Scanning electron microscopy with

  11. Investigation of machining damage and tool wear resulting from drilling powder metal aluminum alloy

    SciTech Connect

    Fell, H.A.

    1997-05-01

    This report documents the cutting of aluminum powder metallurgy (PM) parts for the North Carolina Manufacturing Extension Partnership. The parts, an aluminum powder metal formulation, were supplied by Sinter Metals Inc., of Conover, North Carolina. The intended use of the alloy is for automotive components. Machining tests were conducted at Y-12 in the machine shop of the Skills Demonstration Center in Building 9737. Testing was done on June 2 and June 3, 1997. The powder metal alloy tested is very abrasive and tends to wear craters and produce erosion effects on the chip washed face of the drills used. It also resulted in huge amounts of flank wear and degraded performance on the part of most drills. Anti-wear coatings on drills seemed to have an effect. Drills with the coating showed less wear for the same amount of cutting. The usefulness of coolants and lubricants in reducing tool wear and chipping/breakout was not investigated.

  12. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    1995-02-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography. (Contains a minimum of 115 citations and includes a subject term index and title list.)

  13. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    1997-01-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  14. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    1995-12-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  15. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent database). Published Search

    SciTech Connect

    Not Available

    1993-05-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography. (Contains a minimum of 97 citations and includes a subject term index and title list.)

  16. Dental Abrasion of Incisor caused by a Babies' Dummy Clip: A Case Report.

    PubMed

    Doğramacı, Esma J; Rossi-Fedele, Giampiero

    2015-09-01

    Tooth surface loss (TSL), the non-carious loss of tooth tissue, is considered pathological if the teeth involved experience sensitivity and pain, are functionally compromised or they detract from the patient's appearance. TSL is a common clinical finding in many patient groups, although differences between the primary and permanent dentition contribute to TSL occurring at a faster rate and with worse outcomes in the primary dentition. This case report presents localized abrasion and associated apical periodontitis affecting a single primary tooth in a 2-year-old infant following the misuse of a babies' dummy clip whilst teething. Abrasion is rare in the primary dentition. CPD/CLINICAL RELEVANCE: This article highlights an unusual presentation of dental abrasion affecting the primary dentition caused by a previously unreported foreign object; abrasion in this case was a side-effect of soothing the discomfort of teething. PMID:26630866

  17. Demonstration experience with an abrasive blasting technique for decontaminating concrete pads

    SciTech Connect

    Devgun, J.S. ); Land, R.R. ); Doane, R.W. )

    1990-01-01

    A demonstration was performed for decontaminating a radioactivity contaminated concrete pad with a portable abrasive blasting system. The system utilizes a rotating blast wheel that scours the concrete surface with metal abrasive. The metal abrasive, pulverized concrete dust, and contaminants rebound into a separator chamber. The reusable metal abrasive is recycled, and the pulverized media are removed to an integral dust collection system. The exhaust is HEPA filtered to minimize release of airborne contaminants. However, the technique had limited success in reducing contamination around the cracks and seams in the concrete where the higher activity levels of contamination were detected during the radiological survey before the cleanup. The technique can be successful and cost-effective in decontaminating large areas of low contamination; however, careful characterization and planning are necessary. 3 refs., 3 figs., 1 tabs.

  18. Abrasion resistance of biaxially oriented polypropylene films coated with nanocomposite hard coatings

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Zhu, Yaofeng; Fu, Yaqin

    2013-11-01

    KMnO4-treated, functionalized, biaxially oriented polypropylene (BOPP) films coated with nano-silica hybrid material were synthesized. The abrasion resistance of the films was examined using a reciprocating fabric abrasion tester. Functional groups were confirmed by Fourier-transform infrared spectroscopy. Contact angle measurements were performed on the BOPP film surface to quantify the effectiveness of the functionalization. Results indicate that the abrasion resistance and roughness of the composite film were significantly affected by the modification of the BOPP film. Water surface contact angle of the modified BOPP films decreased from 90.1° to 71.4°,when KMnO4 concentration increased from 0 M to 0.25 M. Wettability of the BOPP films clearly improved after KMnO4 treatment. Abrasion resistance of the functionalized films coated with hybrid materials improved by 27.4% compared with that of the original film.

  19. Abrasion and deformed layer formation of manganese-zinc ferrite in sliding contact with lapping tapes

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.; Tanaka, K.

    1986-01-01

    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and the deformed layers produced in single-crystal Mn-Zn ferrite simulated heads during contact with lapping tapes. The crystaline state of the head is changed drastically during the abrasion process. Crystalline states ranging from nearly amorphous to highly textured polycrystalline can be produced on the wear surface of a single-crystal Mn-Zn ferrite head. The total thickness of the deformed layer was approximately 0.8 microns. This thickness increased as the load and abrasive grit size increased. The anisotropic wear of the ferrite was found to be inversely proportional to the hardness of the wear surface. The wear was lower in the order 211 111 10 0110. The wear of the ferrite increased markedly with an increase in sliding velocity and abrasive grit size.

  20. Cracks in glass electrical connector headers removed by dry blasting with fine abrasive

    NASA Technical Reports Server (NTRS)

    Eckert, R. W.

    1967-01-01

    Cracking that causes pressure leakage in glass connector headers can be alleviated by manipulating the pin bridgewire connectors. This initiates the surface and meniscus cracks. Dry blasting the header surface with a fine abrasive then removes the cracks.

  1. Surface roughness and gloss of current CAD/CAM resin composites before and after toothbrush abrasion.

    PubMed

    Koizumi, Hiroyasu; Saiki, Osamu; Nogawa, Hiroshi; Hiraba, Haruto; Okazaki, Tomoyo; Matsumura, Hideo

    2015-01-01

    The purpose of this study was to evaluate the gloss and surface roughness behaviors of newly developed CAD/CAM composite blocks with different filler contents and characteristics. The gloss and surface roughness were quantified before and after a toothbrush dentifrice abrasion test; the results were compared to the gloss and surface roughness of a ceramic CAD/CAM block. Knoop hardness was determined before abrasion test. The results were analyzed by ANOVA, Tukey HSD, and Dunnett t test (p<0.05). The rank order of Knoop hardness was as follows: Vita Mark II>Vita Enamic>Gradia block>Shofu Block HC, Lava Ultimate≥Katana Avencia block≥Cerasmart. After toothbrush abrasion, a significant difference in the gloss unit was detected between the Shofu Block HC material and the ceramic block. The Ra and Rz of the Cerasmart and Shofu Block HC materials were significantly larger than those of the ceramic block after toothbrush abrasion. PMID:26632238

  2. Method for classifying ceramic powder

    NASA Technical Reports Server (NTRS)

    Takabe, K.

    1983-01-01

    Under the invented method, powder A of particles of less than 10 microns, and carrier powder B, whose average particle diameter is more than five times that of powder A, are premixed so that the powder is less than 40 wt.% of the total mixture, before classifying.

  3. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-19

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  4. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goval, Amit; Williams, Robert K.; Kroeger, Donald M.

    2005-06-07

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  5. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-07-29

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  6. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2004-09-14

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  7. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2005-05-10

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  8. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-26

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  9. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2004-09-28

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  10. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2005-01-25

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  11. Plasma polymerized coating for polycarbonate - Single layer, abrasion resistant, and antireflection

    NASA Technical Reports Server (NTRS)

    Wydeven, T.

    1977-01-01

    Plasma polymerized vinyltrimethoxy silane films were deposited on transparent polycarbonate substrates. The adherent, clear films protected the substrates from abrasion and also served as antireflection coatings. Posttreatment of the vinyltrimethoxy silane films in an oxygen glow discharge further improved the abrasion resistance. ESCA (electron spectroscopy for chemical analysis) and IR transmission spectra of some films were recorded, and an elemental analysis of the films was obtained.

  12. Experimental Study on Abrasive Waterjet Polishing of Hydraulic Turbine Blades

    NASA Astrophysics Data System (ADS)

    Khakpour, H.; Birglenl, L.; Tahan, A.; Paquet, F.

    2014-03-01

    In this paper, an experimental investigation is implemented on the abrasive waterjet polishing technique to evaluate its capability in polishing of surfaces and edges of hydraulic turbine blades. For this, the properties of this method are studied and the main parameters affecting its performance are determined. Then, an experimental test-rig is designed, manufactured and tested to be used in this study. This test-rig can be used to polish linear and planar areas on the surface of the desired workpieces. Considering the number of parameters and their levels, the Taguchi method is used to design the preliminary experiments. All experiments are then implemented according to the Taguchi L18 orthogonal array. The signal-to-noise ratios obtained from the results of these experiments are used to determine the importance of the controlled polishing parameters on the final quality of the polished surface. The evaluations on these ratios reveal that the nozzle angle and the nozzle diameter have the most important impact on the results. The outcomes of these experiments can be used as a basis to design a more precise set of experiments in which the optimal values of each parameter can be estimated.

  13. Gingival abrasion and plaque removal with manual versus electric toothbrushing.

    PubMed

    Niemi, M L; Ainamo, J; Etemadzadeh, H

    1986-08-01

    A clinical trial was designed to test the relative numbers of gingival lesions caused during standardized brushing of the teeth of 22 volunteer dental nurse students with a manual soft multitufted, a manual soft V-shaped, and an electric toothbrush. First, the left or the right side of the jaws of each subject was brushed by a dental hygienist using the manual V-shaped or the electric brush, and the other side using the manual multitufted brush. At the 2nd brushing 1 week later, the same hygienist used the multitufted brush for brushing the side contralateral to the one in which it was used the 1st week and the V-shaped manual brush instead of the electric and vice versa. After each brushing, the number of new gingival lesions was recorded and the cleansing effect evaluated by assessment of the amount of remaining plaque. This examiner was unaware of the type of brush used. The V-shaped manual toothbrush was found to have caused more gingival abrasion than the electric toothbrush (P less than 0.005) and a similar difference was found between the multitufted manual and the electric toothbrush (P less than 0.05). There was no clinically significant difference between the plaque removing effects of the 3 brushes tested. PMID:3463575

  14. Biodegradation and abrasive wear of nano restorative materials.

    PubMed

    de Paula, A B; Fucio, S B P; Ambrosano, G M B; Alonso, R C B; Sardi, J C O; Puppin-Rontani, R M

    2011-01-01

    The purpose of this study was to evaluate the biomechanical degradation of two nanofilled restorative materials (a resin-modified glass ionomer, Ketac N100 and a composite, Filtek Z350), compared with conventional materials (Vitremer and TPH Spectrum). Twenty specimens obtained from each material were divided into two storage groups (n=10): relative humidity (control) and Streptococcus mutans biofilm (biodegradation). After 7 days of storage, roughness values (Ra) and micrographs by scanning electron microscopy (SEM) were obtained. In a second experimental phase, the specimens previously subjected to biodegradation were fixed to the tooth-brushing device and abraded via toothbrushes, using dentifrice slurry (mechanical degradation). Next, these specimens were washed, dried, and reassessed by roughness and SEM. The data were submitted to repeated measures three-way analysis of variance (ANOVA) and Tukey tests (p<0.05). There was statistically significant interaction among factors: material, storage (humidity/biofilm), and abrasion (before/after). After biodegradation (S mutans biofilm storage), Ketac N100 presented the highest Ra values. Concerning bio plus mechanical challenge, TPH Spectrum, Ketac N100, and Vitremer presented the undesirable roughening of their surfaces, while the nano composite Filtek Z350 exhibited the best resistance to cumulative challenges proposed. The degraded aspect after biodegradation and the exposure of fillers after mechanical degradation were visualized in micrographs. This study demonstrated that the nanotechnology incorporated in restorative materials, as in composite resin and resin-modified glass ionomer, was important for the superior resistance to biomechanical degradation. PMID:21913859

  15. Experimental investigation of the abrasive crown dynamics in orbital atherectomy.

    PubMed

    Zheng, Yihao; Belmont, Barry; Shih, Albert J

    2016-07-01

    Orbital atherectomy is a catheter-based minimally invasive procedure to modify the plaque within atherosclerotic arteries using a diamond abrasive crown. This study was designed to investigate the crown motion and its corresponding contact force with the vessel. To this end, a transparent arterial tissue-mimicking phantom made of polyvinyl chloride was developed, a high-speed camera and image processing technique were utilized to visualize and quantitatively analyze the crown motion in the vessel phantom, and a piezoelectric dynamometer measured the forces on the phantom during the procedure. Observed under typical orbital atherectomy rotational speeds of 60,000, 90,000, and 120,000rpm in a 4.8mm caliber vessel phantom, the crown motion was a combination of high-frequency rotation at 1000, 1500, and 1660.4-1866.1Hz and low-frequency orbiting at 18, 38, and 40Hz, respectively. The measured forces were also composed of these high and low frequencies, matching well with the rotation of the eccentric crown and the associated orbital motion. The average peak force ranged from 0.1 to 0.4N at different rotational speeds. PMID:27160429

  16. Dressing of diamond grinding wheels by abrasive water jet for freeform optical surface grinding

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Yao, Peng; Li, Chengwu; Huang, Chuanzhen; Wang, Jun; Zhu, Hongtao; Liu, Zengwen

    2014-08-01

    During the ultra-precision grinding of a large aperture mirror made of RB-SiC, the grinding wheel becomes dull rapidly, which will lead to an increase of grinding force and a decrease of grinding ratio. In this paper, diamond grinding sticks were dressed with micro SiC abrasive water jet and water jet. Through single factorial experiments, the influence of jet pressure on the dressing performance was investigated. To analyze and evaluate the effect of dressing quantitatively, the 3D roughness and the wheel topography were measured and compared with laser scanning confocal microscope before and after dressing. The experimental results show that the abrasive grains are well protruded from binder and the distribution of the abrasive grains becomes uniform after dressing by abrasive water jet when the dressing parameters are properly selected. The dressing performance of abrasive water jet is much better than water jet. For dressing ultra-fine grit size wheels, the abrasive size of the jet should be smaller than the wheel grit size to achieve a better result. The jet pressure is an obvious influence factor of the surface topography.

  17. An energetic approach to abrasive wear of a martensitic stainless steel

    SciTech Connect

    Pamuk, U.; Baydogan, M.; Niluefer, B.; Cimenoglu, H.

    2000-04-01

    Abrasive wear is the most common type of wear that causes failure of machine elements. Examinations of abraded surfaces revealed presence of embedded particles and grooves elongated along the sliding direction. This indicates that, there are two sequential stages of an abrasion process. In the first stage, asperities on the hard surface and/or hard abrasive grains penetrate into the soft material surface and then in the second stage, they grind the surface in the sliding direction. Therefore, indentation and scratching of an indenter, which can be realized by hardness and scratch tests, can simulate the damage produced on the abraded surface. On the basis of this simulation, an energetic model is proposed for abrasive wear in the present study. In this study, abrasive wear behavior of a martensitic stainless steel is examined by hardness and scratch tests. The results of tests were evaluated to estimate the work done during abrasion and to find out the dimensional wear coefficient according to the model proposed above.

  18. A correlation between abrasion resistance and other properties of some acrylic resins used in dentistry.

    PubMed

    Harrison, A; Huggett, R; Handley, R W

    1979-01-01

    This investigation studies the relationship of hardness, elastic modulus and scratch width as dependent variables to the abrasion resistance of twenty-three dental acrylic resins. The multiple correlation R, when all three variables are used as predictors, is 0.727. Because of the significant intercorrelations between the variables themselves a stepwise multiple regression analysis showed hardness as a redundant variable. Abrasive wear can be estimated from the following equation Abrasive wear = 806.1 - 0.1498 modulus + 0.681 scratch width (R = 0.725; standard deviation of estimate +/- 50.8) The deletion of scratch width does not appreciably reduce the standard deviation of the estimate: Abrasive wear = 1063.4 - 0.2055 modulus (r = 0.683; standard deviation of estimate +/- 50.3) The method of curing the specimens conformed to the respective manufacturers' instructions. Abrasion and scratch tests were performed using methods developed by the authors and previously described in the literature, whereas the hardness and elastic modulus results were devised from standard test procedures. Further research is currently in progress to improve the predictive power of abrasion resistance with additional new variables. PMID:429382

  19. Two-Phase Abrasion in Eolian Transport of Gypsum Sand, White Sands NM

    NASA Astrophysics Data System (ADS)

    Shaw, S.; Jerolmack, D. J.; Miller, K. L.

    2014-12-01

    Downstream rounding of grains is consistently observed in natural sediment transport settings. A recent theory put forth by Domokos et al. (2014) attributes particle rounding and size reduction to a geometric curvature-driven abrasion process. This process occurs in two phases, in which irregularly shaped or angular particles round to convex shapes with negligible change in axis dimension, then slowly reduce in particle diameter. Miller et al (in review) establish the existence of two-phase abrasion in the natural setting of a fluvial gravel stream. This study examines field samples from White Sands, NM to investigate the presence of two-phase abrasion in a different, non-idealized natural environment - a high-energy, eolian gypsum dunefield. Analysis of grain shapes from White Sands confirms the two-phase abrasion process, dependent upon mode of sediment transport. We find that large sand grains carried in saltation bed load transport exhibit shape change indicative of two-phase abrasion, while smaller particles carried in suspension do not. We observe rapid shape change in bed load particles approaching a convex shape, followed by slower reduction in grain axis dimensions. Confirmation of this process in a natural, non-idealized setting establishes two-phase abrasion as a general application for bed load transport.

  20. Ultrafine hydrogen storage powders

    DOEpatents

    Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

    2000-06-13

    A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

  1. A versatile powder production and collection system for rapidly solidified metal and ceramic powders

    NASA Astrophysics Data System (ADS)

    Khor, K. A.

    1992-08-01

    A versatile system is described which is capable of producing fine metal and ceramic powders using three different modes of a plasma solidification process: microatomization-plasma rapid solidification using air or inert gas as the quenching medium and plasma rapid solidification using water as the quenching medium. The testing and evaluation of the system is carried out using stainless steel 316 and yttria stabilized zirconia for microatomization experiments and alumina for other plasma solidification experiments. The microatomized powders are spherical with particle sizes ranging from 0.5 to 50 microns. The productivity of the pilot-scale system is 4 kg/hr.

  2. Nanocrystalline ceria powders through citrate-nitrate combustion.

    PubMed

    Purohit, R D; Saha, S; Tyagi, A K

    2006-01-01

    Nanocrystalline ceria powders have been synthesized by combustion technique using citric acid as a fuel and nitrate as an oxidizer. The auto-ignition of the gels containing cerium nitrate and citric acid resulted in ceria powders. A theory based on adiabatic flame temperature for different citric acid-to-cerium nitrate molar ratios has been proposed to explain the nature of combustion reaction and its correlation with the powder characteristics. Specific surface area and primary particle size of the ceria powder obtained through fuel-deficient precursor was found to be approximately = 127 m2/g and 2.5-10 nm, respectively. The combustion synthesized ceria powder when cold pressed and sintered in air at 1250 degrees C for 1 hour resulted in approximately = 96% of its theoretical density with sub-micron grains. PMID:16573097

  3. Structure and properties of titanium surface layers after electron beam alloying with powder mixtures containing carbon

    NASA Astrophysics Data System (ADS)

    Lenivtseva, O. G.; Bataev, I. A.; Golkovskii, M. G.; Bataev, A. A.; Samoilenko, V. V.; Plotnikova, N. V.

    2015-11-01

    The structure and tribological properties of commercially pure titanium (cp-Ti) samples after non-vacuum electron beam surface alloying with carbon were studied. Two types of powders were used to introduce carbon in surface layer of cp-Ti: titanium carbide (TiC) and mixture of pure titanium and graphite ("Ti + C"). Single layer and multilayer coatings were studied. Application of electron beam for alloying provided cladding rate of 4.5 m2/h. The thickness of the clad coatings was 1.6-2.0 mm. The main phases received after "Ti + C" powder cladding were α-titanium, TiC, and retained graphite. In the samples obtained by cladding of TiC, graphite was not observed. A factor determining the microhardness and tribological properties of the cladded layer was the volume fraction of TiC. Maximum coating microhardness of 8 GPa was obtained by cladding of single layer of TiC powder or two layers of the "Ti + C" mixture. Two types of tests were carried out to evaluate the wear resistance of the samples. In friction tests against loose abrasive particles, the wear rate of the best samples was 9.3 times lower than that of cp-Ti. In wear tests using fixed abrasive particles, the relative wear resistance of the best samples was 2.3 times higher than that of cp-Ti.

