Corrosion Behavior and Microstructure Influence of Glass-Ceramic Nuclear Waste Forms

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

Matthew Asmussen, R.; Neeway, James J.; Kaspar, Tiffany C.

Glass ceramic waste forms present a potentially viable technology for the long term immobilization and disposal of liquid nuclear wastes. Through control of chemistry during fabrication, such waste forms can have designed secondary crystalline phases within a borosilicate glass matrix. In this work, a glass ceramic containing powellite and oxyapatite secondary phases was tested for its corrosion properties in dilute conditions using single pass flow through testing (SPFT). Three glass ceramic samples were prepared using different cooling rates to produce samples with varying microstructure sizes. In testing at 90 °C in buffered pH 7 and pH 9 solutions, it wasmore » found that increasing pH and decreasing microstructure size (resulting from rapid cooling during fabrication) both led to a reduction in overall corrosion rate. The phases of the glass ceramic were found, using a combination of solutions analysis, SEM and AFM, to corrode preferably in the order of powellite > bulk glass matrix > oxyapatite.« less

Commercial high-level-waste management: Options and economics. A comparative analysis of the ceramic and glass waste forms

NASA Astrophysics Data System (ADS)

McKisson, R. L.; Grantham, L. F.; Guon, J.; Recht, H. L.

1983-02-01

Results of an estimate of the waste management costs of the commercial high level waste from a 3000 metric ton per year reprocessing plant show that the judicious use of the ceramic waste form can save about $2 billion during a 20 year operating campaign relative to the use of the glass waste form. This assumes PWR fuel is processed and the waste is encapsulated in 0.305-m-diam canisters with ultimate emplacement in a BWIP-type horizontal-borehole repository. Waste loading and waste form density are the driving factors in that the low waste loading (25%) and relatively low density (3.1 g cu cm) characteristic of the glass form require several times as many canisters to handle a given waste throughput than is needed for the ceramic waste form whose waste loading capability exceeds 60% and whose waste density is nominally 5.2 cu cm.

Compression deformation of WC: atomistic description of hard ceramic material

NASA Astrophysics Data System (ADS)

Feng, Qing; Song, Xiaoyan; Liu, Xuemei; Liang, Shuhua; Wang, Haibin; Nie, Zuoren

2017-11-01

The deformation characteristics of WC, as a typical hard ceramic material, were studied on the nanoscale using atomistic simulations for both the single-crystal and polycrystalline forms under uniaxial compression. In particular, the effects of crystallographic orientation, grain boundary coordination and grain size on the origin of deformation were investigated. The deformation behavior of the single-crystal and polycrystalline WC both depend strongly on the orientation towards the loading direction. The grain boundaries play a significant role in the deformation coordination and the potential high fracture toughness of the nanocrystalline WC. In contrast to conventional knowledge of ceramics, maximum strength was obtained at a critical grain size corresponding to the turning point from a Hall-Petch to an inverse Hall-Petch relationship. For this the mechanism of the combined effect of dislocation motion within grains and the coordination of stress concentration at the grain boundaries were proposed. The present work has moved forward our understanding of plastic deformability and the possibility of achieving a high strength of nanocrystalline ceramic materials.

Compression deformation of WC: atomistic description of hard ceramic material.

PubMed

Feng, Qing; Song, Xiaoyan; Liu, Xuemei; Liang, Shuhua; Wang, Haibin; Nie, Zuoren

2017-11-24

The deformation characteristics of WC, as a typical hard ceramic material, were studied on the nanoscale using atomistic simulations for both the single-crystal and polycrystalline forms under uniaxial compression. In particular, the effects of crystallographic orientation, grain boundary coordination and grain size on the origin of deformation were investigated. The deformation behavior of the single-crystal and polycrystalline WC both depend strongly on the orientation towards the loading direction. The grain boundaries play a significant role in the deformation coordination and the potential high fracture toughness of the nanocrystalline WC. In contrast to conventional knowledge of ceramics, maximum strength was obtained at a critical grain size corresponding to the turning point from a Hall-Petch to an inverse Hall-Petch relationship. For this the mechanism of the combined effect of dislocation motion within grains and the coordination of stress concentration at the grain boundaries were proposed. The present work has moved forward our understanding of plastic deformability and the possibility of achieving a high strength of nanocrystalline ceramic materials.

Reactive Processing of Environmentally Conscious, Biomorphic Ceramics from Natural Wood Precursors

NASA Technical Reports Server (NTRS)

Singh, M.; Yee, Bo-Moon

2003-01-01

Environmentally conscious, biomorphic ceramics (Ecoceramics) are a new class of materials that are manufactured from renewable resources and wastes. In this study, silicon carbide and oxide-based biomorphic ceramics have been fabricated from pine and jelutong wood precursors. A carbonaceous preform is produced through wood pyrolysis and subsequent infiltration with oxides (ZrO2 sols) and liquid silicon to form ceramics. These biomorphic ceramics show a wide variety of microstructures, densities, and hardness behavior that are determined by the type of wood and infiltrants selected.

Melt processed crystalline ceramic waste forms for advanced nuclear fuel cycles: CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, task 17208: Final report

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

Amoroso, J. W.; Marra, J. C.

2015-08-26

A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics)more » over geologic timescales of interest for nuclear waste immobilization [1]. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).« less

Melt processed crystalline ceramic waste forms for advanced nuclear fuel cycles: CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, Task 17208: Final report

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

Amoroso, J. W.; Marra, J. C.

2015-08-26

A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics)more » over geologic timescales of interest for nuclear waste immobilization [1]. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).« less

Glass binder development for a glass-bonded sodalite ceramic waste form

NASA Astrophysics Data System (ADS)

Riley, Brian J.; Vienna, John D.; Frank, Steven M.; Kroll, Jared O.; Peterson, Jacob A.; Canfield, Nathan L.; Zhu, Zihua; Zhang, Jiandong; Kruska, Karen; Schreiber, Daniel K.; Crum, Jarrod V.

2017-06-01

This paper discusses work to develop Na2O-B2O3-SiO2 glass binders for immobilizing LiCl-KCl eutectic salt waste in a glass-bonded sodalite waste form following electrochemical reprocessing of used metallic nuclear fuel. Here, five new glasses with ∼20 mass% Na2O were designed to generate waste forms with high sodalite. The glasses were then used to produce ceramic waste forms with a surrogate salt waste. The waste forms made using these new glasses were formulated to generate more sodalite than those made with previous baseline glasses for this type of waste. The coefficients of thermal expansion for the glass phase in the glass-bonded sodalite waste forms made with the new binder glasses were closer to the sodalite phase in the critical temperature region near and below the glass transition temperature than previous binder glasses used. These improvements should result in lower probability of cracking in the full-scale monolithic ceramic waste form, leading to better long-term chemical durability.

Glass binder development for a glass-bonded sodalite ceramic waste form

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

Riley, Brian J.; Vienna, John D.; Frank, Steven M.

This paper discusses work to develop Na 2O-B 2O 3-SiO 2 glass binders for immobilizing LiCl-KCl eutectic salt waste in a glass-bonded sodalite waste form following electrochemical reprocessing of used metallic nuclear fuel. In this paper, five new glasses with ~20 mass% Na 2O were designed to generate waste forms with high sodalite. The glasses were then used to produce ceramic waste forms with a surrogate salt waste. The waste forms made using these new glasses were formulated to generate more sodalite than those made with previous baseline glasses for this type of waste. The coefficients of thermal expansion formore » the glass phase in the glass-bonded sodalite waste forms made with the new binder glasses were closer to the sodalite phase in the critical temperature region near and below the glass transition temperature than previous binder glasses used. Finally, these improvements should result in lower probability of cracking in the full-scale monolithic ceramic waste form, leading to better long-term chemical durability.« less

Glass binder development for a glass-bonded sodalite ceramic waste form

DOE PAGES

Riley, Brian J.; Vienna, John D.; Frank, Steven M.; ...

2017-06-01

This paper discusses work to develop Na 2O-B 2O 3-SiO 2 glass binders for immobilizing LiCl-KCl eutectic salt waste in a glass-bonded sodalite waste form following electrochemical reprocessing of used metallic nuclear fuel. In this paper, five new glasses with ~20 mass% Na 2O were designed to generate waste forms with high sodalite. The glasses were then used to produce ceramic waste forms with a surrogate salt waste. The waste forms made using these new glasses were formulated to generate more sodalite than those made with previous baseline glasses for this type of waste. The coefficients of thermal expansion formore » the glass phase in the glass-bonded sodalite waste forms made with the new binder glasses were closer to the sodalite phase in the critical temperature region near and below the glass transition temperature than previous binder glasses used. Finally, these improvements should result in lower probability of cracking in the full-scale monolithic ceramic waste form, leading to better long-term chemical durability.« less

Commercialization of Ultra-Hard Ceramics for Cutting Tools Final Report CRADA No. TC0279.0

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

Landingham, R.; Neumann, T.

This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and Greenleaf Corporation (Greenleaf) to develop the technology for forming unique precursor nano-powders process that can be consolidated into ceramic products for industry. LLNL researchers have developed a solgel process for forming nano-ceramic powders. The nano powders are highly tailorable, allowing the explicit design of desired properties that lead to ultra hard materials with fine grain size. The present CRADA would allow the two parties to continue the development of the sol-gel process and the consolidation process in ordermore » to develop an industrially sound process for the manufacture of these ultra-hard materials.« less

In situ plasma fabrication of ceramic-like structure on polymeric implant with enhanced surface hardness, cytocompatibility and antibacterial capability.

