DETERMINATION OF THE MASS TRANSFER CHARACTERIZATION OF A CERAMIC-POLYMER COMPOSITE MEMBRANE IN THE PERVAPORATION MODE

EPA Science Inventory

The effect of the coating layer thickness on VOC extraction performance of a ceramic polymer composite membrane has been investigated. It was found, under experimental condiitons representing typical field operation, the overall mass transfer rates of feed components were control...

Engine materials characterization and damage monitoring by using x ray technologies

NASA Technical Reports Server (NTRS)

Baaklini, George Y.

1993-01-01

X ray attenuation measurement systems that are capable of characterizing density variations in monolithic ceramics and damage due to processing and/or mechanical testing in ceramic and intermetallic matrix composites are developed and applied. Noninvasive monitoring of damage accumulation and failure sequences in ceramic matrix composites is used during room-temperature tensile testing. This work resulted in the development of a point-scan digital radiography system and an in situ x ray material testing system. The former is used to characterize silicon carbide and silicon nitride specimens, and the latter is used to image the failure behavior of silicon-carbide-fiber-reinforced, reaction-bonded silicon nitride matrix composites. State-of-the-art x ray computed tomography is investigated to determine its capabilities and limitations in characterizing density variations of subscale engine components (e.g., a silicon carbide rotor, a silicon nitride blade, and a silicon-carbide-fiber-reinforced beta titanium matrix rod, rotor, and ring). Microfocus radiography, conventional radiography, scanning acoustic microscopy, and metallography are used to substantiate the x ray computed tomography findings. Point-scan digital radiography is a viable technique for characterizing density variations in monolithic ceramic specimens. But it is very limited and time consuming in characterizing ceramic matrix composites. Precise x ray attenuation measurements, reflecting minute density variations, are achieved by photon counting and by using microcollimators at the source and the detector. X ray computed tomography is found to be a unique x ray attenuation measurement technique capable of providing cross-sectional spatial density information in monolithic ceramics and metal matrix composites. X ray computed tomography is proven to accelerate generic composite component development. Radiographic evaluation before, during, and after loading shows the effect of preexisting volume flaws on the fracture behavior of composites. Results from one-, three-, five-, and eight-ply ceramic composite specimens show that x ray film radiography can monitor damage accumulation during tensile loading. Matrix cracking, fiber-matrix debonding, fiber bridging, and fiber pullout are imaged throughout the tensile loading of the specimens. In situ film radiography is found to be a practical technique for estimating interfacial shear strength between the silicon carbide fibers and the reaction-bonded silicon nitride matrix. It is concluded that pretest, in situ, and post-test x ray imaging can provide greater understanding of ceramic matrix composite mechanical behavior.

Time-dependent reliability analysis of ceramic engine components

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.

1993-01-01

The computer program CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program. CARES/LIFE accounts for the phenomenon of subcritical crack growth (SCG) by utilizing either the power or Paris law relations. The two-parameter Weibull cumulative distribution function is used to characterize the variation in component strength. The effects of multiaxial stresses are modeled using either the principle of independent action (PIA), the Weibull normal stress averaging method (NSA), or the Batdorf theory. Inert strength and fatigue parameters are estimated from rupture strength data of naturally flawed specimens loaded in static, dynamic, or cyclic fatigue. Two example problems demonstrating proof testing and fatigue parameter estimation are given.

Ceramic Inclusions In Powder Metallurgy Disk Alloys: Characterization and Modeling

NASA Technical Reports Server (NTRS)

Bonacuse, Pete; Kantzos, Pete; Telesman, Jack

2002-01-01

Powder metallurgy alloys are increasingly used in gas turbine engines, especially as the material chosen for turbine disks. Although powder metallurgy materials have many advantages over conventionally cast and wrought alloys (higher strength, higher temperature capability, etc.), they suffer from the rare occurrence of ceramic defects (inclusions) that arise from the powder atomization process. These inclusions can have potentially large detrimental effect on the durability of individual components. An inclusion in a high stress location can act as a site for premature crack initiation and thereby considerably reduce the fatigue life. Because these inclusions are exceedingly rare, they usually don't reveal themselves in the process of characterizing the material for a particular application (the cumulative volume of the test bars in a fatigue life characterization is typically on the order of a single actual component). Ceramic inclusions have, however, been found to be the root cause of a number of catastrophic engine failures. To investigate the effect of these inclusions in detail, we have undertaken a study where a known population of ceramic particles, whose composition and morphology are designed to mimic the 'natural' inclusions, are added to the precursor powder. Surface connected inclusions have been found to have a particularly large detrimental effect on fatigue life, therefore the volume of ceramic 'seeds' added is calculated to ensure that a minimum number will occur on the surface of the fatigue test bars. Because the ceramic inclusions are irregularly shaped and have a tendency to break up in the process of extrusion and forging, a method of calculating the probability of occurrence and expected intercepted surface and embedded cross-sectional areas were needed. We have developed a Monte Carlo simulation to determine the distributions of these parameters and have verified the simulated results with observations of ceramic inclusions found in macro slices from extrusions and forgings. The ultimate goal of this study will be to use probabilistic methods to determine the reliability detriment that can be attributed to these ceramic inclusions.

Integration Science and Technology of Silicon-Based Ceramics and Composites:Technical Challenges and Opportunities

NASA Technical Reports Server (NTRS)

Singh, M.

2013-01-01

Ceramic integration technologies enable hierarchical design and manufacturing of intricate ceramic and composite parts starting with geometrically simpler units that are subsequently joined to themselves and/or to metals to create components with progressively higher levels of complexity and functionality. However, for the development of robust and reliable integrated systems with optimum performance for high temperature applications, detailed understanding of various thermochemical and thermomechanical factors is critical. Different technical approaches are required for the integration of ceramic to ceramic and ceramic to metal systems. Active metal brazing, in particular, is a simple and cost-effective method to integrate ceramic to metallic components. Active braze alloys usually contain a reactive filler metal (e.g., Ti, Cr, V, Hf etc) that promotes wettability and spreading by inducing chemical reactions with the ceramics and composites. In this presentation, various examples of brazing of silicon nitride to themselves and to metallic systems are presented. Other examples of joining of ceramic composites (C/SiC and SiC/SiC) using ceramic interlayers and the resulting microstructures are also presented. Thermomechanical characterization of joints is presented for both types of systems. In addition, various challenges and opportunities in design, fabrication, and testing of integrated similar (ceramic-ceramic) and dissimilar (ceramic-metal) material systems will be discussed. Potential opportunities and need for the development of innovative design philosophies, approaches, and integrated system testing under simulated application conditions will also be presented.

The influence of clay fineness upon sludge recycling in a ceramic matrix

NASA Astrophysics Data System (ADS)

Szőke, A. M.; Muntean, M.; Sándor, M.; Brotea, L.

2016-04-01

The feasibility of sludge recycling in the ceramic manufacture was evaluated through laboratory testing. Such residues have similar chemical and mineralogical composition with the raw mixture of the green ceramic body used in construction. Several ceramic masses with clay and various proportion of sludge have been synthesized and then characterized by their physical-mechanical properties. The fineness of the clay, the main component of the green ceramic body, has been considered for every raw mixture. The proportion of the sludge waste addition depends on the clay fineness and the sintering capacity also, increases with the clay fineness. The ceramic properties, particularly, the open porosity, and mechanical properties, in presence of small sludge proportion (7, 20%) shows small modification. The introduction of such waste into building ceramic matrix (bricks, tiles, and plates) has a very good perspective.

Joining of Silicon Carbide Through the Diffusion Bonding Approach

NASA Technical Reports Server (NTRS)

Halbig, Michael .; Singh, Mrityunjay

2009-01-01

In order for ceramics to be fully utilized as components for high-temperature and structural applications, joining and integration methods are needed. Such methods will allow for the fabrication the complex shapes and also allow for insertion of the ceramic component into a system that may have different adjacent materials. Monolithic silicon carbide (SiC) is a ceramic material of focus due to its high temperature strength and stability. Titanium foils were used as an interlayer to form diffusion bonds between chemical vapor deposited (CVD) SiC ceramics with the aid of hot pressing. The influence of such variables as interlayer thickness and processing time were investigated to see which conditions contributed to bonds that were well adhered and crack free. Optical microscopy, scanning electron microscopy, and electron microprobe analysis were used to characterize the bonds and to identify the reaction formed phases.

Progress report

NASA Technical Reports Server (NTRS)

Abhiraman, A.; Collard, D.; Cardelino, B.; Bhatia, S.; Desai, P.; Harruna, I.; Khan, I.; Mariam, Y.; Mensah, T.; Mitchell, M.

1992-01-01

The NASA funding allowed Clark Atlanta University (CAU) to establish a High Performance Polymers And Ceramics (HiPPAC) Research Center. The HiPPAC Center is consolidating and expanding the existing polymer and ceramic research capabilities at CAU through the development of interdepartmental and interinstitutional research in: (1) polymer synthesis; (2) polymer characterization and properties; (3) polymer processing; (4) polymer-based ceramic synthesis; and (5) ceramic characterization and properties. This Center has developed strong interactions between scientists and materials scientists of CAU and their counterparts from sister institutions in the Atlanta University Center (AUC) and the Georgia Institute of Technology. As a component of the center, we have started to develop strong collaborations with scientists from other universities and the HBCU's, national and federal agency laboratories, and the private sector during this first year. During this first year we have refined the focus of the research in the HiPPAC Center to three areas with seven working groups that will start programmatic activities on January 1, 1993, as follows: (1) nonlinear optical properties of chitosan derivatives; (2) polymeric electronic materials; (3) nondestructive characterization and prediction of polyimide performance; (4) solution processing of high-performance materials; (5) processable polyimides for composite applications; (6) sol-gel based ceramic materials processing; and (7) synthetic based processing of pre-ceramic polymers.

Durability evaluation of ceramic components using CARES/LIFE

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Powers, Lynn M.; Janosik, Lesley A.; Gyekenyesi, John P.

1994-01-01

The computer program CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program. CARES/LIFE accounts for the phenomenon of subcritical crack growth (SCG) by utilizing the power law, Paris law, or Walker equation. The two-parameter Weibull cumulative distribution function is used to characterize the variation in component strength. The effects of multiaxial stresses are modeled using either the principle of independent action (PIA), the Weibull normal stress averaging method (NSA), or the Batdorf theory. Inert strength and fatigue parameters are estimated from rupture strength data of naturally flawed specimens loaded in static, dynamic, or cyclic fatigue. Application of this design methodology is demonstrated using experimental data from alumina bar and disk flexure specimens which exhibit SCG when exposed to water.

Durability evaluation of ceramic components using CARES/LIFE

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

Nemeth, N.N.; Janosik, L.A.; Gyekenyesi, J.P.

1996-01-01

The computer program CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program. CARES/LIFE accounts for the phenomenon of subcritical crack growth (SCG) by utilizing the power law, Paris law, or Walker equation. The two-parameter Weibull cumulative distribution function is used to characterize the variation in component strength. The effects of multiaxial stresses are modeled using either the principle of independent action (PIA), the Weibull normal stress averaging method (NSA), or the Batdorf theory. Inert strength andmore » fatigue parameters are estimated from rupture strength data of naturally flawed specimens loaded in static, dynamic, or cyclic fatigue. Application of this design methodology is demonstrated using experimental data from alumina bar and disk flexure specimens, which exhibit SCG when exposed to water.« less

Lifetime Reliability Evaluation of Structural Ceramic Parts with the CARES/LIFE Computer Program

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Powers, Lynn M.; Janosik, Lesley A.; Gyekenyesi, John P.

1993-01-01

The computer program CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program. CARES/LIFE accounts for the phenomenon of subcritical crack growth (SCG) by utilizing the power law, Paris law, or Walker equation. The two-parameter Weibull cumulative distribution function is used to characterize the variation in component strength. The effects of multiaxial stresses are modeled using either the principle of independent action (PIA), Weibull's normal stress averaging method (NSA), or Batdorf's theory. Inert strength and fatigue parameters are estimated from rupture strength data of naturally flawed specimens loaded in static, dynamic, or cyclic fatigue. Two example problems demonstrating cyclic fatigue parameter estimation and component reliability analysis with proof testing are included.

Low temperature joining of ceramic composites

DOEpatents

Barton, Thomas J.; Anderson, Iver E.; Ijadi-Maghsoodi, Sina; Nosrati, Mohammad; Unal, Ozer

1999-07-13

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 degrees C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or ceramic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 degrees C. to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix.

Low temperature joining of ceramic composites

DOEpatents

Barton, T.J.; Anderson, I.E.; Ijadi-Maghsoodi, S.; Nosrati, M.; Unal, O.

1999-07-13

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or ceramic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 C to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix. 3 figs.

Low temperature joining of ceramic composites

DOEpatents

Barton, T.J.; Anderson, I.E.; Ijadi-Maghsoodi, S.; Nosrati, M.; Unal, O.

1999-01-12

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 degrees C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or ceramic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 degrees C. to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix. 3 figs.

Ceramic Inclusions in Powder Metallurgy Disk Alloys: Characterization and Modeling

NASA Technical Reports Server (NTRS)

Bonacuse, Peter J.

2001-01-01

Powder metallurgy alloys are increasingly used in gas turbine engines, especially in turbine disk applications. Although powder metallurgy materials have many advantages over conventionally cast and wrought alloys (higher strength, higher temperature capability, etc.), they suffer from the rare occurrence of ceramic defects (inclusions) that are inherent to the powder atomization process. These inclusions can have a potentially large detrimental effect on the durability of individual components. An inclusion in a high stress location can act as a site for premature crack initiation and thereby considerably reduce the fatigue life. Because these inclusions are exceedingly rare, they typically do not reveal themselves in the process of characterizing the material for a particular application (the cumulative volume of the test bars in a fatigue life characterization is typically on the order of a single actual component). Ceramic inclusions have, however, been found to be the root cause of a number of catastrophic engine failures. To investigate the effect of these inclusions in detail, we have undertaken a study where known populations of ceramic particles, whose composition and morphology are designed to mimic the "natural" inclusions, are added to the precursor powder. Surface-connected inclusions have been found to have a particularly large detrimental effect on fatigue life; therefore, the quantity of ceramic "seeds" added is calculated to ensure that a minimum number will intersect the surface of the fatigue test bars. Because the ceramic inclusions are irregularly shaped and have a tendency to break up in the process of extrusion and forging, a method of calculating the probability of occurrence and expected intercepted surface area was needed. We have developed a Monte Carlo simulation to determine the distributions of these parameters and have verified the simulated results with observations of ceramic inclusions found in macroscopic slices from extrusions and forgings. Fatigue specimens have been machined from Udimet 720 (a powder metallurgy superalloy) forgings, to determine the effects of the inclusions on fatigue life. The ultimate goal of this study will be to use probabilistic methods to determine the reliability detriment that can be attributed to these ceramic inclusions. This work has been supported by the Ultra Safe and Ultra- Efficient Engine Technologies programs.

Method of forming a ceramic matrix composite and a ceramic matrix component

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

de Diego, Peter; Zhang, James

A method of forming a ceramic matrix composite component includes providing a formed ceramic member having a cavity, filling at least a portion of the cavity with a ceramic foam. The ceramic foam is deposited on a barrier layer covering at least one internal passage of the cavity. The method includes processing the formed ceramic member and ceramic foam to obtain a ceramic matrix composite component. Also provided is a method of forming a ceramic matrix composite blade and a ceramic matrix composite component.

Ceramic inspection system

DOEpatents

Werve, Michael E [Modesto, CA

2006-05-16

A system for inspecting a ceramic component. The ceramic component is positioned on a first rotary table. The first rotary table rotates the ceramic component. Light is directed toward the first rotary table and the rotating ceramic component. A detector is located on a second rotary table. The second rotary table is operably connected to the first rotary table and the rotating ceramic component. The second rotary table is used to move the detector at an angle to the first rotary table and the rotating ceramic component.

Interdisciplinary research and development on the effects of the nature and properties of ceramic materials in the design of advanced structural components

NASA Technical Reports Server (NTRS)

1978-01-01

An educational development and supportive research program on ceramic materials established to advance design methodology, improve materials, and develop engineers knowledgable in design with and use of high performance ceramic materials is described. Emphasis is on the structures and related materials problems in a ceramic turbine engine, but applications in coal gasification, solar conversion, and magnetohydrodynamic technologies are considered. Progress of various research projects in the areas of new materials, processing, characterization, and nondestructive testing is reported. Fracture toughness determination, extended X-ray absorption fine structure measurements, and grain boundary effects in beta-alumina are among the topics covered.

Characterization and spectroscopic studies of multi-component calcium zinc bismuth phosphate glass ceramics doped with iron ions

NASA Astrophysics Data System (ADS)

Kumar, A. Suneel; Narendrudu, T.; Suresh, S.; Ram, G. Chinna; Rao, M. V. Sambasiva; Tirupataiah, Ch.; Rao, D. Krishna

2018-04-01

Glass ceramics with the composition 10CaF2-20ZnO-(15-x)Bi2O3-55P2O5:x Fe2O3(0≤x≤2.5) were synthesized by melt-quenching technique and heat treatment. These glass ceramics were characterized by XRD and SEM. Spectroscopic studies such as optical absorption, EPR were also carried out on these glass ceramics. From the absorption spectra the observed bands around 438 and 660nm are the octahedral transitions of Fe3+ (d5) ions and another band at about 536 nm is the tetrahedral transition of Fe3+ (d5) ions. The absorption spectrum also consist of a band around 991 nm and is attributed to the octahedral transition of Fe2+ ions. The EPR spectra of the prepared glass ceramics have exhibited two resonance signals one at g1=4.32 and another signal at g2=2.008. The observed decrease in band gap energy up to 2 mol% Fe2O3 doped glass ceramics is an evidence for the change of environment around iron ions and ligands from more covalent to less covalent (ionic) and induces higher concentration of NBOs which causes the depolymerization of the glass ceramic network.

SiC-Based Composite Materials Obtained by Siliconizing Carbon Matrices

NASA Astrophysics Data System (ADS)

Shikunov, S. L.; Kurlov, V. N.

2017-12-01

We have developed a method for fabrication of parts of complicated configuration from composite materials based on SiC ceramics, which employs the interaction of silicon melt with the carbon matrix having a certain composition and porosity. For elevating the operating temperatures of ceramic components, we have developed a method for depositing protective silicon-carbide coatings that is based on the interaction of the silicon melt and vapor with carbon obtained during thermal splitting of hydrocarbon molecules. The new structural ceramics are characterized by higher operating temperatures; chemical stability; mechanical strength; thermal shock, wear and radiation resistance; and parameters stability.

Low temperature joining of ceramic composites

DOEpatents

Barton, Thomas J.; Anderson, Iver E.; Ijadi-Maghsoodi, Sina; Nosrati, Mohammad; Unal, Ozer

1999-01-12

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 degrees C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or cermaic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 degrees C. to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix.

Low temperature joining of ceramic composites

DOEpatents

Barton, Thomas J.; Anderson, Iver E.; Ijadi-Maghsoodi, Sina; Nosrati, Mohammad; Unal, Ozer

2001-04-10

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 degrees C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or cermaic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 degrees C. to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix.

Development of impact design methods for ceramic gas turbine components

NASA Technical Reports Server (NTRS)

Song, J.; Cuccio, J.; Kington, H.

1990-01-01

Impact damage prediction methods are being developed to aid in the design of ceramic gas turbine engine components with improved impact resistance. Two impact damage modes were characterized: local, near the impact site, and structural, usually fast fracture away from the impact site. Local damage to Si3N4 impacted by Si3N4 spherical projectiles consists of ring and/or radial cracks around the impact point. In a mechanistic model being developed, impact damage is characterized as microcrack nucleation and propagation. The extent of damage is measured as volume fraction of microcracks. Model capability is demonstrated by simulating late impact tests. Structural failure is caused by tensile stress during impact exceeding material strength. The EPIC3 code was successfully used to predict blade structural failures in different size particle impacts on radial and axial blades.

CARES/LIFE Ceramics Analysis and Reliability Evaluation of Structures Life Prediction Program

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Powers, Lynn M.; Janosik, Lesley A.; Gyekenyesi, John P.

2003-01-01

This manual describes the Ceramics Analysis and Reliability Evaluation of Structures Life Prediction (CARES/LIFE) computer program. The program calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/or proof test loading. CARES/LIFE is an extension of the CARES (Ceramic Analysis and Reliability Evaluation of Structures) computer program. The program uses results from MSC/NASTRAN, ABAQUS, and ANSYS finite element analysis programs to evaluate component reliability due to inherent surface and/or volume type flaws. CARES/LIFE accounts for the phenomenon of subcritical crack growth (SCG) by utilizing the power law, Paris law, or Walker law. The two-parameter Weibull cumulative distribution function is used to characterize the variation in component strength. The effects of multiaxial stresses are modeled by using either the principle of independent action (PIA), the Weibull normal stress averaging method (NSA), or the Batdorf theory. Inert strength and fatigue parameters are estimated from rupture strength data of naturally flawed specimens loaded in static, dynamic, or cyclic fatigue. The probabilistic time-dependent theories used in CARES/LIFE, along with the input and output for CARES/LIFE, are described. Example problems to demonstrate various features of the program are also included.

Research on the Treatment of Wastewater by Waste Ceramic Adsorption

NASA Astrophysics Data System (ADS)

He, Lingfeng; Zhang, Yongli; Shi, Liang

2018-03-01

The process of preparing porous ceramic with waste porcelain powder as aggregate was researched. The affect of assimilate time on cuprum removal efficiency in wastewater containing copper was investigated. The results show the water copper removal rate increased along with the augment of assimilate time, and the assimilate time is suitable for 35 min; XRD characterizations show the porous ceramic catalyst before and after calcination in active components of X ray diffraction peak position almost had no changes, and the diffraction intensity slightly changed with calcination and absorption, and diffraction peaks became sharper, and its crystallinity was improved. Baking leads to the growth of crystal particles, and the performance of porous ceramics is stable before and after adsorption.

Thin Film Ceramic Strain Sensor Development for High Temperature Environments

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M.; Laster, Kimala L.

2008-01-01

The need for sensors to operate in harsh environments is illustrated by the need for measurements in the turbine engine hot section. The degradation and damage that develops over time in hot section components can lead to catastrophic failure. At present, the degradation processes that occur in the harsh hot section environment are poorly characterized, which hinders development of more durable components, and since it is so difficult to model turbine blade temperatures, strains, etc, actual measurements are needed. The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in harsh environments. The effort at the NASA Glenn Research Center (GRC) to develop high temperature thin film ceramic static strain gauges for application in turbine engines is described, first in the fan and compressor modules, and then in the hot section. The near-term goal of this research effort was to identify candidate thin film ceramic sensor materials and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. A thorough literature search was conducted for ceramics that have the potential for application as high temperature thin film strain gauges chemically and physically compatible with the NASA GRCs microfabrication procedures and substrate materials. Test results are given for tantalum, titanium and zirconium-based nitride and oxynitride ceramic films.

Ceramic components for the AGT 100 engine

NASA Technical Reports Server (NTRS)

Helms, H. E.; Heitman, P. W.

1983-01-01

Historically, automotive gas turbines have not been able to meet requirements of the marketplace with respect to cost, performance, and reliability. However, the development of appropriate ceramic materials has overcome problems related to a need for expensive superalloy components and to limitations regarding the operating temperature. An automotive gas turbine utilizing ceramic components has been developed by a U.S. automobile manufacturer. A 100-horsepower, two-shaft, regenerative engine geometry was selected because it is compatible with manual, automatic, and continuously variable transmissions. Attention is given to the ceramic components, the ceramic gasifier turbine rotor development, the ceramic gasifier scroll, ceramic component testing, and the use of advanced nondestructive techniques for the evaluation of the engine components.

Compliant fuel cell system

DOEpatents

Bourgeois, Richard Scott [Albany, NY; Gudlavalleti, Sauri [Albany, NY

2009-12-15

A fuel cell assembly comprising at least one metallic component, at least one ceramic component and a structure disposed between the metallic component and the ceramic component. The structure is configured to have a lower stiffness compared to at least one of the metallic component and the ceramic component, to accommodate a difference in strain between the metallic component and the ceramic component of the fuel cell assembly.

Fabrication and Testing of Ceramic Matrix Composite Rocket Propulsion Components

NASA Technical Reports Server (NTRS)

Effinger, M. R.; Clinton, R. C., Jr.; Dennis, J.; Elam, S.; Genge, G.; Eckel, A.; Jaskowiak, M. H.; Kiser, J. D.; Lang, J.

2001-01-01

NASA has established goals for Second and Third Generation Reusable Launch Vehicles. Emphasis has been placed on significantly improving safety and decreasing the cost of transporting payloads to orbit. Ceramic matrix composites (CMC) components are being developed by NASA to enable significant increases in safety and engineer performance, while reducing costs. The development of the following CMC components are being pursued by NASA: (1) Simplex CMC Blisk; (2) Cooled CMC Nozzle Ramps; (3) Cooled CMC Thrust Chambers; and (4) CMC Gas Generator. These development efforts are application oriented, but have a strong underpinning of fundamental understanding of processing-microstructure-property relationships relative to structural analyses, nondestructive characterization, and material behavior analysis at the coupon and component and system operation levels. As each effort matures, emphasis will be placed on optimizing and demonstrating material/component durability, ideally using a combined Building Block Approach and Build and Bust Approach.

Program For Evaluation Of Reliability Of Ceramic Parts

NASA Technical Reports Server (NTRS)

Nemeth, N.; Janosik, L. A.; Gyekenyesi, J. P.; Powers, Lynn M.

1996-01-01

CARES/LIFE predicts probability of failure of monolithic ceramic component as function of service time. Assesses risk that component fractures prematurely as result of subcritical crack growth (SCG). Effect of proof testing of components prior to service also considered. Coupled to such commercially available finite-element programs as ANSYS, ABAQUS, MARC, MSC/NASTRAN, and COSMOS/M. Also retains all capabilities of previous CARES code, which includes estimation of fast-fracture component reliability and Weibull parameters from inert strength (without SCG contributing to failure) specimen data. Estimates parameters that characterize SCG from specimen data as well. Written in ANSI FORTRAN 77 to be machine-independent. Program runs on any computer in which sufficient addressable memory (at least 8MB) and FORTRAN 77 compiler available. For IBM-compatible personal computer with minimum 640K memory, limited program available (CARES/PC, COSMIC number LEW-15248).

Chemical Vapor Deposition of Turbine Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Haven, Victor E.

1999-01-01

Ceramic thermal barrier coatings extend the operating temperature range of actively cooled gas turbine components, therefore increasing thermal efficiency. Performance and lifetime of existing ceram ic coatings are limited by spallation during heating and cooling cycles. Spallation of the ceramic is a function of its microstructure, which is determined by the deposition method. This research is investigating metalorganic chemical vapor deposition (MOCVD) of yttria stabilized zirconia to improve performance and reduce costs relative to electron beam physical vapor deposition. Coatings are deposited in an induction-heated, low-pressure reactor at 10 microns per hour. The coating's composition, structure, and response to the turbine environment will be characterized.

Concept for Determining the Life of Ceramic Matrix Composites Using Nondestructive Characterization Techniques

NASA Technical Reports Server (NTRS)

Effinger, Michael; Ellingson, Bill; Spohnholtz, Todd; Koenig, John

2000-01-01

Damping measurements have been taken on ceramic matrix composite (CMC) turbopump blisks in the as fabricated, post proof testing, and post turbopump testing conditions. These results indicate that damping is able to quantify fatigue of the CMC blisk. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction and how changes in damping and ultrasonic elastic modulus data have established the concept as a possibility.

Wear and Reactivity Studies of Melt infiltrated Ceramic Matrix Composite

NASA Technical Reports Server (NTRS)

Jarmon, David C.; Ojard, Greg; Brewer, David N.

2013-01-01

As interest grows in the use of ceramic matrix composites (CMCs) for critical gas turbine engine components, the effects of the CMCs interaction with the adjoining structure needs to be understood. A series of CMC/material couples were wear tested in a custom elevated temperature test rig and tested as diffusion couples, to identify interactions. Specifically, melt infiltrated silicon carbide/silicon carbide (MI SiC/SiC) CMC was tested in combination with a nickel-based super alloy, Waspaloy, a thermal barrier coating, Yttria Stabilized Zirconia (YSZ), and a monolithic ceramic, silicon nitride (Si3N4). To make the tests more representative of actual hardware, the surface of the CMC was kept in the as-received state (not machined) with the full surface features/roughness present. Test results include: scanning electron microscope characterization of the surfaces, micro-structural characterization, and microprobe analysis.

Automated real-time detection of defects during machining of ceramics

DOEpatents

Ellingson, W.A.; Sun, J.

1997-11-18

Apparatus for the automated real-time detection and classification of defects during the machining of ceramic components employs an elastic optical scattering technique using polarized laser light. A ceramic specimen is continuously moved while being machined. Polarized laser light is directed onto the ceramic specimen surface at a fixed position just aft of the machining tool for examination of the newly machined surface. Any foreign material near the location of the laser light on the ceramic specimen is cleared by an air blast. As the specimen is moved, its surface is continuously scanned by the polarized laser light beam to provide a two-dimensional image presented in real-time on a video display unit, with the motion of the ceramic specimen synchronized with the data acquisition speed. By storing known ``feature masks`` representing various surface and sub-surface defects and comparing measured defects with the stored feature masks, detected defects may be automatically characterized. Using multiple detectors, various types of defects may be detected and classified. 14 figs.

Automated real-time detection of defects during machining of ceramics

DOEpatents

Ellingson, William A.; Sun, Jiangang

1997-01-01

Apparatus for the automated real-time detection and classification of defects during the machining of ceramic components employs an elastic optical scattering technique using polarized laser light. A ceramic specimen is continuously moved while being machined. Polarized laser light is directed onto the ceramic specimen surface at a fixed position just aft of the machining tool for examination of the newly machined surface. Any foreign material near the location of the laser light on the ceramic specimen is cleared by an air blast. As the specimen is moved, its surface is continuously scanned by the polarized laser light beam to provide a two-dimensional image presented in real-time on a video display unit, with the motion of the ceramic specimen synchronized with the data acquisition speed. By storing known "feature masks" representing various surface and sub-surface defects and comparing measured defects with the stored feature masks, detected defects may be automatically characterized. Using multiple detectors, various types of defects may be detected and classified.

Noninteractive macroscopic reliability model for whisker-reinforced ceramic composites

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.; Arnold, Steven M.

1990-01-01

Considerable research is underway in the field of material science focusing on incorporating silicon carbide whiskers into silicon nitride and alumina matrices. These composites show the requisite thermal stability and thermal shock resistance necessary for use as components in advanced gas turbines and heat exchangers. This paper presents a macroscopic noninteractive reliability model for whisker-reinforced ceramic composites. The theory is multiaxial and is applicable to composites that can be characterized as transversely isotropic. Enough processing data exists to suggest this idealization encompasses a significantly large class of fabricated components. A qualitative assessment of the model is made by presenting reliability surfaces in several different stress spaces and for different values of model parameters.

Characterization of Subsurface Defects in Ceramic Rods by Laser Scattering and Fractography

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

Zhang, J. M.; Sun, J. G.; Andrews, M. J.

2006-03-06

Silicon nitride ceramics are leading materials being evaluated for valve train components in diesel engine applications. The surface and subsurface defects and damage induced by surface machining can significantly affect component strength and lifetime. In this study, a nondestructive evaluation (NDE) technique based upon laser scattering has been utilized to analyze eight transversely ground silicon nitride cylindrical rods before fracture tests. The fracture origins (machining cracks or material-inherent flaws) identified by fractography after fracture testing were correlated with laser scattering images. The results indicate that laser scattering is able to identify possible fracture origin in the silicon nitride subsurface withoutmore » the need for destructive fracture tests.« less

Adhesive strength of total knee endoprostheses to bone cement - analysis of metallic and ceramic femoral components under worst-case conditions.

PubMed

Bergschmidt, Philipp; Dammer, Rebecca; Zietz, Carmen; Finze, Susanne; Mittelmeier, Wolfram; Bader, Rainer

2016-06-01

Evaluation of the adhesive strength of femoral components to the bone cement is a relevant parameter for predicting implant safety. In the present experimental study, three types of cemented femoral components (metallic, ceramic and silica/silane-layered ceramic) of the bicondylar Multigen Plus knee system, implanted on composite femora were analysed. A pull-off test with the femoral components was performed after different load and several cementing conditions (four groups and n=3 components of each metallic, ceramic and silica/silane-layered ceramic in each group). Pull-off forces were comparable for the metallic and the silica/silane-layered ceramic femoral components (mean 4769 N and 4298 N) under standard test condition, whereas uncoated ceramic femoral components showed reduced pull-off forces (mean 2322 N). Loading under worst-case conditions led to decreased adhesive strength by loosening of the interface implant and bone cement using uncoated metallic and ceramic femoral components, respectively. Silica/silane-coated ceramic components were stably fixed even under worst-case conditions. Loading under high flexion angles can induce interfacial tensile stress, which could promote early implant loosening. In conclusion, a silica/silane-coating layer on the femoral component increased their adhesive strength to bone cement. Thicker cement mantles (>2 mm) reduce adhesive strength of the femoral component and can increase the risk of cement break-off.

Laser Machining of Melt Infiltrated Ceramic Matrix Composite

NASA Technical Reports Server (NTRS)

Jarmon, D. C.; Ojard, G.; Brewer, D.

2012-01-01

As interest grows in considering the use of ceramic matrix composites for critical components, the effects of different machining techniques, and the resulting machined surfaces, on strength need to be understood. This work presents the characterization of a Melt Infiltrated SiC/SiC composite material system machined by different methods. While a range of machining approaches were initially considered, only diamond grinding and laser machining were investigated on a series of tensile coupons. The coupons were tested for residual tensile strength, after a stressed steam exposure cycle. The data clearly differentiated the laser machined coupons as having better capability for the samples tested. These results, along with micro-structural characterization, will be presented.

Turbine component, turbine blade, and turbine component fabrication process

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

Delvaux, John McConnell; Cairo, Ronald Ralph; Parolini, Jason Robert

A turbine component, a turbine blade, and a turbine component fabrication process are disclosed. The turbine component includes ceramic matrix composite plies and a feature configured for preventing interlaminar tension of the ceramic matrix composite plies. The feature is selected from the group consisting of ceramic matrix composite tows or precast insert tows extending through at least a portion of the ceramic matrix composite plies, a woven fabric having fiber tows or a precast insert preventing contact between a first set of the ceramic matrix composite plies and a second set of the ceramic matrix composite plies, and combinations thereof.more » The process includes laying up ceramic matrix composite plies in a preselected arrangement and securing a feature configured for interlaminar tension.« less

Thermal stress analysis of a planar SOFC stack

NASA Astrophysics Data System (ADS)

Lin, Chih-Kuang; Chen, Tsung-Ting; Chyou, Yau-Pin; Chiang, Lieh-Kwang

The aim of this study is, by using finite element analysis (FEA), to characterize the thermal stress distribution in a planar solid oxide fuel cell (SOFC) stack during various stages. The temperature profiles generated by an integrated thermo-electrochemical model were applied to calculate the thermal stress distributions in a multiple-cell SOFC stack by using a three-dimensional (3D) FEA model. The constructed 3D FEA model consists of the complete components used in a practical SOFC stack, including positive electrode-electrolyte-negative electrode (PEN) assembly, interconnect, nickel mesh, and gas-tight glass-ceramic seals. Incorporation of the glass-ceramic sealant, which was never considered in previous studies, into the 3D FEA model would produce more realistic results in thermal stress analysis and enhance the reliability of predicting potential failure locations in an SOFC stack. The effects of stack support condition, viscous behavior of the glass-ceramic sealant, temperature gradient, and thermal expansion mismatch between components were characterized. Modeling results indicated that a change in the support condition at the bottom frame of the SOFC stack would not cause significant changes in thermal stress distribution. Thermal stress distribution did not differ significantly in each unit cell of the multiple-cell stack due to a comparable in-plane temperature profile. By considering the viscous characteristics of the glass-ceramic sealant at temperatures above the glass-transition temperature, relaxation of thermal stresses in the PEN was predicted. The thermal expansion behavior of the metallic interconnect/frame had a greater influence on the thermal stress distribution in the PEN than did that of the glass-ceramic sealant due to the domination of interconnect/frame in the volume of a planar SOFC assembly.

Vibrational Spectroscopy as a Promising Toolbox for Analyzing Functionalized Ceramic Membranes.

PubMed

Kiefer, Johannes; Bartels, Julia; Kroll, Stephen; Rezwan, Kurosch

2018-01-01

Ceramic materials find use in many fields including the life sciences and environmental engineering. For example, ceramic membranes have shown to be promising filters for water treatment and virus retention. The analysis of such materials, however, remains challenging. In the present study, the potential of three vibrational spectroscopic methods for characterizing functionalized ceramic membranes for water treatment is evaluated. For this purpose, Raman scattering, infrared (IR) absorption, and solvent infrared spectroscopy (SIRS) were employed. The data were analyzed with respect to spectral changes as well as using principal component analysis (PCA). The Raman spectra allow an unambiguous discrimination of the sample types. The IR spectra do not change systematically with functionalization state of the material. Solvent infrared spectroscopy allows a systematic distinction and enables studying the molecular interactions between the membrane surface and the solvent.

Characterization of a piezo bendable X-ray mirror.

PubMed

Vannoni, Maurizio; Freijo Martín, Idoia; Siewert, Frank; Signorato, Riccardo; Yang, Fan; Sinn, Harald

2016-01-01

A full-scale piezo bendable mirror built as a prototype for an offset mirror at the European XFEL is characterized. The piezo ceramic elements are glued onto the mirror substrate, side-face on with respect to the reflecting surface. Using a nanometre optical component measuring machine and a large-aperture Fizeau interferometer, the mirror profile and influence functions were characterized, and further analysis was made to investigate the junction effect, hysteresis, twisting and reproducibility.

Ceramic applications in turbine engines

NASA Technical Reports Server (NTRS)

Helms, H. E.; Heitman, P. W.; Lindgren, L. C.; Thrasher, S. R.

1984-01-01

The application of ceramic components to demonstrate improved cycle efficiency by raising the operating temperature of the existing Allison IGI 404 vehicular gas turbine engine is discussed. This effort was called the Ceramic Applications in Turbine Engines (CATE) program and has successfully demonstrated ceramic components. Among these components are two design configurations featuring stationary and rotating caramic components in the IGT 404 engine. A complete discussion of all phases of the program, design, materials development, fabrication of ceramic components, and testing-including rig, engine, and vehicle demonstation test are presented. During the CATE program, a ceramic technology base was established that is now being applied to automotive and other gas turbine engine programs. This technology base is outlined and also provides a description of the CATE program accomplishments.

Influence of Resin Composition on the Defect Formation in Alumina Manufactured by Stereolithography

PubMed Central

Johansson, Emil; Lidström, Oscar; Johansson, Jan; Lyckfeldt, Ola; Adolfsson, Erik

2017-01-01

Stereolithography (SL) is a technique allowing additive manufacturing of complex ceramic parts by selective photopolymerization of a photocurable suspension containing photocurable monomer, photoinitiator, and a ceramic powder. The manufactured three-dimensional object is cleaned and converted into a dense ceramic part by thermal debinding of the polymer network and subsequent sintering. The debinding is the most critical and time-consuming step, and often the source of cracks. In this study, photocurable alumina suspensions have been developed, and the influence of resin composition on defect formation has been investigated. The suspensions were characterized in terms of rheology and curing behaviour, and cross-sections of sintered specimens manufactured by SL were evaluated by SEM. It was found that the addition of a non-reactive component to the photocurable resin reduced polymerization shrinkage and altered the thermal decomposition of the polymer matrix, which led to a reduction in both delamination and intra-laminar cracks. Using a non-reactive component that decomposed rather than evaporated led to less residual porosity. PMID:28772496

Nondestructive evaluation and characterization of damage and repair to continuous-fiber ceramic composite panels.

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

Sun, J. G.; Petrak, D. R.; Pillai, T. A. K.

1998-04-01

Continuous fiber ceramic matrix composites are currently being developed for a variety of high-temperature applications. Because of the high costs of making these components, minor damage incurred during manufacturing or operation must be rewired in order to extend the life of the components. In this study, five ceramic-grade Nicalon{trademark} fiber/SiNC-matrix composite panels were intentionally damaged with a pendulum-type impactor during an impact test. The damaged panels were then repaired at Dow Corning Corporation. Three nondestructive evaluation (NDE) methods were used to study the characteristics of the panels after the damage and again after the panels were repaired. The NDE methodsmore » were X-ray radiography, infrared thermal imaging, and air-coupled ultrasound. The results showed that the impact test induced various types of damage in the panels. The NDE data that were obtained by the three NDE methods were correlated with each other.« less

Investigation of sample preparation on the moldability of ceramic injection molding feedstocks

NASA Astrophysics Data System (ADS)

Ide, Jared

Ceramic injection molding is a desirable option for those who are looking to make ceramic parts with complex geometries. Formulating the feedstock needed to produce ideal parts is a difficult process. In this research a series of feedstock blends will be evaluated for moldability. This was done by investigating their viscosity, and how certain components affect the overall ability to flow. These feedstocks varied waxes, surfactants, and solids loading. A capillary rheometer was used to characterize some of the materials, which led to one batch being selected for molding trials. The parts were sintered and further refinements were made to the feedstock. Solids loading was increased from 77.5% to 82%, which required different ratios of organics to flow. Finally, the ceramic powders were treated to lower their specific surface area before being compounded, which resulted in materials that would process easily through an extruder and exhibit properties suitable for CIM.

Robust Joining and Integration of Advanced Ceramics and Composites: Challenges, Opportunities, and Realities

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay

2006-01-01

Advanced ceramics and fiber reinforced composites are under active consideration for use in a wide variety of high temperature applications within the aeronautics, space transportation, energy, and nuclear industries. The engineering designs of ceramic and composite components require fabrication and manufacturing of large and complex shaped parts of various thicknesses. In many instances, it is more economical to build up complex shapes by joining simple geometrical shapes. In addition, these components have to be joined or assembled with metallic sub-components. Thus, joining and attachment have been recognized as enabling technologies for successful utilization of ceramic components in various demanding applications. In this presentation, various challenges and opportunities in design, fabrication, and testing of high temperature joints in advanced ceramics and ceramic matrix composites will be presented. Silicon carbide based advanced ceramics and fiber reinforced composites in different shapes and sizes, have been joined using an affordable, robust ceramic joining technology. In addition, some examples of metal-ceramic brazing will also be presented. Microstructure and high temperature mechanical properties of joints in silicon carbide ceramics and composites will be reported. Various joint design philosophies and design issues in joining of ceramics and composites will be discussed.

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1994-01-01

Reports technical effort by AlliedSignal Engines in sixth year of DOE/NASA funded project. Topics include: gas turbine engine design modifications of production APU to incorporate ceramic components; fabrication and processing of silicon nitride blades and nozzles; component and engine testing; and refinement and development of critical ceramics technologies, including: hot corrosion testing and environmental life predictive model; advanced NDE methods for internal flaws in ceramic components; and improved carbon pulverization modeling during impact. ATTAP project is oriented toward developing high-risk technology of ceramic structural component design and fabrication to carry forward to commercial production by 'bridging the gap' between structural ceramics in the laboratory and near-term commercial heat engine application. Current ATTAP project goal is to support accelerated commercialization of advanced, high-temperature engines for hybrid vehicles and other applications. Project objectives are to provide essential and substantial early field experience demonstrating ceramic component reliability and durability in modified, available, gas turbine engine applications; and to scale-up and improve manufacturing processes of ceramic turbine engine components and demonstrate application of these processes in the production environment.

Nondestructive Characterization of Low-Velocity Impact Damage in Protective Ceramic Components

DTIC Science & Technology

2013-09-01

for direct improvement of protective systems. 15. SUBJECT TERMS impact, damage, ultrasound, quantitative, modeling 16. SECURITY CLASSIFICATION OF...21 (4), 245–265. 5. McMichael, S.; Fischer, S. Understanding Materials with Instrumented Impact. ME 1989, 47–50. 6. Chacon -Nava, J. G.; Stott, F

A Viscoplastic Constitutive Theory for Monolithic Ceramic Materials. Series 1

NASA Technical Reports Server (NTRS)

Janosik, Lesley A.; Duffy, Stephen F.

1997-01-01

With increasing use of ceramic materials in high temperature structural applications such as advanced heat engine components, the need arises to accurately predict thermomechanical behavior. This paper, which is the first of two in a series, will focus on inelastic deformation behavior associated with these service conditions by providing an overview of a viscoplastic constitutive model that accounts for time-dependent hereditary material deformation (e.g., creep, stress relaxation, etc.) in monolithic structural ceramics. Early work in the field of metal plasticity indicated that inelastic deformations are essentially unaffected by hydrostatic stress. This is not the case, however, for ceramic-based material systems, unless the ceramic is fully dense. The theory presented here allows for fully dense material behavior as a limiting case. In addition, ceramic materials exhibit different time-dependent behavior in tension and compression. Thus, inelastic deformation models for ceramics must be constructed in a fashion that admits both sensitivity to hydrostatic stress and differing behavior in tension and compression. A number of constitutive theories for materials that exhibit sensitivity to the hydrostatic component of stress have been proposed that characterize deformation using time-independent classical plasticity as a foundation. However, none of these theories allow different behavior in tension and compression. In addition, these theories are somewhat lacking in that they are unable to capture creep, relaxation, and rate-sensitive phenomena exhibited by ceramic materials at high temperature. When subjected to elevated service temperatures, ceramic materials exhibit complex thermomechanical behavior that is inherently time-dependent, and hereditary in the sense that current behavior depends not only on current conditions, but also on thermo-mechanical history. The objective of this work is to present the formulation of a macroscopic continuum theory that captures these time-dependent phenomena. Specifically, the overview contained in this paper focuses on the multiaxial derivation of the constitutive model, and examines the scalar threshold function and its attending geometrical implications.

High temperature ceramics for automobile gas turbines. Part 2: Development of ceramic components

NASA Technical Reports Server (NTRS)

Walzer, P.; Koehler, M.; Rottenkolber, P.

1978-01-01

The development of ceramic components for automobile gas turbine engines is described with attention given to the steady and unsteady thermal conditions the ceramics will experience, and their anti-corrosion and strain-resistant properties. The ceramics considered for use in the automobile turbines include hot-pressed Si3N4, reaction-sintered, isostatically pressed Si3N4, hot-pressed SiC, reaction-bonded SiC, and glass ceramics. Attention is given to the stress analysis of ceramic structures and the state of the art of ceramic structural technology is reviewed, emphasizing the use of ceramics for combustion chambers and ceramic shrouded turbomachinery (a fully ceramic impeller).

Joining and Integration of Silicon Carbide for Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Halbig, Michael C.; Singh, Mrityunjay; Coddington, Bryan; Asthana, Rajiv

2010-01-01

The critical need for ceramic joining and integration technologies is becoming better appreciated as the maturity level increases for turbine engine components fabricated from ceramic and ceramic matrix composite materials. Ceramic components offer higher operating temperatures and reduced cooling requirements. This translates into higher efficiencies and lower emissions. For fabricating complex shapes, diffusion bonding of silicon carbide (SiC) to SiC is being developed. For the integration of ceramic parts to the surrounding metallic engine system, brazing of SiC to metals is being developed. Overcoming the chemical, thermal, and mechanical incompatibilities between dissimilar materials is very challenging. This presentation will discuss the types of ceramic components being developed by researchers and industry and the benefits of using ceramic components. Also, the development of strong, crack-free, stable bonds will be discussed. The challenges and progress in developing joining and integration approaches for a specific application, i.e. a SiC injector, will be presented.

Ceramic femoral component fracture in total knee arthroplasty: an analysis using fractography, fourier-transform infrared microscopy, contact radiography and histology.

PubMed

Krueger, Alexander P; Singh, Gurpal; Beil, Frank Timo; Feuerstein, Bernd; Ruether, Wolfgang; Lohmann, Christoph H

2014-05-01

Ceramic components in total knee arthroplasty (TKA) are evolving. We analyze the first case of BIOLOX delta ceramic femoral component fracture. A longitudinal midline fracture in the patellar groove was present, with an intact cement mantle and no bony defects. Fractographic analysis with laser scanning microscopy and white light interferometry showed no evidence of arrest lines, hackles, wake hackles, material flaws, fatigue or crack propagation. Analysis of periprosthetic tissues with Fourier-transform infrared (FT-IR) microscopy, contact radiography, histology, and subsequent digestion and high-speed centrifugation did not show ceramic debris. A macrophage-dominated response was present around polyethylene debris. We conclude that ceramic femoral component failure in this case was related to a traumatic event. Further research is needed to determine the suitability of ceramic components in TKA. Copyright © 2014 Elsevier Inc. All rights reserved.

Characterization techniques to predict mechanical behaviour of green ceramic bodies fabricated by ceramic microstereolithography

NASA Astrophysics Data System (ADS)

Adake, Chandrashekhar V.; Bhargava, Parag; Gandhi, Prasanna

2018-02-01

Ceramic microstereolithography (CMSL) has emerged as solid free form (SFF) fabrication technology in which complex ceramic parts are fabricated from ceramic suspensions which are formulated by dispersing ceramic particles in UV curable resins. Ceramic parts are fabricated by exposing ceramic suspension to computer controlled UV light which polymerizes resin to polymer and this polymer forms rigid network around ceramic particles. A 3-dimensional part is created by piling cured layers one over the other. These ceramic parts are used to build microelectromechanical (MEMS) devices after thermal treatment. In many cases green ceramic parts can be directly utilized to build MEMS devices. Hence characterization of these parts is essential in terms of their mechanical behaviour prior to their use in MEMS devices. Mechanical behaviour of these green ceramic parts depends on cross link density which in turn depends on chemical structure of monomer, concentrations of photoinitiator and UV energy dose. Mechanical behaviour can be determined with the aid of nanoindentation. And extent of crosslinking can be verified with the aid of DSC. FTIR characterization is used to analyse (-C=C-) double bond conversion. This paper explains characterization tools to predict the mechanical behaviour of green ceramic bodies fabricated in CMSL

Investigation of ionic mobility in NASICON-type solid electrolytes

NASA Astrophysics Data System (ADS)

Vyalikh, A.; Vizgalov, V.; Itkis, D. M.; Meyer, D. C.

2016-10-01

Impedance spectroscopy and 7Li NMR have been applied to characterize the lithium conducting glass-ceramics membranes of the Li1.5Al0.5Ge1.5(PO4)3 composition with the NASICON-type structure. The 7Li NMR spectra and T1 relaxation times have been compared for the precursor glass and two glass-ceramics annealed for 2 and 6 hours, and analysed with respect to the ionic conductivity in these materials. The 7Li static NMR spectra reveal two components in the glass-ceramics samples: A quadrupole pattern with CQ of 38.7 kHz and 32.5 kHz, and a narrow signal of the Lorentzian or Gaussian lineshape for the samples annealed for 2 and 6 hours, respectively. Variation of the lineshape and the deconvolution parameters point out to the modification of the NASICON framework in the former, which affects the conductivity channels towards improved movement of lithium ions. The NMR data correlate with the conductivity measurements demonstrating enhanced ionic mobility in the glass-ceramics annealed for 2 hours. The 7Li NMR relaxation data seem to be very sensitive to the species with different mobility and reveal the presence of an additional minor component, which can be responsible for decrease of conductivity at longer thermal treatment.

Ceramic automotive Stirling engine program

NASA Technical Reports Server (NTRS)

1986-01-01

The Ceramic Automotive Stirling Engine Program evaluated the application of advanced ceramic materials to an automotive Stirling engine. The objective of the program was to evaluate the technical feasibility of utilizing advanced ceramics to increase peak engine operating temperature, and to evaluate the performance benefits of such an increase. Manufacturing cost estimates were also developed for various ceramic engine components and compared with conventional metallic engine component costs.

Pre-form ceramic matrix composite cavity and a ceramic matrix composite component

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

Monaghan, Philip Harold; Delvaux, John McConnell; Taxacher, Glenn Curtis

A pre-form CMC cavity and method of forming pre-form CMC cavity for a ceramic matrix component includes providing a mandrel, applying a base ply to the mandrel, laying-up at least one CMC ply on the base ply, removing the mandrel, and densifying the base ply and the at least one CMC ply. The remaining densified base ply and at least one CMC ply form a ceramic matrix component having a desired geometry and a cavity formed therein. Also provided is a method of forming a CMC component.

Constitutive Theory Developed for Monolithic Ceramic Materials

NASA Technical Reports Server (NTRS)

Janosik, Lesley A.

1998-01-01

With the increasing use of advanced ceramic materials in high-temperature structural applications such as advanced heat engine components, the need arises to accurately predict thermomechanical behavior that is inherently time-dependent and that is hereditary in the sense that the current behavior depends not only on current conditions but also on the material's thermomechanical history. Most current analytical life prediction methods for both subcritical crack growth and creep models use elastic stress fields to predict the time-dependent reliability response of components subjected to elevated service temperatures. Inelastic response at high temperatures has been well documented in the materials science literature for these material systems, but this issue has been ignored by the engineering design community. From a design engineer's perspective, it is imperative to emphasize that accurate predictions of time-dependent reliability demand accurate stress field information. Ceramic materials exhibit different time-dependent behavior in tension and compression. Thus, inelastic deformation models for ceramics must be constructed in a fashion that admits both sensitivity to hydrostatic stress and differing behavior in tension and compression. A number of constitutive theories for materials that exhibit sensitivity to the hydrostatic component of stress have been proposed that characterize deformation using time-independent classical plasticity as a foundation. However, none of these theories allow different behavior in tension and compression. In addition, these theories are somewhat lacking in that they are unable to capture the creep, relaxation, and rate-sensitive phenomena exhibited by ceramic materials at high temperatures. The objective of this effort at the NASA Lewis Research Center has been to formulate a macroscopic continuum theory that captures these time-dependent phenomena. Specifically, the effort has focused on inelastic deformation behavior associated with these service conditions by developing a multiaxial viscoplastic constitutive model that accounts for time-dependent hereditary material deformation (such as creep and stress relaxation) in monolithic structural ceramics. Using continuum principles of engineering mechanics, we derived the complete viscoplastic theory from a scalar dissipative potential function.

Rapid Prototyping of Continuous Fiber Reinforced Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Vaidyanathan, R.; Green, C.; Phillips, T.; Cipriani, R.; Yarlagadda, S.; Gillespie, J.; Effinger, M.; Cooper, K. C.; Gordon, Gail (Technical Monitor)

2002-01-01

For ceramics to be used as structural components in high temperature applications, their fracture toughness is improved by embedding continuous ceramic fibers. Ceramic matrix composite (CMC) materials allow increasing the overall operating temperature, raising the temperature safety margins, avoiding the need for cooling, and improving the damping capacity, while reducing the weight at the same time. They also need to be reliable and available in large quantities as well. In this paper, an innovative rapid prototyping technique to fabricate continuous fiber reinforced ceramic matrix composites is described. The process is simple, robust and will be widely applicable to a number of high temperature material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The results of mechanical properties and microstructural characterization are presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts at an order of magnitude lower cost than current CVI and PIP processes.

Method and apparatus for ceramic analysis

DOEpatents

Jankowiak, Ryszard J.; Schilling, Chris; Small, Gerald J.; Tomasik, Piotr

2003-04-01

The present invention relates to a method and apparatus for ceramic analysis, in particular, a method for analyzing density, density gradients and/or microcracks, including an apparatus with optical instrumentation for analysis of density, density gradients and/or microcracks in ceramics. The method provides analyzing density of a ceramic comprising exciting a component on a surface/subsurface of the ceramic by exposing the material to excitation energy. The method may further include the step of obtaining a measurement of an emitted energy from the component. The method may additionally include comparing the measurement of the emitted energy from the component with a predetermined reference measurement so as to obtain a density for said ceramic.

Metallic nut for use with ceramic threads

DOEpatents

Norton, Paul F.; Shaffer, James E.

1996-01-01

A nozzle guide vane assembly has ceramic components therein having a conventional thread thereon including a preestablished pitch and having a preestablished rate of thermal expansion. The nozzle guide vane assembly has a metallic components therein having a preestablished rate of thermal expansion being greater that the rate of thermal expansion of the ceramic components is positioned in a gas turbine engine. The metallic component, a nut, has a thread therein including a plurality of crests being spaced on a pitch equal to that of the ceramic component and has a pair of contacting surfaces extending from the plurality of crests. A notch spirally extends intermediate adjacent ones of the plurality of crests and has a preestablished depth which is at least twice the size of the conventional pitch. Furthermore, the pair of contacting surfaces are in contact with only a portion of the threaded surface of the ceramic components.

Tribological Properties of Structural Ceramics

NASA Technical Reports Server (NTRS)

Buckley, Donald H.; Miyoshi, Kazuhisa

1987-01-01

Paper discusses tribological properties of structural ceramics. Function of tribological research is to bring about reduction in adhesion, friction, and wear of mechanical components; to prevent failures; and to provide long, reliable component life, through judicious selection of materials, operating parameters, and lubricants. Paper reviews adhesion, friction, wear, and lubrication of ceramics; anisotropic friction and wear behavior; and effects of surface films and interactions between ceramics and metals. Analogies with metals are made. Both oxide and nonoxide ceramics, including ceramics used as high temperature lubricants, are dicussed.

Effects of Combined Stressing on the Electrical Properties of Film and Ceramic Capacitors

NASA Technical Reports Server (NTRS)

Overton, Eric; Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.

1994-01-01

Advanced power systems which generate, control, and distribute electrical power to many large loads are a requirement for future space exploration missions. The development of high temperature insulating materials and power components constitute a key element in systems which are lightweight, efficient, and are capable of surviving the hostile space environment. In previous work, experiments were carried out to evaluate film and ceramic capacitors for potential use in high temperature applications. The effects of thermal stressing, in air and without electrical bias, on the electrical properties of the capacitors as a function of thermal aging up to 12 weeks were determined. In this work, the combined effects of thermal aging and electrical stresses on the properties of teflon film and ceramic power capacitors were examined. The ceramic capacitors were thermally aged for 35 weeks and the teflon capacitors for 15 weeks at 200 C under full electrical bias and were characterized, on a weekly basis, in terms of their capacitance stability and electrical loss in the frequency range of 50 Hz to 100 kHz. DC leakage current measurements were also obtained. The results obtained represent the influence that short-term thermal aging and electrical bias have on the electrical properties of the power capacitors characterized.