  4. Iowa Powder Atomization Technologies

    SciTech Connect

    2012-01-01

    The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

  5. Iowa Powder Atomization Technologies

    ScienceCinema

    None

    2013-03-01

    The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

  6. The Mars Environmental Compatibility Assessment (MECA) Abrasion Tool

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Anderson, M. S.; Hinde, B. D.; Hecht, M. H.; Pike, W. T.; Marshall, J. R.; Meloy, T. P.

    1999-01-01

    The Mars Environmental Compatibility Assessment (MECA) experiment, an instrument suite to be flown on Mars Surveyor 2001, will include a tool for doing simple mineralogical scratch and streak tests on particles from the Martian regolith. The Abrasion Tool will be applied to particles that adhere themselves to highly polished substrates of various hardnesses. Granular soil components will be subjected to a compressive force of about 3 N using a leaf spring. The spring will be applied with a paraffin actuator capable of a 0.76 mm throw to achieve a maximum displacement of about 7.5 mm at the tip of the tool. The pressure per grain will be dependent on the grain size, the number of grains that adhere to the substrate and the number of grains in compression. The pressure per particle is expected to be on the order of 100 MPa - 1 GPa. The MECA sample wheel containing the substrates will be rotated after the particles are placed in compression to produce scratches or pits. A primary goal of the Abrasion Tool is to identify quartz (Mohs' hardness = 7) using substrates of varying hardnesses. Quartz is considered hazardous to future human explorers of Mars because it can cause silicosis of the lungs if it is of respirable size. It is also hazardous to machinery, structures, and space suits because of its ability to abrade and scratch surfaces. Since large quantities of minerals harder than quartz are not expected, any scratches produced on polished quartz substrates might be reasonably attributed to quartz particles, although there may be minerals such as impact metamorphic diamond in the soils. Careful calibration of the tool will be necessary to ensure that grains are not overloaded; for example, a steel ball pressed into glass will produce a Hertzian fracture, even though it is softer than glass. Other minerals, such as magnetite (Mohs' hardness = 6.5) have been shown to scratch glass ceramics such as Zerodur (Mohs' hardness = 6.5). Thus, minerals can be differentiated

  7. The Mars Environmental Compatibility Assessment MECA Abrasion Tool

    NASA Astrophysics Data System (ADS)

    Kuhlman, K. R.; Anderson, M. S.; Hinde, B. D.; Hecht, M. H.; Pike, W. T.; Marshall, J.; Meloy, T. P.; Cobbly, T.

    1999-09-01

    The Mars Environmental Compatibility Assessment (MECA) experiment, an instrument suite to be flown on Mars Surveyor 2001, will include a tool for doing simple mineralogical scratch and streak tests on particles from the Martian regolith. The Abrasion Tool will be applied to particles that adhere to highly polished substrates of various hardnesses. Granular soil components will be subjected to a compressive force of about 3 N using a leaf spring. The spring will be applied with a paraffin actuator capable of a 0.76 mm throw to achieve a maximum displacement of about 7.5 mm at the tip of the tool. The pressure per grain will be dependent on the grain size, the number of grains that adhere to the substrate and the number of grains in compression. The pressure per particle is expected to be on the order of 100 MPa - 1 GPa. The MECA sample wheel containing the substrates will be rotated after the particles are placed in compression to produce scratches or pits. A primary goal of the Abrasion Tool is to identify quartz (Mohs' hardness = 7) using substrates of varying hardnesses. Quartz is considered hazardous to future human explorers of Mars because it can cause silicosis of the lungs if it is of respirable size. It is also hazardous to machinery, structures, and space suits because of its ability to abrade and scratch surfaces. Since large quantities of minerals harder than quartz are not expected, any scratches produced on polished quartz substrates might be reasonably attributed to quartz particles, although there may be minerals such as impact metamorphic diamond in the soils. Careful calibration of the tool will be necessary to ensure that grains are not overloaded; for example, a steel ball pressed into glass will produce a Hertzian fracture, even though it is softer than glass. Other minerals, such as magnetite (Mohs'hardness = 6.5) have been shown to scratch glass ceramics such as Zerodur (Mohs' hardness = 6.5). Thus, minerals can be differentiated: note that

  8. The Mars Environmental Compatibility Assessment MECA Abrasion Tool

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Anderson, M. S.; Hinde, B. D.; Hecht, M. H.; Pike, W. T.; Marshall, J.; Meloy, T. P.; Cobbly, T.

    1999-01-01

    The Mars Environmental Compatibility Assessment (MECA) experiment, an instrument suite to be flown on Mars Surveyor 2001, will include a tool for doing simple mineralogical scratch and streak tests on particles from the Martian regolith. The Abrasion Tool will be applied to particles that adhere to highly polished substrates of various hardnesses. Granular soil components will be subjected to a compressive force of about 3 N using a leaf spring. The spring will be applied with a paraffin actuator capable of a 0.76 mm throw to achieve a maximum displacement of about 7.5 mm at the tip of the tool. The pressure per grain will be dependent on the grain size, the number of grains that adhere to the substrate and the number of grains in compression. The pressure per particle is expected to be on the order of 100 MPa - 1 GPa. The MECA sample wheel containing the substrates will be rotated after the particles are placed in compression to produce scratches or pits. A primary goal of the Abrasion Tool is to identify quartz (Mohs' hardness = 7) using substrates of varying hardnesses. Quartz is considered hazardous to future human explorers of Mars because it can cause silicosis of the lungs if it is of respirable size. It is also hazardous to machinery, structures, and space suits because of its ability to abrade and scratch surfaces. Since large quantities of minerals harder than quartz are not expected, any scratches produced on polished quartz substrates might be reasonably attributed to quartz particles, although there may be minerals such as impact metamorphic diamond in the soils. Careful calibration of the tool will be necessary to ensure that grains are not overloaded; for example, a steel ball pressed into glass will produce a Hertzian fracture, even though it is softer than glass. Other minerals, such as magnetite (Mohs'hardness = 6.5) have been shown to scratch glass ceramics such as Zerodur (Mohs' hardness = 6.5). Thus, minerals can be differentiated: note that

  9. HVOF-Sprayed Coatings Engineered from Mixtures of Nanostructured and Submicron Al2O3-TiO2 Powders: An Enhanced Wear Performance

    NASA Astrophysics Data System (ADS)

    Lima, R. S.; Moreau, C.; Marple, B. R.

    2007-12-01

    In previous studies, it has been demonstrated that nanostructured Al2O3-13 wt.%TiO2 coatings deposited via air plasma spray (APS) exhibit higher wear resistance when compared to that of conventional coatings. This study aimed to verify if high-velocity oxy-fuel (HVOF)-sprayed Al2O3-13 wt.%TiO2 coatings produced using hybrid (nano + submicron) powders could improve even further the already recognized good wear properties of the APS nanostructured coatings. According to the abrasion test results (ASTM G 64), there was an improvement in wear performance by a factor of 8 for the HVOF-sprayed hybrid coating as compared to the best performing APS conventional coating. When comparing both hybrid and conventional HVOF-sprayed coatings, there was an improvement in wear performance by a factor of 4 when using the hybrid material. The results show a significant antiwear improvement provided by the hybrid material. Scanning electron microscopy (SEM) at low/high magnifications showed the distinctive microstructure of the HVOF-sprayed hybrid coating, which helps to explain its excellent wear performance.

  10. Fluvial erosion of physically modeled abrasion-dominated slot canyons

    NASA Astrophysics Data System (ADS)

    Carter, Carissa L.; Anderson, Robert S.

    2006-11-01

    Abrasion-dominated fluvial erosion generates slot canyons in massive bedrock with intricately undulating walls. Flows in slot canyons are unusual in that the walls comprise a significant portion of the wetted perimeter of the flow during geomorphically effective floods. In Wire Pass, Utah, the upper Paria River incises through massive, crossbedded Navajo Sandstone. Incision in Wire Pass and related slots occurs only during flash floods; paleoflood debris indicates that the width/depth ratios of these flows are at times as low as 1:1. Submeter resolution field mapping of a 20-m length of Wire Pass shows that the wall morphology is a complicated combination of in-phase (meander-like) and out-of-phase (pinch and swell) undulations. In order to investigate evolution of slot canyons and the influence of their wall shapes on flow dynamics, we recorded the evolution of four distinct canyon wall morphologies in a 2.4 m flume box at the St. Anthony Falls Laboratory. In a substrate consisting of ˜ 3:2 mixtures of F110 sand and Plaster of Paris, we molded canyons with in-phase and out-of-phase undulations, and wide (6.5 cm) and narrow (4 cm) straight initial wall profiles. Discharges ranged from 1.4 L/s to 2.9 L/s, and wall and bed morphology were measured at 5 h intervals at 0.5 cm resolution. Results show efficient back-eddy erosion in the undulating canyon walls and related erosional bedforms in all channels created by vortices in the flow. Maximum filaments of velocity are depressed and asymmetric, and the implied shear stress distribution varied in space and time on the channel beds. Flow width/depth ratios strongly influence the flow structure and distribution of shear stress in a slot and appear to be a factor in dictating whether a bedrock channel widens its walls or incises its bed.

  11. Hydro- abrasive jet machining modeling for computer control and optimization

    NASA Astrophysics Data System (ADS)

    Groppetti, R.; Jovane, F.

    1993-06-01

    Use of hydro-abrasive jet machining (HAJM) for machining a wide variety of materials—metals, poly-mers, ceramics, fiber-reinforced composites, metal-matrix composites, and bonded or hybridized mate-rials—primarily for two- and three-dimensional cutting and also for drilling, turning, milling, and deburring, has been reported. However, the potential of this innovative process has not been explored fully. This article discusses process control, integration, and optimization of HAJM to establish a plat-form for the implementation of real-time adaptive control constraint (ACC), adaptive control optimiza-tion (ACO), and CAD/CAM integration. It presents the approach followed and the main results obtained during the development, implementation, automation, and integration of a HAJM cell and its computer-ized controller. After a critical analysis of the process variables and models reported in the literature to identify process variables and to define a process model suitable for HAJM real-time control and optimi-zation, to correlate process variables and parameters with machining results, and to avoid expensive and time-consuming experiments for determination of the optimal machining conditions, a process predic-tion and optimization model was identified and implemented. Then, the configuration of the HAJM cell, architecture, and multiprogramming operation of the controller in terms of monitoring, control, process result prediction, and process condition optimization were analyzed. This prediction and optimization model for selection of optimal machining conditions using multi-objective programming was analyzed. Based on the definition of an economy function and a productivity function, with suitable constraints relevant to required machining quality, required kerfing depth, and available resources, the model was applied to test cases based on experimental results.

  12. Using frictional power to model LSST removal with conventional abrasives

    NASA Astrophysics Data System (ADS)

    Allen, Richard G.; Hubler, William H.

    2015-08-01

    The stressed lap on the Large Polishing Machine (LPM) at the University of Arizona Richard F. Caris Mirror Lab has recently been used to polish the M1 and M3 surfaces of the 8.4-m mirror for the Large Synoptic Survey Telescope (LSST). Loadcells in the three 4-bar links that connect this lap to the spindle of the machine allow the translational forces and torque on the lap to be measured once a second. These force readings and all other available machine parameters are recorded in history files that can be used to create a 2D removal map from one or more polishing runs. While the Preston equation has been used for many years to predict removal in a conventional polishing process, we have adopted a new equation that assumes that removal is proportional to the energy that is transferred from the lap to the substrate via friction. Specifically, the instantaneous removal rate at any point is defined to be the product of four parameters - an energy conversion factor which we call the Allen coefficient, the coefficient of friction, the lap pressure, and the speed of the lap. The Allen coefficient is the ratio of volumetric removal to frictional energy for a particular combination of pad material, abrasive, and substrate. Because our calculations take into account changes in the coefficient of friction between the lap and mirror, our 2D removal maps usually correlate well with optical data. Removal maps for future polishing strokes are created in simulations that track the position and speed of individual lap pads.

  13. Process of high temperature synthesis in producing composite carbide powders for thermally sprayed coatings

    NASA Astrophysics Data System (ADS)

    Szymański, K.; Formanek, B.

    2011-05-01

    The paper presents the characterization of powders containing hard phases of chromium carbides in a NiCr matrix, intended for thermal spraying coatings. The synthesized composite powder containing hard phases and plastic matrix, produced in high-temperature synthesis with chosen powder metallurgy processes has been presented. Commercial materials, such as NiCr- CrxCy, are fabricated by means of agglomeration and sintering method. Processes of high temperature synthesis of Cr3C2, Cr7C3, Cr23C6 carbides combined with NiCr powder mechanical alloying are presented in the article. Parameters of the carbides synthesis were determined in the reactive -protective atmosphere. In the rotation- vibration mill, processes were conducted using grinding and appropriate mechanical alloying at variable amplitude. The standard and synthesized powders were thermally sprayed by HVOF method in Jet Kote II and Diamond Jet system. The structure and phase composition of the powders and coatings were determined by: light and scanning microscopy, X-ray phase analysis (RTG) and energy dispersive X-ray analysis (EDX). The structure and wear properties of HVOF sprayed coatings containing chromium carbides has been presented. The thermally sprayed coatings are characterized of wear resistance in abrasion and erosion tests. The sprayed coatings characterized high resistance in wear conditions.

  14. Pods: a Powder Delivery System for Mars In-situ Organic, Mineralogic and Isotopic Analysis Instruments

    NASA Technical Reports Server (NTRS)

    Saha, C. P.; Bryson, C. E.; Sarrazin, P.; Blake, D. F.

    2005-01-01

    Many Mars in situ instruments require fine-grained high-fidelity samples of rocks or soil. Included are instruments for the determination of mineralogy as well as organic and isotopic chemistry. Powder can be obtained as a primary objective of a sample collection system (e.g., by collecting powder as a surface is abraded by a rotary abrasion tool (RAT)), or as a secondary objective (e.g, by collecting drill powder as a core is drilled). In the latter case, a properly designed system could be used to monitor drilling in real time as well as to deliver powder to analytical instruments which would perform complementary analyses to those later performed on the intact core. In addition, once a core or other sample is collected, a system that could transfer intelligently collected subsamples of power from the intact core to a suite of analytical instruments would be highly desirable. We have conceptualized, developed and tested a breadboard Powder Delivery System (PoDS) intended to satisfy the collection, processing and distribution requirements of powder samples for Mars in-situ mineralogic, organic and isotopic measurement instruments.

  15. Particle-Stabilized Powdered Water-in-Oil Emulsions.

    PubMed

    Binks, Bernard P; Tyowua, Andrew T

    2016-04-01

    The preparation of powdered water-in-oil (w/o) emulsions by gentle aeration of w/o emulsions stabilized by hydrophobic fumed silica particles in the presence of oleophobic fluorinated clay particles is reported for an alkane and a triglyceride oil. The resultant powders consist of water drops dispersed in oil globules themselves dispersed in air (w/o/a). They contain ∼80 wt % of the precursor w/o emulsion and were stable to phase separation for over 1 year but release oil and water when sheared on a substrate. Above a certain ratio of w/o emulsion:fluorinated clay particles, the powdered emulsions partially invert to an emulsion paste, composed of air bubbles and water droplets dispersed in oil. The tap density and angle of repose of the powdered emulsions were measured and compared with those of the corresponding powdered oils making up the continuous phase of the precursor emulsions. The contact angles of water droplets under oil on glass slides spin coated with silica particles and oil drops and w/o emulsion droplets in air on compressed disks of fluorinated clay particles are consistent with the stabilization of w/o emulsions and powdered emulsions, respectively. PMID:27002604

  16. Demystifying Mystery Powders.

    ERIC Educational Resources Information Center

    Kotar, Michael

    1989-01-01

    Describes science activities which use simple chemical tests to distinguish between materials and to determine some of their properties. Explains the water, iodine, heat, acid, baking soda, acid/base indicator, glucose, and sugar tests. Includes activities to enhance chemical testing and a list of suggested powders for use. (RT)

  17. Novelty shop 'itching powder'.

    PubMed

    Albert, M R

    1998-08-01

    To evaluate causes of itch, commercial 'itching powders' were sought for evaluation. Only one product, produced in Germany and consisting of ground rose hips, is currently sold in novelty shops in the Boston area. These plant fibres appear to provoke itch and prickle sensations by non-allergic mechanical stimulation, similar to the action of wool fibres. PMID:9737050

  18. Combined effect of end-rounded versus tapered bristles and a dentifrice on plaque removal and gingival abrasion.

    PubMed

    Caporossi, Leonardo Stephan; Dutra, Danilo Antonio Milbradt; Martins, Maritieli Righi; Prochnow, Emilia Pithan; Moreira, Carlos Heitor Cunha; Kantorski, Karla Zanini

    2016-01-01

    Two previous clinical studies evaluated the effect of end-rounded versus tapered bristles of soft manual brushes on the removal of plaque and gingival abrasion. However, the combined effect of an abrasive dentifrice on these outcomes has yet to be understood. The purpose of the present study was to compare the incidence of gingival abrasion and the degree of plaque removal obtained after the use of toothbrushes with tapered or end-rounded bristles in the presence or absence of an abrasive dentifrice. The study involved a randomized, single-blind, crossover model (n = 39) with a split-mouth design. Subjects were instructed to refrain from performing oral hygiene procedures for 72 hours. Quadrants were randomized and subjects brushed with both types of toothbrushes using a dentifrice (relative dentin abrasion = ± 160). Plaque and gingival abrasion were assessed before and after brushing. After 7 days, the experiment was repeated without the dentifrice. The average reduction in plaque scores and the average increase in the number of abrasion sites were assessed by repeated-measures ANOVA and Bonferroni's post-hoc tests. End-rounded bristles removed significantly more plaque than tapered bristles, regardless of the use of a dentifrice. The dentifrice did not improve plaque removal. In the marginal area (cervical free gingiva), no difference in the incidence of gingival abrasion was detected between toothbrush types when used with a dentifrice (p ≥ 0.05). However, the dentifrice increased the incidence of abrasion (p < 0.001), irrespective of the toothbrush type tested. End-rounded bristles therefore removed plaque more effectively without causing a higher incidence of gingival abrasion when compared with tapered bristles. An abrasive dentifrice can increase the incidence of abrasion, and should be used with caution by individuals who are at risk of developing gingival recession. PMID:26981758

  19. Failure of a novel silicone–polyurethane copolymer (Optim™) to prevent implantable cardioverter-defibrillator lead insulation abrasions

    PubMed Central

    Hauser, Robert G.; Abdelhadi, Raed H.; McGriff, Deepa M.; Kallinen Retel, Linda

    2013-01-01

    Aim The purpose of this study was to determine if Optim™, a unique copolymer of silicone and polyurethane, protects Riata ST Optim and Durata implantable cardioverter-defibrillator (ICD) leads (SJM, St Jude Medical Inc., Sylmar, CA, USA) from abrasions that cause lead failure. Methods and results We searched the US Food and Drug Administration's (FDA's) Manufacturers and User Device Experience (MAUDE) database on 13 April 2012 using the simple search terms ‘Riata ST Optim™ abrasion analysis’ and ‘Durata abrasion analysis’. Lead implant time was estimated by subtracting 3 months from the reported lead age. The MAUDE search returned 15 reports for Riata ST Optim™ and 37 reports for Durata leads, which were submitted by SJM based on its analyses of returned leads for clinical events that occurred between December 2007 and January 2012. Riata ST Optim™ leads had been implanted 29.1 ± 11.7 months. Eight of 15 leads had can abrasions and three abrasions were caused by friction with another device, most likely another lead. Four of these abrasions resulted in high-voltage failures and one death. One failure was caused by an internal insulation defect. Durata leads had been implanted 22.2 ± 10.6 months. Twelve Durata leads had can abrasions, and six leads had abrasions caused by friction with another device. Of these 18 can and other device abrasions, 13 (72%) had electrical abnormalities. Low impedances identified three internal insulation abrasions. Conclusions Riata ST Optim™ and Durata ICD leads have failed due to insulation abrasions. Optim™ did not prevent these abrasions, which developed ≤4 years after implant. Studies are needed to determine the incidence of these failures and their clinical implications. PMID:22915789

  20. Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method

    SciTech Connect

    Han Yingchao; Li Shipu; Wang Xinyu; Chen Xiaoming

    2004-01-03

    The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 deg. C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out.