PubMed

Liu, Jun; Zhang, Wei; Shi, Haigang; Yang, Kun; Wang, Gexia; Wang, Pingli; Ji, Junhui; Chu, Paul K

2016-05-01

Polymeric materials are commonly found in orthopedic implants due to their unique mechanical properties and biocompatibility but the poor surface hardness and bacterial infection hamper many biomedical applications. In this study, a ceramic-like surface structure doped with silver is produced by successive plasma implantation of silicon (Si) and silver (Ag) into the polyamine 66 (PA66) substrate. Not only the surface hardness and elastic modulus are greatly enhanced due to the partial surface carbonization and the ceramic-like structure produced by the reaction between energetic Si and the carbon chain of PA66, but also the antibacterial activity is improved because of the combined effects rendered by Ag and SiC structure. Furthermore, the modified materials which exhibit good cytocompatibility upregulate bone-related genes and proteins expressions of the contacted bone mesenchymal stem cells (BMSCs). For the first time, it explores out that BMSCs osteogenesis on the antibacterial ceramic-like structure is mediated via the iNOS and nNOS signal pathways. The results reveal that in situ plasma fabrication of an antibacterial ceramic-like structure can endow PA66 with excellent surface hardness, cytocompatibility, as well as antibacterial capability. © 2016 Wiley Periodicals, Inc.

Disposal of waste computer hard disk drive: data destruction and resources recycling.

PubMed

Yan, Guoqing; Xue, Mianqiang; Xu, Zhenming

2013-06-01

An increasing quantity of discarded computers is accompanied by a sharp increase in the number of hard disk drives to be eliminated. A waste hard disk drive is a special form of waste electrical and electronic equipment because it holds large amounts of information that is closely connected with its user. Therefore, the treatment of waste hard disk drives is an urgent issue in terms of data security, environmental protection and sustainable development. In the present study the degaussing method was adopted to destroy the residual data on the waste hard disk drives and the housing of the disks was used as an example to explore the coating removal process, which is the most important pretreatment for aluminium alloy recycling. The key operation points of the degaussing determined were: (1) keep the platter plate parallel with the magnetic field direction; and (2) the enlargement of magnetic field intensity B and action time t can lead to a significant upgrade in the degaussing effect. The coating removal experiment indicated that heating the waste hard disk drives housing at a temperature of 400 °C for 24 min was the optimum condition. A novel integrated technique for the treatment of waste hard disk drives is proposed herein. This technique offers the possibility of destroying residual data, recycling the recovered resources and disposing of the disks in an environmentally friendly manner.

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.

Ion Selective Ceramics for Waste Separations. Input for Annual Accomplishments Report

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

Spoerke, Erik David

This report discusses“Ion-Selective Ceramics for Waste Separations” which aims to develop an electrochemical approach to remove fission product waste (e.g., Cs+ ) from the LiCl-KCl molten salts used in the pyroprocessing of spent nuclear fuel.

FT-IR characterization of articulated ceramic bricks with wastes from ceramic industries

NASA Astrophysics Data System (ADS)

Nirmala, G.; Viruthagiri, G.

The 30 ceramic test samples with the kaolinitic clay and ceramic rejects (in the as-received state and sintered at temperatures 900-1200 °C) were investigated through spectral studies in order to elucidate the possibility of recycling the wastes from the government ceramic industry of Vriddhachalam, Tamilnadu state, South India. A detailed attribution of all the spectroscopic frequencies in the spectra recorded in the 4000-400 cm-1 region was attempted and their assignment to different minerals was accomplished. X-ray diffraction analysis was performed to demonstrate the reliability of IR attributions. The indication of well-ordered kaolinite is by the band at 1115 cm-1 in the raw samples which tends to shift towards 1095 cm-1 in all the fired samples. The peaks at 563 cm-1 and 795 cm-1 can be assigned to anorthite and dickite respectively. The presence of quartz and anorthite is confirmed both by XRD and FTIR. The microstructural observations were done through the SEM images which visualized the vitrification of the fired bricks at higher temperatures. The refractory properties of the samples found through the XRF analysis are also appreciable. The present work suggests that the incorporation of the rejects into the clay mixture will be a valid route for the ceramic industries to reduce the costs of the ceramic process.

FT-IR characterization of articulated ceramic bricks with wastes from ceramic industries.

PubMed

Nirmala, G; Viruthagiri, G

2014-05-21

The 30 ceramic test samples with the kaolinitic clay and ceramic rejects (in the as-received state and sintered at temperatures 900-1200°C) were investigated through spectral studies in order to elucidate the possibility of recycling the wastes from the government ceramic industry of Vriddhachalam, Tamilnadu state, South India. A detailed attribution of all the spectroscopic frequencies in the spectra recorded in the 4000-400cm(-1) region was attempted and their assignment to different minerals was accomplished. X-ray diffraction analysis was performed to demonstrate the reliability of IR attributions. The indication of well-ordered kaolinite is by the band at 1115cm(-1) in the raw samples which tends to shift towards 1095cm(-1) in all the fired samples. The peaks at 563cm(-1) and 795cm(-1) can be assigned to anorthite and dickite respectively. The presence of quartz and anorthite is confirmed both by XRD and FTIR. The microstructural observations were done through the SEM images which visualized the vitrification of the fired bricks at higher temperatures. The refractory properties of the samples found through the XRF analysis are also appreciable. The present work suggests that the incorporation of the rejects into the clay mixture will be a valid route for the ceramic industries to reduce the costs of the ceramic process. Copyright © 2014 Elsevier B.V. All rights reserved.

Utilization of inorganic industrial wastes in producing construction ceramics. Review of Russian experience for the years 2000-2015.

PubMed

Boltakova, N V; Faseeva, G R; Kabirov, R R; Nafikov, R M; Zakharov, Yu A

2017-02-01

This paper analyzes the significant scientific publications worldwide for the last 15years concerning construction ceramics (predominantly brick) made with various inorganic industrial wastes added to the ceramic raw material for the improvement of properties and for eco-friendly disposal. The information gap resulting from the lack of mentions of the Russian publications on this subject in English-language reviews is filled. The paper includes brief summaries of 34 dissertations and 29 patents issued in Russia since 2000. The waste additives described in these summaries are grouped by origin type (mining industry waste, ore enrichment waste, metallurgical waste, sludge, ashes, cullet, large-capacity building wastes and waste from various chemical production processes) with the ceramic mixture compositions, molding and firing conditions, final strength, water absorption and other parameters of the final ceramic samples reported. Russian scientists have expanded the nomenclature of each group of wastes significantly upon addition to the list described in English-language reviews for 2000-2015. References to the recent Russian developments in the field of ecological management in ceramic industry are provided. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effective solidification/stabilisation of mercury-contaminated wastes using zeolites and chemically bonded phosphate ceramics.

PubMed

Zhang, Shaoqing; Zhang, Xinyan; Xiong, Ya; Wang, Guoping; Zheng, Na

2015-02-01

In this study, two kinds of zeolites materials (natural zeolite and thiol-functionalised zeolite) were added to the chemically bonded phosphate ceramic processes to treat mercury-contaminated wastes. Strong promotion effects of zeolites (natural zeolite and thiol-functionalised zeolite) on the stability of mercury in the wastes were obtained and these technologies showed promising advantages toward the traditional Portland cement process, i.e. using Portland cement as a solidification agent and natural or thiol-functionalised zeolite as a stabilisation agent. Not only is a high stabilisation efficiency (lowered the Toxicity Characteristic Leaching Procedure Hg by above 10%) obtained, but also a lower dosage of solidification (for thiol-functionalised zeolite as stabilisation agent, 0.5 g g(-1) and 0.7 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) and stabilisation agents (for natural zeolite as stabilisation agent, 0.35 g g(-1) and 0.4 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) were used compared with the Portland cement process. Treated by thiol-functionalised zeolite and chemically bonded phosphate ceramic under optimum parameters, the waste containing 1500 mg Hg kg(-1) passed the Toxicity Characteristic Leaching Procedure test. Moreover, stabilisation/solidification technology using natural zeolite and chemically bonded phosphate ceramic also passed the Toxicity Characteristic Leaching Procedure test (the mercury waste containing 625 mg Hg kg(-1)). Moreover, the presence of chloride and phosphate did not have a negative effect on the chemically bonded phosphate ceramic/thiol-functionalised zeolite treatment process; thus, showing potential for future application in treatment of 'difficult-to-manage' mercury-contaminated wastes or landfill disposal with high phosphate and chloride content. © The Author(s) 2015.

Subsurface damage and microstructure development in precision microground hard ceramics using magnetorheological finishing spots.

PubMed

Shafrir, Shai N; Lambropoulos, John C; Jacobs, Stephen D

2007-08-01

We demonstrate the use of spots taken with magnetorheological finishing (MRF) for estimating subsurface damage (SSD) depth from deterministic microgrinding for three hard ceramics: aluminum oxynitride (Al(23)O(27)N(5)/ALON), polycrystalline alumina (Al(2)O(3)/PCA), and chemical vapor deposited (CVD) silicon carbide (Si(4)C/SiC). Using various microscopy techniques to characterize the surfaces, we find that the evolution of surface microroughness with the amount of material removed shows two stages. In the first, the damaged layer and SSD induced by microgrinding are removed, and the surface microroughness reaches a low value. Peak-to-valley (p-v) surface microroughness induced from grinding gives a measure of the SSD depth in the first stage. With the removal of additional material, a second stage develops, wherein the interaction of MRF and the material's microstructure is revealed. We study the development of this texture for these hard ceramics with the use of power spectral density to characterize surface features.