Advanced Turbine Technology Applications Project (ATTAP) 1993 annual report

NASA Technical Reports Server (NTRS)

1994-01-01

This report summarizes work performed by AlliedSignal Engines, a unit of AlliedSignal Aerospace Company, during calendar year 1993, toward development and demonstration of structural ceramic technology for automotive gas turbine engines. This work was performed for the U.S. Department of Energy (DOE) under National Aeronautics and Space Administration (NASA) Contract DEN3-335, Advanced Turbine Technology Applications Project (ATFAP). During 1993, the test bed used to demonstrate ceramic technology was changed from the AlliedSignal Engines/Garrett Model AGT101 regenerated gas turbine engine to the Model 331-200(CT) engine. The 331-200(CT) ceramic demonstrator is a fully-developed test platform based on the existing production AlliedSignal 331-200(ER) gas turbine auxiliary power unit (APU), and is well suited to evaluating ceramic turbine blades and nozzles. In addition, commonality of the 331-200(CT) engine with existing gas turbine APU's in commercial service provides the potential for field testing of ceramic components. The 1993 ATTAP activities emphasized design modifications of the 331-200 engine test bed to accommodate ceramic first-stage turbine nozzles and blades, fabrication of the ceramic components, ceramic component proof and rig tests, operational tests of the test bed equipped with the ceramic components, and refinement of critical ceramic design technologies.

COMPOSITION AND METHOD FOR COATING A CERAMIC BODY

DOEpatents

Blanchard, M.K.

1958-11-01

A method is presented for protecting a beryllium carbide-graphite body. The method consists in providing a ceramic coating which must contain at least one basic oxide component, such as CaO, at least one amphoteric oxide component, such as Al/sub 2/O/sub 3/, and at least one acidic oxide component, such as SiO/ sub 2/. Various specific formulations for this ceramic coating are given and the coating is applied by conventional ceramic techniques.

Characterization of a polymer-infiltrated ceramic-network material

PubMed Central

Corazza, Pedro H.; Zhang, Yu

2015-01-01

Objectives To characterize the microstructure and determine some mechanical properties of a polymer-ingfiltrated ceramic-network (PICN) material (Vita Enamic, Vita Zahnfabrik) available for CAD–CAM systems. Methods Specimens were fabricated to perform quantitative and qualitative analyses of the material’s microstructure and to determine the fracture toughness (KIc), density (ρ), Poisson’s ratio (v) and Young’s modulus (E). KIc was determined using V-notched specimens and the short beam toughness method, where bar-shaped specimens were notched and 3-point loaded to fracture. ρ was calculated using Archimedes principle, and v and E were measured using an ultrasonic thickness gauge with a combination of a pulse generator and an oscilloscope. Results Microstructural analyses showed a ceramic- and a polymer-based interpenetrating network. Mean and standard deviation values for the properties evaluated were: KIc = 1.09 ± 0.05 MPa m1/2, ρ = 2.09 ± 0.01 g/cm3, v = 0.23 ± 0.002 and E = 37.95 ± 0.34 GPa. Significance The PICN material showed mechanical properties between porcelains and resin-based composites, reflecting its microstructural components. PMID:24656471

Characterization of a polymer-infiltrated ceramic-network material.

PubMed

Della Bona, Alvaro; Corazza, Pedro H; Zhang, Yu

2014-05-01

To characterize the microstructure and determine some mechanical properties of a polymer-infiltrated ceramic-network (PICN) material (Vita Enamic, Vita Zahnfabrik) available for CAD-CAM systems. Specimens were fabricated to perform quantitative and qualitative analyses of the material's microstructure and to determine the fracture toughness (KIc), density (ρ), Poisson's ratio (ν) and Young's modulus (E). KIc was determined using V-notched specimens and the short beam toughness method, where bar-shaped specimens were notched and 3-point loaded to fracture. ρ was calculated using Archimedes principle, and ν and E were measured using an ultrasonic thickness gauge with a combination of a pulse generator and an oscilloscope. Microstructural analyses showed a ceramic- and a polymer-based interpenetrating network. Mean and standard deviation values for the properties evaluated were: KIc=1.09±0.05MPam(1/2), ρ=2.09±0.01g/cm(3), ν=0.23±0.002 and E=37.95±0.34GPa. The PICN material showed mechanical properties between porcelains and resin-based composites, reflecting its microstructural components. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Principal Components Analysis on the spectral Bidirectional Reflectance Distribution Function of ceramic colour standards.

PubMed

Ferrero, A; Campos, J; Rabal, A M; Pons, A; Hernanz, M L; Corróns, A

2011-09-26

The Bidirectional Reflectance Distribution Function (BRDF) is essential to characterize an object's reflectance properties. This function depends both on the various illumination-observation geometries as well as on the wavelength. As a result, the comprehensive interpretation of the data becomes rather complex. In this work we assess the use of the multivariable analysis technique of Principal Components Analysis (PCA) applied to the experimental BRDF data of a ceramic colour standard. It will be shown that the result may be linked to the various reflection processes occurring on the surface, assuming that the incoming spectral distribution is affected by each one of these processes in a specific manner. Moreover, this procedure facilitates the task of interpolating a series of BRDF measurements obtained for a particular sample. © 2011 Optical Society of America

Methods for providing ceramic matrix composite components with increased thermal capacity

NASA Technical Reports Server (NTRS)

Steibel, James Dale (Inventor); Utah, David Alan (Inventor)

2001-01-01

A method for enhancing the cooling capability of a turbine component made from a ceramic matrix composite. The method improves the thermal performance of the component by producing a surface having increased cooling capacity, thereby allowing the component to operate at a higher temperature. The method tailors the available surface area on the cooling surface of the composite component by depositing a particulate layer of coarse grained ceramic powders of preselected size onto the surface of the ceramic matrix composite component. The size of the particulate is selectively tailored to match the desired surface finish or surface roughness of the article. The article may be designed to have different surface finishes for different locations, so that the application of different sized powders can provide different cooling capabilities at different locations, if desired. The compositions of the particulates are chemically compatible with the ceramic material comprising the outer surface or portion of the ceramic matrix composite. The particulates are applied using a slurry and incorporated into the article by heating to an elevated temperature without melting the matrix, the particulates or the fiber reinforcement.

Development of a statistically proven injection molding method for reaction bonded silicon nitride, sintering reaction bonded silicon nitride, and sintered silicon nitride

NASA Astrophysics Data System (ADS)

Steiner, Matthias

A statistically proven, series injection molding technique for ceramic components was developed for the construction of engines and gas turbines. The flow behavior of silicon injection-molding materials was characterized and improved. Hot-isostatic-pressing reaction bonded silicon nitride (HIPRBSN) was developed. A nondestructive component evaluation method was developed. An injection molding line for HIPRBSN engine components precombustion chamber, flame spreader, and valve guide was developed. This line allows the production of small series for engine tests.

Agricultural wastes as a resource of raw materials for developing low-dielectric glass-ceramics

PubMed Central

Danewalia, Satwinder Singh; Sharma, Gaurav; Thakur, Samita; Singh, K.

2016-01-01

Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their suitability in microelectronic applications. Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions. The addition of sugarcane leaves ash in rice husk ash promotes the glass formation. Additionally, it prevents the cristobalite phase formation. These materials are inherently porous, which is responsible for low dielectric permittivity i.e. 9 to 40. The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases. The present glass-ceramics exhibit lower losses than similar materials synthesized using conventional minerals. The dielectric permittivity is independent to a wide range of temperature and frequency. The glass-ceramics developed with adequately devitrified phases can be used in microelectronic devices and other dielectric applications. PMID:27087123

Pre-form ceramic matrix composite cavity and method of forming and method of forming a ceramic matrix composite component

DOEpatents

Monaghan, Philip Harold; Delvaux, John McConnell; Taxacher, Glenn Curtis

2015-06-09

A pre-form CMC cavity and method of forming pre-form CMC cavity for a ceramic matrix component includes providing a mandrel, applying a base ply to the mandrel, laying-up at least one CMC ply on the base ply, removing the mandrel, and densifying the base ply and the at least one CMC ply. The remaining densified base ply and at least one CMC ply form a ceramic matrix component having a desired geometry and a cavity formed therein. Also provided is a method of forming a CMC component.

Low Temperature Characterization of Ceramic and Film Power Capacitors

NASA Technical Reports Server (NTRS)

Hammoud, Ahmad; Overton, Eric

1996-01-01

Among the key requirements for advanced electronic systems is the ability to withstand harsh environments while maintaining reliable and efficient operation. Exposures to low temperature as well as high temperature constitute such stresses. Applications where low temperatures are encountered include deep space missions, medical imaging equipment, and cryogenic instrumentation. Efforts were taken to design and develop power capacitors capable of wide temperature operation. In this work, ceramic and film power capacitors were developed and characterized as a function of temperature from 20 C to -185 C in terms of their dielectric properties. These properties included capacitance stability and dielectric loss in the frequency range of 50 Hz to 100 kHz. DC leakage current measurements were also performed on the capacitors. The manuscript presents the results that indicate good operational characteristic behavior and stability of the components tested at low temperatures.

Needs assessment for nondestructive testing and materials characterization for improved reliability in structural ceramics for heat engines

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

Johnson, D.R.; McClung, R.W.; Janney, M.A.

1987-08-01

A needs assessment was performed for nondestructive testing and materials characterization to achieve improved reliability in ceramic materials for heat engine applications. Raw materials, green state bodies, and sintered ceramics were considered. The overall approach taken to improve reliability of structural ceramics requires key inspections throughout the fabrication flowsheet, including raw materials, greed state, and dense parts. The applications of nondestructive inspection and characterization techniques to ceramic powders and other raw materials, green ceramics, and sintered ceramics are discussed. The current state of inspection technology is reviewed for all identified attributes and stages of a generalized flowsheet for advanced structuralmore » ceramics, and research and development requirements are identified and listed in priority order. 164 refs., 3 figs.« less

The synthesis, characterisation and in vivo study of a bioceramic for potential tissue regeneration applications

PubMed Central

Poinern, Gérrard Eddy Jai; Brundavanam, Ravi Krishna; Thi Le, Xuan; Nicholls, Philip K.; Cake, Martin A.; Fawcett, Derek

2014-01-01

Hydroxyapatite (HAP) is a biocompatible ceramic that is currently used in a number of current biomedical applications. Recently, nanometre scale forms of HAP have attracted considerable interest due to their close similarity to the inorganic mineral component of the bone matrix found in humans. In this study ultrafine nanometre scale HAP powders were prepared via a wet precipitation method under the influence of ultrasonic irradiation. The resulting powders were compacted and sintered to form a series of ceramic pellets with a sponge-like structure with varying density and porosity. The crystalline structure, size and morphology of the powders and the porous ceramic pellets were investigated using advanced characterization techniques. The pellets demonstrated good biocompatibility, including mixed cell colonisation and matrix deposition, in vivo following surgical implantation into sheep M. latissimus dorsi. PMID:25168046

Fabrication of ceramic substrate-reinforced and free forms by mandrel plasma spraying metal-ceramic composites

NASA Technical Reports Server (NTRS)

Quentmeyer, R. J.; Mcdonald, G.; Hendricks, R. C.

1985-01-01

Components fabricated of, or coated with, ceramics have lower parasitic cooling requirements. Techniques are discussed for fabricating thin-shell ceramic components and ceramic coatings for applications in rocket or jet engine environments. Thin ceramic shells with complex geometric forms involving convolutions and reentrant surfaces were fabricated by mandrel removal. Mandrel removal was combined with electroplating or plasma spraying and isostatic pressing to form a metal support for the ceramic. Rocket engine thrust chambers coated with 0.08 mm (3 mil) of ZrO2-8Y2O3 had no failures and a tenfold increase in engine life. Some measured mechanical properties of the plasma-sprayed ceramic are presented.

Ceramic Matrix Composite (CMC) Materials Characterization

NASA Technical Reports Server (NTRS)

Calomino, Anthony

2001-01-01

Under the former NASA EPM Program, much initial progress was made in identifying constituent materials and processes for SiC/SiC ceramic composite hot-section components. This presentation discusses the performance benefits of these approaches and elaborates on further constituent and property improvements made under NASA UEET. These include specific treatments at NASA that significantly improve the creep and environmental resistance of the Sylramic(TM) SiC fiber as well as the thermal conductivity and creep resistance of the CVI Sic matrix. Also discussed are recent findings concerning the beneficial effects of certain 2D-fabric architectures and carbon between the BN interphase coating and Sic matrix.

Joining and Assembly of Silicon Carbide-based Advanced Ceramics and Composites for High Temperature Applications

NASA Technical Reports Server (NTRS)

Singh, M.

2004-01-01

Silicon carbide based advanced ceramics and fiber reinforced composites are under active consideration for use in wide variety of high temperature applications within the aeronautics, space transportation, energy, and nuclear industries. The engineering designs of ceramic and composite component require fabrication and manufacturing of large and complex shaped parts of various thicknesses. In many instances, it is more economical to build up complex shapes by joining simple geometrical shapes. In addition these components have to be joined or assembled with metallic sub-components. Thus, joining and attachment have been recognized as enabling technologies for successful utilization of ceramic components in various demanding applications. In this presentation, various challenges and opportunities in design, fabrication, and testing o high temperature joints in ceramic matrix composites will be presented. Silicon carbide based advanced ceramics (CVD and hot pressed), and C/SiC and SiC/SiC composites, in different shapes and sizes, have been joined using an affordable, robust ceramic joining technology (ARCJoinT). Microstructure and high temperature mechanical properties of joints in silicon carbide ceramics and CVI and melt infiltrated SiC matrix composites will,be reported. Various joint design philosophies and design issues in joining of ceramics and composites well be discussed.

Planar ceramic membrane assembly and oxidation reactor system

DOEpatents

Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohm, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, deceased, Paul Nigel

2007-10-09

Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

Planar ceramic membrane assembly and oxidation reactor system

DOEpatents

Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohrn, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, Paul Nigel

2009-04-07

Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

Batch compositions for cordierite ceramics

DOEpatents

Hickman, David L.

1994-07-26

Ceramic products consisting principally of cordierite and a method for making them are provided, the method employing batches comprising a mineral component and a chemical component, the mineral component comprising clay and talc and the chemical component consisting essentially of a combination of the powdered oxides, hydroxides, or hydrous oxides of magnesium, aluminum and silicon. Ceramics made by extrusion and firing of the batches can exhibit low porosity, high strength and low thermal expansion coefficients.

Fabrication of ceramic substrate-reinforced and free forms

NASA Technical Reports Server (NTRS)

Quentmeyer, R. J.; Mcdonald, G.; Hendricks, R. C.

1985-01-01

Components fabricated of, or coated with, ceramics have lower parasitic cooling requirements. Techniques are discussed for fabricating thin-shell ceramic components and ceramic coatings for applications in rocket or jet engine environments. Thin ceramic shells with complex geometric forms involving convolutions and reentrant surfaces were fabricated by mandrel removal. Mandrel removal was combined with electroplating or plasma spraying and isostatic pressing to form a metal support for the ceramic. Rocket engine thrust chambers coated with 0.08 mm (3 mil) of ZrO2-8Y2O3 had no failures and a tenfold increase in engine life. Some measured mechanical properties of the plasma-sprayed ceramic are presented.

Ceramics for engines

NASA Technical Reports Server (NTRS)

Kiser, James D.; Levine, Stanley R.; Dicarlo, James A.

1987-01-01

Structural ceramics were under nearly continuous development for various heat engine applications since the early 1970s. These efforts were sustained by the properties that ceramics offer in the areas of high-temperature strength, environmental resistance, and low density and the large benefits in system efficiency and performance that can result. The promise of ceramics was not realized because their brittle nature results in high sensitivity to microscopic flaws and catastrophic fracture behavior. This translated into low reliability for ceramic components and thus limited their application in engines. For structural ceramics to successfully make inroads into the terrestrial heat engine market requires further advances in low cost, net shape fabrication of high reliability components, and improvements in properties such as toughness, and strength. These advances will lead to very limited use of ceramics in noncritical applications in aerospace engines. For critical aerospace applications, an additional requirement is that the components display markedly improved toughness and noncatastrophic or graceful fracture. Thus the major emphasis is on fiber-reinforced ceramics.

Ceramic Composite Development for Gas Turbine Engine Hot Section Components

NASA Technical Reports Server (NTRS)

DiCarlo, James A.; VANrOODE, mARK

2006-01-01

The development of ceramic materials for incorporation into the hot section of gas turbine engines has been ongoing for about fifty years. Researchers have designed, developed, and tested ceramic gas turbine components in rigs and engines for automotive, aero-propulsion, industrial, and utility power applications. Today, primarily because of materials limitations and/or economic factors, major challenges still remain for the implementation of ceramic components in gas turbines. For example, because of low fracture toughness, monolithic ceramics continue to suffer from the risk of failure due to unknown extrinsic damage events during engine service. On the other hand, ceramic matrix composites (CMC) with their ability to display much higher damage tolerance appear to be the materials of choice for current and future engine components. The objective of this paper is to briefly review the design and property status of CMC materials for implementation within the combustor and turbine sections for gas turbine engine applications. It is shown that although CMC systems have advanced significantly in thermo-structural performance within recent years, certain challenges still exist in terms of producibility, design, and affordability for commercial CMC turbine components. Nevertheless, there exist some recent successful efforts for prototype CMC components within different engine types.

Development of sensors for ceramic components in advanced propulsion systems: Survey and evaluation of measurement techniques for temperature, strain and heat flux for ceramic components in advanced propulsion systems

NASA Technical Reports Server (NTRS)

Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

1988-01-01

The report presents the final results of Tasks 1 and 2, Development of Sensors for Ceramic Components in Advanced Propulsion Systems (NASA program NAS3-25141). During Task 1, an extensive survey was conducted of sensor concepts which have the potential for measuring surface temperature, strain and heat flux on ceramic components for advanced propulsion systems. Each sensor concept was analyzed and evaluated under Task 2; sensor concepts were then recommended for further development. For temperature measurement, both pyrometry and thermographic phosphors are recommended for measurements up to and beyond the melting point of ceramic materials. For lower temperature test programs, the thin-film techniques offer advantages in the installation of temperature sensors. Optical strain measurement techniques are recommended because they offer the possibility of being useful at very high temperature levels. Techniques for the measurement of heat flux are recommended for development based on both a surface mounted sensor and the measurement of the temperature differential across a portion of a ceramic component or metallic substrate.

Novel Approach for Positioning Sensor Lead Wires on SiC-Based Monolithic Ceramic and FRCMC Components/Subcomponents Having Flat and Curved Surfaces

NASA Technical Reports Server (NTRS)

Kiser, J. Douglas; Singh, Mrityunjay; Lei, Jin-Fen; Martin, Lisa C.

1999-01-01

A novel attachment approach for positioning sensor lead wires on silicon carbide-based monolithic ceramic and fiber reinforced ceramic matrix composite (FRCMC) components has been developed. This approach is based on an affordable, robust ceramic joining technology, named ARCJoinT, which was developed for the joining of silicon carbide-based ceramic and fiber reinforced composites. The ARCJoinT technique has previously been shown to produce joints with tailorable thickness and good high temperature strength. In this study, silicon carbide-based ceramic and FRCMC attachments of different shapes and sizes were joined onto silicon carbide fiber reinforced silicon carbide matrix (SiC/ SiC) composites having flat and curved surfaces. Based on results obtained in previous joining studies. the joined attachments should maintain their mechanical strength and integrity at temperatures up to 1350 C in air. Therefore they can be used to position and secure sensor lead wires on SiC/SiC components that are being tested in programs that are focused on developing FRCMCs for a number of demanding high temperature applications in aerospace and ground-based systems. This approach, which is suitable for installing attachments on large and complex shaped monolithic ceramic and composite components, should enhance the durability of minimally intrusive high temperature sensor systems. The technology could also be used to reinstall attachments on ceramic components that were damaged in service.

Development of structural ceramic components for automobile applications

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

Kawamoto, H.

1995-12-01

Development efforts have been made in automobile technologies on heat engines to improve the power performance, the fuel economy, and so on. It is well recognized that ceramic applications are keys to succeed in such advanced heat engines, because of their good mechanical and thermal properties. This paper discusses present automobile applications of structural ceramic components and the expectations in automobile uses. The strength and reliability of mass-produced components for the engines are described with the manufacturing processes. The future R&D directions are recommended for structural ceramics.

Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2018-01-01

Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

Pre-Hispanic ceramics analyzed using PIXE and radiographic techniques

NASA Astrophysics Data System (ADS)

Lima, S. C.; Rizzutto, M. A.; Added, N.; Barbosa, M. D. L.; Trindade, G. F.; Fleming, M. I. D. A.

2011-12-01

Ceramics objects are the most common artifacts found during excavation of archaeological sites and often depicts cultural habits and manufacturing technologies of the culture. The determination of macroscopic and microscopic characteristics of the ceramic objects such as the ceramic porosity, addition of tempers in the clay, main chemical components and the trace elements present in the ceramic can reveal many aspects about the manufacturing processes used by the culture, its degree of development, the provenance of the raw materials and the exchange networks. Also the radiography can help to investigate the manufactured processes, the size of the tempers used and the conservation status of the artifacts. In this present work two non-destructive techniques, radiography and PIXE (Particle Induced X-ray Emission) were used to characterize one set of thirty-six pre-Hispanic ceramic pieces from the Chimu Culture conserved in the Museu de Arqueologia e Etnologia (MAE/USP). The PIXE analyses performed in the external beam setup at LAMFI (Laboratório de Análise de Materiais por Feixes Iônicos) allowed measure the principal chemical elements such as Al, Si, K, Ti, Fe and Ca, present in this group of pieces. X-ray imagings allowed identify the manufacture processes, the granularity of the tempers used, as well as the similarity and the differences between the pieces studied.

Biomechanical comparison of the strength of adhesion of polymethylmethacrylate cement to zirconia ceramic and cobalt-chromium alloy components in a total knee arthroplasty.

PubMed

Kumahashi, Nobuyuki; Uchio, Yuji; Kitamura, Nobuto; Satake, Shigeru; Iwamoto, Mikio; Yasuda, Kazunori

2014-11-01

The purpose of this study was to clarify the biomechanical characteristics of cement-material interfaces for the zirconia ceramic and cobalt-chromium (Co-Cr) alloy femoral components used for total knee arthroplasty. In the first sub-study, we compared the strength of adhesion of the cement to flat plates, by tensile testing under dry and moistened conditions. In the second sub-study, we compared the maximum load of the cement-component complex by tensile testing. In the third sub-study, we compared the fatigue characteristics of the cement-component complex by use of a dynamic tensile testing machine. Under dry conditions, the maximum strength of adhesion to the zirconia ceramic plate was the same as that to the Co-Cr alloy plate. Under moistened conditions, however, the strength of adhesion to the zirconia ceramic plate was significantly lower (p = 0.0017) whereas the strength of adhesion to the Co-Cr alloy plate was not reduced. Maximum load for the cement-component complexes for zirconia ceramic and Co-Cr alloy was no different under both dry and moistened conditions. Fatigue testing showed that cement-zirconia adhesion was stronger than cement-Co-Cr alloy adhesion (p = 0.0161). The strength of adhesion of cement to zirconia ceramic is substantially weaker under wet conditions than under dry conditions. The mechanical properties of cement-zirconia ceramic component complexes and cement-Co-Cr alloy component complexes are equivalent.

Turbine repair process, repaired coating, and repaired turbine component

DOEpatents

Das, Rupak; Delvaux, John McConnell; Garcia-Crespo, Andres Jose

2015-11-03

A turbine repair process, a repaired coating, and a repaired turbine component are disclosed. The turbine repair process includes providing a turbine component having a higher-pressure region and a lower-pressure region, introducing particles into the higher-pressure region, and at least partially repairing an opening between the higher-pressure region and the lower-pressure region with at least one of the particles to form a repaired turbine component. The repaired coating includes a silicon material, a ceramic matrix composite material, and a repaired region having the silicon material deposited on and surrounded by the ceramic matrix composite material. The repaired turbine component a ceramic matrix composite layer and a repaired region having silicon material deposited on and surrounded by the ceramic matrix composite material.

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review.

PubMed

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-03-06

Preceramic polymers, i.e. , polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e. , on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix.

Affordable, Robust Ceramic Joining Technology (ARCJoinT) for High Temperature Applications

NASA Technical Reports Server (NTRS)

Singh, M.

1998-01-01

Ceramic joining is recognized as one of the enabling technologies for the successful utilization of silicon carbide-based monolithic ceramic and fiber reinforced composite components in a number of demanding and high temperature applications in aerospace and ground-based systems. An affordable, robust ceramic joining technology (ARCJoinT) for joining of silicon carbide-based ceramics and fiber reinforced composites has been developed. This technique is capable of producing joints with tailorable thickness and composition. A wide variety of silicon carbide-based ceramics and composites, in different shapes and sizes, have been joined using this technique. The room and high temperature mechanical properties and fractography of ceramic joints have been reported. In monolithic silicon carbide ceramics, these joints maintain their mechanical strength up to 1350 C in air. There is no change in the mechanical strength of joints in silicon carbide matrix composites up to 1200 C in air. In composites, simple butt joints yield only about 20% of the ultimate strength of the parent materials. This technology is suitable for the joining of large and complex shaped ceramic and composite components, and with certain modifications, can be applied to repair of ceramic components damaged in service.

Development and Characterization of the Bonding and Integration Technologies Needed for Fabricating Silicon Carbide Based Injector Components

NASA Technical Reports Server (NTRS)

Halbig,Michael C.; Singh, Mrityunjay

2008-01-01

Advanced ceramic bonding and integration technologies play a critical role in the fabrication and application of silicon carbide based components for a number of aerospace and ground based applications. One such application is a lean direct injector for a turbine engine to achieve low NOx emissions. Ceramic to ceramic diffusion bonding and ceramic to metal brazing technologies are being developed for this injector application. For the diffusion bonding technology, titanium interlayers (coatings and foils) were used to aid in the joining of silicon carbide (SiC) substrates. The influence of such variables as surface finish, interlayer thickness, and processing time were investigated. Electron microprobe analysis was used to identify the reaction formed phases. In the diffusion bonds, an intermediate phase, Ti5Si3Cx, formed that is thermally incompatible in its thermal expansion and caused thermal stresses and cracking during the processing cool-down. Thinner interlayers of pure titanium and/or longer processing times resulted in an optimized microstructure. Tensile tests on the joined materials resulted in strengths of 13-28 MPa depending on the SiC substrate material. Nondestructive evaluation using ultrasonic immersion showed well formed bonds. For the joining technology of brazing Kovar fuel tubes to silicon carbide, preliminary development of the joining approach has begun. Various technical issues and requirements for the injector application are addressed.

Ceramic Technology Project semiannual progress report, April 1992--September 1992

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

Johnson, D.R.

1993-07-01

This project was developed to meet the ceramic technology requirements of the DOE Office of Transportation Systems` automotive technology programs. Significant progress in fabricating ceramic components for DOE, NASA, and DOE advanced heat engine programs show that operation of ceramic parts in high-temperature engines is feasible; however, addition research is needed in materials and processing, design, and data base and life prediction before industry will have a sufficient technology base for producing reliable cost-effective ceramic engine components commercially. A 5-yr project plan was developed, with focus on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments,more » and ceramic coatings for thermal barrier and wear applications in these engines.« less

Ceramic components for MHD electrode

DOEpatents

Marchant, D.D.

A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hf/sub x/In/sub y/A/sub z/O/sub 2/ where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a lanthanide rare earth or yttrium. The component is suitable for use in the fabrication of MHD electrodes or as the current leadout portion of a composite electrode with other ceramic components.

Fully-Enclosed Ceramic Micro-burners Using Fugitive Phase and Powder-based Processing

NASA Astrophysics Data System (ADS)

Do, Truong; Shin, Changseop; Kwon, Patrick; Yeom, Junghoon

2016-08-01

Ceramic-based microchemical systems (μCSs) are more suitable for operation under harsh environments such as high temperature and corrosive reactants compared to the more conventional μCS materials such as silicon and polymers. With the recent renewed interests in chemical manufacturing and process intensification, simple, inexpensive, and reliable ceramic manufacturing technologies are needed. The main objective of this paper is to introduce a new powder-based fabrication framework, which is a one-pot, cost-effective, and versatile process for ceramic μCS components. The proposed approach employs the compaction of metal-oxide sub-micron powders with a graphite fugitive phase that is burned out to create internal cavities and microchannels before full sintering. Pure alumina powder has been used without any binder phase, enabling more precise dimensional control and less structure shrinkage upon sintering. The key process steps such as powder compaction, graphite burnout during partial sintering, machining in a conventional machine tool, and final densification have been studied to characterize the process. This near-full density ceramic structure with the combustion chamber and various internal channels was fabricated to be used as a micro-burner for gas sensing applications.

Fully-Enclosed Ceramic Micro-burners Using Fugitive Phase and Powder-based Processing

PubMed Central

Do, Truong; Shin, Changseop; Kwon, Patrick; Yeom, Junghoon

2016-01-01

Ceramic-based microchemical systems (μCSs) are more suitable for operation under harsh environments such as high temperature and corrosive reactants compared to the more conventional μCS materials such as silicon and polymers. With the recent renewed interests in chemical manufacturing and process intensification, simple, inexpensive, and reliable ceramic manufacturing technologies are needed. The main objective of this paper is to introduce a new powder-based fabrication framework, which is a one-pot, cost-effective, and versatile process for ceramic μCS components. The proposed approach employs the compaction of metal-oxide sub-micron powders with a graphite fugitive phase that is burned out to create internal cavities and microchannels before full sintering. Pure alumina powder has been used without any binder phase, enabling more precise dimensional control and less structure shrinkage upon sintering. The key process steps such as powder compaction, graphite burnout during partial sintering, machining in a conventional machine tool, and final densification have been studied to characterize the process. This near-full density ceramic structure with the combustion chamber and various internal channels was fabricated to be used as a micro-burner for gas sensing applications. PMID:27546059

Zirconia-magnesia inert matrix fuel and waste form: Synthesis, characterization and chemical performance in an advanced fuel cycle

NASA Astrophysics Data System (ADS)

Holliday, Kiel Steven

There is a significant buildup in plutonium stockpiles throughout the world, because of spent nuclear fuel and the dismantling of weapons. The radiotoxicity of this material and proliferation risk has led to a desire for destroying excess plutonium. To do this effectively, it must be fissioned in a reactor as part of a uranium free fuel to eliminate the generation of more plutonium. This requires an inert matrix to volumetrically dilute the fissile plutonium. Zirconia-magnesia dual phase ceramic has been demonstrated to be a favorable material for this task. It is neutron transparent, zirconia is chemically robust, magnesia has good thermal conductivity and the ceramic has been calculated to conform to current economic and safety standards. This dissertation contributes to the knowledge of zirconia-magnesia as an inert matrix fuel to establish behavior of the material containing a fissile component. First, the zirconia-magnesia inert matrix is synthesized in a dual phase ceramic containing a fissile component and a burnable poison. The chemical constitution of the ceramic is then determined. Next, the material performance is assessed under conditions relevant to an advanced fuel cycle. Reactor conditions were assessed with high temperature, high pressure water. Various acid solutions were used in an effort to dissolve the material for reprocessing. The ceramic was also tested as a waste form under environmental conditions, should it go directly to a repository as a spent fuel. The applicability of zirconia-magnesia as an inert matrix fuel and waste form was tested and found to be a promising material for such applications.

Reliability and life prediction of ceramic composite structures at elevated temperatures

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.; Gyekenyesi, John P.

1994-01-01

Methods are highlighted that ascertain the structural reliability of components fabricated of composites with ceramic matrices reinforced with ceramic fibers or whiskers and subject to quasi-static load conditions at elevated temperatures. Each method focuses on a particular composite microstructure: whisker-toughened ceramics, laminated ceramic matrix composites, and fabric reinforced ceramic matrix composites. In addition, since elevated service temperatures usually involve time-dependent effects, a section dealing with reliability degradation as a function of load history has been included. A recurring theme throughout this chapter is that even though component failure is controlled by a sequence of many microfailure events, failure of ceramic composites will be modeled using macrovariables.

NASA/CARES dual-use ceramic technology spinoff applications

NASA Technical Reports Server (NTRS)

Powers, Lynn M.; Janosik, Lesley A.; Gyekenyesi, John P.; Nemeth, Noel N.

1994-01-01

NASA has developed software that enables American industry to establish the reliability and life of ceramic structures in a wide variety of 21st Century applications. Designing ceramic components to survive at higher temperatures than the capability of most metals and in severe loading environments involves the disciplines of statistics and fracture mechanics. Successful application of advanced ceramics material properties and the use of a probabilistic brittle material design methodology. The NASA program, known as CARES (Ceramics Analysis and Reliability Evaluation of Structures), is a comprehensive general purpose design tool that predicts the probability of failure of a ceramic component as a function of its time in service. The latest version of this software, CARESALIFE, is coupled to several commercially available finite element analysis programs (ANSYS, MSC/NASTRAN, ABAQUS, COSMOS/N4, MARC), resulting in an advanced integrated design tool which is adapted to the computing environment of the user. The NASA-developed CARES software has been successfully used by industrial, government, and academic organizations to design and optimize ceramic components for many demanding applications. Industrial sectors impacted by this program include aerospace, automotive, electronic, medical, and energy applications. Dual-use applications include engine components, graphite and ceramic high temperature valves, TV picture tubes, ceramic bearings, electronic chips, glass building panels, infrared windows, radiant heater tubes, heat exchangers, and artificial hips, knee caps, and teeth.

Chemically Derived Dense Alumina-Zirconia Composites for Improved Mechanical and Wear Erosion Properties

NASA Technical Reports Server (NTRS)

1998-01-01

As a result of this funded project high purity Zirconia-Toughened Alumina (ZTA) ceramic powders with and without yttria were produced using metal alkoxide precursors. ZTA ceramic powders with varying volume percents of zirconia were prepared (7, 15, and 22%). Aluminum tri-sec butoxide, zirconium propoxide, and yttrium isopropoxide were the reagents used. Synthesis conditions were varied to control the hydrolysis and the aging conditions for the sol to gel transition. FTIR analysis and rheological characterization were used to follow the structural evolution during the sol to gel transition. The greater extent of hydrolysis and the build-up of structure measured from viscoelastic properties were consistent. Heat treatment was conducted to produce submicron grain fully crystalline ZTA ceramic powders. This improved materials should have enhanced properties such strength, toughness, and wear resistance for advanced structural applications, for example engine components in high technology aerospace applications.

Extension of similarity test procedures to cooled engine components with insulating ceramic coatings

NASA Technical Reports Server (NTRS)

Gladden, H. J.

1980-01-01

Material thermal conductivity was analyzed for its effect on the thermal performance of air cooled gas turbine components, both with and without a ceramic thermal-barrier material, tested at reduced temperatures and pressures. The analysis shows that neglecting the material thermal conductivity can contribute significant errors when metal-wall-temperature test data taken on a turbine vane are extrapolated to engine conditions. This error in metal temperature for an uncoated vane is of opposite sign from that for a ceramic-coated vane. A correction technique is developed for both ceramic-coated and uncoated components.

High pressure ceramic joint

DOEpatents

Ward, M.E.; Harkins, B.D.

1993-11-30

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 4 figures.

High pressure ceramic joint

DOEpatents

Ward, Michael E.; Harkins, Bruce D.

1993-01-01

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

High pressure ceramic heat exchanger

DOEpatents

Harkins, Bruce D.; Ward, Michael E.

1998-01-01

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a strengthening reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the strengthening reinforcing member. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

High pressure ceramic heat exchanger

DOEpatents

Harkins, Bruce D.; Ward, Michael E.

1999-01-01

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the reinforcing member and having a strengthening member wrapped around the refractory material. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

High pressure ceramic heat exchanger

DOEpatents

Harkins, B.D.; Ward, M.E.

1998-09-22

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a strengthening reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the strengthening reinforcing member. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 5 figs.

Study of true-remanent polarization using remanent hysteresis task and resistive leakage analysis in ferroelectric 0.64Pb(Mg1/3Nb2/3)O3-0.36PbTiO3 ceramics

NASA Astrophysics Data System (ADS)

Joseph, Abhilash J.; Kumar, Binay

2018-03-01

The conventionally reported value of remanent polarization (Pr) contains contribution from non-remanent components which are not usable for memory device applications. This report presents techniques which extract the true-remanent (intrinsic) component of polarization after eliminating the non-remanent component in ferroelectric ceramics. For this, "remanent hysteresis task" and "positive-up-negative-down technique" were performed which utilized the switchable properties of polarizations to nullify the contributions from the non-remanent (non-switchable) components. The report also addresses the time-dependent leakage behavior of the ceramics focusing on the presence of resistive leakage (a time-dependent parameter) present in the ceramics. The techniques presented here are especially useful for polycrystalline ceramics where leakage current leads to an erroneous estimation of Pr.

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review

PubMed Central

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-01-01

Preceramic polymers, i.e., polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e., on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix. PMID:28788548

Packaging material for thin film lithium batteries

DOEpatents

Bates, John B.; Dudney, Nancy J.; Weatherspoon, Kim A.

1996-01-01

A thin film battery including components which are capable of reacting upon exposure to air and water vapor incorporates a packaging system which provides a barrier against the penetration of air and water vapor. The packaging system includes a protective sheath overlying and coating the battery components and can be comprised of an overlayer including metal, ceramic, a ceramic-metal combination, a parylene-metal combination, a parylene-ceramic combination or a parylene-metal-ceramic combination.

Modeling Oxidation Induced Stresses in Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Ferguson, B. L.; Freborg, A. M.; Petrus, G. J.; Brindley, William J.

1998-01-01

The use of thermal barrier coatings (TBC's) in gas turbines has increased dramatically in recent years, due mainly to the need for component protection from ever increasing service temperatures. Oxidation of the bond coat has been identified as an important contributing factor to spallation of the ceramic top coat during service. Additional variables found to influence TBC thermal cycle life include bond coat coefficient of thermal expansion, creep behavior of both the ceramic and bond coat layers, and modulus of elasticity. The purpose of this work was to characterize the effects of oxidation on the stress states within the TBC system, as well as to examine the interaction of oxidation with other factors affecting TBC life.

Bipolar ferroelectric fatigue in (K0.5Na0.5)(Nb0.7Ta0.3)O3 ceramics and improved fatigue endurance on addition of ZnO

NASA Astrophysics Data System (ADS)

Vineetha, P.; Shanmuga Priya, B.; Venkata Saravanan, K.

2018-04-01

Ferroelectric ceramics are the key components in piezoelectric devices used today, thus long term reliability is a major industrial concern. The two important things that have to be considered in the ferroelectric material based device are aging and fatigue. The first one describes degradation with time whereas the later one is characterized by the change of material property during electrical loading. In the present work ferroelectric polarization and bipolar fatigue properties of undoped and ZnO doped lead free (K0.5Na0.5)(Nb0.7Ta0.3)O3 (KNNT) ceramics prepared by solid state reaction method were investigated. X-ray diffraction analysis of the samples reveal perovskite monoclinic phase along with the secondary phase of K2Nb4O11. The ferroelectric studies indicate that ZnO addition reduce fatigue as well as a well saturated hysteresis loop is obtained. The results reveal that addition of ZnO enhances the ferroelectric properties of KNNT ceramics.

Joining Dental Ceramic Layers With Glass

PubMed Central

Saied, MA; Lloyd, IK; Haller, WK; Lawn, BR

2011-01-01

Objective Test the hypothesis that glass-bonding of free-form veneer and core ceramic layers can produce robust interfaces, chemically durable and aesthetic in appearance and, above all, resistant to delamination. Methods Layers of independently produced porcelains (NobelRondo™ Press porcelain, Nobel BioCare AB and Sagkura Interaction porcelain, Elephant Dental) and matching alumina or zirconia core ceramics (Procera alumina, Nobel BioCare AB, BioZyram yttria stabilized tetragonal zirconia polycrystal, Cyrtina Dental) were joined with designed glasses, tailored to match thermal expansion coefficients of the components and free of toxic elements. Scanning electron microprobe analysis was used to characterize the chemistry of the joined interfaces, specifically to confirm interdiffusion of ions. Vickers indentations were used to drive controlled corner cracks into the glass interlayers to evaluate the toughness of the interfaces. Results The glass-bonded interfaces were found to have robust integrity relative to interfaces fused without glass, or those fused with a resin-based adhesive. Significance The structural integrity of the interfaces between porcelain veneers and alumina or zirconia cores is a critical factor in the longevity of all-ceramic dental crowns and fixed dental prostheses. PMID:21802131

Manufacturing conditioned roughness and wear of biomedical oxide ceramics for all-ceramic knee implants

PubMed Central

2013-01-01

Background Ceramic materials are used in a growing proportion of hip joint prostheses due to their wear resistance and biocompatibility properties. However, ceramics have not been applied successfully in total knee joint endoprostheses to date. One reason for this is that with strict surface quality requirements, there are significant challenges with regard to machining. High-toughness bioceramics can only be machined by grinding and polishing processes. The aim of this study was to develop an automated process chain for the manufacturing of an all-ceramic knee implant. Methods A five-axis machining process was developed for all-ceramic implant components. These components were used in an investigation of the influence of surface conformity on wear behavior under simplified knee joint motion. Results The implant components showed considerably reduced wear compared to conventional material combinations. Contact area resulting from a variety of component surface shapes, with a variety of levels of surface conformity, greatly influenced wear rate. Conclusions It is possible to realize an all-ceramic knee endoprosthesis device, with a precise and affordable manufacturing process. The shape accuracy of the component surfaces, as specified by the design and achieved during the manufacturing process, has a substantial influence on the wear behavior of the prosthesis. This result, if corroborated by results with a greater sample size, is likely to influence the design parameters of such devices. PMID:23988155

Manufacturing conditioned roughness and wear of biomedical oxide ceramics for all-ceramic knee implants.

PubMed

Turger, Anke; Köhler, Jens; Denkena, Berend; Correa, Tomas A; Becher, Christoph; Hurschler, Christof

2013-08-29

Ceramic materials are used in a growing proportion of hip joint prostheses due to their wear resistance and biocompatibility properties. However, ceramics have not been applied successfully in total knee joint endoprostheses to date. One reason for this is that with strict surface quality requirements, there are significant challenges with regard to machining. High-toughness bioceramics can only be machined by grinding and polishing processes. The aim of this study was to develop an automated process chain for the manufacturing of an all-ceramic knee implant. A five-axis machining process was developed for all-ceramic implant components. These components were used in an investigation of the influence of surface conformity on wear behavior under simplified knee joint motion. The implant components showed considerably reduced wear compared to conventional material combinations. Contact area resulting from a variety of component surface shapes, with a variety of levels of surface conformity, greatly influenced wear rate. It is possible to realize an all-ceramic knee endoprosthesis device, with a precise and affordable manufacturing process. The shape accuracy of the component surfaces, as specified by the design and achieved during the manufacturing process, has a substantial influence on the wear behavior of the prosthesis. This result, if corroborated by results with a greater sample size, is likely to influence the design parameters of such devices.

Environmental Barrier Coating Fracture, Fatigue and High-Heat-Flux Durability Modeling and Stochastic Progressive Damage Simulation

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Nemeth, Noel N.

2017-01-01

Advanced environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect emerging light-weight SiC/SiC ceramic matrix composite (CMC) engine components, further raising engine operating temperatures and performance. Because the environmental barrier coating systems are critical to the performance, reliability and durability of these hot-section ceramic engine components, a prime-reliant coating system along with established life design methodology are required for the hot-section ceramic component insertion into engine service. In this paper, we have first summarized some observations of high temperature, high-heat-flux environmental degradation and failure mechanisms of environmental barrier coating systems in laboratory simulated engine environment tests. In particular, the coating surface cracking morphologies and associated subsequent delamination mechanisms under the engine level high-heat-flux, combustion steam, and mechanical creep and fatigue loading conditions will be discussed. The EBC compostion and archtechture improvements based on advanced high heat flux environmental testing, and the modeling advances based on the integrated Finite Element Analysis Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program will also be highlighted. The stochastic progressive damage simulation successfully predicts mud flat damage pattern in EBCs on coated 3-D specimens, and a 2-D model of through-the-thickness cross-section. A 2-parameter Weibull distribution was assumed in characterizing the coating layer stochastic strength response and the formation of damage was therefore modeled. The damage initiation and coalescence into progressively smaller mudflat crack cells was demonstrated. A coating life prediction framework may be realized by examining the surface crack initiation and delamination propagation in conjunction with environmental degradation under high-heat-flux and environment load test conditions.

Interfacial adhesion of dental ceramic-resin systems

NASA Astrophysics Data System (ADS)

Della Bona, Alvaro

The clinical success of resin bonding procedures for indirect ceramic restorations and ceramic repairs depends on the quality and durability of the bond between the ceramic and the resin. The quality of this bond will depend upon the bonding mechanisms that are controlled in part by the surface treatment that promotes micromechanical and/or chemical bonding to the substrate. The objective of this study is to correlate interfacial toughness (K A) with fracture surface morphological parameters of the dental ceramic-resin systems as a function of ceramic surface treatment. The analytical procedures focused on characterizing the microstructure and fracture properties of EmpressRTM ceramics (a leucite-based core ceramic, two lithia disilicate-based core ceramics, and a glass veneer) and determining the ceramic-resin adhesion zone bond strength characteristics. Microstructure and composition are controlling factors in the development of micromechanical retention produced by etching. Silane treated ceramics negated the effect of surface roughening produced by etching, inducing lower surface energy of the ceramic and, reduced bonding effectiveness. There was a positive correlation between WA, tensile bond strength (a), and KA, i.e., higher mean WA value, and higher mean sigma and KA values. This study suggests that (1) the sigma and KA values for ceramic bonded to resin are affected by the ceramic microstructure and the ceramic surface treatments; (2) the definition of the adhesion zone is essential to classify the modes of failure, which should be an integral component of all failure analyses; (3) the microtensile test may be preferable to conventional shear or flexural tests as an indicator of composite-ceramic bond quality; and (4) careful microscopic analysis of fracture surfaces and an x-ray dot map can produce a more consistent and complete description of the fracture process and interpretation of the modes of failure. The mode of failure and fractographic analyses provide important a more comprehensive assessment of mechanisms that control the survival times of dental adhesive systems. Thus, the quality of the bond should not be assessed based on bond strength data alone.

Ceramic-Based 4D Components: Additive Manufacturing (AM) of Ceramic-Based Functionally Graded Materials (FGM) by Thermoplastic 3D Printing (T3DP).

PubMed

Scheithauer, Uwe; Weingarten, Steven; Johne, Robert; Schwarzer, Eric; Abel, Johannes; Richter, Hans-Jürgen; Moritz, Tassilo; Michaelis, Alexander

2017-11-28

In our study, we investigated the additive manufacturing (AM) of ceramic-based functionally graded materials (FGM) by the direct AM technology thermoplastic 3D printing (T3DP). Zirconia components with varying microstructures were additively manufactured by using thermoplastic suspensions with different contents of pore-forming agents (PFA), which were co-sintered defect-free. Different materials were investigated concerning their suitability as PFA for the T3DP process. Diverse zirconia-based suspensions were prepared and used for the AM of single- and multi-material test components. All of the samples were sintered defect-free, and in the end, we could realize a brick wall-like component consisting of dense (<1% porosity) and porous (approx. 5% porosity) zirconia areas to combine different properties in one component. T3DP opens the door to the AM of further ceramic-based 4D components, such as multi-color, multi-material, or especially, multi-functional components.

Ceramic-Based 4D Components: Additive Manufacturing (AM) of Ceramic-Based Functionally Graded Materials (FGM) by Thermoplastic 3D Printing (T3DP)

PubMed Central

Weingarten, Steven; Johne, Robert; Schwarzer, Eric; Richter, Hans-Jürgen; Michaelis, Alexander

2017-01-01

In our study, we investigated the additive manufacturing (AM) of ceramic-based functionally graded materials (FGM) by the direct AM technology thermoplastic 3D printing (T3DP). Zirconia components with varying microstructures were additively manufactured by using thermoplastic suspensions with different contents of pore-forming agents (PFA), which were co-sintered defect-free. Different materials were investigated concerning their suitability as PFA for the T3DP process. Diverse zirconia-based suspensions were prepared and used for the AM of single- and multi-material test components. All of the samples were sintered defect-free, and in the end, we could realize a brick wall-like component consisting of dense (<1% porosity) and porous (approx. 5% porosity) zirconia areas to combine different properties in one component. T3DP opens the door to the AM of further ceramic-based 4D components, such as multi-color, multi-material, or especially, multi-functional components. PMID:29182541

Process for making ceramic insulation

DOEpatents

Akash, Akash [Salt Lake City, UT; Balakrishnan, G Nair [Sandy, UT

2009-12-08

A method is provided for producing insulation materials and insulation for high temperature applications using novel castable and powder-based ceramics. The ceramic components produced using the proposed process offers (i) a fine porosity (from nano-to micro scale); (ii) a superior strength-to-weight ratio; and (iii) flexibility in designing multilayered features offering multifunctionality which will increase the service lifetime of insulation and refractory components used in the solid oxide fuel cell, direct carbon fuel cell, furnace, metal melting, glass, chemical, paper/pulp, automobile, industrial heating, coal, and power generation industries. Further, the ceramic components made using this method may have net-shape and/or net-size advantages with minimum post machining requirements.

Reuse of hazardous calcium fluoride sludge from the integrated circuit industry.

PubMed

Zhu, Ping; Cao, Zhenbang; Ye, YiLi; Qian, Guangren; Lu, Bo; Zhou, Ming; Zhou, Jin

2013-11-01

The Chinese integrated circuit industry has been transformed from a small state-owned sector into a global competitor, but chip manufacturing produces large amounts of calcium fluoride sludges (CFS). In China, landfill is a current option for treating CFS. In order to solve the problem of unavailable landfill sites and prevent fluorine from dissolved CFS polluting water sources, CFS was tested as a component for a ceramic product made with sodium borate, sodium phosphate and waste alumina using a low-temperature sintering technology, and the effects of various factors on characteristics of the ceramic were investigated to optimize the process. The best sintering temperature was controlled at 700°C, and the optimal raw material ratio of the ceramic was 11% sodium borate, 54% sodium phosphate, 30% CFS and 5% waste alumina. The CFS ceramic was characterized by a morphological structure and X-ray diffraction. The results indicated that CFS was transformed into Na2Ca(PO4)F as an inert and a main crystalline phase in the ceramic, which was enclosed by the borophosphate glass. Toxicity characteristic leaching procedure, corrosion resistance and compressive strength tests verified CFS ceramic as a qualified construction ceramic material, and the fluorine from CFS was solidified in the inert crystalline phase, which would not be released to cause secondary pollution. This novel technology not only avoids the CFS hydrolyzing reaction forming harmful hydrofluoric acid gas at 800°C and above, but also produces high-performance ceramics as a construction material, in accordance with the concept of sustainable development.

Method For Removing Volatile Components From A Gel-Cast Ceramic Article

DOEpatents

Klug, Frederic Joseph; DeCarr, Sylvia Marie

2004-09-07

A method of removing substantially all of the volatile component in a green, volatile-containing ceramic article is disclosed. The method comprises freezing the ceramic article; and then subjecting the frozen article to a vacuum for a sufficient time to freeze-dry the article. Frequently, the article is heated while being freeze-dried. Use of this method efficiently reduces the propensity for any warpage of the article. The article is often formed from a ceramic slurry in a gel-casting process. A method for fabricating a ceramic core used in investment casting is also described.

Method for removing volatile components from a ceramic article, and related processes

DOEpatents

Klug, Frederic Joseph; DeCarr, Sylvia Marie

2002-01-01

A method of removing substantially all of the volatile component in a green, volatile-containing ceramic article is disclosed. The method comprises freezing the ceramic article; and then subjecting the frozen article to a vacuum for a sufficient time to freeze-dry the article. Frequently, the article is heated while being freeze-dried. Use of this method efficiently reduces the propensity for any warpage of the article. The article is often formed from a ceramic slurry in a gel-casting process. A method for fabricating a ceramic core used in investment casting is also described.

Improved Slip Casting Of Ceramic Models

NASA Technical Reports Server (NTRS)

Buck, Gregory M.; Vasquez, Peter; Hicks, Lana P.

1994-01-01

Improved technique of investment slip casting developed for making precise ceramic wind-tunnel models. Needed in wind-tunnel experiments to verify predictions of aerothermodynamical computer codes. Ceramic materials used because of their low heat conductivities and ability to survive high temperatures. Present improved slip-casting technique enables casting of highly detailed models from aqueous or nonaqueous solutions. Wet shell molds peeled off models to ensure precise and undamaged details. Used at NASA Langley Research Center to form superconducting ceramic components from nonaqueous slip solutions. Technique has many more applications when ceramic materials developed further for such high-strength/ temperature components as engine parts.

Method for improving the performance of oxidizable ceramic materials in oxidizing environments

NASA Technical Reports Server (NTRS)

Nagaraj, Bangalore A. (Inventor)

2002-01-01

Improved adhesion of thermal barrier coatings to nonmetallic substrates using a dense layer of ceramic on an underlying nonmetallic substrate that includes at least one oxidizable component. The improved adhesion occurs because the application of the dense ceramic layer forms a diffusion barrier for oxygen. This diffusion barrier prevents the oxidizable component of the substrate from decomposing. The present invention applies ceramic by a process that deposits a relatively thick and dense ceramic layer on the underlying substrate. The formation of the dense layer of ceramic avoids the problem of void formation associated with ceramic formation by most prior art thermal decomposition processes. The formation of voids has been associated with premature spalling of thermal barrier layers and other protective layers applied to substrates.

Study and program plan for improved heavy duty gas turbine engine ceramic component development

NASA Technical Reports Server (NTRS)

Helms, H. E.

1977-01-01

Fuel economy in a commercially viable gas turbine engine was demonstrated through use of ceramic materials. Study results show that increased turbine inlet and generator inlet temperatures, through the use of ceramic materials, contribute the greatest amount to achieving fuel economy goals. Improved component efficiencies show significant additional gains in fuel economy.

Ceramic high pressure gas path seal

NASA Technical Reports Server (NTRS)

Liotta, G. C.

1987-01-01

Stage 1 ceramic shrouds (high pressure turbine gas path seal) were developed for the GE T700 turbine helicopter engine under the Army/NASA Contract NAS3-23174. This contract successfully proved the viability and benefits of a Stage 1 ceramic shroud for production application. Stage 1 ceramic shrouds were proven by extensive component and engine testing. This Stage 1 ceramic shroud, plasma sprayed ceramic (ZrOs-BY2O3) and bond coating (NiCrAlY) onto a cast metal backing, offers significant engine performance improvement. Due to the ceramic coating, the amount of cooling air required is reduced 20% resulting in a 0.5% increase in horsepower and a 0.3% decrease in specific fuel consumption. This is accomplished with a component which is lower in cost than the current production shroud. Stage 1 ceramic shrouds will be introduced into field service in late 1987.

Emittance and absorptance of the National Aeronautics and Space Administration ceramic thermal barrier coating. [for gas turbine engine components

NASA Technical Reports Server (NTRS)

Liebert, C. H.

1978-01-01

The spectral emittance of a NASA developed zirconia ceramic thermal barrier coating system, consisting of a metal substrate, a layer of Ni-Cr-Al-Y bond material and a layer of yttria-stabilized zirconia ceramic material, is analyzed. The emittance, needed for evaluation of radiant heat loads on cooled coated gas turbine components, was measured over a range of temperatures that would be typical of its use on such components. Emittance data were obtained with a spectrometer, a reflectometer and a radiation pyrometer at a single bond coating thickness of 0.010 cm and at a ceramic coating thickness of 0-0.076 cm. The data were transformed into the hemispherical total emittance and were correlated to the ceramic coating thickness and temperature using multiple-regression curve-fitting techniques. The system was found to be highly reflective, and, consequently, capable of significantly reducing radiation heat loads on cooled gas turbine engine components.

Development of new materials from waste electrical and electronic equipment: Characterization and catalytic application.

PubMed

Souza, J P; Freitas, P E; Almeida, L D; Rosmaninho, M G

2017-07-01

Wastes of electrical and electronic equipment (WEEE) represent an important environmental problem, since its composition includes heavy metals and organic compounds used as flame-retardants. Thermal treatments have been considered efficient processes on removal of these compounds, producing carbonaceous structures, which, together with the ceramic components of the WEEE (i.e. silica and alumina), works as support material for the metals. This mixture, associated with the metals present in WEEE, represents promising systems with potential for catalytic application. In this work, WEEE was thermally modified to generate materials that were extensively characterized. Raman spectrum for WEEE after thermal treatment showed two carbon associated bands. SEM images showed a metal nanoparticles distribution over a polymeric and ceramic support. After characterization, WEEE materials were applied in ethanol steam reforming reaction. The system obtained at higher temperature (800°C) exhibited the best activity, since it leads to high conversions (85%), hydrogen yield (30%) and H 2 /CO ratio (3,6) at 750°C. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ceramic Matrix Characterization Under a Gas Turbine Combustion and Loading Environment

DTIC Science & Technology

2014-03-17

carrier gas is injected into the jet and melts the powder to create a coating on the material. Figure 11 shows the nozzle of the HVOF spray gun when used...CERAMIC MATRIX COMPOSITE CHARACTERIZATION UNDER A GAS TURBINE COMBUSTION AND LOADING ENVIRONMENT...the United States. AFIT-ENY-14-M-08 CERAMIC MATRIX COMPOSITE CHARACTERIZATION UNDER A GAS TURBINE COMBUSTION AND LOADING ENVIRONMENT

[Clinical evaluation of the ceramic femoral component used for reconstruction of total knee replacement].