  1. The effect of heat treatment on the gouging abrasion resistance of alloy white cast irons

    NASA Astrophysics Data System (ADS)

    Are, I. R. S.; Arnold, B. K.

    1995-02-01

    A series of heat treatments was employed to vary the microstructure of four commercially important alloy white cast irons, the wear resistance of which was then assessed by the ASTM jaw-crusher gouging abrasion test. Compared with the as-cast condition, standard austenitizing treatments produced a substantial increase in hardness, a marked decrease in the retained aus-tenite content in the matrix, and, in general, a significant improvement in gouging abrasion resistance. The gouging abrasion resistance tended to decline with increasing austenitizing tem-perature, although the changes in hardness and retained austenite content varied, depending on alloy composition. Subcritical heat treatment at 500 ° following hardening reduced the retained austenite content to values less than 10 pct, and in three of the alloys it caused a significant fall in both hardness and gouging abrasion resistance. The net result of the heat treatments was the development of optimal gouging abrasion resistance at intermediate levels of retained aus-tenite. The differing responses of the alloys to both high-temperature austenitizing treatments and to subcritical heat treatments at 500 ° were related to the effects of the differing carbon and alloying-element concentrations on changes in the M s temperature and secondary carbide precipitation.

  2. Comparative Evaluation of Gingival Depigmentation using Tetrafluoroethane Cryosurgery and Gingival Abrasion Technique: Two Years Follow Up

    PubMed Central

    Kumar, Santhosh; Bhat, G. Subraya; Bhat, K. Mahalinga

    2013-01-01

    Objective: A comparative evaluation of the gingival depigmentation by using Tetrafluoroethane cryosurgery and the gingival abrasion technique – 2 years of follow up. Material and Methods: Ten systemically healthy patients who were aged 18 to 36 years were selected for the study. Tetrafluoroethane was used for the cryosurgical depigmentation and the gingival abrasion technique used a coarse flame shaped bur. The presence or absence of pigmentation was tabulated, based on the GPI (Gingival Pigmentation Index). For the statistical analysis, Freidman’s test was used. Results: The keratinization was completed within a week after the application of the cryogen and about 10 days after the gingival abrasion technique was done. The statistical analysis which was done after 90th, 180th days and 2 years. The p-value which was obtained (p<.001) showed the superiority of cryosurgery over the gingival abrasion. During the follow up period, no side effects were seen for both the techniques and the improved aesthetics was maintained upto 2 years. Conclusion: The use of cryogen Tetrafluoroethane is easy, practical and inexpensive as compared to gingival abrasion, due to its high rate of recurrence. Hence, it is more acceptable to the patients and the operator. Further studies are needed to assess the long term effectiveness of the cryosurgical method of depigmentation. PMID:23543863

  3. A novel cleaner for colloidal silica abrasive removal in post-Cu CMP cleaning

    NASA Astrophysics Data System (ADS)

    Haiwen, Deng; Baimei, Tan; Baohong, Gao; Chenwei, Wang; Zhangbing, Gu; Yan, Zhang

    2015-10-01

    A novel cleaning solution, named FA/O alkaline cleaner, was proposed and demonstrated in the removal of colloidal silica abrasives. In order to remove both the chemical and physical absorbed colloidal silica abrasives, an FA/OII chelating agent and non-ionic surfactant were added into the cleaner. By varying the concentration of chelating agent and non-ionic surfactant, a series of experiments were performed to determine the best cleaning results. This paper discusses the mechanism of the removal of colloidal silica abrasives with a FA/O alkaline cleaner. Based on the experiment results, it is concluded that both the FA/OII chelating and non-ionic surfactant could benefit the removal of colloidal silica abrasives. When the concentration of FA/OII chelating agent and FA/O non-ionic surfactant reached the optima value, it was demonstrated that silica abrasives could be removed efficiently by this novel cleaning solution. Project supported by the Specific Project Items No. 2 in National Long-Term Technology Development Plan (No. 2009zx02308-003) and the Hebei Province Department of Education Fund (No. QN2014208).

  4. Comparative evaluation of enamel abrasivity by toothbrush and velcro: An in vitro scanning electron microscope study

    PubMed Central

    Ojha, Saroj Kumar; Javdekar, Sadashiv Bhaskar; Dhir, Sangeeta

    2015-01-01

    Context: Plaque control has been shown to be pivotal in maintaining the optimal periodontal health. Mechanical plaque control is the most popular option for establishing the optimal oral health. Toothbrushes have been the novel tool for mechanical cleansing. However, the abrasive potential of the toothbrushes on the enamel surface is an area in gray. Aims: The aim of this in vitro study is to evaluate the abrasivity of the toothbrush versus the velcro fasteners. Materials and Methods: The mounted teeth of both the groups were subjected to abrasion test, and the tooth surfaces were observed for the possible abrasions from the oscillating strokes (toothbrush) and frictional contacts (hook and loop velcro) and examined under the scanning electron microscope. Results: Comparative assessment of both velcro (hook and loop) and toothbrush bristles did not reveal any evidence of abrasion on the tooth specimens. Conclusions: Veclro fasteners are safe and qualitatively at par to the manual toothbrush for their efficacy and efficiency in teeth cleansing PMID:26229264

  5. Effect of carbonitride precipitates on the abrasive wear behaviour of hardfacing alloy

    NASA Astrophysics Data System (ADS)

    Yang, Ke; Yu, Shengfu; Li, Yingbin; Li, Chenglin

    2008-06-01

    Hardfacing alloy of martensitic stainless steel expect higher abradability to be achieved through the addition of nitrogen being provided by the fine scale precipitation of complex carbonitride particles. Niobium and titanium as the most effective carbonitride alloying elements were added in the Fe-Cr13-Mn-N hardfacing alloy to get carbonitride precipitates. Carbonitride was systematically studied by optical microscopy, scanning electronic microscopy and energy spectrum analysis. Abrasive wear resistance of hardfacing alloy in as-welded and heat-treated conditions was tested by using the belt abrasion test apparatus where the samples slide against the abrasive belt. It is found that carbonitride particles in the hardfacing alloy are complex of Cr, Ti and Nb distributing on the grain boundary or matrix of the hardfacing alloy with different number and size in as-welded and heat-treated conditions. A large number of carbonitrides can be precipitated with very fine size (nanoscale) after heat treatment. As a result, the homogeneous distribution of very fine carbonitride particles can significantly improve the grain-abrasion wear-resisting property of the hardfacing alloy, and the mass loss is plastic deformation with minimum depth of grooving by abrasive particles and fine delamination.

  6. 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. PMID:17338303

  7. [Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives].

    PubMed

    Miyakawa, O; Watanabe, K; Okawa, S; Nakano, S; Shiokawa, N; Kobayashi, M; Tamura, H

    1990-01-01

    Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated. PMID:2134811

  8. The effect of erosion and abrasion on surface properties of composite resin

    NASA Astrophysics Data System (ADS)

    Stoleriu, S.; Andrian, S.; Pancu, G.; Nica, I.; Munteanu, A.; Balan, A.; Iovan, G.

    2016-06-01

    The aim of the study was to evaluate the surface roughness of two commercial composite resins submitted to erosive attack, to abrasive wear and to association of erosive and abrasive challenge. Standardized samples of G-snial anterior (GC Company) and Essentia (GC Company) composite resins were randomly split in 6 groups. In group 1 the samples were maintained in artificial saliva until the evaluation of surface roughness. In group 2 the samples were submitted only to erosive attack, in group 3 only to abrasive challenge and in groups 4,5, and 6 the erosive attack was followed by abrasive challenge immediately (group 4), 30 minutes after the erosive attack (group 5) and one hour after the erosive attack (group 6). The specimens were evaluated using surface roughness measuring tester SJ-210 (Mitutoyo Corporation, Japan) and the mean surface roughness values (Ra, μm) of each specimen were registered. A significantly increase of both composite resins surface roughness was recorded after erosive attack and abrasive challenge. Toothbrushing 60 minutes after acidic contact determined no significant differences in surface roughness of composite resins.

  9. Method to blend separator powders

    DOEpatents

    Guidotti, Ronald A.; Andazola, Arthur H.; Reinhardt, Frederick W.

    2007-12-04

    A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators.

  10. Method for synthesizing powder materials

    DOEpatents

    Buss, R.J.; Ho, P.

    1988-01-21

    A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400/degree/K (127/degree/C). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material. 1 fig.

  11. Effects of spray-drying conditions on the chemical, physical, and sensory properties of cheese powder.

    PubMed

    Koca, Nurcan; Erbay, Zafer; Kaymak-Ertekin, Figen

    2015-05-01

    Dairy powders are produced to increase the shelf life of fresh dairy products and for use as flavoring agents. In this study, 24 cheese powders produced under 7 different conditions were used to investigate the effects of spray-drying parameters (e.g., inlet air temperature, atomization pressure, and outlet air temperature) on the quality of white cheese powder. Composition, color, physical properties, reconstitution, and sensory characteristics of white cheese powders were determined. The results revealed that the white cheese powders produced in this study had low moisture content ratios and water activity values. High outlet air temperatures caused browning and enhanced Maillard reactions. Additionally, high outlet air temperatures increased wettability and dispersibility and decreased the solubility of white cheese powders. Free fat content was positively correlated with inlet air temperature and negatively correlated with outlet air temperature and atomization pressure. Sensory analyses revealed that white cheese powder samples had acceptable sensory characteristics with the exception of the sample produced at an outlet air temperature of 100°C, which had high scores for scorched flavor and color and low scores for cheese flavor. PMID:25771045

  12. Development of an Iron-Based Hardfacing Material Reinforced with Fe-(TiW)C Composite Powder

    NASA Astrophysics Data System (ADS)

    Correa, E. O.; Alcantara, N. G.; Tecco, D. G.; Kumar, R. V.

    2007-05-01

    The objective of this work is to investigate the correlation of microstructure with wear resistance in a hardfacing material reinforced with Fe-(TiW)C composite powder particles. This material was designed for cladding components subjected to highly abrasive conditions and was deposited on a low-carbon steel substrate by open arc welding. The theoretical and experimental work undertaken includes solidification study, microstructural characterization, and abrasive wear testing. Microstructural analysis of the hardfaced top layer of the alloy showed the presence of TiWC carbide particles and TiNbC carbides randomly distributed in a eutectic mixture matrix γ/M7C3 containing primary austenite dendrites. Microstructural examinations also showed that hard and fine spherulitic carbides, in which a Ti-rich MC carbide core was encircled by MC carbide enriched with Nb and W, were homogeneously distributed in the matrix. The energy-dispersive spectroscopy (EDS) mapping of spherulitic carbides showed that the any added Nb replaced a significant part of W in the Fe-(TiW)C powder, and W preferentially partitioned into other carbides and matrix during solidification. Abrasion test results showed that the preceding carbides improve the wear resistance of the hardfacing material in comparison with conventional Fe-Cr-C and Fe-Cr-C-Nb alloys, especially under high stress conditions.

  13. Processing polymeric powders

    NASA Technical Reports Server (NTRS)

    Throne, James L.

    1989-01-01

    The concept of uniformly and continuously depositing and sinter-fusing nominal 0.1 to 40 microns dimensioned electrostatically charged polymer powder particles onto essentially uniformly spread 5 to 20 micron grounded continuous fiber tow to produce a respoolable thermoplastic composite two-preg was formulated at NASA Langley. The process was reduced to practice under a NASA grant at the University of Akron this spring. The production of tow-preg is called phase 1. The production of ultrafine polymer powders from 5 to 10 percent (wt) polymer solids in solvent is considered. This is phase 0 and is discussed. The production of unitape from multi tow-pregs was also considered. This is phase 2 and is also discussed. And another approach to phase 1, also proposed last summer, was scoped. This is phase 1A and is also discussed.

  14. Advanced powder processing

    SciTech Connect

    Janney, M.A.

    1997-04-01

    Gelcasting is an advanced powder forming process. It is most commonly used to form ceramic or metal powders into complex, near-net shapes. Turbine rotors, gears, nozzles, and crucibles have been successfully gelcast in silicon nitride, alumina, nickel-based superalloy, and several steels. Gelcasting can also be used to make blanks that can be green machined to near-net shape and then high fired. Green machining has been successfully applied to both ceramic and metal gelcast blanks. Recently, the authors have used gelcasting to make tooling for metal casting applications. Most of the work has centered on H13 tool steel. They have demonstrated an ability to gelcast and sinter H13 to near net shape for metal casting tooling. Also, blanks of H13 have been cast, green machined into complex shape, and fired. Issues associated with forming, binder burnout, and sintering are addressed.

  15. Improvement in high stress abrasive wear property of steel by hardfacing

    SciTech Connect

    Kumar, S.; Mondal, D.P.; Khaira, H.K.; Jha, A.K.

    1999-12-01

    High stress abrasive wear behavior of mild steel, medium carbon steel, and hardfacing alloy has been studied to ascertain the extent of improvement in the wear properties after hardfacing of steel. High stress abrasive wear tests were carried out by sliding the specimen against the abrasive media consisting of silicon carbide particles, rigidly bonded on paper base and mounted on disk. Maximum wear was found in the case of mild steel followed by a medium carbon alloy steel and a hardfacing alloy. Different compositions of steels and constituent phases present led to different wear rates of the specimen. The extent of improvement in wear performance of steel due to hardfacing is quite appreciable (twice compared to mild steel). Microstructural examination of the wear surface has been carried out to understand the wear mechanism.

  16. Influence of material characteristics on the abrasive wear response of some hardfacing alloys

    SciTech Connect

    Jha, A.K.; Prasad, B.K.; Dasgupta, R.; Modi, O.P.

    1999-04-01

    This study examines the abrasive wear behavior of two iron-base hardfacing materials with different combinations of carbon and chromium after deposition on a steel substrate. Effects of applied load and sliding distance on the wear behavior of the specimens were studied. Operating material removal mechanisms also were analyzed through the scanning electron microscopy (SEM) examination of typical wear surfaces, subsurface regions, and debris particles. The results suggest a significant improvement in the wear resistance of the hardfaced layers over that of the substrate. Further, the specimens overlaid with the material with low carbon and high chromium contents attained better wear resistance than the one consisting of more carbon but less chromium. The former specimens also attained superior hardness. Smoother abrasion grooves on the wear surfaces and finer debris formation during the abrasion of the hardfaced samples were consistent with wear resistance superior to that of the substrate.

  17. The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

    NASA Astrophysics Data System (ADS)

    Bridges, N. T.; Calef, F. J.; Hallet, B.; Herkenhoff, K. E.; Lanza, N. L.; Le Mouélic, S.; Newman, C. E.; Blaney, D. L.; Pablo, M. A.; Kocurek, G. A.; Langevin, Y.; Lewis, K. W.; Mangold, N.; Maurice, S.; Meslin, P.-Y.; Pinet, P.; Renno, N. O.; Rice, M. S.; Richardson, M. E.; Sautter, V.; Sletten, R. S.; Wiens, R. C.; Yingst, R. A.

    2014-06-01

    Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from "Bradbury Landing" to "Rocknest," they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

  18. New vibration-assisted magnetic abrasive polishing (VAMAP) method for microstructured surface finishing.

    PubMed

    Guo, Jiang; Kum, Chun Wai; Au, Ka Hing; Tan, Zhi'En Eddie; Wu, Hu; Liu, Kui

    2016-06-13

    In order to polish microstructured surface without deteriorating its profile, we propose a new vibration-assisted magnetic abrasive polishing (VAMAP) method. In this method, magnetic force guarantees that the magnetic abrasives can well contact the microstructured surface and access the corners of microstructures while vibration produces a relative movement between microstructures and magnetic abrasives. As the vibration direction is parallel to the microstructures, the profile of the microstructures will not be deteriorated. The relation between vibration and magnetic force was analyzed and the feasibility of this method was experimentally verified. The results show that after polishing, the surface finish around microstructures was significantly improved while the profile of microstructures was well maintained. PMID:27410370

  19. Abrasion-ablation model for neutron production in heavy ion reactions

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wilson, John W.; Townsend, Lawrence W.

    1995-01-01

    In heavy ion reactions, neutron production at forward angles is observed to occur with a Gaussian shape that is centered near the beam energy and extends to energies well above that of the beam. This paper presents an abrasion-ablation model for making quantitative predictions of the neutron spectrum. To describe neutrons produced from the abrasion step of the reaction where the projectile and target overlap, the authors use the Glauber model and include effects of final-state interactions. They then use the prefragment mass distribution from abrasion with a statistical evaporation model to estimate the neutron spectrum resulting from ablation. Measurements of neutron production from Ne and Nb beams are compared with calculations, and good agreement is found.

  20. Non-abrasive particulate material for permeability alteration in subsurface formations

    SciTech Connect

    DePriester, C. L.

    1985-02-26

    An improved particulate material is disclosed for use in a method for altering the permeability of a gravity override or relatively high permeability path through a subsurface earth formation resulting from fluid injection into the subsurface formation. The method includes adding selectively sized, finely divided, amorphous non-abrasive particulate material to a fluid and injecting the fluid into the gravity override or relatively high permeability path to deposit the particulate material thus altering the permeability in the override, or relatively high permeability path. The particulate material may include graphite, carbon black, clay suspensions, quartz, or other minerals reduced in size range to behave as non-abrasive amorphous material which will present a non-abrasive characteristic in injection wells and if the particulate material is produced with formation fluids from the treated formation.

  1. Wear of artificial denture teeth by use of toothbrushes. Part 1: Abrasive wear of anterior teeth.

    PubMed

    Satoh, Y; Ohtani, K; Maejima, K; Morikawa, M; Matsuzu, M; Nagai, E; Toyoma, H; Ohwa, M; Ohki, K; Kaketani, M

    1990-12-01

    High-strength denture teeth (HS teeth) were developed in order to improve the hardness and wear resistance of conventional plastic denture teeth (PL teeth), while retaining their feature of easy occlusal adjustment. The objective of this study was to evaluate the abrasive wear resistance of HS teeth. We conducted wear tests and measured surface roughness using six types of anterior artificial teeth, i.e., three types of HS teeth and three types of PL teeth, the latter serving as the control. The results of the toothbrush abrasion test revealed that the HS teeth had about 5 times greater wear resistance than the PL teeth. It was also found that the type of artificial teeth and the number of abrasive wear-testing strokes had a significant (P less than 0.05) influence on the surface roughness of artificial teeth. PMID:2074493

  2. Abrasive wear: The efects of fibres size on oil palm empty fruit bunch polyester composite

    NASA Astrophysics Data System (ADS)

    Kasolang, S.; Kalam, A.; Ahmad, M. A.; Rahman, N. A.; Suhadah, W. N.

    2012-06-01

    This paper presents an experimental investigation carried out to determine the effect of palm oil empty fruit bunch (OPEFB) fibre size in dry sliding testing of polyester composite. These composite samples were produced by mixing raw OPEFB fibre with resin. The samples were prepared at different sizes of fibre (100, 125, 180 and 250μm). Abrasion Resistance Tester (TR-600) was used to carried out abrasive wear tests in dry sliding conditions. These tests were performed at room temperature for two different loads (10 and 30N) and at a constant sliding velocity of 1.4m/s. The specific wear rates of OPEFB polyester composites were obtained. The morphology of composite surface before and after tests was also examined using 3D microscope imaging. Preliminary work on thermal distribution at the abrasive wheel point was also conducted for selected samples.

  3. The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

    USGS Publications Warehouse

    Bridges, N.T.; Calef, F.J., III; Hallett, B.W.; Herkenhoff, Kenneth E.; Lanza, N.L.; Le Mouélic, S.; Newman, C.E.; Blaney, D.L.; de Pablo, M.A.; Kocurek, G.A.; Langevin, Y.; Lewis, K.W.; Mangold, N.; Maurice, S.; Meslin, P.-Y.; Pinet, P.; Renno, N.O.; Rice, CM.S.; Richardson, M.E.; Sautter, V.; Sletten, R.S.; Wiens, R.C.; Yingst, R.A.

    2014-01-01

    Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

  4. Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

    NASA Astrophysics Data System (ADS)

    Santos, A.; Remolina, A.; Marulanda, J.