Bonded carbon or ceramic fiber composite filter vent for radioactive waste

DOEpatents

Brassell, Gilbert W.; Brugger, Ronald P.

1985-02-19

Carbon bonded carbon fiber composites as well as ceramic or carbon bonded ceramic fiber composites are very useful as filters which can separate particulate matter from gas streams entraining the same. These filters have particular application to the filtering of radioactive particles, e.g., they can act as vents for containers of radioactive waste material.

Research of ceramic matrix for a safe immobilization of radioactive sludge waste

NASA Astrophysics Data System (ADS)

Dorofeeva, Ludmila; Orekhov, Dmitry

2018-03-01

The research and improvement of the existing method for radioactive waste hardening by fixation in a ceramic matrix was carried out. For the samples covered with the sodium silicate and tested after the storage on the air the speed of a radionuclides leaching was determined. The properties of a clay ceramics and the optimum conditions of sintering were defined. The experimental data about the influence of a temperature mode sintering, water quantities, sludge and additives in the samples on their mechanical durability and a water resistance were obtained. The comparative analysis of the conducted research is aimed at improvement of the existing method of the hardening radioactive waste by inclusion in a ceramic matrix and reveals the advantages of the received results over analogs.

Process for immobilizing plutonium into vitreous ceramic waste forms

DOEpatents

Feng, Xiangdong; Einziger, Robert E.

1997-01-01

Disclosed is a method for converting spent nuclear fuel and surplus plutonium into a vitreous ceramic final waste form wherein spent nuclear fuel is bound in a crystalline matrix which is in turn bound within glass.

Process for immobilizing plutonium into vitreous ceramic waste forms

DOEpatents

Feng, X.; Einziger, R.E.

1997-08-12

Disclosed is a method for converting spent nuclear fuel and surplus plutonium into a vitreous ceramic final waste form wherein spent nuclear fuel is bound in a crystalline matrix which is in turn bound within glass.

Process for immobilizing plutonium into vitreous ceramic waste forms

DOEpatents

Feng, X.; Einziger, R.E.

1997-01-28

Disclosed is a method for converting spent nuclear fuel and surplus plutonium into a vitreous ceramic final waste form wherein spent nuclear fuel is bound in a crystalline matrix which is in turn bound within glass.

Method of waste stabilization via chemically bonded phosphate ceramics

DOEpatents

Wagh, Arun S.; Singh, Dileep; Jeong, Seung-Young

1998-01-01

A method for regulating the reaction temperature of a ceramic formulation process is provided comprising supplying a solution containing a monovalent alkali metal; mixing said solution with an oxide powder to create a binder; contacting said binder with bulk material to form a slurry; and allowing the slurry to cure. A highly crystalline waste form is also provided consisting of a binder containing potassium and waste substrate encapsulated by the binder.

The use of waste ceramic tile in cement production

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

Ay, N.; Uenal, M.

In ceramic tile production, because of various reasons, unsold fired products come out. These are waste tiles and only a little part of them are used. Remainings create environmental problems. If these waste tiles are used in cement production, this pollution decreases. In this study, usage of waste tile as pozzolan was studied. Waste tile was added into Portland cement in 25%, 30%, 35%, and 40% weight ratios. Pozzolanic properties of waste tile and setting time, volume stability, particle size, density, specific surface area, and strength of cement including waste tile were investigated. The test results indicated that the wastemore » tiles show pozzolanic properties, and chemical and physical properties of the cement including tile conforms to cement standard up to the addition of 35% waste tile.« less

Method of waste stabilization via chemically bonded phosphate ceramics

DOEpatents

Wagh, A.S.; Singh, D.; Jeong, S.Y.

1998-11-03

A method for regulating the reaction temperature of a ceramic formulation process is provided comprising supplying a solution containing a monovalent alkali metal; mixing said solution with an oxide powder to create a binder; contacting said binder with bulk material to form a slurry; and allowing the slurry to cure. A highly crystalline waste form is also provided consisting of a binder containing potassium and waste substrate encapsulated by the binder. 3 figs.

Treatment of copper industry waste and production of sintered glass-ceramic.

PubMed

Coruh, Semra; Ergun, Osman Nuri; Cheng, Ta-Wui

2006-06-01

Copper waste is iron-rich hazardous waste containing heavy metals such as Cu, Zn, Co, Pb. The results of leaching tests show that the concentration of these elements exceeds the Turkish and EPA regulatory limits. Consequently, this waste cannot be disposed of in its present form and therefore requires treatment to stabilize it or make it inert prior to disposal. Vitrification was selected as the technology for the treatment of the toxic waste under investigation. During the vitrification process significant amounts of the toxic organic and inorganic chemical compounds could be destroyed, and at the same time, the metal species are immobilized as they become an integral part of the glass matrix. The copper flotation waste samples used in this research were obtained from the Black Sea Copper Works of Samsun, Turkey. The samples were vitrified after being mixed with other inorganic waste and materials. The copper flotation waste and their glass-ceramic products were characterized by X-ray analysis (XRD), scanning electron microscopy and by the toxicity characteristic leaching procedure test. The products showed very good chemical durability. The glass-ceramics fabricated at 850 degrees C/2 h have a large application potential especially as construction and building materials.

Glass binder development for a glass-bonded sodalite ceramic waste form

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

Riley, Brian J.; Vienna, John D.; Frank, Steven M.

This paper discusses work to develop Na2O-B2O3-SiO2 glass binders for immobilizing LiCl-KCl eutectic salt waste in a glass-bonded sodalite waste form following electrochemical reprocessing of used metallic nuclear fuel. Here, five new glasses with high Na2O contents were designed to generate waste forms having higher sodalite contents and fewer stress fractures. The structural, mechanical, and thermal properties of the new glasses were measured using variety of analytical techniques. The glasses were then used to produce ceramic waste forms with surrogate salt waste. The materials made using the glasses developed during this study were formulated to generate more sodalite than materialsmore » made with previous baseline glasses used. The coefficients of thermal expansion for the glass phase in the glass-bonded sodalite waste forms made with the new binder glasses were closer to the sodalite phase in the critical temperature region near and below the glass transition temperature. These improvements should result in lower probability of cracking in the full-scale monolithic ceramic waste form, leading to better long-term chemical durability. Additionally, a model generated during this study for predicting softening temperature of silicate binder glasses is presented.« less

Method of waste stabilization with dewatered chemically bonded phosphate ceramics

DOEpatents

Wagh, Arun; Maloney, Martin D.

2010-06-29

A method of stabilizing a waste in a chemically bonded phosphate ceramic (CBPC). The method consists of preparing a slurry including the waste, water, an oxide binder, and a phosphate binder. The slurry is then allowed to cure to a solid, hydrated CBPC matrix. Next, bound water within the solid, hydrated CBPC matrix is removed. Typically, the bound water is removed by applying heat to the cured CBPC matrix. Preferably, the quantity of heat applied to the cured CBPC matrix is sufficient to drive off water bound within the hydrated CBPC matrix, but not to volatalize other non-water components of the matrix, such as metals and radioactive components. Typically, a temperature range of between 100.degree. C.-200.degree. C. will be sufficient. In another embodiment of the invention wherein the waste and water have been mixed prior to the preparation of the slurry, a select amount of water may be evaporated from the waste and water mixture prior to preparation of the slurry. Another aspect of the invention is a direct anyhydrous CBPC fabrication method wherein water is removed from the slurry by heating and mixing the slurry while allowing the slurry to cure. Additional aspects of the invention are ceramic matrix waste forms prepared by the methods disclosed above.

Ceramic Single Phase High-Level Nuclear Waste Forms: Hollandite, Perovskite, and Pyrochlore

NASA Astrophysics Data System (ADS)

Vetter, M.; Wang, J.

2017-12-01

The lack of viable options for the safe, reliable, and long-term storage of nuclear waste is one of the primary roadblocks of nuclear energy's sustainable future. The method being researched is the incorporation and immobilization of harmful radionuclides (Cs, Sr, Actinides, and Lanthanides) into the structure of glasses and ceramics. Borosilicate glasses are the main waste form that is accepted and used by today's nuclear industry, but they aren't the most efficient in terms of waste loading, and durability is still not fully understood. Synroc-phase ceramics (i.e. hollandite, perovskite, pyrochlore, zirconolite) have many attractive qualities that glass waste forms do not: high waste loading, moderate thermal expansion and conductivity, high chemical durability, and high radiation stability. The only downside to ceramics is that they are more complex to process than glass. New compositions can be discovered by using an Artificial Neural Network (ANN) to have more options to optimize the composition, loading for performance by analyzing the non-linear relationships between ionic radii, electronegativity, channel size, and a mineral's ability to incorporate radionuclides into its structure. Cesium can be incorporated into hollandite's A-site, while pyrochlore and perovskite can incorporate actinides and lanthanides into their A-site. The ANN is used to predict new compositions based on hollandite's channel size, as well as the A-O bond distances of pyrochlore and perovskite, and determine which ions can be incorporated. These new compositions will provide more options for more experiments to potentially improve chemical and thermodynamic properties, as well as increased waste loading capabilities.

Magnetic Glass Ceramics by Sintering of Borosilicate Glass and Inorganic Waste.