PubMed

Vavrík, P; Landor, I; Denk, F

2008-12-01

The study evaluates mid-term results of total knee replacement with a zirconia ceramic (ZrO2) femoral component. The evaluated group comprised 20 knees in 19 patients (4 men and 15 women). In one patient the replacement was performed bilaterally. Two patients had in the contralateral knee the same type of prosthesis with a femoral chrome-cobalt component.The mean age at the time of operation was 65.2 years (range, 38-81 years).The primary indication was 14 times osteoarthritis and 5 times rheumatoid arthritis. The average follow-up period was 6.5 years (range, 2.1-8.5 years). Patients included in the study regardless of age, body mass and the basic diagnosis, agreed with the use of the ceramic femoral component. The evaluation covered a range of motion, mechanical axis, joint stability, pain, swelling, ability to walk on level ground and on stairs, subjective satisfaction (EULAR Knee Chart). Radiograph were assessed at one year intervals in two projections to identify the incidence of radiolucency around the implant. The Kaplan-Meier survival curve was used and compared with the survival curve in identical chrome-cobalt implants. At he final follow-up, 14 knees were evaluated, because 3 patients died without any connection with the implant, in one case the tibial component migrated due to necrosis of the tibial condyle in a patient with RA and two implants had to be revised and replaced due to polyethylene wear. No infection or negative tissue reaction was recorded in the evaluated group. The average flexion range was 109 degrees. All knees were stable and without swelling, in two cases there occurred slight femoropatellar pain. Twelve patients were fully satisfied, 2 patients were satisfied with a certain reservation. The differences in the course of the survival curves of chrome-cobalt and ceramic implants were statistically insignificant. Although the use of zirconia ceramics in vitro reduces the amount of polyethylene wear, the clinical outcomes of total knee replacements as compared to the hip are not convincing. One of the causes may be the substantially different and more complex biomechanics of the knee. Tribology improvement of the femoral ceramic component cannot compensate the deficiencies in the joint balancing in flexion and extension. The economically and technologically demanding production of these implants may be justified in patients with allergies caused by chrome-cobalt components. The results of mid-term follow-up of the use of zirconia ceramic femoral components proved no impact on the improvement of the period of survival of the knee implant. No adverse response to the material or mechanical failure of the ceramic components was encountered. Key words: total knee replacement, zirconia ceramic femoral component, TKR mid-term results, ceramic knee survival curve.

High energy resolution with transparent ceramic garnet scintillators

NASA Astrophysics Data System (ADS)

Cherepy, N. J.; Seeley, Z. M.; Payne, S. A.; Beck, P. R.; Swanberg, E. L.; Hunter, S.; Ahle, L.; Fisher, S. E.; Melcher, C.; Wei, H.; Stefanik, T.; Chung, Y.-S.; Kindem, J.

2014-09-01

Breakthrough energy resolution, R(662keV) < 4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce). Transparent ceramic GYGAG(Ce), has a peak emission wavelength of 550 nm that is better matched to Silicon photodetectors than to standard PMTs. We are therefore developing a spectrometer based on pixelated GYGAG(Ce) on a Silicon photodiode array that can provide R(662 keV) = 3.6%. In comparison, with large 1-2 in3 size GYGAG(Ce) ceramics we obtain R(662 keV) = 4.6% with PMT readout. We find that ceramic GYGAG(Ce) of a given stoichiometric chemical composition can exhibit very different scintillation properties, depending on sintering conditions and post-anneal treatments. Among the characteristics of transparent ceramic garnet scintillators that can be controlled by fabrication conditions are: scintillation decay components and their amplitudes, intensity and duration of afterglow, thermoluminescence glow curve peak positions and amplitudes, integrated light yield, light yield non-proportionality - as measured in the Scintillator Light Yield Non-Proportionality Characterization Instrument (SLYNCI), and energy resolution for gamma spectroscopy. Garnet samples exhibiting a significant fraction of Cerium dopant in the tetravalent valence also exhibit: faster overall scintillation decay, very low afterglow, high light yield, but poor light yield proportionality and degraded energy resolution.

Use of ceramics in point-focus solar receivers

NASA Technical Reports Server (NTRS)

Smoak, R. H.; Kudirka, A. A.

1981-01-01

One of the research and development efforts in the Solar Thermal Energy Systems Project at the Jet Propulsion Laboratory has been focused on application of ceramic components for advanced point-focus solar receivers. The impetus for this effort is a need for high efficiency, low cost solar receivers which operate in a temperature regime where use of metal components is impractical. The current status of the work on evaluation of ceramic components at JPL and elsewhere is outlined and areas where lack of knowledge is currently slowing application of ceramics are discussed. Future developments of ceramic processing technology and reliability assurance methodology should open up applications for the point-focus solar concentrator system in fuels and chemicals production, in thermochemical energy transport and storage, in detoxification of hazardous materials and in high temperature process heat as well as for electric power generation.

Influence of valence state of copper ions on structural and spectroscopic properties of multi-component PbO-Al2O3-TeO2-GeO2-SiO2 glass ceramic system- a possible material for memory switching devices

NASA Astrophysics Data System (ADS)

Tirupataiah, Ch.; Narendrudu, T.; Suresh, S.; Srinivasa Rao, P.; Vinaya Teja, P. M.; Sambasiva Rao, M. V.; Chinna Ram, G.; Krishna Rao, D.

2017-11-01

Multi-component glass ceramics with composition 29PbO-5Al2O3-1TeO2 -10GeO2- (55-x) SiO2 doped with different concentrations of CuO (0 ≤ x ≤ 1.0 mol %) were synthesized by melt quenching technique and subsequent heat treatment. These glass ceramics were characterized by X-ray diffraction, scanning electron microscope, differential thermal analysis, optical absorption, electron paramagnetic resonance, Fourier transform infrared and Raman studies. The absorption spectra of these glass ceramics exhibited a broad absorption band in the range 650-950 nm which is ascribed to 2B1g → 2B2g octahedral transition of Cu2+ ions. A feeble band around 364 nm is also identified in the samples doped with CuO up to 0.6 mol% as being due to charge transfer between the two oxidation states Cu2+ and Cu+ of copper ions. The EPR spectrum recorded at room temperature exhibited a strong resonance signal at g⊥ = 2.072 and a shallow quadruplet at about gǁ = 2.401. FTIR and Raman spectra of the titled samples provide significant information about various structural units viz., silicate, germanate, PbO4, PbO6, AlO6, TeO4 and TeO3 that are present in these ceramic matrix. Analysis of the spectroscopic investigations reveals that with an increase in the concentration of CuO up to 0.6 mol% copper ions do exist in Cu2+ and Cu+ states and they act as modifiers and net work formers respectively. Therefore, glass ceramic sample contains 0.6 mol% of CuO is favorable for memory switching action.

Advanced Gas Turbine (AGT) Technology Development Project, ceramic component developments

NASA Technical Reports Server (NTRS)

Teneyck, M. O.; Macbeth, J. W.; Sweeting, T. B.

1987-01-01

The ceramic component technology development activity conducted by Standard Oil Engineered Materials Company while performing as a principal subcontractor to the Garrett Auxiliary Power Division for the Advanced Gas Turbine (AGT) Technology Development Project (NASA Contract DEN3-167) is summarized. The report covers the period October 1979 through July 1987, and includes information concerning ceramic technology work categorized as common and unique. The former pertains to ceramic development applicable to two parallel AGT projects established by NASA contracts DEN3-168 (AGT100) and DEN3-167 (AGT101), whereas the unique work solely pertains to Garrett directed activity under the latter contract. The AGT101 Technology Development Project is sponsored by DOE and administered by NASA-Lewis. Standard Oil directed its efforts toward the development of ceramic materials in the silicon-carbide family. Various shape forming and fabrication methods, and nondestructive evaluation techniques were explored to produce the static structural components for the ceramic engine. This permitted engine testing to proceed without program slippage.

Ceramic combustor mounting

DOEpatents

Hoffman, Melvin G.; Janneck, Frank W.

1982-01-01

A combustor for a gas turbine engine includes a metal engine block including a wall portion defining a housing for a combustor having ceramic liner components. A ceramic outlet duct is supported by a compliant seal on the metal block and a reaction chamber liner is stacked thereon and partly closed at one end by a ceramic bypass swirl plate which is spring loaded by a plurality of circumferentially spaced, spring loaded guide rods and wherein each of the guide rods has one end thereof directed exteriorly of a metal cover plate on the engine block to react against externally located biasing springs cooled by ambient air and wherein the rod spring support arrangement maintains the stacked ceramic components together so that a normal force is maintained on the seal between the outlet duct and the engine block under all operating conditions. The support arrangement also is operative to accommodate a substantial difference in thermal expansion between the ceramic liner components of the combustor and the metal material of the engine block.

Ceramic component for electrodes

DOEpatents

Marchant, David D.

1979-01-01

A ceramic component suitable for preparing MHD generator electrodes consists of HfO.sub.2 and sufficient Tb.sub.4 O.sub.7 to stabilize at least 60 volume percent of the HfO.sub.2 into the cubic structure. The ceramic component may also contain a small amount of PrO.sub.2, Yb.sub.2 O.sub.3 or a mixture of both to improve stability and electronic conductivity of the electrode. The component is highly resistant to corrosion by molten potassium seed and molten coal slag in the MHD fluid and exhibits both ionic and electronic conductivity.

Coating system to permit direct brazing of ceramics

DOEpatents

Cadden, Charles H.; Hosking, F. Michael

2003-01-01

This invention relates to a method for preparing the surface of a ceramic component that enables direct brazing using a non-active braze alloy. The present invention also relates to a method for directly brazing a ceramic component to a ceramic or metal member using this method of surface preparation, and to articles produced by using this brazing method. The ceramic can be high purity alumina. The method comprises applying a first coating of a silicon-bearing oxide material (e.g. silicon dioxide or mullite (3Al.sub.2 O.sub.3.2SiO.sub.2) to the ceramic. Next, a thin coating of active metal (e.g. Ti or V) is applied. Finally, a thicker coating of a non-active metal (e.g. Au or Cu) is applied. The coatings can be applied by physical vapor deposition (PVD). Alternatively, the active and non-active metals can be co-deposited (e.g. by sputtering a target made of mullite). After all of the coatings have been applied, the ceramic can be fired at a high temperature in a non-oxidizing environment to promote diffusion, and to enhance bonding of the coatings to the substrate. After firing, the metallized ceramic component can be brazed to other components using a conventional non-active braze alloy. Alternatively, the firing and brazing steps can be combined into a single step. This process can replace the need to perform a "moly-manganese" metallization step.

Fabrication of High Temperature Cermet Materials for Nuclear Thermal Propulsion

NASA Technical Reports Server (NTRS)

Hickman, Robert; Panda, Binayak; Shah, Sandeep

2005-01-01

Processing techniques are being developed to fabricate refractory metal and ceramic cermet materials for Nuclear Thermal Propulsion (NTP). Significant advances have been made in the area of high-temperature cermet fuel processing since RoverNERVA. Cermet materials offer several advantages such as retention of fission products and fuels, thermal shock resistance, hydrogen compatibility, high conductivity, and high strength. Recent NASA h d e d research has demonstrated the net shape fabrication of W-Re-HfC and other refractory metal and ceramic components that are similar to UN/W-Re cermet fuels. This effort is focused on basic research and characterization to identify the most promising compositions and processing techniques. A particular emphasis is being placed on low cost processes to fabricate near net shape parts of practical size. Several processing methods including Vacuum Plasma Spray (VPS) and conventional PM processes are being evaluated to fabricate material property samples and components. Surrogate W-Re/ZrN cermet fuel materials are being used to develop processing techniques for both coated and uncoated ceramic particles. After process optimization, depleted uranium-based cermets will be fabricated and tested to evaluate mechanical, thermal, and hot H2 erosion properties. This paper provides details on the current results of the project.

Award-Winning CARES/Life Ceramics Durability Evaluation Software Is Making Advanced Technology Accessible

NASA Technical Reports Server (NTRS)

1997-01-01

Products made from advanced ceramics show great promise for revolutionizing aerospace and terrestrial propulsion and power generation. However, ceramic components are difficult to design because brittle materials in general have widely varying strength values. The CARES/Life software developed at the NASA Lewis Research Center eases this by providing a tool that uses probabilistic reliability analysis techniques to optimize the design and manufacture of brittle material components. CARES/Life is an integrated package that predicts the probability of a monolithic ceramic component's failure as a function of its time in service. It couples commercial finite element programs--which resolve a component's temperature and stress distribution - with reliability evaluation and fracture mechanics routines for modeling strength - limiting defects. These routines are based on calculations of the probabilistic nature of the brittle material's strength.

Damage Characterization of EBC-SiCSiC Ceramic Matrix Composites Under Imposed Thermal Gradient Testing

NASA Technical Reports Server (NTRS)

Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

2014-01-01

Due to their high temperature capabilities, Ceramic Matrix Composite (CMC) components are being developed for use in hot-section aerospace engine applications. Harsh engine environments have led to the development of Environmental Barrier Coatings (EBCs) for silicon-based CMCs to further increase thermal and environmental capabilities. This study aims at understanding the damage mechanisms associated with these materials under simulated operating conditions. A high heat-flux laser testing rig capable of imposing large through-thickness thermal gradients by means of controlled laser beam heating and back-side air cooling is used. Tests are performed on uncoated composites, as well as CMC substrates that have been coated with state-of-the-art ceramic EBC systems. Results show that the use of the EBCs may help increase temperature capability and creep resistance by reducing the effects of stressed oxidation and environmental degradation. Also, the ability of electrical resistance (ER) and acoustic emission (AE) measurements to monitor material condition and damage state during high temperature testing is shown; suggesting their usefulness as a valuable health monitoring technique. Micromechanics models are used to describe the localized stress state of the composite system, which is utilized along with ER modeling concepts to develop an electromechanical model capable of characterizing material behavior.

[Spectroscopic Research on Slag Nanocrystal Glass Ceramics Containing Rare Earth Elements].

PubMed

Ouyang, Shun-li; Li, Bao-wei; Zhang, Xue-feng; Jia, Xiao-lin; Zhao, Ming; Deng, Lei-bo

2015-08-01

The research group prepared the high-performance slag nanocrystal glass ceramics by utilizing the valuable elements of the wastes in the Chinese Bayan Obo which are characterized by their symbiotic or associated existence. In this paper, inductively coupled plasma emission spectroscopy (ICP), X-ray diffraction (XRD), Raman spectroscopy (Raman) and scanning electron microscopy (SEM) are all used in the depth analysis for the composition and structure of the samples. The experiment results of ICP, XRD and SEM showed that the principal crystalline phase of the slag nanocrystal glass ceramics containing rare earth elements is diopside, its grain size ranges from 45 to 100 nm, the elements showed in the SEM scan are basically in consistent with the component analysis of ICP. Raman analysis indicated that its amorphous phase is a three-dimensional network structure composed by the structural unit of silicon-oxy tetrahedron with different non-bridging oxygen bonds. According to the further analysis, we found that the rare earth microelement has significant effect on the network structure. Compared the nanocrystal slag glass ceramic with the glass ceramics of similar ingredients, we found that generally, the Raman band wavenumber for the former is lower than the later. The composition difference between the glass ceramics and the slag nanocrystal with the similar ingredients mainly lies on the rare earth elements and other trace elements. Therefore, we think that the rare earth elements and other trace elements remains in the slag nanocrystal glass ceramics have a significant effect on the network structure of amorphous phase. The research method of this study provides an approach for the relationship among the composition, structure and performance of the glass ceramics.

Nondestructive Characterization Techniques Used for Ceramic Matrix Composite Life Determination

NASA Technical Reports Server (NTRS)

Effinger, Michael; Koenig, John; Ellingson, Bill; Spohnholtz, Todd

2000-01-01

Recent results indicate that the specific damping capacity and resonant frequency measurements taken periodically during a component's lifetime is able to quantify the mechanical fatigue of CMCS. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction, a review of the C/SiC blisk damping data, and how changes in the specific damping capacity & ultrasonic elastic modulus data have established the concept as a possibility.

Ceramic composites for rocket engine turbines

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.

1991-01-01

The use of ceramic materials in the hot section of the fuel turbopump of advanced reusable rocket engines promises increased performance and payload capability, improved component life and economics, and greater design flexibility. Severe thermal transients present during operation of the Space Shuttle Main Engine (SSME), push metallic components to the limit of their capabilities. Future engine requirements might be even more severe. In phase one of this two-phase program, performance benefits were quantified and continuous fiber reinforced ceramic matrix composite components demonstrated a potential to survive the hostile environment of an advanced rocket engine turbopump.

Ceramic composites for rocket engine turbines

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.

1991-01-01

The use of ceramic materials in the hot section of the fuel turbopump of advanced reusable rocket engines promises increased performance and payload capability, improved component life and economics, and greater design flexibility. Severe thermal transients present during operation of the Space Shuttle Main Engine (SSME), push metallic components to the limit of their capabilities. Future engine requirements might be even more severe. In phase one of this two-phase program, performance benefits were quantified and continuous fiber reinforced ceramic matrix composite components demonstrated a potential to survive the hostile environment of an advaced rocket engine turbopump.

Ceramic technology for automotive turbines

NASA Technical Reports Server (NTRS)

Mclean, A. F.

1982-01-01

The paper presents an update on ceramic technology for automotive turbines. Progress in research and development of improved ceramics is reviewed, including approaches for assessing time-dependent strength characteristics. Processes for making shapes are discussed, and the design and testing of selected ceramic turbine components are reviewed.

AGT 100 automotive gas turbine system development

NASA Technical Reports Server (NTRS)

Helms, H. E. G.

1982-01-01

General Motors is developing an automotive gas turbine system that can be an alternate powerplant for future automobiles. Work sponsored by DOE and administered by NASA Lewis Research Center is emphasizing small component aerodynamics and high-temperature structural ceramics. Reliability requirements of the AGT 100 turbine system include chemical and structural ceramic component stability in the gas turbine environment. The power train system, its configuration and schedule are presented, and its performance tested. The aerodynamic component development is reviewed with discussions on the compressor, turbine, regenerator, interturbine duct and scroll, and combustor. Ceramic component development is also reviewed, and production cost and required capital investment are taken into consideration.

Characterization and Glass Formation of JSC-1 Lunar and Martian Soil Simulants

NASA Technical Reports Server (NTRS)

Sen, Subhayu

2008-01-01

The space exploration mission of NASA requires long duration presence of human being beyond the low earth orbit (LEO), especially on Moon and Mars. Developing a human habitat or colony on these planets would require a diverse range of materials, whose applications would range from structural foundations, (human) life support, (electric) power generation to components for scientific instrumentation. A reasonable and cost-effective approach for fabricating the materials needed for establishing a self-sufficient human outpost would be to primarily use local (in situ) resources on these planets. Since ancient times, glass and ceramics have been playing a vital role on human civilization. A long term project on studying the feasibility of developing glass and ceramic materials using Lunar and Martian soil simulants (JSC-1) as developed by Johnson Space Center has been undertaken. The first step in this on-going project requires developing a data base on results that fully characterize the simulants to be used for further investigations. The present paper reports characterization data of both JSC-1 Lunar and JSC Mars-1 simulants obtained up to this time via x-ray diffraction analysis, scanning electron microscopy, thermal analysis (DTA, TGA) and chemical analysis. The critical cooling rate for glass formation for the melts of the simulants was also measured in order to quantitatively assess the glass forming tendency of these melts. The importance of the glasses and ceramics developed using in-situ resources for constructing human habitats on Moon or Mars is discussed.

Tribological performance of the biological components of synovial fluid in artificial joint implants

NASA Astrophysics Data System (ADS)

Ghosh, Subir; Choudhury, Dipankar; Roy, Taposh; Moradi, Ali; Masjuki, H. H.; Pingguan-Murphy, Belinda

2015-08-01

The concentration of biological components of synovial fluid (such as albumin, globulin, hyaluronic acid, and lubricin) varies between healthy persons and osteoarthritis (OA) patients. The aim of the present study is to compare the effects of such variation on tribological performance in a simulated hip joint model. The study was carried out experimentally by utilizing a pin-on-disk simulator on ceramic-on-ceramic (CoC) and ceramic-on-polyethylene (CoP) hip joint implants. The experimental results show that both friction and wear of artificial joints fluctuate with the concentration level of biological components. Moreover, the performance also varies between material combinations. Wear debris sizes and shapes produced by ceramic and polyethylene were diverse. We conclude that the biological components of synovial fluid and their concentrations should be considered in order to select an artificial hip joint to best suit that patient.

Luminescence and scintillation properties of BaF2sbnd Ce transparent ceramic

NASA Astrophysics Data System (ADS)

Luo, Junming; Sahi, Sunil; Groza, Michael; Wang, Zhiqiang; Ma, Lun; Chen, Wei; Burger, Arnold; Kenarangui, Rasool; Sham, Tsun-Kong; Selim, Farida A.

2016-08-01

Cerium doped Barium Fluoride (BaF2sbnd Ce) transparent ceramic was fabricated and its luminescence and scintillation properties were studied. The photoluminescence shows the emission peaks at 310 nm and 323 nm and is related to the 5d-4f transitions in Ce3+ ion. Photo peak at 511 keV and 1274 keV were obtained with BaF2sbnd Ce transparent ceramic for Na-22 radioisotopes. Energy resolution of 13.5% at 662 keV is calculated for the BaF2sbnd Ce transparent ceramic. Light yield of 5100 photons/MeV was recorded for BaF2sbnd Ce(0.2%) ceramic and is comparable to its single crystal counterpart. Scintillation decay time measurements shows fast component of 58 ns and a relatively slow component of 434 ns under 662 keV gamma excitation. The slower component in BaF2sbnd Ce(0.2%) ceramic is about 200 ns faster than the STE emission in BaF2 host and is associated with the dipole-dipole energy transfer from the host matrix to Ce3+ luminescence center.

Assessment of exposures and potential risks to the US adult population from wear (attrition and abrasion) of gold and ceramic dental restorations.

PubMed

Richardson, G Mark; Clemow, Scott R; Peters, Rachel E; James, Kyle J; Siciliano, Steven D

2016-01-01

Little has been published on the chemical exposures and risks of dental restorative materials other than from dental amalgam and composite resins. Here we provide the first exposure and risk assessment for gold (Au) alloy and ceramic restorative materials. Based on the 2001-2004 US National Health and Nutrition Examination Survey (NHANES), we assessed the exposure of US adults to the components of Au alloy and ceramic dental restorations owing to dental material wear. Silver (Ag) is the most problematic component of Au alloy restorations, owing to a combination of toxicity and proportional composition. It was estimated that adults could possess an average of four tooth surfaces restored with Au alloy before exceeding, on average, the reference exposure level (REL) for Ag. Lithium (Li) is the most problematic component of dental ceramics. It was estimated that adults could possess an average of 15 tooth surfaces restored with ceramics before exceeding the REL for Li. Relative risks of chemical exposures from dental materials decrease in the following order: Amalgam>Au alloys>ceramics>composite resins.

Advanced Environmental Barrier Coatings Developed for SiC/SiC Composite Vanes

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Fox, Dennis S.; Eldridge, Jeffrey I.; Zhu, Dongming; Bansal, Narottam P.; Miller, Robert A.

2003-01-01

Ceramic components exhibit superior high-temperature strength and durability over conventional component materials in use today, signifying the potential to revolutionize gas turbine engine component technology. Silicon-carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC/SiC CMCs) are prime candidates for the ceramic hotsection components of next-generation gas turbine engines. A key barrier to the realization of SiC/SiC CMC hot-section components is the environmental degradation of SiC/SiC CMCs in combustion environments. This is in the form of surface recession due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is a logical approach to achieve protection and long-term durability.

Ceramic Technology for Advanced Heat Engines Project

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

Not Available

1989-08-01

The Ceramic Technology for Advanced Heat Engines Project was developed by the Department of Energy's Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Advanced Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional researchmore » is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially.« less

Composite turbine bucket assembly

DOEpatents

Liotta, Gary Charles; Garcia-Crespo, Andres

2014-05-20

A composite turbine blade assembly includes a ceramic blade including an airfoil portion, a shank portion and an attachment portion; and a transition assembly adapted to attach the ceramic blade to a turbine disk or rotor, the transition assembly including first and second transition components clamped together, trapping said ceramic airfoil therebetween. Interior surfaces of the first and second transition portions are formed to mate with the shank portion and the attachment portion of the ceramic blade, and exterior surfaces of said first and second transition components are formed to include an attachment feature enabling the transition assembly to be attached to the turbine rotor or disk.

A 37-mm Ceramic Gun Nozzle Stress Analysis

DTIC Science & Technology

2006-05-01

Figures iv List of Tables iv 1 . Introduction 1 2. Ceramic Nozzle Structure and Materials 1 3. Sequentially-Coupled and Fully-Coupled Thermal Stress...FEM Analysis 1 4. Ceramic Nozzle Thermal Stress Response 4 5. Ceramic Nozzle Dynamic FEM 7 6. Ceramic Nozzle Dynamic Responses and Discussions 8 7...candidate ceramics and the test fixture model components are listed in table 1 . 3. Sequentially-Coupled and Fully-Coupled Thermal Stress FEM Analysis

Fracture mechanics concepts in reliability analysis of monolithic ceramics

NASA Technical Reports Server (NTRS)

Manderscheid, Jane M.; Gyekenyesi, John P.

1987-01-01

Basic design concepts for high-performance, monolithic ceramic structural components are addressed. The design of brittle ceramics differs from that of ductile metals because of the inability of ceramic materials to redistribute high local stresses caused by inherent flaws. Random flaw size and orientation requires that a probabilistic analysis be performed in order to determine component reliability. The current trend in probabilistic analysis is to combine linear elastic fracture mechanics concepts with the two parameter Weibull distribution function to predict component reliability under multiaxial stress states. Nondestructive evaluation supports this analytical effort by supplying data during verification testing. It can also help to determine statistical parameters which describe the material strength variation, in particular the material threshold strength (the third Weibull parameter), which in the past was often taken as zero for simplicity.

PREFACE: Symposium 1: Advanced Structure Analysis and Characterization of Ceramic Materials

NASA Astrophysics Data System (ADS)

Yashima, Masatomo

2011-05-01

Preface to Symposium 1 (Advanced Structure Analysis and Characterization of Ceramic Materials) of the International Congress of Ceramics III, held 14-18 November 2010 in Osaka, Japan Remarkable developments have been made recently in the structural analysis and characterization of inorganic crystalline and amorphous materials, such as x-ray, neutron, synchrotron and electron diffraction, x-ray/neutron scattering, IR/Raman scattering, NMR, XAFS, first-principle calculations, computer simulations, Rietveld analysis, the maximum-entropy method, in situ measurements at high temperatures/pressures and electron/nuclear density analysis. These techniques enable scientists to study not only static and long-range periodic structures but also dynamic and short-/intermediate-range structures. Multi-scale characterization from the electron to micrometer levels is becoming increasingly important as a means of understanding phenomena at the interfaces, grain boundaries and surfaces of ceramic materials. This symposium has discussed the structures and structure/property relationships of various ceramic materials (electro, magnetic and optical ceramics; energy and environment related ceramics; bio-ceramics; ceramics for reliability secure society; traditional ceramics) through 38 oral presentations including 8 invited lectures and 49 posters. Best poster awards were given to six excellent poster presentations (Y-C Chen, Tokyo Institute of Technology; C-Y Chung, Tohoku University; T Stawski, University of Twente; Y Hirano, Nagoya Institute of Technology; B Bittova, Charles University Prague; Y Onodera, Kyoto University). I have enjoyed working with my friends in the ICC3 conference. I would like to express special thanks to other organizers: Professor Scott T Misture, Alfred University, USA, Professor Xiaolong Chen, Institute of Physics, CAS, China, Professor Takashi Ida, Nagoya Institute of Technology, Japan, Professor Isao Tanaka, Kyoto University, Japan. I also acknowledge the invited speakers, all the participants and organizing committee of the ICC3. I am pleased to publish the Proceedings of the Symposium 1 of ICC3. I hope that the papers contained in these Proceedings will prove helpful to Professors, researchers and students in improving the fields of Structure Analysis and Characterization of Ceramic Materials. Masatomo Yashima April 2011 Department of Chemistry and Materials Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, Japan

A Step-by-Step Conservative Approach for CAD-CAM Laminate Veneers

PubMed Central

Henríquez Gutiérrez, Ismael; Guzmán Marusic, Álvaro; Báez Rosales, Abelardo; Tisi Lanchares, José Pablo

2017-01-01

The use of CAD/CAM technology has allowed the fabrication of ceramic restorations efficiently and with predictable results. Lithium disilicate is a type of glass ceramic material that can be used for the elaboration of laminate veneers, being monolithic restorations which require characterization through a covering ceramic in order to achieve acceptable esthetic results. The next case report shows a predictable clinical protocol for the rehabilitation of the anterior teeth through the preparation of CAD/CAM veneers (e.max CAD, Ivoclar Vivadent, Liechtenstein) which have been characterized by a nanofluorapatite ceramic (e.max Ceram, Ivoclar Vivadent, Liechtenstein) through the layering technique. PMID:28884029

Ballistic Performance of Porous-Ceramic, Thermal-Protection-Systems

NASA Technical Reports Server (NTRS)

Christiansen, E. L.; Davis, B. A.; Miller, J. E.; Bohl, W. E.; Foreman, C. D.

2009-01-01

Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Space Shuttle and are currently being proposed for the next generation of manned spacecraft, Orion. These materials insulate the structural components of a spacecraft against the intense thermal environments of atmospheric reentry. Furthermore, these materials are also highly exposed to space environmental hazards like meteoroid and orbital debris impacts. This paper discusses recent impact testing up to 9 km/s, and the findings of the influence of material equation-of-state on the simulation of the impact event to characterize the ballistic performance of these materials. These results will be compared with heritage models1 for these materials developed from testing at lower velocities. Assessments of predicted spacecraft risk based upon these tests and simulations will also be discussed.

Studies of Ultra High Temperature Ceramic Composite Components: Synthesis and Characterization of HfOxCy and Si Oxidation in Atomic Oxygen Containing Environments

DTIC Science & Technology

2008-08-01

Andrea Hafeman and Dr Scott Guelcher for the use of the SDT analysis software. I would like to thank my committee members: Dr Clare McCabe, Dr Sharon...76 4.2: Thermogravimetric curves obtained during oxidation of hafnium...77 4.3: The thermogravimetric curves for hafnia and hafnium oxycarbide (28 mTorr) oxidized at 600°C

Silicon carbide ceramic production

NASA Technical Reports Server (NTRS)

Suzuki, K.; Shinohara, N.

1984-01-01

A method to produce sintered silicon carbide ceramics in which powdery carbonaceous components with a dispersant are mixed with silicon carbide powder, shaped as required with or without drying, and fired in nonoxidation atmosphere is described. Carbon black is used as the carbonaceous component.

Ceramic Parts for Turbines

NASA Technical Reports Server (NTRS)

Jones, R. D.; Carpenter, Harry W.; Tellier, Jim; Rollins, Clark; Stormo, Jerry

1987-01-01

Abilities of ceramics to serve as turbine blades, stator vanes, and other elements in hot-gas flow of rocket engines discussed in report. Ceramics prime candidates, because of resistance to heat, low density, and tolerance of hostile environments. Ceramics considered in report are silicon nitride, silicon carbide, and new generation of such ceramic composites as transformation-toughened zirconia and alumina and particulate- or whisker-reinforced matrices. Report predicts properly designed ceramic components viable in advanced high-temperature rocket engines and recommends future work.

Nondestructive evaluation techniques for high-temperature ceramic components. Quarterly report, October--December 1977. [Silicon carbide

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

Not Available

1978-02-01

The overall objective of this program is to assess and develop nondestructive evaluation procedures for high-temperature ceramics. The program is currently evaluating ceramic heat-exchanger tubing. Ceramic heat exchangers would be useful, for example, in coal-fired Brayton conversion or waste heat-recovery systems. The use of ceramic heat exchangers will allow working fluids to reach temperatures up to 1230/sup 0/C, and, with further materials development, possibly 1650/sup 0/C. If superalloys were employed, working fluids would be limited to approximately 800/sup 0/C. The use of working fluids at higher temperatures would result in more efficient systems. Furthermore, ceramic components are lighter than metallicmore » ones and are made from less costly and more abundant elements. In addition, ceramic heat exchangers would be more resistant to corrosion. In the current NDE effort, several acoustic, optical, and radiographic techniques are being examined for their effectiveness in testing silicon carbide tubing. Some results employing dye-enhanced radiography are discussed.« less

Wedge edge ceramic combustor tile

DOEpatents

Shaffer, J.E.; Holsapple, A.C.

1997-06-10

A multipiece combustor has a portion thereof being made of a plurality of ceramic segments. Each of the plurality of ceramic segments have an outer surface and an inner surface. Each of the plurality of ceramic segments have a generally cylindrical configuration and including a plurality of joints. The joints define joint portions, a first portion defining a surface being skewed to the outer surface and the inner surface. The joint portions have a second portion defining a surface being skewed to the outer surface and the inner surface. The joint portions further include a shoulder formed intermediate the first portion and the second portion. The joints provide a sealing interlocking joint between corresponding ones of the plurality of ceramic segments. Thus, the multipiece combustor having the plurality of ceramic segment with the plurality of joints reduces the physical size of the individual components and the degradation of the surface of the ceramic components in a tensile stress zone is generally eliminated reducing the possibility of catastrophic failures. 7 figs.

Wedge edge ceramic combustor tile

DOEpatents

Shaffer, James E.; Holsapple, Allan C.

1997-01-01

A multipiece combustor has a portion thereof being made of a plurality of ceramic segments. Each of the plurality of ceramic segments have an outer surface and an inner surface. Each of the plurality of ceramic segments have a generally cylindrical configuration and including a plurality of joints. The joints define joint portions, a first portion defining a surface being skewed to the outer surface and the inner surface. The joint portions have a second portion defining a surface being skewed to the outer surface and the inner surface. The joint portions further include a shoulder formed intermediate the first portion and the second portion. The joints provide a sealing interlocking joint between corresponding ones of the plurality of ceramic segments. Thus, the multipiece combustor having the plurality of ceramic segment with the plurality of joints reduces the physical size of the individual components and the degradation of the surface of the ceramic components in a tensile stress zone is generally eliminated reducing the possibility of catastrophic failures.

Biomechanical behavior of a cemented ceramic knee replacement under worst case scenarios

NASA Astrophysics Data System (ADS)

Kluess, D.; Mittelmeier, W.; Bader, R.

2009-12-01

In connection with technological advances in the manufacturing of medical ceramics, a newly developed ceramic femoral component was introduced in total knee arthroplasty (TKA). The motivation to consider ceramics in TKA is based on the allergological and tribological benefits as proven in total hip arthroplasty. Owing to the brittleness and reduced fracture toughness of ceramic materials, the biomechanical performance has to be examined intensely. Apart from standard testing, we calculated the implant performance under different worst case scenarios including malposition, bone defects and stumbling. A finite-element-model was developed to calculate the implant performance in situ. The worst case conditions revealed principal stresses 12.6 times higher during stumbling than during normal gait. Nevertheless, none of the calculated principal stress amounts were above the critical strength of the ceramic material used. The analysis of malposition showed the necessity of exact alignment of the implant components.

Biomechanical behavior of a cemented ceramic knee replacement under worst case scenarios

NASA Astrophysics Data System (ADS)

Kluess, D.; Mittelmeier, W.; Bader, R.

2010-03-01

In connection with technological advances in the manufacturing of medical ceramics, a newly developed ceramic femoral component was introduced in total knee arthroplasty (TKA). The motivation to consider ceramics in TKA is based on the allergological and tribological benefits as proven in total hip arthroplasty. Owing to the brittleness and reduced fracture toughness of ceramic materials, the biomechanical performance has to be examined intensely. Apart from standard testing, we calculated the implant performance under different worst case scenarios including malposition, bone defects and stumbling. A finite-element-model was developed to calculate the implant performance in situ. The worst case conditions revealed principal stresses 12.6 times higher during stumbling than during normal gait. Nevertheless, none of the calculated principal stress amounts were above the critical strength of the ceramic material used. The analysis of malposition showed the necessity of exact alignment of the implant components.

Ceramic material suitable for repair of a space vehicle component in a microgravity and vacuum environment, method of making same, and method of repairing a space vehicle component

NASA Technical Reports Server (NTRS)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2009-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium diboride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Characterization of glass-infiltrated alumina-based ceramics

PubMed Central

Bona, Alvaro Della; Mecholsky, John J; Barrett, Allyson A; Griggs, Jason A

2010-01-01

Objective characterize the microstructure, composition, and important properties of glass-infiltrated alumina-based ceramics similar to the In-Ceram system. Methods Materials used were: IA- In-Ceram Alumina (Vita); IAE- IA electrophoretically deposited (Vita); AEM- IA using a vacuum driven method (Vita); VC- Vitro-Ceram (Angelus); TC- Turkom-Cera (Turkom-Ceramic); CC- Ceramcap (Foto-Ceram); and AG- Alglass (EDG). Ceramic specimens were fabricated following manufacturers’ instructions and ISO6872 standard and polished successively through 1μm alumina abrasive. Semi-quantitative and qualitative analyses were performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and stereology (Vv). The elastic modulus (E) and Poisson’s ratio (ν) were determined using time-of-flight data measured in an ultrasonic pulser/receiver and the density (ρ) was determined using a helium pycnometer. Vicker’s indentation was used to calculate hardness (H). Bar specimens (25×4×1.2mm3) were loaded in three-point bending to fracture using a universal testing machine with cross-head speed of 1mm/min. Flexural strength (σ3P) was calculated and statistically analyzed using ANOVA, Tukey (α=0.05) and Weibull (m= modulus, σ0= characteristic strength). Results SEM and EDS analyses revealed similar microstructure for all ceramics, except for a lead-based matrix in CC and a zirconia phase in VC. TC, AG and CC showed significantly lower mean σ3P values than the other ceramics (p 0.05). AEM showed the greatest m (16). Conclusion Despite few differences in microstructure and composition, the IA, IAE, AEM and VC ceramics have similar properties. Significance The glass-infiltrated alumina-based ceramics from different manufacturers presented distinct characteristics. It is necessary to characterize new commercially available materials to understand their properties. PMID:18692231

Investigations of subcritical crack propagation of the Empress 2 all-ceramic system.

PubMed

Mitov, Gergo; Lohbauer, Ulrich; Rabbo, Mohammad Abed; Petschelt, Anselm; Pospiech, Peter

2008-02-01

The mechanical properties and slow crack propapagation of the all-porcelain system Empress 2 (Ivoclar Vivadent, Schaan, Liechtenstein) with its framework compound Empress 2 and the veneering compounds "Empress 2 and Eris were examined. For all materials, the fracture strength, Weibull parameter and elastic moduli were experimentally determined in a four-point-bending test. For the components of the Empress 2 system, the fracture toughness K(IC) was determined, and the crack propagation parameters n and A were determined in a dynamic fatigue method. Using these data, life data analysis was performed and lifetime diagrams were produced. The development of strength under static fatigue conditions was calculated for a period of 5 years. The newly developed veneering ceramic Eris showed a higher fracture strength (sigma(0)=66.1 MPa) at a failure probability of P(F)=63.2%, and crack growth parameters (n=12.9) compared to the veneering ceramic Empress 2 (sigma(0)=60.3 MPa). For Empress 2 veneer the crack propagation parameter n could only be estimated (n=9.5). This is reflected in the prognosis of long-term resistance presented in the SPT diagrams. For all materials investigated, the Weibull parameter m values (Empress 2 framework m=4.6; Empress 2 veneer m=7.9; Eris m=6.9) were much lower than the minimum demanded by the literature (m=15). The initial fracture strength value alone is not sufficient to characterize the mechanical resistance of ceramic materials, since their stressability is time-dependent. Knowledge about the crack propagation parameters n and A are of great importance when preclinically predicting the clinical suitability of dental ceramic materials. The use of SPT diagrams for lifetime calculation of ceramic materials is a valuable method for comparing different ceramics.

Sol-gel applications for ceramic membrane preparation

NASA Astrophysics Data System (ADS)

Erdem, I.

2017-02-01

Ceramic membranes possessing superior properties compared to polymeric membranes are more durable under severe working conditions and therefore their service life is longer. The ceramic membranes are composed of some layers. The support is the layer composed of coarser ceramic structure and responsible for mechanical durability under filtration pressure and it is prepared by consolidation of ceramic powders. The top layer is composed of a finer ceramic micro-structure mainly responsible for the separation of components present in the fluid to be filtered and sol-gel method is a versatile tool to prepare such a tailor-made ceramic filtration structure with finer pores. Depending on the type of filtration (e.g. micro-filtration, ultra-filtration, nano-filtration) aiming separation of components with different sizes, sols with different particulate sizes should be prepared and consolidated with varying precursors and preparation conditions. The coating of sol on the support layer and heat treatment application to have a stable ceramic micro-structure are also important steps determining the final properties of the top layer. Sol-gel method with various controllable parameters (e.g. precursor type, sol formation kinetics, heat treatment conditions) is a practical tool for the preparation of top layers of ceramic composite membranes with desired physicochemical properties.

Ceramic applications in turbine engines

NASA Technical Reports Server (NTRS)

Byrd, J. A.; Janovicz, M. A.; Thrasher, S. R.

1981-01-01

Development testing activities on the 1900 F-configuration ceramic parts were completed, 2070 F-configuration ceramic component rig and engine testing was initiated, and the conceptual design for the 2265 F-configuration engine was identified. Fabrication of the 2070 F-configuration ceramic parts continued, along with burner rig development testing of the 2070 F-configuration metal combustor in preparation for 1132 C (2070 F) qualification test conditions. Shakedown testing of the hot engine simulator (HES) rig was also completed in preparation for testing of a spin rig-qualified ceramic-bladed rotor assembly at 1132 C (2070 F) test conditions. Concurrently, ceramics from new sources and alternate materials continued to be evaluated, and fabrication of 2070 F-configuration ceramic component from these new sources continued. Cold spin testing of the critical 2070 F-configuration blade continued in the spin test rig to qualify a set of ceramic blades at 117% engine speed for the gasifier turbine rotor. Rig testing of the ceramic-bladed gasifier turbine rotor assembly at 108% engine speed was also performed, which resulted in the failure of one blade. The new three-piece hot seal with the nickel oxide/calcium fluoride wearface composition was qualified in the regenerator rig and introduced to engine operation wiwth marginal success.

Development of manufacturing processes: improved technology for ceramic engine components. Monthly report, August 1977

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

Craig, D.F.; Taylor, A.J.; Weber, G.W.

Progress is described in a research program to develop advanced tooling concepts, processing techniques, and related technology for the economical high-volume manufacture of ceramic engine components. Because of the success of the initial fabrication effort for hot pressing fully dense ceramic turbine blades to shape and/or contour, the effort has been extended to include the fabrication of more complex shapes and the evaluation of alternative pressure-assisted, high-temperature, consolidation methods.

Preliminary Investigation of a Gas Turbine with Sillimanite Ceramic Rotor Blades

DTIC Science & Technology

1947-07-01

1399 s PRELIMINARY INVESTIGATION OF A GAS TUR81NE WITH SILLIMMWTE CEIUUMIC ROTOR BIXDES By Frederick J. Hartwig, Bob W. Sheflin and Robert J. Jones...SILLIWITE CERAMIC ROTOR BLADES 13yFrederick J. Hartwig, Bob W. ShefMm and Robert J. Jones SUMMARY A gas turbine with rotor blades of a sillimanite...to rotating turbine components. Invostlgations have shown that advantageous appli- cations of ceramics to stressed components of gas turbines can be

Surfaces and interfaces of glass and ceramics; Proceedings of the International Symposium on Special Topics in Ceramics, Alfred University, Alfred, N.Y., August 27-29, 1973

NASA Technical Reports Server (NTRS)

Frechette, V. D. (Editor); Lacourse, W. C.; Burdick, V. L.

1974-01-01

The characterization of surfaces and interfaces is considered along with the infrared spectra of several N-containing compounds absorbed on montmorillonites, applications of surface characterization techniques to glasses, the observation of electronic spectra in glass and ceramic surfaces, a method for determining the preferred orientation of crystallites normal to a surface, and the friction and wear behavior of glasses and ceramics. Attention is given to the wear behavior of cast surface composites, an experimental investigation of the dynamic and thermal characteristics of the ceramic stock removal process, a dynamic elastic model of ceramic stock removal, and the structure and properties of solid surfaces. Individual items are announced in this issue.

Advanced diesel engine component development program, tasks 4-14

NASA Astrophysics Data System (ADS)

Kaushal, Tony S.; Weber, Karen E.

1994-11-01

This report summarizes the Advanced Diesel Engine Component Development (ADECD) Program to develop and demonstrate critical technology needed to advance the heavy-duty low heat rejection engine concept. Major development activities reported are the design, analysis, and fabrication of monolithic ceramic components; vapor phase and solid film lubrication; electrohydraulic valve actuation; and high pressure common rail injection. An advanced single cylinder test bed was fabricated as a laboratory tool in studying these advanced technologies. This test bed simulates the reciprocator for a system having no cooling system, turbo compounding, Rankine bottoming cycle, common rail injection, and variable valve actuation to achieve fuel consumption of 160 g/kW-hr (.26 lb/hp-hr). The advanced concepts were successfully integrated into the test engine. All ceramic components met their functional and reliability requirements. The firedeck, cast-in-place ports, valves, valve guides, piston cap, and piston ring were made from silicon nitride. Breakthroughs required to implement a 'ceramic' engine included the fabrication of air-gap cylinder heads, elimination of compression gaskets, machining of ceramic valve seats within the ceramic firedeck, fabrication of cast-in-place ceramic port liners, implementation of vapor phase lubrication, and elimination of the engine coolant system. Silicon nitride valves were successfully developed to meet several production abuse test requirements and incorporated into the test bed with a ceramic valve guide and solid film lubrication. The ADECD cylinder head features ceramic port shields to increase insulation and exhaust energy recovery. The combustion chamber includes a ceramic firedeck and piston cap. The tribological challenge posed by top ring reversal temperatures of 550 C was met through the development of vapor phase lubrication using tricresyl phosphate at the ring-liner interface. A solenoid-controlled, variable valve actuation system that eliminated the conventional camshaft was demonstrated on the test bed. High pressure fuel injection via a common rail system was also developed to reduce particulate emissions.

Advanced diesel engine component development program, tasks 4-14

NASA Technical Reports Server (NTRS)

Kaushal, Tony S.; Weber, Karen E.

1994-01-01

This report summarizes the Advanced Diesel Engine Component Development (ADECD) Program to develop and demonstrate critical technology needed to advance the heavy-duty low heat rejection engine concept. Major development activities reported are the design, analysis, and fabrication of monolithic ceramic components; vapor phase and solid film lubrication; electrohydraulic valve actuation; and high pressure common rail injection. An advanced single cylinder test bed was fabricated as a laboratory tool in studying these advanced technologies. This test bed simulates the reciprocator for a system having no cooling system, turbo compounding, Rankine bottoming cycle, common rail injection, and variable valve actuation to achieve fuel consumption of 160 g/kW-hr (.26 lb/hp-hr). The advanced concepts were successfully integrated into the test engine. All ceramic components met their functional and reliability requirements. The firedeck, cast-in-place ports, valves, valve guides, piston cap, and piston ring were made from silicon nitride. Breakthroughs required to implement a 'ceramic' engine included the fabrication of air-gap cylinder heads, elimination of compression gaskets, machining of ceramic valve seats within the ceramic firedeck, fabrication of cast-in-place ceramic port liners, implementation of vapor phase lubrication, and elimination of the engine coolant system. Silicon nitride valves were successfully developed to meet several production abuse test requirements and incorporated into the test bed with a ceramic valve guide and solid film lubrication. The ADECD cylinder head features ceramic port shields to increase insulation and exhaust energy recovery. The combustion chamber includes a ceramic firedeck and piston cap. The tribological challenge posed by top ring reversal temperatures of 550 C was met through the development of vapor phase lubrication using tricresyl phosphate at the ring-liner interface. A solenoid-controlled, variable valve actuation system that eliminated the conventional camshaft was demonstrated on the test bed. High pressure fuel injection via a common rail system was also developed to reduce particulate emissions.

[Preparation of porous ceramics based on waste ceramics and its Ni2+ adsorption characteristics].

PubMed

Zhang, Yong-Li; Wang, Cheng-Zhi; Shi, Ce; Shang, Ling-Ling; Ma, Rui; Dong, Wan-Li

2013-07-01

The preparation conditions of porous ceramics were determined by SEM, XRD and FT-IR characterizations as well as the nickel removal ability of porous ceramics to be: the mass fraction w of sesbania powder doped was 4%, and the calcination temperature was 800 degrees C. SEM and pore structure characterization illustrated that calcination caused changes in the structure and morphology of waste ceramics. With the increase of calcination temperature, the specific surface area and pore volume decreased, while the aperture increased. EDS analyses showed that the main elements of both the original waste porcelain powder and the porous ceramics were Si, Al and O. The SEM, XRD and FT-IR characterization of porous ceramics illustrated that the structure of porous ceramics was stable before and after adsorption. The series of experiments of Ni2+ adsorption using these porous ceramics showed that when the dosage of porous ceramics was 10 g x L(-1), the adsorption time was 60 min, the pH value was 6.32, and the concentration of nickel-containing wastewater was below 100 mg x L(-1), the Ni2+ removal of wastewater reached 89.7%. Besides, the porous ceramics showed higher removal efficiency on nickel in the wastewater. The Ni(2+)-containing wastewater was processed by the porous ceramics prepared, and the adsorption dynamics and adsorption isotherms of Ni2+ in wastewater by porous ceramics were investigated. The research results showed that the Ni2+ adsorption process of porous ceramics was in accordance with the quasi second-order kinetic model (R2 = 0.999 9), with Q(e) of 9.09 mg x g(-1). The adsorption process can be described by the Freundlich equation and Langmuir equation, and when the temperature increased from 20 degrees C to 40 degrees C, the maximum adsorption capacity Q(m) increased from 14.49 mg x g(-1) to 15.38 mg x g(-1).

Prepreg and Melt Infiltration Technology Developed for Affordable, Robust Manufacturing of Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Petko, Jeannie F.

2004-01-01

Affordable fiber-reinforced ceramic matrix composites with multifunctional properties are critically needed for high-temperature aerospace and space transportation applications. These materials have various applications in advanced high-efficiency and high-performance engines, airframe and propulsion components for next-generation launch vehicles, and components for land-based systems. A number of these applications require materials with specific functional characteristics: for example, thick component, hybrid layups for environmental durability and stress management, and self-healing and smart composite matrices. At present, with limited success and very high cost, traditional composite fabrication technologies have been utilized to manufacture some large, complex-shape components of these materials. However, many challenges still remain in developing affordable, robust, and flexible manufacturing technologies for large, complex-shape components with multifunctional properties. The prepreg and melt infiltration (PREMI) technology provides an affordable and robust manufacturing route for low-cost, large-scale production of multifunctional ceramic composite components.

A new active solder for joining electronic components

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

SMITH,RONALD W.; VIANCO,PAUL T.; HERNANDEZ,CYNTHIA L.

Electronic components and micro-sensors utilize ceramic substrates, copper and aluminum interconnect and silicon. The joining of these combinations require pre-metallization such that solders with fluxes can wet such combinations of metals and ceramics. The paper will present a new solder alloy that can bond metals, ceramics and composites. The alloy directly wets and bonds in air without the use flux or premetallized layers. The paper will present typical processing steps and joint microstructures in copper, aluminum, aluminum oxide, aluminum nitride, and silicon joints.

Mounting apparatus for a nozzle guide vane assembly

DOEpatents

Boyd, G.L.; Shaffer, J.E.

1995-09-12

The present invention provides a ceramic nozzle guide assembly with an apparatus for mounting it to a metal nozzle case that includes an intermediate ceramic mounting ring. The mounting ring includes a plurality of projections that are received within a plurality of receptacles formed in the nozzle case. The projections of the mounting ring are secured within the receptacles by a ceramic retainer that allows contact between the two components only along arcuate surfaces thus eliminating sliding contact between the components. 8 figs.

Mounting apparatus for a nozzle guide vane assembly

DOEpatents

Boyd, Gary L.; Shaffer, James E.

1995-01-01

The present invention provides a ceramic nozzle guide assembly with an apparatus for mounting it to a metal nozzle case that includes an intermediate ceramic mounting ring. The mounting ring includes a plurality of projections that are received within a plurality of receptacles formed in the nozzle case. The projections of the mounting ring are secured within the receptacles by a ceramic retainer that allows contact between the two components only along arcuate surfaces thus eliminating sliding contact between the components.

Dielectric relaxation related to single-ionized oxygen vacancies in (Pb{sub 1-x}La{sub x})(Zr{sub 0.90}Ti{sub 0.10}){sub 1-x/4}O{sub 3} ceramics

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

Pelaiz-Barranco, A., E-mail: pelaiz@fisica.uh.cu; Guerra, J.D.S.

2010-09-15

The dielectric relaxation phenomenon has been studied in lanthanum modified lead zirconate titanate ceramics in the high temperature paraelectric phase. The high temperature dielectric response revealed an anomalous behavior, which is characterized by an increase of the real component of the dielectric permittivity with the increase of the temperature. At the same time, a similar behavior, with very high values, has been observed in the imaginary component of the dielectric permittivity, which can be associated with conduction effects related to the conductivity losses. The frequency and temperature behavior of the complex dielectric permittivity has been analyzed considering the semi-empirical complexmore » Cole-Cole equation. The activation energy value, obtained from the Arrhenius' dependence for the relaxation time, was found to decreases with the increase of the lanthanum concentration and has been associated with single-ionized oxygen vacancies. The short-range hopping of oxygen vacancies is discussed as the main cause of the dielectric relaxation.« less

Joining and Integration of Silicon Carbide-Based Materials for High Temperature Applications

NASA Technical Reports Server (NTRS)

Halbig, Michael C.; Singh, Mrityunjay

2016-01-01

Advanced joining and integration technologies of silicon carbide-based ceramics and ceramic matrix composites are enabling for their implementation into wide scale aerospace and ground-based applications. The robust joining and integration technologies allow for large and complex shapes to be fabricated and integrated with the larger system. Potential aerospace applications include lean-direct fuel injectors, thermal actuators, turbine vanes, blades, shrouds, combustor liners and other hot section components. Ground based applications include components for energy and environmental systems. Performance requirements and processing challenges are identified for the successful implementation different joining technologies. An overview will be provided of several joining approaches which have been developed for high temperature applications. In addition, various characterization approaches were pursued to provide an understanding of the processing-microstructure-property relationships. Microstructural analysis of the joint interfaces was conducted using optical, scanning electron, and transmission electron microscopy to identify phases and evaluate the bond quality. Mechanical testing results will be presented along with the need for new standardized test methods. The critical need for tailoring interlayer compositions for optimum joint properties will also be highlighted.

Neutral ion sources in precision manufacturing

NASA Technical Reports Server (NTRS)

Fawcett, Steven C.; Drueding, Thomas W.

1994-01-01

Ion figuring of optical components is a relatively new technology that can alleviate some of the problems associated with traditional contact polishing. Because the technique is non contacting, edge distortions and rib structure print through do not occur. This initial investigation was aimed at determining the effect of ion figuring on surface roughness of previously polished or ductile ground ceramic optical samples. This is the first step in research directed toward the combination of a pre-finishing process (ductile grinding or polishing) with ion figuring to produce finished ceramic mirrors. The second phase of the project is focusing on the development of mathematical algorithms that will deconvolve the ion beam profile from the surface figure errors so that these errors can be successfully removed from the optical components. In the initial phase of the project, multiple, chemical vapor deposited silicon carbide (CVD SiC) samples were polished or ductile ground to specular or near-specular roughness. These samples were then characterized to determine topographic surface information. The surface evaluation consisted of stylus profilometry, interferometry, and optical and scanning electron microscopy. The surfaces, were ion machined to depths from 0-5 microns. The finished surfaces were characterized to evaluate the effects of the ion machining process with respect to the previous processing methods and the pre-existing subsurface damage. The development of the control algorithms for figuring optical components has been completed. These algorithms have been validated with simulations and future experiments have been planned to verify the methods. This paper will present the results of the initial surface finish experiments and the control algorithms simulations.

Enabling Technologies for Ceramic Hot Section Components

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

Venkat Vedula; Tania Bhatia

Silicon-based ceramics are attractive materials for use in gas turbine engine hot sections due to their high temperature mechanical and physical properties as well as lower density than metals. The advantages of utilizing ceramic hot section components include weight reduction, and improved efficiency as well as enhanced power output and lower emissions as a result of reducing or eliminating cooling. Potential gas turbine ceramic components for industrial, commercial and/or military high temperature turbine applications include combustor liners, vanes, rotors, and shrouds. These components require materials that can withstand high temperatures and pressures for long duration under steam-rich environments. For Navymore » applications, ceramic hot section components have the potential to increase the operation range. The amount of weight reduced by utilizing a lighter gas turbine can be used to increase fuel storage capacity while a more efficient gas turbine consumes less fuel. Both improvements enable a longer operation range for Navy ships and aircraft. Ceramic hot section components will also be beneficial to the Navy's Growth Joint Strike Fighter (JSF) and VAATE (Versatile Affordable Advanced Turbine Engines) initiatives in terms of reduced weight, cooling air savings, and capability/cost index (CCI). For DOE applications, ceramic hot section components provide an avenue to achieve low emissions while improving efficiency. Combustors made of ceramic material can withstand higher wall temperatures and require less cooling air. Ability of the ceramics to withstand high temperatures enables novel combustor designs that have reduced NO{sub x}, smoke and CO levels. In the turbine section, ceramic vanes and blades do not require sophisticated cooling schemes currently used for metal components. The saved cooling air could be used to further improve efficiency and power output. The objectives of this contract were to develop technologies critical for ceramic hot section components for gas turbine engines. Significant technical progress has been made towards maturation of the EBC and CMC technologies for incorporation into gas turbine engine hot-section. Promising EBC candidates for longer life and/or higher temperature applications relative to current state of the art BSAS-based EBCs have been identified. These next generation coating systems have been scaled-up from coupons to components and are currently being field tested in Solar Centaur 50S engine. CMC combustor liners were designed, fabricated and tested in a FT8 sector rig to demonstrate the benefits of a high temperature material system. Pretest predictions made through the use of perfectly stirred reactor models showed a 2-3x benefit in CO emissions for CMC versus metallic liners. The sector-rig test validated the pretest predictions with >2x benefit in CO at the same NOx levels at various load conditions. The CMC liners also survived several trip shut downs thereby validating the CMC design methodology. Significant technical progress has been made towards incorporation of ceramic matrix composites (CMC) and environmental barrier coatings (EBC) technologies into gas turbine engine hot-section. The second phase of the program focused on the demonstration of a reverse flow annular CMC combustor. This has included overcoming the challenges of design and fabrication of CMCs into 'complex' shapes; developing processing to apply EBCs to 'engine hardware'; testing of an advanced combustor enabled by CMCs in a PW206 rig; and the validation of performance benefits against a metal baseline. The rig test validated many of the pretest predictions with a 40-50% reduction in pattern factor compared to the baseline and reductions in NOx levels at maximum power conditions. The next steps are to develop an understanding of the life limiting mechanisms in EBC and CMC materials, developing a design system for EBC coated CMCs and durability testing in an engine environment.« less

Ceramic Stereolithography: Additive Manufacturing for Ceramics by Photopolymerization

NASA Astrophysics Data System (ADS)

Halloran, John W.