    2016-02-01

    This project aims to compare the behaviour of an AISI 1045 steel's abrasive wear resistance when is covered with aluminium oxide (Al2O3) or Titanium dioxide (TiO2), of nanometric size, using the technique of thermal hot spray, which allows to directly project the suspension particles on the used substrate. The tests are performed based on the ASTM G65-04 standard (Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Apparatus). The results show that the amount of, lost material increases linearly with the travelled distance; also determined that the thermal treatment of hardening-tempering and the alumina and titanium dioxide coatings decrease in average a 12.9, 39.6 and 29.3% respectively the volume of released material during abrasive wear test.

  5. Photodetector Development for the Wheel Abrasion Experiment on the Sojourner Microrover of the Mars Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    Wilt, David M.; Jenkins, Phillip P.; Scheiman, David A.

    1997-01-01

    On-board the Mars Pathfinder spacecraft, launched in December of 1996, is a small roving vehicle named Sojourner. On Sojourner is an experiment to determine the abrasive characteristics of the Martian surface, called the Wheel Abrasion Experiment (WAE). The experiment works as follows: one of the wheels of the rover has a strip of black anodized aluminum bonded to the tread. The aluminum strip has thin coatings of aluminum, nickel and platinum deposited in patches. There are five (5) patches or samples of each metal, and the patches range in thickness from 200 A to 1000 A. The different metals were chosen for their differing hardness and their environmental stability. As the wheel is spun in the Martian soil, the thin patches of metal are abraded away, exposing the black anodization. The abrasion is monitored by measuring the amount of light reflected off of the samples. A photodetector was developed for this purpose, and that is the subject of this paper.

  6. Abrasion, erosion and scuffing resistance of carbide and oxide ceramic thermal sprayed coatings for different applications

    NASA Astrophysics Data System (ADS)

    Barbezat, G.; Nicoll, A. R.; Sickinger, A.

    1993-04-01

    In the area of antiwear coatings, carbide-containing coatings and oxide ceramic coatings are applied using different thermal spray processes in the form of individual layers. In many industries these coatings have become technically significant on components where wear and friction can cause critical damage in the form of abrasion, erosion and scuffing together with corrosion. Carbide-containing and ceramic coatings have been produced with different thermal spray processes for the determination of abrasive, adhesive and erosive wear resistance. Two types of abrasion test, namely an adhesion wear test and an erosion test in water at a high velocity, were used for the characterization of wear resistance under different conditions. The coatings were also characterized with regard to microstructure, composition and fracture toughness. The influence of the thermal spraying process parameters on the microstructure is presented together with the influence of the microstructure on the behavior of the coatings under simulated service conditions.

  7. Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings

    NASA Astrophysics Data System (ADS)

    Karaca, Z.; Günes Yılmaz, N.; Goktan, R. M.

    2012-01-01

    In Europe, the Wide Wheel abrasion (WWA) test and the Böhme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation ( R 2 = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly ( R 2 = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity ≥1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multi-directional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse

  8. Antioxidant components and physico-chemical characteristics of jamun powder supplemented pear juice.

    PubMed

    Kapoor, Swati; Ranote, Pushpinder Singh

    2016-05-01

    Studies were conducted to develop jamun powder supplemented pear juice. Two drying methods (Hot air cabinet drying and freeze drying) were used to prepare jamun pulp powder. Jamun powder was then blended with pear juice at 1, 2, 3, 4 and 5 % levels for preparation of jamun powder supplemented pear juice. Among the drying methods used, freeze dried powder retained better bioactive compounds and possessed higher antioxidant activity as compared to hot air dried jamun powder. Analysis of color properties (L*, a*, b*) revealed lower L*, b* values and higher a* values with progression of supplementation levels indicating decreased brightness of product. Pear juice supplemented with 4 % jamun powder received highest overall acceptability scores and was chosen for development of final product. Physico-chemical characteristics of control pear juice did not vary much from when compared to jamun powder supplemented pear juice. Bioactive components mainly total phenols enhanced (9.24 % higher) with addition of jamun powder in pear juice. Addition of anthocyanins from jamun powder to pear juice upon blending improved antioxidant activity of the final product. Supplemented pear juice had 18.13 % higher antioxidant activity than pear juice without supplementation. Storage period of 6 months resulted in significant (p < 0.05) decrease of bioactive compounds and antioxidant activity in jamun powder supplemented pear juice. PMID:27407197

  9. Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn C.

    2010-01-01

    During the Apollo program, the space suit outer layer fabrics were badly abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub -layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This Paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, and shares the results and conclusions of the testing.

  10. Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn

    2009-01-01

    During the Apollo program, the space suit outer layer fabrics were severely abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub-layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, shares the results of the testing, and provides recommendations for future work.

  11. Brushing abrasion of eroded dentin after application of sodium fluoride solutions.

    PubMed

    Attin, T; Zirkel, C; Hellwig, E

    1998-01-01

    The aim of the present in vitro study was to evaluate the influence of sodium fluoride solutions on brushing abrasion of eroded dentin. Dentin specimens were prepared from 60 bovine incisors. The specimens were embedded in acrylic resin, ground flat, polished and subsequently covered with tape exposing an area of 1.8 mm x 10.0 mm in the center of the exposed dentin. The samples were alternatingly stored in a demineralizing solution (5 min) and a remineralizing solution (1 min) for 5 times. The erosive soft drink Sprite light(R) served as a demineralizing solution and artificial saliva was used as a remineralizing solution. Prior to storage in artificial saliva 15 specimens were each treated for 1 min with 250 and 2,000 ppm fluoride solution, respectively. Fifteen specimens were treated with distilled water instead of the fluoride solution (= eroded controls). The remaining samples were neither eroded with the soft drink nor fluoridated (= uneroded controls). After each immersion in artificial saliva the specimens were submitted to abrasion in a toothbrushing machine. After 5 demineralization-remineralization brushing cycles the total amount of tooth wear due to erosion and subsequent abrasion was profilometrically evaluated. Statistical analysis revealed the significantly lowest wear in the uneroded controls and the highest amount of abrasion in the eroded controls. Application of the fluoride solutions increased the wear resistance of the eroded dentin specimens, showing significantly better protection by the high-concentration compared to the low-concentration solution. The susceptibility to abrasion of the eroded dentin specimens treated with the high-concentration fluoride solution did not differ significantly from the uneroded dentin samples. It is concluded that application of 2,000 ppm sodium fluoride solutions immediately before toothbrushing significantly reduces abrasion of eroded dentin in vitro. PMID:9701659

  12. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, Raghunath

    1998-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  13. Subsurface mechanical damage during bound abrasive grinding of fused silica glass

    NASA Astrophysics Data System (ADS)

    Blaineau, P.; André, D.; Laheurte, R.; Darnis, P.; Darbois, N.; Cahuc, O.; Neauport, J.

    2015-10-01

    The subsurface damage (SSD) introduced during bound abrasive grinding of fused silica glass was measured using a wet etch technique. Various process parameters and grinding configurations were studied. The relation between the SSD depth, the process parameters and forces applied by the grinding wheel on the sample was investigated and compared to a simulation using a discrete element method to model the grinding interface. The results reveal a relation between the SSD depth and the grinding forces normalized by the abrasive concentration. Regarding the creation of the SSD, numerical simulations indicate that only a small fraction of the largest particles in the diamond wheel are responsible for the depth of the damaged layer.

  14. Abrasion Resistance of as-Cast High-Chromium Cast Iron

    NASA Astrophysics Data System (ADS)

    Pokusová, Marcela; Berta, Igor; Šooš, Ľubomír

    2014-12-01

    High chromium cast irons are widely used as abrasion resistant materials. Their properties and wear resistance depend on carbides and on the nature of the matrix supporting these carbides. The paper presents test results of irons which contain (in wt.%) 18-22 Cr and 2-5 C, and is alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve the toughness. Tests showed as-cast irons with mostly austenitic matrix achieved hardness 36-53 HRC but their relative abrasion-resistance was higher than the tool steel STN 19436 heat treated on hardness 60 HRC.

  15. Comparison of the abrasive wear resistance between amalgams, hybrid composite material and different dental cements.

    PubMed

    Gil, F J; Espias, A; Sánchez, L A; Planell, J A

    1999-12-01

    This paper reports on the abrasion wear of various restorative dental materials (three amalgams and two dental cements and a hybrid composite material) commonly used in dentistry. The mechanical properties, surface roughness and the volume loss by abrasion were determined for the different materials studied. The results showed a better profile for the amalgams versus the composite materials due to the failure of the polymeric matrix of the latter materials. However, the amalgams exhibited corrosion observed by means of Scanning Electron Microscopy. PMID:10907431

  16. Development of pollutant release estimates due to abrasive blasting for lead paint removal from New York City Department of Transportation steel bridges

    SciTech Connect

    Lee, M.; Domanski, J.

    1999-07-01

    The use of abrasive blasting techniques in the removal of lead paint from steel bridges is a subject of public health and environmental concerns. This process creates airborne dust that must be appropriately contained to prevent inhalation or ingestion exposure during the removal activity, since some of that dust contains lead and other metals. Lead particles, if not appropriately contained, can also settle in local soils or on and within buildings, and can ultimately be inhaled or ingested. Potential worst case release scenarios for the release of dust and pollutants from paint removal operations were developed as part of the analysis framework for the Environmental Impact Statement for Lead Paint Removal Operations on New York City Department of Transportation Bridges. A multi-step analytical framework was developed for the Environmental Impact Statement (EIS), aimed at characterizing and quantifying a series of worst case scenarios for the release of contaminated material into the environment. The pollutants that the analysis focused on were lead, respirable particulates (PM10), Total Suspended Particulates (TSP) and other metals. Samples of existing paint obtained from various surfaces of representative bridges were analyzed to determine average paint dry film thickness and the concentration of metals in the paint for each of the representative bridges. Samples of expendable abrasives were analyzed to determine the concentration of metals within the abrasives. Six scenarios were developed to encompass the range of potential releases that can occur during blasting operations. Two subcategories of hypothetical release events were developed for each scenario-- reasonable worst case events and maximum worst case events. Air quality dispersion modeling with the Environmental Protection Agency's ISC3ST model was employed with the predicted release rates.

  17. Silicon nitride/silicon carbide composite powders

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-06-11

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  18. Computer Simulation of Stress-Strain State of Pipeline Section Affected by Abrasion Due to Mechanical Impurities

    NASA Astrophysics Data System (ADS)

    Burkov, P. V.; Afanas’ev, R. G.; Burkova, S. P.

    2016-04-01

    The paper presents the effect of abrasive wear of the pipeline section occurred due to mechanical impurities in the transported gas flow. The approaches to the detection of the maximum specific wear of the pipeline wall and the geometry of abrasion are the main problems of computer simulation described in this paper.

  19. Preparation of Fe-doped colloidal SiO(2) abrasives and their chemical mechanical polishing behavior on sapphire substrates.

    PubMed

    Lei, Hong; Gu, Qian; Chen, Ruling; Wang, Zhanyong

    2015-08-20

    Abrasives are one of key influencing factors on surface quality during chemical mechanical polishing (CMP). Silica sol, a widely used abrasive in CMP slurries for sapphire substrates, often causes lower material removal rate (MRRs). In the present paper, Fe-doped colloidal SiO2 composite abrasives were prepared by a seed-induced growth method in order to improve the MRR of sapphire substrates. The CMP performance of Fe-doped colloidal SiO2 abrasives on sapphire substrates was investigated using UNIPOL-1502 CMP equipment. Experimental results indicate that the Fe-doped colloidal SiO2 composite abrasives exhibit lower surface roughness and higher MRR than pure colloidal SiO2 abrasives for sapphire substrates under the same testing conditions. Furthermore, the acting mechanism of Fe-doped colloidal SiO2 composite abrasives in sapphire CMP was analyzed by x-ray photoelectron spectroscopy. Analytical results show that the Fe in the composite abrasives can react with the sapphire substrates to form aluminum ferrite (AlFeO3) during CMP, which promotes the chemical effect in CMP and leads to improvement of MRR. PMID:26368752

  20. Development of a two-body wet abrasion test method with attention to the effects of reused abradant

    SciTech Connect

    Blau, Peter Julian; Dehoff, Ryan R

    2012-01-01

    Abrasive wear is among the most common and costliest causes for material wastage, and it occurs in many forms. A simple method has been developed to quantify the response of metals and alloys to two-body wet abrasion. A metallographic polishing machine was modified to create a disk-on-flat sliding test rig. Adhesive-backed SiC grinding papers were used under fixed load and speed to rank the abrasive wear of seven alloy steels, some of which are candidates for drill cones for geothermal drilling. Standardized two-body abrasion tests, like those described in ASTM G132, feed unused abrasive into the contact; however, the current work investigated whether useful rankings could still be obtained with a simpler testing configuration in which specimens repeatedly slide on the same wear path under water-lubricated conditions. Tests using abrasive grit sizes of 120 and 180 resulted in the same relative ranking of the alloys although the coarser grit produced more total wear. Wear decreased when the same abrasive disk was re-used for up to five runs, but the relative rankings of the steels remained the same. This procedure was presented to ASTM Committee G2 on Wear and Erosion as a potential standard test for wet two-body abrasive wear.

  1. Apparatus for making environmentally stable reactive alloy powders

    DOEpatents

    Anderson, Iver E.; Lograsso, Barbara K.; Terpstra, Robert L.

    1996-12-31

    Apparatus and method for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment.

  2. Environmentally stable reactive alloy powders and method of making same

    DOEpatents

    Anderson, Iver E.; Lograsso, Barbara K.; Terpstra, Robert L.

    1998-09-22

    Apparatus and method for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment.

  3. Apparatus for making environmentally stable reactive alloy powders

    DOEpatents

    Anderson, I.E.; Lograsso, B.K.; Terpstra, R.L.

    1996-12-31

    Apparatus and method are disclosed for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment. 7 figs.

  4. Metastable nanosized aluminum powder as a reactant in energetic formulations

    SciTech Connect

    Katz, J.; Tepper, F.; Ivanov, G.V.; Lerner, M.I.; Davidovich, V.

    1998-12-01

    Aluminum powder is an important ingredient in many propellant, explosives and pyrotechnic applications. The production of nanosized aluminum powder by the electroexplosion of metal wire has been practices in the former USSR since the mid 1970`s. Differential scanning calorimetry, differential thermal analysis and x-ray phase analysis was performed on aluminum powder both before and after air passivation, as well as aluminum that was protected under kerosene, pentane, toluene and hexane. Earlier Soviet reports of unexplained thermal releases and metastable behavior have been investigated. Anomalous behavior previously reported included phase transformations at temperatures far below melting with the release of heat and chemoluminescence and self sintering of particles with a heat release large enough to melt the powders.

  5. Environmentally stable reactive alloy powders and method of making same

    DOEpatents

    Anderson, I.E.; Lograsso, B.K.; Terpstra, R.L.

    1998-09-22

    Apparatus and method are disclosed for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloys needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment. 7 figs.

  6. A critical review of non-carious cervical (wear) lesions and the role of abfraction, erosion, and abrasion.

    PubMed

    Bartlett, D W; Shah, P

    2006-04-01

    The terms 'abfraction' and 'abrasion' describe the cause of lesions found along the cervical margins of teeth. Erosion, abrasion, and attrition have all been associated with their formation. Early research suggested that the cause of the V-shaped lesion was excessive horizontal toothbrushing. Abfraction is another possible etiology and involves occlusal stress, producing cervical cracks that predispose the surface to erosion and abrasion. This article critically reviews the literature on abrasion, erosion, and abrasion, and abfraction. The references were obtained by a MEDLINE search in March, 2005, and from this, hand searches were undertaken. From the literature, there is little evidence, apart from laboratory studies, to indicate that abfraction exists other than as a hypothetical component of cervical wear. PMID:16567549

  7. Sol-gel synthesis and densification of aluminoborosilicate powders. Part 1: Synthesis

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

    1992-01-01

    Aluminoborosilicate powders high in alumina content were synthesized by the sol-gel process utilizing various methods of preparation. Properties and microstructural effects related to these syntheses were examined. After heating to 600 C for 2 h in flowing air, the powders were amorphous with the metal oxides comprising 87 percent of the weight and uncombusted organics the remainder. DTA of dried powders revealed a T(sub g) at approximately 835 C and an exotherm near 900 C due to crystallization. Powders derived from aluminum secbutoxide consisted of particles with a mean diameter 5 microns less than those from aluminum isopropoxide. Powders synthesized with aluminum isopropoxide produced agglomerates comprised of rod shaped particulates while powders made with the secbutoxide precursor produced irregular glassy shards. Compacts formed from these powders required different loadings for equivalent densities according to the method of synthesis.

  8. LARC powder prepreg system

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Marchello, Joseph M.

    1990-01-01

    Thermoplastic prepregs of LARC-TPI have been produced in a fluidized bed unit on spread continuous fiber tows. The powders are melted on the fibers by radiant heating to adhere the polymer to the fiber. This process produces tow prepreg uniformly without imposing severe stress on the fibers or requiring long high temperature residence times for the polymer. Unit design theory and operating correlations have been developed to provide the basis for scale up to commercial operation. Special features of the operation are the pneumatic tow spreader, fluidized bed and resin feed systems.

  9. A review on nozzle wear in abrasive water jet machining application

    NASA Astrophysics Data System (ADS)

    Syazwani, H.; Mebrahitom, G.; Azmir, A.

    2016-02-01

    This paper discusses a review on nozzle wear in abrasive water jet machining application. Wear of the nozzle becomes a major problem since it may affect the water jet machining performance. Design, materials, and life of the nozzle give significance effect to the nozzle wear. There are various parameters that may influence the wear rate of the nozzle such as nozzle length, nozzle inlet angle, nozzle diameter, orifice diameter, abrasive flow rate and water pressure. The wear rate of the nozzle can be minimized by controlling these parameters. The mechanism of wear in the nozzle is similar to other traditional machining processes which uses a cutting tool. The high pressure of the water and hard abrasive particles may erode the nozzle wall. A new nozzle using a tungsten carbide-based material has been developed to reduce the wear rate and improve the nozzle life. Apart from that, prevention of the nozzle wear has been achieved using porous lubricated nozzle. This paper presents a comprehensive review about the wear of abrasive water jet nozzle.

  10. Tribological properties of amorphous alloys and the role of surfaces in abrasive wear of materials

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The research approach undertaken by the authors relative to the subject, and examples of results from the authors are reviewed. The studies include programs in adhesion, friction, and various wear mechanisms (adhesive and abrasive wear). The materials which have been studied include such ceramic and metallic materials as silicon carbide, ferrites, diamond, and amorphous alloys.

  11. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  12. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  13. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  14. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  15. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Reflectorized Bicycle Wheel Rim Abrasion Test Device 8 Figure 8 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part...

  16. Optical tools for high-throughput screening of abrasion resistance of combinatorial libraries of organic coatings

    NASA Astrophysics Data System (ADS)

    Potyrailo, Radislav A.; Chisholm, Bret J.; Olson, Daniel R.; Brennan, Michael J.; Molaison, Chris A.

    2002-02-01

    Design, validation, and implementation of an optical spectroscopic system for high-throughput analysis of combinatorially developed protective organic coatings are reported. Our approach replaces labor-intensive coating evaluation steps with an automated system that rapidly analyzes 8x6 arrays of coating elements that are deposited on a plastic substrate. Each coating element of the library is 10 mm in diameter and 2 to 5 micrometers thick. Performance of coatings is evaluated with respect to their resistance to wear abrasion because this parameter is one of the primary considerations in end-use applications. Upon testing, the organic coatings undergo changes that are impossible to quantitatively predict using existing knowledge. Coatings are abraded using industry-accepted abrasion test methods at single-or multiple-abrasion conditions, followed by high- throughput analysis of abrasion-induced light scatter. The developed automated system is optimized for the analysis of diffusively scattered light that corresponds to 0 to 30% haze. System precision of 0.1 to 2.5% relative standard deviation provides capability for the reliable ranking of coatings performance. While the system was implemented for high-throughput screening of combinatorially developed organic protective coatings for automotive applications, it can be applied to a variety of other applications where materials ranking can be achieved using optical spectroscopic tools.

  17. Sand abrasion injury and plant survival in cotton seedlings of different ages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares of crops are exposed to wind-blown soil abrasion injury each year and in many instances the damage is severe enough to require replanting. Little attention has been given to plant physiological or morphological factors that may lend resistance to, or enhance recovery from, wind-...