PubMed

Ponsot, Inès M M M; Pontikes, Yiannis; Baldi, Giovanni; Chinnam, Rama K; Detsch, Rainer; Boccaccini, Aldo R; Bernardo, Enrico

2014-07-31

Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900-1000 °C), whereas glass/slag interactions resulted in the formation of magnetite crystals, providing ferrimagnetism. Such behavior could be exploited for applying the obtained glass ceramics as induction heating plates, according to preliminary tests (showing the rapid heating of selected samples, even above 200 °C). The chemical durability and safety of the obtained glass ceramics were assessed by both leaching tests and cytotoxicity tests.

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.

Use of thin film transistor liquid crystal display (TFT-LCD) waste glass in the production of ceramic tiles.

PubMed

Lin, Kae-Long

2007-09-05

In this study, we employ the following operating conditions: varied pressure (25 kgf/cm(2)), sintering temperature (900-1200 degrees C), sintering time (6h), percentage of thin film transistor liquid crystal display (TFT-LCD) waste glass by weight (0-50%) and temperature rising at a rate of 5 degrees C/min, to fabricate clay tiles. The sintering characteristics of the clay blended with TFT-LCD waste glass tiles are examined to evaluate the feasibility of the reuse of TFT-LCD waste glass. TFT-LCD waste glass contains large amounts of glass. The TCLP leaching concentrations all met the ROC EPAs current regulatory thresholds. The addition of TFT-LCD waste glass to the mixture, increased the apparent weight loss. The incorporation of 50% TFT-LCD waste glass resulted in a significant increase in the porosity ratio of the specimens compared to the porosity ratio of the ceramic tile containing TFT-LCD waste glass. The main constituent in both the clay tile and the clay with TFT-LCD waste glass samples is quartz. Increasing the temperature resulted in an increase in the flexural strength and resistance to abrasion in the tiles. The porosity ratio decreases as shrinkage increases. The relation between the porosity ratio and the hardness of the tiles used in the study is also shown.

Magnetic Glass Ceramics by Sintering of Borosilicate Glass and Inorganic Waste

PubMed Central

Ponsot, Inès M. M. M.; Pontikes, Yiannis; Baldi, Giovanni; Chinnam, Rama K.; Detsch, Rainer; Boccaccini, Aldo R.; Bernardo, Enrico

2014-01-01

Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900–1000 °C), whereas glass/slag interactions resulted in the formation of magnetite crystals, providing ferrimagnetism. Such behavior could be exploited for applying the obtained glass ceramics as induction heating plates, according to preliminary tests (showing the rapid heating of selected samples, even above 200 °C). The chemical durability and safety of the obtained glass ceramics were assessed by both leaching tests and cytotoxicity tests. PMID:28788146

Alternative High-Performance Ceramic Waste Forms

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

Sundaram, S. K.

This final report (M5NU-12-NY-AU # 0202-0410) summarizes the results of the project titled “Alternative High-Performance Ceramic Waste Forms,” funded in FY12 by the Nuclear Energy University Program (NEUP Project # 12-3809) being led by Alfred University in collaboration with Savannah River National Laboratory (SRNL). The overall focus of the project is to advance fundamental understanding of crystalline ceramic waste forms and to demonstrate their viability as alternative waste forms to borosilicate glasses. We processed single- and multiphase hollandite waste forms based on simulated waste streams compositions provided by SRNL based on the advanced fuel cycle initiative (AFCI) aqueous separation process developed in the Fuel Cycle Research and Development (FCR&D). For multiphase simulated waste forms, oxide and carbonate precursors were mixed together via ball milling with deionized water using zirconia media in a polyethylene jar for 2 h. The slurry was dried overnight and then separated from the media. The blended powders were then subjected to melting or spark plasma sintering (SPS) processes. Microstructural evolution and phase assemblages of these samples were studied using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion analysis of x-rays (EDAX), wavelength dispersive spectrometry (WDS), transmission electron spectroscopy (TEM), selective area x-ray diffraction (SAXD), and electron backscatter diffraction (EBSD). These results showed that the processing methods have significant effect on the microstructure and thus the performance of these waste forms. The Ce substitution into zirconolite and pyrochlore materials was investigated using a combination of experimental (in situ XRD and x-ray absorption near edge structure (XANES)) and modeling techniques to study these single phases independently. In zirconolite materials, a transition from the 2M to the 4M polymorph was observed with increasing Ce content. The resulting

Ultrafine Ceramic Grains Embedded in Metallic Glass Matrix: Achieving Superior Wear Resistance via Increase in Both Hardness and Toughness.

PubMed

Yang, Lina; Wen, Mao; Dai, Xuan; Cheng, Gang; Zhang, Kan

2018-05-09

As structural materials, crystalline or metallic glass materials have attracted scientific and practical interests. However, some mechanisms involving critical size and shear bands have adverse effects on their mechanical properties. Here, we counter these two effects by introducing a special structure with ultrafine ceramic grains (with a diameter of ∼2.0 nm) embedded into a metallic glass matrix, wherein the grains are mainly composed of a Ta-W-N solid solution structure in nature, surrounded by a W-based amorphous matrix that contains Ta and N atoms. Such a structure is in situ formed during preparation, which combines the merits of both phases to achieve simultaneous increase in hardness and toughness relative to references (pure TaN and W) and thus superior wear resistance. Even more remarkable, a favorable variation of increased hardness but reduced elasticity modulus can be induced by this structure. Intrinsically, ultrafine ceramic grains (free of dislocations), embedded in the metallic glass matrix, could prevent shear band propagation within the glass matrix and further improve the hardness of the matrix material. In return, such glass matrix allows for stiffness neutralization and structural relaxation to reduce the elasticity modulus of ceramic grains. This study will offer a new guidance to fabricate ultrahigh-performance metal-based composites.

SCALE UP OF CERAMIC WASTE FORMS FOR THE EBR-II SPENT FUEL TREATMENT PROCESS

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

Matthew C. Morrison; Kenneth J. Bateman; Michael F. Simpson

2010-11-01

ABSTRACT SCALE UP OF CERAMIC WASTE FORMS FOR THE EBR-II SPENT FUEL TREATMENT PROCESS Matthew C. Morrison, Kenneth J. Bateman, Michael F. Simpson Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 The ceramic waste process is the intended method for disposing of waste salt electrolyte, which contains fission products from the fuel-processing electrorefiners (ER) at the INL. When mixed and processed with other materials, the waste salt can be stored in a durable ceramic waste form (CWF). The development of the CWF has recently progressed from small-scale testing and characterization to full-scale implementation and experimentation using surrogate materialsmore » in lieu of the ER electrolyte. Two full-scale (378 kg and 383 kg) CWF test runs have been successfully completed with final densities of 2.2 g/cm3 and 2.1 g/cm3, respectively. The purpose of the first CWF was to establish material preparation parameters. The emphasis of the second pre-qualification test run was to evaluate a preliminary multi-section CWF container design. Other considerations were to finalize material preparation parameters, measure the material height as it consolidates in the furnace, and identify when cracking occurs during the CWF cooldown process.« less

Zirconia ceramics for excess weapons plutonium waste

NASA Astrophysics Data System (ADS)

Gong, W. L.; Lutze, W.; Ewing, R. C.

2000-01-01

We synthesized a zirconia (ZrO 2)-based single-phase ceramic containing simulated excess weapons plutonium waste. ZrO 2 has large solubility for other metallic oxides. More than 20 binary systems A xO y-ZrO 2 have been reported in the literature, including PuO 2, rare-earth oxides, and oxides of metals contained in weapons plutonium wastes. We show that significant amounts of gadolinium (neutron absorber) and yttrium (additional stabilizer of the cubic modification) can be dissolved in ZrO 2, together with plutonium (simulated by Ce 4+, U 4+ or Th 4+) and impurities (e.g., Ca, Mg, Fe, Si). Sol-gel and powder methods were applied to make homogeneous, single-phase zirconia solid solutions. Pu waste impurities were completely dissolved in the solid solutions. In contrast to other phases, e.g., zirconolite and pyrochlore, zirconia is extremely radiation resistant and does not undergo amorphization. Baddeleyite (ZrO 2) is suggested as the natural analogue to study long-term radiation resistance and chemical durability of zirconia-based waste forms.

Preparation, Microstructure and Performance of Nanoscale Ceramics Reinforced Hard Composite Coating

NASA Astrophysics Data System (ADS)

Li, Peng

2014-11-01

This paper is based on the dry sliding wear of Stellite SF12-B4C-TiN-Mo composite coating deposited on a pure Ti using a laser cladding technique, the parameters of which provide almost crack-free composites with low porosity. To the best of our knowledge, it is the first time that Stellite SF12-B4C-TiN-Mo mixed powders are deposited as the hard composites by a laser cladding technique. Scanning electron microscope images indicate that the nanoscale particles are produced in such coating. The fact that due to the sufficiently rapid heating and cooling rates of the laser cladding technique, the ceramics, such as TiC or TiB2 did not have enough time to grow up, resulting in the formation of the nanoscale particles. Compared with a pure Ti substrate, the increments of the micro-hardness and wear resistance are obtained for such composite coating.

Unirradiated testing of the demonstration-scale ceramic waste form at ANL-West

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

Goff, K.M.; Simpson, M.F.; Bateman, K.J.