2016-07-01

Ceramic stereolithography and related additive manufacturing methods involving photopolymerization of ceramic powder suspensions are reviewed in terms of the capabilities of current devices. The practical fundamentals of the cure depth, cure width, and cure profile are related to the optical properties of the monomer, ceramic, and photo-active components. Postpolymerization steps, including harvesting and cleaning the objects, binder burnout, and sintering, are discussed and compared with conventional methods. The prospects for practical manufacturing are discussed.

Transparent ceramic garnet scintillator optimization via composition and co-doping for high-energy resolution gamma spectrometers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Beck, Patrick R.; Swanberg, Erik L.; Hunter, Steven L.

2016-09-01

Breakthrough energy resolution, R(662keV) <4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce), by optimizing fabrication conditions. Here we describe the dependence of scintillation light yield and energy resolution on several variables: (1) Stoichiometry, in particular Gd/Y and Ga/Al ratios which modify the bandgap energy, (2) Processing methods, including vacuum vs. oxygen sintering, and (3) Trace co-dopants that influence the formation of Ce4+ and modify the intra-bandgap trap distribution. To learn about how chemical composition influences the scintillation properties of transparent ceramic garnet scintillators, we have measured: scintillation decay component amplitudes; intensity and duration of afterglow; thermoluminescence glow curve peak positions and amplitudes; integrated light yield; light yield non-proportionality, as measured in the Scintillator Light Yield Non-Proportionality Characterization Instrument (SLYNCI); and energy resolution for gamma spectroscopy. Optimized GYGAG(Ce) provides R(662 keV) =3.0%, for 0.05 cm3 size ceramics with Silicon photodiode readout, and R(662 keV) =4.6%, at 2 in3 size with PMT readout.

Engineering long term clinical success of advanced ceramic prostheses.

PubMed

Rekow, Dianne; Thompson, Van P

2007-01-01

Biocompatability and, in some applications, esthetics make all-ceramic prostheses compelling choices but despite significant improvements in materials properties and toughening mechanisms, these still have significant failure rates. Factors that contribute to the degradation in strength and survival include material selection and prosthesis design which set the upper limit for performance. However, fabrication operations introduce damage that can be exacerbated by environmental conditions and clinical function. Using all-ceramic dental crowns as an example, experimentally derived models provide insight into the relationships between materials properties and initial critical loads to failure. Analysis of fabrication operations suggests strategies to minimize damage. Environmental conditions can create viscoplastic flow of supporting components which can contribute additional stress within the prosthesis. Fatigue is a particularly challenging problem, not only providing the energy to propagate existing damage but, when combined with the wet environment, can create new damage modes. While much is known, the influence of these new damage modes has not been completely elucidated. The role of complex prosthesis geometry and its interaction with other factors on damage initiation and propagation has yet to be well characterized.

Development and Testing of Ceramic Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Choi, Sung R.; Miller, Robert A.

2004-01-01

Ceramic thermal barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. Durability of the coating systems remains a critical issue with the ever-increasing temperature requirements. Thermal conductivity increase and coating degradation due to sintering and phase changes are known to be detrimental to coating performance. There is a need to characterize the coating behavior and temperature limits, in order to potentially take full advantage of the current coating capability, and also accurately assess the benefit gained from advanced coating development. In this study, thermal conductivity behavior and cyclic durability of plasma-sprayed ZrO2-8wt%Y2O3 thermal barrier coatings were evaluated under laser heat-flux simulated high temperature, large thermal gradient and thermal cycling conditions. The coating degradation and failure processes were assessed by real-time monitoring of the coating thermal conductivity under the test conditions. The ceramic coating crack propagation driving forces and resulting failure modes will be discussed in light of high temperature mechanical fatigue and fracture testing results.

Advances in Thin Film Sensor Technologies for Engine Applications

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Martin, Lisa C.; Will, Herbert A.

1997-01-01

Advanced thin film sensor techniques that can provide accurate surface strain and temperature measurements are being developed at NASA Lewis Research Center. These sensors are needed to provide minimally intrusive characterization of advanced materials (such as ceramics and composites) and structures (such as components for Space Shuttle Main Engine, High Speed Civil Transport, Advanced Subsonic Transports and General Aviation Aircraft) in hostile, high-temperature environments and for validation of design codes. This paper presents two advanced thin film sensor technologies: strain gauges and thermocouples. These sensors are sputter deposited directly onto the test articles and are only a few micrometers thick; the surface of the test article is not structurally altered and there is minimal disturbance of the gas flow over the surface. The strain gauges are palladium-13% chromium based and the thermocouples are platinum-13% rhodium vs. platinum. The fabrication techniques of these thin film sensors in a class 1000 cleanroom at the NASA Lewis Research Center are described. Their demonstration on a variety of engine materials, including superalloys, ceramics and advanced ceramic matrix composites, in several hostile, high-temperature test environments are discussed.

Development and Fatigue Testing of Ceramic Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Choi, Sung R.; Miller, Robert A.

2004-01-01

Ceramic thermal barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. Durability of the coating systems remains a critical issue with the ever-increasing temperature requirements. Thermal conductivity increase and coating degradation due to sintering and phase changes are known to be detrimental to coating performance. There is a need to characterize the coating thermal fatigue behavior and temperature limit, in order to potentially take full advantage of the current coating capability. In this study, thermal conductivity and cyclic fatigue behaviors of plasma-sprayed ZrO2-8wt%Y2O3 thermal barrier coatings were evaluated under high temperature, large thermal gradient and thermal cycling conditions. The coating degradation and failure processes were assessed by real-time monitoring of the coating thermal conductivity under the test conditions. The ceramic coating crack initiation and propagation driving forces and failure modes under the cyclic thermal loads will be discussed in light of the high temperature mechanical fatigue and fracture testing results.

Resistance to abrasion of extrinsic porcelain esthetic characterization techniques.

PubMed

Chi, Woo J; Browning, William; Looney, Stephen; Mackert, J Rodway; Windhorn, Richard J; Rueggeberg, Frederick

2017-01-01

A novel esthetic porcelain characterization technique involves mixing an appropriate amount of ceramic colorants with clear, low-fusing porcelain (LFP), applying the mixture on the external surfaces, and firing the combined components onto the surface of restorations in a porcelain oven. This method may provide better esthetic qualities and toothbrush abrasion resistance compared to the conventional techniques of applying color-corrective porcelain colorants alone, or applying a clear glaze layer over the colorants. However, there is no scientific literature to support this claim. This research evaluated toothbrush abrasion resistance of a novel porcelain esthetic characterization technique by subjecting specimens to various durations of simulated toothbrush abrasion. The results were compared to those obtained using the conventional characterization techniques of colorant application only or colorant followed by placement of a clear over-glaze. Four experimental groups, all of which were a leucite reinforced ceramic of E TC1 (Vita A1) shade, were prepared and fired in a porcelain oven according to the manufacturer's instructions. Group S (stain only) was characterized by application of surface colorants to provide a definitive shade of Vita A3.5. Group GS (glaze over stain) was characterized by application of a layer of glaze over the existing colorant layer as used for Group S. Group SL (stain+LFP) was characterized by application of a mixture of colorants and clear low-fusing add-on porcelain to provide a definitive shade of Vita A3.5. Group C (Control) was used as a control without any surface characterization. The 4 groups were subjected to mechanical toothbrushing using a 1:1 water-to-toothpaste solution for a simulated duration of 32 years of clinical use. The amount of wear was measured at time intervals simulating every 4 years of toothbrushing. These parameters were evaluated longitudinally for all groups as well as compared at similar time points among groups. In this study, the novel external characterization technique (stain+LFP: Group SL) did not significantly enhance the wear resistance against toothbrush abrasion. Instead, the average wear of the applied extrinsic porcelain was 2 to 3 times more than Group S (stain only) and Group GS (glaze over stain). Application of a glaze layer over the colorants (Group GS) showed a significant improvement on wear resistance. Despite its superior physical properties, the leucite reinforced ceramic core (Group C) showed 2 to 4 times more wear when compared with other test groups. A conventional external esthetic characterization technique of applying a glaze layer over the colorants (Group GS) significantly enhanced the surface wear resistance to toothbrush abrasion when compared with other techniques involving application of colorants only (Group S) or mixture of colorant and LFP (Group SL). The underlying core ceramic had significantly less wear resistance compared with all externally characterized specimens. The novel esthetic characterization technique showed more wear and less color stability, and is thus not advocated as the "best" method for surface characterization. Application of a glaze layer provides a more wear-resistant surface from toothbrush abrasion when adjusting or extrinsically characterizing leucite reinforced ceramic restorations. Without the glaze layer, the restoration is subjected to a 2 to 4 times faster rate and amount of wear leading to possible shade mismatch.

Polymer, metal and ceramic matrix composites for advanced aircraft engine applications

NASA Technical Reports Server (NTRS)

Mcdanels, D. L.; Serafini, T. T.; Dicarlo, J. A.

1985-01-01

Advanced aircraft engine research within NASA Lewis is being focused on propulsion systems for subsonic, supersonic, and hypersonic aircraft. Each of these flight regimes requires different types of engines, but all require advanced materials to meet their goals of performance, thrust-to-weight ratio, and fuel efficiency. The high strength/weight and stiffness/weight properties of resin, metal, and ceramic matrix composites will play an increasingly key role in meeting these performance requirements. At NASA Lewis, research is ongoing to apply graphite/polyimide composites to engine components and to develop polymer matrices with higher operating temperature capabilities. Metal matrix composites, using magnesium, aluminum, titanium, and superalloy matrices, are being developed for application to static and rotating engine components, as well as for space applications, over a broad temperature range. Ceramic matrix composites are also being examined to increase the toughness and reliability of ceramics for application to high-temperature engine structures and components.

Nondestructive evaluation of ceramic and metal matrix composites for NASA's HITEMP and enabling propulsion materials programs

NASA Technical Reports Server (NTRS)

Generazio, Edward R.

1992-01-01

In a preliminary study, ultrasonic, x-ray opaque, and fluorescent dye penetrants techniques were used to evaluate and characterize ceramic and metal matrix composites. Techniques are highlighted for identifying porosity, fiber alignment, fiber uniformity, matrix cracks, fiber fractures, unbonds or disbonds between laminae, and fiber-to-matrix bond variations. The nondestructive evaluations (NDE) were performed during processing and after thermomechanical testing. Specific examples are given for Si3N4/SiC (SCS-6 fiber), FeCrAlY/Al2O3 fibers, Ti-15-3/SiC (SCS-6 fiber) materials, and Si3N4/SiC (SCS-6 fiber) actively cooled panel components. Results of this study indicate that the choice of the NDE tools to be used can be optimized to yield a faithful and accurate evaluation of advanced composites.

The thermal stability of sodium beta'-Alumina solid electrolyte ceramic in AMTEC cells

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

Williams, Roger M.; Ryan, Margaret A.; Homer, Margie L.

1999-01-22

A critical component of alkali metal thermal-to electric converter (AMTEC) devices for long duration space missions is the beta'-alumina solid electrolyte ceramic (BASE), for which there exists no substitute. The temperature and environmental conditions under which BASE remains stable control operational parameters of AMTEC devices. We have used mass loss experiments in vacuum to 1573K to characterize the kinetics of BASE decomposition, and conductivity and exchange current measurements in sodium vapor filled exposure cells to 1223K to investigate changes in the BASE which affect its ionic conductivity. There is no clear evidence of direct thermal decomposition of BASE below 1273K,more » although limited soda loss may occur. Reactive metals such as Mn or Cr can react with BASE at temperatures at least as low as 1223K.« less

NDE for Material Characterization in Aeronautic and Space Applications

NASA Technical Reports Server (NTRS)

Baaklini, George Y.; Kautz, Harold E.; Gyekenyesi, Andrew L.; Abdul-Aziz, Ali; Martin, Richard E.

2000-01-01

This paper describes selected nondestructive evaluation (NDE) approaches that were developed or tailored at the NASA Glenn Research Center for characterizing advanced material systems. The emphasis is on high-temperature aerospace propulsion applications. The material systems include monolithic ceramics, superalloys, and high temperature composites. In the aeronautic area, the highlights are cooled ceramic plate structures for turbine applications, F-TiAl blade materials for low-pressure turbines, thermoelastic stress analysis (TSA) for residual stress measurements in titanium based and nickel based engine materials, and acousto ultrasonics (AU) for creep damage assessment in nickel-based alloys. In the space area, examples consist of cooled carbon-carbon composites for gas generator combustors and flywheel rotors composed of carbon fiber reinforced polymer matrix composites for energy storage on the international space station (ISS). The role of NDE in solving manufacturing problems, the effect of defects on structural behavior, and the use of NDE-based finite element modeling are discussed. NDE technology needs for improved microelectronic and mechanical systems as well as health monitoring of micro-materials and components are briefly discussed.

Uses of ceramics in microelectronics: A survey

NASA Technical Reports Server (NTRS)

Bratschun, W. R.; Mountvala, A. J.; Pincus, A. G.

1971-01-01

The properties and behavior of ceramic materials used in components for electronic circuitry are examined to appraise the present and future directions for microelectronics, and to suggest further product development, and how innovations may be useful in other technologies. Ceramic and glass insulators, resistors, capacitors, and the use of ceramics and glasses in microcircuitry are discussed along with technology transfer to nonaerospace uses.

Standardization Efforts for Mechanical Testing and Design of Advanced Ceramic Materials and Components

NASA Technical Reports Server (NTRS)

Salem, Jonathan A.; Jenkins, Michael G.

2003-01-01

Advanced aerospace systems occasionally require the use of very brittle materials such as sapphire and ultra-high temperature ceramics. Although great progress has been made in the development of methods and standards for machining, testing and design of component from these materials, additional development and dissemination of standard practices is needed. ASTM Committee C28 on Advanced Ceramics and ISO TC 206 have taken a lead role in the standardization of testing for ceramics, and recent efforts and needs in standards development by Committee C28 on Advanced Ceramics will be summarized. In some cases, the engineers, etc. involved are unaware of the latest developments, and traditional approaches applicable to other material systems are applied. Two examples of flight hardware failures that might have been prevented via education and standardization will be presented.

Chemical cleaning-associated generation of dissolved organic matter and halogenated byproducts in ceramic MBR: Ozone versus hypochlorite.

PubMed

Sun, Huifang; Liu, Hang; Han, Jiarui; Zhang, Xiangru; Cheng, Fangqin; Liu, Yu

2018-09-01

This study characterized the dissolved organic matter (DOM) and byproducts generated after the exposure of activated sludge to ozone and NaClO in ceramic MBR. It was found that NaClO triggered more significant release of DOM than ozone. Proteins with the molecular weight greater than 20 kDa and humic acid like-substances were the principal components of DOM generated by NaClO, while ozone was found to effectively degrade larger biopolymers to low molecular weight substances. The results showed that more than 80% of DOM generated by NaClO and ozone could pass through the 0.2-μm ceramic membrane. Furthermore, total organic chlorine (TOCl) was determined to be the principal species of halogenated byproducts in both cases, while the generation of TOCl by NaClO was much more significant than that by ozone. Only a small fraction of TOCl was removed by the 0.2-μm ceramic membrane. More importantly, the toxic bioassays further revealed that the supernatant of sludge suspension and permeate in the MBR with NaClO cleaning exhibited higher developmental toxicity to the polychaete embryos than those by ozone. The results clearly showed that on-line chemical cleaning with ozone should be a more eco-friendly and safer approach for sustaining long-term membrane permeability in ceramic MBR. Copyright © 2018 Elsevier Ltd. All rights reserved.

Carbon nanotube-ceramic nanocomposites: Synthesis and characterization

NASA Astrophysics Data System (ADS)

Clark, Michael David

Ceramic materials are widely used in modern society for a variety of applications including fuel cell electrolytes, bio-medical implants, and jet turbines. However, ceramics are inherently brittle making them excellent candidates for mechanical reinforcement. In this work, the feasibility of dispersing multi-walled carbon nanotubes into a silicon carbide matrix for mechanical property enhancement is explored. Prior to dispersing, nanotubes were purified using an optimized, three step methodology that incorporates oxidative treatment, acid sonication, and thermal annealing rendering near-superhydrophobic behavior in synthesized thin films. Alkyl functionalized nanotube dispersability was characterized in various solvents. Dispersability was contingent on fostering polar interactions between the functionalized nanotubes and solvent despite the purely dispersive nature of the aliphatic chains. Interpretation of these results yielded values of 45.6 +/- 1.2, 0.78 +/- 0.04, and 2 4 +/- 0.9 mJ/m2 for the Lifshitz-van der Waals, electron acceptor and electron donor surface energy components respectively. Aqueous nanotube dispersions were prepared using a number of surfactants to examine surfactant concentration and pH effects on nanotube dispersability. Increasing surfactant concentrations resulted in a solubility plateau, which was independent of the surfactant's critical micelle concentration. Deviations from neutral pH demonstrated negligible influence on non-ionic surfactant adsorption while, ionic surfactants showed substantial pH dependent behavior. These results were explained in the context of nanotube surface ionization and Debye length variation. Successful MWNT dispersion into a silicon carbide based matrix is reported by in-situ ceramic formation using two routes; sol-gel chemistry and pre-ceramic polymeric precursor workup. For the former, nanotube dispersion was assisted by PluronicRTM surfactants. Pyrolytic treatment and consolidation of formed powders yielded ceramic silicon oxycarbide glasses (SiO1.1 C0.6) attributed to incomplete carbothermal reduction. Microhardness and dynamic moduli measurements were consistent with silicon oxycarbide glasses and unaffected by nanotube loading up to 0.11 wt. %. Pyrolysis and densification of poly(methylsilyne) yielded a high density ceramic material (2.45-2.63 g/cm 3). Nanotube introduction was achieved using two separate alkylation techniques; alkyllithium replacement and organic peroxide workup. Bulk mechanical testing was deemed unreliable as powder consolidation introduced chemical inhomogeneity with pellet edges being largely composed of polycrystalline silicon and silicon carbide, while the center contained substantial oxygen contamination.

Continuum Damage Mechanics Used to Predict the Creep Life of Monolithic Ceramics

NASA Technical Reports Server (NTRS)

Powers, Lynn M.; Jadaan, Osama M.

1998-01-01

Significant improvements in propulsion and power generation for the next century will require revolutionary advances in high-temperature materials and structural design. Advanced ceramics are candidate materials for these elevated temperature applications. High-temperature and long-duration applications of monolithic ceramics can place their failure mode in the creep rupture regime. An analytical methodology in the form of the integrated design program-Ceramics Analysis and Reliability Evaluation of Structures/Creep (CARES/Creep) has been developed by the NASA Lewis Research Center to predict the life of ceramic structural components subjected to creep rupture conditions. This program utilizes commercially available finite element packages and takes into account the transient state of stress and creep strain distributions (stress relaxation as well as the asymmetric response to tension and compression). The creep life of a component is discretized into short time steps, during which the stress distribution is assumed constant. Then, the damage is calculated for each time step on the basis of a modified Monkman-Grant (MMG) creep rupture criterion. The cumulative damage is subsequently calculated as time elapses in a manner similar to Miner's rule for cyclic fatigue loading. Failure is assumed to occur when the normalized cumulative damage at any point in the component reaches unity. The corresponding time is the creep rupture life for that component.

Scintillation and optical properties of TiO2-ZnO-Al2O3-B2O3 glasses and glass-ceramics

NASA Astrophysics Data System (ADS)

Usui, Yuki; Okada, Go; Kawaguchi, Noriaki; Masai, Hirokazu; Yanagida, Takayuki

2018-04-01

13TiO2-xZnO-17Al2O3-(70 - x)B2O3 (x = 17, 26, and 35) glasses were prepared by a melt-quenching method, and the obtained glass samples were heated at temperatures 30 °C above the glass transition temperature of corresponding glass in order to obtain glass-ceramics. The obtained glass-ceramic samples were confirmed to have anatase (x = 17) and rutile (x = 26 and 35) phases from X-ray diffraction analysis. Then, the scintillation and optical properties were evaluated and discussed the difference between the glass-ceramic and glass samples. In the scintillation spectra under X-ray irradiation, a broad emission peak was observed around 450 nm in all the samples, and the new peak around 500 nm appeared in the anatase-precipitated glass-ceramic. The intensities of the glass-ceramic samples were enhanced in comparison with the corresponding glasses because the glass-ceramics includes TiO2 crystallites with defect centers which act as effective emission centers. The scintillation decay curves of the glass and glass-ceramic samples were approximated by one and a sum of two exponential decay functions, respectively. The faster component of glass and glass-ceramic samples would be caused by the host emission, and the slower component of glass-ceramic sample would be ascribed to the emission of Ti3+.

On the design and development of a miniature ceramic gimbal bearing

NASA Technical Reports Server (NTRS)

Hanson, Robert A.; Odwyer, Barry; Gordon, Keith M.; Jarvis, Edward W.

1990-01-01

A review is made of a program to develop ceramic gimbal bearings for a miniaturized missile guidance system requiring nonmagnetic properties and higher load capacity than possible with conventional AISI 440C stainless steel bearings. A new gimbal design concept is described which utilizes the compressive strength and nonmagnetic properties of silicon nitride (Si3N4) ceramics for the gimbal bearing. Considerable manufacturing development has occurred in the last 5 years making ceramic bearings a viable option in the gimbal design phase. A preliminary study into the feasibility of the proposed design is summarized. Finite element analysis of the brittle ceramic bearing components under thermal stress and high acceleration loading were conducted to ensure the components will not fail catastrophically in service. Finite element analysis was also used to optimize the adhesive joint design. Bearing torque tests run at various axial loads indicate that the average running torque of ceramic bearings varies with load similarly to that of conventional steel bearings.

Characterization of composite materials based on cement-ceramic powder blended binder

NASA Astrophysics Data System (ADS)

Kulovaná, Tereza; Pavlík, Zbyšek

2016-06-01

Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO2 emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzed by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.

Characterization of composite materials based on cement-ceramic powder blended binder

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

Kulovaná, Tereza; Pavlík, Zbyšek

Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO{sub 2} emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzedmore » by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.« less

Glass ceramic ZERODUR enabling nanometer precision

NASA Astrophysics Data System (ADS)

Jedamzik, Ralf; Kunisch, Clemens; Nieder, Johannes; Westerhoff, Thomas

2014-03-01

The IC Lithography roadmap foresees manufacturing of devices with critical dimension of < 20 nm. Overlay specification of single digit nanometer asking for nanometer positioning accuracy requiring sub nanometer position measurement accuracy. The glass ceramic ZERODUR® is a well-established material in critical components of microlithography wafer stepper and offered with an extremely low coefficient of thermal expansion (CTE), the tightest tolerance available on market. SCHOTT is continuously improving manufacturing processes and it's method to measure and characterize the CTE behavior of ZERODUR® to full fill the ever tighter CTE specification for wafer stepper components. In this paper we present the ZERODUR® Lithography Roadmap on the CTE metrology and tolerance. Additionally, simulation calculations based on a physical model are presented predicting the long term CTE behavior of ZERODUR® components to optimize dimensional stability of precision positioning devices. CTE data of several low thermal expansion materials are compared regarding their temperature dependence between - 50°C and + 100°C. ZERODUR® TAILORED 22°C is full filling the tight CTE tolerance of +/- 10 ppb / K within the broadest temperature interval compared to all other materials of this investigation. The data presented in this paper explicitly demonstrates the capability of ZERODUR® to enable the nanometer precision required for future generation of lithography equipment and processes.

CARES/Life Software for Designing More Reliable Ceramic Parts

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Powers, Lynn M.; Baker, Eric H.

1997-01-01

Products made from advanced ceramics show great promise for revolutionizing aerospace and terrestrial propulsion, and power generation. However, ceramic components are difficult to design because brittle materials in general have widely varying strength values. The CAPES/Life software eases this task by providing a tool to optimize the design and manufacture of brittle material components using probabilistic reliability analysis techniques. Probabilistic component design involves predicting the probability of failure for a thermomechanically loaded component from specimen rupture data. Typically, these experiments are performed using many simple geometry flexural or tensile test specimens. A static, dynamic, or cyclic load is applied to each specimen until fracture. Statistical strength and SCG (fatigue) parameters are then determined from these data. Using these parameters and the results obtained from a finite element analysis, the time-dependent reliability for a complex component geometry and loading is then predicted. Appropriate design changes are made until an acceptable probability of failure has been reached.

Transient Reliability Analysis Capability Developed for CARES/Life

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.

2001-01-01

The CARES/Life software developed at the NASA Glenn Research Center provides a general-purpose design tool that predicts the probability of the failure of a ceramic component as a function of its time in service. This award-winning software has been widely used by U.S. industry to establish the reliability and life of a brittle material (e.g., ceramic, intermetallic, and graphite) structures in a wide variety of 21st century applications.Present capabilities of the NASA CARES/Life code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code can compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth failure conditions CARES/Life can handle sustained and linearly increasing time-dependent loads, whereas in cyclic fatigue applications various types of repetitive constant-amplitude loads can be accounted for. However, in real applications applied loads are rarely that simple but vary with time in more complex ways such as engine startup, shutdown, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. A methodology has now been developed to allow the CARES/Life computer code to perform reliability analysis of ceramic components undergoing transient thermal and mechanical loading. This means that CARES/Life will be able to analyze finite element models of ceramic components that simulate dynamic engine operating conditions. The methodology developed is generalized to account for material property variation (on strength distribution and fatigue) as a function of temperature. This allows CARES/Life to analyze components undergoing rapid temperature change in other words, components undergoing thermal shock. In addition, the capability has been developed to perform reliability analysis for components that undergo proof testing involving transient loads. This methodology was developed for environmentally assisted crack growth (crack growth as a function of time and loading), but it will be extended to account for cyclic fatigue (crack growth as a function of load cycles) as well.

Least Squares Best Fit Method for the Three Parameter Weibull Distribution: Analysis of Tensile and Bend Specimens with Volume or Surface Flaw Failure

NASA Technical Reports Server (NTRS)

Gross, Bernard

1996-01-01

Material characterization parameters obtained from naturally flawed specimens are necessary for reliability evaluation of non-deterministic advanced ceramic structural components. The least squares best fit method is applied to the three parameter uniaxial Weibull model to obtain the material parameters from experimental tests on volume or surface flawed specimens subjected to pure tension, pure bending, four point or three point loading. Several illustrative example problems are provided.

Embedded Resistors and Capacitors in Organic and Inorganic Substrates

NASA Technical Reports Server (NTRS)

Gerke, Robert David; Ator, Danielle

2006-01-01

Embedded resistors and capacitors were purchased from two technology; organic PWB and inorganic low temperature co-fire ceramic (LTCC). Small groups of each substrate were exposed to four environmental tests and several characterization tests to evaluate their performance and reliability. Even though all passive components maintained electrical performance throughout environmental testing, differences between the two technologies were observed. Environmental testing was taken beyond manufacturers' reported testing, but general not taken to failure. When possible, data was quantitatively compared to manufacturer's data.

Structural design methodologies for ceramic-based material systems

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.; Chulya, Abhisak; Gyekenyesi, John P.

1991-01-01

One of the primary pacing items for realizing the full potential of ceramic-based structural components is the development of new design methods and protocols. The focus here is on low temperature, fast-fracture analysis of monolithic, whisker-toughened, laminated, and woven ceramic composites. A number of design models and criteria are highlighted. Public domain computer algorithms, which aid engineers in predicting the fast-fracture reliability of structural components, are mentioned. Emphasis is not placed on evaluating the models, but instead is focused on the issues relevant to the current state of the art.

Enhanced CARES Software Enables Improved Ceramic Life Prediction

NASA Technical Reports Server (NTRS)

Janosik, Lesley A.

1997-01-01

The NASA Lewis Research Center has developed award-winning software that enables American industry to establish the reliability and life of brittle material (e.g., ceramic, intermetallic, graphite) structures in a wide variety of 21st century applications. The CARES (Ceramics Analysis and Reliability Evaluation of Structures) series of software is successfully used by numerous engineers in industrial, academic, and government organizations as an essential element of the structural design and material selection processes. The latest version of this software, CARES/Life, provides a general- purpose design tool that predicts the probability of failure of a ceramic component as a function of its time in service. CARES/Life was recently enhanced by adding new modules designed to improve functionality and user-friendliness. In addition, a beta version of the newly-developed CARES/Creep program (for determining the creep life of monolithic ceramic components) has just been released to selected organizations.

Integration Science and Technology of Advanced Ceramics for Energy and Environmental Applications

NASA Technical Reports Server (NTRS)

Singh, M.

2012-01-01

The discovery of new and innovative materials has been known to culminate in major turning points in human history. The transformative impact and functional manifestation of new materials have been demonstrated in every historical era by their integration into new products, systems, assemblies, and devices. In modern times, the integration of new materials into usable products has a special relevance for the technological development and economic competitiveness of industrial societies. Advanced ceramic technologies dramatically impact the energy and environmental landscape due to potential wide scale applications in all aspects of energy production, storage, distribution, conservation, and efficiency. Examples include gas turbine propulsion systems, fuel cells, thermoelectrics, photovoltaics, distribution and transmission systems based on superconductors, nuclear power generation, and waste disposal. Robust ceramic integration technologies enable hierarchical design and manufacturing of intricate ceramic components starting with geometrically simpler units that are subsequently joined to themselves and/or to metals to create components with progressively higher levels of complexity and functionality. However, for the development of robust and reliable integrated systems with optimum performance under different operating conditions, the detailed understanding of various thermochemical and thermomechanical factors is critical. Different approaches are required for the integration of ceramic-metal and ceramic-ceramic systems across length scales (macro to nano). In this presentation, a few examples of integration of ceramic to metals and ceramic to ceramic systems will be presented. Various challenges and opportunities in design, fabrication, and testing of integrated similar (ceramic-ceramic) and dissimilar (ceramic-metal) material systems will be discussed. Potential opportunities and need for the development of innovative design philosophies, approaches, and integrated system testing under simulated application conditions will also be presented.

Microstructural and Wear Behavior Characterization of Porous Layers Produced by Pulsed Laser Irradiation in Glass-Ceramics Substrates

PubMed Central

Sola, Daniel; Conde, Ana; García, Iñaki; Gracia-Escosa, Elena; de Damborenea, Juan J.; Peña, Jose I.

2013-01-01

In this work, wear behavior and microstructural characterization of porous layers produced in glass-ceramic substrates by pulsed laser irradiation in the nanosecond range are studied under unidirectional sliding conditions against AISI316 and corundum counterbodies. Depending on the optical configuration of the laser beam and on the working parameters, the local temperature and pressure applied over the interaction zone can generate a porous glass-ceramic layer. Material transference from the ball to the porous glass-ceramic layer was observed in the wear tests carried out against the AISI316 ball counterface whereas, in the case of the corundum ball, the wear volume loss was concentrated in the porous layer. Wear rate and friction coefficient presented higher values than expected for dense glass-ceramics. PMID:28788311

Energy efficient engine high pressure turbine ceramic shroud support technology report

NASA Technical Reports Server (NTRS)

Nelson, W. A.; Carlson, R. G.

1982-01-01

This work represents the development and fabrication of ceramic HPT (high pressure turbine) shrouds for the Energy Efficient Engine (E3). Details are presented covering the work performed on the ceramic shroud development task of the NASA/GE Energy Efficient Engine (E3) component development program. The task consists of four phases which led to the selection of a ZrO2-BY2O3 ceramic shroud material system, the development of an automated plasma spray process to produce acceptable shroud structures, the fabrication of select shroud systems for evaluation in laboratory, component, and CF6-50 engine testing, and finally, the successful fabrication of ZrO2-8Y2O3/superpeg, engine quality shrouds for the E3 engine.

Ballistic Performance of Porous-Ceramic, Thermal Protection Systems to 9 km/s

NASA Technical Reports Server (NTRS)

Miller, Joshua E.; Bohl, William E.; Foreman, Cory D.; Christiansen, Eric C.; Davis, Bruce A.

2010-01-01

Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These materials insulate the structural components and sensitive components of a spacecraft against the intense thermal environments of atmospheric reentry. These materials are also highly exposed to solid particle space environment hazards. This paper discusses recent impact testing up to 9.65 km/s on ceramic tiles similar to those used on the Orbiter. These tiles are a porous-ceramic insulator of nominally 8 lb/ft(exp 3) alumina-fiber-enhanced-thermal-barrier (AETB8) coated with a damage-resistant, toughened-unipiece-fibrous-insulation/reaction-cured-glass layer (TUFI/RCG).

Method of forming a ceramic to ceramic joint

DOEpatents

Cutler, Raymond Ashton; Hutchings, Kent Neal; Kleinlein, Brian Paul; Carolan, Michael Francis

2010-04-13

A method of joining at least two sintered bodies to form a composite structure, includes: providing a joint material between joining surfaces of first and second sintered bodies; applying pressure from 1 kP to less than 5 MPa to provide an assembly; heating the assembly to a conforming temperature sufficient to allow the joint material to conform to the joining surfaces; and further heating the assembly to a joining temperature below a minimum sintering temperature of the first and second sintered bodies. The joint material includes organic component(s) and ceramic particles. The ceramic particles constitute 40-75 vol. % of the joint material, and include at least one element of the first and/or second sintered bodies. Composite structures produced by the method are also disclosed.

Impact-Resistant Ceramic Coating

NASA Technical Reports Server (NTRS)

Wheeler, W. H.; Creedon, J. F.; Izu, Y. D.

1986-01-01

Refractory fibers more than double strength of coating. Impact strengths of ceramic coatings increase with increasing whisker content. Silicon carbide whiskers clearly produce largest increase, and improvement grows even more with high-temperature sintering. Coating also improves thermal and mechanical properties of electromagnetic components, mirrors, furnace linings, and ceramic parts of advanced internal-combustion engines.

Environmental durability of ceramics and ceramic composites

NASA Technical Reports Server (NTRS)

Fox, Dennis S.

1992-01-01

An account is given of the current understanding of the environmental durability of both monolithic ceramics and ceramic-matrix composites, with a view to the prospective development of methods for the characterization, prediction, and improvement of ceramics' environmental durability. Attention is given to the environmental degradation behaviors of SiC, Si3N4, Al2O3, and glass-ceramic matrix compositions. The focus of corrosion prevention in Si-based ceramics such as SiC and Si3N4 is on the high and low sulfur fuel combustion-product effects encountered in heat engine applications of these ceramics; sintering additives and raw material impurities are noted to play a decisive role in ceramics' high temperature environmental response.

Application of CFCC technology to hot gas filtration applications

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

Richlen, S.

1995-06-01

Discussion will feature high temperature filter development under the DOE`s Office of Industrial Technologies Continuous Fiber Ceramic Composite (CFCC) Program. Within the CFCC Program there are four industry projects and a national laboratory technology support project. Atlantic Research, Babcock & Wilcox, DuPont Lanxide Composites, and Textron are developing processing methods to produce CFCC Components with various types of matrices and composites, along with the manufacturing methods to produce industrial components, including high temperature gas filters. The Oak Ridge National Laboratory is leading a National Laboratory/University effort to increase knowledge of such generic and supportive technology areas as environmental degradation, measurementmore » of mechanical properties, long-term performance, thermal shock and thermal cycling, creep and fatigue, and non-destructive characterization. Tasks include composite design, materials characterization, test methods, and performance-related phenomena, that will support the high temperature filter activities of industry and government.« less

Thermal and Environmental Barrier Coating Development for Advanced Propulsion Engine Systems

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Fox, Dennis S.

2008-01-01

Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. Advanced TEBCs that have significantly lower thermal conductivity, better thermal stability and higher toughness than current coatings will be beneficial for future low emission and high performance propulsion engine systems. In this paper, ceramic coating design and testing considerations will be described for turbine engine high temperature and high-heat-flux applications. Thermal barrier coatings for metallic turbine airfoils and thermal/environmental barrier coatings for SiC/SiC ceramic matrix composite (CMC) components for future supersonic aircraft propulsion engines will be emphasized. Further coating capability and durability improvements for the engine hot-section component applications can be expected by utilizing advanced modeling and design tools.

Electron beam gun with kinematic coupling for high power RF vacuum devices

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

Borchard, Philipp

An electron beam gun for a high power RF vacuum device has components joined by a fixed kinematic coupling to provide both precise alignment and high voltage electrical insulation of the components. The kinematic coupling has high strength ceramic elements directly bonded to one or more non-ductile rigid metal components using a high temperature active metal brazing alloy. The ceramic elements have a convex surface that mates with concave grooves in another one of the components. The kinematic coupling, for example, may join a cathode assembly and/or a beam shaping focus electrode to a gun stem, which is preferably composedmore » of ceramic. The electron beam gun may be part of a high power RF vacuum device such as, for example, a gyrotron, klystron, or magnetron.« less

Interfacial characterization of ceramic core materials with veneering porcelain for all-ceramic bi-layered restorative systems.

PubMed

Tagmatarchis, Alexander; Tripodakis, Aris-Petros; Filippatos, Gerasimos; Zinelis, Spiros; Eliades, George

2014-01-01

The aim of the study was to characterize the elemental distribution at the interface between all-ceramic core and veneering porcelain materials. Three groups of all-ceramic cores were selected: A) Glass-ceramics (Cergo, IPS Empress, IPS Empress 2, e-max Press, Finesse); B) Glass-infiltrated ceramics (Celay Alumina, Celay Zirconia) and C) Densely sintered ceramics (Cercon, Procera Alumina, ZirCAD, Noritake Zirconia). The cores were combined with compatible veneering porcelains and three flat square test specimens were produced for each system. The core-veneer interfaces were examined by scanning electron microscopy and energy dispersive x-ray microanalysis. The glass-ceramic systems showed interfacial zones reach in Si and O, with the presence of K, Ca, Al in core and Ca, Ce, Na, Mg or Al in veneer material, depending on the system tested. IPS Empress and IPS Empress 2 demonstrated distinct transitional phases at the core-veneer interface. In the glassinfiltrated systems, intermixing of core (Ce, La) with veneer (Na, Si) elements occurred, whereas an abrupt drop of the core-veneer elemental concentration was documented at the interfaces of all densely sintered ceramics. The results of the study provided no evidence of elemental interdiffusion at the core-veneer interfaces in densely sintered ceramics, which implies lack of primary chemical bonding. For the glass-containing systems (glassceramics and glass-infiltrated ceramics) interdiffusion of the glass-phase seems to play a critical role in establishing a primary bonding condition between ceramic core and veneering porcelain.

Creep Life of Ceramic Components Using a Finite-Element-Based Integrated Design Program (CARES/CREEP)

NASA Technical Reports Server (NTRS)

Powers, L. M.; Jadaan, O. M.; Gyekenyesi, J. P.

1998-01-01

The desirable properties of ceramics at high temperatures have generated interest in their use for structural application such as in advanced turbine engine systems. Design lives for such systems can exceed 10,000 hours. The long life requirement necessitates subjecting the components to relatively low stresses. The combination of high temperatures and low stresses typically places failure for monolithic ceramics in the creep regime. The objective of this paper is to present a design methodology for predicting the lifetimes of structural components subjected to creep rupture conditions. This methodology utilizes commercially available finite element packages and takes into account the time-varying creep strain distributions (stress relaxation). The creep life, of a component is discretized into short time steps, during which the stress and strain distributions are assumed constant. The damage is calculated for each time step based on a modified Monkman-Grant creep rupture criterion. Failure is assumed to occur when the normalized accumulated damage at any point in the component is greater than or equal to unity. The corresponding time will be the creep rupture life for that component. Examples are chosen to demonstrate the Ceramics Analysis and Reliability Evaluation of Structures/CREEP (CARES/CREEP) integrated design program, which is written for the ANSYS finite element package. Depending on the component size and loading conditions, it was found that in real structures one of two competing failure modes (creep or slow crack growth) will dominate. Applications to benchmark problems and engine components are included.

Creep Life of Ceramic Components Using a Finite-Element-Based Integrated Design Program (CARES/CREEP)

NASA Technical Reports Server (NTRS)

Gyekenyesi, J. P.; Powers, L. M.; Jadaan, O. M.

1998-01-01

The desirable properties of ceramics at high temperatures have generated interest in their use for structural applications such as in advanced turbine systems. Design lives for such systems can exceed 10,000 hours. The long life requirement necessitates subjecting the components to relatively low stresses. The combination of high temperatures and low stresses typically places failure for monolithic ceramics in the creep regime. The objective of this paper is to present a design methodology for predicting the lifetimes of structural components subjected to creep rupture conditions. This methodology utilized commercially available finite element packages and takes into account the time-varying creep strain distributions (stress relaxation). The creep life of a component is discretized into short time steps, during which the stress and strain distributions are assumed constant. The damage is calculated for each time step based on a modified Monkman-Grant creep rupture criterion. Failure is assumed to occur when the normalized accumulated damage at any point in the component is greater than or equal to unity. The corresponding time will be the creep rupture life for that component. Examples are chosen to demonstrate the CARES/CREEP (Ceramics Analysis and Reliability Evaluation of Structures/CREEP) integrated design programs, which is written for the ANSYS finite element package. Depending on the component size and loading conditions, it was found that in real structures one of two competing failure modes (creep or slow crack growth) will dominate. Applications to benechmark problems and engine components are included.

Effect of Ceramic Particle Velocity on Cold Spray Deposition of Metal-Ceramic Coatings

NASA Astrophysics Data System (ADS)

Sova, A.; Kosarev, V. F.; Papyrin, A.; Smurov, I.

2011-01-01

In this paper, metal-ceramic coatings are cold sprayed taking into account the spray parameters of both metal and ceramic particles. The effect of the ceramic particle velocity on the process of metal-ceramic coating formation and the coating properties is analyzed. Copper and aluminum powders are used as metal components. Two fractions of aluminum oxide and silicon carbide are sprayed in the tests. The ceramic particle velocity is varied by the particle injection into different zones of the gas flow: the subsonic and supersonic parts of the nozzle and the free jet after the nozzle exit. The experiments demonstrated the importance of the ceramic particle velocity for the stability of the process: Ceramic particles accelerated to a high enough velocity penetrate into the coating, while low-velocity ceramic particles rebound from its surface.

Correlation of compressive stress with spalling of plasma sprayed ceramic materials

NASA Technical Reports Server (NTRS)

Mullen, R. L.; Mcdonald, G.; Hendricks, R. C.; Hofle, M. M.

1983-01-01

Ceramics on metal substrates for potential use as high temperature seals or other applications are exposed to forces originating from differences in thermal expansion between the ceramic and the metal substrate. This report develops a relationship between the difference in expansion of the ceramic and the substrate, defines conditions under which shear between the ceramic and the substrate occurs, and those under which bending forces are produced in the ceramic. The off-axis effect of compression forces resulting from high temperature plastic flow of the ceramic producing buckling of the ceramic is developed. Shear is associated with the edge or boundary stresses on the component while bending is associated with the distortion of an interior region. Both modes are significant in predicting life of the ceramic.

Engineered Materials for Cesium and Strontium Storage Final Technical Report

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

Sean M. McDeavitt

2010-04-14

Closing the nuclear fuel cycle requires reprocessing spent fuel to recover the long-lived components that still have useful energy content while immobilizing the remnant waste fission products in stable forms. At the genesis of this project, next generation spent fuel reprocessing methods were being developed as part of the U.S. Department of Energy's Advanced Fuel Cycle Initiative. One of these processes was focused on solvent extraction schemes to isolate cesium (Cs) and strontium (Sr) from spent nuclear fuel. Isolating these isotopes for short-term decay storage eases the design requirements for long-term repository disposal; a significant amount of the radiation andmore » decay heat in fission product waste comes from Cs-137 and Sr-90. For the purposes of this project, the Fission Product Extraction (FPEX) process is being considered to be the baseline extraction method. The objective of this project was to evaluate the nature and behavior of candidate materials for cesium and strontium immobilization; this will include assessments with minor additions of yttrium, barium, and rubidium in these materials. More specifically, the proposed research achieved the following objectives (as stated in the original proposal): (1) Synthesize simulated storage ceramics for Cs and Sr using an existing labscale steam reformer at Purdue University. The simulated storage materials will include aluminosilicates, zirconates and other stable ceramics with the potential for high Cs and Sr loading. (2) Characterize the immobilization performance, phase structure, thermal properties and stability of the simulated storage ceramics. The ceramic products will be stable oxide powders and will be characterized to quantify their leach resistance, phase structure, and thermophysical properties. The research progressed in two stages. First, a steam reforming process was used to generate candidate Cs/Sr storage materials for characterization. This portion of the research was carried out at Purdue University and is detailed in Appendix A. Steam reforming proved to be too rigorous for efficient The second stage of this project was carried out at Texas A&M University and is Detailed in Appendix B. In this stage, a gentler ceramic synthesis process using Cs and Sr loaded kaolinite and bentonite clays was developed in collaboration with Dr. M. Kaminski at Argonne National Laboratory.« less

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1993-01-01

This report is the fifth in a series of Annual Technical Summary Reports for the Advanced Turbine Technology Applications Project (ATTAP), sponsored by the U.S. Department of Energy (DOE). The report was prepared by Garrett Auxiliary Power Division (GAPD), a unit of Allied-Signal Aerospace Company, a unit of Allied Signal, Inc. The report includes information provided by Garrett Ceramic Components, and the Norton Advanced Ceramics Company, (formerly Norton/TRW Ceramics), subcontractors to GAPD on the ATTAP. This report covers plans and progress on ceramics development for commercial automotive applications over the period 1 Jan. through 31 Dec. 1992. Project effort conducted under this contract is part of the DOE Gas Turbine Highway Vehicle System program. This program is directed to provide the U.S. automotive industry the high-risk, long-range technology necessary to produce gas turbine engines for automobiles with reduced fuel consumption, reduced environmental impact, and a decreased reliance on scarce materials and resources. The program is oriented toward developing the high-risk technology of ceramic structural component design and fabrication, such that industry can carry this technology forward to production in the 1990's. The ATTAP test bed engine, carried over from the previous AGT101 project, is being used for verification testing of the durability of next generation ceramic components, and their suitability for service at Reference Powertrain Design conditions. This document reports the technical effort conducted by GAPD and the ATTAP subcontractors during the fifth year of the project. Topics covered include ceramic processing definition and refinement, design improvements to the ATTAP test bed engine and test rigs, and the methodology development of ceramic impact and fracture mechanisms. Appendices include reports by ATTAP subcontractors in the development of silicon nitride materials and processes.

Probabilistic Prediction of Lifetimes of Ceramic Parts

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Gyekenyesi, John P.; Jadaan, Osama M.; Palfi, Tamas; Powers, Lynn; Reh, Stefan; Baker, Eric H.

2006-01-01

ANSYS/CARES/PDS is a software system that combines the ANSYS Probabilistic Design System (PDS) software with a modified version of the Ceramics Analysis and Reliability Evaluation of Structures Life (CARES/Life) Version 6.0 software. [A prior version of CARES/Life was reported in Program for Evaluation of Reliability of Ceramic Parts (LEW-16018), NASA Tech Briefs, Vol. 20, No. 3 (March 1996), page 28.] CARES/Life models effects of stochastic strength, slow crack growth, and stress distribution on the overall reliability of a ceramic component. The essence of the enhancement in CARES/Life 6.0 is the capability to predict the probability of failure using results from transient finite-element analysis. ANSYS PDS models the effects of uncertainty in material properties, dimensions, and loading on the stress distribution and deformation. ANSYS/CARES/PDS accounts for the effects of probabilistic strength, probabilistic loads, probabilistic material properties, and probabilistic tolerances on the lifetime and reliability of the component. Even failure probability becomes a stochastic quantity that can be tracked as a response variable. ANSYS/CARES/PDS enables tracking of all stochastic quantities in the design space, thereby enabling more precise probabilistic prediction of lifetimes of ceramic components.

High Temperature Joining and Characterization of Joint Properties in Silicon Carbide-Based Composite Materials

NASA Technical Reports Server (NTRS)

Halbig, Michael C.; Singh, Mrityunjay

2015-01-01

Advanced silicon carbide-based ceramics and composites are being developed for a wide variety of high temperature extreme environment applications. Robust high temperature joining and integration technologies are enabling for the fabrication and manufacturing of large and complex shaped components. The development of a new joining approach called SET (Single-step Elevated Temperature) joining will be described along with the overview of previously developed joining approaches including high temperature brazing, ARCJoinT (Affordable, Robust Ceramic Joining Technology), diffusion bonding, and REABOND (Refractory Eutectic Assisted Bonding). Unlike other approaches, SET joining does not have any lower temperature phases and will therefore have a use temperature above 1315C. Optimization of the composition for full conversion to silicon carbide will be discussed. The goal is to find a composition with no remaining carbon or free silicon. Green tape interlayers were developed for joining. Microstructural analysis and preliminary mechanical tests of the joints will be presented.

Performance of Surface-Mount Ceramic and Solid Tantalum Capacitors for Cryogenic Applications

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; MacDonald, Thomas L.; Hammoud, Ahmad; Gerber, Scott

1998-01-01

Low temperature electronics are of great interest for space exploration programs. These include missions to the outer planets, earth-orbiting and deep-space probes, remote-sensing and communication satellites. Terrestrial applications would also benefit from the availability of low temperature electronics. Power components capable of low temperature operation would, thus, enhance the technologies needed for the development of advanced power systems suitable for use in harsh environments. In this work, ceramic and solid tantalum capacitors were evaluated in terms of their dielectric properties as a function of temperature and at various frequencies. The surface-mount devices were characterized in terms of their capacitance stability and dissipation factor in the frequency range of 50 Hz to 100 kHz at temperatures ranging from room temperature (20 deg. C) to about liquid nitrogen temperature (-190 deg. C). The results are discussed and conclusions made concerning the suitability of the capacitors investigated for low temperature applications.

Study of the influence of volume fraction of ceramic inclusions in NiCr-TiC composite with columnar structure on its mechanical behavior

NASA Astrophysics Data System (ADS)

Eremina, Galina M.; Smolin, Alexey Yu.; Shilko, Evgeny V.

2017-12-01

Metal-ceramic materials are characterized by high mechanical and tribological properties. The surface treatment of the composite by an electron beam in inert gas plasma leads to a qualitative and quantitative change in its microstructure as well as to a change in mechanical properties of the components: a columnar structure forms in the modified layer. Different treatment regimes result in different concentrations of inclusions in the surface layer. In this paper, the effect of the volume concentration of inclusions on the integral mechanical properties of a dispersion-strengthened NiCr-TiC composite is studied on the basis of 3D numerical simulation. The results of computer simulation show that the change in concentration significantly affects the integral mechanical characteristics of the composite material as well as the nature of the nucleation and development of damages in it.

Functionally Graded Multifunctional Hybrid Composites for Extreme Environments

DTIC Science & Technology

2010-02-01

Develop multifunctional FGHC with multiple layers: a ceramic thermal barrier layer, a graded ceramic /metal composite (GCMeC) layer and a high...AFOSR-MURI Functionally Graded Hybrid Composites Actively Cooled PMC White (UIUC) FGHC Fabrication Team Graded Ceramic Metal Composites (GCMeC...Composites Fabrication and Characterization of Bulk Ceramic MAX Phase and MAX–Metal Composites AFOSR-MURI Functionally Graded Hybrid Composites Mn

Reduction of PM emissions from specific sources reflected on key components concentrations of ambient PM10

NASA Astrophysics Data System (ADS)

Minguillon, M. C.; Querol, X.; Monfort, E.; Alastuey, A.; Escrig, A.; Celades, I.; Miro, J. V.

2009-04-01

The relationship between specific particulate emission control and ambient levels of some PM10 components (Zn, As, Pb, Cs, Tl) was evaluated. To this end, the industrial area of Castellón (Eastern Spain) was selected, where around 40% of the EU glazed ceramic tiles and a high proportion of EU ceramic frits (middle product for the manufacture of ceramic glaze) are produced. The PM10 emissions from the ceramic processes were calculated over the period 2000 to 2007 taking into account the degree of implementation of corrective measures throughout the study period. Abatement systems (mainly bag filters) were implemented in the majority of the fusion kilns for frit manufacture in the area as a result of the application of the Directive 1996/61/CE, leading to a marked decrease in PM10 emissions. On the other hand, ambient PM10 sampling was carried out from April 2002 to July 2008 at three urban sites and one suburban site of the area and a complete chemical analysis was made for about 35 % of the collected samples, by means of different techniques (ICP-AES, ICP-MS, Ion Chromatography, selective electrode and elemental analyser). The series of chemical composition of PM10 allowed us to apply a source contribution model (Principal Component Analysis), followed by a multilinear regression analysis, so that PM10 sources were identified and their contribution to bulk ambient PM10 was quantified on a daily basis, as well as the contribution to bulk ambient concentrations of the identified key components (Zn, As, Pb, Cs, Tl). The contribution of the sources identified as the manufacture and use of ceramic glaze components, including the manufacture of ceramic frits, accounted for more than 65, 75, 58, 53, and 53% of ambient Zn, As, Pb, Cs and Tl levels, respectively (with the exception of Tl contribution at one of the sites). The important emission reductions of these sources during the study period had an impact on ambient key components levels, such that there was a high correlation between PM10 emissions from these sources and ambient key components levels (R2= 0.61-0.98).

Design and characterization of Yb and Nd doped transparent ceramics for high power laser applications: recent advancements

NASA Astrophysics Data System (ADS)

Lapucci, A.; Vannini, M.; Ciofini, M.; Pirri, A.; Nikl, M.; Li, J.; Esposito, L.; Biasini, V.; Hostasa, J.; Goto, T.; Boulon, G.; Maksimov, R.; Gizzi, L.; Labate, L.; Toci, G.

2017-01-01

We report a review on our recent developments in Yttebium and Neodymium doped laser ceramics, along two main research lines. The first is the design and development of Yb:YAG ceramics with non uniform doping distribution, for the management of thermo-mechanical stresses and for the mitigation of ASE: layered structures have been produced by solid state reactive sintering, using different forming processes (spray drying and cold press of the homogenized powders, tape cast of the slurry); samples have been characterized and compared to FEM analysis. The second is the investigation of Lutetium based ceramics (such as mixed garnets LuYAG and Lu2O3); this interest is mainly motivated by the favorable thermal properties of these hosts under high doping. We recently obtained for the first time high efficiency laser emission from Yb doped LuYAG ceramics. The investigation on sesquioxides has been focused on Nddoped Lu2O3 ceramics, fabricated with the Spark Plasma Sintering method (SPS). We recently achieved the first laser emission above 1 W from Nd doped Lu2O3 ceramics fabricated by SPS.

Bonding of TRIP-Steel/Al2O3-(3Y)-TZP Composites and (3Y)-TZP Ceramic by a Spark Plasma Sintering (SPS) Apparatus

PubMed Central

Miriyev, Aslan; Grützner, Steffen; Krüger, Lutz; Kalabukhov, Sergey; Frage, Nachum

2016-01-01

A combination of the high damage tolerance of TRIP-steel and the extremely low thermal conductivity of partially stabilized zirconia (PSZ) can provide controlled thermal-mechanical properties to sandwich-shaped composite specimens comprising these materials. Sintering the (TRIP-steel-PSZ)/PSZ sandwich in a single step is very difficult due to differences in the sintering temperature and densification kinetics of the composite and the ceramic powders. In the present study, we successfully applied a two-step approach involving separate SPS consolidation of pure (3Y)-TZP and composites containing 20 vol % TRIP-steel, 40 vol % Al2O3 and 40 vol % (3Y)-TZP ceramic phase, and subsequent diffusion joining of both sintered components in an SPS apparatus. The microstructure and properties of the sintered and bonded specimens were characterized. No defects at the interface between the TZP and the composite after joining in the 1050–1150 °C temperature range were observed. Only limited grain growth occurred during joining, while crystallite size, hardness, shear strength and the fraction of the monoclinic phase in the TZP ceramic virtually did not change. The slight increase of the TZP layer’s fracture toughness with the joining temperature was attributed to the effect of grain size on transformation toughening. PMID:28773680

Grindability and mechanical property of ceramics

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

Guo, Changsheng; Chand, R.H.

1996-12-31

For cost-effective ceramic machining, material-specific machining methodology is needed. This requires characterizing ceramics from machining view point. In this paper, a preliminary study of the correlation between grindability and mechanical properties is reported. Results indicate that there exists complex correlations between grindability and mechanical properties such as hardness, fracture toughness and elasticity. Some ceramics of similar mechanical properties have different grindabilities, which implies that it is possible to develop ceramics of both superior mechanical properties and good grindability.

Synthesis and characterization of black ceramic pigments by recycling of two hazardous wastes

NASA Astrophysics Data System (ADS)

Du, Minxing; Du, Yi; Chen, Zhongtao; Li, Zhongfu; Yang, Kai; Lv, Xingjie; Feng, Yibing

2017-09-01

In this study, two different industrial wastes, namely vanadium tailing and leather sludge, were used as less expensive alternative raw materials for the synthesis of black ceramic pigments to be used in commercial glazes. The pigments were based on hematite structure (FexCr1-x)2O3 and prepared by the common solid-state reaction method, under optimal formulation and processing conditions. The synthesized pigments were characterized in typical ceramic glazes and ceramic tile bodies. Optimal color development was achieved when the Fe/Cr mole ratios were 2.0 with 40 wt% content of vanadium tailing at 1200 °C. The coloring properties were similar to those imparted by a commercial black pigment.