  18. ICAM-1 mediates surface contact between neutrophils and keratocytes following corneal epithelial abrasion in the mouse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corneal epithelial abrasion elicits an inflammatory response involving neutrophil (PMN) recruitment from the limbal vessels into the corneal stroma. These migrating PMNs make surface contact with collagen and stromal keratocytes. Using mice deficient in PMN integrin CD18, we previously showed that P...

  19. NK cells modulate the inflammatory response to corneal epithelial abrasion and thereby support wound healing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural killer cells are lymphocytes of the innate immune system that have crucial cytotoxic and regulatory roles in adaptive immunity and inflammation. Herein, we consider a role for these cells in corneal wound healing. After a 2-mm central epithelial abrasion of the mouse cornea, a subset of clas...

  20. Intraoral leukoplakia, abrasion, periodontal breakdown, and tooth loss in a snuff dipper.

    PubMed

    Christen, A G; Armstrong, W R; McDaniel, R K

    1979-04-01

    Dentists should be aware that snuff dipping or chewing is increasing in southern states and perhaps in other sections of the United States. These habits can lead to clinical leukoplakia, gingival recession, tooth abrasion, and periodontal bone destruction. The possibility also exists that a malignant transformation of leukoplakia can develop in persons who use snuff and other forms of tobacco. PMID:285136

  1. Abrasive wear behavior of heat-treated ABC-silicon carbide

    SciTech Connect

    Zhang, Xiao Feng; Lee, Gun Y.; Chen, Da; Ritchie, Robert O.; De Jonghe, Lutgard C.

    2002-06-17

    Hot-pressed silicon carbide, containing aluminum, boron, and carbon additives (ABC-SiC), was subjected to three-body and two-body wear testing using diamond abrasives over a range of sizes. In general, the wear resistance of ABC-SiC, with suitable heat treatment, was superior to that of commercial SiC.

  2. Investigation of abrasion in Al–MgO metal matrix composites

    SciTech Connect

    Muharr em Pul; Çalin, Recep; Gül, Ferhat

    2014-12-15

    In this study, the effects of reinforcement volume fractions on abrasive wear behavior were examined in Al–MgO reinforced metal matrix composites of 5%, 10% and 15% reinforcement – volume ratios produced by melt-stirring. Abrasive wear tests were carried out by 60, 80 and 100 mesh sized Al{sub 2}O{sub 3} abrasive papers and pin-on-disc wear test apparatus under 10, 20 and 30 N loads at 0.2 m/s sliding speed. The mechanical properties such as hardness and fracture strength were determined. Subsequent to the wear tests, the microstructures of worn surfaces were examined by scanning electron microscope analyses. While increased MgO reinforcement volume fraction in the composite resulted increased hardness, fracture strength was determined to decrease. Additionally, it was found that increased MgO reinforcement volume fraction in the composite was accompanied with increased wear loss and porosity as well as reinforcement – volume ratio was identified to be significant determinants of abrasive wear behavior.

  3. Two waves of neutrophil emigration in response to corneal epithelial abrasion: Distinct adhesion molecule requirements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    PURPOSE: Corneal abrasion results in an inflammatory response characterized by leukocyte emigration into the corneal stroma. Adhesion molecules play a critical role in leukocyte emigration to wound sites, but differences are evident in different vascular beds. In this study, the contributions of two...

  4. Laser abrasion for cosmetic and medical treatment of facial actinic damage

    SciTech Connect

    David, L.M.; Lask, G.P.; Glassberg, E.; Jacoby, R.; Abergel, R.P.

    1989-06-01

    Previous studies have shown the carbon dioxide (CO/sub 2/) laser to be effective in the treatment of actinic cheilitis. After CO/sub 2/ laser abrasion, normal skin and marked cosmetic improvement of the lip were noted. In our study, twenty-three patients were treated with CO/sub 2/ laser abrasions for cosmetic improvement of facial lines and actinic changes. Pre- and postoperative histopathologic examinations were made on two patients. Preoperative examination of specimens from actinically damaged skin showed atypical keratinocytes in the basal layer of the epidermis, with overlying dense compact orthokeratosis and parakeratosis. Abundant solar elastosis was seen in the papillary dermis. Postoperative histologic specimens showed a normal-appearing epidermis with fibrosis in the papillary dermis and minimal solar elastosis (about four weeks after laser treatment). At present, various modalities are available for the regeneration of the aged skin, including chemical peels and dermabrasion. Significantly fewer complications were noted with CO/sub 2/ laser abrasion than with these methods. Thus, CO/sub 2/ laser abrasion can be useful in the cosmetic and medical treatment of the aged skin. Marked clinical and histologic improvement has been demonstrated.

  5. Platelet recruitment promotes keratocyte repopulation following corneal epithelial abrasion in the mouse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corneal abrasion not only damages the epithelium but also induces stromal keratocyte death at the site of injury. While a coordinated cascade of inflammatory cell recruitment facilitates epithelial restoration, it is unclear if this cascade is necessary for keratocyte recovery. Since platelet and ne...

  6. Platelet response to corneal abrasion is necessary for acute inflammation and efficient re-epithelialization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Purpose: Adhesion molecules play a critical role in leukocyte emigration to wound sites, but differences are evident in different vascular beds. This study investigates the contributions of P-selectin to neutrophil emigration into the cornea following central epithelial abrasion. Methods: Re-epithel...

  7. Martian and Terrestrial Rock Abrasion from Wind Tunnel and Field Studies

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Greeley, R.; Eddlemon, E.; Laity, J. E.; Meyer, C.; Phoreman, J.; White, B. R.

    2003-01-01

    Earth and Mars exhibit ventifacts, rocks that have been abraded by saltating sand. Previous theoretical and laboratory studies have determined abrasion susceptibilities of rocks as a function of sand type and impact angle and rock material strengths. For the last two years we have been engaged in wind tunnel and field studies to better understand the fundamental factors which control and influence rock abrasion and ventifact formation on Earth and Mars. In particular, we are examining: 1) What types of rocks (composition, texture, and shape) preferentially erode and what are the relative rates of one type vs. another? 2) What are the controlling factors of the aeolian sand cloud (flux, particle speed, surface roughness, etc) which favor rock abrasion?, 3) How do specific ventifact characteristics tie into their mode of formation and rock properties? We find several important factors: 1) Initial rock shape controls the rate of abrasion, with steeper faces abrading faster than shallower ones. The relationship is partly dependent on angle-dependent flux (proportional to sin[theta]) but exhibits additional non-linear effects from momentum transfer efficiency and rebound effects that vary with incidence angle. 2) Irregular targets with pits or grooves abrade at greater rates than targets with smooth surfaces, with indentations generally enlarging with time. Surfaces become rougher with time. 3) Targets also abrade via slope retreat, which is roughly dependent on the slope of the front face. The formation of basal sills is common, as observed on terrestrial and Martian ventifacts.

  8. Staple Line Coverage with a Polyglycolic Acid Patch and Fibrin Glue without Pleural Abrasion after Thoracoscopic Bullectomy for Primary Spontaneous Pneumothorax

    PubMed Central

    Hong, Ki Pyo; Kim, Do Kyun; Kang, Kyung Hoon

    2016-01-01

    Background This study was conducted to determine the efficacy of staple line coverage using a polyglycolic acid patch and fibrin glue without pleural abrasion to prevent recurrent postoperative pneumothorax. Methods A retrospective analysis was carried out of 116 operations performed between January 2011 and April 2013. During this period, staple lines were covered with a polyglycolic acid patch and fibrin glue in 58 cases (group A), while 58 cases underwent thoracoscopic bullectomy only (group B). Results The median follow-up period was 33 months (range, 22 to 55 months). The duration of chest tube drainage was shorter in group A (group A 2.7±1.2 day vs. group B 3.9±2.3 day, p=0.001). Prolonged postoperative air leakage occurred more frequently in group B than in group A (43% vs. 19%, p=0.005). The postoperative recurrence rate of pneumothorax was significantly lower in group A (8.6%) than in group B (24.1%) (p=0.043). The total cost of treatment during the follow-up period, including the cost for the treatment of postoperative recurrent pneumothorax, was not significantly different between the two groups (p=0.43). Conclusion Without pleural abrasion, staple line coverage with a medium-sized polyglycolic acid patch and fibrin glue after thoracoscopic bullectomy for primary spontaneous pneumothorax is a useful technique that can reduce the duration of postoperative pleural drainage and the postoperative recurrence rate of pneumothorax. PMID:27066431

  9. Forecasting of operational indicators of grinding tools with the controlled form and orientation of abrasive grains

    NASA Astrophysics Data System (ADS)

    Korotkov, V. A.; Minkin, E. M.

    2015-09-01

    The interconnection of the abrasive grain front angle parameter with the form, orientation and wear out parameters is investigated. The form of the abrasive grains was estimated by means of form coefficient which represents the relation of diameters of the spheres described around contours of grains, to diameters of the spheres entered in them. The spatial orientation angle of the abrasive grains was defined between main (i.e. the biggest) axis of the grains and the cutting plane. It is established that, depending on an orientation angle at increase in a form coefficient of the abrasive grains can be either an increase or a decrease in the values of their front angles. In most cases, with an increase in a form coefficient of the oriented grinding grains (at orientation angles Θ=10°÷125°) the growth of their front angles is fixed. At tangential orientation of grains (Θ=0°) and at the close directions of orientation (Θ=135°÷80°) the return picture is observed. Also established that the longer the abrasive grain wears along the main axis and located in the tool body, the larger is its front angle. Besides that, the front angles of the abrasive grains reach the maximum positive values at orientation angles Θ=22.5°÷45°.Dependence of tension in grains during the work with parameters of their form, orientation and depth of embedment in the bundle is investigated. It was found that for all orientation angles of grains their tension significantly increases with an increase in their form coefficient. Besides that it is confirmed that the deeper the grain is in the bundle, the lower the tension is there. Also found that tension is minimal when the grains are tangential orientated. Further on increase the option of the grains in the direction of action of the cutting force follows. Such option of orientation is the most rational both from the point of view of minimization of tension, and for ensuring rational sizes of front angles of the abrasive grains. The

  10. Gingival abrasion and recession in manual and oscillating–rotating power brush users

    PubMed Central

    Rosema, NAM; Adam, R; Grender, JM; Van der Sluijs, E; Supranoto, SC; Van der Weijden, GA

    2014-01-01

    Objective To assess gingival recession (GR) in manual and power toothbrush users and evaluate the relationship between GR and gingival abrasion scores (GA). Methods This was an observational (cross-sectional), single-centre, examiner-blind study involving a single-brushing exercise, with 181 young adult participants: 90 manual brush users and 91 oscillating–rotating power brush users. Participants were assessed for GR and GA as primary response variables. Secondary response variables were the level of gingival inflammation, plaque score reduction and brushing duration. Pearson correlation was used to describe the relationship between number of recession sites and number of abrasions. Prebrushing (baseline) and post-brushing GA and plaque scores were assessed and differences analysed using paired tests. Two-sample t-test was used to analyse group differences; ancova was used for analyses of post-brushing changes with baseline as covariate. Results Overall, 97.8% of the study population had at least one site of ≥1 mm of gingival recession. For the manual group, this percentage was 98.9%, and for the power group, this percentage was 96.7% (P = 0.621). Post-brushing, the power group showed a significantly smaller GA increase than the manual group (P = 0.004); however, there was no significant correlation between number of recession sites and number of abrasions for either group (P ≥ 0.327). Conclusions Little gingival recession was observed in either toothbrush user group; the observed GR levels were comparable. Lower post-brushing gingival abrasion levels were seen in the power group. There was no correlation between gingival abrasion as a result of brushing and the observed gingival recession following use of either toothbrush. PMID:24871587

  11. Glacial erosion and bedrock properties in NW Scotland: Abrasion and plucking, hardness and joint spacing

    NASA Astrophysics Data System (ADS)

    Krabbendam, Maarten; Glasser, Neil F.

    2011-07-01

    Subglacial erosion beneath glaciers occurs predominantly by abrasion and plucking, producing distinct erosional forms. The controls on the relative importance of abrasion vs. plucking are poorly understood. On the one hand, glacial conditions that favour or suppress cavity formation (ice velocity, ice thickness, and water pressure) are thought to favour plucking or abrasion, respectively. Conversely, bedrock properties are also known to control landforms, but this has rarely been analysed quantitatively. In this study we compare landforms and bedrock properties of sandstone and quartzite at the bed of a palaeo-ice stream near Ullapool in NW Scotland. The boundary between the rock types is at right angles to the westward palaeo-ice flow, and palaeoglacial conditions on both rock types were similar. We report quantitative parameters for bedrock properties (Schmidt hammer hardness and joint spacing) and use morphometric parameters to analyse the landforms. Torridon sandstone is soft but thick-bedded and with a wide joint spacing. Erosional bedforms include roche moutonnées with smoothed tops and concave stoss sides, whalebacks, and elongate p-forms, indicating a high proportion of abrasion over plucking. Cambrian quartzite is hard but thin-bedded with narrow joint spacing. Erosional landforms are angular to subangular with abundant plucked lee faces, suggesting a high proportion of plucking over abrasion. Hardness and joint spacing thus exert a strong control on subglacial erosional landforms and the mechanisms that formed them. Thus glacial conditions (ice velocity, ice thickness) can only be inferred from glacial erosional landforms if the effects of bedrock properties of the substrate are considered.

  12. WC-Co and Cr3C2-NiCr Coatings in Low- and High-Stress Abrasive Conditions

    NASA Astrophysics Data System (ADS)

    Kašparová, Michaela; Zahálka, František; Houdková, Šárka

    2011-03-01

    The article deals with the evaluation of abrasive wear resistance and adhesive strength of thermally sprayed coatings. The main attention was paid to differences between low- and high-stress abrasive conditions of the measuring. Conclusions include the evaluation of specific properties of the WC-Co and the Cr3C2-NiCr High Velocity Oxygen Fuel coatings and the evaluation of the changes in the behavior of the abrasive media. Mainly, the relationship between the low- and high-stress abrasion conditions and the wear mechanism in the tested materials was described. For the wear test, the abrasive media of Al2O3 and SiO2 sands were chosen. During wear tests, the volume loss of the tested materials and the surface roughness of the wear tracks were measured. The wear tracks on the tested materials and abrasive sands' morphologies were observed using Scanning Electron Microscopy. It was found that high-stress abrasive conditions change the coatings' behavior very significantly, particularly that of the Cr3C2-NiCr coating. Adhesive-cohesive properties of the coatings and relationships among individual structure particles were evaluated using tensile testing. It was found that the weak bond strength among the individual splats, structure particles, and phases plays a role in the poor wear resistance of the coatings.

  13. An abrasion-resistant and broadband antireflective silica coating by block copolymer assisted sol-gel method.

    PubMed

    Zou, Liping; Li, Xiaoguang; Zhang, Qinghua; Shen, Jun

    2014-09-01

    A double-layer broadband antireflective (AR) coating was prepared on glass substrate via sol-gel process using two kinds of acid-catalyzed TEOS-derived silica sols. The relative dense layer with a porosity of ∼10% was obtained from an as-prepared sol, while the porous layer with a porosity of ∼55% was from a modified one with block copolymer (BCP) Pluronic F127 as template which results in abundant ordered mesopores. The two layers give rise to a reasonable refractive index gradient from air to the substrate and thus high transmittance in a wide wavelength range, and both of them have the same tough skeleton despite different porosity, for which each single-layer and the double-layer coatings all behaved well in the mechanical property tests. The high transmittance and the strong ability of resisting abrasion make this coating promising for applications in some harsh conditions. In addition, the preparation is simple, low-cost, time-saving, and flexible for realizing the optical property. PMID:25117300

  14. Nanoliposomal Dry Powder Formulations

    PubMed Central

    Patel, Gaurang; Chougule, Mahavir; Singh, Mandip; Misra, Ambikanandan

    2013-01-01

    Liposomal dry powder formulations (DPFs) have proven their superiority over conventional DPFs due to favorably improved pharmacokinetics and pharmacodynamics of entrapped drugs, and thus, reduced local and systemic toxicities. Nanoliposomal DPFs (NLDPFs) provide stable, high aerosolization efficiency to deep lung, prolonged drug release, slow systemic dilution, and avoid macrophage uptake of encapsulated drug by carrier-based delivery of nano-range liposomes. This chapter describes methods of preparation of nanoliposomes (NLs) and NLDPFs, using various techniques, and their characterization with respect to size distribution, flow behavior, in vitro drug release profile, lung deposition, cellular uptake and cytotoxicity, and in vivo pharmacokinetics and pharmacodynamics. Some examples have been detailed for better understanding of the methods of preparation and evaluation of NLDPFs by investigators. PMID:19903555

  15. Comparison between PEEK and Ti6Al4V concerning micro-scale abrasion wear on dental applications.

    PubMed

    Sampaio, M; Buciumeanu, M; Henriques, B; Silva, F S; Souza, J C M; Gomes, J R

    2016-07-01

    In the oral cavity, abrasive wear is predictable at exposed tooth or restorative surfaces, during mastication and tooth brushing. Also, wear can occur at contacting surfaces between the Ti-based prosthetic structures and implants in presence of abrasive compounds from food or toothpaste. Thus, the aim of this work was to compare the abrasive wear resistance of PEEK and Ti6Al4V on three-body abrasion related to different hydrated silica content and loads. Surfaces of Ti6Al4V or PEEK cylinders (8mm diameter and 4mm height) were wet ground on SiC papers and then polished with 1µm diamond paste. After that, surfaces were ultrasonically cleaned in propyl alcohol for 15min and then in distilled water for 10min. Micro-scale abrasion tests were performed at 60rpm and on different normal loads (0.4, 0.8 or 1.2N) after 600 ball revolutions using suspensions with different weight contents of hydrated silica. After abrasive tests, wear scars on flat samples were measured to quantify the wear volume and characterized by scanning electron microscope (SEM) to identify the dominant wear mechanisms. Results showed a higher volume loss rate on PEEK than that recorded on Ti6Al4V,, when subjected to three-body abrasion tests involving hydrated silica suspensions. An increase in volume loss was noted on both tested materials when the abrasive content or load was increased. PEEK was characterized by less wear resistance than that on Ti6Al4V after micro-scale abrasion wear in contact with hydrated silica particles, as commonly found in toothpastes. PMID:26849309

  16. Validation of Proposed Metrics for Two-Body Abrasion Scratch Test Analysis Standards

    NASA Technical Reports Server (NTRS)

    Street, Kenneth W., Jr.; Kobrick, Ryan L.; Klaus, David M.

    2013-01-01

    Abrasion of mechanical components and fabrics by soil on Earth is typically minimized by the effects of atmosphere and water. Potentially abrasive particles lose sharp and pointed geometrical features through erosion. In environments where such erosion does not exist, such as the vacuum of the Moon, particles retain sharp geometries associated with fracturing of their parent particles by micrometeorite impacts. The relationship between hardness of the abrasive and that of the material being abraded is well understood, such that the abrasive ability of a material can be estimated as a function of the ratio of the hardness of the two interacting materials. Knowing the abrasive nature of an environment (abrasive)/construction material is crucial to designing durable equipment for use in such surroundings. The objective of this work was to evaluate a set of standardized metrics proposed for characterizing a surface that has been scratched from a two-body abrasion test. This is achieved by defining a new abrasion region termed Zone of Interaction (ZOI). The ZOI describes the full surface profile of all peaks and valleys, rather than just measuring a scratch width. The ZOI has been found to be at least twice the size of a standard width measurement; in some cases, considerably greater, indicating that at least half of the disturbed surface area would be neglected without this insight. The ZOI is used to calculate a more robust data set of volume measurements that can be used to computationally reconstruct a resultant profile for de tailed analysis. Documenting additional changes to various surface roughness par ameters also allows key material attributes of importance to ultimate design applications to be quantified, such as depth of penetration and final abraded surface roughness. Further - more, by investigating the use of custom scratch tips for specific needs, the usefulness of having an abrasion metric that can measure the displaced volume in this standardized

  17. Tungsten and tungsten-alloy powder metallurgy: Powder production and applications-excluding lamps. November 1971-July 1989 (Citations from the US Patent data base). Report for November 1971-July 1989

    SciTech Connect

    Not Available

    1989-10-01

    This bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys including various applications of these materials. The hydrogen reduction of tungsten compounds together with alloying-element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of various cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography. (Contains 60 citations fully indexed and including a title list.)