1997-12-01

The ceramic waste form is being developed by Argonne National Laboratory (ANL) as part of the demonstration of the electrometallurgical treatment of spent nuclear fuel for disposal. The alkali, alkaline earth, halide, and rare earth fission products are stabilized in zeolite, which is combined with glass and processed in a hot isostatic press (HIP) to form a ceramic composite. The transuranics, including plutonium, are also stabilized in this high-level waste. Most of the laboratory-scale development work is performed in the Chemical Technology Division of ANL in Illinois. At ANL-West in Idaho, this technology is being demonstrated on an engineering scalemore » before implementation with irradiated materials in a remote environment.« less

Recycling of Malaysia's electric arc furnace (EAF) slag waste into heavy-duty green ceramic tile.

PubMed

Teo, Pao-Ter; Anasyida, Abu Seman; Basu, Projjal; Nurulakmal, Mohd Sharif

2014-12-01

Recently, various solid wastes from industry such as glass waste, fly ash, sewage sludge and slag have been recycled into various value-added products such as ceramic tile. The conventional solutions of dumping the wastes in landfills or incineration, including in Malaysia are getting obsolete as the annual huge amount of the solid wastes would boost-up disposal cost and may cause permanent damage to the flora and fauna. This recent waste recycling approach is much better and greener as it can resolve problems associated with over-limit storage of industrial wastes and reduce exploration of natural resources for ceramic tile to continuously sustain the nature. Therefore, in this project, an attempt was made to recycle electric arc furnace (EAF) slag waste, obtained from Malaysia's steel making industry, into ceramic tile via conventional powder compaction method. The research work was divided into two stages. The first stage was to evaluate the suitability of EAF slag in ceramic tile by varying weight percentage of EAF slag (40 wt.%, 50 wt.% and 60 wt.%) and ball clay (40 wt.%, 50 wt.% and 60 wt.%), with no addition of silica and potash feldspar. In the second stage, the weight percentage of EAF slag was fixed at 40 wt.% and the percentage of ball clay (30 wt.% and 40 wt.%), feldspar (10 wt.% and 20 wt.%) and silica (10 wt.% and 20 wt.%) added was varied accordingly. Results obtained show that as weight percentage of EAF slag increased up to 60 wt.%, the percentage of apparent porosity and water absorption also rose, with a reduction in tile flexural strength and increased porosity. On the other hand, limiting the weight percentage of EAF slag to 40 wt.% while increasing the weight percentage of ball clay led to a higher total percentage of anorthite and wollastonite minerals, resulting in higher flexural strength. It was found that introduction of silica and feldspar further improved the flexural strength due to optimization of densification process. The highest

A view of microstructure with technological behavior of waste incorporated ceramic bricks.

PubMed

Nirmala, G; Viruthagiri, G

2015-01-25

Production of ceramic bricks from mixtures of ceramic industry wastes (up to 50 wt%) from the area of Vriddhachalam, Cuddalore district, Tamilnadu, India and kaolinitic clay from Thiruvananthapuram district, Kerala were investigated. The firing behavior of the ceramic mixtures was studied by determining their changes in mineralogy and basic ceramic properties such as water absorption, porosity, compressive strength and firing shrinkage at temperatures ranging from 900 to 1200 °C in short firing cycles. The effect of the rejects addition gradually up to 50 wt% was analyzed with the variation of temperature on the mechanical properties and microstructure of the bricks. The highest compressive strength and lowest water absorption is observed for the sample with 40% rejects at 1100 °C which is supported by the results of SEM analysis. The resulting ceramic bricks exhibit features that suggest possibilities of using the ceramic rejects in the conventional brick making methods. Copyright © 2014 Elsevier B.V. All rights reserved.

[Influence of liquid ceramic additive on binding of heavy metal during the vitrification of fly ash from municipal solid waste incinerator].

PubMed

Li, Run-dong; Nie, Yong-feng; Li, Ai-min; Wang, Lei; Chi, Yong; Cen, Ke-fa

2004-09-01

Vitrification process can effectively control the leachability of heavy metals in fly ash generated from municipal solid waste incinerator (MWSI). The use of liquid ceramic (LC) additive as a heavy metal chemical stabilization agent was evaluated for MSWI fly ash. The residuals of chromium, lead and zinc in slag increase by different degree with liquid ceramic additive at 1400 degrees C, while those of cadmium and copper decreases. The migrating characteristic of nickel is hardly affected by the additive less than 10%. The volatilization of Cr and Zn occurs after 61 minute with 10% addition of LC, and the binding efficiency of Cr decreases with increasing of melting temperature. The results indicate that the binding efficiency of heavy metals was affected greatly by LC additive and showed significant differences according to type of heavy metal during melting process. The short melting time (no longer than 33 min) is useful to obtain high binding efficiency of heavy metals.

Biofunctionalized Ceramic with Self-Assembled Networks of Nanochannels

PubMed Central

Jang, Hae Lin; Lee, Keunho; Kang, Chan Soon; Lee, Hye Kyoung; Ahn, Hyo-Yong; Jeong, Hui-Yun; Park, Sunghak; Kim, Seul Cham; Jin, Kyoungsuk; Park, Jimin; Yang, Tae-Youl; Kim, Jin Hong; Shin, Seon Ae; Han, Heung Nam; Oh, Kyu Hwan; Lee, Ho-Young; Lim, Jun; Hong, Kug Sun; Snead, Malcolm L.; Xu, Jimmy; Nam, Ki Tae

2015-01-01

Nature designs circulatory systems with hierarchically organized networks of gradually tapered channels ranging from micrometer to nanometer in diameter. In most hard tissues in biological systems, fluid, gasses, nutrients and wastes are constantly exchanged through such networks. Here, we developed a biologically-inspired, hierarchically-organized structure in ceramic to achieve effective permeation with minimum void region, using fabrication methods that create a long-range, highly-interconnected nanochannel system in a ceramic biomaterial. This design of a synthetic model-material was implemented through a novel pressurized sintering process formulated to induce a gradual tapering in channel diameter based on pressure-dependent polymer agglomeration. The resulting system allows long range, efficient transport of fluid and nutrients into sites and interfaces that conventional fluid conduction cannot reach without external force. We demonstrate the ability of mammalian bone-forming cells placed at the distal transport termination of the nanochannel system to proliferate in a manner dependent solely upon the supply of media by the self-powering nanochannels. This approach mimics the significant contribution that nanochannel transport plays in maintaining living hard tissues by providing nutrient supply that facilitates cell growth and differentiation, and thereby makes the ceramic composite ‘alive’. PMID:25827409

Fluorescent Lamp Glass Waste Incorporation into Clay Ceramic: A Perfect Solution

NASA Astrophysics Data System (ADS)

Morais, Alline Sardinha Cordeiro; Vieira, Carlos Maurício Fontes; Rodriguez, Rubén Jesus Sanchez; Monteiro, Sergio Neves; Candido, Veronica Scarpini; Ferreira, Carlos Luiz

2016-09-01

The mandatory use of fluorescent lamps as part of a Brazilian energy-saving program generates a huge number of spent fluorescent lamps (SFLs). After operational life, SFLs cannot be disposed as common garbage owing to mercury and lead contamination. Recycling methods separate contaminated glass tubes and promote cleaning for reuse. In this work, glass from decontaminated SFLs was incorporated into clay ceramics, not only as an environmental solution for such glass wastes and clay mining reduction but also due to technical and economical advantages. Up to 30 wt.% of incorporation, a significant improvement in fired ceramic flexural strength and a decrease in water absorption was observed. A prospective analysis showed clay ceramic incorporation as an environmentally correct and technical alternative for recycling the enormous amount of SFLs disposed of in Brazil. This could also be a solution for other world clay ceramic producers, such as US, China and some European countries.

Effect of electrical and mechanical poling history on domain orientation and piezoelectric properties of soft and hard PZT ceramics

NASA Astrophysics Data System (ADS)

Marsilius, Mie; Granzow, Torsten; Jones, Jacob L.

2011-02-01

The superior piezoelectric properties of all polycrystalline ferroelectrics are based on the extent of non-180° domain wall motion under electrical and mechanical poling loads. To distinguish between 180° and non-180° domain wall motion in a soft-doped and a hard-doped lead zirconate titanate (PZT) ceramic, domain texture measurements were performed using x-ray and neutron diffraction after different loading procedures. Comparing the results to measurements of the remanent strain and piezoelectric coefficient allowed the differentiation between different microstructural contributions to the macroscopic parameters. Both types of ceramic showed similar behavior under electric field, but the hard-doped material was more susceptible to mechanical load. A considerable fraction of the piezoelectric coefficient originated from poling by the preferred orientation of 180° domains.

FY16 Annual Accomplishments - Waste Form Development and Performance: Evaluation Of Ceramic Waste Forms - Comparison Of Hot Isostatic Pressed And Melt Processed Fabrication Methods

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

Amoroso, J.; Dandeneau, C.

FY16 efforts were focused on direct comparison of multi-phase ceramic waste forms produced via melt processing and HIP methods. Based on promising waste form compositions previously devised at SRNL, simulant material was prepared at SRNL and a portion was sent to the Australian Nuclear Science and Technology Organization (ANSTO) for HIP treatments, while the remainder of the material was melt processed at SRNL. The microstructure, phase formation, elemental speciation, and leach behavior, and radiation stability of the fabricated ceramics was performed. In addition, melt-processed ceramics designed with different fractions of hollandite, zirconolite, perovskite, and pyrochlore phases were investigated. for performancemore » and properties.« less

Decomposition Mechanism and Decomposition Promoting Factors of Waste Hard Metal for Zinc Decomposition Process (ZDP)

NASA Astrophysics Data System (ADS)

Pee, J. H.; Kim, Y. J.; Kim, J. Y.; Seong, N. E.; Cho, W. S.; Kim, K. J.