Hydrogen defects in α-Al2O3 and water weakening of sapphire and alumina ceramics between 600 and 1000°C: I. Infrared characterization of defects

USGS Publications Warehouse

Kronenberg, A.K.; Castaing, J.; Mitchell, T.E.; Kirby, S.H.

2000-01-01

Hydrogen impurities in materials influence their properties, including flow strength. α-Al2O3 single crystals and polycrystalline ceramics were annealed in supercritical water between 850 and 1025°C, under pressures in the range 1500–2000 MPa. A few specimens were further subjected to plastic deformation. Hydrogen penetration was examined using infrared absorption measurements of O–H bond vibrations, which revealed two kinds of hydrogen defects. In single crystals, defects are characterized by sharp O–H absorption bands assigned to interstitial protons. Hydrogen impurities of hydrothermally annealed ceramics and of all hydrothermally deformed specimens are characterized by broad O–H bands assigned to molecular water. The grain boundaries of hydrothermally annealed ceramics are severely damaged. The kinetics of hydrogen penetration is consistent with diffusion data.

CRACK GROWTH ANALYSIS OF SOLID OXIDE FUEL CELL ELECTROLYTES

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

S. Bandopadhyay; N. Nagabhushana

2003-10-01

Defects and Flaws control the structural and functional property of ceramics. In determining the reliability and lifetime of ceramics structures it is very important to quantify the crack growth behavior of the ceramics. In addition, because of the high variability of the strength and the relatively low toughness of ceramics, a statistical design approach is necessary. The statistical nature of the strength of ceramics is currently well recognized, and is usually accounted for by utilizing Weibull or similar statistical distributions. Design tools such as CARES using a combination of strength measurements, stress analysis, and statistics are available and reasonably wellmore » developed. These design codes also incorporate material data such as elastic constants as well as flaw distributions and time-dependent properties. The fast fracture reliability for ceramics is often different from their time-dependent reliability. Further confounding the design complexity, the time-dependent reliability varies with the environment/temperature/stress combination. Therefore, it becomes important to be able to accurately determine the behavior of ceramics under simulated application conditions to provide a better prediction of the lifetime and reliability for a given component. In the present study, Yttria stabilized Zirconia (YSZ) of 9.6 mol% Yttria composition was procured in the form of tubes of length 100 mm. The composition is of interest as tubular electrolytes for Solid Oxide Fuel Cells. Rings cut from the tubes were characterized for microstructure, phase stability, mechanical strength (Weibull modulus) and fracture mechanisms. The strength at operating condition of SOFCs (1000 C) decreased to 95 MPa as compared to room temperature strength of 230 MPa. However, the Weibull modulus remains relatively unchanged. Slow crack growth (SCG) parameter, n = 17 evaluated at room temperature in air was representative of well studied brittle materials. Based on the results, further work was planned to evaluate the strength degradation, modulus and failure in more representative environment of the SOFCs.« less

Diatomite based ceramics macro- and microscopic characterization

NASA Astrophysics Data System (ADS)

Aderdour, H.; Bentayeb, A.; Nadiri, A.; Ouammou, A.; Sangleboeuf, J.-C.; Lucas-Girot, A.; Carel, C.

2005-03-01

A Moroccan diatomite is characterized chemically and physically. Mechanical properties of ceramics prepared by sintering at different temperatures ranging from 1050 to 1350° C are studied. Compressive strength and Young modulus are determined by compression tests. Densification and evolution of the microstructure are followed by SEM and other tests.

Method for hermetic electrical connections

DOEpatents

Monroe, Saundra L [Tijeras, NM; Glass, S Jill [Albuquerque, NM; Stone, Ronnie G [Albuquerque, NM; Bond, Jamey T [Albuquerque, NM; Susan, Donald F [Albuquerque, NM

2011-12-27

A method of providing a hermetic, electrical connection between two electrical components by mating at least one metal pin in a glass-ceramic to metal seal connector to two electrical components, wherein the glass-ceramic to metal seal connector incorporates at least one metal pin encased (sealed) in a glass-ceramic material inside of a metal housing, with the glass-ceramic material made from 65-80% SiO.sub.2, 8-16% Li.sub.2O, 2-8% Al.sub.2O.sub.3, 1-5% P.sub.2O.sub.5, 1-8% K.sub.2O, 0.5-7% B.sub.2O.sub.3, and 0-5% ZnO. The connector retains hermeticity at temperatures as high as 700.degree. C. and pressures as high as 500 psi.

Correlation of compressive and shear stress with spalling of plasma-sprayed ceramic materials

NASA Technical Reports Server (NTRS)

Mullen, R. L.; Mcdonald, G.; Hendricks, R. C.; Hofle, M. M.

1983-01-01

Ceramics on metal substrates for potential use as high temperature seals or other applications are exposed to forces originating from differences in thermal expansion between the ceramic and the metal substrate. This report develops a relationship between the difference in expansion of the ceramic and the substrate, defines conditions under which shear between the ceramic and the substrate occurs, and those under which bending forces are produced in the ceramic. The off-axis effect of compression forces resulting from high temperature plastic flow of the ceramic producing buckling of the ceramic is developed. Shear is associated with the edge or boundary stresses on the component while bending is associated with the distortion of an interior region. Both modes are significant in predicting life of the ceramic. Previously announced in STAR as N83-27016

Method of making contamination-free ceramic bodies

NASA Technical Reports Server (NTRS)

Philipp, Warren H. (Inventor)

1991-01-01

Ceramic structures having high strength at temperatures above 1000 C after sintering are made by mixing ceramic powders with binder deflocculants such as guanidine salts of polymeric acids, guanidine salts of aliphatic organic carboxylic acids or guanidine alkylsulfates with the foregoing guanidine salts. The novelty of the invention appears to lie in the substitution of guanidine salts for the alkalai metal salt components or organic fatty acids of the prior art binder-deflocculant, ceramic processing aids whereby no undesirable metal contaminants are present in the final ceramic structure. Guanidine alkylsulfates also replace the Na or K alkylsulfates commonly used with binder-deflocculants in making high temperature ceramic structures.

Exploratory evaluation of ceramics for automobile thermal reactors

NASA Technical Reports Server (NTRS)

Stone, P. L.; Blankenship, C. P.

1972-01-01

An exploratory evaluation of ceramics for automobile thermal reactors was conducted. Potential ceramic materials were evaluated in several reactor designs using both engine dynamometer and vehicle road tests. Silicon carbide contained in a corrugated metal support structure exhibited the best performance lasting over 800 hours in engine dynamometer tests and over 15,000 miles (24,200 km) of vehicle road tests. Reactors containing glass-ceramic components did not perform as well as silicon carbide. But the glass-ceramics still offer good potential for reactor use. The results of this study are considered to be a reasonable demonstration of the potential use of ceramics in thermal reactors.

Towards the optimal design of an uncemented acetabular component using genetic algorithms

NASA Astrophysics Data System (ADS)

Ghosh, Rajesh; Pratihar, Dilip Kumar; Gupta, Sanjay

2015-12-01

Aseptic loosening of the acetabular component (hemispherical socket of the pelvic bone) has been mainly attributed to bone resorption and excessive generation of wear particle debris. The aim of this study was to determine optimal design parameters for the acetabular component that would minimize bone resorption and volumetric wear. Three-dimensional finite element models of intact and implanted pelvises were developed using data from computed tomography scans. A multi-objective optimization problem was formulated and solved using a genetic algorithm. A combination of suitable implant material and corresponding set of optimal thicknesses of the component was obtained from the Pareto-optimal front of solutions. The ultra-high-molecular-weight polyethylene (UHMWPE) component generated considerably greater volumetric wear but lower bone density loss compared to carbon-fibre reinforced polyetheretherketone (CFR-PEEK) and ceramic. CFR-PEEK was located in the range between ceramic and UHMWPE. Although ceramic appeared to be a viable alternative to cobalt-chromium-molybdenum alloy, CFR-PEEK seems to be the most promising alternative material.

Lightweight Ceramic Composition of Carbon Silicon Oxygen and Boron

NASA Technical Reports Server (NTRS)

Leiser, Daniel B. (Inventor); Hsu, Ming-Ta (Inventor); Chen, Timothy S. (Inventor)

1997-01-01

Lightweight, monolithic ceramics resistant to oxidation in air at high temperatures are made by impregnating a porous carbon preform with a sol which contains a mixture of tetraethoxysilane, dimethyldiethoxysilane and trimethyl borate. The sol is gelled and dried on the carbon preform to form a ceramic precursor. The precursor is pyrolyzed in an inert atmosphere to form the ceramic which is made of carbon, silicon, oxygen and boron. The carbon of the preform reacts with the dried gel during the pyrolysis to form a component of the resulting ceramic. The ceramic is of the same size, shape and form as the carbon precursor. Thus, using a porous, fibrous carbon precursor, such as a carbon felt, results in a porous, fibrous ceramic. Ceramics of the invention are useful as lightweight tiles for a reentry spacecraft.

Advanced Gas Turbine (AGT) Technology Project

NASA Technical Reports Server (NTRS)

1986-01-01

Engine testing, ceramic component fabrication and evaluation, component performance rig testing, and analytical studies comprised AGT 100 activities during the 1985 year. Ten experimental assemblies (builds) were evaluated using two engines. Accrued operating time was 120 hr of burning and 170 hr total, bringing cumulative total operating time to 395 hr, all devoid of major failures. Tests identified the generator seals as the primary working fluid leakage sources. Power transfer clutch operation was demonstrated. An alpha SiC gasifier rotor engine test resulted in blade tip failures. Recurring case vibration and shaft whip have limited gasifier shaft speeds to 84%. Ceramic components successfully engine tested now include the SiC scroll assembly, Si3N3 turbine rotor, combustor assembly, regenerator disk bulkhead, turbine vanes, piston rings, and couplings. A compressor shroud design change to reduce heat recirculation back to the inlet was executed. Ceramic components activity continues to focus on the development of state-of-the-art material strength characteristics in full-scale engine hardware. Fiber reinforced glass-ceramic composite turbine (inner) backplates were fabricated by Corning Glass Works. The BMAS/III material performed well in engine testing. Backplates of MAS material have not been engine tested.

Microwave performance of photoresist-alumina microcomposites for batch fabrication of thick polymer-based dielectric structures

NASA Astrophysics Data System (ADS)

Rashidian, Atabak; Klymyshyn, David M.; Tayfeh Aligodarz, Mohammadreza; Boerner, Martin; Mohr, Jürgen

2012-10-01

The goal of this paper is to investigate the electrical properties of photoresist-alumina microcomposites with different portions of ceramic content. Substrates of photoresist-alumina microcomposites are fabricated and a comprehensive analysis is performed to characterize their dielectric constant and dielectric loss tangent at microwave frequencies up to 40 GHz. To evaluate the performance of these materials for microwave applications, the properties of various lithographically fabricated antenna elements are examined and analysed based on the measured electrical properties. The experimental results show that the electrical properties of the photoresist composite are nonlinearly affected by ceramic content and also a minimum percentage of ceramic portion is required to improve the electrical properties of the photoresist composite. For instance, comparison of 0 wt% with 23 wt% SU8-alumina shows that no reduction is achieved for the dielectric loss tangent. Comparison of 38 wt% with 48 wt% SU8-alumina microcomposite shows that the dielectric loss tangent is improved from 0.03 to 0.01 and the dielectric constant is increased from 3.8 to 5.0 at 25 GHz. These improvements can result in superior performance for the photoresist-based microwave components.

Accelerated Testing Methodology Developed for Determining the Slow Crack Growth of Advanced Ceramics

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Gyekenyesi, John P.

1998-01-01

Constant stress-rate ("dynamic fatigue") testing has been used for several decades to characterize the slow crack growth behavior of glass and structural ceramics at both ambient and elevated temperatures. The advantage of such testing over other methods lies in its simplicity: strengths are measured in a routine manner at four or more stress rates by applying a constant displacement or loading rate. The slow crack growth parameters required for component design can be estimated from a relationship between strength and stress rate. With the proper use of preloading in constant stress-rate testing, test time can be reduced appreciably. If a preload corresponding to 50 percent of the strength is applied to the specimen prior to testing, 50 percent of the test time can be saved as long as the applied preload does not change the strength. In fact, it has been a common, empirical practice in the strength testing of ceramics or optical fibers to apply some preloading (<40 percent). The purpose of this work at the NASA Lewis Research Center is to study the effect of preloading on measured strength in order to add a theoretical foundation to the empirical practice.

Ceramic Technology For Advanced Heat Engines Project

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

Not Available

1990-12-01

Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. The objective of the project is to develop the industrial technology base required for reliable ceramicsmore » for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. This advanced materials technology is being developed in parallel and close coordination with the ongoing DOE and industry proof of concept engine development programs. To facilitate the rapid transfer of this technology to U.S. industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. Abstracts prepared for appropriate papers.« less

Slow Crack Growth and Fatigue Life Prediction of Ceramic Components Subjected to Variable Load History

NASA Technical Reports Server (NTRS)

Jadaan, Osama

2001-01-01

Present capabilities of the NASA CARES/Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code has the capability to compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth (SCG) type failure conditions CARES/Life can handle the cases of sustained and linearly increasing time-dependent loads, while for cyclic fatigue applications various types of repetitive constant amplitude loads can be accounted for. In real applications applied loads are rarely that simple, but rather vary with time in more complex ways such as, for example, engine start up, shut down, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. The objective of this paper is to demonstrate a methodology capable of predicting the time-dependent reliability of components subjected to transient thermomechanical loads that takes into account the change in material response with time. In this paper, the dominant delayed failure mechanism is assumed to be SCG. This capability has been added to the NASA CARES/Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code, which has also been modified to have the ability of interfacing with commercially available FEA codes executed for transient load histories. An example involving a ceramic exhaust valve subjected to combustion cycle loads is presented to demonstrate the viability of this methodology and the CARES/Life program.

Structural application of high strength, high temperature ceramics

NASA Technical Reports Server (NTRS)

Hall, W. B.

1982-01-01

The operation of rocket engine turbine pumps is limited by the temperature restrictions of metallic components used in the systems. Mechanical strength and stability of these metallic components decrease drastically at elevated temperatures. Ceramic materials that retain high strength at high temperatures appear to be a feasible alternate material for use in the hot end of the turbopumps. This project identified and defined the processing parameters that affected the properties of Si3N4, one of candidate ceramic materials. Apparatus was assembled and put into operation to hot press Si3N4 powders into bulk material for in house evaluation. A work statement was completed to seek outside contract services to design, manufacture, and evaluate Si3N4 components in the service environments that exists in SSME turbopumps.

Ceramic component for electrodes

DOEpatents

Marchant, David D.; Bates, J. Lambert

1980-01-01

A ceramic component suitable for preparing MHD generator electrodes having the compositional formula: Y.sub.x (Mg.sub.y Cr.sub.z).sub.w Al.sub.(1-w) O.sub.3 where x=0.9 to 1.05, y=0.02 to 0.2, z=0.8 to 1.05 and w=1.0 to 0.5. The component is resistant to the formation of hydration products in an MHD environment, has good electrical conductivity and exhibits a lower electrochemical corrosion rate than do comparable compositions of lanthanum chromite.

NDE of cylindrically symmetric components with piezofilm transducers

NASA Astrophysics Data System (ADS)

Hsu, David K.; Zhang, Zhong

PVDF polymer film transducers are presently shown to exhibit the flexibility and comformability required for inspection of components with curved surfaces. Although these transducers are less efficient than rigid ceramic ones, and are less accurately matched to the acoustic impedance of metals as well as ceramic transducers, their advantages are presently shown to outweigh their disadvantages in some applications involving tube and rod shaped components. Interface measurements of a Zr/Zircalloy-2 tube allowed the detailed evaluation of weakly reflecting interfaces.

Solution properties and spectroscopic characterization of polymeric precursors to SiNCB and BN ceramic materials

NASA Astrophysics Data System (ADS)

Cortez, E.; Remsen, E.; Chlanda, V.; Wideman, T.; Zank, G.; Carrol, P.; Sneddon, L.

1998-06-01

Boron Nitride, BN, and composite SiNCB ceramic fibers are important structural materials because of their excellent thermal and oxidative stabilities. Consequently, polymeric materials as precursors to ceramic composites are receiving increasing attention. Characterization of these materials requires the ability to evaluate simultaneous molecular weight and compositional heterogeneity within the polymer. Size exclusion chromatography equipped with viscometric and refractive index detection as well as coupled to a LC-transform device for infrared absorption analysis has been employed to examine these heterogeneities. Using these combined approaches, the solution properties and the relative amounts of individual functional groups distributed through the molecular weight distribution of SiNCB and BN polymeric precursors were characterized.

Internal coating of zirconia restoration with silica-based ceramic improves bonding of resin cement to dental zirconia ceramic.

PubMed

Kitayama, Shuzo; Nikaido, Toru; Ikeda, Masaomi; Alireza, Sadr; Miura, Hiroyuki; Tagami, Junji

2010-01-01

Resin bonding to zirconia ceramic cannot be established by standard methods that are utilized for conventional silica-based dental ceramics. This study was aimed to examine the tensile bond strength of resin cement to zirconia ceramic using a new laboratory technique. Sixty-four zirconia ceramic specimens were air-abraded using Al2O3 particles and divided into two groups; the control group with no pretreatment (Control), and the group pretreated using the internal coating technique (INT), in which the surface of the zirconia specimens were thinly coated by fusing silica-based ceramic and air-abraded in the same manner. The specimens in each group were further divided into two subgroups according to the silane coupling agents applied; a mixture of dentin primer/silane coupling agent (Clearfil SE Bond Primer/Porcelain Bond Activator) or a newly developed single-component silane coupling agent (Clearfil Ceramic Primer). After bonding with dual-cured resin cement (Panavia F 2.0), they were stored in water for 24 h and half of them were additionally subjected to thermal cycling. The tensile bond strengths were tested using a universal testing machine. ANOVAs revealed significant influence of ceramic surface pretreatment (p<0.001), silane coupling agent (p<0.001) and thermal cycling (p<0.001); the INT coating technique significantly increased the bond strengths of resin cement to zirconia ceramic, whereas thermal cycling significantly decreased the bond strengths. The use of a single-component silane coupling agent demonstrated significantly higher bond strengths than that of a mixture of dentin primer/silane coupling agent. The internal coating of zirconia dental restorations with silica-based ceramic followed by silanization may be indicated in order to achieve better bonding for the clinical success.

Continuous fiber ceramic matrix composites for heat engine components

NASA Technical Reports Server (NTRS)

Tripp, David E.

1988-01-01

High strength at elevated temperatures, low density, resistance to wear, and abundance of nonstrategic raw materials make structural ceramics attractive for advanced heat engine applications. Unfortunately, ceramics have a low fracture toughness and fail catastrophically because of overload, impact, and contact stresses. Ceramic matrix composites provide the means to achieve improved fracture toughness while retaining desirable characteristics, such as high strength and low density. Materials scientists and engineers are trying to develop the ideal fibers and matrices to achieve the optimum ceramic matrix composite properties. A need exists for the development of failure models for the design of ceramic matrix composite heat engine components. Phenomenological failure models are currently the most frequently used in industry, but they are deterministic and do not adequately describe ceramic matrix composite behavior. Semi-empirical models were proposed, which relate the failure of notched composite laminates to the stress a characteristic distance away from the notch. Shear lag models describe composite failure modes at the micromechanics level. The enhanced matrix cracking stress occurs at the same applied stress level predicted by the two models of steady state cracking. Finally, statistical models take into consideration the distribution in composite failure strength. The intent is to develop these models into computer algorithms for the failure analysis of ceramic matrix composites under monotonically increasing loads. The algorithms will be included in a postprocessor to general purpose finite element programs.

AGT (Advanced Gas Turbine) technology project

NASA Technical Reports Server (NTRS)

1988-01-01

An overall summary documentation is provided for the Advanced Gas Turbine Technology Project conducted by the Allison Gas Turbine Division of General Motors. This advanced, high risk work was initiated in October 1979 under charter from the U.S. Congress to promote an engine for transportation that would provide an alternate to reciprocating spark ignition (SI) engines for the U.S. automotive industry and simultaneously establish the feasibility of advanced ceramic materials for hot section components to be used in an automotive gas turbine. As this program evolved, dictates of available funding, Government charter, and technical developments caused program emphases to focus on the development and demonstration of the ceramic turbine hot section and away from the development of engine and powertrain technologies and subsequent vehicular demonstrations. Program technical performance concluded in June 1987. The AGT 100 program successfully achieved project objectives with significant technology advances. Specific AGT 100 program achievements are: (1) Ceramic component feasibility for use in gas turbine engines has been demonstrated; (2) A new, 100 hp engine was designed, fabricated, and tested for 572 hour at operating temperatures to 2200 F, uncooled; (3) Statistical design methodology has been applied and correlated to experimental data acquired from over 5500 hour of rig and engine testing; (4) Ceramic component processing capability has progressed from a rudimentary level able to fabricate simple parts to a sophisticated level able to provide complex geometries such as rotors and scrolls; (5) Required improvements for monolithic and composite ceramic gas turbine components to meet automotive reliability, performance, and cost goals have been identified; (6) The combustor design demonstrated lower emissions than 1986 Federal Standards on methanol, JP-5, and diesel fuel. Thus, the potential for meeting emission standards and multifuel capability has been initiated; (7) Small turbine engine aerodynamic and mechanical design capability has been initiated; and (8) An infrastructure of manpower, facilities, materials, and fabrication capabilities has been established which is available for continued development of ceramic component technology in gas turbine and other heat engines.

Creep Life Prediction of Ceramic Components Using the Finite Element Based Integrated Design Program (CARES/Creep)

NASA Technical Reports Server (NTRS)

Jadaan, Osama M.; Powers, Lynn M.; Gyekenyesi, John P.

1997-01-01

The desirable properties of ceramics at high temperatures have generated interest in their use for structural applications such as in advanced turbine systems. Design lives for such systems can exceed 10,000 hours. Such long life requirements necessitate subjecting the components to relatively low stresses. The combination of high temperatures and low stresses typically places failure for monolithic ceramics in the creep regime. The objective of this work is to present a design methodology for predicting the lifetimes of structural components subjected to multiaxial creep loading. This methodology utilizes commercially available finite element packages and takes into account the time varying creep stress distributions (stress relaxation). In this methodology, the creep life of a component is divided into short time steps, during which, the stress and strain distributions are assumed constant. The damage, D, is calculated for each time step based on a modified Monkman-Grant creep rupture criterion. For components subjected to predominantly tensile loading, failure is assumed to occur when the normalized accumulated damage at any point in the component is greater than or equal to unity.

Considerations on Dop (Depth Of Penetration) Test for Evaluation of Ceramics Materials Used in Ballistic Protection

NASA Astrophysics Data System (ADS)

Popa, Ioan-Dan; Dobriţa, Florin

2017-12-01

Tremendous amount of funds and other resorces were invested in studying the response of ceramic materials under ballistic impact, the main goal being to find a way to increase the protection of soldiers and the vehicles used in the modern battlespace. Using of ceramic materials especially carbon based (carbides), nitrogen based (nitrides) and oxygen based (oxides) ceramics in order to increase the protection level of ballistic equipment could be, sometimes, a big challenge when trying to use the proper test in order to evaluate and compare their performances. The role of the tests is to provide a better understanding of their response in different situations and, as a consequence, to make them more efficient as armour components through future improvements. The paper presents shortly the main tests which are used and eventually standardised for evaluating the ballistic behaviour of the ceramics and other armour components, with a special focus to DOP (Depth of Penetration) Tests.

Influence of Ceramic Powder Size on Process of Cermet Coating Formation by Cold Spray

NASA Astrophysics Data System (ADS)

Sova, A.; Papyrin, A.; Smurov, I.

2009-12-01

Influence of the ceramic particle size on the process of formation of cermet coatings by cold spray is experimentally studied. A specially developed nozzle with separate injection of ceramic and metal powders into the gas stream is used in the experiments. The results obtained demonstrate that fine ceramic powders (Al2O3, SiC) produce a strong activation effect on the process of spraying soft metal (Al, Cu) and increase deposition efficiency of the metal component of the mixture compared to the pure metal spraying. At the same time, coarse ceramic powder produces a strong erosion effect that considerably reduces coating mass growth and deposition efficiency of the metal component. It is experimentally shown that the addition of fine hard powder to soft metals as Al and Cu allows to significantly reduce the “critical” temperature (the minimum gas stagnation temperature at which a nonzero particle deposition is observed) for spraying these metals.

A sputtered zirconia primer for improved thermal shock resistance of plasma sprayed ceramic turbine seals

NASA Technical Reports Server (NTRS)

Bill, R. C.; Sovey, J.; Allen, G. P.

1981-01-01

The development of plasma-sprayed yttria stabilized zirconia (YSZ) ceramic turbine blade tip seal components is discussed. The YSZ layers are quite thick (0.040 to 0.090 in.). The service potential of seal components with such thick ceramic layers is cyclic thermal shock limited. The most usual failure mode is ceramic layer delamination at or very near the interface between the plasma sprayed YSZ layer and the NiCrAlY bondcoat. Deposition of a thin RF sputtered YSZ primer to the bondcoat prior to deposition of the thick plasma sprayed YSZ layer was found to reduce laminar cracking in cyclic thermal shock testing. The cyclic thermal shock life of one ceramic seal design was increased by a factor of 5 to 6 when the sputtered YSZ primer was incorporated. A model based on thermal response of plasma sprayed YSZ particles impinging on the bondcoat surface with and without the sputtered YSZ primer provides a basis for understanding the function of the primer.

Chemistry of electronic ceramic materials. Proceedings of the International Conference on the Chemistry of Electronic Ceramic Materials

NASA Technical Reports Server (NTRS)

Davies, P. K.; Roth, R. S.

1991-01-01

The conference was held at Jackson Hole, Wyoming from August 17 to 22, 1990, and in an attempt to maximize the development of this rapidly moving, multidisciplinary field, this conference brought together major national and international researchers to bridge the gap between those primarily interested in the pure chemistry of inorganic solids and those interested in the physical and electronic properties of ceramics. With the many major discoveries that have occurred over the last decade, one of the goals of this meeting was to evaluate the current understanding of the chemistry of electronic ceramic materials, and to assess the state of a field that has become one of the most important areas of advanced materials research. The topics covered include: crystal chemistry; dielectric ceramics; low temperature synthesis and characterization; solid state synthesis and characterization; surface chemistry; superconductors; theory and modeling.

Fabrication and characterization of biomimetic ceramic/polymer composite materials for dental restoration.

PubMed

Petrini, Morena; Ferrante, Maurizio; Su, Bo

2013-04-01

Conventional dental composites with randomly dispersed inorganic particles within a polymer matrix fail to recapitulate the aligned and anisotropic structure of the dentin and enamel. The aim of the study was to produce a biomimetic composite consisting of a ceramic preform with graded and continuously aligned open pores, infiltrated with epoxy resin. The freeze casting technique was used to obtain the hierarchically structured architecture of the ceramic preforms. Optical and scanning electron microscopy (SEM) and differential thermal analysis and thermogravimetry (TG-DTA) were used to characterize the samples. Three point bending test and compression test were also performed. All analysis confirmed that the biomimetic composite was characterized by a multi-level hierarchical structure along the freezing direction. In the bottom layers close to the cooling plate (up to 2mm thick), a randomly packed ceramic with closed pores were formed, which resulted in incomplete infiltration with resin and resultant poor mechanical propertiesof the composite. Above 2mm, all ceramic samples showed an aligned structure with an increasing lamellae spacing (wavelength) and a decreasing wall thickness. Mechanical tests showed that the properties of the composites made from ceramic preforms above 2mm from cooling plate are similar to those of the dentin. The fabrication processing reported in this work offers a viable route for the fabrication of biomimetic composites, which could be potentially used in a range of dental restorations to compete with the current dental composites and ceramics. Copyright © 2012 Academy of Dental Materials. All rights reserved.

Intraoperative impaction of total knee replacements: an explicit finite-element-analysis of principal stresses in ceramic vs. cobalt-chromium femoral components.

PubMed

Kluess, Daniel; Mittelmeier, Wolfram; Bader, Rainer

2010-12-01

In connection with technological advances in the manufacturing of medical ceramics, a newly developed ceramic femoral component was introduced in total knee arthroplasty. We generated an explicit finite-element-model to calculate the stresses developed under the highly dynamic intraoperative impaction with regard to cobalt-chromium and ceramic implant material as well as application of a silicone cover in order to reduce stress. The impaction was calculated with the hammer hitting the backside of the impactor at previously measured initial velocities. Subsequently the impactor, consisting of a steel handhold and a polyoxymethylene head, hit the femoral component. Instead of modelling femoral bone, the implant was mounted on four spring elements with spring constants previously determined in an experimental impaction model. The maximum principal stresses in the implants were evaluated at 8000 increments during the first 4 ms of impact. The ceramic implant showed principal stresses 10% to 48% higher than the cobalt chromium femoral component. The simulation of a 5mm thick silicone layer between the impactor and the femoral component showed a strong decrease of vibration resulting in a reduction of 54% to 68% of the maximum stress amounts. The calculated amounts of principal stress were beneath the ultimate bending strengths of each material. Based on the results, intraoperative fracture of femoral components in total knee replacement may not be caused solely by impaction, but also by contributing geometrical factors such as inadequate preparation of the distal femur. In order to minimize the influence of impaction related stress peaks we recommend limiting the velocity as well as the weight of the impaction hammer when inserting femoral components. The silicone cover seems to deliver a strong decrease of implant stress and should be considered in surgery technique in the future. Copyright © 2010 Elsevier Ltd. All rights reserved.

Additive Manufacturing of Metallic and Ceramic Components by the Material Extrusion of Highly-Filled Polymers: A Review and Future Perspectives

PubMed Central

Cano, Santiago

2018-01-01

Additive manufacturing (AM) is the fabrication of real three-dimensional objects from metals, ceramics, or plastics by adding material, usually as layers. There are several variants of AM; among them material extrusion (ME) is one of the most versatile and widely used. In MEAM, molten or viscous materials are pushed through an orifice and are selectively deposited as strands to form stacked layers and subsequently a three-dimensional object. The commonly used materials for MEAM are thermoplastic polymers and particulate composites; however, recently innovative formulations of highly-filled polymers (HP) with metals or ceramics have also been made available. MEAM with HP is an indirect process, which uses sacrificial polymeric binders to shape metallic and ceramic components. After removing the binder, the powder particles are fused together in a conventional sintering step. In this review the different types of MEAM techniques and relevant industrial approaches for the fabrication of metallic and ceramic components are described. The composition of certain HP binder systems and powders are presented; the methods of compounding and filament making HP are explained; the stages of shaping, debinding, and sintering are discussed; and finally a comparison of the parts produced via MEAM-HP with those produced via other manufacturing techniques is presented. PMID:29783705

Additive Manufacturing of Metallic and Ceramic Components by the Material Extrusion of Highly-Filled Polymers: A Review and Future Perspectives.

PubMed

Gonzalez-Gutierrez, Joamin; Cano, Santiago; Schuschnigg, Stephan; Kukla, Christian; Sapkota, Janak; Holzer, Clemens

2018-05-18

Additive manufacturing (AM) is the fabrication of real three-dimensional objects from metals, ceramics, or plastics by adding material, usually as layers. There are several variants of AM; among them material extrusion (ME) is one of the most versatile and widely used. In MEAM, molten or viscous materials are pushed through an orifice and are selectively deposited as strands to form stacked layers and subsequently a three-dimensional object. The commonly used materials for MEAM are thermoplastic polymers and particulate composites; however, recently innovative formulations of highly-filled polymers (HP) with metals or ceramics have also been made available. MEAM with HP is an indirect process, which uses sacrificial polymeric binders to shape metallic and ceramic components. After removing the binder, the powder particles are fused together in a conventional sintering step. In this review the different types of MEAM techniques and relevant industrial approaches for the fabrication of metallic and ceramic components are described. The composition of certain HP binder systems and powders are presented; the methods of compounding and filament making HP are explained; the stages of shaping, debinding, and sintering are discussed; and finally a comparison of the parts produced via MEAM-HP with those produced via other manufacturing techniques is presented.

Environmental Barrier Coatings for Ceramics and Ceramic Composites

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Fox, Dennis; Eldridge, Jeffrey; Robinson, R. Craig; Bansal, Narottam

2004-01-01

One key factor that limits the performance of current gas turbine engines is the temperature capability of hot section structural components. Silicon-based ceramics, such as SiC/SiC composites and monolithic Si3N4, are leading candidates to replace superalloy hot section components in the next generation gas turbine engines due to their excellent high temperature properties. A major stumbling block to realizing Si-based ceramic hot section components is the recession of Si-based ceramics in combustion environments due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is the most promising approach to preventing the recession. Current EBCs are based on silicon, mullite (3A12O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit the durability and temperature capability of current EBCs. Research is underway to develop EBCs with longer life and enhanced temperature capability. Understanding key issues affecting the performance of current EBCs is necessary for successful development of advanced EBCs. These issues include stress, chemical compatibility, adherence, and water vapor stability. Factors that affect stress are thermal expansion mismatch, phase stability, chemical stability, elastic modulus, etc. The current understanding on these issues will be discussed.

Emerging Applications of Ceramic and Metal Matrix Composites

NASA Astrophysics Data System (ADS)

Krishnamoorthy, Divya; Ramolina, Dheeyana; Sandou, Sherleena

2012-07-01

Almost 500 papers were presented during the 43 sessions of the 27th Annual Cocoa Beach Conference & Exposition on Advanced Ceramics & Composites, which was organized by the Engineering Ceramics Division of the American Ceramic Society and sponsored by several federal agencies: NASA Glenn Research Center, the Army Research Office, the Department of Energy, and the Air Force Office of Scientific Research. Many of these papers focused on composites, both ceramic and metal matrix, and discussed mechanical behavior, design, fibers/interfaces, processing, and applications. Potential applications under development include components for armor, nuclear energy, and automobiles. A few of these applications have reached commercialization.

Design and evaluation of experimental ceramic automobile thermal reactors

NASA Technical Reports Server (NTRS)

Stone, P. L.; Blankenship, C. P.

1974-01-01

The paper summarizes the results obtained in an exploratory evaluation of ceramics for automobile thermal reactors. Candidate ceramic materials were evaluated in several reactor designs using both engine dynamometer and vehicle road tests. Silicon carbide contained in a corrugated metal support structure exhibited the best performance, lasting 1100 hours in engine dynamometer tests and for more than 38,600 kilimeters (24,000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs.

Design and evaluation of experimental ceramic automobile thermal reactors

NASA Technical Reports Server (NTRS)

Stone, P. L.; Blankenship, C. P.

1974-01-01

The results obtained in an exploratory evaluation of ceramics for automobile thermal reactors are summarized. Candidate ceramic materials were evaluated in several reactor designs by using both engine-dynamometer and vehicle road tests. Silicon carbide contained in a corrugated-metal support structure exhibited the best performance, lasting 1100 hr in engine-dynamometer tests and more than 38,600 km (24000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as those containing silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs.

Making Ceramic Components For Advanced Aircraft Engines

NASA Technical Reports Server (NTRS)

Franklin, J. E.; Ezis, A.

1994-01-01

Lightweight, oxidation-resistant silicon nitride components containing intricate internal cooling and hydraulic passages and capable of withstanding high operating temperatures made by ceramic-platelet technology. Used to fabricate silicon nitride test articles of two types: components of methane-cooled regenerator for air turbo ramjet engine and components of bipropellant injector for rocket engine. Procedures for development of more complex and intricate components established. Technology has commercial utility in automotive, aircraft, and environmental industries for manufacture of high-temperature components for use in regeneration of fuels, treatment of emissions, high-temperature combustion devices, and application in which other high-temperature and/or lightweight components needed. Potential use in fabrication of combustors and high-temperature acoustic panels for suppression of noise in future high-speed aircraft.

Feature selection for neural network based defect classification of ceramic components using high frequency ultrasound.

PubMed

Kesharaju, Manasa; Nagarajah, Romesh

2015-09-01

The motivation for this research stems from a need for providing a non-destructive testing method capable of detecting and locating any defects and microstructural variations within armour ceramic components before issuing them to the soldiers who rely on them for their survival. The development of an automated ultrasonic inspection based classification system would make possible the checking of each ceramic component and immediately alert the operator about the presence of defects. Generally, in many classification problems a choice of features or dimensionality reduction is significant and simultaneously very difficult, as a substantial computational effort is required to evaluate possible feature subsets. In this research, a combination of artificial neural networks and genetic algorithms are used to optimize the feature subset used in classification of various defects in reaction-sintered silicon carbide ceramic components. Initially wavelet based feature extraction is implemented from the region of interest. An Artificial Neural Network classifier is employed to evaluate the performance of these features. Genetic Algorithm based feature selection is performed. Principal Component Analysis is a popular technique used for feature selection and is compared with the genetic algorithm based technique in terms of classification accuracy and selection of optimal number of features. The experimental results confirm that features identified by Principal Component Analysis lead to improved performance in terms of classification percentage with 96% than Genetic algorithm with 94%. Copyright © 2015 Elsevier B.V. All rights reserved.

Research into properties of wear resistant ceramic metal plasma coatings

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

In-situ formation of multiphase deposited thermal barrier coatings

DOEpatents

Subramanian, Ramesh

2004-01-13

A multiphase ceramic thermal barrier coating is provided. The coating is adapted for use in high temperature applications in excess of about 1200.degree. C., for coating superalloy components of a combustion turbine engine. The coating comprises a ceramic single or two oxide base layer disposed on the substrate surface; and a ceramic oxide reaction product material disposed on the base layer, the reaction product comprising the reaction product of the base layer with a ceramic single or two oxide overlay layer.

Property Screening and Evaluation of Ceramic Turbine Materials

DTIC Science & Technology

1984-04-01

Unless otherwise indicated, the upper and lower spans were 0.875 and 1.750 in., respectively. For room-temperature tests, a stainless steel fixture...Silicon Nitride High Temperature Properties Silicon Carbide Silicon Ceramics Transformation-Toughened Zirconia Structural Ceramics Mechanical Properties...3ilicon carbide and silicon nitride, that have potential as structural components in"advanced gas turbine engines, were evaluated. Thermal and

Portable automated imaging in complex ceramics with a microwave interference scanning system

NASA Astrophysics Data System (ADS)

Goitia, Ryan M.; Schmidt, Karl F.; Little, Jack R.; Ellingson, William A.; Green, William; Franks, Lisa P.

2013-01-01

An improved portable microwave interferometry system has been automated to permit rapid examination of components with minimal operator attendance. Functionalities include stereo and multiplexed, frequency-modulated at multiple frequencies, producing layered volumetric images of complex ceramic structures. The technique has been used to image composite ceramic armor and ceramic matrix composite components, as well as other complex dielectric materials. The system utilizes Evisive Scan microwave interference scanning technique. Validation tests include artificial and in-service damage of ceramic armor, surrogates and ceramic matrix composite samples. Validation techniques include micro-focus x-ray and computed tomography imaging. The microwave interference scanning technique has demonstrated detection of cracks, interior laminar features and variations in material properties such as density. The image yields depth information through phase angle manipulation, and shows extent of feature and relative dielectric property information. It requires access to only one surface, and no coupling medium. Data are not affected by separation of layers of dielectric material, such as outer over-wrap. Test panels were provided by the US Army Research Laboratory, and the US Army Tank Automotive Research, Development and Engineering Center (TARDEC), who with the US Air Force Research Laboratory have supported this work.

CARES - CERAMICS ANALYSIS AND RELIABILITY EVALUATION OF STRUCTURES

NASA Technical Reports Server (NTRS)

Nemeth, N. N.

1994-01-01

The beneficial properties of structural ceramics include their high-temperature strength, light weight, hardness, and corrosion and oxidation resistance. For advanced heat engines, ceramics have demonstrated functional abilities at temperatures well beyond the operational limits of metals. This is offset by the fact that ceramic materials tend to be brittle. When a load is applied, their lack of significant plastic deformation causes the material to crack at microscopic flaws, destroying the component. CARES calculates the fast-fracture reliability or failure probability of macroscopically isotropic ceramic components. These components may be subjected to complex thermomechanical loadings. The program uses results from a commercial structural analysis program (MSC/NASTRAN or ANSYS) to evaluate component reliability due to inherent surface and/or volume type flaws. A multiple material capability allows the finite element model reliability to be a function of many different ceramic material statistical characterizations. The reliability analysis uses element stress, temperature, area, and volume output, which are obtained from two dimensional shell and three dimensional solid isoparametric or axisymmetric finite elements. CARES utilizes the Batdorf model and the two-parameter Weibull cumulative distribution function to describe the effects of multi-axial stress states on material strength. The shear-sensitive Batdorf model requires a user-selected flaw geometry and a mixed-mode fracture criterion. Flaws intersecting the surface and imperfections embedded in the volume can be modeled. The total strain energy release rate theory is used as a mixed mode fracture criterion for co-planar crack extension. Out-of-plane crack extension criteria are approximated by a simple equation with a semi-empirical constant that can model the maximum tangential stress theory, the minimum strain energy density criterion, the maximum strain energy release rate theory, or experimental results. For comparison, Griffith's maximum tensile stress theory, the principle of independent action, and the Weibull normal stress averaging models are also included. Weibull material strength parameters, the Batdorf crack density coefficient, and other related statistical quantities are estimated from four-point bend bar or uniform uniaxial tensile specimen fracture strength data. Parameter estimation can be performed for single or multiple failure modes by using the least-squares analysis or the maximum likelihood method. A more limited program, CARES/PC (COSMIC number LEW-15248) runs on a personal computer and estimates ceramic material properties from three-point bend bar data. CARES/PC does not perform fast fracture reliability estimation. CARES is written in FORTRAN 77 and has been implemented on DEC VAX series computers under VMS and on IBM 370 series computers under VM/CMS. On a VAX, CARES requires 10Mb of main memory. Five MSC/NASTRAN example problems and two ANSYS example problems are provided. There are two versions of CARES supplied on the distribution tape, CARES1 and CARES2. CARES2 contains sub-elements and CARES1 does not. CARES is available on a 9-track 1600 BPI VAX FILES-11 format magnetic tape (standard media) or in VAX BACKUP format on a TK50 tape cartridge. The program requires a FORTRAN 77 compiler and about 12Mb memory. CARES was developed in 1990. DEC, VAX and VMS are trademarks of Digital Equipment Corporation. IBM 370 is a trademark of International Business Machines. MSC/NASTRAN is a trademark of MacNeal-Schwendler Corporation. ANSYS is a trademark of Swanson Analysis Systems, Inc.

Deposition efficiency optimization in cold spraying of metal-ceramic powder mixtures

NASA Astrophysics Data System (ADS)

Klinkov, S. V.; Kosarev, V. F.

2017-10-01

In the present paper, results of optimization of the cold spray deposition process of a metal-ceramic powder mixture involving impacts of ceramic particles onto coating surface are reported. In the optimization study, a two-probability model was used to take into account the surface activation induced by the ceramic component of the mixture. The dependence of mixture deposition efficiency on the concentration and size of ceramic particles was analysed to identify the ranges of both parameters in which the effect due to ceramic particles on the mixture deposition efficiency was positive. The dependences of the optimum size and concentration of ceramic particles, and also the maximum gain in deposition efficiency, on the probability of adhesion of metal particles to non-activated coating surface were obtained.

Development of Sensors for Ceramic Components in Advanced Propulsion Systems. Phase 2; Temperature Sensor Systems Evaluation

NASA Technical Reports Server (NTRS)

Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

1994-01-01

The 'development of sensors for ceramic components in advanced propulsion systems' program is divided into two phases. The objectives of Phase 1 were to analyze, evaluate and recommend sensor concepts for the measurement of surface temperature, strain and heat flux on ceramic components for advanced propulsion systems. The results of this effort were previously published in NASA CR-182111. As a result of Phase 1, three approaches were recommended for further development: pyrometry, thin-film sensors, and thermographic phosphors. The objective of Phase 2 were to fabricate and conduct laboratory demonstration tests of these systems. Six materials, mutually agreed upon by NASA and Pratt & Whitney, were investigated under this program. This report summarizes the Phase 2 effort and provides conclusions and recommendations for each of the categories evaluated.

High concentrations of heavy metals in PM from ceramic factories of Southern Spain

NASA Astrophysics Data System (ADS)

Sánchez de la Campa, Ana M.; de la Rosa, Jesús D.; González-Castanedo, Yolanda; Fernández-Camacho, Rocío; Alastuey, Andrés; Querol, Xavier; Pio, Casimiro

2010-06-01

In this study, physicochemical characterization of Atmospheric Particulate Matter (PM) was performed in an urban-industrial site background (Bailén, Southern Spain), highly influenced by the impact of emission plumes from ceramic factories. This area is considered one of the towns with the highest PM 10 levels and average SO 2 concentration in Spain. A three stages methodology was used: 1) real-time measurements of levels of PM 10 and gaseous pollutants, and sampling of PM; 2) chemical characterization using ICP-MS, ICP-OES, CI and TOT, and source apportionment analysis (receptor modelling) of PM; and 3) chemical characterization of emission plumes derived from representative factories. High ambient air concentrations were found for most major components and trace elements compared with other industrialized towns in Spain. V and Ni are considered fingerprints of PM derived from the emissions of brick factories in this area, and were shown to be of particular interest. This highlights the high V and Ni concentrations in PM 10 (122 ngV/m 3 and 23.4 ngNi/m 3), with Ni exceeding the 2013 annual target value for the European Directive 2004/107/EC (20 ng/m 3). The methodology of this work can be used by Government departments responsible for Environment and Epidemiology in planning control strategies for improving air quality.

An Investigation of SiC/SiC Woven Composite Under Monotonic and Cyclic Loading

NASA Technical Reports Server (NTRS)

Lang, J.; Sankar, J.; Kelkar, A. D.; Bhatt, R. T.; Singh, M.; Lua, J.

1997-01-01

The desirable properties in ceramic matrix composites (CMCs), such as high temperature strength, corrosion resistance, high toughness, low density, or good creep resistance have led to increased use of CMCs in high-speed engine structural components and structures that operate in extreme temperature and hostile aero-thermo-chemical environments. Ceramic matrix composites have been chosen for turbine material in the design of 21 st-century civil propulsion systems to achieve high fuel economy, improved reliability, extended life, and reduced cost. Most commercial CMCs are manufactured using a chemical vapor infiltration (CVI) process. However, a lower cost fabrication known as melt-infiltration process is also providing CMCs marked for use in hot sections of high-speed civil transports. The scope of this paper is to report on the material and mechanical characterization of the CMCs subjected to this process and to predict the behavior through an analytical model. An investigation of the SiC/SiC 8-harness woven composite is ongoing and its tensile strength and fatigue behavior is being characterized for room and elevated temperatures. The investigation is being conducted at below and above the matrix cracking stress once these parameters are identified. Fractography and light microscopy results are being studied to characterize the failure modes resulting from pure uniaxial loading. A numerical model is also being developed to predict the laminate properties by using the constituent material properties and tow undulation.

Ceramics in nuclear waste management

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

Chikalla, T D; Mendel, J E

1979-05-01

Seventy-three papers are included, arranged under the following section headings: national programs for the disposal of radioactive wastes, waste from stability and characterization, glass processing, ceramic processing, ceramic and glass processing, leaching of waste materials, properties of nuclear waste forms, and immobilization of special radioactive wastes. Separate abstracts were prepared for all the papers. (DLC)

Ceramic Surface Treatment with a Single-component Primer: Resin Adhesion to Glass Ceramics.

PubMed

Prado, Mayara; Prochnow, Catina; Marchionatti, Ana Maria Estivalete; Baldissara, Paolo; Valandro, Luiz Felipe; Wandscher, Vinicius Felipe

2018-04-19

To evaluate the microshear bond strength (μSBS) of composite cement bonded to two machined glass ceramics and its durability, comparing conventional surface conditioning (hydrofluoric acid + silane) to a one-step primer (Monobond Etch & Prime). Machined slices of lithium disilicate ceramic (LDC) (IPS e.max CAD) and feldspathic ceramic (FC) (VITA Mark II) glass ceramics were divided into two groups (n = 10) according to two factors: 1. surface treatment: HF+S (ca 5% hydrofluoric acid [IPS Ceramic Etching GEL] + silane coupling agent [SIL; Monobond Plus]) or MEP (single-component ceramic conditioner; Monobond Etch & Prime); 2. storage condition: baseline (without aging; tested 24 h after cementing) or aged (70 days of water storage + 12,000 thermal cycles). Composite cement (Multilink Automix, Ivoclar Vivadent) was applied to starch matrices on the treated ceramic surfaces and photoactivated. A μSBS test was performed (0.5 mm/min) and the failure pattern was determined. Contact angle and micromorphological analyses were also performed. Data were analyzed with Student's t-test (α = 5%). For both ceramic materials, HF+S resulted in higher mean μSBS (MPa) at baseline (LDC: HF+S 21.2 ± 2.2 > MEP 10.4 ± 2.4; FC: HF+S 19.6 ± 4.3 > MEP 13.5 ± 5.4) and after aging (LDC: HF+S 14.64 ± 2.31 > MEP 9 ± 3.4; FC HF+S: 14.73 ± 3.33 > MEP 11.1 ± 3.3). HF+S resulted in a statistically significant decrease in mean μSBS after aging (p = 0.0001), while MEP yielded no significant reduction. The main failure type was adhesive between composite cement and ceramic. HF+S resuted in the lowest contact angle. Hydrofluoric acid + silane resulted in higher mean μSBS than Monobond Etch & Prime for both ceramics; however, Monobond Etch & Prime had stable bonding after aging.

Joining of Silicon Carbide-Based Ceramics by Reaction Forming Method

NASA Technical Reports Server (NTRS)

Singh, M.; Kiser, J. D.

1997-01-01

Recently, there has been a surge of interest in the development and testing of silicon-based ceramics and composite components for a number of aerospace and ground based systems. The designs often require fabrication of complex shaped parts which can be quite expensive. One attractive way of achieving this goal is to build up complex shapes by joining together geometrically simple shapes. However, the joints should have good mechanical strength and environmental stability comparable to the bulk materials. These joints should also be able to maintain their structural integrity at high temperatures. In addition, the joining technique should be practical, reliable, and affordable. Thus, joining has been recognized as one of the enabling technologies for the successful utilization of silicon carbide based ceramic components in high temperature applications. Overviews of various joining techniques, i.e., mechanical fastening, adhesive bonding, welding, brazing, and soldering have been provided in recent publications. The majority of the techniques used today are based on the joining of monolithic ceramics with metals either by diffusion bonding, metal brazing, brazing with oxides and oxynitrides, or diffusion welding. These techniques need either very high temperatures for processing or hot pressing (high pressures). The joints produced by these techniques have different thermal expansion coefficients than the ceramic materials, which creates a stress concentration in the joint area. The use temperatures for these joints are around 700 C. Ceramic joint interlayers have been developed as a means of obtaining high temperature joints. These joint interlayers have been produced via pre-ceramic polymers, in-situ displacement reactions, and reaction bonding techniques. Joints produced by the pre-ceramic polymer approach exhibit a large amounts of porosity and poor mechanical properties. On the other hand, hot pressing or high pressures are needed for in-situ displacement reactions and reaction bonding techniques. Due to the equipment required, these techniques are impractical for joining large or complex shaped components.

Numerical Simulation of Sintering Process in Ceramic Powder Injection Moulded Components

NASA Astrophysics Data System (ADS)

Song, J.; Barriere, T.; Liu, B.; Gelin, J. C.

2007-05-01

A phenomenological model based on viscoplastic constitutive law is presented to describe the sintering process of ceramic components obtained by powder injection moulding. The parameters entering in the model are identified through sintering experiments in dilatometer with the proposed optimization method. The finite element simulations are carried out to predict the density variations and dimensional changes of the components during sintering. A simulation example on the sintering process of hip implant in alumina has been conducted. The simulation results have been compared with the experimental ones. A good agreement is obtained.

Reliability of hybrid microcircuit discrete components

NASA Technical Reports Server (NTRS)

Allen, R. V.

1972-01-01

Data accumulated during 4 years of research and evaluation of ceramic chip capacitors, ceramic carrier mounted active devices, beam-lead transistors, and chip resistors are presented. Life and temperature coefficient test data, and optical and scanning electron microscope photographs of device failures are presented and the failure modes are described. Particular interest is given to discrete component qualification, power burn-in, and procedures for testing and screening discrete components. Burn-in requirements and test data will be given in support of 100 percent burn-in policy on all NASA flight programs.

Emittance and absorptance of NASA ceramic thermal barrier coating system. [for turbine cooling

NASA Technical Reports Server (NTRS)

Liebert, C. H.

1978-01-01

Spectral emittance measurements were made on a two-layer ceramic thermal barrier coating system consisting of a metal substrate, a NiCrAly bond coating and a yttria-stabilized zirconia ceramic coating. Spectral emittance data were obtained for the coating system at temperatures of 300 to 1590 K, ceramic thickness of zero to 0.076 centimeter, and wavelengths of 0.4 to 14.6 micrometers. The data were transformed into total hemispherical emittance values and correlated with respect to ceramic coating thickness and temperature using multiple regression curve fitting techniques. The results show that the ceramic thermal barrier coating system is highly reflective and significantly reduces radiation heat loads on cooled gas turbine engine components. Calculation of the radiant heat transfer within the nonisothermal, translucent ceramic coating material shows that the gas-side ceramic coating surface temperature can be used in heat transfer analysis of radiation heat loads on the coating system.

A quantitative AFM analysis of nano-scale surface roughness in various orthodontic brackets.

PubMed

Lee, Gi-Ja; Park, Ki-Ho; Park, Young-Guk; Park, Hun-Kuk

2010-10-01

In orthodontics, the surface roughnesses of orthodontic archwire and brackets affect the effectiveness of arch-guided tooth movement, corrosion behavior, and the aesthetics of orthodontic components. Atomic force microscopy (AFM) measurements were used to provide quantitative information on the surface roughness of the orthodontic material. In this study, the changes in surface roughness of various orthodontic bracket slots before and after sliding movement of archwire in vitro and in vivo were observed through the utilization of AFM. Firstly, we characterized the surface of four types of brackets slots as follows: conventional stainless steel (Succes), conventional ceramic (Perfect), self-ligating stainless steel (Damon) and self-ligating ceramic (Clippy-C) brackets. Succes) and Damon brackets showed relatively smooth surfaces, while Perfect had the roughest surface among the four types of brackets used. Secondly, after in vitro sliding test with beta titanium wire in two conventional brackets (Succes and Perfect), there were significant increases in only stainless steel bracket, Succes. Thirdly, after clinical orthodontic treatment for a maximum of 2 years, the self-ligating stainless steel bracket, Damon, showed a significant increase in surface roughness. But self-ligating ceramic brackets, Clippy-C, represented less significant changes in roughness parameters than self-ligating stainless steel ones. Based on the results of the AFM measurements, it is suggested that the self-ligating ceramic bracket has great possibility to exhibit less friction and better biocompatibility than the other tested brackets. This implies that these bracket slots will aid in the effectiveness of arch-guided tooth movement.

Numerical analysis of an entire ceramic kiln under actual operating conditions for the energy efficiency improvement.

PubMed

Milani, Massimo; Montorsi, Luca; Stefani, Matteo; Saponelli, Roberto; Lizzano, Maurizio

2017-12-01

The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption and the corresponding carbon dioxide emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. Numerical results are validated against experimental measurements carried out on a real ceramic kiln during regular production operations. The developed numerical model demonstrates to be an efficient tool for the investigation of different design solutions for the kiln's components. In addition, a number of control strategies for the system working conditions can be simulated and compared in order to define the best trade off in terms of fuel consumption and product quality. In particular, the paper analyzes the effect of a new burner type characterized by internal heat recovery capability aimed at improving the energy efficiency of the ceramic kiln. The fuel saving and the relating reduction of carbon dioxide emissions resulted in the order of 10% when compared to the standard burner. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and characterisation of novel low temperature ceramic and its implementation as substrate in dual segment CDRA

NASA Astrophysics Data System (ADS)

Kumari, Preeti; Tripathi, Pankaj; Sahu, Bhagirath; Singh, S. P.; Parkash, Om; Kumar, Devendra

2018-02-01

Li2O-(2-3x)MgO-(x)Al2O3-P2O5 (LMAP) (x = 0.00-0.08) ceramic system was prepared through solid state synthesis route at different sintering temperatures (800-925 °C). A small addition of Al2O3 (x = 0.02) in LMAP ceramics lowers the sintering temperature by more than 100 °C with good relative density of 94.13%. The sintered samples were characterized in terms of density, apparent porosity, water absorption, crystal structure, micro-structure and microwave dielectric properties. Silver compatibility test is also performed for its use as electrode material in low temperature co-fired ceramic (LTCC) application. To check the performance of the prepared LTCC as substrate, a microstrip-fed aperture-coupled dual segment cylindrical dielectric resonator antenna (DS-CDRA) is designed using LMAP (x = 0.02) ceramic as substrate material and Barium Strontium Titanate with 10 wt% of PbO-BaO-B2O3-SiO2 glass (BSTG) and Teflon as the components of resonating material. The simulation study of the DS-CDRA is performed using the Ansys High Frequency Structure Simulator (HFSS) software. A conductive coating of silver is used on the substrate. The simulated and measured -10 dB reflection coefficient bandwidths of 910 MHz (9.07-9.98 GHz at resonant frequency of 9.49 GHz) and 1080 MHz (8.68-9.76 GHz at resonant frequency of 9.36 GHz), respectively are achieved. The measured results of the fabricated antenna are found in good agreement with the simulation results. The prepared material can find potential applications in radar and radio navigation as well as radio astronomy and military satellite communication.

In vitro bioactivity behavior of modified multicomponent borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5

NASA Astrophysics Data System (ADS)

Marzouk, M. A.; ElBatal, F. H.; Ghoneim, N. A.