  18. Dissemination of Cronobacter spp. (Enterobacter sakazakii) in a Powdered Milk Protein Manufacturing Facility▿

    PubMed Central

    Mullane, N.; Healy, B.; Meade, J.; Whyte, P.; Wall, P. G.; Fanning, S.

    2008-01-01

    The microbial contamination of air filters and possible links to contaminated product in a powdered milk protein-processing facility were investigated. Over a 10-month period, seven air filters, the environment, and powdered product were analyzed for the presence of Cronobacter spp. The effects of air filter installation, maintenance, and subsequent dissemination of Cronobacter were investigated. A total of 30 isolates were characterized by pulsed-field gel electrophoresis (PFGE). PFGE revealed the presence of three clonal populations distributed throughout the manufacturing site. This study highlights the need for proper installation of air filters to limit the dissemination of microorganisms into processing sites. PMID:18641152

  19. Aerosil for the improvement of the flow behavior of powdered substances

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The tendency of powdered substances to agglomerate and stick together is studied. The highly dispersed silicic acid Aerosil (tradename) is studied as an agent to improve the free flowing characteristics of powdered materials. It was concluded that the use of Aerosil 200, Aerosil R 972, aluminum oxide C and sylicic acid D 17 as flow agents caused broad improvements in the flow properties of powders. Additionally, the sifting, dispersion, and spray behavior, as well as the grinding and air separation characteristics of powders were improved.

  20. Early abrasion of outer silicone insulation after intracardiac lead friction in a patient with cardiac device-related infective endocarditis.

    PubMed

    Ząbek, Andrej; Małecka, Barbara; Kołodzińska, Agnieszka; Maziarz, Andrej; Lelakowski, Jacek; Kutarski, Andrej

    2012-06-01

    We present a case of a 76-year-old woman on a permanent pacing device, with early abrasion of silicone endocardial lead insulations complicated by lead-dependent infective endocarditis 13 months after placement of an implantable pulse generator. The leads were removed using transvenous technique with direct traction, and with no additional tools. In the previous report, a set of additional tools was used, and therefore intraoperative endocardial lead abrasions or mechanical damage of leads could have not been excluded. The present case undoubtedly proves that the friction of leads against each other may result in abrasions of insulation of the intracardiac section of the lead. PMID:21070260

  1. Plasma Influence on Tungsten Powder

    NASA Astrophysics Data System (ADS)

    Zakharov, A.; Begrambekova, S.; Grunin, A.

    Modifications of tungsten powder comprised of micro particles with dimensions: 1 ± 0.2 μm and 5 ± 1.5 μm ("small" and «large" particles) under the influence of heating, electric field and hydrogen- and argon ion irradiation are investigated in this work. The processes in irradiated powder are described and discussed. Among them there are powder outgassing, particle emission from the powder surface in the electric field, pasting of small particles all over the large ones, integration of the adhered small particles and formation of the uniform layer around the groups of large particles, cone growth on uniform layers, formation of volumetric chains of sticking together tungsten particles and their transformations. Driving forces and processes providing different types of powder modifications and the role of each of them in the specific phenomena are discussed.

  2. Micro-abrasion-corrosion behaviour of a biomedical Ti-25Nb-3Mo-3Zr-2Sn alloy in simulated physiological fluid.

    PubMed

    Wang, Zhenguo; Li, Yan; Huang, Weijiu; Chen, Xiaoli; He, Haoran

    2016-10-01

    The micro-abrasion-corrosion behaviour of the biomedical Ti-25Nb-3Mo-3Zr-2Sn alloy in Hank׳s solution with protein has been investigated using electrochemical measurements, tribological tests and scanning electron microscope (SEM) observations. The potentiodynamic polarization tests showed that the corrosion potential (Ecorr) exhibits the maximum value at the abrasive concentration of 0.05gcm(-3) despite of the load level. The tribological results indicated that the total material loss of the Ti-25Nb-3Mo-3Zr-2Sn alloy during micro-abrasion increased with the increasing abrasive concentration at a certain applied load. When the abrasive concentration is no more than 0.15gcm(-3), the total material loss increases with increasing load, while the total material loss exhibits the maximum value at a moderate load in case of higher abrasive concentration levels. This was ascribed to the three-body or two-body micro-abrasion-corrosion at different abrasive concentration levels. The wastage map, abrasion mode map and synergy map associated with the applied load and the abrasive concentration were constructed to evaluate the micro-abrasion-corrosion behaviour of the Ti-25Nb-3Mo-3Zr-2Sn alloy in potential biomedical applications. PMID:27450038

  3. Relationship between Los Angeles attrition test and Nordic abrasion test of volcanic rocks

    NASA Astrophysics Data System (ADS)

    Krutilová, Kateřina; Prikryl, Richard

    2015-04-01

    Various volcanic rocks contribute significantly to the production of crushed stone in the Czech Republic. When used for road surfacing, results of Los Angeles attrition test (LA value below 25 or 30 depending on the mode of use) together with polished stone value are required. In the recent study, we have focused on the search for possible correlation between results obtained by Los Angeles attrition test and Nordic abrasion test, a test widely employed in Scandinavia. For the experimental study, a set of volcanic rocks from 36 active quarries was used. The rocks under study represent range of volcanic rocks from ultrabasic to acid members, formed form Neoproterozoic to Tertiary. The most favourable results of Los Angeles attrition test (i.e. the lowest LA values) were obtained for basalts (range of values 9.4-19.4) and spilites (range of values 8.4-14.9) which are in fact Neoproterozoic to Late Palaeozoic basalts affected by low grade metamorphism. Nordic abrasion test exhibited much broader range of values (6.4 to 36.9) with average value at 15.2 for basalts, resulting in weak coefficient of determination (0.19). . On contrary, narrow range of values from Nordic abrasion test of spilites (7.2-15.9), very similar to the range of LA values, is reflect in higher coefficient of determination (0.56). On contrary, the least favourable properties (LA values 12.3-29.2, Nordic abrasion 16.8-43.3) have been observed for a group of basic to intermediate rocks classified in older literature as melaphyres and diabases (ranging from basalts to trachyndesites and/or trachybasalts) of Palaeozoic age. However, in this specific group of volcanic rocks, the highest coefficient of determination (0.89) between both tests has been achieved. For volcanic rocks exhibiting acid composition (rhyolites and quartz porphyry), coefficient of determination between LA values (15.1-19.3) and Nordic abrasion test (7.3-21.9) is weak (0.42). The weakest relationship between LA values (14

  4. 70. BUILDING NO. 555, AIR DRY HOUSE FOR DOUBLE BASE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    70. BUILDING NO. 555, AIR DRY HOUSE FOR DOUBLE BASE RIFLE AND CANNON POWDERS, LOOKING NORTH AT SOUTH CORNER. FAN ROOM WITH STEAM HEATER IN FOREGROUND RIGHT. COOPER ELBOW VENTS ON ROOF ARE FROM DRYING ROOMS. STEAM LINE IN FOREGROUND, POWDER WAS DRIED ON RACKS IN DRYING ROOMS VENTILATED WITH HOT AIR. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

  5. Experimental Analysis of Spray Dryer Used in Hydroxyapatite Thermal Spray Powder

    NASA Astrophysics Data System (ADS)

    Murtaza, Q.; Stokes, J.; Ardhaoui, M.

    2012-09-01

    The spray drying process of hydroxyapatite (HA) powder used as a plasma spray powder on human hip implants was examined. The Niro-Minor mixed spray dryer was studied because it incorporates both co-current and counter-current air mixing systems. The process parameters of the spray drying were investigated: temperature, flow rate of the inlet hot air in the spray dryer, viscosity of feed/HA slurry, and responses (chamber and cyclone powder size, deposition of powder on the wall of spray dryer, and overall thermal efficiency). The statistical analysis (ANOVA test) showed that for the chamber particle size, viscosity was the most significant parameter, while for the cyclone particle size, the main effects were temperature, viscosity, and flow rate, but also their interaction effects were significant. The spray dried HA powder showed the two main shapes were a doughnut and solid sphere shape as a result of the different input.

  6. Physicochemical Properties of Microencapsulated ω-3 Salmon Oil with Egg White Powder.

    PubMed

    Mis Solval, Kevin; Bankston, J David; Bechtel, Peter J; Sathivel, Subramaniam

    2016-03-01

    The objective of this study was to produce microencapsulated omega(ω)-3 fatty acids (PUFAs) fortified egg white (EW) powders and to characterize their nutritional and physical properties. Stable emulsions (E-SO-EW) containing 3.43 (g/100 g) salmon oil (SO), 56.21 (g/100 g) EW, and 40.36 (g/100 g) water and a control (E-EW) containing EW and water were prepared. E-SO-EW and E-EW were separately spray dried at 130, 140, and 150 °C inlet air temperatures. This resulted in 3 microencapsulated SO fortified EW powders (SO-EW), and 3 dried EW powders (DEW). The powders were analyzed for microencapsulation efficiency (ME), color, fatty acids methyl esters, protein, fat, moisture, ash, amino acids, minerals, microstructure, and particle size. The EPA and DHA content of SO and the ME of the powders were not affected by the inlet air temperature. The crude protein content of SO-EW powders was approximately 24 (g/100 g) lower than dried EW powders. Leucine was the most abundant essential amino acid found in all the powders. Most of the powders' median particle size ranged from 15 to 30 μm. The study demonstrated that microencapsulated ω-3 salmon oil with high quality EW protein can be produced by spray drying. PMID:26868895

  7. Testing of Alternative Abrasives for Water-Jet Cutting at C Tank Farm

    SciTech Connect

    Krogstad, Eirik J.

    2013-08-01

    Legacy waste from defense-related activities at the Hanford Site has predominantly been stored in underground tanks, some of which have leaked; others may be at risk to do so. The U.S. Department of Energy’s goal is to empty the tanks and transform their contents into more stable waste forms. To do so requires breaking up, and creating a slurry from, solid wastes in the bottoms of the tanks. A technology developed for this purpose is the Mobile Arm Retrieval System. This system is being used at some of the older single shell tanks at C tank farm. As originally planned, access ports for the Mobile Arm Retrieval System were to be cut using a high- pressure water-jet cutter. However, water alone was found to be insufficient to allow effective cutting of the steel-reinforced tank lids, especially when cutting the steel reinforcing bar (“rebar”). The abrasive added in cutting the hole in Tank C-107 was garnet, a complex natural aluminosilicate. The hardness of garnet (Mohs hardness ranging from H 6.5 to 7.5) exceeds that of solids currently in the tanks, and was regarded to be a threat to Hanford Waste Treatment and Immobilization Plant systems. Olivine, an iron-magnesium silicate that is nearly as hard as garnet (H 6.5 to 7), has been proposed as an alternative to garnet. Pacific Northwest National Laboratory proposed to test pyrite (FeS2), whose hardness is slightly less (H 6 to 6.5) for 1) cutting effectiveness, and 2) propensity to dissolve (or disintegrate by chemical reaction) in chemical conditions similar to those of tank waste solutions. Cutting experiments were conducted using an air abrader system and a National Institute of Standards and Technology Standard Reference Material (SRM 1767 Low Alloy Steel), which was used as a surrogate for rebar. The cutting efficacy of pyrite was compared with that of garnet and olivine in identical size fractions. Garnet was found to be most effective in removing steel from the target; olivine and pyrite were less

  8. A Novel Self-Assembling Al-based Composite Powder with High Hydrogen Generation Efficiency.

    PubMed

    Wang, Cuiping; Liu, Yuheng; Liu, Hongxin; Yang, Tao; Chen, Xinren; Yang, Shuiyuan; Liu, Xingjun

    2015-01-01

    In this study, a novel self-assembling hydrogen generation powder comprised of 80Al-10Bi-10Sn wt.% was prepared using the gas atomization method and then collected in an air environment. The morphological and hydrolysis properties of the powders were investigated. The results indicated that the powders formed unique core/shell microstructures with cracked surfaces and (Bi, Sn)-rich phases distributed on the Al grain boundaries. The powders exhibited good oxidation resistance and reacted violently with distilled water at temperatures as low as 0 °C. Furthermore, at 30 °C, the powders exhibited a hydrogen conversion yield of 91.30% within 16 minutes. The hydrogen produced by this powder could be directly used in proton exchange membrane fuel cells. The mechanisms of the hydrolysis reactions were also analyzed. PMID:26616602

  9. A Novel Self-Assembling Al-based Composite Powder with High Hydrogen Generation Efficiency

    NASA Astrophysics Data System (ADS)

    Wang, Cuiping; Liu, Yuheng; Liu, Hongxin; Yang, Tao; Chen, Xinren; Yang, Shuiyuan; Liu, Xingjun

    2015-11-01

    In this study, a novel self-assembling hydrogen generation powder comprised of 80Al-10Bi-10Sn wt.% was prepared using the gas atomization method and then collected in an air environment. The morphological and hydrolysis properties of the powders were investigated. The results indicated that the powders formed unique core/shell microstructures with cracked surfaces and (Bi, Sn)-rich phases distributed on the Al grain boundaries. The powders exhibited good oxidation resistance and reacted violently with distilled water at temperatures as low as 0 °C. Furthermore, at 30 °C, the powders exhibited a hydrogen conversion yield of 91.30% within 16 minutes. The hydrogen produced by this powder could be directly used in proton exchange membrane fuel cells. The mechanisms of the hydrolysis reactions were also analyzed.

  10. A Novel Self-Assembling Al-based Composite Powder with High Hydrogen Generation Efficiency

    PubMed Central

    Wang, Cuiping; Liu, Yuheng; Liu, Hongxin; Yang, Tao; Chen, Xinren; Yang, Shuiyuan; Liu, Xingjun

    2015-01-01

    In this study, a novel self-assembling hydrogen generation powder comprised of 80Al-10Bi-10Sn wt.% was prepared using the gas atomization method and then collected in an air environment. The morphological and hydrolysis properties of the powders were investigated. The results indicated that the powders formed unique core/shell microstructures with cracked surfaces and (Bi, Sn)-rich phases distributed on the Al grain boundaries. The powders exhibited good oxidation resistance and reacted violently with distilled water at temperatures as low as 0 °C. Furthermore, at 30 °C, the powders exhibited a hydrogen conversion yield of 91.30% within 16 minutes. The hydrogen produced by this powder could be directly used in proton exchange membrane fuel cells. The mechanisms of the hydrolysis reactions were also analyzed. PMID:26616602

  11. Erosion and abrasion on dental structures undergoing at-home bleaching

    PubMed Central

    Demarco, Flávio Fernando; Meireles, Sônia Saeger; Sarmento, Hugo Ramalho; Dantas, Raquel Venâncio Fernandes; Botero, Tatiana; Tarquinio, Sandra Beatriz Chaves

    2011-01-01

    This review investigates erosion and abrasion in dental structures undergoing at- home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled. PMID:23674914

  12. M"ossbauer study of corrosion and abrasion products in oil transporting pipes

    NASA Astrophysics Data System (ADS)

    Gomez, Raul W.; Perez Mazariego, Jose Luis; Marquina, Vivianne; Marquina, Ma. Luisa; Ridaura, Rosalia; Martinez, Lorenzo

    2012-02-01

    It is known that one of the main technological problems in carbon steel oleoducts is the corrosion produced by different substances, such as water, carbon dioxide, sulfur, and microorganisms. In addition, if in such mixture there is sand, aggressive sludge can be form that abrasions material from the oleoduct. A room temperature M"ossbauer study of corroded material taken from different sites of oleoducts is presented. Most of the M"ossbauer spectra reveal the presence of nanoparticles, indicating that in these pipes the abrasion problem is severe. A preliminary identification of the oxidized samples suggests the presence of magnetite, and some Iron hydroxides. Further studies are in course in order to identify unambiguously the products present in the corroded materials.

  13. Abrasion resistance of restorative glass-ionomer cements with a light-cured surface coating.

    PubMed

    Hotta, M; Hirukawa, H

    1994-01-01

    This is a comparative study of the Knoop hardness number and the toothbrush wear of a surface coating agent applied to the surface of a glass-ionomer restorative cement. A reduction in surface hardness of the coating agent resulted in an increase in brush wear. The light-cured glazing agent (Bellfeel Brightener) proved to be significantly harder than those coated with a light-cured bonding agent (Occlusin). Occlusin bonding agent was removed by comparatively rapid abrasion; however, the Bellfeel Brightener was significantly more resistant to such abrasion. The analysis of the surface hardness and scanning electron microscopy observations of the brushed surfaces of the samples suggested that Bellfeel Brightener was effective as a glazing material for glass-ionomer cement restorations. PMID:8008609

  14. Wear of combinations of acrylic resin and porcelain, on an abrasion testing machine.

    PubMed

    Harrison, A

    1978-04-01

    Wear tests of various combinations of acrylic resin and porcelain were made using a machine which was designed to test materials under conditions similar to those of masticatory function by simulating the loads, sliding distances, and contact times encountered in the human masticatory cycle. The results showed that the amount of wear of the two materials worn in combination depended on the nature of the surrounding medium and on the surface roughness of the opposing material. Acrylic resin showed good wear resistance provided no third party abrasive or opposing hard, rough surface was present. When a mild abrasive was incorporated in the system, the acrylic resin vs acrylic resin combination wore almost seven times more than porcelain vs porcelain. Clinical experience would suggest that this is a reasonably sound order of wear. PMID:213546

  15. Abrasion resistance of titanium nitride coatings formed on titanium by ion-beam-assisted deposition.

    PubMed

    Sawase, T; Yoshida, K; Taira, Y; Kamada, K; Atsuta, M; Baba, K

    2005-02-01

    To improve the physical properties of the pure titanium surface, thin titanium nitride (TiN) films were deposited by means of ion-beam-assisted deposition. Film structure was confirmed as TiN by X-ray diffraction analysis. Surface hardness and abrasion resistance were significantly improved on TiN-coated specimens. Five combinations of oral hygiene instruments and materials were applied to the specimens as simulations of the oral environment. Treatment with the metal scaler and ultrasonic scaler severely changed the surface features and significantly increased the surface roughness parameters on pure titanium controls, whereas only small scratches and dull undulations were seen on the TiN-coated specimens. Profilometric tracings and scanning electron micrographs demonstrated the improved abrasion resistance of the TiN-coated specimens. PMID:15641983

  16. Abrasion and catastrophic rupture of lunar rocks - Some implications to the micrometeoroid flux at 1 AU.

    NASA Technical Reports Server (NTRS)

    Gault, D. E.; Hoerz, F.; Hartung, J. B.

    1972-01-01

    Results from laboratory studies of hypervelocity impact against crystalline rocks, combined with estimates of the micrometeoroid flux at the lunar surface, provide a basis for calculating abrasion rates and survival times before catastrophic rupture of rocks on the lunar surface. The surface residence times observed for lunar rocks of the order of 10 m.y. (derived from the track densities of iron group nuclei) restrict the mass range of impacting particles of interest to masses less than about 1.01 gram. Extrapolation downward to smaller masses following flux distributions suggested by early satellite data and photographic meteor observations leads to absurd rates of abrasion. Consistent with the observed crater populations on the lunar rocks and with the Pegasus, Explorer, and Pioneer satellite data, the slope of the mass-flux distribution must decrease markedly for masses below 1 to .1 microgram.

  17. Mechanisms of microhole formation on glasses by an abrasive slurry jet

    SciTech Connect

    Wang, J.; Nguyen, T.; Pang, K. L.

    2009-02-15

    Abrasive jet micromachining is considered as a promising precision processing technology for brittle materials such as silicon substrates and glasses that are increasingly used in various applications. In this paper, the mechanisms of microhole formation on brittle glasses by an abrasive slurry jet are studied based on the viscous flow and erosion theories. It is shown that the hole cross section is characterized by a ''W'' shape and can be classified into three zones caused, respectively, by jet direct impact, viscous flow, and turbulent flow induced erosion. An analysis of the surface morphology shows that ductile-mode erosion is dominant. The effect of process parameters on material removal is studied which shows that increasing the pressure and erosion time increases the hole depth, but has little effect on the hole diameter.