2011-10-01

Decomposition promoting factors and decomposition mechanism in the zinc decomposition process of waste hard metals which are composed mostly of tungsten carbide and cobalt were evaluated. Zinc volatility amount was suppressed and zinc steam pressure was produced in the reaction graphite crucible inside an electric furnace for ZDP. Reaction was done for 2 hrs at 650 °C, which 100 % decomposed the waste hard metals that were over 30 mm thick. As for the separation-decomposition of waste hard metals, zinc melted alloy formed a liquid composed of a mixture of γ-β1 phase from the cobalt binder layer (reaction interface). The volume of reacted zone was expanded and the waste hard metal layer was decomposed-separated horizontally from the hard metal. Zinc used in the ZDP process was almost completely removed-collected by decantation and volatilization-collection process at 1000 °C. The small amount of zinc remaining in the tungsten carbide-cobalt powder which was completely decomposed was fully removed by using phosphate solution which had a slow cobalt dissolution speed.

Final Project Report CFA-14-6357: A New Paradigm for Understanding Multiphase Ceramic Waste Form Performance

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

Brinkman, Kyle; Bordia, Rajendra; Reifsnider, Kenneth

This project fabricated model multiphase ceramic waste forms with processing-controlled microstructures followed by advanced characterization with synchrotron and electron microscopy-based 3D tomography to provide elemental and chemical state-specific information resulting in compositional phase maps of ceramic composites. Details of 3D microstructural features were incorporated into computer-based simulations using durability data for individual constituent phases as inputs in order to predict the performance of multiphase waste forms with varying microstructure and phase connectivity.

Analysis of waste coal from the enterprises of Kemerovo region as raw materials for production of ceramic materials

NASA Astrophysics Data System (ADS)

Stolboushkin, A. Yu; Akst, D. V.; Fomina, O. A.; Ivanov, A. I.; Syromyasov, V. A.

2017-09-01

The analysis of waste coal from mining enterprises of Kemerovo region as raw materials for production of building ceramics is given. The results of studies of material, chemical and mineralogical compositions of waste coal from Abashevskaya processing plant (Novokuznetsk) are presented. It was established that the chemical composition of waste coal refers to aluminosilicate raw materials with a high content of alumina and coloring oxides, the residual carbon content in the wastes is 12-25 %. According to the granulometric composition the waste coal is basically a sandy-dusty fraction with a small amount of clay particles (1-3 %). Additional grinding of coal waste and the introduction of a clay additive in an amount of up to 30 % are recommended. The results of the study of the mineral composition of waste coal are presented. Clay minerals are represented in the descending order by hydromuscovite, montmorillonite and kaolinite, minerals-impurities consist of quartz, feldspar fine-dispersed carbonates. The results of the investigation of ceramic-technological properties of waste coal, which belong to the group of moderately plastic low-melting raw materials, are given. As a result of a comprehensive study it was been established that with chemical, granulometric and mineralogical compositions waste coal with the reduced residual carbon can be used in the production of ceramic bricks.

Development of iron phosphate ceramic waste form to immobilize radioactive waste solution

NASA Astrophysics Data System (ADS)

Choi, Jongkwon; Um, Wooyong; Choung, Sungwook

2014-09-01

The objective of this research was to develop an iron phosphate ceramic (IPC) waste form using converter slag obtained as a by-product of the steel industry as a source of iron instead of conventional iron oxide. Both synthetic off-gas scrubber solution containing technetium-99 (or Re as a surrogate) and LiCl-KCl eutectic salt, a final waste solution from pyrochemical processing of spent nuclear fuel, were used as radioactive waste streams. The IPC waste form was characterized for compressive strength, reduction capacity, chemical durability, and contaminant leachability. Compressive strengths of the IPC waste form prepared with different types of waste solutions were 16 MPa and 19 MPa for LiCl-KCl eutectic salt and the off-gas scrubber simulant, respectively, which meet the minimum compressive strength of 3.45 MPa (500 psi) for waste forms to be accepted into the radioactive waste repository. The reduction capacity of converter slag, a main dry ingredient used to prepare the IPC waste form, was 4136 meq/kg by the Ce(IV) method, which is much higher than those of the conventional Fe oxides used for the IPC waste form and the blast furnace slag materials. Average leachability indexes of Tc, Li, and K for the IPC waste form were higher than 6.0, and the IPC waste form demonstrated stable durability even after 63-day leaching. In addition, the Toxicity Characteristic Leach Procedure measurements of converter slag and the IPC waste form with LiCl-KCl eutectic salt met the universal treatment standard of the leachability limit for metals regulated by the Resource Conservation and Recovery Act. This study confirms the possibility of development of the IPC waste form using converter slag, showing its immobilization capability for radionuclides in both LiCl-KCl eutectic salt and off-gas scrubber solutions with significant cost savings.

Development of iron phosphate ceramic waste form to immobilize radioactive waste solution

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

Choi, Jongkwon; Um, Wooyong; Choung, Sungwook

The objective of this research was to develop an iron phosphate ceramic (IPC) waste form using converter slag obtained as a by-product of the steel industry as a source of iron instead of conventional iron oxide. Both synthetic off-gas scrubber solution containing technetium-99 (or Re as a surrogate) and LiCl-KCl eutectic salt, a final waste solution from pyrochemical processing of spent nuclear fuel, were used as radioactive waste streams. The IPC waste form was characterized for compressive strength, reduction capacity, chemical durability, and contaminant leachability. Compressive strengths of the IPC waste form prepared with different types of waste solutions weremore » 16 MPa and 19 MPa for LiCl-KCl eutectic salt and the off-gas scrubber simulant, respectively, which meet the minimum compressive strength of 3.45 MPa (500 psi) for waste forms to be accepted into the radioactive waste repository. The reduction capacity of converter slag, a main dry ingredient used to prepare the IPC waste form, was 4,136 meq/kg by the Ce(IV) method, which is much higher than those of the conventional Fe oxides used for the IPC waste form and the blast furnace slag materials. Average leachability indexes of Tc, Li, and K for the IPC waste form were higher than 6.0, and the IPC waste form demonstrated stable durability even after 63-day leaching. In addition, the Toxicity Characteristic Leach Procedure measurements of converter slag and the IPC waste form with LiCl-KCl eutectic salt met the universal treatment standard of the leachability limit for metals regulated by the Resource Conservation and Recovery Act. This study confirms the possibility of development of the IPC waste form using converter slag, showing its immobilization capability for radionuclides in both LiCl-KCl eutectic salt and off-gas scrubber solutions with significant cost savings.« less

Properties of ceramics prepared using dry discharged waste to energy bottom ash dust.

PubMed

Bourtsalas, Athanasios; Vandeperre, Luc; Grimes, Sue; Themelis, Nicolas; Koralewska, Ralf; Cheeseman, Chris

2015-09-01

The fine dust of incinerator bottom ash generated from dry discharge systems can be transformed into an inert material suitable for the production of hard, dense ceramics. Processing involves the addition of glass, ball milling and calcining to remove volatile components from the incinerator bottom ash. This transforms the major crystalline phases present in fine incinerator bottom ash dust from quartz (SiO(2)), calcite (CaCO(3)), gehlenite (Ca(2)Al(2)SiO(7)) and hematite (Fe(2)O(3)), to the pyroxene group minerals diopside (CaMgSi(2)O(6)), clinoenstatite (MgSi(2)O(6)), wollastonite (CaSiO(3)) together with some albite (NaAlSi(3)O(8)) and andradite (Ca(3)Fe(2)Si(3)O(12)). Processed powders show minimal leaching and can be pressed and sintered to form dense (>2.5 g cm(-3)), hard ceramics that exhibit low firing shrinkage (<7%) and zero water absorption. The research demonstrates the potential to beneficially up-cycle the fine incinerator bottom ash dust from dry discharge technology into a raw material suitable for the production of ceramic tiles that have potential for use in a range of industrial applications. © The Author(s) 2015.

[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.

Y-TZP ceramic processing from coprecipitated powders: a comparative study with three commercial dental ceramics.

PubMed

Lazar, Dolores R R; Bottino, Marco C; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H A

2008-12-01

(1) To synthesize 3mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. A coprecipitation route was used to synthesize a 3mol% yttria-stabilized zirconia ceramic processed by uniaxial compaction and pressureless sintering. Commercially available alumina or alumina/zirconia ceramics, namely Procera AllCeram (PA), In-Ceram Zirconia Block (CAZ) and In-Ceram Zirconia (IZ) were chosen for comparison. All specimens (6mmx5mmx5mm) were polished and ultrasonically cleaned. Qualitative phase analysis was performed by XRD and apparent densities were measured on the basis of Archimedes principle. Ceramics were also characterized using SEM, TEM and EDS. The hardness measurements were made employing Vickers hardness test. Fracture toughness (K(IC)) was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test (alpha=0.05). ANOVA revealed that the Vickers hardness (p<0.0001) and fracture toughness (p<0.0001) were affected by the ceramic materials composition. It was confirmed that the PA ceramic was constituted of a rhombohedral alumina matrix, so-called alpha-alumina. Both CAZ and IZ ceramics presented tetragonal zirconia and alpha-alumina mixture of phases. The SEM/EDS analysis confirmed the presence of aluminum in PA ceramic. In the IZ and CAZ ceramics aluminum, zirconium and cerium in grains involved by a second phase containing aluminum, silicon and lanthanum were identified. PA showed significantly higher mean Vickers hardness values (H(V)) (18.4+/-0.5GPa) compared to vitreous CAZ (10.3+/-0.2GPa) and IZ (10.6+/-0.4GPa) ceramics. Experimental Y-TZP showed significantly lower results than that of the other monophased ceramic (PA) (p<0.05) but it showed significantly higher fracture toughness (6.0+/-0.2MPam(1/2)) values when compared to the

Three-dimensional mapping of crystalline ceramic waste form materials

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

Cocco, Alex P.; DeGostin, Matthew B.; Wrubel, Jacob A.