2018-02-01

Some multi-component borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5 were prepared. Multi-characterization techniques were carried out to investigate their bioactivity, corrosion weight loss after immersion in phosphate solution. Controlled thermal heat-treatment by two-step technique was done to convert the prepared glasses to their corresponding glass-ceramic derivatives. X-ray diffraction analysis was performed to identify the crystalline phases formed by thermal treatment. Infrared absorption of glasses and glass-ceramics reveal vibrational bands due to combined main triangular and tetrahedral borate groups in their specific wavenumbers besides some sharing of phosphate group. After immersion in the phosphate solution, two extra characteristic peaks are generated indicating the bioactivity of the studied glasses and glass-ceramics through the formation of calcium phosphate (hydroxyapatite). X-ray diffraction data indicate the formation of crystalline phases which are variable with the introduced dopants. The main crystalline phase identified is calcium borate together with some other phases some of which contain phosphate ions. These data indicate that the presence of CaO and P2O5 initiates phase separation and subsequent crystallization of the parent and doped glasses. Weight loss data indicate that glass-ceramics are obviously durable than the parent glasses. SEM micrographs of glass-ceramics before immersion show multiconstituent crystalline phases due to the basic chemical composition consisting of multicomponent mixed alkali and alkaline earth oxides beside P2O5 and with the main B2O3 constituent. After immersion, the crystalline phases are identified to be more distinct in different shapes because of the multi-composition involved.

Glass-ceramic joint and method of joining

DOEpatents

Meinhardt, Kerry D [Richland, WA; Vienna, John D [West Richland, WA; Armstrong, Timothy R [Clinton, TN; Pederson, Larry R [Kennewick, WA

2003-03-18

The present invention is a glass-ceramic material and method of making useful for joining a solid ceramic component and at least one other solid component. The material is a blend of M1-M2-M3, wherein M1 is BaO, SrO, CaO, MgO, or combinations thereof, M2 is Al.sub.2 O.sub.3, present in the blend in an amount from 2 to 15 mol %, M3 is SiO.sub.2 with up to 50 mol % B.sub.2 O.sub.3 that substantially matches a coefficient of thermal expansion of the solid electrolyte. According to the present invention, a series of glass ceramics in the M1-Al.sub.2 O.sub.3 -M3 system can be used to join or seal both tubular and planar solid oxide fuel cells, oxygen electrolyzers, and membrane reactors for the production of syngas, commodity chemicals and other products.

Incipient flocculation molding: A new ceramic-forming technique

NASA Astrophysics Data System (ADS)

Arrasmith, Steven Reade

Incipient Flocculation Molding (IFM) was conceived as a new near-net-shape forming technique for ceramic components. It was hypothesized that the development of a temperature-dependent deflocculant would result in a forming technique that is flexible, efficient, and capable of producing a superior microstructure with improved mechanical properties from highly reactive, submicron ceramic powders. IFM utilizes a concentrated, nonaqueous, sterically stabilized ceramic powder and/or colloidal suspension which is injected into a non-porous mold. The suspension is then flocculated by destabilizing the suspension by lowering the temperature. Flocculation is both rapid and reversible. Cooling to -20°C produces a green body with sufficient strength for removal from the mold. The solvent is removed from the green body by evaporation. The dried green body is subsequently sintered to form a dense ceramic monolith. This is the first ceramic forming method based upon the manipulation of a sterically-stabilized suspension. To demonstrate IFM, the process of grafting polyethylene glycol (PEG), with molecular weights from 600 to 8000, to alumina powders was investigated. The maximum grafted amounts were achieved by the technique of dispersing the alumina powders in molten polymer at 195°C. The ungrafted PEG was then removed by repeated centrifuging and redispersion in fresh distilled water. The rheological behavior of suspensions of the PEG-grafted powders in water, 2-propanol and 2-butanol were characterized. All of the aqueous suspensions were shear thinning. The PEG 4600-grafted alumina powder aqueous suspensions were the most fluid. Sample rods and bars were molded from 52 vol% PEG-grafted alumina suspensions in 2-butanol. The best results were obtained with a preheated aluminum mold lubricated with a fluorinated oil mold-release. The samples were dried, sintered, and their microstructure and density were compared with sintered samples dry pressed from the same alumina powder. Densities and microstructures were quite similar to those obtained by dry pressing and sintering these powders. Dried green samples with densities of ca. 57% of theoretical sintered to >96% of theoretical density. This research has demonstrated IFM as a viable ceramic forming process which has potential to be developed into an industrial process. Further research is needed to determine preferred molding parameters, other possible polymer-solvent systems, and investigate the use of other ceramic powders. The concepts developed for IFM may have potential applications in other ceramic forming processes, such as extrusion and rapid prototyping.

Luminescence properties of Eu3+-doped SiO2-LiYF4 glass-ceramic microrods

NASA Astrophysics Data System (ADS)

Secu, C. E.; Secu, M.

2015-09-01

Photoluminescence properties of the glass-ceramics microrods containing Eu3+-doped LiYF4 nanocrystals have been studied and characterized. Judd-Ofelt parameters and quantum efficiency has been computed from luminescence spectra and discussed by comparison to the glass ceramic bulk and pellet. The radiative decay rate Arad is higher in the glass ceramic rods (221 s-1) than in the glass ceramic bulk (130 s-1) but the quantum efficiency computed is very low (21%) compared to the glass-ceramic bulk (97%). There are effective non-radiative decay channels that might be related to an influence of the dimensional constraints imposed by the membrane pores during xerogel formation and subsequent glass ceramization.

Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

NASA Astrophysics Data System (ADS)

Ari-Wahjoedi, Bambang; Ginta, Turnad Lenggo; Parman, Setyamartana; Abustaman, Mohd Zikri Ahmad

2014-10-01

Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics is excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm-3 respectively, pore linear density of ±35 cm-1, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.

The precursors effects on biomimetic hydroxyapatite ceramic powders.

PubMed

Yoruç, Afife Binnaz Hazar; Aydınoğlu, Aysu

2017-06-01

In this study, effects of the starting material on chemical, physical, and biological properties of biomimetic hydroxyapatite ceramic powders (BHA) were investigated. Characterization and chemical analysis of BHA powders were performed by using XRD, FT-IR, and ICP-AES. Microstructural features such as size and morphology of the resulting BHA powders were characterized by using BET, nano particle sizer, pycnometer, and SEM. Additionally, biological properties of the BHA ceramic powders were also investigated by using water-soluble tetrazolium salts test (WST-1). According to the chemical analysis of BHA ceramic powders, chemical structures of ceramics which are prepared under different conditions and by using different starting materials show differences. Ceramic powders which are produced at 80°C are mainly composed of hydroxyapatite, dental hydroxyapatite (contain Na and Mg elements in addition to Ca), and calcium phosphate sulfide. However, these structures are altered at high temperatures such as 900°C depending on the features of starting materials and form various calcium phosphate ceramics and/or their mixtures such as Na-Mg-hydroxyapatite, hydroxyapatite, Mg-Whitlockit, and chloroapatite. In vitro cytotoxicity studies showed that amorphous ceramics produced at 80°C and ceramics containing chloroapatite structure as main or secondary phases were found to be extremely cytotoxic. Furthermore, cell culture studies showed that highly crystalline pure hydroxyapatite structures were extremely cytotoxic due to their high crystallinity values. Consequently, the current study indicates that the selection of starting materials which can be used in the production of calcium phosphate ceramics is very important. It is possible to produce calcium phosphate ceramics which have sufficient biocompatibility at physiological pH values and by using appropriate starting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Casting Of Multilayer Ceramic Tapes

NASA Technical Reports Server (NTRS)

Collins, Earl R., Jr.

1991-01-01

Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

Research & Development of Materials/Processing Methods for Continuous Fiber Ceramic Composites (CFCC) Phase 2 Final Report.

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

Szweda, A.

2001-01-01

The Department of Energy's Continuous Fiber Ceramic Composites (CFCC) Initiative that begun in 1992 has led the way for Industry, Academia, and Government to carry out a 10 year R&D plan to develop CFCCs for these industrial applications. In Phase II of this program, Dow Corning has led a team of OEM's, composite fabricators, and Government Laboratories to develop polymer derived CFCC materials and processes for selected industrial applications. During this phase, Dow Corning carried extensive process development and representative component demonstration activities on gas turbine components, chemical pump components and heat treatment furnace components.

Industrial waste utilization in the panels production for high buildings facade and socle facing

NASA Astrophysics Data System (ADS)

Vitkalova, Irina; Torlova, Anastasiya; Pikalov, Evgeniy; Selivanov, Oleg

2018-03-01

The research presents comprehensive utilization of such industrial waste as galvanic sludge, broken window glass as functional additives for producing ceramics for facade and socle paneling in high-rise construction. The basic charge component is low-plasticity clay, which does not allow producing high-quality products if used without any functional additives. The application of the mentioned above components broadens the resource base, reduces production cost and the mass of the products in comparison with the currently used facing ceramics. The decrease of product mass helps to reduce the load on the basement and to use ceramic material in high-rise construction more effectively. Additional advantage of the developed composition is the reducing of production energy intensity due to comparatively low pressing pressure and firing temperature thus reducing the overall production cost. The research demonstrates the experimental results of determining density, compressive strength, water absorption, porosity and frost resistance of the produced ceramic material. These characteristics prove that the material can be applied for high buildings outdoor paneling. Additional research results prove ecologic safety of the produced ceramic material.

Lightweight high performance ceramic material

DOEpatents

Nunn, Stephen D [Knoxville, TN

2008-09-02

A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

Lutetium oxide-based transparent ceramic scintillators

DOEpatents

Seeley, Zachary; Cherepy, Nerine; Kuntz, Joshua; Payne, Stephen A.

2016-01-19

In one embodiment, a transparent ceramic of sintered nanoparticles includes gadolinium lutetium oxide doped with europium having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YEu.sub.YO.sub.3, where X is any value within a range from about 0.05 to about 0.45 and Y is any value within a range from about 0.01 to about 0.2, and where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm. In another embodiment, a transparent ceramic scintillator of sintered nanoparticles, includes a body of sintered nanoparticles including gadolinium lutetium oxide doped with a rare earth activator (RE) having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YRE.sub.YO.sub.3, where RE is selected from the group consisting of: Sm, Eu, Tb, and Dy, where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm.

Collagen/hydroxyapatite composite materials with desired ceramic properties.

PubMed

Andronescu, Ecaterina; Voicu, Georgeta; Ficai, Maria; Mohora, Ioana Anita; Trusca, Roxana; Ficai, Anton

2011-01-01

Our purpose was to obtain and characterize some collagen/hydroxyapatite (COLL/HA) hybrid composite materials with desired ceramic properties. The ceramic properties of these materials were achieved by combining two drying methods: controlled air drying at 30°C followed by freeze-drying. Through the function of the air drying times, the materials morphology varies from porous materials (when the materials are freeze-dried) up to dense materials (when the materials are air-dried), while the combined drying allows us to obtain an intermediary morphology. The composite materials intended to be used as bone grafts and in a drug delivery system were characterized by XRD, FTIR, SEM, and also by determining the ceramic properties by using the Arthur method. The ceramic properties of these COLL/HA composite materials vary in large range, for instance the density of the materials varies from 0.06 up to 1.5 g/cm(3) while the porosity varies from 96.5% down to 27.5%.

Characterization of the bioactive and mechanical behavior of dental ceramic/sol-gel derived bioactive glass mixtures.

PubMed

Abbasi, Zahra; Bahrololoum, Mohammad E; Bagheri, Rafat; Shariat, Mohammad H

2016-02-01

Dental ceramics can be modified by bioactive glasses in order to develop apatite layer on their surface. One of the benefits of such modification is to prolong the lifetime of the fixed dental prosthesis by preventing the formation of secondary caries. Dental ceramic/sol-gel derived bioactive glass mixture is one of the options for this modification. In the current study, mixtures of dental ceramic/bioactive glass with different compositions were successfully produced. To evaluate their bioactive behavior, prepared samples were immersed in a simulated body fluid at various time intervals. The prepared and soaked specimens were characterized using Fourier transform infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. Since bioactive glasses have deleterious effects on the mechanical properties of dental ceramics, 3-point bending tests were used to evaluate the flexural strength, flexural strain, tangent modulus of elasticity and Weibull modulus of the specimens in order to find the optimal relationship between mechanical and bioactive properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fracture Toughness (KIC) of Lithography Based Manufactured Alumina Ceramic

NASA Astrophysics Data System (ADS)

Nindhia, T. G. T.; Schlacher, J.; Lube, T.

2018-04-01

Precision shaped ceramic components can be obtained by an emerging technique called Lithography based Ceramic Manufacturing (LCM). A green part is made from a slurry consisting of a ceramic powder in a photocurable binder with addition of dispersant and plasticizer. Components are built in a layer–by-layer way by exposing the desired cross- sections to light. The parts are subsequently sintered to their final density. It is a challenge to produce ceramic component with this method that yield the same mechanical properties in all direction. The fracture toughness (KIc) of of LCM-alumina (prepared at LITHOZ GmbH, Austria) was tested by using the Single-Edge-V-Notched Beam (SEVNB) method. Notches are made into prismatic bend-bars in all three direction X, Y and Z to recognize the value of fracture toughness of the material in all three directions. The microstructure was revealed with optical microscopy as well as Scanning Electron Microscopy (SEM). The results indicate that the fracture toughness in Y-direction has the highest value (3.10 MPam1/2) that is followed by the one in X-direction which is just a bit lower (2.90 MPam1/2). The Z-direction is found to have a similar fracture toughness (2.95 MPam1/2). This is supported by a homogeneous microstructure showing no hint of the layers used during production.

Alternating-Composition Layered Ceramic Barrier Coatings

NASA Technical Reports Server (NTRS)

Miller, Robert A.; Zhu, Dongming

2008-01-01

Ceramic thermal and environmental barrier coatings (T/EBCs) that contain multiple layers of alternating chemical composition have been developed as improved means of protecting underlying components of gas-turbine and other heat engines against both corrosive combustion gases and high temperatures.

Test Standard Developed for Determining the Slow Crack Growth of Advanced Ceramics at Ambient Temperature

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Salem, Jonathan A.

1998-01-01

The service life of structural ceramic components is often limited by the process of slow crack growth. Therefore, it is important to develop an appropriate testing methodology for accurately determining the slow crack growth design parameters necessary for component life prediction. In addition, an appropriate test methodology can be used to determine the influences of component processing variables and composition on the slow crack growth and strength behavior of newly developed materials, thus allowing the component process to be tailored and optimized to specific needs. At the NASA Lewis Research Center, work to develop a standard test method to determine the slow crack growth parameters of advanced ceramics was initiated by the authors in early 1994 in the C 28 (Advanced Ceramics) committee of the American Society for Testing and Materials (ASTM). After about 2 years of required balloting, the draft written by the authors was approved and established as a new ASTM test standard: ASTM C 1368-97, Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature. Briefly, the test method uses constant stress-rate testing to determine strengths as a function of stress rate at ambient temperature. Strengths are measured in a routine manner at four or more stress rates by applying constant displacement or loading rates. The slow crack growth parameters required for design are then estimated from a relationship between strength and stress rate. This new standard will be published in the Annual Book of ASTM Standards, Vol. 15.01, in 1998. Currently, a companion draft ASTM standard for determination of the slow crack growth parameters of advanced ceramics at elevated temperatures is being prepared by the authors and will be presented to the committee by the middle of 1998. Consequently, Lewis will maintain an active leadership role in advanced ceramics standardization within ASTM. In addition, the authors have been and are involved with several international standardization organizations including the Versailles Project on Advanced Materials and Standards (VAMAS), the International Energy Agency (IEA), and the International Organization for Standardization (ISO). The associated standardization activities involve fracture toughness, strength, elastic modulus, and the machining of advanced ceramics.

Refractory Oxidative-Resistant Ceramic Carbon Insulation

NASA Technical Reports Server (NTRS)

Leiser, Daniel B. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

2001-01-01

High-temperature, lightweight, ceramic carbon insulation is prepared by coating or impregnating a porous carbon substrate with a siloxane gel derived from the reaction of an organodialkoxy silane and an organotrialkoxy silane in an acid or base medium in the presence of the carbon substrate. The siloxane gel is subsequently dried on the carbon substrate to form a ceramic carbon precursor. The carbon precursor is pyrolyzed, in an inert atmosphere, to form the ceramic insulation containing carbon, silicon, and oxygen. The carbon insulation is characterized as a porous, fibrous, carbon ceramic tile which is particularly useful as lightweight tiles for spacecraft.

Fabrication and Testing of Ceramic Matrix Composite Propulsion Components

NASA Technical Reports Server (NTRS)

Effinger, Michael R.; Clinton, R. G., Jr.; Dennis, Jay; Elam, Sandy; Genge, Gary; Eckel, Andy; Jaskowiak, Martha H.; Kiser, J. Douglas; Lang, Jerry

2000-01-01

A viewgraph presentation outlines NASA's goals for the Second and Third Generation Reusable Launch Vehicles, placing emphasis on improving safety and decreasing the cost of transporting payloads to orbit. The use of ceramic matrix composite (CMC) technology is discussed. The development of CMC components, such as the Simplex CMC Blisk, cooled CMC nozzle ramps, cooled CMC thrust chambers, and CMC gas generators, are described, including challenges, test results, and likely future developments.

In-situ formation of multiphase electron beam physical vapor deposited barrier coatings for turbine components

DOEpatents

Subramanian, Ramesh

2001-01-01

A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base columnar thermal barrier coating (20) on the alloy surface, where a heat resistant ceramic oxide sheath material (32' or 34') covers the columns (28), and the sheath material is the reaction product of a precursor ceramic oxide sheath material and the base thermal barrier coating material.

Advanced Gas Turbine (AGT) power-train system development

NASA Technical Reports Server (NTRS)

Helms, H. E.; Johnson, R. A.; Gibson, R. K.

1982-01-01

Technical work on the design and component testing of a 74.5 kW (100 hp) advanced automotive gas turbine is described. Selected component ceramic component design, and procurement were tested. Compressor tests of a modified rotor showed high speed performance improvement over previous rotor designs; efficiency improved by 2.5%, corrected flow by 4.6%, and pressure ratio by 11.6% at 100% speed. The aerodynamic design is completed for both the gasifier and power turbines. Ceramic (silicon carbide) gasifier rotors were spin tested to failure. Improving strengths is indicated by burst speeds and the group of five rotors failed at speeds between 104% and 116% of engine rated speed. The emission results from combustor testing showed NOx levels to be nearly one order of magnitude lower than with previous designs. A one piece ceramic exhaust duct/regenerator seal platform is designed with acceptable low stress levels.

Lifetime Reliability Prediction of Ceramic Structures Under Transient Thermomechanical Loads

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Jadaan, Osama J.; Gyekenyesi, John P.

2005-01-01

An analytical methodology is developed to predict the probability of survival (reliability) of ceramic components subjected to harsh thermomechanical loads that can vary with time (transient reliability analysis). This capability enables more accurate prediction of ceramic component integrity against fracture in situations such as turbine startup and shutdown, operational vibrations, atmospheric reentry, or other rapid heating or cooling situations (thermal shock). The transient reliability analysis methodology developed herein incorporates the following features: fast-fracture transient analysis (reliability analysis without slow crack growth, SCG); transient analysis with SCG (reliability analysis with time-dependent damage due to SCG); a computationally efficient algorithm to compute the reliability for components subjected to repeated transient loading (block loading); cyclic fatigue modeling using a combined SCG and Walker fatigue law; proof testing for transient loads; and Weibull and fatigue parameters that are allowed to vary with temperature or time. Component-to-component variation in strength (stochastic strength response) is accounted for with the Weibull distribution, and either the principle of independent action or the Batdorf theory is used to predict the effect of multiaxial stresses on reliability. The reliability analysis can be performed either as a function of the component surface (for surface-distributed flaws) or component volume (for volume-distributed flaws). The transient reliability analysis capability has been added to the NASA CARES/ Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code. CARES/Life was also updated to interface with commercially available finite element analysis software, such as ANSYS, when used to model the effects of transient load histories. Examples are provided to demonstrate the features of the methodology as implemented in the CARES/Life program.

Fabrication and performance of porous lithium sodium potassium niobate ceramic

NASA Astrophysics Data System (ADS)

Chen, Caifeng; Zhu, Yuan; Ji, Jun; Cai, Feixiang; Zhang, Youming; Zhang, Ningyi; Wang, Andong

2018-02-01

Porous lithium sodium potassium niobate (LNK) ceramic has excellent piezoelectric properties, chemical stability and great chemical compatibility. It has a good application potential in the field of biological bone substitute. In the paper, porous LNK ceramic was fabricated with egg albumen foaming agent by foaming method. Effects of preparation process of the porous LNK ceramic on density, phase structure, hole size and piezoelectric properties were researched and characterized. The results show that the influence factors of LNK solid content and foaming agent addition are closely relevant to properties of the porous LNK ceramic. When solid content is 65% and foaming agent addition is 30%, the porous LNK ceramic has uniform holes and the best piezoelectric properties.

Health hazards of ceramic artists.

PubMed

Dorevitch, S; Babin, A

2001-01-01

Ceramic artists can be exposed to many hazards including metals (such as lead), fibrogenic dusts (such as silica), heat, repetitive motion, radiation, and toxic emissions from kilns. The health risks of these exposures have not been well characterized among artists, although limited information is available from commercial potteries. Adverse health effects may be prevented by using less hazardous materials (such as lead-free glazes), improved ventilation, and proper work practices. Special precautions must be in place if children have access to the ceramics studio. The use of glazed ceramic dishes can be a risk for lead toxicity. Food should not be stored in glazed ceramics, and pregnant women should avoid daily use of ceramic mugs for drinking hot beverages.

Characterizing ceramics and the interfacial adhesion to resin: I - The relationship of microstructure, composition, properties and fractography.

PubMed

Della Bona, Alvaro

2005-03-01

The appeal of ceramics as structural dental materials is based on their light weight, high hardness values, chemical inertness, and anticipated unique tribological characteristics. A major goal of current ceramic research and development is to produce tough, strong ceramics that can provide reliable performance in dental applications. Quantifying microstructural parameters is important to develop structure/property relationships. Quantitative microstructural analysis provides an association among the constitution, physical properties, and structural characteristics of materials. Structural reliability of dental ceramics is a major factor in the clinical success of ceramic restorations. Complex stress distributions are present in most practical conditions and strength data alone cannot be directly extrapolated to predict structural performance.

Cassettes for solid-oxide fuel cell stacks and methods of making the same

DOEpatents

Weil, K. Scott; Meinhardt, Kerry D; Sprenkle, Vincent L

2012-10-23

Solid-oxide fuel cell (SOFC) stack assembly designs are consistently investigated to develop an assembly that provides optimal performance, and durability, within desired cost parameters. A new design includes a repeat unit having a SOFC cassette and being characterized by a three-component construct. The three components include an oxidation-resistant, metal window frame hermetically joined to an electrolyte layer of a multi-layer, anode-supported ceramic cell and a pre-cassette including a separator plate having a plurality of vias that provide electrical contact between an anode-side collector within the pre-cassette and a cathode-side current collector of an adjacent cell. The third component is a cathode-side seal, which includes a standoff that supports a cathode channel spacing between each of the cassettes in a stack. Cassettes are formed by joining the pre-cassette and the window frame.

Synthesis of new 2-amino-4H-pyran-3,5-dicarboxylate derivatives using nanocrystalline MIIZr4(PO4)6 ceramics as reusable and robust catalysts under microwave irradiation

NASA Astrophysics Data System (ADS)

Safaei-Ghomi, Javad; Javidan, Abdollah; Ziarati, Abolfazl; Shahbazi-Alavi, Hossein

2015-08-01

In the present paper, we report the successful synthesis of nanocrystalline MIIZr4(PO4)6 ceramics (M: Mn, Ni, Fe, Co). These nano-structures were characterized by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer (VSM). Size of nano-structures was in the range of 20-150 nm. Nano-MIIZr4(PO4)6 as an efficient and green catalyst has been used for the preparation of 2-amino-4H-pyran-3,5-dicarboxylate derivatives by the three-component condensation reaction of ethyl cyanoacetate, ethyl acetoacetate, and various aromatic aldehydes under microwave irradiation. Extraordinarily, the best results were obtained using MnZr4(PO4)6 nanocrystallines as an efficient catalyst. This method provides several advantages including easy work-up, excellent yields, short reaction times, using of microwave as green method, recoverability of the catalyst, and little catalyst loading.

USV UHTC- Based Nose And WLE Experimental Test In SCIROCCO And CFD Rebuilding

NASA Astrophysics Data System (ADS)

Marino, G.; De Filippis, F.; Di Clement, M.; Russo, G.

2011-05-01

It is well known that sharp aerodynamic configurations could provide much more efficiency in “flying” during the re-entry phase of spacecrafts, and/or the hypersonic cruise of futuristic aerospace planes. However such innovation in the design criteria, implies a dramatic increase of the localized heat fluxes at the stagnation points of the leading edges of the aerodynamic surfaces that, as matter of fact, might then require dedicated thermal protection systems, able to sustain thermal loads much higher than those typically experienced by conventional materials applied on blunt bodies. In this perspective CIRA started its own investigations on the design methodology [1], characterization methods, manufacturing procedures, and qualification tests of medium size components based on exotic ceramic materials able to sustain temperatures even exceeding 2000°C, the so called Ultra High Temperature Ceramics (UHTC’s). This paper summarizes CIRA experience achieved so far trough the test opportunities conducted on-ground in the SCIROCCO plasma wind tunnel.

Wettability and surface free energy of polarised ceramic biomaterials.

PubMed

Nakamura, Miho; Hori, Naoko; Namba, Saki; Toyama, Takeshi; Nishimiya, Nobuyuki; Yamashita, Kimihiro

2015-01-13

The surface modification of ceramic biomaterials used for medical devices is expected to improve osteoconductivity through control of the interfaces between the materials and living tissues. Polarisation treatment induced surface charges on hydroxyapatite, β-tricalcium phosphate, carbonate-substituted hydroxyapatite and yttria-stabilized zirconia regardless of the differences in the carrier ions participating in the polarisation. Characterization of the surfaces revealed that the wettability of the polarised ceramic biomaterials was improved through the increase in the surface free energies compared with conventional ceramic surfaces.

Advanced ceramic matrix composite materials for current and future propulsion technology applications

NASA Astrophysics Data System (ADS)

Schmidt, S.; Beyer, S.; Knabe, H.; Immich, H.; Meistring, R.; Gessler, A.

2004-08-01

Current rocket engines, due to their method of construction, the materials used and the extreme loads to which they are subjected, feature a limited number of load cycles. Various technology programmes in Europe are concerned, besides developing reliable and rugged, low cost, throwaway equipment, with preparing for future reusable propulsion technologies. One of the key roles for realizing reusable engine components is the use of modern and innovative materials. One of the key technologies which concern various engine manufacturers worldwide is the development of fibre-reinforced ceramics—ceramic matrix composites. The advantages for the developers are obvious—the low specific weight, the high specific strength over a large temperature range, and their great damage tolerance compared to monolithic ceramics make this material class extremely interesting as a construction material. Over the past years, the Astrium company (formerly DASA) has, together with various partners, worked intensively on developing components for hypersonic engines and liquid rocket propulsion systems. In the year 2000, various hot-firing tests with subscale (scale 1:5) and full-scale nozzle extensions were conducted. In this year, a further decisive milestone was achieved in the sector of small thrusters, and long-term tests served to demonstrate the extraordinary stability of the C/SiC material. Besides developing and testing radiation-cooled nozzle components and small-thruster combustion chambers, Astrium worked on the preliminary development of actively cooled structures for future reusable propulsion systems. In order to get one step nearer to this objective, the development of a new fibre composite was commenced within the framework of a regionally sponsored programme. The objective here is to create multidirectional (3D) textile structures combined with a cost-effective infiltration process. Besides material and process development, the project also encompasses the development of special metal/ceramic and ceramic/ceramic joining techniques as well as studying and verifying non destructive investigation processes for the purpose of testing components.

CaO-Al2O3 glass-ceramic as a joining material for SiC based components: A microstructural study of the effect of Si-ion irradiation

NASA Astrophysics Data System (ADS)

Casalegno, Valentina; Kondo, Sosuke; Hinoki, Tatsuya; Salvo, Milena; Czyrska-Filemonowicz, Aleksandra; Moskalewicz, Tomasz; Katoh, Yutai; Ferraris, Monica

2018-04-01

The aim of this work was to investigate and discuss the microstructure and interface reaction of a calcia-alumina based glass-ceramic (CA) with SiC. CA has been used for several years as a glass-ceramic for pressure-less joining of SiC based components. In the present work, the crystalline phases in the CA glass-ceramic and at the CA/SiC interface were investigated and the absence of any detectable amorphous phase was assessed. In order to provide a better understanding of the effect of irradiation on the joining material and on the joints, Si ion irradiation was performed both on bulk CA and CA joined SiC. CA glass-ceramic and CA joined SiC were both irradiated with 5.1 MeV Si2+ ions to 3.3 × 1020 ions/m2 at temperatures of 400 and 800 °C at DuET facility, Kyoto University. This corresponds to a damage level of 5 dpa for SiC averaged over the damage range. This paper presents the results of a microstructural analysis of the irradiated samples as well as an evaluation of the dimensional stability of the CA glass-ceramic and its irradiation temperature and/or damage dependence.

Characterizing ceramics and the interfacial adhesion to resin: II- the relationship of surface treatment, bond strength, interfacial toughness and fractography.

PubMed

Della-Bona, Alvaro

2005-06-01

The clinical success of resin bonding procedures for indirect ceramic restorations and ceramic repairs depends on the quality and durability of the bond between the ceramic and the resin. The quality of this bond will depend upon the bonding mechanisms that are controlled in part by the surface treatment that promote micromechanical and/or chemical bonding to the substrate. The objective of this review is to correlate interfacial toughness (K A) with fracture surface morphological parameters of the dental ceramic-resin systems as a function of ceramic surface treatment. This analysis is designed to identify mechanisms that promote adhesion of these ceramic-resin systems and an appropriate bond test method to yield relevant adhesion performance data.

Hall Thruster Thermal Modeling and Test Data Correlation

NASA Technical Reports Server (NTRS)

Myers, James

2016-01-01

HERMeS - Hall Effect Rocket with Magnetic Shielding. Developed through a joint effort by NASA/GRC and the Jet Propulsion Laboratory (JPL). Design goals: High power (12.5 kW) high Isp (3000 sec), high efficiency (> 60%), high throughput (10,000 kg), reduced plasma erosion and increased life (5 yrs) to support Asteroid Redirect Robotic Mission (ARRM). Further details see "Performance, Facility Pressure Effects and Stability Characterization Tests of NASAs HERMeS Thruster" by H. Kamhawi and team. Hall Thrusters (HT) inherently operate at elevated temperatures approx. 600 C (or more). Due to electric magnetic (E x B) fields used to ionize and accelerate propellant gas particles (i.e., plasma). Cooling is largely limited to radiation in vacuum environment.Thus the hardware components must withstand large start-up delta-T's. HT's are constructed of multiple materials; assorted metals, non-metals and ceramics for their required electrical and magnetic properties. To mitigate thermal stresses HT design must accommodate the differential thermal growth from a wide range of material Coef. of Thermal Expansion (CTEs). Prohibiting the use of some bolted/torqued interfaces.Commonly use spring loaded interfaces, particularly at the metal-to-ceramic interfaces to allow for slippage.However most component interfaces must also effectively conduct heat to the external surfaces for dissipation by radiation.Thus contact pressure and area are important.

The impact of microwave stray radiation to in-vessel diagnostic components

NASA Astrophysics Data System (ADS)

Hirsch, M.; Laqua, H. P.; Hathiramani, D.; Oosterbeek, J.; Baldzuhn, J.; Biedermann, C.; v d Brand, H.; Cardella, A.; Erckmann, V.; Jimenez, R.; König, R.; Köppen, M.; Parquay, S.; Zhang, D.; W7-X Team

2014-08-01

Microwave stray radiation resulting from unabsorbed multiple reflected ECRH / ECCD beams may cause severe heating of microwave absorbing in-vessel components such as gaskets, bellows, windows, ceramics and cable insulations. In view of long-pulse operation of WENDELSTEIN-7X the MIcrowave STray RAdiation Launch facility, MISTRAL, allows to test in-vessel components in the environment of isotropic 140 GHz microwave radiation at power load of up to 50 kW/m2 over 30 min. The results show that both, sufficient microwave shielding measures and cooling of all components are mandatory. If shielding/cooling measures of in-vessel diagnostic components are not efficient enough, the level of stray radiation may be (locally) reduced by dedicated absorbing ceramic coatings on cooled structures.

Status of the Ford program to evaluate ceramics for stator applications in automotive gas turbine engines

NASA Technical Reports Server (NTRS)

Trela, W.

1980-01-01

The paper reviews the progress of the major technical tasks of the DOE/NASA/Ford program Evaluation of Ceramics for Stator Applications in Automotive Gas Turbine Engines: reliability prediction, stator fabrication, material characterization, and stator evaluation. A fast fracture reliability model was prepared for a one-piece ceramic stator. Periodic inspection results are presented.

Terahertz characterization of Y2O3-added AlN ceramics

NASA Astrophysics Data System (ADS)

Kang, Seung Beom; Chung, Dong Chul; Kim, Sung-Jin; Chung, Jun-Ki; Park, Sang-Yeup; Kim, Ki-Chul; Kwak, Min Hwan

2016-12-01

Terahertz optical and dielectric properties of AlN ceramics fabricated by hot pressed sintering are investigated by THz time-domain spectroscopy in the frequency range of 0.2-3.5 THz. The measured properties of the pure AlN ceramic are compared with those of Y2O3-added AlN ceramic. Two prominent resonance modes, which are essentially responsible for the dielectric properties of the Y2O3-added AlN in terahertz regime, are characterized at ωTO1/(2π) = 2.76 THz (92 cm-1) and ωTO2/(2π) = 18.2 THz (605 cm-1) and are well described by the pseudo-harmonic oscillator model through theoretical fitting. The resonance ωTO1 at 2.76 THz is proposed to be due to the formation of a YAG (Y3Al5O12) secondary phase in Y2O3-added AlN ceramic. From the experimental results, good correlation is observed between the prominent peak of YAG secondary phase at 2.76 THz and thermal conductivity. Additionally, there is a high correlation between densification and refractive index of AlN ceramics fabricated by hot pressed sintering.

Affordable, Robust Ceramic Joining Technology (ARCJoinT) Given 1999 R and D 100 Award

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay

2000-01-01

Advanced ceramics and fiber-reinforced ceramic matrix composites with high strength and toughness, good thermal conductivity, thermal shock resistance, and oxidation resistance are needed for high-temperature structural applications in advanced high-efficiency and high-performance engines, space propulsion components, and land-based systems. The engineering designs of these systems require the manufacturing of large parts with complex shapes, which are either quite expensive or impossible to fabricate. In many instances, it is more economical to build complex shapes by joining together simple geometrical shapes. Thus, joining has been recognized as an enabling technology for the successful utilization of advanced ceramics and fiber-reinforced composite components in high-temperature applications. However, such joints must retain their structural integrity at high temperatures and must have mechanical strength and environmental stability comparable to those of the bulk materials. In addition, the joining technique should be robust, practical, and reliable. ARCJoinT, which is based on the reaction-forming approach, is unique in terms of producing joints with tailorable microstructures. The formation of joints by this approach is attractive since the thermomechanical properties of the joint interlayer can be tailored to be very close to those of the base materials. In addition, high-temperature fixturing is not needed to hold the parts at the infiltration temperature. The joining process begins with the application of a carbonaceous mixture in the joint area, holding the items to be joined in a fixture, and curing at 110 to 120 C for 10 to 20 min. This step fastens the pieces together. Then, silicon or a silicon alloy in tape, paste, or slurry form is applied around the joint region and heated to 1250 to 1425 C (depending on the type of infiltrant) for 10 to 15 min. The molten silicon or silicon-refractory metal alloy reacts with carbon to form silicon carbide with controllable amounts of silicon and other phases as determined by the alloy composition. Joint thickness can be readily controlled through adjustments of the properties of the carbonaceous paste and the applied fixturing force. The photograph shows various shapes of silicon-carbide-based ceramics and fiberreinforced composites that have been joined using ARCJoinT. Thermomechanical and thermochemical characterization of joints is underway for a wide variety of silicon-carbidebased advanced ceramics and fiber-reinforced composites under the hostile environments that will be encountered in engine applications. ARCJoinT, which was developed by researchers at the NASA Glenn Research Center at Lewis Field, received R&D Magazine's prestigious R&D 100 Award in 1999.

Corrosion resistant ceramic materials

DOEpatents

Kaun, Thomas D.

1995-01-01

Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

Corrosion resistant ceramic materials

DOEpatents

Kaun, Thomas D.

1996-01-01

Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

Corrosion resistant ceramic materials

DOEpatents

Kaun, T.D.

1996-07-23

Ceramic materials are disclosed which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200--550 C or organic salt (including SO{sub 2} and SO{sub 2}Cl{sub 2}) at temperatures of 25--200 C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components. 1 fig.

Infrared Imaging of Carbon and Ceramic Composites: Data Reproducibility

NASA Astrophysics Data System (ADS)

Knight, B.; Howard, D. R.; Ringermacher, H. I.; Hudson, L. D.

2010-02-01

Infrared NDE techniques have proven to be superior for imaging of flaws in ceramic matrix composites (CMC) and carbon silicon carbide composites (C/SiC). Not only can one obtain accurate depth gauging of flaws such as delaminations and layered porosity in complex-shaped components such as airfoils and other aeronautical components, but also excellent reproducibility of image data is obtainable using the STTOF (Synthetic Thermal Time-of-Flight) methodology. The imaging of large complex shapes is fast and reliable. This methodology as applied to large C/SiC flight components at the NASA Dryden Flight Research Center will be described.

Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

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

Ari-Wahjoedi, Bambang, E-mail: bambang-ariwahjoedi@petronas.com.my; Centre for Intelligent Signal and Imaging Research, Universiti Teknologi PETRONAS, Bandar Seri Iskandar; Ginta, Turnad Lenggo

2014-10-24

Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics ismore » excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm{sup −3} respectively, pore linear density of ±35 cm{sup −1}, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.« less

Light-weight ceramic insulation

NASA Technical Reports Server (NTRS)

Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

2002-01-01

Ultra-high temperature, light-weight, ceramic insulation such as ceramic tile is obtained by pyrolyzing a siloxane gel derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes may contain also an effective amount of a mono- or trialkoxy silane to obtain the siloxane gel. The siloxane gel is dried at ambient pressures to form a siloxane ceramic precursor without significant shrinkage. The siloxane ceramic precursor is subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation, can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C. and is particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

Materials technology assessment for stirling engines

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Witzke, W. R.; Watson, G. K.; Johnston, J. R.; Croft, W. J.

1977-01-01

A materials technology assessment of high temperature components in the improved (metal) and advanced (ceramic) Stirling engines was undertaken to evaluate the current state-of-the-art of metals and ceramics, identify materials research and development required to support the development of automotive Stirling engines, and to recommend materials technology programs to assure material readiness concurrent with engine system development programs. The most critical component for each engine is identified and some of the material problem areas are discussed.

Safe Life Propulsion Design Technologies (3rd Generation Propulsion Research and Technology)

NASA Technical Reports Server (NTRS)

Ellis, Rod

2000-01-01

The tasks outlined in this viewgraph presentation on safe life propulsion design technologies (third generation propulsion research and technology) include the following: (1) Ceramic matrix composite (CMC) life prediction methods; (2) Life prediction methods for ultra high temperature polymer matrix composites for reusable launch vehicle (RLV) airframe and engine application; (3) Enabling design and life prediction technology for cost effective large-scale utilization of MMCs and innovative metallic material concepts; (4) Probabilistic analysis methods for brittle materials and structures; (5) Damage assessment in CMC propulsion components using nondestructive characterization techniques; and (6) High temperature structural seals for RLV applications.

Thermal and mechanical analysis of major components for the advanced adiabatic diesel engine

NASA Technical Reports Server (NTRS)

1983-01-01

The proposed design for the light duty diesel is an in-line four cylinder spark assisted diesel engine mounted transversely in the front of the vehicle. The engine has a one piece cylinder head, with one intake valve and one exhaust valve per cylinder. A flat topped piston is used with a cylindrical combustion chamber recessed into the cylinder head directly under the exhaust valve. A single ceramic insert is cast into the cylinder head to insulate both the combustion chamber and the exhaust port. A similar ceramic insert is cast into the head to insulate the intake port. A ceramic faceplate is pressed into the combustion face of the head to insulate the face of the head from hot combustion gas. The valve seats are machined directly into the ceramic faceplate for the intake valve and into the ceramic exhaust pot insert for the exhaust valve. Additional ceramic applications in the head are the use of ceramic valve guides and ceramic insulated valves. The ceramic valve guides are press fit into the head and are used for increased wear resistance. The ceramic insulated valves are conventional valves with the valve faces plasma spray coated with ceramic for insulation.

Mechanical and thermal characterization of a ceramic/glass composite seal for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Dev, Bodhayan; Walter, Mark E.; Arkenberg, Gene B.; Swartz, Scott L.

2014-01-01

Solid oxide fuel cells (SOFCs) require seals that can function in harsh, elevated temperature environments. Comprehensive characterization and understanding of seals is needed for commercially viable SOFCs. The present research focuses on a novel ceramic/glass composite seal that is produced by roller compaction or tape casting of glass and ceramic powders and an organic binder. Upon heat treatment, micro-voids and surface anomalies are formed. Increased heating and cooling rates during the heat treatment resulted in more and larger voids. The first goal of the current research is to suggest an appropriate heating and cooling rate to minimize the formation of microstructural defects. After identifying an appropriate cure cycle, seals were thermally cycled and then characterized with laser dilatometry, X-ray diffraction, and sonic resonance. From these experiments the crystalline phases, thermal expansion, and elastic properties were determined. Subsequently compression testing with an acoustic emission (AE) sensor and post-test microstructural analysis were used to identify the formation of damage. By fully understanding the characteristics of this ceramic/glass composite seal, next generation seals can be fabricated for improved performance.

Electrical conductivity and Hf 4+ ion substitution range in NaSICON system

NASA Astrophysics Data System (ADS)

Essoumhi, A.; Favotto, C.; Mansori, M.; Ouzaouit, K.; Satre, P.

2007-03-01

In this paper, we present the synthesis and characterizations of NaSICON-type ionic conducting ceramics of the general formula Na 1+ xM 1.775Si x-0.9P 3.9- xO 12 with 1.8 ≤ x ≤ 2.2 and M = Zr or Hf. The effect of the total substitution of zirconium by hafnium on electric properties has been studied. The various compositions were prepared by using the sol-gel method and the synthesized precursors were characterized by coupled DTA-TG. The oxides obtained after pyrolysis of the precursors were identified by X-ray diffraction. A sintering study by thermodilatometry permits to select the best thermal cycle adapted to our ceramics. Furthermore, the electric conductivity of the sintered ceramic samples was characterized by complex impedance spectroscopy. These results show that ceramics containing Zr synthesized by soft method, present a higher total conductivity than those obtained in literature (to be around 10 -4 S cm -1). The total substitution of Zr by Hf still improves this conductivity for some compositions.

Ballistic Performance of Porous Ceramic Thermal Protection Systems at 9 km/s

NASA Technical Reports Server (NTRS)

Miller, Joshua E.; Bohl, W. E.; Foreman, C. D.; Christiansen, Eric L.; Davis, B. A.

2009-01-01

Porous-ceramic, thermal-protection-systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of manned spacecraft, Orion. These materials insulate the structural components and sensitive electronic components of a spacecraft against the intense thermal environments of atmospheric reentry. Furthermore, these materials are also highly exposed to space environmental hazards like meteoroid and orbital debris impacts. This paper discusses recent impact testing up to 9 km/s on ceramic tiles similar to those used on the Orbiter. These tiles have a porous-batting of nominally 8 lb/cubic ft alumina-fiber-enhanced-thermal-barrier (AETB8) insulating material coated with a damage-resistant, toughened-unipiece-fibrous-insulation (TUFI) layer.

Ceramic component reliability with the restructured NASA/CARES computer program

NASA Technical Reports Server (NTRS)

Powers, Lynn M.; Starlinger, Alois; Gyekenyesi, John P.

1992-01-01

The Ceramics Analysis and Reliability Evaluation of Structures (CARES) integrated design program on statistical fast fracture reliability and monolithic ceramic components is enhanced to include the use of a neutral data base, two-dimensional modeling, and variable problem size. The data base allows for the efficient transfer of element stresses, temperatures, and volumes/areas from the finite element output to the reliability analysis program. Elements are divided to insure a direct correspondence between the subelements and the Gaussian integration points. Two-dimensional modeling is accomplished by assessing the volume flaw reliability with shell elements. To demonstrate the improvements in the algorithm, example problems are selected from a round-robin conducted by WELFEP (WEakest Link failure probability prediction by Finite Element Postprocessors).

Ceramic Cerami Turbine Nozzle

DOEpatents

Boyd, Gary L.

1997-04-01

A turbine nozzle vane assembly having a preestablished rate of thermal expansion is positioned in a gas turbine engine and being attached to conventional metallic components. The metallic components having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine nozzle vane assembly. The turbine nozzle vane assembly includes an outer shroud and an inner shroud having a plurality of horizontally segmented vanes therebetween being positioned by a connecting member positioning segmented vanes in functional relationship one to another. The turbine nozzle vane assembly provides an economical, reliable and effective ceramic component having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the other component.

Characterization and inventory of PCDD/F emissions from the ceramic industry in China.

PubMed

Lu, Mang; Wang, Guoxiang; Zhang, Zhongzhi; Su, Youming

2012-04-03

The ceramic industry is considered to be a potential source of dioxins (polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), considering the widespread distribution of dioxins in kaolinitic clays. Nevertheless, studies on the emission of dioxins from the ceramic industry are still very scarce. In this study, raw clays and stack gases from six typical ceramic plants in China were collected and analyzed to estimate the emission of dioxins from the ceramic industry. Dioxin profiles in raw clays were characterized by the domination of the congener octachlorodibenzo-p-dioxin (OCDD), and the contents of other congeners declined with the decreasing degree of chlorination. During the ceramic firing process, a considerable amount (16.5-25.1 wt % of the initial quantity in raw clays) of the dioxins was not destroyed and was released to the atmosphere. Dechlorination of OCDD generated a broad distribution within the PCDD congeners including a variety of non-2,3,7,8-substituted ones with the mass abundance of 0.4-3.6%. Based on the mean concentrations measured in this study, the inventory of PCDD/Fs from the manufacturing of ceramics on the Chinese scale was estimated to be 7.94 kg/year; the corresponding value on the I-TEQ basis is 133.6 g I-TEQ/year. This accounts for about 1.34% (I-TEQ basis) of the total emission of dioxins to the environment in China. The results suggest that the ceramic industry is a significant source of dioxins in the environment.

Film Cooled Recession of SiC/SiC Ceramic Matrix Composites: Test Development, CFD Modeling and Experimental Observations

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Sakowski, Barbara A.; Fisher, Caleb

2014-01-01

SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. However, the environmental stability of Si-based ceramics in high pressure, high velocity turbine engine combustion environment is of major concern. The water vapor containing combustion gas leads to accelerated oxidation and corrosion of the SiC based ceramics due to the water vapor reactions with silica (SiO2) scales forming non-protective volatile hydroxide species, resulting in recession of the ceramic components. Although environmental barrier coatings are being developed to help protect the CMC components, there is a need to better understand the fundamental recession behavior of in more realistic cooled engine component environments.In this paper, we describe a comprehensive film cooled high pressure burner rig based testing approach, by using standardized film cooled SiCSiC disc test specimen configurations. The SiCSiC specimens were designed for implementing the burner rig testing in turbine engine relevant combustion environments, obtaining generic film cooled recession rate data under the combustion water vapor conditions, and helping developing the Computational Fluid Dynamics (CFD) film cooled models and performing model validation. Factors affecting the film cooled recession such as temperature, water vapor concentration, combustion gas velocity, and pressure are particularly investigated and modeled, and compared with impingement cooling only recession data in similar combustion flow environments. The experimental and modeling work will help predict the SiCSiC CMC recession behavior, and developing durable CMC systems in complex turbine engine operating conditions.

Perovskite electrodes and method of making the same

DOEpatents

Seabaugh, Matthew M [Columbus, OH; Swartz, Scott L [Columbus, OH

2009-09-22

The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

Perovskite electrodes and method of making the same

DOEpatents

Seabaugh, Matthew M.; Swartz, Scott L.

2005-09-20

The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

Lava ultimate resin nano ceramic for CAD/ CAM: customization case study.

PubMed

Koller, M; Arnetzl, G V; Holly, L; Arnetzl, G

2012-01-01

Lava Ultimate Resin Nano Ceramic (RNC) blocks are innovative new CAD/CAM materials that make it possible to achieve superior esthetic results in easy steps. The blocks are made of nano ceramic particles embedded in a highly cured resin matrix. Therefore, composite materials can be used to characterize and adjust resin nano ceramic restorations after milling. The milled RNC restorations can be individualized intra-orally or extra-orally, either before or after insertion. Unlike conventional ceramic restorations, customization and glaze firing is neither necessary nor possible with RNC restorations. This opens up the opportunity for intraoral individualization and adaptation of the restorations.

Trends of microwave dielectric materials for antenna application

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

Sulong, T. A. T., E-mail: tuanamirahtuansulong@gmail.com; Osman, R. A. M., E-mail: rozana@unimap.edu.my; Idris, M. S., E-mail: sobri@unimap.edu.my

Rapid development of a modern microwave communication system requires a high quality microwave dielectric ceramic material to be used as mobile and satellite communication. High permittivity of dielectric ceramics leads to fabrication of compact device for electronic components. Dielectric ceramics which used for microwave applications required three important parameters such as high or appropriate permittivity (ε{sub r}), high quality factor (Q {sub f} ≥ 5000 GH z) and good temperature coefficient of resonant frequency (τ{sub f}). This paper review of various dielectric ceramic materials used as microwave dielectric materials and related parameters for antenna applications.

Volume II: Compendium Abstracts

DTIC Science & Technology

2008-08-01

project developed a fast and simple method of characterization for ceramic , polymer composite, and ceramic -composite materials systems. Current methods...incrementally at 1-inch intervals and displayed as a false-color image map of the sample. This experimental setup can be easily scaled from single ceramic ...low-power, high-force characteristics of lead zirconate titanate ( PZT ) and an offset-beam design to achieve rotational or near-linear translational

Refractory ceramic compositions and method for preparing same

DOEpatents

Holcombe, Jr., Cressie E.; Morrow, Margaret K.

1976-07-13

This invention relates to ceramic compositions of tungsten and tantalum oxides including 0 to 33 1/3 mole percent of a metal oxide such as hafnia. These ceramics are characterized by melting points greater than about 1400.degree.C and selectively controlled coefficients of thermal expansion of essentially zero to a negative value in the temperature range of 20.degree. to 1000.degree.C.

Metals and Ceramics Division Materials Sciences Program. Annual progress report for period ending December 31, 1985

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

Stiegler, J.O.

1986-06-01

The report is divided into the following: structural characterization, high-temperature alloy research, structural ceramics, radiation effects, structure and properties of surfaces and interfaces, and collaborative research centers. (DLC)

Bluish-green color emitting Ba2Si3O8:Eu2+ ceramic phosphors for white light-emitting diodes.

PubMed

Xiao, F; Xue, Y N; Zhang, Q Y

2009-10-15

This paper reports on the structural and optical properties of Eu(2+) activated Ba(2)Si(3)O(8) ceramic phosphors synthesized by a sol-gel method. The ceramic phosphors have been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and fluorescence measurements. The structural characterization results suggest that the as-prepared phosphors are of single phase monoclinic Ba(2)Si(3)O(8) with rod-like morphology. A broad excitation band ranging from 300 to 410 nm matches well with the ultraviolet (UV) radiation of light-emitting diodes (LEDs). Upon 380 nm UV light excitation, these phosphors emit bluish-green emission centered at 500 nm with color coordination (x=0.25, y=0.40). All the obtained results indicate that the Ba(2)Si(3)O(8):Eu(2+) ceramic phosphors are promising bluish-green candidates for the phosphor-converted white LEDs.

The ceramics of Malpaís of Zacapu, Michoacán, Mexico, during the Early and Middle Postclassic periods (900-1450 AD): Micro-chemical characterization of surface paintings

NASA Astrophysics Data System (ADS)

Jadot, E.; Schiavon, N.; Manso, M.

2016-05-01

Tarascan ceramic sherds from two Postclassical archaeological sites (900-1450 AD) at the Malpaís of Zacapu, Michoacán, Mexico, were investigated by combining Back-Scattered Scanning Electron Microscopy and Energy Dispersive Spectroscopy (BSEM-EDS), μ-X-Ray Diffractometry (μ-XRD), μ-X-ray Fluorescence Spectroscopy (μ-XRF) and μ-Raman Spectroscopy. These sherds are famous for their forms and decorations although the composition of its raw materials remains so far unknown and focused only on the composition of the ceramic paste. For the purpose of surface decoration characterization, the pigments used in slips and paintings were identified as hematite, magnetite, amorphous carbon, graphite and lignite. Furthermore chemical and molecular structure determination allowed the identification of technological aspects such as the firing temperatures and atmospheres used in ceramics production.

[Ceramic-on-ceramic bearings in total hip arthroplasty (THA)].

PubMed

Sentürk, U; Perka, C

2015-04-01

The main reason for total hip arthroplasty (THA) revision is the wear-related aseptic loosening. Younger and active patients after total joint replacement create high demands, in particular, on the bearings. The progress, especially for alumina ceramic-on-ceramic bearings and mixed ceramics have solved many problems of the past and lead to good in vitro results. Modern ceramics (alumina or mixed ceramics containing alumina) are extremely hard, scratch-resistant, biocompatible, offer a low coefficient of friction, superior lubrication and have the lowest wear rates in comparison to all other bearings in THA. The disadvantage of ceramic is the risk of material failure, i.e., of ceramic fracture. The new generation of mixed ceramics (delta ceramic), has reduced the risk of head fractures to 0.03-0.05 %, but the risk for liner fractures remains unchanged at about 0.02 %. Assuming a non-impinging component implantation, ceramic-on-ceramic bearings have substantial advantages over all other bearings in THA. Due to the superior hardness, ceramic bearings produce less third body wear and are virtually impervious to damage from instruments during the implantation process. A specific complication for ceramic-on-ceramic bearings is "squeaking". The high rate of reported squeaking (0.45 to 10.7 %) highlights the importance of precise implant positioning and the stem and patient selection. With precise implant positioning this problem is rare with many implant designs and without clinical relevance. The improved tribology and the presumable resulting implant longevity make ceramic-on-ceramic the bearing of choice for young and active patients. Georg Thieme Verlag KG Stuttgart · New York.

High-temperature behavior of advanced spacecraft TPS

NASA Technical Reports Server (NTRS)

Pallix, Joan

1994-01-01

The objective of this work has been to develop more efficient, lighter weight, and higher temperature thermal protection systems (TPS) for future reentry space vehicles. The research carried out during this funding period involved the design, analysis, testing, fabrication, and characterization of thermal protection materials to be used on future hypersonic vehicles. This work is important for the prediction of material performance at high temperature and aids in the design of thermal protection systems for a number of programs including programs such as the National Aerospace Plane (NASP), Pegasus and Pegasus/SWERVE, the Comet Rendezvous and Flyby Vehicle (CRAF), and the Mars mission entry vehicles. Research has been performed in two main areas including development and testing of thermal protection systems (TPS) and computational research. A variety of TPS materials and coatings have been developed during this funding period. Ceramic coatings were developed for flexible insulations as well as for low density ceramic insulators. Chemical vapor deposition processes were established for the fabrication of ceramic matrix composites. Experimental testing and characterization of these materials has been carried out in the NASA Ames Research Center Thermophysics Facilities and in the Ames time-of-flight mass spectrometer facility. By means of computation, we have been better able to understand the flow structure and properties of the TPS components and to estimate the aerothermal heating, stress, ablation rate, thermal response, and shape change on the surfaces of TPS. In addition, work for the computational surface thermochemistry project has included modification of existing computer codes and creating new codes to model material response and shape change on atmospheric entry vehicles in a variety of environments (e.g., earth and Mars atmospheres).

High-temperature behavior of advanced spacecraft TPS

NASA Astrophysics Data System (ADS)

Pallix, Joan

1994-05-01

The objective of this work has been to develop more efficient, lighter weight, and higher temperature thermal protection systems (TPS) for future reentry space vehicles. The research carried out during this funding period involved the design, analysis, testing, fabrication, and characterization of thermal protection materials to be used on future hypersonic vehicles. This work is important for the prediction of material performance at high temperature and aids in the design of thermal protection systems for a number of programs including programs such as the National Aerospace Plane (NASP), Pegasus and Pegasus/SWERVE, the Comet Rendezvous and Flyby Vehicle (CRAF), and the Mars mission entry vehicles. Research has been performed in two main areas including development and testing of thermal protection systems (TPS) and computational research. A variety of TPS materials and coatings have been developed during this funding period. Ceramic coatings were developed for flexible insulations as well as for low density ceramic insulators. Chemical vapor deposition processes were established for the fabrication of ceramic matrix composites. Experimental testing and characterization of these materials has been carried out in the NASA Ames Research Center Thermophysics Facilities and in the Ames time-of-flight mass spectrometer facility. By means of computation, we have been better able to understand the flow structure and properties of the TPS components and to estimate the aerothermal heating, stress, ablation rate, thermal response, and shape change on the surfaces of TPS. In addition, work for the computational surface thermochemistry project has included modification of existing computer codes and creating new codes to model material response and shape change on atmospheric entry vehicles in a variety of environments (e.g., earth and Mars atmospheres).