  18. Lip rejuvenation using chemical abrasion and padding with expanded polytetrafluoroethylene implants.

    PubMed

    Mole, B

    1996-01-01

    Aesthetic improvement of the lips is a problem that must be treated in a totally independent way from the rest of the face because degeneration of the lips is tied to genetic or acquired factors for which no long-term procedure is effective. The effectiveness of resurfacing of large and small wrinkles using chemical abrasion has long been recognized. Labial padding, using supple Gore-Tex(R) implants that are cut to size and placed where necessary provides the desired result while preserving the function of the lip. Usually requested by the younger patient, it can be used in combination with chemical abrasion in the more mature patient. This technique is not only quick, tested, very effective, and definitive, but totally reversible if needed, which allows us to widen the indications with great safety. PMID:8670390

  19. Kerf modelling in abrasive waterjet milling using evolutionary computation and ANOVA techniques

    NASA Astrophysics Data System (ADS)

    Alberdi, A.; Rivero, A.; Carrascal, A.; Lamikiz, A.

    2012-04-01

    Many researchers demonstrated the capability of Abrasive Waterjet (AWJ) technology for precision milling operations. However, the concurrence of several input parameters along with the stochastic nature of this technology leads to a complex process control, which requires a work focused in process modelling. This research work introduces a model to predict the kerf shape in AWJ slot milling in Aluminium 7075-T651 in terms of four important process parameters: the pressure, the abrasive flow rate, the stand-off distance and the traverse feed rate. A hybrid evolutionary approach was employed for kerf shape modelling. This technique allowed characterizing the profile through two parameters: the maximum cutting depth and the full width at half maximum. On the other hand, based on ANOVA and regression techniques, these two parameters were also modelled as a function of process parameters. Combination of both models resulted in an adequate strategy to predict the kerf shape for different machining conditions.

  20. Self-healing of the superhydrophobicity by ironing for the abrasion durable superhydrophobic cotton fabrics

    PubMed Central

    Wu, Jingxia; Li, Jingye; Deng, Bo; Jiang, Haiqing; Wang, Ziqiang; Yu, Ming; Li, Linfan; Xing, Chenyang; Li, Yongjin

    2013-01-01

    Self-healing of the superhydrophobic cotton fabric (SCF) obtained by the radiation-induced graft polymerization of lauryl methacrylate (LMA) and n-hexyl methacrylate (HMA), can be achieved by ironing. Through the steam ironing process, the superhydrophobicity of the SCFs will be regenerated even after the yarns are ruptured during the abrasion test under a load pressure of 44.8 kPa. SCFs made from LMA grafted cotton fabric can ultimately withstand at least 24,000 cycles of abrasion with periodic steam ironing. The FT-IR microscope results show that the migration of the polymethacrylates graft chains from the interior to the surface is responsible for the self-healing effect. PMID:24135813

  1. Development of new bound abrasive polishers for final finishing of optical glasses

    NASA Astrophysics Data System (ADS)

    Puchebner, Birgit E.; Jacobs, Stephen D.

    1995-09-01

    Because there are no practical commercially available bound abrasive polishing media, we are developing a bound abrasive polisher for deterministic finishing of optical glasses. Several in- house formulated polishing pellets, molded laps, and ring tools have been studied. Two experimental test beds were employed. The first involved the polishing of flat optical glass parts on single pellet and molded pellet laps. The tests were conducted on a single spindle machine. The performance of in-house manufactured laps was compared to experimental and commercial formulations obtained from industry. Compositions which polished the glass below 20 angstrom rms surface roughness were selected for additional testing. The second test bed for these formulations was the Opticam SM. Materials were molded into a ring tool geometry. Although the tools polished effectively, more work is required to control surface figure during final finishing.

  2. Theoretical study on removal rate and surface roughness in grinding a RB-SiC mirror with a fixed abrasive.

    PubMed

    Wang, Xu; Zhang, Xuejun

    2009-02-10

    This paper is based on a microinteraction principle of fabricating a RB-SiC material with a fixed abrasive. The influence of the depth formed on a RB-SiC workpiece by a diamond abrasive on the material removal rate and the surface roughness of an optical component are quantitatively discussed. A mathematical model of the material removal rate and the simulation results of the surface roughness are achieved. In spite of some small difference between the experimental results and the theoretical anticipation, which is predictable, the actual removal rate matches the theoretical prediction very well. The fixed abrasive technology's characteristic of easy prediction is of great significance in the optical fabrication industry, so this brand-new fixed abrasive technology has wide application possibilities. PMID:19209202

  3. Numerical Simulation Study of Influence of Nozzle Entrance Diameter on Jet Performance of Pre-mixed Abrasive Water Jet

    NASA Astrophysics Data System (ADS)

    Guan, Jinfa; Deng, Songsheng; Jiao, Guangwei; Chen, Ming; Hua, Weixing

    Physical model of cone-cylinder nozzle was established. Based on the CFD software of FLUENT, the flow field about abrasive water jet in cone-cylinder nozzle was simulated by use of standard k-ɛ turbulent model, Lagrange Discrete Phase Model and SIMPLE algorithm. The simulation results show that axial velocity of abrasive particle is always smaller than axial velocity of abrasive particle and increases gradually with the increase of axial distance. Axial static pressure of water decreases gradually with the increase of axial distance. Axial velocity of abrasive particle at the exit of cone-cylinder nozzle decreases with the increase of nozzle entrance diameter. And axial static pressure of water at the entrance of cone-cylinder nozzle decreases with the increase of nozzle entrance diameter. 8mm is selected as an optimal nozzle entrance diameter.

  4. Process for producing a well-adhered durable optical coating on an optical plastic substrate. [abrasion resistant polymethyl methacrylate lenses

    NASA Technical Reports Server (NTRS)

    Kubacki, R. M. (Inventor)

    1978-01-01

    A low temperature plasma polymerization process is described for applying an optical plastic substrate, such as a polymethyl methacrylate lens, with a single layer abrasive resistant coating to improve the durability of the plastic.

  5. Process of forming a plated wirepack with abrasive particles only in the cutting surface with a controlled kerf

    NASA Technical Reports Server (NTRS)

    Smith, Maynard B. (Inventor); Schmid, Frederick (Inventor); Khattak, Chandra P. (Inventor)

    1983-01-01

    A narrow wire blade with abrasive particles plated within a longitudinally-extending, plated cutting portion that extends from only one side of a wire core and has parallel side walls spaced by a controlled width.

  6. Two-body, dry abrasive wear of Fe/Cr/C experimental alloys - relationship between microstructure and mechanical properties

    SciTech Connect

    Kwok, C.K.S.

    1982-01-01

    A systematic study of abrasive wear resistance of Fe/Cr/Mn based alloys has been carried out using a two body pin-on-disc wear machine. Abrasives used were silicon carbide, alumina and quartz. The objective of this study was to evaluate the abrasive wear resistance and to investigate the relationships between microstructure, mechanical properties, and abrasive wear resistance for these experimental alloys. Several commercial alloys were also tested to provide a basis for comparison. The goal of this study was to develop information so as to improve wear resistance of these experimental alloys by means of thermal treatments. Grain-refinement by double heat treatment was carried out in this research.

  7. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, R.

    1998-08-04

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products. 7 figs.

  8. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, Raghunath; Blaugher, Richard D.

    1995-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  9. powder in water

    NASA Astrophysics Data System (ADS)

    Chan, Ya-Ting; Wu, Chao-Hsien; Shen, Pouyan; Chen, Shuei-Yuan

    2014-09-01

    Submicron-sized NiAl2+ X O4 fragments and nanocondensates of Ni-doped γ-Al2O3, Al-doped NiO and β-Ni(OH)2 were synthesized simultaneously by pulsed laser ablation of NiAl2O4 powder in water and characterized using X-ray/electron diffraction and optical spectroscopy. The NiAl2+ X O4 is Al-enriched spinel with dislocations and subgrains. The Ni-doped γ-Al2O3 spinel has paracrystalline distribution (i.e., with fair constant longitudinal spacing, but variable relative lateral translations) of defect clusters and intimate intergrowth of θ-Al2O3 and 2x(3) commensurate superstructure. The Al-doped NiO has perfect cubo-octahedron shape and as small as 5 nm in size. The β-Ni(OH)2 and 1-D turbostratic hydroxide lamellae occurred as a matrix of these oxide nanoparticles. The colloidal suspension containing the composite phases has a minimum band gap of 5.3 eV for potential photocatalytic applications.

  10. A statistical approach to optimize the spray drying of starch particles: application to dry powder coating.

    PubMed

    Bilancetti, Luca; Poncelet, Denis; Loisel, Catherine; Mazzitelli, Stefania; Nastruzzi, Claudio

    2010-09-01

    This article describes the preparation of starch particles, by spray drying, for possible application to a dry powder coating process. Dry powder coating consists of spraying a fine powder and a plasticizer on particles. The efficiency of the coating is linked to the powder morphological and dimensional characteristics. Different experimental parameters of the spray-drying process were analyzed, including type of solvent, starch concentration, rate of polymer feeding, pressure of the atomizing air, drying air flow, and temperature of drying air. An optimization and screening of the experimental parameters by a design of the experiment (DOE) approach have been done. Finally, the produced spray-dried starch particles were conveniently tested in a dry coating process, in comparison to the commercial initial starch. The obtained results, in terms of coating efficiency, demonstrated that the spray-dried particles led to a sharp increase of coating efficiency value. PMID:20706878

  11. Abrasive Wear Performance of Aluminium Modified Epoxy-Glass Fiber Composites

    NASA Astrophysics Data System (ADS)

    Kamble, Vikram G.; Mishra, Punyapriya; Al Dabbas, Hassan A.; Panda, H. S.; Fernandez, Johnathan Bruce

    2015-07-01

    For a long time, Aluminum filled epoxies molds have been used in rapid tooling process. These molds are very economical when applied in manufacturing of low volume of plastic parts. To improve the thermal conductivity of the material, the metallic filler material is added to it and the glass fiber improves the wear resistance of the material. These two important parameters establish the life of composites. The present work reports on abrasive wear behavior of Aluminum modified epoxy and glass fiber composite with 5 wt.% and 10 wt.% of aluminum particles. Through pin on disc wear testing machine, we studied the wear behaviors of composites, and all these samples were fabricated by using hand layup process. Epoxy resin was used as matrix material which was reinforced with Glass fiber and Aluminum as filler. The composite with 5 wt.% and 10 wt.% of Al was cast with dimensions 100 × 100 × 6 mm. The specimens were machined to a size of 6 × 6 × 4 mm for abrasive testing. Abrasive tests were carried out for different grit paper sizes, i.e., 150, 320, 600 at different sliding distance, i.e., 20, 40, 60 m at different loads of 5, 10 and 15 N and at constant speed. The weight loss due to wear was calculated along with coefficient of friction. Hardness was found using Rockwell hardness machine. The SEM morphology of the worn out surface wear was analyzed to understand the wear mechanism. Results showed that the addition of Aluminum particles was beneficial for low abrasive conditions.

  12. Abrasive Wear Resistance of Tool Steels Evaluated by the Pin-on-Disc Testing

    NASA Astrophysics Data System (ADS)

    Bressan, José Divo; Schopf, Roberto Alexandre

    2011-05-01

    Present work examines tool steels abrasion wear resistance and the abrasion mechanisms which are one main contributor to failure of tooling in metal forming industry. Tooling used in cutting and metal forming processes without lubrication fails due to this type of wear. In the workshop and engineering practice, it is common to relate wear resistance as function of material hardness only. However, there are others parameters which influences wear such as: fracture toughness, type of crystalline structure and the occurrence of hard precipitate in the metallic matrix and also its nature. In the present investigation, the wear mechanisms acting in tool steels were analyzed and, by normalized tests, wear resistance performance of nine different types of tool steels were evaluated by pin-on-disc testing. Conventional tool steels commonly used in tooling such as AISI H13 and AISI A2 were compared in relation to tool steels fabricated by sintering process such as Crucible CPM 3V, CPM 9V and M4 steels. Friction and wear testing were carried out in a pin-on-disc automated equipment which pin was tool steel and the counter-face was a abrasive disc of silicon carbide. Normal load of 5 N, sliding velocity of 0.45 m/s, total sliding distance of 3000 m and room temperature were employed. The wear rate was calculated by the Archard's equation and from the plotted graphs of pin cumulated volume loss versus sliding distance. Specimens were appropriately heat treated by quenching and three tempering cycles. Percentage of alloying elements, metallographic analyses of microstructure and Vickers microhardness of specimens were performed, analyzed and correlated with wear rate. The work is concluded by the presentation of a rank of tool steel wear rate, comparing the different tool steel abrasion wear resistance: the best tool steel wear resistance evaluated was the Crucible CPM 9V steel.

  13. Development of intermetallic-hardened abrasion-resistant weld hardfacing alloys

    SciTech Connect

    School, M.R.

    1986-01-01

    Chromium and cobalt are strategic materials in the US and both are major constituents in many weld hardfacing alloys. Substitution for these materials or alternatives to their use was a primary direction of this investigation which was conducted in conjunction with the US Bureau of Mines. Minimization of the use of strategic materials was the criteria guiding the development of intermetallic-hardened abrasion resistant weld hardfacing materials. Other criteria were that the new alloy contain a hard intermetallic compound in an FCC matrix, and that these intermetallic compounds be stable at room temperature. A survey of ternary systems was made and the Fe-Mo-Ni system was selected to provide a basis for alloy development. Fe-Mo-Ni alloys synthesized by arc-melting and similar alloys made by welding possessed similar microstructures, a (Fe, Ni){sub 7}Mo{sub 6} intermetallic plus austenite eutectic in an austenitic matrix. These materials exhibited poor abrasive resistance. Silicon additions to the alloy promoted formation of a Laves phase FeMoSi intermetallic which helped increase the abrasive wear resistance. Through a series of alloy chemistry iterations a final composition of Fe-20Mo-15Ni-5Si was selected. Heat treatment of this alloy at 550 to 650 C caused second phase precipitation in the matrix and raised the hardness about 14 points HRC to 50 HRC. The alloy's wear rate, measured with the pin-on-drum abrasive wear test, was 6.3 to 6.5 mg/m. However this was twice the wear rate observed in commercial high-carbon high-chromium alloys. Based on examination of the alloy microstructures, their chemistry, and an analysis of the Fe-Mo-Si phase system; directions for further research are to increase the molybdenum and silicon content to produce a Fe-20Mo-10Ni-15Si composition.

  14. Evaluation of weight loss and surface roughness of compomers after simulated toothbrushing abrasion test.

    PubMed

    Mondelli, Rafael Francisco Lia; Wang, Linda; Garcia, Fernanda Cristina Pimentel; Prakki, Anuradha; Mondelli, José; Franco, Eduardo Batista; Ishikiriama, Aquira

    2005-06-01

    This study aimed at analyzing the compomers wear by an "in vitro" toothbrushing abrasion test. The null hypotheses tested were that there would be no differences in weight loss and no significant changes in surface roughness of the compomers after this test. The utilized commercial brands were Dyract (Dentsply), Dyract AP (Dentsply), Compoglass F (Vivadent), Freedom (SDI), F2000 (3M ESPE), which were compared to the two resin composites Z100 (3M ESPE) and Silux Plus (3M ESPE). Ten cylindrical specimens for each commercial brand were prepared with 5mm diameter and 3mm thickness. An appropriate machine with soft bristle tips containing dentifrice solution and deionized water was used. A total of 100,000 brushing cycles were performed. The amount of weight loss was measured by the percentage alteration between the initial (before toothbrushing) and final weight (after toothbrushing), measured by a Sartorius analytical balance. The surface roughness change was determined by the percentage difference between initial and final means after 5 tracings by a T 1000 Hommel Tester roughness meter on the specimen's surfaces before and after toothbrushing abrasion test. The statistical analysis (Students paired t-test, ANOVA and Tukey, á=0.05) showed that all materials presented statistically significant weight loss and roughness increase after abrasion test. All compomers presented higher weight loss than resin composites. Freedom and Dyract AP presented the lowest weight loss among compomers. F2000 presented the worst abrasion resistance, without statistical differences with Dyract. For roughness changes, Dyract, Dyract AP, Z100, Compoglass F and Silux Plus showed the lowest surface roughness alteration, in increasing order, without statistical differences between them. Freedom was the statistically roughest material of the study. PMID:20924536

  15. Clinical in situ study investigating abrasive effects of two commercially available toothpastes.

    PubMed

    Giles, A; Claydon, N C A; Addy, M; Hughes, N; Sufi, F; West, N X

    2009-07-01

    The aim of this study was to determine if the abrasive effect on dentine of two commercially available toothpastes, known to vary in their in vitro abrasive levels, can be differentiated in an in situ model after 10 days, assessed by contact profilometry. This was a single centre, single blind, randomized, split mouth, two treatment, in situ study, in 34 healthy subjects, evaluating the abrasive effects of two marketed desensitizing toothpastes, (Colgate Sensitive Multi Protection toothpaste - C; Sensodyne Total Protection - S). Subjects wore bi-lateral, lower buccal appliances, each fitted with four dentine sections which were power brushed three times a day with the treatment regimen. Each subject received two toothpaste treatments for 10 days during the treatment period. Samples were measured at baseline and day 10 by contact and non-contact profilometry and day 5 by contact profilometry. Thirty-four subjects were included in the efficacy analysis. Results from contact profilometry showed statistically significant (P < 0.0001) dentine loss compared to baseline at day 5 and 10 for both pastes. At each time point, C showed statistically significantly greater dentine loss than S, P < 0.0001. After 10 days treatment, the difference in dentine loss between the pastes was 1.4 microm. The non-contact profilometry data showed similar trends. After 10 days of treatment, C showed statistically significantly greater dentine loss than S, with treatment difference of 0.9 microm, P = 0.0057. The methodology used has successfully differentiated between the abrasivity of the two pastes in respect of dentine surface loss over time in an in situ environment. PMID:19531090

  16. Validation of Proposed Metrics for Two-Body Abrasion Scratch Test Analysis Standards

    NASA Technical Reports Server (NTRS)

    Kobrick, Ryan L.; Klaus, David M.; Street, Kenneth W., Jr.

    2011-01-01

    The objective of this work was to evaluate a set of standardized metrics proposed for characterizing a surface that has been scratched from a two-body abrasion test. This is achieved by defining a new abrasion region termed Zone of Interaction (ZOI). The ZOI describes the full surface profile of all peaks and valleys, rather than just measuring a scratch width as currently defined by the ASTM G 171 Standard. The ZOI has been found to be at least twice the size of a standard width measurement, in some cases considerably greater, indicating that at least half of the disturbed surface area would be neglected without this insight. The ZOI is used to calculate a more robust data set of volume measurements that can be used to computationally reconstruct a resultant profile for detailed analysis. Documenting additional changes to various surface roughness parameters also allows key material attributes of importance to ultimate design applications to be quantified, such as depth of penetration and final abraded surface roughness. Data are presented to show that different combinations of scratch tips and abraded materials can actually yield the same scratch width, but result in different volume displacement or removal measurements and therefore, the ZOI method is more discriminating than the ASTM method scratch width. Furthermore, by investigating the use of custom scratch tips for our specific needs, the usefulness of having an abrasion metric that can measure the displaced volume in this standardized manner, and not just by scratch width alone, is reinforced. This benefit is made apparent when a tip creates an intricate contour having multiple peaks and valleys within a single scratch. This work lays the foundation for updating scratch measurement standards to improve modeling and characterization of three-body abrasion test results.

  17. Framework for assessing key variable dependencies in loose-abrasive grinding and polishing

    SciTech Connect

    Taylor, J.S.; Aikens, D.M.; Brown, N.J.

    1995-12-01

    This memo describes a framework for identifying all key variables that determine the figuring performance of loose-abrasive lapping and polishing machines. This framework is intended as a tool for prioritizing R&D issues, assessing the completeness of process models and experimental data, and for providing a mechanism to identify any assumptions in analytical models or experimental procedures. Future plans for preparing analytical models or performing experiments can refer to this framework in establishing the context of the work.

  18. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1996-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  19. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, M.T.; Basaran, O.A.; Kollie, T.G.; Weaver, F.J.

    1996-01-02

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm{sup 3} and an external surface area in the range of about 90 to 600 m{sup 2}/g is described. The silica powders are prepared by reacting a tetraalkyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders. 2 figs.

  20. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1995-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  1. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1994-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2 /g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  2. [Abrasion resistance of dental materials. 3. Surface quality study of Evicrol by wear measurements at different layer depths].