Here, we demonstrate the use of synchrotron-based, transmission X-ray microscopy (TXM) and scanning electron microscopy to image the 3-D morphologies and spatial distributions of Ga-doped phases within model, single- and two-phase waste form material systems. Gallium doping levels consistent with those commonly used for nuclear waste immobilization (e.g., Ba 1.04Cs 0.24Ga 2.32Ti 5.68O 16) could be readily imaged. This analysis suggests that a minority phase with different stoichiometry/composition from the primary hollandite phase can be formed by the solid-state ceramic processing route with varying morphology (globular vs. cylindrical) as a function of Cs content. Our results represent a crucial stepmore » in developing the tools necessary to gain an improved understanding of the microstructural and chemical properties of waste form materials that influence their resistance to aqueous corrosion. This understanding will aid in the future design of higher durability waste form materials.« less

Three-dimensional mapping of crystalline ceramic waste form materials

DOE PAGES

Cocco, Alex P.; DeGostin, Matthew B.; Wrubel, Jacob A.; ...

2017-04-21

Here, we demonstrate the use of synchrotron-based, transmission X-ray microscopy (TXM) and scanning electron microscopy to image the 3-D morphologies and spatial distributions of Ga-doped phases within model, single- and two-phase waste form material systems. Gallium doping levels consistent with those commonly used for nuclear waste immobilization (e.g., Ba 1.04Cs 0.24Ga 2.32Ti 5.68O 16) could be readily imaged. This analysis suggests that a minority phase with different stoichiometry/composition from the primary hollandite phase can be formed by the solid-state ceramic processing route with varying morphology (globular vs. cylindrical) as a function of Cs content. Our results represent a crucial stepmore » in developing the tools necessary to gain an improved understanding of the microstructural and chemical properties of waste form materials that influence their resistance to aqueous corrosion. This understanding will aid in the future design of higher durability waste form materials.« less

Production of glass-ceramics from sewage sludge and waste glass

NASA Astrophysics Data System (ADS)

Rozenstrauha, I.; Sosins, G.; Petersone, L.; Krage, L.; Drille, M.; Filipenkov, V.

2011-12-01

In the present study for recycling of sewage sludge and waste glass from JSC "Valmieras stikla skiedra" treatment of them to the dense glass-ceramic composite material using powder technology is estimated. The physical-chemical properties of composite materials were identified - density 2.19 g/cm3, lowest water absorption of 2.5% and lowest porosity of 5% for the samples obtained in the temperature range of sintering 1120 - 1140 °C. Regarding mineralogical composition of glass-ceramics the following crystalline phases were identified by XRD analysis: quartz (SiO2), anorthite (CaAl2Si2O8) and hematite (Fe2O3), which could ensure the high density of materials and improve the mechanical properties of material - compressive strength up to 60.31±5.09 - 52.67±19.18 MPa. The physical-chemical properties of novel materials corresponds to dense glass-ceramics composite which eventually could be used as a building material, e.g. for floor covering, road pavement, exterior tiles etc.

DSC and TG Analysis of a Blended Binder Based on Waste Ceramic Powder and Portland Cement

NASA Astrophysics Data System (ADS)

Pavlík, Zbyšek; Trník, Anton; Kulovaná, Tereza; Scheinherrová, Lenka; Rahhal, Viviana; Irassar, Edgardo; Černý, Robert

2016-03-01

Cement industry belongs to the business sectors characteristic by high energy consumption and high {CO}2 generation. Therefore, any replacement of cement in concrete by waste materials can lead to immediate environmental benefits. In this paper, a possible use of waste ceramic powder in blended binders is studied. At first, the chemical composition of Portland cement and ceramic powder is analyzed using the X-ray fluorescence method. Then, thermal and mechanical characterization of hydrated blended binders containing up to 24 % ceramic is carried out within the time period of 2 days to 28 days. The differential scanning calorimetry and thermogravimetry measurements are performed in the temperature range of 25°C to 1000°C in an argon atmosphere. The measurement of compressive strength is done according to the European standards for cement mortars. The thermal analysis results in the identification of temperature and quantification of enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-hydrates dehydration and portlandite, vaterite and calcite decomposition. The portlandite content is found to decrease with time for all blends which provides the evidence of the pozzolanic activity of ceramic powder even within the limited monitoring time of 28 days. Taking into account the favorable results obtained in the measurement of compressive strength, it can be concluded that the applied waste ceramic powder can be successfully used as a supplementary cementing material to Portland cement in an amount of up to 24 mass%.

Enhancing steel properties through in situ formation of ultrahard ceramic surface

PubMed Central

Pahlevani, Farshid; Kumar, Rahul; Gorjizadeh, Narjes; Hossain, Rumana; Cholake, Sagar T; Privat, Karen; Sahajwalla, Veena

2016-01-01

Abrasion and corrosion resistant steel has attracted considerable interest for industrial application as a means of minimising the costs associated with product/component failures and/or short replacement cycles. These classes of steels contain alloying elements that increase their resistance to abrasion and corrosion. Their benefits, however, currently come at a potentially prohibitive cost; such high performance steel products are both more technically challenging and more expensive to produce. Although these methods have proven effective in improving the performance of more expensive, high-grade steel components, they are not economically viable for relatively low cost steel products. New options are needed. In this study, a complex industrial waste stream has been transformed in situ via precisely controlled high temperature reactions to produce an ultrahard ceramic surface on steel. This innovative ultrahard ceramic surface increases both the hardness and compressive strength of the steel. Furthermore, by modifying the composition of the waste input and the processing parameters, the ceramic surface can be effectively customised to match the intended application of the steel. This economical new approach marries industry demands for more cost-effective, durable steel products with global imperatives to address resource depletion and environmental degradation through the recovery of resources from waste. PMID:27929096

Enhancing steel properties through in situ formation of ultrahard ceramic surface.

PubMed

Pahlevani, Farshid; Kumar, Rahul; Gorjizadeh, Narjes; Hossain, Rumana; Cholake, Sagar T; Privat, Karen; Sahajwalla, Veena

2016-12-08

Abrasion and corrosion resistant steel has attracted considerable interest for industrial application as a means of minimising the costs associated with product/component failures and/or short replacement cycles. These classes of steels contain alloying elements that increase their resistance to abrasion and corrosion. Their benefits, however, currently come at a potentially prohibitive cost; such high performance steel products are both more technically challenging and more expensive to produce. Although these methods have proven effective in improving the performance of more expensive, high-grade steel components, they are not economically viable for relatively low cost steel products. New options are needed. In this study, a complex industrial waste stream has been transformed in situ via precisely controlled high temperature reactions to produce an ultrahard ceramic surface on steel. This innovative ultrahard ceramic surface increases both the hardness and compressive strength of the steel. Furthermore, by modifying the composition of the waste input and the processing parameters, the ceramic surface can be effectively customised to match the intended application of the steel. This economical new approach marries industry demands for more cost-effective, durable steel products with global imperatives to address resource depletion and environmental degradation through the recovery of resources from waste.

A finite difference model used to predict the consolidation of a ceramic waste form produced from the electrometallurgical treatment of spent nuclear fuel.

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

Bateman, K. J.; Capson, D. D.

2004-03-29

Argonne National Laboratory (ANL) has developed a process to immobilize waste salt containing fission products, uranium, and transuranic elements as chlorides in a glass-bonded ceramic waste form. This salt was generated in the electrorefining operation used in the electrometallurgical treatment of spent Experimental Breeder Reactor-II (EBR-II) fuel. The ceramic waste process culminates with an elevated temperature operation. The processing conditions used by the furnace, for demonstration scale and production scale operations, are to be developed at Argonne National Laboratory-West (ANL-West). To assist in selecting the processing conditions of the furnace and to reduce the number of costly experiments, a finitemore » difference model was developed to predict the consolidation of the ceramic waste. The model accurately predicted the heating as well as the bulk density of the ceramic waste form. The methodology used to develop the computer model and a comparison of the analysis to experimental data is presented.« less

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.

An Extended Hardness Limit in Bulk Nanoceramics

DTIC Science & Technology

2014-01-01

spinel as an archetypal hard ceramic, the hardness of this transparent ceramic armor is shown to rigorously follow the Hall–Petch relationship down...as a result of complex phenomena related to an unconven- tionally high ratio of atoms on interfaces, or grain bound- aries, to atoms in the grain

Structure and short time degradation studies of sodium zirconium phosphate ceramics loaded with simulated fast breeder (FBR) waste

NASA Astrophysics Data System (ADS)

Ananthanarayanan, A.; Ambashta, R. D.; Sudarsan, V.; Ajithkumar, T.; Sen, D.; Mazumder, S.; Wattal, P. K.