Optimization and Characterization of Preceramic Inks for Direct Ink Writing of Ceramic Matrix Composite Structures

PubMed Central

Maden, Halide Selin; Wahl, Larissa; Baliello, Andrea

2018-01-01

In a previous work, an ink based on a preceramic polymer, SiC fillers, and chopped carbon fibers was proposed for the production of Ceramic Matrix Composite (CMC) structures by Direct Ink Writing (DIW) and subsequent pyrolysis. Thanks to the shear stresses generated at the nozzle tip during extrusion, carbon fibers can be aligned along the printing direction. Fumed silica was added to the ink in order to enhance its rheological properties; however, the printed structures still showed some deformation in the Z direction. In this work, a second ink was successfully developed to limit deformation and at the same time avoid the addition of fumed silica, which limited the potential temperature of application of the composites. Instead, the positive role of the preceramic polymer on the ink rheology was exploited by increasing its concentration in the ink. Rheological characterization carried out on both inks confirmed that they possessed Bingham shear thinning behavior and fast viscosity recovery. Single filaments with different diameters (~310 µm and ~460 µm) were produced with the latter ink by DIW and subsequent pyrolysis. Tested under a four-point flexural test, the filaments showed a mean flexural strength above 30 MPa, graceful failure, and fiber pull-out. The results of this work suggest that CMC components can effectively be fabricated via DIW of a preceramic ink with embedded short fibers; the preceramic polymer is able to provide the desired rheology for the process and to develop a dense matrix capable of incorporating both fibers and ceramic particles, whereas the fibers addition contributes to an increase of the fracture toughness of the material and to the development of a graceful failure mode. PMID:29597310

Processing and characterization of boron carbide-hafnium diboride ceramics

NASA Astrophysics Data System (ADS)

Brown-Shaklee, Harlan James

Hafnium diboride based ceramics are promising candidate materials for advanced aerospace and nuclear reactor components. The effectiveness of boron carbide and carbon as HfB2 sintering additives was systematically evaluated. In the first stage of the research, boron carbide and carbon additives were found to improve the densification behavior of milled HfB2 powder in part by removing oxides at the HfB2 surface during processing. Boron carbide additives reduced the hot pressing temperature of HfB2 by 150°C compared to carbon, which reduced the hot pressing temperature by ˜50°C. Reduction of oxide impurities alone could not explain the difference in sintering enhancement, however, and other mechanisms of enhancement were evaluated. Boron carbides throughout the homogeneity range were characterized to understand other mechanisms of sintering enhancement in HfB2. Heavily faulted carbon rich and boron rich boron carbides were synthesized for addition to HfB2. The greatest enhancement to densification was observed in samples containing boron- and carbon-rich compositions whereas B6.5 C provided the least enhancement to densification. It is proposed that carbon rich and boron rich boron carbides create boron and hafnium point defects in HfB2, respectively, which facilitate densification. Evaluation of the thermal conductivity (kth) between room temperature and 2000°C suggested that the stoichiometry of the boron carbide additives did not significantly affect kth of HfB2-BxC composites. The improved sinterability and the high kth (˜110 W/m-K at 300K and ˜90 W/m-K at 1000°C ) of HfB2-BxC ceramics make them excellent candidates for isotopically enriched reactor control materials.

Optimization and Characterization of Preceramic Inks for Direct Ink Writing of Ceramic Matrix Composite Structures.

PubMed

Franchin, Giorgia; Maden, Halide Selin; Wahl, Larissa; Baliello, Andrea; Pasetto, Marco; Colombo, Paolo

2018-03-28

In a previous work, an ink based on a preceramic polymer, SiC fillers, and chopped carbon fibers was proposed for the production of Ceramic Matrix Composite (CMC) structures by Direct Ink Writing (DIW) and subsequent pyrolysis. Thanks to the shear stresses generated at the nozzle tip during extrusion, carbon fibers can be aligned along the printing direction. Fumed silica was added to the ink in order to enhance its rheological properties; however, the printed structures still showed some deformation in the Z direction. In this work, a second ink was successfully developed to limit deformation and at the same time avoid the addition of fumed silica, which limited the potential temperature of application of the composites. Instead, the positive role of the preceramic polymer on the ink rheology was exploited by increasing its concentration in the ink. Rheological characterization carried out on both inks confirmed that they possessed Bingham shear thinning behavior and fast viscosity recovery. Single filaments with different diameters (~310 µm and ~460 µm) were produced with the latter ink by DIW and subsequent pyrolysis. Tested under a four-point flexural test, the filaments showed a mean flexural strength above 30 MPa, graceful failure, and fiber pull-out. The results of this work suggest that CMC components can effectively be fabricated via DIW of a preceramic ink with embedded short fibers; the preceramic polymer is able to provide the desired rheology for the process and to develop a dense matrix capable of incorporating both fibers and ceramic particles, whereas the fibers addition contributes to an increase of the fracture toughness of the material and to the development of a graceful failure mode.

Characterization of the Microstructures of Various Materials.

DTIC Science & Technology

1984-04-01

has been reviewed and is approved for publication. CHARLES R. UNDERWOOD Manager, Characterization Facility Structural Metals Branch Metals & Ceramics ...Division FOR THE COMMANDER GAIL E. EICHELMAN Chief, Structural Metals Branch Metals & Ceramics Division "If your address has changed, if you wish to...Electroplating Set-up, (b) P&W RSR185 Ni-Ni Plate , (c) Powder Distribution in 3-mill Disk. 12 2 Schematic Representation of Voltage-Current Characteristics for

Ceramic and coating applications in the hostile environment of a high temperature hypersonic wind tunnel. [Langley 8-foot high temperature structures tunnel

NASA Technical Reports Server (NTRS)

Puster, R. L.; Karns, J. R.; Vasquez, P.; Kelliher, W. C.

1981-01-01

A Mach 7, blowdown wind tunnel was used to investigate aerothermal structural phenomena on large to full scale high speed vehicle components. The high energy test medium, which provided a true temperature simulation of hypersonic flow at 24 to 40 km altitude, was generated by the combustion of methane with air at high pressures. Since the wind tunnel, as well as the models, must be protected from thermally induced damage, ceramics and coatings were used extensively. Coatings were used both to protect various wind tunnel components and to improve the quality of the test stream. Planned modifications for the wind tunnel included more extensive use of ceramics in order to minimize the number of active cooling systems and thus minimize the inherent operational unreliability and cost that accompanies such systems. Use of nonintrusive data acquisition techniques, such as infrared radiometry, allowed more widespread use of ceramics for models to be tested in high energy wind tunnels.

Advanced ceramic coating development for industrial/utility gas turbine applications

NASA Technical Reports Server (NTRS)

Andersson, C. A.; Lau, S. K.; Bratton, R. J.; Lee, S. Y.; Rieke, K. L.; Allen, J.; Munson, K. E.

1982-01-01

The effects of ceramic coatings on the lifetimes of metal turbine components and on the performance of a utility turbine, as well as of the turbine operational cycle on the ceramic coatings were determined. When operating the turbine under conditions of constant cooling flow, the first row blades run 55K cooler, and as a result, have 10 times the creep rupture life, 10 times the low cycle fatigue life and twice the corrosion life with only slight decreases in both specific power and efficiency. When operating the turbine at constant metal temperature and reduced cooling flow, both specific power and efficiency increases, with no change in component lifetime. The most severe thermal transient of the turbine causes the coating bond stresses to approach 60% of the bond strengths. Ceramic coating failures was studied. Analytic models based on fracture mechanics theories, combined with measured properties quantitatively assessed both single and multiple thermal cycle failures which allowed the prediction of coating lifetime. Qualitative models for corrosion failures are also presented.

Thermal and Environmental Barrier Coatings for Advanced Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Miller, Robert A.

2005-01-01

Ceramic thermal and environmental barrier coatings (T/EBCs) will play a crucial role in advanced gas turbine engine systems because of their ability to significantly increase engine operating temperatures and reduce cooling requirements, thus help achieve engine low emission and high efficiency goals. Advanced T/EBCs are being developed for the low emission SiC/SiC ceramic matrix composite (CMC) combustor applications by extending the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water vapor containing combustion environments. Low conductivity thermal barrier coatings (TBCs) are also being developed for metallic turbine airfoil and combustor applications, providing the component temperature capability up to 1650 C (3000 F). In this paper, ceramic coating development considerations and requirements for both the ceramic and metallic components will be described for engine high temperature and high-heat-flux applications. The underlying coating failure mechanisms and life prediction approaches will be discussed based on the simulated engine tests and fracture mechanics modeling results.

Robust Joining and Integration Technologies for Advanced Metallic, Ceramic, and Composite Systems

NASA Technical Reports Server (NTRS)

Singh, M.; Shpargel, Tarah; Morscher, Gregory N.; Halbig, Michael H.; Asthana, Rajiv

2006-01-01

Robust integration and assembly technologies are critical for the successful implementation of advanced metallic, ceramic, carbon-carbon, and ceramic matrix composite components in a wide variety of aerospace, space exploration, and ground based systems. Typically, the operating temperature of these components varies from few hundred to few thousand Kelvin with different working times (few minutes to years). The wide ranging system performance requirements necessitate the use of different integration technologies which includes adhesive bonding, low temperature soldering, active metal brazing, diffusion bonding, ARCJoinT, and ultra high temperature joining technologies. In this presentation, a number of joining examples and test results will be provided related to the adhesive bonding and active metal brazing of titanium to C/C composites, diffusion bonding of silicon carbide to silicon carbide using titanium interlayer, titanium and hastelloy brazing to silicon carbide matrix composites, and ARCJoinT joining of SiC ceramics and SiC matrix composites. Various issues in the joining of metal-ceramic systems including thermal expansion mismatch and resulting residual stresses generated during joining will be discussed. In addition, joint design and testing issues for a wide variety of joints will be presented.

Organic-inorganic composites designed for biomedical applications.

PubMed

Miyazaki, Toshiki; Ishikawa, Kunio; Shirosaki, Yuki; Ohtsuki, Chikara

2013-01-01

Several varieties of ceramics, such as Bioglass-type glasses, sintered hydroxyapatite and glass-ceramic A-W, exhibit specific biological affinity, i.e., direct bonding to surrounding bone, when implanted in bony defects. These bone-bonding ceramics are called bioactive ceramics and are utilized as important bone substitutes in the medical field. However, there is a limitation to their clinical applications because of their inappropriate mechanical properties. Natural bone takes a kind of organic-inorganic composite, where apatite nanocrystals are precipitated on collagen fibers. Therefore, problems with the bioactive ceramics can be solved by material design based on the composites. In this paper, current research topics on the development of bioactive organic-inorganic composites inspired by actual bone microstructure have been reviewed in correlation with preparation methods and various properties. Several kinds of inorganic components have been found to exhibit bioactivity in the body environment. Combination of the inorganic components with various organic polymers enables the development of bioactive organic-inorganic composites. In addition, novel biomedical applications of the composites to drug delivery systems, scaffolds for tissue regeneration and injectable biomaterials are available by combining drugs or biological molecules with appropriate control of its microstructure.

Utilisation of drinking water treatment sludge for the manufacturing of ceramic products

NASA Astrophysics Data System (ADS)

Kizinievič, O.; Kizinievič, V.

2017-10-01

The influence of the additive of drinking water treatment sludge on the physical and mechanical properties, structural parameters, microstructure of the ceramic products is analysed in the research. Drinking water treatment sludge is renewable, environmentally-friendly, economical additive saving expensive natural raw materials when introduced into the ceramic products. The main drinking water treatment sludge component is amorphous Fe2O3 (70%). Formation masses are prepared by incorporating from 5 % to 60 % of drinking water treatment additive and by burning out at the temperature 1000 °C. Investigation showed that the physical and mechanical properties, microstructure of the ceramic bodies vary depending on the amount of drinking water treatment additive incorporated. In addition, drinking water treatment additive affects the ceramic body as a pigment that dyes the ceramic body in darker red colour.

Predictive Surface Roughness Model for End Milling of Machinable Glass Ceramic

NASA Astrophysics Data System (ADS)

Mohan Reddy, M.; Gorin, Alexander; Abou-El-Hossein, K. A.

2011-02-01

Advanced ceramics of Machinable glass ceramic is attractive material to produce high accuracy miniaturized components for many applications in various industries such as aerospace, electronics, biomedical, automotive and environmental communications due to their wear resistance, high hardness, high compressive strength, good corrosion resistance and excellent high temperature properties. Many research works have been conducted in the last few years to investigate the performance of different machining operations when processing various advanced ceramics. Micro end-milling is one of the machining methods to meet the demand of micro parts. Selecting proper machining parameters are important to obtain good surface finish during machining of Machinable glass ceramic. Therefore, this paper describes the development of predictive model for the surface roughness of Machinable glass ceramic in terms of speed, feed rate by using micro end-milling operation.

Attrition resistant fluidizable reforming catalyst

DOEpatents

Parent, Yves O [Golden, CO; Magrini, Kim [Golden, CO; Landin, Steven M [Conifer, CO; Ritland, Marcus A [Palm Beach Shores, FL

2011-03-29

A method of preparing a steam reforming catalyst characterized by improved resistance to attrition loss when used for cracking, reforming, water gas shift and gasification reactions on feedstock in a fluidized bed reactor, comprising: fabricating the ceramic support particle, coating a ceramic support by adding an aqueous solution of a precursor salt of a metal selected from the group consisting of Ni, Pt, Pd, Ru, Rh, Cr, Co, Mn, Mg, K, La and Fe and mixtures thereof to the ceramic support and calcining the coated ceramic in air to convert the metal salts to metal oxides.

In-situ formation of multiphase air plasma sprayed barrier coatings for turbine components

DOEpatents

Subramanian, Ramesh

2001-01-01

A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base, planar-grained thermal barrier layer (28) applied by air plasma spraying on the alloy surface, where a heat resistant ceramic oxide overlay material (32') covers the bottom thermal barrier coating (28), and the overlay material is the reaction product of the precursor ceramic oxide overlay material (32) and the base thermal barrier coating material (28).

Thick ceramic coating development for industrial gas turbines - A program plan

NASA Technical Reports Server (NTRS)

Vogan, J. W.; Stetson, A. R.

1979-01-01

A program plan on a NASA-Lewis funded program is presented, in which effectiveness of thick ceramic coatings in preventing hot corrosion and in providing thermal insulation to gas turbine engine components are to be investigated. Preliminary analysis of the benefit of the thermal insulating effect of this coating on decreasing cooling air and simplifying component design appears very encouraging. The program is in the preliminary stages of obtaining starting materials and establishing procedures. Numerous graphs, tables and photographs are included.

Gradient composite metal-ceramic foam as supportive component for planar SOFCs and MIEC membranes

NASA Astrophysics Data System (ADS)

Smorygo, Oleg; Mikutski, Vitali; Marukovich, Alexander; Sadykov, Vladislav; Usoltsev, Vladimir; Mezentseva, Natalia; Borodinecs, Anatolijs; Bobrenok, Oleg

2011-06-01

A novel approach to the design of planar gradient porous supports for the thin-film SOFCs and MIEC membranes is described. The support's thermal expansion is controlled by the creation of a two-component composite metal-ceramic foam structure. Thin MIEC membranes and SOFCs were prepared on the composite supports by the layerwise deposition of composite functional layers including complex fluorites and perovskites. Lab-scale studies demonstrated promising performance of both MIEC membrane and SOFC.

Growth and Characterization of Nanostructured Glass Ceramic Scintillators for Miniature High-Energy Radiation Sensors

DTIC Science & Technology

2013-10-01

public release; distribution is unlimited. October 2013 HDTRA1-03-D-0009 Mansoor Sheik- Bahae Prepared by: OVPR...Characterization of Nanostructured Glass Ceramic Scintillators for Miniature High-Energy Radiation Sensors HDTRA01-03-D-0009 Mansoor Sheik- Bahae 26 OVPR...Table of Contents…………………………………………………………….3 I . Synthesis of Nano-Structured Glass Ceramic…..……………………………4 II. Characterize Structure and

Advanced SiC/SiC Ceramic Composites For Gas-Turbine Engine Components

NASA Technical Reports Server (NTRS)

Yun, H. M.; DiCarlo, J. A.; Easler, T. E.

2004-01-01

NASA Glenn Research Center (GRC) is developing a variety of advanced SiC/SiC ceramic composite (ASC) systems that allow these materials to operate for hundreds of hours under stress in air at temperatures approaching 2700 F. These SiC/SiC composite systems are lightweight (approximately 30% metal density) and, in comparison to monolithic ceramics and carbon fiber-reinforced ceramic composites, are able to reliably retain their structural properties for long times under aggressive gas-turbine engine environments. The key for the ASC systems is related first to the NASA development of the Sylramic-iBN Sic fiber, which displays higher thermal stability than any other SiC- based ceramic fibers and possesses an in-situ grown BN surface layer for higher environmental durability. This fiber is simply derived from Sylramic Sic fiber type that is currently produced at ATK COI Ceramics (COIC). Further capability is then derived by using chemical vapor infiltration (CVI) and/or polymer infiltration and pyrolysis (PIP) to form a Sic-based matrix with high creep and rupture resistance as well as high thermal conductivity. The objectives of this study were (1) to optimize the constituents and processing parameters for a Sylramic-iBN fiber reinforced ceramic composite system in which the Sic-based matrix is formed at COIC almost entirely by PIP (full PIP approach), (2) to evaluate the properties of this system in comparison to other 2700 F Sylramic-iBN systems in which the matrix is formed by full CVI and CVI + PIP, and (3) to examine the pros and cons of the full PIP approach for fabricating hot-section engine components. A key goal is the development of a composite system with low porosity, thereby providing high modulus, high matrix cracking strength, high interlaminar strength, and high thermal conductivity, a major property requirement for engine components that will experience high thermal gradients during service. Other key composite property goals are demonstration at high temperatures of high environmental resistance and high creep resistance, which in turn will result in long component life. Data are presented from a variety of laboratory tests on simple two-dimensional panels that examine these properties and compare the performance of the optimized full PIP system with those of the full CVI and CVI + PIP hybrid systems. Underlying mechanisms for performance differences in the various systems are discussed. Remaining issues for further property enhancement and for application of the full PIP approach for engine components are also discussed, as well as on-going approaches at NASA to solve these issues.

[Comparison of in vivo characteristics of polyethylene wear particles produced by a metal and a ceramic femoral component in total knee replacement].

PubMed

Veigl, D; Vavřík, P; Pokorný, D; Slouf, M; Pavlova, E; Landor, I

2011-01-01

The aim of the study was to evaluate in vivo and compare, in terms of the quality and number of ultra high-molecular polyethylene (UHMWPE) wear particles, total knee replacements of identical construction differing only in the material used for femoral component production, i.e., CoCrMo alloy or ZrO2 ceramics. Samples of peri-prosthetic granuloma tissue were collected in two patients with total knee replacement suffering from implant migration, who were matched in relevant characteristics. The primary knee replacement in Patient 1 with a CoCrMo femoral component was done 7.2 years and in Patient 2 with a ZrO2 implant 6.8 years before this assessment. The polyethylene wear-induced granuloma was analysed by the MORF method enabling us to assess the shape and size of wear debris and the IRc method for assessment of particle concentration. In the granuloma tissue samples of Patient 1, on the average, particles were 0.30 mm in size and their relative volume was 0.19. In the Patient 2 tissue samples, the average size of particles was 0.33 mm and their relative volume was 0.26. There was no significant difference in either particle morphology or their concentration in the granuloma tissue between the two patients. One of the options of how to reduce the production of polyethylene wear particles is to improve the tribological properties of contacting surfaces in total knee replacement by substituting a cobalt-chrome femoral component with a zirconia ceramic femoral component. The previous in vitro testing carried out with a mechanical simulator under conditions approaching real weight-bearing in the human body did show a nearly three-fold decrease in the number of UHMWPE wear particles in zirconia components. The evaluation of granuloma tissue induced by the activity of a real prosthetic joint for nearly seven years, however, did not reveal any great difference in either quality or quantity of polyethylene debris between the two replacements. The difference of surface roughness between CoCrMo (Ra = 0.05) and ZrO2 (Ra = 0.02) components did not play any role in in vivo conditions. CONCLUSIONS In accordance with a previous clinical study, this evaluation of the quality and quantity of UHMWPE wear particles produced by a ceramic femoral component in vivo failed to demonstrate any advantage of zirconia ceramic components over the cobalt-chrome femoral components so far used.

Using Yttra-Stabilized Zirconium Oxide Ceramics to Sense pH and Oxygen in Hydrothermal and Geothermal Applications

NASA Astrophysics Data System (ADS)

Manna, M. F.; Grandstaff, D. E.; Ulmer, G. C.

2002-05-01

Zirconium-Oxide ceramics stabilized with ~8-wt% Yttrium-Oxide can be employed to sense pH in high temperature (>90oC) aqueous environments with an accuracy of 0.05 pH log units (Lvov et al., in press), and to sense the fugacity of oxygen (fO2) in low temperature (>230oC) gaseous environments with an accuracy of 0.2 (fO2) log units. The major components, in two commercially available yttria-stabilized ceramics are yttria ( ~8-wt%) and zirconia ( ~91-wt%) with minor amounts of Ti, Fe and U. The textural differences in the two ceramics produces significantly different emf vs. 10,000/T responses. Response error can be introduced by: the ionic contribution of the softening glass, the catalytic action of the Pt sensor components, and the presence of Ti and Fe in the ceramic, which has been shown to alter the oxygen diffusivity of the ceramic. (Merino et al., 1996) The first type of ceramic contains a 3-dimensionally-continuous Ca-Al-Si feldspathic glass that acts as a sintering aid during manufacturing. The glass, which has a higher ionic conductivity than the zirconia ceramic, reduces the bulk resistivity and induces an error over the temperature ranges representing the softening point of the glass. The glass also reduces durability of the ceramic. When the glass hydrates it produces zeolites, which grow primarily in the triple-grain-junctions of the ceramic. Thus mechanically weakening the ceramic generating electronic, ionic and mechanical stability problems. The second type of ceramic contains no grain boundary glass, but does contain discrete silicate phases (such as diopside, wollastonite, periclase, silica, etc.) in the triple-grain-junctions. Because there is no inter-granular glass, the type two ceramic does have a greater bulk resistivity compared with the type one ceramic. In a gas-sensing configuration, resistivity has been shown to affect the minimum temperature of sensor operation. A sensor with a higher bulk resistivity must reach a higher minimum temperature before the sensor will sense oxygen. Literature suggests that the same is true for the sensor in its aqueous pH configuration. In addition to the mechanical degradation, there are also chemical leaching issues with both ceramics. While zirconium is relatively unleachable in its pure form, the addition of yttria, while creating the necessary lattice defects, increases the vulnerability of the solid solution grains to acidic solutions. This, creates ceramic durability problems during long-term down-hole operation. The ceramics do function well as a sensor and can produce highly accurate results (with calibration) and if the durability issues are taken into account, the ceramic sensor could be a highly desirable for many high temperature geologic and industrial applications.

A review of failure models for unidirectional ceramic matrix composites under monotonic loads

NASA Technical Reports Server (NTRS)

Tripp, David E.; Hemann, John H.; Gyekenyesi, John P.

1989-01-01

Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by trial and error since the emphasis of feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.

Glass and ceramics. [lunar resources

NASA Technical Reports Server (NTRS)

Haskin, Larry A.

1992-01-01

A variety of glasses and ceramics can be produced from bulk lunar materials or from separated components. Glassy products include sintered regolith, quenched molten basalt, and transparent glass formed from fused plagioclase. No research has been carried out on lunar material or close simulants, so properties are not known in detail; however, common glass technologies such as molding and spinning seem feasible. Possible methods for producing glass and ceramic materials are discussed along with some potential uses of the resulting products.

Rapid Prototyping

NASA Technical Reports Server (NTRS)

1999-01-01

Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

Life prediction methodology for ceramic components of advanced heat engines. Phase 1: Volume 2, Appendices

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

NONE

1995-03-01

This volume presents the following appendices: ceramic test specimen drawings and schematics, mixed-mode and biaxial stress fracture of structural ceramics for advanced vehicular heat engines (U. Utah), mode I/mode II fracture toughness and tension/torsion fracture strength of NT154 Si nitride (Brown U.), summary of strength test results and fractography, fractography photographs, derivations of statistical models, Weibull strength plots for fast fracture test specimens, and size functions.

Formation of Green compact structure of low-temperature ceramics with taking into account the thermal degradation of the binder

NASA Astrophysics Data System (ADS)

Tovpinets, A. O.; Leytsin, V. N.; Dmitrieva, M. A.; Ivonin, I. V.; Ponomarev, S. V.

2017-12-01

The solution of the tasks in the field of creating and processing materials for additive technologies requires the development of a single theory of materials for various applications and processes. A separate class of materials that are promising for use in additive technologies includes materials whose consolidation is ensured by the presence of low-melting components in the initial mixture which form a matrix at a temperature not exceeding the melting point, recrystallization or destruction of any of the responsible refractory components of the initial dispersion. The study of the contribution of the binder thermal destruction to the structure and phase composition of the initial compact of the future composite is essential for the development of modern technologies for the synthesis of low-temperature ceramics. This paper investigates the effect of the thermal destruction of a binder on the formation of a green compact of low-temperature ceramics and the structural-mechanical characteristics of sintered ceramics. The approach proposed in Ref. [1] for evaluating the structure and physical characteristics of sintered low-temperature ceramics is improved to clarify the structure of green compacts obtained after thermal destruction of the polymer binder, with taking into account the pores formed and the infusible residue. The obtained results enable a more accurate prediction of thermal stresses in the matrix of sintered ceramics and serve as a basis for optimization.

Anisotropic and Hierarchical Porosity in Multifunctional Ceramics

NASA Astrophysics Data System (ADS)

Lichtner, Aaron Zev

The performance of multifunctional porous ceramics is often hindered by the seemingly contradictory effects of porosity on both mechanical and non-structural properties and yet a sufficient body of knowledge linking microstructure to these properties does not exist. Using a combination of tailored anisotropic and hierarchical materials, these disparate effects may be reconciled. In this project, a systematic investigation of the processing, characterization and properties of anisotropic and isotropic hierarchically porous ceramics was conducted. The system chosen was a composite ceramic intended as the cathode for a solid oxide fuel cell (SOFC). Comprehensive processing investigations led to the development of approaches to make hierarchical, anisotropic porous microstructures using directional freeze-casting of well dispersed slurries. The effect of all the important processing parameters was investigated. This resulted in an ability to tailor and control the important microstructural features including the scale of the microstructure, the macropore size and total porosity. Comparable isotropic porous ceramics were also processed using fugitive pore formers. A suite of characterization techniques including x-ray tomography and 3-D sectional scanning electron micrographs (FIB-SEM) was used to characterize and quantify the green and partially sintered microstructures. The effect of sintering temperature on the microstructure was quantified and discrete element simulations (DEM) were used to explain the experimental observations. Finally, the comprehensive mechanical properties, at room temperature, were investigated, experimentally and using DEM, for the different microstructures.

Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna; Kiser, Doug; Wiesner, Valerie L.

2016-01-01

This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiCSiC Ceramic Matrix Composite (CMC) components for next generation turbine engines. The emphasis has been placed on the current design challenges of the 2700F environmental barrier coatings; coating processing and integration with SiCSiC CMCs and component systems; and performance evaluation and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements through advanced compositions and architecture designs, as shown in recent simulated engine high heat flux, combustion environment, in conjunction with mechanical creep and fatigue loading testing conditions.

Synthesis and characterization of a novel polyborosilazane for SiBNC ceramic

NASA Astrophysics Data System (ADS)

Zhang, C. Y.; Liu, Y.; Han, K. Q.; Chang, X. F.; Yu, M. H.

2018-05-01

A novel polyborosilazane (PBSZ) for preparing SiBNC ceramics was successfully synthesized via co-condensation approach using tetrachlorosilan (SiCl4), trichloride (BCl3) and propylamine (C3H7NH2) as starting materials. After pyrolysis of these precursors, amorphous SiBNC ceramics were obtained. The chemical composition, structure and thermal stability of the synthesized PBSZ precursor and SiBNC ceramics were analyzed by using FT-IR, NMR, TGA and XRD methods. The results indicated that the PBSZ contained the major framework of –Si-N-B- and six-membered boron-nitrogen rings. The PBSZ precursor had an approximately ceramic yield of 63 wt% prolyzed at 900°C in nitrogen atmosphere. The SiBNC ceramics shows excellent oxidation resistance and maintained amorphous up to 1600°C.

Development of sensors for ceramic components in advanced propulsion systems

NASA Technical Reports Server (NTRS)

Atkinson, William H.; Cyr, M. A.; Strange, R. R.

1994-01-01

The 'Development of Sensors for Ceramics Components in Advanced Propulsion Systems' program was divided into two phases. The objectives of Phase 1 were to analyze, evaluate and recommend sensor concepts for the measurement of surface temperature, strain and heat flux on ceramic components for advanced propulsion systems. The results of this effort were previously published in NASA CR-182111. As a result of Phase 1, three approaches were recommended for further development: pyrometry, thin-film sensors, and thermographic phosphors. The objectives of Phase 2 were to fabricate and conduct laboratory demonstration tests of these systems. A summary report of the Phase 2 effort, together with conclusions and recommendations for each of the categories evaluated, has been submitted to NASA. Emittance tests were performed on six materials furnished by NASA Lewis Research Center. Measurements were made of various surfaces at high temperature using a Thermogage emissometer. This report describes the emittance test program and presents a summary of the results.

Characterization of Mechanical Damage Mechanisms in Ceramic and Polymeric Matrix Composite Materials

DTIC Science & Technology

1991-11-01

microplasticity is a vital factor in the compressive failure of even these very hard materials under essentially all conditions (temperature, strain rate...OF CONTENTS Pag= The Compressive Strength of Strong Ceramics: Microplasticity Versus 1 Microfracture Abstract 1 1. Introduction 2 2. Hardness 3 3...Acknowledgements 51 References 51 COATVANOORD1 24-91CDXC 11. LIST OF FIGURES Figure Page The Compressive Strength of Strong Ceramics: Microplasticity Versus

Morphological characterization of ceramic fillers made from Indonesian natural sand as restorative dental materials

NASA Astrophysics Data System (ADS)

Karlina, E.; Susra, S.; Fatmala, Y.; Hartoyo, H. M.; Takarini, V.; Usri, K.; Febrida, R.; Djustiana, N.; Panatarani, C.; Joni, I. M.

2018-02-01

Dental composite as restorative dental materials can be reinforced using ceramic fillers. Homogeneous distribution of filler particles shall improve its mechanical properties. This paper presents the results of the preliminary study on the ZrO2-Al2O3-SiO2 ceramic fillers made from Indonesian natural sand that can increase the mechanical properties of dental composite. The synthesis was done using zirconium silicate sand (ZrSiO4) and aluminium oxide (Al2O3) precursors, which dissolved together with 70:30 weight ratios. Two types of sand were used: (1) manufactured sand (mesh #80) and (2) natural sand (mesh #400). The samples then heated in the furnace at 1100 °C for 8 hours. The morphological characterization was then evaluated using JEOL Scanning Electron Microscope (SEM) for the surface structure that analyze particles size and distribution. Ceramic fillers made from natural sand is homogenous, well distributed with average particle size of 5-10 µm. Comparably, ceramic filler made from the manufactured sand is heterogeneous, poorly distributed and appear as agglomerates with average particle size are 30-50 µm. The results suggest that ceramic fillers made from natural sand demonstrate better character to represent as a functional restorative dental material.

Fabrication of Carbon Nanotube - Chromium Carbide Composite Through Laser Sintering

NASA Astrophysics Data System (ADS)

Liu, Ze; Gao, Yibo; Liang, Fei; Wu, Benxin; Gou, Jihua; Detrois, Martin; Tin, Sammy; Yin, Ming; Nash, Philip; Tang, Xiaoduan; Wang, Xinwei

2016-03-01

Ceramics often have high hardness and strength, and good wear and corrosion resistance, and hence have many important applications, which, however, are often limited by their poor fracture toughness. Carbon nanotubes (CNTs) may enhance ceramic fracture toughness, but hot pressing (which is one typical approach of fabricating CNT-ceramic composites) is difficult to apply for applications that require localized heat input, such as fabricating composites as surface coatings. Laser beam may realize localized material sintering with little thermal effect on the surrounding regions. However, for the typical ceramics for hard coating applications (as listed in Ref.[1]), previous work on laser sintering of CNT-ceramic composites with mechanical property characterizations has been very limited. In this paper, research work has been reported on the fabrication and characterization of CNT-ceramic composites through laser sintering of mixtures of CNTs and chromium carbide powders. Under the studied conditions, it has been found that laser-sintered composites have a much higher hardness than that for plasma-sprayed composites reported in the literature. It has also been found that the composites obtained by laser sintering of CNTs and chromium carbide powder mixtures have a fracture toughness that is ~23 % higher than the material obtained by laser sintering of chromium carbide powders without CNTs.

Silicon Nitride Plates for Turbine Blade Application: FEA and NDE Assessment

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali; Baaklini, George Y.; Bhatt, Ramakrishna T.

2001-01-01

Engine manufacturers are continually attempting to improve the performance and the overall efficiency of internal combustion engines. The thermal efficiency is typically improved by raising the operating temperature of essential engine components in the combustion area. This reduces the heat loss to a cooling system and allows a greater portion of the heat to be used for propulsion. Further improvements can be achieved by diverting part of the air from the compressor, which would have been used in the combustor for combustion purposes, into the turbine components. Such a process is called active cooling. Increasing the operating temperature, decreasing the cooling air, or both can improve the efficiency of the engine. Furthermore, lightweight, strong, tough hightemperature materials are required to complement efficiency improvement for nextgeneration gas turbine engines that can operate with minimum cooling. Because of their low-density, high-temperature strength, and thermal conductivity, ceramics are being investigated as potential materials for replacing ordinary metals that are currently used for engine hot section components. Ceramic structures can withstand higher operating temperatures and other harsh environmental factors. In addition, their low densities relative to metals helps condense component mass (ref. 1). The objectives of this program at the NASA Glenn Research Center are to develop manufacturing technology, a thermal barrier coating/environmental barrier coating (TBC/EBC), and an analytical modeling capability to predict thermomechanical stresses, and to do minimal burner rig tests of silicon nitride (Si3N4) and SiC/SiC turbine nozzle vanes under simulated engine conditions. Furthermore, and in support of the latter objectives, an optimization exercise using finite element analysis and nondestructive evaluation (NDE) was carried out to characterize and evaluate silicon nitride plates with cooling channels.

Preparation and characterization of a novel willemite bioceramic.

PubMed

Zhang, Meili; Zhai, Wanyin; Chang, Jiang

2010-04-01

Willemite (Zn(2)SiO(4)) ceramics were prepared by sintering the willemite green compacts. The effects of sintering temperature on the linear shrinkage, porosity and mechanical strength of the ceramics were examined. With the sintering temperature increased, the linear shrinkage of the ceramics increased and the porosity decreased. When sintered at 1,300 degrees C, willemite ceramics showed mechanical properties of the same order of magnitude as values for human cortical bone, as measured by bending strength (91.2 +/- 4.2 MPa) and Young's modulus (37.5 +/- 1.5 GPa). In addition, the adhesion and proliferation of rabbit bone marrow stromal cells (BMSCs) on willemite ceramics was investigated. The results showed that the ceramics supported cell adhesion and stimulated the proliferation. All these findings suggest that willemite ceramics possess suitable mechanical properties and favorable biocompatibility and might be a promising biomaterial for bone implant applications.

Mechanical properties of a new mica-based machinable glass ceramic for CAD/CAM restorations.

PubMed

Thompson, J Y; Bayne, S C; Heymann, H O

1996-12-01

Machinable ceramics (Vita Mark II and Dicor MGC) exhibit good short-term clinical performance, but long-term in vivo fracture resistance is still being monitored. The relatively low fracture toughness of currently available machinable ceramics restricts their use to conservative inlays and onlays. A new machinable glass ceramic (MGC-F) has been developed (Corning Inc.) with enhanced fluorescence and machinability. The purpose of this study was to characterize and compare key mechanical properties of MGC-F to Dicor MGC-Light, Dicor MGC-Dark, and Vita Mark II glass ceramics. The mean fracture toughness and indented biaxial flexure strength of MGC-F were each significantly greater (p < or = 0.01) than that of Dicor MGC-Light, Dicor MGC-Dark, and Vita Mark II ceramic materials. The results of this study indicate the potential for better in vivo fracture resistance of MGC-F compared with existing machinable ceramic materials for CAD/CAM restorations.

Preparation, characterization and application of novel proton conducting ceramics

NASA Astrophysics Data System (ADS)

Wang, Siwei

Due to the immediate energy shortage and the requirement of environment protection nowadays, the efficient, effective and environmental friendly use of current energy sources is urgent. Energy conversion and storage is thus an important focus both for industry and academia. As one of the hydrogen energy related materials, proton conducting ceramics can be applied in solid oxide fuel cells and steam electrolysers, as well as high temperature hydrogen separation membranes and hydrogen sensors. For most of the practical applications, both high proton conductivity and chemical stability are desirable. However, the state-of-the-art proton conducting ceramics are facing great challenges in simultaneously fulfilling conductivity and stability requirements for practical applications. Consequently, understanding the properties for the proton conducting ceramics and developing novel materials that possess both high proton conductivity and enhanced chemical stability have both scientific and practical significances. The objective of this study is to develop novel proton conducting ceramics, either by evaluating the doping effects on the state-of-the-art simple perovskite structured barium cerates, or by investigating novel complex perovskite structured Ba3Ca1.18Nb1.82O 9-delta based proton conductors as potential proton conducting ceramics with improved proton conductivity and enhanced chemical stability. Different preparation methods were compared, and their influence on the structure, including the bulk and grain boundary environment has been investigated. In addition, the effects of microstructure on the electrical properties of the proton conducting ceramics have also been characterized. The solid oxide fuel cell application for the proton conducting ceramics performed as electrolyte membranes has been demonstrated.

Interdisciplinary research on the nature and properties of ceramic materials

NASA Technical Reports Server (NTRS)

1980-01-01

Several investigations concerning the properties and processing of brittle ceramic materials as related to design considerations are briefly described. Surface characterization techniques, fractography, high purity materials, creep properties, impact and thermal shock resistance, and reaction bonding are discussed.

Electrospun Ceramic Nanofiber Mats Today: Synthesis, Properties, and Applications

PubMed Central

Esfahani, Hamid; Ramakrishna, Seeram

2017-01-01

Ceramic nanofibers (NFs) have recently been developed for advanced applications due to their unique properties. In this article, we review developments in electrospun ceramic NFs with regard to their fabrication process, properties, and applications. We find that surface activity of electrospun ceramic NFs is improved by post pyrolysis, hydrothermal, and carbothermal processes. Also, when combined with another surface modification methods, electrospun ceramic NFs result in the advancement of properties and widening of the application domains. With the decrease in diameter and length of a fiber, many properties of fibrous materials are modified; characteristics of such ceramic NFs are different from their wide and long (bulk) counterparts. In this article, electrospun ceramic NFs are reviewed with an emphasis on their applications as catalysts, membranes, sensors, biomaterials, fuel cells, batteries, supercapacitors, energy harvesting systems, electric and magnetic parts, conductive wires, and wearable electronic textiles. Furthermore, properties of ceramic nanofibers, which enable the above applications, and techniques to characterize them are briefly outlined. PMID:29077074

Electrospun Ceramic Nanofiber Mats Today: Synthesis, Properties, and Applications.

PubMed

Esfahani, Hamid; Jose, Rajan; Ramakrishna, Seeram

2017-10-27

Ceramic nanofibers (NFs) have recently been developed for advanced applications due to their unique properties. In this article, we review developments in electrospun ceramic NFs with regard to their fabrication process, properties, and applications. We find that surface activity of electrospun ceramic NFs is improved by post pyrolysis, hydrothermal, and carbothermal processes. Also, when combined with another surface modification methods, electrospun ceramic NFs result in the advancement of properties and widening of the application domains. With the decrease in diameter and length of a fiber, many properties of fibrous materials are modified; characteristics of such ceramic NFs are different from their wide and long (bulk) counterparts. In this article, electrospun ceramic NFs are reviewed with an emphasis on their applications as catalysts, membranes, sensors, biomaterials, fuel cells, batteries, supercapacitors, energy harvesting systems, electric and magnetic parts, conductive wires, and wearable electronic textiles. Furthermore, properties of ceramic nanofibers, which enable the above applications, and techniques to characterize them are briefly outlined.

NDE of ceramics and ceramic composites

NASA Technical Reports Server (NTRS)

Vary, Alex; Klima, Stanley J.

1991-01-01

Although nondestructive evaluation (NDE) techniques for ceramics are fairly well developed, they are difficult to apply in many cases for high probability detection of the minute flaws that can cause failure in monolithic ceramics. Conventional NDE techniques are available for monolithic and fiber reinforced ceramic matrix composites, but more exact quantitative techniques needed are still being investigated and developed. Needs range from flaw detection to below 100 micron levels in monolithic ceramics to global imaging of fiber architecture and matrix densification anomalies in ceramic composites. NDE techniques that will ultimately be applicable to production and quality control of ceramic structures are still emerging from the lab. Needs are different depending on the processing stage, fabrication method, and nature of the finished product. NDE techniques are being developed in concert with materials processing research where they can provide feedback information to processing development and quality improvement. NDE techniques also serve as research tools for materials characterization and for understanding failure processes, e.g., during thermomechanical testing.

Light-weight black ceramic insulation

NASA Technical Reports Server (NTRS)

Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

2003-01-01

Ultra-high temperature, light-weight, black ceramic insulation having a density ranging from about 0.12 g/cc. to 0.6 g/cc. such as ceramic tile is obtained by pyrolyzing siloxane gels derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes also may contain an effective amount of a mono- or trialkoxy silane to obtain the siloxane gels. The siloxane gels are dried at ambient temperatures and pressures to form siloxane ceramic precursors without significant shrinkage. The siloxane ceramic precursors are subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C., and particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

Nano-ceramics and method thereof

DOEpatents

Satcher, Jr., Joe H.; Gash, Alex [Livermore, CA; Simpson, Randall [Livermore, CA; Landingham, Richard [Livermore, CA; Reibold, Robert A [Salida, CA

2006-08-08

Disclosed herein is a method to produce ceramic materials utilizing the sol-gel process. The methods enable the preparation of intimate homogeneous dispersions of materials while offering the ability to control the size of one component within another. The method also enables the preparation of materials that will densify at reduced temperature.

Method of preparing thin porous sheets of ceramic material

DOEpatents

Swarr, Thomas E.; Nickols, Richard C.; Krasij, Myron

1987-03-24

A method of forming thin porous sheets of ceramic material for use as electrodes or other components in a molten carbonate fuel cell is disclosed. The method involves spray drying a slurry of fine ceramic particles in liquid carrier to produce generally spherical agglomerates of high porosity and a rough surface texture. The ceramic particles may include the electrode catalyst and the agglomerates can be calcined to improve mechanical strength. After slurrying with suitable volatile material and binder tape casting is used to form sheets that are sufficiently strong for further processing and handling in the assembly of a high temperature fuel cell.

Freeze Tape Casting of Functionally Graded Porous Ceramics

NASA Technical Reports Server (NTRS)

Sofie, Stephen W.

2007-01-01

Freeze tape casting is a means of making preforms of ceramic sheets that, upon subsequent completion of fabrication processing, can have anisotropic and/or functionally graded properties that notably include aligned and graded porosity. Freeze tape casting was developed to enable optimization of the microstructures of porous ceramic components for use as solid oxide electrodes in fuel cells: Through alignment and grading of pores, one can tailor surface areas and diffusion channels for flows of gas and liquid species involved in fuel-cell reactions. Freeze tape casting offers similar benefits for fabrication of optimally porous ceramics for use as catalysts, gas sensors, and filters.

Method of preparing thin porous sheets of ceramic material

DOEpatents

Swarr, T.E.; Nickols, R.C.; Krasij, M.

1984-05-23

A method of forming thin porous sheets of ceramic material for use as electrodes or other components in a molten carbonate fuel cell is disclosed. The method involves spray drying a slurry of fine ceramic particles in liquid carrier to produce generally spherical agglomerates of high porosity and a rough surface texture. The ceramic particles may include the electrode catalyst and the agglomerates can be calcined to improve mechanical strength. After slurrying with suitable volatile material and binder tape casting is used to form sheets that are sufficiently strong for further processing and handling in the assembly of a high temperature fuel cell.

Ceramics in Restorative and Prosthetic DENTISTRY1

NASA Astrophysics Data System (ADS)

Kelly, J. Robert

1997-08-01

This review is intended to provide the ceramic engineer with information about the history and current use of ceramics in dentistry, contemporary research topics, and potential research agenda. Background material includes intra-oral design considerations, descriptions of ceramic dental components, and the origin, composition, and microstructure of current dental ceramics. Attention is paid to efforts involving net-shape processing, machining as a forming method, and the analysis of clinical failure. A rationale is presented for the further development of all-ceramic restorative systems. Current research topics receiving attention include microstructure/processing/property relationships, clinical failure mechanisms and in vitro testing, wear damage and wear testing, surface treatments, and microstructural modifications. The status of the field is critically reviewed with an eye toward future work. Significant improvements seem possible in the clinical use of ceramics based on engineering solutions derived from the study of clinically failed restorations, on the incorporation of higher levels of "biomimicry" in new systems, and on the synergistic developments in dental cements and adhesive dentin bonding.

Robust Joining and Assembly Technologies for Ceramic Matrix Composites: Technical Challenges and Opportunities

NASA Technical Reports Server (NTRS)

Mrityunjay, Singh; Gray, Hugh R. (Technical Monitor)

2002-01-01

Fiber reinforced ceramic matrix composites are under active consideration for use in a wide variety of high temperature applications within the aeronautics, energy, process, and nuclear industries. The engineering designs require fabrication and manufacturing of complex shaped parts. In many instances, it is more economical to build up complex shapes by Joining simple geometrical shapes. Thus, joining and attachment have been recognized as enabling technologies for successful utilization of ceramic components in various demanding applications. In this presentation, various challenges and opportunities in design, fabrication, and testing of high temperature joints in ceramic matrix composites will be presented. Various joint design philosophies and design issues in joining of composites will be discussed along with an affordable, robust ceramic joining technology (ARCJoinT). A wide variety of ceramic composites, in different shapes and sizes, have been joined using this technology. Microstructure and mechanical properties of joints will be reported. Current status of various ceramic joining technologies and future prospects for their applications will also be discussed.

Strain isolated ceramic coatings

NASA Technical Reports Server (NTRS)

Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

1985-01-01

Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

Braze material for joining ceramic to metal and ceramic to ceramic surfaces and joined ceramic to metal and ceramic to ceramic article

DOEpatents

Hunt, T.K.; Novak, R.F.

1991-05-07

An improved active metal braze filler material is provided in which the coefficient of thermal expansion of the braze filler is more closely matched with that of the ceramic and metal, or two ceramics, to provide ceramic to metal, or ceramic to ceramic, sealed joints and articles which can withstand both high temperatures and repeated thermal cycling without failing. The braze filler material comprises a mixture of a material, preferably in the form of a powder, selected from the group consisting of molybdenum, tungsten, silicon carbide and mixtures thereof, and an active metal filler material selected from the group consisting of alloys or mixtures of nickel and titanium, alloys or mixtures of nickel and zirconium, alloys or mixtures of nickel, titanium, and copper, alloys or mixtures of nickel, titanium, and zirconium, alloys or mixtures of niobium and nickel, alloys or mixtures of niobium and zirconium, alloys or mixtures of niobium and titanium, alloys or mixtures of niobium, titanium, and nickel, alloys or mixtures of niobium, zirconium, and nickel, and alloys or mixtures of niobium, titanium, zirconium, and nickel. The powder component is selected such that its coefficient of thermal expansion will effect the overall coefficient of thermal expansion of the braze material so that it more closely matches the coefficients of thermal expansion of the ceramic and metal parts to be joined. 3 figures.

Braze material for joining ceramic to metal and ceramic to ceramic surfaces and joined ceramic to metal and ceramic to ceramic article

DOEpatents

Hunt, Thomas K.; Novak, Robert F.

1991-01-01

An improved active metal braze filler material is provided in which the coefficient of thermal expansion of the braze filler is more closely matched with that of the ceramic and metal, or two ceramics, to provide ceramic to metal, or ceramic to ceramic, sealed joints and articles which can withstand both high temperatures and repeated thermal cycling without failing. The braze filler material comprises a mixture of a material, preferably in the form of a powder, selected from the group consisting of molybdenum, tungsten, silicon carbide and mixtures thereof, and an active metal filler material selected from the group consisting of alloys or mixtures of nickel and titanium, alloys or mixtures of nickel and zirconium, alloys or mixtures of nickel, titanium, and copper, alloys or mixtures of nickel, titanium, and zirconium, alloys or mixtures of niobium and nickel, alloys or mixtures of niobium and zirconium, alloys or mixtures of niobium and titanium, alloys or mixtures of niobium, titanium, and nickel, alloys or mixtures of niobium, zirconium, and nickel, and alloys or mixtures of niobium, titanium, zirconium, and nickel. The powder component is selected such that its coefficient of thermal expansion will effect the overall coefficient of thermal expansion of the braze material so that it more closely matches the coefficients of thermal expansion of the ceramic and metal parts to be joined.

The characterization of ceramic alumina prepared by using additive glass beads

NASA Astrophysics Data System (ADS)

Suprapedi; Muljadi; Sardjono, Priyo

2018-01-01

The ceramic alumina has been made by using additive glass bead (5 and 10 % wt.). There are two kinds of materials, such as : gamma Alumina and glass bead. Synthesis of alumina was done by ball milling for 24 hours, then the mixed powder was dried in drying oven at 100 °C for 6 hours. Furthermore, the dried powder was mixed by using 2 % of PVA and continued with compacted to form a pellet with pressure of 50 MPA. The next step is sintering process with variation temperature of 1150, 1200, 1250, 1300 and 1400 °C and holding time for 2 hours. The characterization conducted are consist of test density, hardness, shrinkage, and microstructure. The results show that ceramic alumina with addition of 10 % wt. glass bead has the higher value of density, hardness and shrinkage than addition of 5% wt. glass bead. The highest characterization of ceramic alumina with addition 10 % glass bead was achieved at sintering temperature of 1400 °C with density 3.68 g/cm3, hardness vickers 780.40 Hv and shrinkage 15.23 %. The XRD results show that it was founds a corrundum (alpha Alumina) as dominant phase and mullite as minor phase.

High-Temperature Insulating Gap Filler

NASA Technical Reports Server (NTRS)

Toombs, Gordon R.; Oyoung, Kevin K.; Stevens, Everett G.

1991-01-01

New inorganic, ceramic filler for gaps between refractory ceramic tiles offers high resistance to heat and erosion. Consists of ceramic-fiber fabric precoated with silica and further coated with silica containing small amount of silicon carbide powder to increase thermal emittance. Developed as replacement for organic filler used on thermal-protection system of Space Shuttle. Promises to serve for many missions and to reduce cost and delay of refurbishing aerospace craft. Used as sealing material in furnaces or as heat shield for sensitive components in automobiles, aircraft, and home appliances.

Physics and Technology of Transparent Ceramic Armor: Sintered Al2O3 vs Cubic Materials

DTIC Science & Technology

2006-08-01

4,841,195, June 20, 1989. [20] N. Saito, Sh.-I. Matsuda, T . Ikegami , "Fabrication of transparent yttria ceramics at low temperature using...Hutzler, T .; Klimke, J. (2005) Physics and Technology of Transparent Ceramic Armor: Sintered Al2O3 vs Cubic Materials. In Nanomaterials Technology...a greater loss of transmission. Or vice versa: all components with a real in-line transmission T < Tth suffer a loss (Tth - T ), and this loss

Method and product for phosphosilicate slurry for use in dentistry and related bone cements

DOEpatents

Wagh, Arun S.; Primus, Carolyn

2006-08-01

The present invention is directed to magnesium phosphate ceramics and their methods of manufacture. The composition of the invention is produced by combining a mixture of a substantially dry powder component with a liquid component. The substantially dry powder component comprises a sparsely soluble oxide powder, an alkali metal phosphate powder, a sparsely soluble silicate powder, with the balance of the substantially dry powder component comprising at least one powder selected from the group consisting of bioactive powders, biocompatible powders, fluorescent powders, fluoride releasing powders, and radiopaque powders. The liquid component comprises a pH modifying agent, a monovalent alkali metal phosphate in aqueous solution, the balance of the liquid component being water. The use of calcined magnesium oxide as the oxide powder and hydroxylapatite as the bioactive powder produces a self-setting ceramic that is particularly suited for use in dental and orthopedic applications.

Nuclear Magnetic Resonance Used to Quantify the Effect of Pyrolysis Conditions on the Oxidative Stability of Silicon Oxycarbide Ceramics

NASA Technical Reports Server (NTRS)

1996-01-01

This work was undertaken in support of the Low Cost Ceramic Composite Virtual Company, (LC^3), whose members include Northrop Grumman Corporation, AlliedSignal Inc., and Allison Advanced Development Company. LC^3 is a cost-shared effort funded by the Advanced Research Projects Agency (ARPA) and the LC^3 participants to develop a low-cost fabrication methodology for manufacturing ceramic matrix composite structural components. The program, which is being administered by the U.S. Air Force Wright Laboratory Materials Directorate, is focused on demonstrating a ceramic matrix composite turbine seal for a regional aircraft engine. This part is to be fabricated by resin transfer molding of a siloxane polymer into a fiber preform that will be transformed into a ceramic by pyrolytic conversion.

Effects of poling over the orthorhombic-tetragonal phase transition temperature in compositionally homogeneous (K,Na)NbO3-based ceramics

NASA Astrophysics Data System (ADS)

Morozov, M. I.; Kungl, H.; Hoffmann, M. J.

2011-03-01

Li-, Ta-, and Mn-modified (K,Na)NbO3 ceramics with various compositional homogeneity have been prepared by conventional and precursor methods. The homogeneous ceramic has demonstrated a sharper peak in temperature dependent piezoelectric response. The dielectric and piezoelectric properties of the homogeneous ceramics have been characterized at the experimental subcoercive electric fields near the temperature of the orthorhombic-tetragonal phase transition with respect to poling in both phases. Poling in the tetragonal phase is shown to enhance the low-signal dielectric and piezoelectric properties in the orthorhombic phase.

Investigation of the Kinetic Energy Characterization of Advanced Ceramics

DTIC Science & Technology

2015-04-01

of Science, under a US Army International Technology Center contract. These ceramic formulations were compared with standard armor-grade boron ...Experimental Methodology 1 3. Results and Discussion 4 3.1 Aluminum Performance Baseline 4 3.2 Ceramic Inspection 6 3.3 Boron Carbide 6 3.4 Silicon...Carbide 7 3.5 Boron Carbide–Aluminum Nitride 7 3.6 Boron Carbide–Vanadium Diboride 7 3.7 Titanium Nitride–Aluminum Nitride 8 3.8 Comparative

A ceramic microreactor for the synthesis of water soluble CdS and CdS/ZnS nanocrystals with on-line optical characterization

NASA Astrophysics Data System (ADS)

Pedro, Sara Gómez-De; Puyol, Mar; Izquierdo, David; Salinas, Iñigo; de La Fuente, J. M.; Alonso-Chamarro, Julián

2012-02-01

In this paper, a computer controlled microreactor to synthesize water soluble CdS and CdS/ZnS nanocrystals with in situ monitoring of the reaction progress is developed. It is based on ceramic tapes and the Low-Temperature Co-fired Ceramics technology (LTCC). As well the microsystem set-up, the microreactor fluidic design has also been thoroughly optimized. The final device is based on a hydrodynamic focusing of the reagents followed by a three-dimensional micromixer. This generates monodispersed and stable CdS and core-shell CdS/ZnS nanocrystals of 4.5 and 4.2 nm, respectively, with reproducible optical properties in terms of fluorescence emission wavelengths, bandwidth, and quantum yields, which is a key requirement for their future analytical applications. The synthetic process is also controlled in real time with the integration of an optical detection system for absorbance and fluorescence measurements based on commercial miniaturized optical components. This makes possible the efficient managing of the hydrodynamic variables to obtain the desired colloidal suspension. As a result, a simple, economic, robust and portable microsystem for the well controlled synthesis of CdS and CdS/ZnS nanocrystals is presented. Moreover, the reaction takes place in aqueous medium, thus allowing the direct modular integration of this microreactor in specific analytical microsystems, which require the use of such quantum dots as labels.

Development of processing techniques for advanced thermal protection materials

NASA Technical Reports Server (NTRS)

Selvaduray, Guna S.

1995-01-01

The main purpose of this work has been in the development and characterization of materials for high temperature applications. Thermal Protection Systems (TPS) are constantly being tested, and evaluated for increased thermal shock resistance, high temperature dimensional stability, and tolerance to environmental effects. Materials development was carried out through the use of many different instruments and methods, ranging from extensive elemental analysis to physical attributes testing. The six main focus areas include: (1) protective coatings for carbon/carbon composites; (2) TPS material characterization; (3) improved waterproofing for TPS; (4) modified ceramic insulation for bone implants; (5) improved durability ceramic insulation blankets; and (6) ultra-high temperature ceramics. This report describes the progress made in these research areas during this contract period.

Laser-gyro materials studies

NASA Astrophysics Data System (ADS)

Covino, J.; Bennett, J. M.

1986-03-01

Material properties of low-expansion glass and glass-ceramic materials have been measured. The materials that have been characterized are ultralow-expansion (ULE) type 7971 quartz, a new glass-ceramic material RLA 559,122 from Corning Glass Works, fused quartz from General Electric, Zerodur from Schott Glaswerke, and Cervit C-101 from Owens-Illinois. Characterization has included measurements of X-ray powder diffraction patterns, some elemental analyses, helium permeability, thermal expansion, particle-size distributions, optical properties, and optical finish studies.

Microstructure characterization and SCG of newly engineered dental ceramics.