    PubMed

    Tappe, A; Eichhorn, T

    1980-04-01

    Abrasion determinations in various layer depths showed that the layer of the filling material Evicrol directly under the matrix-hardened surface is more abrasion-resistant than the matrix- hardened surface. From this it is concluded that it is good practice to overfill in making restorations of Evicrol and to remove a certain layer of material (approximately 0.25 mm, according to Fraunhofer). PMID:6935842

  3. Defining an Abrasion Index for Lunar Surface Systems as a Function of Dust Interaction Modes and Variable Concentration Zones

    NASA Technical Reports Server (NTRS)

    Kobrick, Ryan L.; Klaus, David M.; Street, Kenneth W., Jr.

    2010-01-01

    Unexpected issues were encountered during the Apollo era of lunar exploration due to detrimental abrasion of materials upon exposure to the fine-grained, irregular shaped dust on the surface of the Moon. For critical design features involving contact with the lunar surface and for astronaut safety concerns, operational concepts and dust tolerance must be considered in the early phases of mission planning. To systematically define material selection criteria, dust interaction can be characterized by two-body or three-body abrasion testing, and subcategorically by physical interactions of compression, rolling, sliding and bending representing specific applications within the system. Two-body abrasion occurs when a single particle or asperity slides across a given surface removing or displacing material. Three-body abrasion occurs when multiple particles interact with a solid surface, or in between two surfaces, allowing the abrasives to freely rotate and interact with the material(s), leading to removal or displacement of mass. Different modes of interaction are described in this paper along with corresponding types of tests that can be utilized to evaluate each configuration. In addition to differential modes of abrasion, variable concentrations of dust in different zones can also be considered for a given system design and operational protocol. These zones include: (1) outside the habitat where extensive dust exposure occurs, (2) in a transitional zone such as an airlock or suitport, and (3) inside the habitat or spacesuit with a low particle count. These zones can be used to help define dust interaction frequencies, and corresponding risks to the systems and/or crew can be addressed by appropriate mitigation strategies. An abrasion index is introduced that includes the level of risk, R, the hardness of the mineralogy, H, the severity of the abrasion mode, S, and the frequency of particle interactions, F.

  4. Defining an abrasion index for lunar surface systems as a function of dust interaction modes and variable concentration zones

    NASA Astrophysics Data System (ADS)

    Kobrick, Ryan L.; Klaus, David M.; Street, Kenneth W.

    2011-11-01

    Unexpected issues were encountered during the Apollo era of lunar exploration due to detrimental abrasion of materials upon exposure to the fine-grained, irregular shaped dust on the surface of the Moon. For critical design features involving contact with the lunar surface and for astronaut safety concerns, operational concepts and dust tolerance must be considered in the early phases of mission planning. To systematically define material selection criteria, dust interaction can be characterized by two-body or three-body abrasion testing, and sub-categorically by physical interactions of compression, rolling, sliding, and bending representing specific applications within the system. Two-body abrasion occurs when a single particle or asperity slides across a given surface removing or displacing material. Three-body abrasion occurs when multiple particles interact with a solid surface, or in between two surfaces, allowing the abrasives to freely rotate and interact with the material(s), leading to removal or displacement of mass. Different modes of interaction are described in this paper along with corresponding types of tests that can be utilized to evaluate each configuration. In addition to differential modes of abrasion, variable concentrations of dust in different zones can also be considered for a given system design and operational protocol. These zones include (1) outside the habitat where extensive dust exposure occurs, (2) in a transitional zone such as an airlock or suitport, and (3) inside the habitat or spacesuit with a low particle count. These zones can be used to help define dust interaction frequencies, and corresponding risks to the systems and/or crew can be addressed by appropriate mitigation strategies. An abrasion index is introduced that includes the level of risk, R, the hardness of the mineralogy, H, the severity of the abrasion mode, S, and the frequency of particle interactions, F.

  5. Method for molding ceramic powders

    DOEpatents

    Janney, M.A.

    1990-01-16

    A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, where after the product may be sintered.

  6. Method for molding ceramic powders

    DOEpatents

    Janney, Mark A.

    1990-01-01

    A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

  7. Shock compaction of molybdenum powder

    NASA Technical Reports Server (NTRS)

    Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.

    1983-01-01

    Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.

  8. Evaluation of planarization performance for a novel alkaline copper slurry under a low abrasive concentration

    NASA Astrophysics Data System (ADS)

    Mengting, Jiang; Yuling, Liu; Haobo, Yuan; Guodong, Chen; Weijuan, Liu

    2014-11-01

    A novel alkaline copper slurry that possesses a relatively high planarization performance is investigated under a low abrasive concentration. Based on the action mechanism of CMP, the feasibility of using one type of slurry in copper bulk elimination process and residual copper elimination process, with different process parameters, was analyzed. In addition, we investigated the regular change of abrasive concentration effect on copper and tantalum removal rate and within wafer non-uniformity (WIWNU) in CMP process. When the abrasive concentration is 3 wt%, in bulk elimination process, the copper removal rate achieves 6125 Å/min, while WIWNU is 3.5%, simultaneously. In residual copper elimination process, the copper removal rate is approximately 2700 Å/min, while WIWNU is 2.8%. Nevertheless, the tantalum removal rate is 0 Å/min, which indicates that barrier layer isn't eliminated in residual copper elimination process. The planarization experimental results show that an excellent planarization performance is obtained with a relatively high copper removal rate in bulk elimination process. Meanwhile, after residual copper elimination process, the dishing value increased inconspicuously, in a controllable range, and the wafer surface roughness is only 0.326 nm (sq < 1 nm) after polishing. By comparison, the planarization performance and surface quality of alkaline slurry show almost no major differences with two kinds of commercial acid slurries after polishing. All experimental results are conducive to research and improvement of alkaline slurry in the future.

  9. Effect of abrasive surface roughening on the secondary yield of various metals

    NASA Astrophysics Data System (ADS)

    Graves, Timothy

    2007-11-01

    The secondary electron yield of metallic conductors plays a critical role in the development of multipactor discharges. These discharges require a secondary yield greater than unity at the appropriate energy level for sustained breakdown. By reducing the secondary yield below unity in the necessary energy range, multipactor and multipactor-induced glow discharges can be eliminated. Surface roughening has been shown to successfully lower the secondary yield to below unity (ref. 1). In addition, abrasive bead blasting has been shown to effectively reduce the secondary yield of copper surfaces while preserving voltage breakdown characteristics (ref. 2). This study investigates the effect of abrasive surface roughening on the secondary yield of materials such as copper, aluminum, and stainless steel. In addition to measuring the change in the secondary yield as a function of abrasive particle size, the multipactor resistance and voltage breakdown characteristics are investigated. In addition, the effect of vacuum conditioning via multipactor and rf plasma cleaning on the roughened surfaces will be discussed. Ref. 1. H. Bruining. Physics and Applications of Secondary Electron Emission. McGraw-Hill, NY, 1954. Ref. 2. T. P. Graves, Ph.D. Thesis, MIT. 2007

  10. Development and Testing of Abrasion Resistant Hard Coats For Polymer Film Reflectors: Preprint

    SciTech Connect

    Jorgensen, G.; Gee, R.; DiGrazia, M.

    2010-10-01

    Reflective polymer film technology can significantly reduce the cost of solar reflectors and installed Concentrated Solar Power (CSP) plants by both reduced material cost and lower weight. One challenge of polymer reflectors in the CSP environment pertains to contact cleaning methods typically used with glass mirrors. Such contact cleaning methods can scratch the surface of polymer reflectors and thereby reduce specular reflectance. ReflecTech, Inc. (a subsidiary of SkyFuel, Inc.) and the National Renewable Energy Laboratory (NREL) initiated a cooperative research and development agreement (CRADA) to devise and develop an abrasion resistant coating (ARC) suitable for deposition onto polymer based mirror film. A number of candidate ARC products were identified as candidate formulations. Industrial collaborators prepared samples having their ARCs deposited onto ReflecTech Mirror Film pre-laminated to aluminum sheet substrates. Samples were provided for evaluation and subjected to baseline (unweathered) and accelerated exposure conditions and subsequently characterized for abrasion resistance and adhesion. An advanced ARC product has been identified that exhibits outstanding initial abrasion resistance and adhesion to ReflecTech Mirror Film. These properties were also retained after exposure to the various accelerated stress conditions. This material has been successfully manufactured as a 1.5 m wide roll-to-roll construction in a production environment.

  11. Study on ultra-precision magnetic abrasive finishing process using low frequency alternating magnetic field

    NASA Astrophysics Data System (ADS)

    Wu, Jinzhong; Zou, Yanhua; Sugiyama, Hitoshi

    2015-07-01

    We proposed a new ultra-precision magnetic abrasive finishing (MAF) process using low frequency alternating magnetic field in this paper. Magnetic cluster themselves may produce the up and down movement change under alternating magnetic force. The movement may not only promote the dispersion of micro-magnetic particles, but also improve stirring effect and cross-cutting effects of the abrasives, achieving circulation and update to ensure the stability of grinding tools. This process is considered to be able to efficiently apply in ultra-precision finishing of plane and complicated micro-surfaces. In this study, we investigated the effects of alternating magnetic field on magnetic field distribution, finishing force and abrasive behavior. Furthermore, a set of experimental devices have been designed for finishing SUS304 stainless steel plate. The present work is aimed at understanding finishing particularity of this process and studying impacts of important process parameters namely grinding fluid, rotational speed of magnetic pole, current frequency on change in finish surface and material removal. Experimental results indicate that the process can realize ultra-precision finishing of plane by using oily grinding fluid. In the present research, the surface roughness of SUS304 stainless steel plate was improved from 240.24 nm to 4.38 nm by this process.

  12. Rock Cutting Depth Model Based on Kinetic Energy of Abrasive Waterjet

    NASA Astrophysics Data System (ADS)

    Oh, Tae-Min; Cho, Gye-Chun

    2016-03-01

    Abrasive waterjets are widely used in the fields of civil and mechanical engineering for cutting a great variety of hard materials including rocks, metals, and other materials. Cutting depth is an important index to estimate operating time and cost, but it is very difficult to predict because there are a number of influential variables (e.g., energy, geometry, material, and nozzle system parameters). In this study, the cutting depth is correlated to the maximum kinetic energy expressed in terms of energy (i.e., water pressure, water flow rate, abrasive feed rate, and traverse speed), geometry (i.e., standoff distance), material (i.e., α and β), and nozzle system parameters (i.e., nozzle size, shape, and jet diffusion level). The maximum kinetic energy cutting depth model is verified with experimental test data that are obtained using one type of hard granite specimen for various parameters. The results show a unique curve for a specific rock type in a power function between cutting depth and maximum kinetic energy. The cutting depth model developed here can be very useful for estimating the process time when cutting rock using an abrasive waterjet.

  13. An abrasion-ablation model description of galactic heavy-ion fragmentation

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.; Norbury, J. W.; Bidasaria, H. B.

    1984-01-01

    The fragmentation of high-energy galactic heavy ions by nuclear interactions with arbitrary target nuclei is described within the context of a simple abrasion-ablation fragmentation model. The abrasion part of the theory utilizes a quantum-mechanical formalism based upon an optical model potential approximation to the exact nucleus-nucleus multiple-scattering series. Nuclear charge distributions of the excited prefragments are calculated using either a hypergeometric distribution or a method based upon the zero-point oscillations of the giant dipole resonance. The excitation energy of the prefragment is estimated from the geometric clean-cut abrasion-ablation model. The decay probabilities for the various particle emission channels, in the ablation stage of the fragmentation, are obtained from the EVAP-4 Monte Carlo computer program. Elemental production cross sections for 1.88-GeV/nucleon iron colliding with carbon, silver, and lead targets are calculated and compared with experimental data and with the predictions from the semiempirical relations of Silberberg and Tsao.

  14. The surface quality of AWJ cut parts as a function of abrasive material reusing rate

    NASA Astrophysics Data System (ADS)

    Schnakovszky, C.; Herghelegiu, E.; Radu, M. C.; Tampu, N. C.

    2015-11-01

    Abrasive water jet cutting (AWJ) has been extensively used during the last years to process a large variety of materials since it offers important advantages as a good quality of the processed surface, without heat affected zones, low environmental impact (no emission of dust or other compounds that endanger the health of the user), small induced mechanical stresses etc. The main disadvantage is the high cost of processing (cost of equipment and consumables). In view of this, the effects of reusing the abrasive material on the quality of processed surface are investigated in this paper. Two steel materials were used: OL 37 (S 235) with large applicability in machine building industry and 2P armor steel used in the arms industry. The reusing rate of the garnet abrasive material was: 0%, 20%, 40%, 60%, 80% and 100%. The quality of processed surface was quantified by the following parameters: width at the jet inlet (Li), width at the jet outlet (Lo), inclination angle (α), deviation from perpendicularity (u) and roughness (Ra).

  15. Tooth length and incisal wear and growth in guinea pigs (Cavia porcellus) fed diets of different abrasiveness.

    PubMed

    Müller, J; Clauss, M; Codron, D; Schulz, E; Hummel, J; Kircher, P; Hatt, J-M

    2015-06-01

    Dental diseases are among the most important reasons for presenting guinea pigs (Cavia porcellus) and other rodents to veterinary clinics, but the aetiopathology of this disease complex is unclear. Clinicians tend to believe that the ever-growing teeth of rabbits and rodents have a constant growth that needs to be worn down by the mastication of an appropriate diet. In this study, we tested the effect of four different pelleted diets of increasing abrasiveness [due to both internal (phytoliths) and external abrasives (sand)] or whole grass hay fed for 2 weeks each in random order to 16 guinea pigs on incisor growth and wear, and tooth length of incisors and cheek teeth. There was a positive correlation between wear and growth of incisors. Tooth lengths depended both on internal and external abrasives, but only upper incisors were additionally affected by the feeding of whole hay. Diet effects were most prominent in anterior cheek teeth, in particular M1 and m1. Cheek tooth angle did not become shallower with decreasing diet abrasiveness, suggesting that a lack of dietary abrasiveness does not cause the typical 'bridge formation' of anterior cheek teeth frequently observed in guinea pigs. The findings suggest that other factors than diet abrasiveness, such as mineral imbalances and in particular hereditary malocclusion, are more likely causes for dental problems observed in this species. PMID:25041439

  16. The Contribution of Abrasion and Size-Selective Sorting to Downstream Fining in a Tropical Montane Stream

    NASA Astrophysics Data System (ADS)

    Szabo, T.; Miller, K. L.; Jerolmack, D. J.; Domokos, G.

    2014-12-01

    Quantifying the effect of abrasion vs. size-selective transport on downstream diminution of grain size and mass is a long-standing question in fluvial systems. While some authors have emphasized sorting by size-selective transport as the dominant fining mechanism in various rivers, others demonstrated the effectiveness of abrasion in certain fluvial systems. We present a synthetic grain-scale model in which we combine a recently developed geometric abrasion model (the so-called 'box equations' [1]) with a simplistic selective deposition rule. Box equations are capable to describe the evolution of both the shape and the size of the particles during abrasion, as opposed to previous models which only dealt with the size (or alternatively, the mass) diminution. We adapt our synthetic model to numerically simulate the downstream grain size and shape evolution in a short tropical river in Puerto Rico where we conducted a detailed field study. By switching off abrasion and selective deposition separately in the numerical model, the individual effects of these two processes can be examined. Based on our simplistic model we deduce that 1/3 of the mass of the grains may be lost only by abrasion in the examined river system. [1] Domokos, G., and G. W. Gibbons (2012), The evolution of pebble size and shape in space and time, Proc. R. Soc. A, 468(2146), 3059-3079, doi:10.1098/rspa.2011.0562.

  17. Ceramic powder for sintering materials

    NASA Technical Reports Server (NTRS)

    Akiya, H.; Saito, A.

    1984-01-01

    Surface activity of ceramic powders such as MgO and Al2O3, for use in sintering with sp. emphasis on their particle size, shape, particle size distribution, packing, and coexisting additives and impurities are reviewed.

  18. Rotary powder feed through apparatus

    DOEpatents

    Lewis, Gary K.; Less, Richard M.

    2001-01-01

    A device for increasing the uniformity of solids within a solids fabrication system, such as a direct light fabrication (DLF) system in which gas entrained powders are passed through the focal point of a moving high-power light which fuses the particles in the powder to a surface being built up in layers. The invention provides a feed through interface wherein gas entrained powders input from stationary input lines are coupled to a rotating head of the fabrication system. The invention eliminates the need to provide additional slack in the feed lines to accommodate head rotation, and therefore reduces feed line bending movements which induce non-uniform feeding of gas entrained powder to a rotating head.

  19. Rock Abrasion as Seen by the MSL Curiosity Rover: Insights on Physical Weathering on Mars

    NASA Astrophysics Data System (ADS)

    Bridges, N.; Day, M. D.; Le Mouelic, S.; Martin-Torres, F. J.; Newsom, H. E.; Sullivan, R. J., Jr.; Ullan, A.; Wiens, R. C.; Zorzano, M. P.

    2014-12-01

    Mars is a dry planet, with actively blowing sand in many regions. In the absence of stable liquid water and an active hydrosphere, rates of chemical weathering are slow, such that aeolian abrasion is a dominant agent of landscape modification where sand is present and winds above threshold occur at sufficient frequency. Reflecting this activity, ventifacts, rocks that have been abraded by windborne particles, and wind-eroded outcrops, are common. They provide invaluable markers of the Martian wind record and insight into climate and landscape modification. Ventifacts are distributed along the traverse of the Mars Science Laboratory Curiosity rover. They contain one or more diagnostic features and textures: Facets, keels, basal sills, elongated pits, scallops/flutes, grooves, rock tails, and lineations. Keels at the junction of facets are sharp enough to pose a hazard MSL's wheels in some areas. Geomorphic and textural patterns on outcrops indicate retreat of windward faces. Moonlight Valley and other depressions are demarcated by undercut walls and scree boulders, with the valley interiors containing fewer rocks, most of which show evidence for significant abrasion. Together, this suggests widening and undercutting of the valley walls, and erosion of interior rocks, by windblown sand. HiRISE images do not show any dark sand dunes in the traverse so far, in contrast to the large dune field to the south that is migrating up to 2 m per year. In addition, ChemCam shows that the rock Bathurst has a rind rich in mobile elements that would be removed in an abrading environment. This indicates that rock abrasion was likely more dominant in the past, a hypothesis consistent with rapid scarp retreat as suggested by the cosmogenic noble gases in Yellowknife Bay. Ventifacts and evidence for bedrock abrasion have also been found at the Pathfinder, Spirit, and Opportunity sites, areas, like the Curiosity traverse so far, that lack evidence for current high sand fluxes. Yardangs

  20. Abrasions and lameness in piglets born in different farrowing systems with different types of floor

    PubMed Central

    Zoric, Mate; Nilsson, Ebba; Mattsson, Sigbrit; Lundeheim, Nils; Wallgren, Per

    2008-01-01

    Background The quality of the floor is essential to the welfare of piglets as abrasions often are recorded in newborn piglets, and such lesions may lead to lameness. Apart from animal suffering, lameness contributes to losses in form of dead piglets, decreased growth, and increased use of antibiotics and manual labour. Methods In a herd with three different farrowing systems, 37 litters (390 piglets) were studied until the age of 3 weeks with respect to presence of skin wounds and abrasions. Lameness was registered until the age of 7 weeks. Eight lame piglets were sacrificed before medical treatment and subjected to necropsy including histopathological and microbiological examinations. Isolates of streptococci, staphylococci and E. coli were tested with respect to antimicrobial resistance. Mastitis was observed in ten sows. Results The most severe abrasions at carpus and soles were seen in the system with a new solid concrete floor with a slatted floor over the dunging area. The lowest magnitude was observed in the deep litter system with peat. Sole bruising was more common in the systems with concrete floor compared to the deep litter system with peat, and the differce in prevalence was significant at all examination days. The lesions decreased with time and about 75% of the treatments for lameness were performed during the first three weeks of life. The overall prevalence of lameness was highest in the system with new solid concrete floor with a slatted floor over the dunging area (9.4%) followed by the old solid concrete floor (7.5%). A lower (p < 0.05) prevalence was seen in the deep litters system with peat (3.3%). No significant relationship between mastitis and abrasions or lameness in the offspring was observed. Conclusion There were large differences in the prevalence of abrasions and lameness between the floor types. The deep litter system with peat provided a soft and good floor for piglets. The overall prevalence of lameness was only diagnosed in every