PubMed

Ramos, Nathália de Carvalho; Campos, Tiago Moreira Bastos; Paz, Igor Siqueira de La; Machado, João Paulo Barros; Bottino, Marco Antonio; Cesar, Paulo Francisco; Melo, Renata Marques de

2016-07-01

The aim of this study was to characterize the microstructure of four dental CAD-CAM ceramics and evaluate their susceptibility to stress corrosion. SEM and EDS were performed for microstructural characterization. For evaluation of the pattern of crystallization of the ceramics and the molecular composition, XRD and FTIR, respectively, were used. Elastic modulus, Poisson's ratio, density and fracture toughness were also measured. The specimens were subjected to biaxial flexure under five stress rates (0.006, 0.06, 0.6, 6 and 60MPa/s) to determine the subcritical crack growth parameters (n and D). Twenty-five specimens were further tested in mineral oil for determination of Weibull parameters. Two hundred forty ceramic discs (12mm diameter and 1.2mm thick) were made from four ceramics: feldspathic ceramic - FEL (Vita Mark II, Vita Zahnfabrik), ceramic-infiltrated polymer - PIC (Vita Enamic, Vita Zahnfabrik), lithium disilicate - LD (IPS e.max CAD, Ivoclar Vivadent) and zirconia-reinforced lithium silicate - LS (Vita Suprinity, Vita Zahnfabrik). PIC discs presented organic and inorganic phases (n=29.1±7.7) and Weibull modulus (m) of 8.96. The FEL discs showed n=36.6±6.8 and m=8.02. The LD discs showed a structure with needle-like disilicate grains in a glassy matrix and had the lowest value of n (8.4±0.8) and m=6.19. The ZLS discs showed similar rod-like grains, n=11.2±1.4 and m=9.98. The FEL and PIC discs showed the lowest susceptibility to slow crack growth (SCG), whereas the LD and ZLS discs presented the highest. PIC presented the lowest elastic modulus and no crystals in its composition, while ZLS presented tetragonal zirconia. The overall strength and SCG of the new materials did not benefit from the additional phase or microconstituents present in them. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Modular fabrication and characterization of complex silicon carbide composite structures Advanced Reactor Technologies (ART) Research Final Report (Feb 2015 – May 2017)

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

Khalifa, Hesham

Advanced ceramic materials exhibit properties that enable safety and fuel cycle efficiency improvements in advanced nuclear reactors. In order to fully exploit these desirable properties, new processing techniques are required to produce the complex geometries inherent to nuclear fuel assemblies and support structures. Through this project, the state of complex SiC-SiC composite fabrication for nuclear components has advanced significantly. New methods to produce complex SiC-SiC composite structures have been demonstrated in the form factors needed for in-core structural components in advanced high temperature nuclear reactors. Advanced characterization techniques have been employed to demonstrate that these complex SiC-SiC composite structures providemore » the strength, toughness and hermeticity required for service in harsh reactor conditions. The complex structures produced in this project represent a significant step forward in leveraging the excellent high temperature strength, resistance to neutron induced damage, and low neutron cross section of silicon carbide in nuclear applications.« less

A high temperature testing system for ceramic composites

NASA Technical Reports Server (NTRS)

Hemann, John

1994-01-01

Ceramic composites are presently being developed for high temperature use in heat engine and space power system applications. The operating temperature range is expected to be 1090 to 1650 C (2000 F to 3000 F). Very little material data is available at these temperatures and, therefore, it is desirable to thoroughly characterize the basic unidirectional fiber reinforced ceramic composite. This includes testing mainly for mechanical material properties at high temperatures. The proper conduct of such characterization tests requires the development of a tensile testing system includes unique gripping, heating, and strain measuring devices which require special considerations. The system also requires an optimized specimen shape. The purpose of this paper is to review various techniques for measuring displacements or strains, preferably at elevated temperatures. Due to current equipment limitations it is assumed that the specimen is to be tested at a temperature of 1430 C (2600F) in an oxidizing atmosphere. For the most part, previous high temperature material characterization tests, such as flexure and tensile tests, have been performed in inert atmospheres. Due to the harsh environment in which the ceramic specimen is to be tested, many conventional strain measuring techniques can not be applied. Initially a brief description of the more commonly used mechanical strain measuring techniques is given. Major advantages and disadvantages with their application to high temperature tensile testing of ceramic composites are discussed. Next, a general overview is given for various optical techniques. Advantages and disadvantages which are common to these techniques are noted. The optical methods for measuring strain or displacement are categorized into two sections. These include real-time techniques. Finally, an optical technique which offers optimum performance with the high temperature tensile testing of ceramic composites is recommended.

Study on Microstructures and Properties of Porous TiC Ceramics Fabricated by Powder Metallurgy

NASA Astrophysics Data System (ADS)

Ma, Yana; Bao, Chonggao; Han, Longhao; Chen, Jie

2017-02-01

Powder metallurgy process was used to fabricate porous titanium carbide (TiC) ceramics, in which TiC powders were taken as the raw materials, nickel was used as the metallic binder and urea was the space-holder. Microstructure, composition and phase of porous TiC ceramics were characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD). Flexure strength of the porous TiC ceramics was tested by a three-point bending method. The results show that macropores and micropores coexist in the prepared porous TiC ceramics. Moreover, the pore number, size and distribution in porous TiC ceramics can be controlled on demand. Particularly, the factors such as the number or size of space-holder, compacting pressure and Ni content have significant effect on the porosity and flexure strength.

Enhancement of fatigue endurance in ferroelectric PZT ceramic by the addition of bismuth layered SBT

NASA Astrophysics Data System (ADS)

Namsar, O.; Pojprapai, S.; Watcharapasorn, A.; Jiansirisomboon, S.

2014-10-01

Electrical fatigue properties of (1-x)PZT-xSBT ceramics (x = 0-1.0 weight fraction) were characterized. It was found that pure PZT ceramic had severe polarization fatigue. This was mainly attributed to an occurrence of the macroscopic cracks at near-electrode regions. On the contrary, pure SBT ceramic exhibited excellent fatigue resistance, which was attributed primarily to weak domain wall pinning. As small amount of SBT (0.1 ≤ x ≤ 0.3) was added into PZT, a small reduction of remanent polarization after fatigue process was observed. This demonstrated that these ceramics had high stability during the repeated domain switching due to their low oxygen vacancy concentration. Therefore, these results suggested that this new ceramic PZT-SBT system seemed to be an alternative material for replacing pure PZT in ferroelectric memory applications.

Thinning of PLZT ceramic wafers for sensor integration

NASA Astrophysics Data System (ADS)

Jin, Na; Liu, Weiguo

2010-08-01

Characteristics of transparent PLZT ceramics can be tailored by controlling the component of them, and therefore showed excellent dielectric, piezoelectric, pyroelectric and ferroelectric properties. To integrate the ceramics with microelectronic circuit to realize integrated applications, the ceramic wafers have to be thinned down to micrometer scale in thickness. A7/65/35 PLZT ceramic wafer was selected in this study for the thinning process. Size of the wafer was 10×10mm with an initial thickness of 300μm. A novel membrane transfer process (MTP) was developed for the thinning and integration of the ceramic wafers. In the MTP process, the ceramic wafer was bonded to silicon wafer using a polymer bonding method. Mechanical grinding method was applied to reduce the thickness of the ceramic. To minimize the surface damage in the ceramic wafer caused by the mechanical grinding, magnetorheological finishing (MRF) method was utilized to polish the wafer. White light interference (WLI) apparatus was used to monitor the surface qualities of the grinded and ploished ceramic wafers. For the PLZT membrane obtained from the MTP process, the final thickness of the thinned and polished wafer was 10μm, the surface roughness was below 1nm in rms, and the flatness was better than λ/5.

Thin Film Sensors for Surface Measurements

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Wrbanek, John D.; Fralick, Gustave C.

2001-01-01

Advanced thin film sensors that can provide accurate surface temperature, strain, and heat flux measurements have been developed at NASA Glenn Research Center. These sensors provide minimally intrusive characterization of advanced propulsion materials and components in hostile, high-temperature environments as well as validation of propulsion system design codes. The sensors are designed for applications on different material systems and engine components for testing in engine simulation facilities. Thin film thermocouples and strain gauges for the measurement of surface temperature and strain have been demonstrated on metals, ceramics and advanced ceramic-based composites of various component configurations. Test environments have included both air-breathing and space propulsion-based engine and burner rig environments at surface temperatures up to 1100 C and under high gas flow and pressure conditions. The technologies developed for these sensors as well as for a thin film heat flux gauge have been integrated into a single multifunctional gauge for the simultaneous real-time measurement of surface temperature, strain, and heat flux. This is the first step toward the development of smart sensors with integrated signal conditioning and high temperature electronics that would have the capability to provide feedback to the operating system in real-time. A description of the fabrication process for the thin film sensors and multifunctional gauge will be provided. In addition, the material systems on which the sensors have been demonstrated, the test facilities and the results of the tests to-date will be described. Finally, the results will be provided of the current effort to demonstrate the capabilities of the multifunctional gauge.

Plugging micro-leaks in multi-component, ceramic tubesheets with material leached therefrom

DOEpatents

Bieler, B.H.; Tsang, F.Y.

1985-03-19

Cracks, in ceramic wall members, on the order of 1 micron or less in width are plugged helium-tight by selectively leaching a component of the wall member with a solvent, letting the resultant leach form a liquid bridge within the crack, removing the solvent and sintering the resultant residue. This method is of particular value for remedying microcracks or channels in a cell member constituting a tubesheet in a hollow fiber type, high temperature battery cell, such as a sodium/sulfur cell, for example. 1 fig.

A comparison of forming technologies for ceramic gas-turbine engine components

NASA Technical Reports Server (NTRS)

Hengst, R. R.; Heichel, D. N.; Holowczak, J. E.; Taglialavore, A. P.; Mcentire, B. J.

1990-01-01

For over ten years, injection molding and slip casting have been actively developed as forming techniques for ceramic gas turbine components. Co-development of these two processes has continued within the U.S. DOE-sponsored Advanced Turbine Technology Application Project (ATTAP). Progress within ATTAP with respect to these two techniques is summarized. A critique and comparison of the two processes are given. Critical aspects of both processes with respect to size, dimensional control, material properties, quality, cost, and potential for manufacturing scale-up are discussed.

Plugging micro-leaks in multi-component, ceramic tubesheets with material leached therefrom

DOEpatents

Bieler, Barrie H.; Tsang, Floris Y.

1985-03-19

Cracks, in ceramic wall members, on the order of 1 micron or less in width are plugged helium-tight by selectively leaching a component of the wall member with a solvent, letting the resultant leach form a liquid bridge within the crack, removing the solvent and sintering the resultant residue. This method is of particular value for remedying microcracks or channels in a cell member constituting a tubesheet in a hollow fiber type, high temperature battery cell, such as a sodium/sulfur cell, for example.

Environmental Stability and Oxidation Behavior of HfO2-Si and YbGd(O) Based Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Farmer, Serene; McCue, Terry R.; Harder, Bryan; Hurst, Janet B.

2017-01-01

Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, environmental durable environmental barrier coating systems. In this paper, the durability and performance of advanced Electron Beam-Physical Vapor Deposition (EB-PVD) NASA HfO2-Si and YbGdSi(O) EBC bond coat top coat systems for SiCSiC CMC have been summarized. The high temperature thermomechanical creep, fatigue and oxidation resistance have been investigated in the laboratory simulated high-heat-flux environmental test conditions. The advanced NASA EBC systems showed promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Strength and fatigue of NT551 silicon nitride and NT551 diesel exhaust valves

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

Andrews, M.J.; Werezczak, A.A.; Kirkland, T.P.

2000-02-01

The content of this report is excerpted from Mark Andrew's Ph.D. Thesis (Andrews, 1999), which was funded by a DOE/OTT High Temperature Materials Laboratory Graduate Fellowship. It involves the characterization of NT551 and valves fabricated with it. The motivations behind using silicon nitride (Si{sub 3}N{sub 4}) as an exhaust valve for a diesel engine are presented in this section. There are several economic factors that have encouraged the design and implementation of ceramic components for internal combustion (IC) engines. The reasons for selecting the diesel engine valve for this are also presented.

A Novel Technique for the Connection of Ceramic and Titanium Implant Components Using Glass Solder Bonding

PubMed Central

Mick, Enrico; Tinschert, Joachim; Mitrovic, Aurica; Bader, Rainer

2015-01-01

Both titanium and ceramic materials provide specific advantages in dental implant technology. However, some problems, like hypersensitivity reactions, corrosion and mechanical failure, have been reported. Therefore, the combining of both materials to take advantage of their pros, while eliminating their respective cons, would be desirable. Hence, we introduced a new technique to bond titanium and ceramic materials by means of a silica-based glass ceramic solder. Cylindrical compound samples (Ø10 mm × 56 mm) made of alumina toughened zirconia (ATZ), as well as titanium grade 5, were bonded by glass solder on their end faces. As a control, a two-component adhesive glue was utilized. The samples were investigated without further treatment, after 30 and 90 days of storage in distilled water at room temperature, and after aging. All samples were subjected to quasi-static four-point-bending tests. We found that the glass solder bonding provided significantly higher bending strength than adhesive glue bonding. In contrast to the glued samples, the bending strength of the soldered samples remained unaltered by the storage and aging treatments. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analyses confirmed the presence of a stable solder-ceramic interface. Therefore, the glass solder technique represents a promising method for optimizing dental and orthopedic implant bondings. PMID:28793440

NASA Glenn Research Center UEET (Ultra-Efficient Engine Technology) Program: Agenda and Abstracts

NASA Technical Reports Server (NTRS)

Manthey, Lri

2001-01-01

Topics discussed include: UEET Overview; Technology Benefits; Emissions Overview; P&W Low Emissions Combustor Development; GE Low Emissions Combustor Development; Rolls-Royce Low Emissions Combustor Development; Honeywell Low Emissions Combustor Development; NASA Multipoint LDI Development; Stanford Activities In Concepts for Advanced Gas Turbine Combustors; Large Eddy Simulation (LES) of Gas Turbine Combustion; NASA National Combustion Code Simulations; Materials Overview; Thermal Barrier Coatings for Airfoil Applications; Disk Alloy Development; Turbine Blade Alloy; Ceramic Matrix Composite (CMC) Materials Development; Ceramic Matrix Composite (CMC) Materials Characterization; Environmental Barrier Coatings (EBC) for Ceramic Matrix Composite (CMC) Materials; Ceramic Matrix Composite Vane Rig Testing and Design; Ultra-High Temperature Ceramic (UHTC) Development; Lightweight Structures; NPARC Alliance; Technology Transfer and Commercialization; and Turbomachinery Overview; etc.

Ytterbium-doped glass-ceramics for optical refrigeration.

PubMed

Filho, Elton Soares de Lima; Krishnaiah, Kummara Venkata; Ledemi, Yannick; Yu, Ye-Jin; Messaddeq, Younes; Nemova, Galina; Kashyap, Raman

2015-02-23

We report for the first time the characterization of glass-ceramics for optical refrigeration. Ytterbium-doped nanocrystallites were grown in an oxyfluoride glass matrix of composition 2YbF(3):30SiO(2)-15Al(2)O(3)-25CdF(2)-22PbF(2)-4YF(3), forming bulk glass-ceramics at three different crystalisation levels. The samples are compared with a corresponding uncrystalised (glass) sample, as well as a Yb:YAG sample which has presented optical cooling. The measured X-ray diffraction spectra, and thermal capacities of the samples are reported. We also report for the first time the use of Yb:YAG as a reference for absolute photometric quantum efficiency measurement, and use the same setup to characterize the glass and glass-ceramic samples. The cooling figure-of-merit was measured by optical calorimetry using a fiber Bragg grating and found to depend on the level of crystallization of the sample, and that samples with nanocrystallites result in higher quantum efficiency and lower background absorption than the pure-glass sample. In addition to laser-induced cooling, the glass-ceramics have the potential to serve as a reference for quantum efficiency measurements.

Characterization of a wollastonite glass-ceramic material prepared using sugar cane bagasse ash (SCBA) as one of the raw materials

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

Teixeira, Silvio R., E-mail: rainho@fct.unesp.br; Souza, Agda E.; Carvalho, Claudio L.

Glass-ceramic material prepared with sugar cane bagasse ash as one of the raw materials was characterized to determine some important properties for its application as a coating material. X-ray diffraction patterns showed that wollastonite-2M (CaSiO{sub 3}) was the major glass-ceramic phase. The Rietveld method was used to quantify the crystalline (60 wt.%) and vitreous (40 wt.%) phases in the glass-ceramic. The microstructure (determined by scanning electron microscopy) of this material had a marble appearance, showing a microporous network of elongated crystals with some areas with dendritic, feather-like ordering. Microhardness data gave a mean hardness value of 564.4 HV (Vickers-hardness), andmore » light microscopy disclosed a greenish brown colored material with a vitreous luster. - Highlights: • We studied the properties of a glass-ceramic material obtained from sugarcane ash. • This material has the appearance and hardness of natural stones. • A refining method gave information about its amorphous and crystalline phases. • This material has potential to be used as coating plates for buildings.« less

[Wear behavior of enamel and veneering ceramics].

PubMed

Gao, Qing-ping; Chao, Yong-lie; Jian, Xin-chun; Guo, Feng; Meng, Yu-kun

2007-10-01

To compare the wear between the enamel and two types of dental decoration porcelains for all-ceramic restorations (Vita-alpha, Vintage AL). Friction coefficients, wear scar width, element concentrations and wear surface evolution were considered relatively to the tribology of that in vivo situation. The wear scars of the samples were characterized by means of dynamic atomic force microscopy (DFM). The different element concentrations of the surface before/after the wear test were determined with energy dispersion spectrometry (EDS). The friction coefficient varied from time in each kind of material. The statistical differences between materials were observed in wear scar width and properties of materials (P<0.05). DFM results showed wear surface of natural tooth full of abrasive particles and denaturation of dental texture. Wear surface of veneering ceramics consisted mainly of abrasive particles, plough and microcracking. EDS results showed that the element concentration of Fe was obviously found on the samples after wear. The main underlying mechanisms of natural teeth wear are abrasive, and denaturation of dental texture. Abrasive wear, adhesion and fatigue of veneering ceramics characterize the wear patterns which plays different role in Vita-alpha and Vintage AL. The wear patterns of veneering ceramics can be described as mild wear.

Multidisciplinary Approach for Restoring Function and Esthetics in a Patient with Amelogenesis Imperfecta: A Clinical Report

PubMed Central

Kamble, Vaibhav D; Parkhedkar, Rambhau D

2013-01-01

Amelogenesis Imperfecta (AI) is a genetically determined and enamel mineralization defect reported, depicted as “Hereditary brown teeth.” AI is characterized as a clinical entity and its clinical manifestations, histological appearance, and genetic pattern are characterized by their heterogeneity. The need for prosthodontic management of this group of patients varies. Some patients need oral hygiene instructions only, whereas others need extensive dental treatment that includes composite restorations, metal ceramic crowns, all ceramic crowns, porcelain veneers. A 20-year-old male patient presented with sensitive, discoloured, and mutilated teeth, with a decreased vertical dimension of occlusion. The 4-year recall examination revealed no pathology associated with the full mouth rehabilitation, and the patient’s aesthetic and functional expectations were satisfied. The rehabilitation included all-ceramic crowns on anterior teeth and metal-ceramic crowns on posterior teeth following endodontic treatment and a crown-lengthening procedure for eliminating tooth sensitivity, improving the aesthetics and occlusion, and for restoring function. PMID:24551735

Synthesis and characterization of a BaGdF5:Tb glass ceramic as a nanocomposite scintillator for x-ray imaging.

PubMed

Lee, Gyuhyon; Struebing, Christian; Wagner, Brent; Summers, Christopher; Ding, Yong; Bryant, Alex; Thadhani, Naresh; Shedlock, Daniel; Star-Lack, Josh; Kang, Zhitao

2016-05-20

Transparent glass ceramics with embedded light-emitting nanocrystals show great potential as low-cost nanocomposite scintillators in comparison to single crystal and transparent ceramic scintillators. In this study, cubic structure BaGdF5:Tb nanocrystals embedded in an aluminosilicate glass matrix are reported for potential high performance MeV imaging applications. Scintillator samples with systematically varied compositions were prepared by a simple conventional melt-quenching method followed by annealing. Optical, structural and scintillation properties were characterized to guide the design and optimization of selected material systems, aiming at the development of a system with higher crystal volume and larger crystal size for improved luminosity. It is observed that enhanced scintillation performance was achieved by tuning the glass matrix composition and using GdF3 in the raw materials, which served as a nucleation agent. A 26% improvement in light output was observed from a BaGdF5:Tb glass ceramic with addition of GdF3.

CARES/Life Ceramics Durability Evaluation Software Used for Mars Microprobe Aeroshell

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.

1998-01-01

The CARES/Life computer program, which was developed at the NASA Lewis Research Center, predicts the probability of a monolithic ceramic component's failure as a function of time in service. The program has many features and options for materials evaluation and component design. It couples commercial finite element programs-which resolve a component's temperature and stress distribution-to-reliability evaluation and fracture mechanics routines for modeling strength-limiting defects. These routines are based on calculations of the probabilistic nature of the brittle material's strength. The capability, flexibility, and uniqueness of CARES/Life has attracted many users representing a broad range of interests and has resulted in numerous awards for technological achievements and technology transfer.

Process for fabrication of cermets

DOEpatents

Landingham, Richard L [Livermore, CA

2011-02-01

Cermet comprising ceramic and metal components and a molten metal infiltration method and process for fabrication thereof. The light weight cermets having improved porosity, strength, durability, toughness, elasticity fabricated from presintered ceramic powder infiltrated with a molten metal or metal alloy. Alumina titanium cermets biocompatible with the human body suitable for bone and joint replacements.

Thermal Response Of Composite Insulation

NASA Technical Reports Server (NTRS)

Stewart, David A.; Leiser, Daniel B.; Smith, Marnell; Kolodziej, Paul

1988-01-01

Engineering model gives useful predictions. Pair of reports presents theoretical and experimental analyses of thermal responses of multiple-component, lightweight, porous, ceramic insulators. Particular materials examined destined for use in Space Shuttle thermal protection system, test methods and heat-transfer theory useful to chemical, metallurgical, and ceramic engineers needing to calculate transient thermal responses of refractory composites.

Current Status of Hybrid Bearing Damage Detection

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Certo, Joseph M.; Morales, Wilfredo

2004-01-01

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high pressure oxidizer turbopump, on the space shuttle main engine, led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si3N4 balls. The aerospace industry is currently studying the use of hybrid bearings and naturally the failure modes of these bearings become an issue in light of the limited data available. In today s turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Since the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure. The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris, in oil, using a commercial particle counter.

Experimentally validated computational modeling of organic binder burnout from green ceramic compacts

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

Ewsuk, K.G.; Cochran, R.J.; Blackwell, B.F.

The properties and performance of a ceramic component is determined by a combination of the materials from which it was fabricated and how it was processed. Most ceramic components are manufactured by dry pressing a powder/binder system in which the organic binder provides formability and green compact strength. A key step in this manufacturing process is the removal of the binder from the powder compact after pressing. The organic binder is typically removed by a thermal decomposition process in which heating rate, temperature, and time are the key process parameters. Empirical approaches are generally used to design the burnout time-temperaturemore » cycle, often resulting in excessive processing times and energy usage, and higher overall manufacturing costs. Ideally, binder burnout should be completed as quickly as possible without damaging the compact, while using a minimum of energy. Process and computational modeling offer one means to achieve this end. The objective of this study is to develop an experimentally validated computer model that can be used to better understand, control, and optimize binder burnout from green ceramic compacts.« less

Hard ceramic coatings: an experimental study on a novel damping treatment

NASA Astrophysics Data System (ADS)

Patsias, Sophoclis; Tassini, Nicola; Stanway, Roger

2004-07-01

This paper describes a novel damping treatment, namely hard ceramic coatings. These materials can be applied on almost any surface (internal or external) of a component. Their effect is the significant reduction of vibration levels and hence the extension of life expectancy of the component. The damping features of air-plasma-sprayed ceramic coatings (for example amplitude dependence, influence of initial amplitude) are discussed and the experimental procedure employed for testing and characterising such materials is also described. This test procedure is based around a custom-developed rig that allows one to measure the damping (internal friction) of specimens at controlled frequencies, strain amplitudes and, if required, various temperatures. A commonly used Thermal Barrier Coating, Yttria Stabilised Zirconia (8%), is used to demonstrate the above mentioned features. The damping effectiveness of this coating is then compared against two established damping treatments: polymer Free Layer Damping (FLD) and Constrained Layer Damping (CLD). The paper discusses the major issues in characterising ceramic damping coatings and their damping effectiveness when compared against the "traditional" approaches. Finally, the paper concludes with suggestions for further research.

Porous ceramic membrane with superhydrophobic and superoleophilic surface for reclaiming oil from oily water

NASA Astrophysics Data System (ADS)

Su, Changhong; Xu, Youqian; Zhang, Wei; Liu, Yang; Li, Jun

2012-01-01

A porous ceramic tube with superhydrophobic and superoleophilic surface was fabricated by sol-gel and then surface modification with polyurethane-polydimethysiloxane, and an oil-water separator based on the porous ceramic tube was erected to characterize superhydrophobic and superoleophilic surface's separation efficiency and velocity when being used to reclaim oil from oily water and complex oily water containing clay particle. The separator is fit for reclaiming oil from oily water.

Synthesis and surface characterization of alumina-silica-zirconia nanocomposite ceramic fibres on aluminium at room temperature

NASA Astrophysics Data System (ADS)

Mubarak Ali, M.; Raj, V.

2010-04-01

Alumina-silica-zirconia nanocomposite (ASZNC) ceramic fibres were synthesized by conventional anodization route. Scanning Electron Microscopy (SEM), Atomic Force microscopy (AFM), X-Ray Diffraction (XRD) and Energy Dispersive X-Ray spectroscopy (EDAX) were used to characterize the morphology and crystalloid structure of ASZNC fibres. Current density (DC) is one of the important parameters to get the alumina-silica-zirconia nanocomposite (ASZNC) ceramic fibres by this route. Annealing of the films exhibited a drastic change in the properties due to improved crystallinity. The root mean square roughness of the sample observed from atomic force microscopic analysis is about 71.5 nm which is comparable to the average grain size of the coatings which is about 72 nm obtained from X-Ray diffraction. The results indicate that, the ASZNC fibres are arranged well in the nanostructure. The thickness of the coating increased with the anodizing time, but the coatings turned rougher and more porous. At the initial stage the growth of ceramic coating increases inwards to the metal substrate and outwards to the coating surface simultaneously. Subsequently, it mainly grows towards the metal substrate and the density of the ceramic coating increases gradually, which results in the decrease of the total thickness as anodizing time increases. This new approach of preparing ASZNC ceramic fibres may be important in applications ranging from gas sensors to various engineering materials.

Ceramic bearings for use in gas turbine engines

NASA Technical Reports Server (NTRS)

Zaretsky, Erwin V.

1988-01-01

Three decades of research by U.S. industry and government laboratories have produced a vast body of data related to the use of ceramic rolling element bearings and bearing components for aircraft gas turbine engines. Materials such as alumina, silicon carbide, titanium carbide, silicon nitride, and a crystallized glass ceramic have been investigated. Rolling-element endurance tests and analysis of full-complement bearings have been performed. Materials and bearing design methods have continuously improved over the years. This paper reviews a wide range of data and analyses with emphasis on how early NASA contributions as well as more recent data can enable the engineer or metallurgist to determine just where ceramic bearings are most applicable for gas turbines.

Development of Thin Film Ceramic Thermocouples for High Temperature Environments

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Farmer, Serene C.; Sayir, Ali; Blaha, Charles A.; Gonzalez, Jose M.

2004-01-01

The maximum use temperature of noble metal thin film thermocouples of 1100 C (2000 F) may not be adequate for use on components in the increasingly harsh conditions of advanced aircraft and next generation launch technology. Ceramic-based thermocouples are known for their high stability and robustness at temperatures exceeding 1500 C, but are typically found in the form of rods or probes. NASA Glenn Research Center is investigating the feasibility of ceramics as thin film thermocouples for extremely high temperature applications to take advantage of the stability and robustness of ceramics and the non-intrusiveness of thin films. This paper will discuss the current state of development in this effort.

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1991-01-01

This report summarizes work performed in support of the development and demonstration of a structural ceramic technology for automotive gas turbine engines. The AGT101 regenerated gas turbine engine developed under the previous DOE/NASA Advanced Gas Turbine (AGT) program is being utilized for verification testing of the durability of next-generation ceramic components and their suitability for service at reference powertrain design conditions. Topics covered in this report include ceramic processing definition and refinement, design improvements to the test bed engine and test rigs, and design methodologies related to ceramic impact and fracture mechanisms. Appendices include reports by ATTAP subcontractors addressing the development of silicon nitride and silicon carbide families of materials and processes.

Gamma radiation in ceramic capacitors: a study for space missions

NASA Astrophysics Data System (ADS)

dos Santos Ferreira, Eduardo; Sarango Souza, Juliana

2017-10-01

We studied the real time effects of the gamma radiation in ceramic capacitors, in order to evaluate the effects of cosmic radiation on these devices. Space missions have electronic circuits with various types of devices, many studies have been done on semiconductor devices exposed to gamma radiation, but almost no studies for passive components, in particular ceramic capacitors. Commercially sold ceramic capacitors were exposed to gamma radiation, and the capacitance was measured before and after exposure. The results clearly show that the capacitance decreases with exposure to gamma radiation. We confirmed this observation in a real time capacitance measurement, obtained using a data logging system developed by us using the open source Arduino platform.

Effect of Opalescence(®) bleaching gels on the elution of bulk-fill composite components.

PubMed

Schuster, Lena; Reichl, Franz-Xaver; Rothmund, Lena; He, Xiuli; Yang, Yang; Van Landuyt, Kirsten L; Kehe, Kai; Polydorou, Olga; Hickel, Reinhard; Högg, Christof

2016-02-01

Bleaching treatments can affect release of components from conventional composites. In this continuing study the influence of two different bleaching gels on the elution of bulk-fill composite components was investigated. The composites Tetric EvoCeram(®) Bulk Fill, QuiXFil™ and X-tra fil were treated with the bleaching gels Opalescence PF 15% (PF 15%) for 5 h and PF 35% (PF 35%) for 30 min and then stored in methanol and water for 24 h and 7 d. The eluates were analyzed by gas chromatography/mass spectrometry (GC/MS). Unbleached specimens were used as control group. A total of 7 different elutable substances have been identified from the investigated composites after bleaching-treatment. Three of them were methacrylates: 2-hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA) and trimethylolpropane trimethacrylate (TMPTMA). Compared to the unbleached controls an increase in elution after PF 15%-treatment of following compounds was found: HEMA (Tetric EvoCeram(®) Bulk Fill), TEGDMA (QuiXFil™, X-tra fil) and 4-N,N-dimethylaminobenzoic acid butyl ethoxy ester (DMABEE) (Tetric EvoCeram(®) Bulk Fill, QuiXFil™, X-tra fil). Following compounds showed a reduction in elution after PF 35%-treatment compared to controls: TEGDMA (QuiXFil™) and DMABEE (Tetric EvoCeram(®) Bulk Fill). The highest concentration of HEMA was 0.22 mmol/l (Tetric EvoCeram(®) Bulk Fill, methanol, 7 d, PF 15%), the highest concentration of TEGDMA was 0.3 mmol/l (X-tra fil, water, 7 d, PF 15%) and the highest concentration of DMABEE was 0.05 mmol/l (QuiXFil™, water, 7 d, PF 35%). PF 15% and PF 35% can lead to reduced and/or increased elution of some bulk-fill components, compared to unbleached bulk-fill composites. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Biomechanical Assessment of Restored Mandibular Molar by Endocrown in Comparison to a Glass Fiber Post-Retained Conventional Crown: 3D Finite Element Analysis.

PubMed

Helal, Mohammed Abu; Wang, Zhigang

2017-10-25

To compare equivalent and contact stresses in a mandibular molar restored by all-ceramic crowns through two methods: ceramic endocrowns and ceramic crowns supported by fiber-reinforced composite (FRC) posts and core, by using 3D finite element analysis during normal masticatory load. Three 3D models of a mandibular first molar were made and labeled as such: intact molar with no restoration (A); ceramic endocrown-restored molar (B); ceramic crown supported by FRC posts and core restored molar (C). By using 3D FE analysis with contact components, normal masticatory load was simulated. The mvM stresses in all models were calculated. Maximal mvM stresses in the ceramic of restorations, dentin, and luting cement were contrasted among models and to values of materials' strength. Contact shear and tensile stresses in the restoration/tooth interface around restorations were also calculated. The highest mvM stress levels in the enamel and dentin for the tooth restored by ceramic endocrown were lower in the crown ceramic than in tooth restored with FRC posts and all-ceramic crowns; however, in the resin adhesive cement interface it was lower for ceramic crown supported by FRC posts than the in ceramic endocrown restoration. The maximum contact shear and tensile stress values along the restoration/tooth interface of ceramic endocrowns were lower than those with ceramic crowns supported by FRC posts. Ceramic endocrown restorations presented a lower mvM stress level in dentin than the conventional ceramic crowns supported by FRC posts and core. Ceramic endocrown restorations in molars are less susceptible to damage than those with conventional ceramic crowns retained by FRC posts. Ceramic endocrowns properly cemented in molars must not be fractured or loosen during normal masticatory load. Therefore, ceramic endocrowns are advised as practicable, minimally invasive, and esthetic restorations for root canal treated mandibular molars. © 2017 by the American College of Prosthodontists.

Characteristics of Ceramic Fiber Modified Asphalt Mortar

PubMed Central

Wan, Jiuming; Wu, Shaopeng; Xiao, Yue; Liu, Quantao; Schlangen, Erik

2016-01-01

Ceramic fiber, with a major composition of Al2O3 and SiO2, has advantages of stability at relatively high temperature, big specific surface area and resistance to external mechanical vibration. It has the potential contribution of improving the rutting resistance and temperature sensitivity of modified asphalt binder by proper modification design. In this research, ceramic fiber was introduced into both pen 60/80 and pen 80/100 asphalt binder by different weight ratios. An asphalt penetration test, softening point test, ductility test and dynamic viscoelastic behavior were conducted to characterize and predict the ceramic fiber modified asphalt mortar (CFAM). Research results indicated that the ceramic fiber has a great effect on reinforcement of asphalt, which makes the asphalt stiffer so that the asphalt can only undertake less strain under the same stress. The heat insulation effect of the ceramic fiber will improve the temperature stability. Complex modulus and phase angle results indicate that the ceramic fiber can significantly enhance the high temperature resistance of soft binder. PMID:28773908

Characteristics of Ceramic Fiber Modified Asphalt Mortar.

PubMed

Wan, Jiuming; Wu, Shaopeng; Xiao, Yue; Liu, Quantao; Schlangen, Erik

2016-09-21

Ceramic fiber, with a major composition of Al₂O₃ and SiO₂, has advantages of stability at relatively high temperature, big specific surface area and resistance to external mechanical vibration. It has the potential contribution of improving the rutting resistance and temperature sensitivity of modified asphalt binder by proper modification design. In this research, ceramic fiber was introduced into both pen 60/80 and pen 80/100 asphalt binder by different weight ratios. An asphalt penetration test, softening point test, ductility test and dynamic viscoelastic behavior were conducted to characterize and predict the ceramic fiber modified asphalt mortar (CFAM). Research results indicated that the ceramic fiber has a great effect on reinforcement of asphalt, which makes the asphalt stiffer so that the asphalt can only undertake less strain under the same stress. The heat insulation effect of the ceramic fiber will improve the temperature stability. Complex modulus and phase angle results indicate that the ceramic fiber can significantly enhance the high temperature resistance of soft binder.

Feature extraction for ultrasonic sensor based defect detection in ceramic components

NASA Astrophysics Data System (ADS)

Kesharaju, Manasa; Nagarajah, Romesh

2014-02-01

High density silicon carbide materials are commonly used as the ceramic element of hard armour inserts used in traditional body armour systems to reduce their weight, while providing improved hardness, strength and elastic response to stress. Currently, armour ceramic tiles are inspected visually offline using an X-ray technique that is time consuming and very expensive. In addition, from X-rays multiple defects are also misinterpreted as single defects. Therefore, to address these problems the ultrasonic non-destructive approach is being investigated. Ultrasound based inspection would be far more cost effective and reliable as the methodology is applicable for on-line quality control including implementation of accept/reject criteria. This paper describes a recently developed methodology to detect, locate and classify various manufacturing defects in ceramic tiles using sub band coding of ultrasonic test signals. The wavelet transform is applied to the ultrasonic signal and wavelet coefficients in the different frequency bands are extracted and used as input features to an artificial neural network (ANN) for purposes of signal classification. Two different classifiers, using artificial neural networks (supervised) and clustering (un-supervised) are supplied with features selected using Principal Component Analysis(PCA) and their classification performance compared. This investigation establishes experimentally that Principal Component Analysis(PCA) can be effectively used as a feature selection method that provides superior results for classifying various defects in the context of ultrasonic inspection in comparison with the X-ray technique.

Structure and bioactivity studies of new polysiloxane-derived materials for orthopedic applications

NASA Astrophysics Data System (ADS)

Paluszkiewicz, Czesława; Gumuła, Teresa; Podporska, Joanna; Błażewicz, Marta

2006-07-01

The aim of this work was to examine the structure of new calcium silicate bioactive ceramic implant material for bone surgery applications. The bioceramic material was obtained by thermal treatment of active fillers-containing organosilicon polymer precursor. Different ceramic active fillers, namely Ca(OH) 2, CaCO 3, Na 2HPO 4 and SiO 2 powders were used. The phase composition of ceramic samples obtained by thermal transformation of active fillers containing polysiloxane was investigated. Morphology and structure of ceramic phases were characterized by means of scanning electron microscopy (SEM) with EDS point analysis, FTIR spectroscopy and XRD analysis. It was found that thermal treatment of active fillers-containing organosilicon precursor lead to the formation of wollastonite-containing ceramic material. This ceramic material showed bioactivity in 'in vitro' conditions studied by immersing the samples in simulated body fluid (SBF). The surface of wollastonite-containing ceramic before and after immersion in SBF was analysed. It can be concluded that this kind of ceramic material may be useful as bone substitute. FTIR spectroscopy is an adequate device for the determination of such derived materials structure.

Characterization of ion beam modified ceramic wear surfaces using Auger electron spectroscopy

NASA Technical Reports Server (NTRS)

Wei, W.; Lankford, J.

1987-01-01

An investigation of the surface chemistry and morphology of the wear surfaces of ceramic material surfaces modified by ion beam mixing has been conducted using Auger electron spectroscopy and secondary electron microscopy. Studies have been conducted on ceramic/ceramic friction and wear couples made up of TiC and NiMo-bonded TiC cermet pins run against Si3N4 and partially stabilized zirconia disc surfaces modified by the ion beam mixing of titanium and nickel, as well as ummodified ceramic/ceramic couples in order to determine the types of surface changes leading to the improved friction and wear behavior of the surface modified ceramics in simulated diesel environments. The results of the surface analyses indicate that the formation of a lubricating oxide layer of titanium and nickel, is responsible for the improvement in ceramic friction and wear behavior. The beneficial effect of this oxide layer depends on several factors, including the adherence of the surface modified layer or subsequently formed oxide layer to the disc substrate, the substrate materials, the conditions of ion beam mixing, and the environmental conditions.

Dispersed metal-toughened ceramics and ceramic brazing

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

Moorhead, A.J.; Tiegs, T.N.; Lauf, R.J.

1983-01-01

An alumina (Al/sub 2/O/sub 3/) based material that contains approximately 1 vol % finely dispersed platinum or chromium was developed for use in high temperature thermal-shock resistant electrical insulators. The work at ORNL is divided into two areas: (1) development of DMT ceramics; and (2) development of brazing filler metals suitable for making ceramic-to-ceramic and ceramic-to-metal brazements. The DMT ceramics and brazements are intended for service at elevated temperatures and at high stress levels in the dirty environments of advanced heat engines. The development and characterization of DMT ceramics includes processing (powder preparation, densification and heat treatment) and detailed measurementmore » of mechanical and physical properties (strength, fracture toughness, and thermal conductivity). The brazing work includes: (1) the formulation and melting of small quantities of experimental brazing filler metals; (2) evaluation of the wetting and bonding behavior of these filler metals on Al/sub 2/O/sub 3/, partially stabilized zirconia and ..cap alpha..-SiC in a sessile drop apparatus; and (3) determine the short-term strength and fracture toughness of brazements.« less

Characterization of damage modes in dental ceramic bilayer structures.

PubMed

Deng, Yan; Lawn, Brian R; Lloyd, Isabel K

2002-01-01

Results of contact tests using spherical indenters on flat ceramic coating layers bonded to compliant substrates are reported for selected dental ceramics. Critical loads to produce various damage modes, cone cracking, and quasiplasticity at the top surfaces and radial cracking at the lower (inner) surfaces are measured as a function of ceramic-layer thickness. It is proposed that these damage modes, especially radial cracking, are directly relevant to the failure of all-ceramic dental crowns. The critical load data are analyzed with the use of explicit fracture-mechanics relations, expressible in terms of routinely measurable material parameters (elastic modulus, strength, toughness, hardness) and essential geometrical variables (layer thickness, contact radius). The utility of such analyses in the design of ceramic/substrate bilayer systems for optimal resistance to lifetime-threatening damage is discussed. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 137--145, 2002; DOI 10.1002/jbm.10091

High-Temperature Dielectric Properties of Aluminum Nitride Ceramic for Wireless Passive Sensing Applications

PubMed Central

Liu, Jun; Yuan, Yukun; Ren, Zhong; Tan, Qiulin; Xiong, Jijun

2015-01-01

The accurate characterization of the temperature-dependent permittivity of aluminum nitride (AlN) ceramic is quite critical to the application of wireless passive sensors for harsh environments. Since the change of the temperature-dependent permittivity will vary the ceramic-based capacitance, which can be converted into the change of the resonant frequency, an LC resonator, based on AlN ceramic, is prepared by the thick film technology. The dielectric properties of AlN ceramic are measured by the wireless coupling method, and discussed within the temperature range of 12 °C (room temperature) to 600 °C. The results show that the extracted relative permittivity of ceramic at room temperature is 2.3% higher than the nominal value of 9, and increases from 9.21 to 10.79, and the quality factor Q is decreased from 29.77 at room temperature to 3.61 at 600 °C within the temperature range. PMID:26370999

FY2016 Ceramic Fuels Development Annual Highlights

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

Mcclellan, Kenneth James

Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2016 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts.more » Accomplishments for FY16 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.« less

Morphologies, Processing and Properties of Ceramic Foams from Pre-Ceramic Foams from Pre-Ceramic Polymer Routes

NASA Technical Reports Server (NTRS)

Stackpoole, Mairead; Simoes, Conan R.; Venkatapathy, Ethiras (Technical Monitor)

2002-01-01

The current research is focused on processing ceramic foams that have potential as a thermal protection material. Ceramic foams with different architectures were formed from the pyrolysis of pre-ceramic polymers at 1200 C in different atmospheres. In some systems a sacrificial polyurethane was used as the blowing agent. We have also processed foams using sacrificial fillers to introduce controlled cell sizes. Each sacrificial filler or blowing agent leads to a unique morphology. The effect of different fillers on foam morphologies will be presented. The presentation will also focus on characterization of these foams in terms of mechanical and thermal properties. Foams processed using these approaches having bulk densities ranging from 0.15 to 0.9 g per cubic centimeter and a cell sizes from 5 to 500 micrometers. Compression strengths ranged from 2 to 7 MPa for these materials.

A study on (K, Na) NbO3 based multilayer piezoelectric ceramics micro speaker

NASA Astrophysics Data System (ADS)

Gao, Renlong; Chu, Xiangcheng; Huan, Yu; Sun, Yiming; Liu, Jiayi; Wang, Xiaohui; Li, Longtu

2014-10-01

A flat panel micro speaker was fabricated from (K, Na) NbO3 (KNN)-based multilayer piezoelectric ceramics by a tape casting and cofiring process using Ag-Pd alloys as an inner electrode. The interface between ceramic and electrode was investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The acoustic response was characterized by a standard audio test system. We found that the micro speaker with dimensions of 23 × 27 × 0.6 mm3, using three layers of 30 μm thickness KNN-based ceramic, has a high average sound pressure level (SPL) of 87 dB, between 100 Hz-20 kHz under five voltage. This result was even better than that of lead zirconate titanate (PZT)-based ceramics under the same conditions. The experimental results show that the KNN-based multilayer ceramics could be used as lead free piezoelectric micro speakers.

Oxide Ceramic Films Grown on 60 Nitinol for NASA and Department of Defense Applications

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Street, Kenneth W.; Lukco, Dorothy; Cytron, Sheldon J.

2005-01-01

Both the NASA Glenn Research Center and the U.S. Army Research Laboratory, Development and Engineering Center (ARDEC) have worked to develop oxide ceramic films grown on 60 nitinol (60-wt% nickel and 40-wt% titanium) to decrease friction and increase wear resistance under unlubricated conditions. In general, oxide and nonoxide ceramic films have unique capabilities as mechanical-, chemical-, and thermal-barrier materials in diverse applications, including high-temperature bearings and gas bearings requiring low friction, wear resistance, and chemical stability. All oxide ceramic films grown on 60 nitinol were furnished by ARDEC, and materials and surface characterization and tribological experiments were conducted at Glenn.

Screen-Cage Ion Plating Of Silver On Polycrystalline Alumina

NASA Technical Reports Server (NTRS)

Spalvins, Talivaldis; Sliney, Harold E.; Deadmore, Daniel L.

1995-01-01

Screen-cage ion plating (SCIP) cost-effective technique offering high throwing power for deposition of adherent metal films on ceramic substrates. Applies silver films to complexly shaped substrates of polycrystalline alumina. Silver adheres tenaciously and reduces friction. SCIP holds promise for applying lubricating soft metallic films to high-temperature ceramic components of advanced combustion engines. Other potential uses include coating substrates with metal for protection against corrosion, depositing electrical conductors on dielectric substrates, making optically reflective or electrically or thermally conductive surface layers, and applying decorative metal coats to ceramic trophies or sculptures.

Critical Needs for Robust and Reliable Database for Design and Manufacturing of Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Singh, M.

1999-01-01

Ceramic matrix composite (CMC) components are being designed, fabricated, and tested for a number of high temperature, high performance applications in aerospace and ground based systems. The critical need for and the role of reliable and robust databases for the design and manufacturing of ceramic matrix composites are presented. A number of issues related to engineering design, manufacturing technologies, joining, and attachment technologies, are also discussed. Examples of various ongoing activities in the area of composite databases. designing to codes and standards, and design for manufacturing are given.

Computer-aided study of key factors determining high mechanical properties of nanostructured surface layers in metal-ceramic composites

NASA Astrophysics Data System (ADS)

Konovalenko, Igor S.; Shilko, Evgeny V.; Ovcharenko, Vladimir E.; Psakhie, Sergey G.

2017-12-01

The paper presents the movable cellular automaton method. It is based on numerical models of surface layers of the metal-ceramic composite NiCr-TiC modified under electron beam irradiation in inert gas plasmas. The models take into account different geometric, concentration and mechanical parameters of ceramic and metallic components. The authors study the contributions of key structural factors in mechanical properties of surface layers and determine the ranges of their variations by providing the optimum balance of strength, strain hardening and fracture toughness.

Ceramic thermal barrier coatings for commercial gas turbine engines

NASA Technical Reports Server (NTRS)

Meier, Susan Manning; Gupta, Dinesh K.; Sheffler, Keith D.

1991-01-01

The paper provides an overview of the short history, current status, and future prospects of ceramic thermal barrier coatings for gas turbine engines. Particular attention is given to plasma-sprayed and electron beam-physical vapor deposited yttria-stabilized (7 wt pct Y2O3) zirconia systems. Recent advances include improvements in the spallation life of thermal barrier coatings, improved bond coat composition and spraying techniques, and improved component design. The discussion also covers field experience, life prediction modeling, and future directions in ceramic coatings in relation to gas turbine engine design.

Ceramic on ceramic arthroplasty of the hip: new materials confirm appropriate use in young patients.

PubMed

Sentuerk, U; von Roth, P; Perka, C

2016-01-01

The leading indication for revision total hip arthroplasty (THA) remains aseptic loosening owing to wear. The younger, more active patients currently undergoing THA present unprecedented demands on the bearings. Ceramic-on-ceramic (CoC) bearings have consistently shown the lowest rates of wear. The recent advances, especially involving alumina/zirconia composite ceramic, have led to substantial improvements and good results in vitro. Alumina/zirconia composite ceramics are extremely hard, scratch resistant and biocompatible. They offer a low co-efficient of friction and superior lubrication and lower rates of wear compared with other bearings. The major disadvantage is the risk of fracture of the ceramic. The new composite ceramic has reduced the risk of fracture of the femoral head to 0.002%. The risk of fracture of the liner is slightly higher (0.02%). Assuming that the components are introduced without impingement, CoC bearings have major advantages over other bearings. Owing to the superior hardness, they produce less third body wear and are less vulnerable to intra-operative damage. The improved tribology means that CoC bearings are an excellent choice for young, active patients requiring THA. ©2016 The British Editorial Society of Bone & Joint Surgery.

Advanced Material-Ordered Nanotubular Ceramic Membranes Covalently Capped with Single-Wall Carbon Nanotubes.

PubMed

Al-Gharabli, Samer; Hamad, Eyad; Saket, Munib; Abu El-Rub, Ziad; Arafat, Hassan; Kujawski, Wojciech; Kujawa, Joanna

2018-05-07

Advanced ceramic materials with a well-defined nano-architecture of their surfaces were formed by applying a two-step procedure. Firstly, a primary amine was docked on the ordered nanotubular ceramic surface via a silanization process. Subsequently, single-wall carbon nanotubes (SWCNTs) were covalently grafted onto the surface via an amide building block. Physicochemical (e.g., hydrophobicity, and surface free energy (SFE)), mechanical, and tribological properties of the developed membranes were improved significantly. The design, preparation, and extended characterization of the developed membranes are presented. Tools such as high-resolution transmission electron microscopy (HR-TEM), single-area electron diffraction (SAED) analysis, microscopy, tribology, nano-indentation, and Raman spectroscopy, among other techniques, were utilized in the characterization of the developed membranes. As an effect of hydrophobization, the contact angles (CAs) changed from 38° to 110° and from 51° to 95° for the silanization of ceramic membranes 20 (CM20) and CM100, respectively. SWCNT functionalization reduced the CAs to 72° and 66° for ceramic membranes carbon nanotubes 20 (CM-CNT-20) and CM-CNT-100, respectively. The mechanical properties of the developed membranes improved significantly. From the nanotribological study, Young’s modulus increased from 3 to 39 GPa for CM-CNT-20 and from 43 to 48 GPa for pristine CM-CNT-100. Furthermore, the nanohardness increased by about 80% after the attachment of CNTs for both types of ceramics. The proposed protocol within this work for the development of functionalized ceramic membranes is both simple and efficient.

Determination of elastic modulus of ceramics using ultrasonic testing

NASA Astrophysics Data System (ADS)

Sasmita, Firmansyah; Wibisono, Gatot; Judawisastra, Hermawan; Priambodo, Toni Agung

2018-04-01

Elastic modulus is important material property on structural ceramics application. However, bending test as a common method for determining this property require particular specimen preparation. Furthermore, elastic modulus of ceramics could vary because it depends on porosity content. For structural ceramics industry, such as ceramic tiles, this property is very important. This drives the development of new method to improve effectivity or verification method as well. In this research, ultrasonic testing was conducted to determine elastic modulus of soda lime glass and ceramic tiles. The experiment parameter was frequency of probe (1, 2, 4 MHz). Characterization of density and porosity were also done for analysis. Results from ultrasonic testing were compared with elastic modulus resulted from bending test. Elastic modulus of soda-lime glass based on ultrasonic testing showed excellent result with error 2.69% for 2 MHz probe relative to bending test result. Testing on red and white ceramic tiles were still contained error up to 41% and 158%, respectively. The results for red ceramic tile showed trend that 1 MHz probe gave better accuracy in determining elastic modulus. However, testing on white ceramic tile showed different trend. It was due to the presence of porosity and near field effect.

Characterization of the Sol-Gel Transition for Zirconia-Toughened Alumina Precursors

NASA Technical Reports Server (NTRS)

Moeti, I.; Karikari, E.; Chen, J.

1998-01-01

High purity ZTA ceramic powders with and without yttria were produced using metal alkoxide precursors. ZTA ceramic powders with varying volume percents of zirconia were prepared (7, 15, and 22%). Aluminum tri-sec butoxide, zirconium propoxide, and yttrium isopropoxide were the reagents used. Synthesis conditions were varied to control the hydrolysis and the aging conditions for the sol to gel transition. FTIR analysis and theological characterization were used to follow the structural evolution during the sol to gel transition. The greater extent of hydrolysis and the build-up of structure measured from viscoelastic properties were consistent. Heat treatment was conducted to produce submicron grain fully crystalline ZTA ceramic powders. In all experimental cases a-alumina and tetragonal zirconia phases were confirmed even in the absence of yttria.

Modeling the impact behavior of high strength ceramics. Final report

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

Rajendran, A.M.

1993-12-01

An advanced constitutive model is used to describe the shock and high strain rate behaviors of silicon carbide (SC), boron carbide B4C, and titanium diboride (TiB2) under impact loading conditions. The model's governing equations utilize a set of microphysically-based constitutive relationships to model the deformation and damage processes in a ceramic. The total strain is decomposed into elastic, plastic, and microcracking components. The plastic strain component was calculated using conventional viscoplastic equations. The strain components due to microcracking utilized relationships derived for a penny-shaped crack containing elastic solids. The main features of the model include degradation of strength and stiffnessmore » under both compressive and tensile loading conditions. When loaded above the Hugoniot elastic limit (HEL), the strength is limited by the strain rate dependent strength equation. However, below the HEL, the strength variation with respect to strain rate and pressure is modeled through microcracking relationships assuming no plastic flow. The ceramic model parameters were determined using a set of VISAR data from the plate impact experiments.« less

Thermal barrier coating life prediction model development

NASA Technical Reports Server (NTRS)

Sheffler, K. D.; Demasi, J. T.

1985-01-01

A methodology was established to predict thermal barrier coating life in an environment simulative of that experienced by gas turbine airfoils. Specifically, work is being conducted to determine failure modes of thermal barrier coatings in the aircraft engine environment. Analytical studies coupled with appropriate physical and mechanical property determinations are being employed to derive coating life prediction model(s) on the important failure mode(s). An initial review of experimental and flight service components indicates that the predominant mode of TBC failure involves thermomechanical spallation of the ceramic coating layer. This ceramic spallation involves the formation of a dominant crack in the ceramic coating parallel to and closely adjacent to the metal-ceramic interface. Initial results from a laboratory test program designed to study the influence of various driving forces such as temperature, thermal cycle frequency, environment, and coating thickness, on ceramic coating spalling life suggest that bond coat oxidation damage at the metal-ceramic interface contributes significantly to thermomechanical cracking in the ceramic layer. Low cycle rate furnace testing in air and in argon clearly shows a dramatic increase of spalling life in the non-oxidizing environments.

Ceramic technology for advanced heat engines project. Semiannual progress report, October 1985-March 1986

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

Not Available

1986-08-01

Significant accomplishments in fabricating cermaic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DOD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, additional research is needed in materials and processing development, design methodology, and data base and life prediction. An assessment of needs was completed, and a five-year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotivemore » heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines.« less

Comparative characterization of a novel cad-cam polymer-infiltrated-ceramic-network

PubMed Central

Pascual, Agustín; Camps, Isabel; Grau-Benitez, María

2015-01-01

Background The field of dental ceramics for CAD-CAM is enriched with a new innovative material composition having a porous three-dimensional structure of feldspathic ceramic infiltrated with acrylic resins.The aim of this study is to determine the mechanical properties of Polymer-Infiltrated-Ceramic-Network (PICN) and compare its performance with other ceramics and a nano-ceramic resin available for CAD-CAM systems. Material and Methods In this study a total of five different materials for CAD-CAM were investigated. A polymer-infiltrated ceramic (Vita Enamic), a nano-ceramic resin (Lava Ultimate), a feldspathic ceramic (Mark II), a lithium disilicate ceramic (IPS-e max CAD) and finally a Leucite based ceramic (Empress - CAD). From CAD-CAM blocks, 120 bars (30 for each material cited above) were cut to measure the flexural strength with a three-point-bending test. Strain at failure, fracture stress and Weibull modulus was calculated. Vickers hardness of each material was also measured. Results IPS-EMAX presents mechanical properties significantly better from the other materials studied. Its strain at failure, flexural strength and hardness exhibited significantly higher values in comparison with the others. VITA ENAMIC and LAVA ULTIMATE stand out as the next most resistant materials. Conclusions The flexural strength, elastic modulus similar to a tooth as well as having less hardness than ceramics make PICN materials an option to consider as a restorative material. Key words:Ceramic infiltrated with resin, CAD-CAM, Weibull modulus, flexural strength, micro hardness. PMID:26535096

Investigation of Laser Generation and Detection of Ultrasound in Ceramic Matrix Composites and Intermetallics

NASA Technical Reports Server (NTRS)

Ehrlich, Michael J.

1998-01-01

The goal of this program is to assess the feasibility of using laser based ultrasonic techniques for inspecting and characterizing materials of interest to NASA, specifically those used in propulsion and turbomachinery applications, such as ceramic composites, metal matrix composites, and intermetallics.

Characterization of fatigue behavior of 2-D woven fabric reinforced ceramic matrix composite at elevated temperature. Final report

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

Groner, D.J.

This study investigated the fatigue behavior and associated damage mechanisms in notched and unnotched enhanced SiC/SiC ceramic matrix composite specimens at 1100 deg C. Stiffness degradation, strain variation, and hysteresis were evaluated to characterize material behavior. Microscopic examination was performed to characterize damage mechanisms. During high cycle/low stress fatigue tests, far less fiber/matrix interface debond was evident than in low cycle/high stress fatigue tests. Notched specimens exhibited minimal stress concentration during monotonic tensile testing and minimal notch sensitivity during fatigue testing. Damage mechanisms were also similar to unnotched.

Saturation-resolved-fluorescence spectroscopy of Cr3+:mullite glass ceramic

NASA Astrophysics Data System (ADS)

Liu, Huimin; Knutson, Robert; Yen, W. M.

1990-01-01

We present a saturation-based technique designed to isolate and uncouple individual components of inhomogeneously broadened spectra that are simultaneously coupled to each other through spectral overlap and energy-transfer interactions. We have termed the technique saturation-resolved-fluorescence spectroscopy; we demonstrate its usefulness in deconvoluting the complex spectra of Cr3+:mullite glass ceramic.

Ceramic Integration Technologies for Energy and Aerospace Applications

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Asthana, Ralph N.

2007-01-01

Robust and affordable integration technologies for advanced ceramics are required to improve the performance, reliability, efficiency, and durability of components, devices, and systems based on them in a wide variety of energy, aerospace, and environmental applications. Many thermochemical and thermomechanical factors including joint design, analysis, and optimization must be considered in integration of similar and dissimilar material systems.