2017-04-01

Sodium zirconium phosphate (NZP) ceramics have been prepared using conventional sintering and hot isostatic pressing (HIP) routes. The structure of NZP ceramics, prepared using the HIP route, has been compared with conventionally sintered NZP using a combination of X-ray diffraction (XRD) and (31P and 23Na) nuclear magnetic resonance (NMR) spectroscopy techniques. It is observed that NZP with no waste loading is aggressive toward the steel HIP-can during hot isostatic compaction and significant fraction of cations from the steel enter the ceramic material. Waste loaded NZP samples (10 wt% simulated FBR waste) show significantly low can-interaction and primary NZP phase is evident in this material. Upon exposure of can-interacted and waste loaded NZP to boiling water and steam, 31P NMR does not detect any major modifications in the network structure. However, the 23Na NMR spectra indicate migration of Na+ ions from the surface and possible re-crystallization. This is corroborated by Small-Angle Neutron Scattering (SANS) data and Scanning Electron Microscopy (SEM) measurements carried out on these samples.

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives.

PubMed

Jing, Yang; Luo, Jianbin; Yang, Wenyan; Ju, Guoxian

2004-11-01

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the practical application to the drive products. The U-type substrate attached to each side via piezoelectric elements also was simulated by the finite-element method and practically measured by a laser Doppler vibrometer in order to testify the driving mechanics of it. The micro-actuator coupled with two piezoelectric elements featured large displacement of 0.875 microm and high-resonance frequency over 22 kHz. The novel piezoelectric micro-actuators then possess a useful compromise performance to displacement, resonance frequency, and generative force. The results reveal that the new design concept provides a valuable alternative for multilayer piezoelectric micro-actuators.

Subsurface Damage and Microstructure Development in Precision Microground Hard Ceramics Using Magnetorheological Finishing Spots

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

Shafrir, S.N.; Lambropoulos, J.C.; Jacobs, S.D.

2007-08-01

We demonstrate the use of spots taken with magnetorheological finishing (MRF) for estimating subsurface damage (SSD) depth from deterministic microgrinding for three hard ceramics: aluminum oxynitride (Al23O27N5/ALON), polycrystalline alumina (AL2O3/PCA), and chemical vapor deposited (CVD) silicon carbide (Si4C/SiC). Using various microscopy techniques to characterize the surfaces, we find that the evolution of surface microroughness with the amount of material removed shows two stages. In the first, the damaged layer and SSD induced by microgrinding are removed, and the surface roughness reaches a low value. Peak-to-valley (p-v) surface microroughness induced from grinding gives a measure of the SSD depth in themore » first stage. With the removal of additional material, a second stage develops, wherein the interaction of MRF and the material's microstructure is revealed. We study the development of this texture for these har ceramics with the use of power spectral density to characterize surface features.« less

Review of palm oil fuel ash and ceramic waste in the production of concrete

NASA Astrophysics Data System (ADS)

Natasya Mazenan, Puteri; Sheikh Khalid, Faisal; Shahidan, Shahiron; Shamsuddin, Shamrul-mar

2017-11-01

High demand for cement in the concrete production has been increased which become the problems in the industry. Thus, this problem will increase the production cost of construction material and the demand for affordable houses. Moreover, the production of Portland cement leads to the release of a significant amount of CO2 and other gases leading to the effect on global warming. The need for a sustainable and green construction building material is required in the construction industry. Hence, this paper presents utilization of palm oil fuel ash and ceramic waste as partial cement replacement in the production of concrete. Using both of this waste in the concrete production would benefit in many ways. It is able to save cost and energy other than protecting the environment. In short, 20% usage of palm oil fuel ash and 30% replacement of ceramic waste as cement replacement show the acceptable and satisfactory strength of concrete.

Ceramic Borehole Seals for Nuclear Waste Disposal Applications

NASA Astrophysics Data System (ADS)

Lowry, B.; Coates, K.; Wohletz, K.; Dunn, S.; Patera, E.; Duguid, A.; Arnold, B.; Zyvoloski, G.; Groven, L.; Kuramyssova, K.

2015-12-01

Sealing plugs are critical features of the deep borehole system design. They serve as structural platforms to bear the weight of the backfill column, and as seals through their low fluid permeability and bond to the borehole or casing wall. High hydrostatic and lithostatic pressures, high mineral content water, and elevated temperature due to the waste packages and geothermal gradient challenge the long term performance of seal materials. Deep borehole nuclear waste disposal faces the added requirement of assuring performance for thousands of years in large boreholes, requiring very long term chemical and physical stability. A high performance plug system is being developed which capitalizes on the energy of solid phase reactions to form a ceramic plug in-situ. Thermites are a family of self-oxidized metal/oxide reactions with very high energy content and the ability to react under water. When combined with engineered additives the product exhibits attractive structural, sealing, and corrosion properties. In the initial phase of this research, exploratory and scaled tests demonstrated formulations that achieved controlled, fine grained, homogeneous, net shape plugs composed predominantly of ceramic material. Laboratory experiments produced plug cores with confined fluid permeability as low as 100 mDarcy, compressive strength as high as 70 MPa (three times the strength of conventional well cement), with the inherent corrosion resistance and service temperature of ceramic matrices. Numerical thermal and thermal/structural analyses predicted the in-situ thermal performance of the reacted plugs, showing that they cooled to ambient temperature (and design strength) within 24 to 48 hours. The current development effort is refining the reactant formulations to achieve desired performance characteristics, developing the system design and emplacement processes to be compatible with conventional well service practices, and understanding the thermal, fluid, and structural

Research Update: Hard carbon with closed pores from pectin-free apple pomace waste for Na-ion batteries

NASA Astrophysics Data System (ADS)

Dou, Xinwei; Geng, Chenxi; Buchholz, Daniel; Passerini, Stefano

2018-04-01

Herein, we report a hard carbon derived from industrial bio-waste, i.e., pectin-free apple pomace. The structural, morphological, and electrochemical properties of the hard carbon are reported. The impact of the bio-waste on the closed porosity is discussed, providing valuable insights into the sodium storage mechanism in hard carbons. Most importantly, the hard carbon delivers good electrochemical performance, high specific capacities of 285 mAh g-1, and a very good capacity retention of 96% after 230 cycles at 0.1 C.

Qualitative Assessment of Wear Resistance and Surface Hardness of Different Commercially Available Dental Porcelain: An in vitro Study.

PubMed

Singh, Abhishek; Nagpal, Abhishek; Pawah, Salil; Pathak, Chetan; Issar, Gaurav; Sharma, Pankaj

2016-09-01

In an attempt to minimize wear damage to the enamel of antagonist teeth, new low and medium fusing ceramic materials have been developed. Manufacturers usually claim that these ceramics are wear-friendly because of their lower hardness, lower concentrations of crystal phase, and smaller crystal sizes. This study aimed to quantitatively analyze the wear strength of various commercially available dental porcelain with tooth enamel as well as the surface hardness of these dental porcelain. The basic model was designed as a pin on plate arrangement. The tooth specimens were mounted on the stylus which was centered on the ceramic specimen in a wear testing machine. The dental ceramic specimen was centered in the metal die. A load of 40 N was applied at a rate of 80 cycles/minute for 15 minutes. In the current study, mean wear depth (Ra) value, volumetric loss, and surface hardness were obtained by standard quantification method and were statistically evaluated. Ceramco-3 was reported to be most abrasive for enamel; however, Duceram love significantly more abraded itself than the other two, Ceramco-3 and Vita Alpha, and generated the lowest loss of enamel. Also, same abrasive type of wear was revealed for all three variants of tested ceramics. Ceramco-3 was the most abrasive for enamel, while surface roughness (mean wear depth) of Duceram love was maximum and for Ceramco-3 it was minimum. The value of surface roughness for Vita Alpha was in between Duceram love and Ceramco-3. Nonetheless, the mean surface hardness of Duceram love was found to be least and maximum for Vita Alpha. In situations of dental wear and wasting tooth disease (Attrition/Abrasion), Duceram can be applied in lieu of Ceramco-3 so as to prevent worsening of existing dentition. However, in younger patients Vita Alpha would offer maximum durability due to its greater surface hardness.

Preliminary Technology Maturation Plan for Immobilization of High-Level Waste in Glass Ceramics

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

Vienna, John D.; Crum, Jarrod V.; Sevigny, Gary J.

2012-09-30

A technology maturation plan (TMP) was developed for immobilization of high-level waste (HLW) raffinate in a glass ceramics waste form using a cold-crucible induction melter (CCIM). The TMP was prepared by the following process: 1) define the reference process and boundaries of the technology being matured, 2) evaluate the technology elements and identify the critical technology elements (CTE), 3) identify the technology readiness level (TRL) of each of the CTE’s using the DOE G 413.3-4, 4) describe the development and demonstration activities required to advance the TRLs to 4 and 6 in order, and 5) prepare a preliminary plan tomore » conduct the development and demonstration. Results of the technology readiness assessment identified five CTE’s and found relatively low TRL’s for each of them: • Mixing, sampling, and analysis of waste slurry and melter feed: TRL-1 • Feeding, melting, and pouring: TRL-1 • Glass ceramic formulation: TRL-1 • Canister cooling and crystallization: TRL-1 • Canister decontamination: TRL-4 Although the TRL’s are low for most of these CTE’s (TRL-1), the effort required to advance them to higher values. The activities required to advance the TRL’s are listed below: • Complete this TMP • Perform a preliminary engineering study • Characterize, estimate, and simulate waste to be treated • Laboratory scale glass ceramic testing • Melter and off-gas testing with simulants • Test the mixing, sampling, and analyses • Canister testing • Decontamination system testing • Issue a requirements document • Issue a risk management document • Complete preliminary design • Integrated pilot testing • Issue a waste compliance plan A preliminary schedule and budget were developed to complete these activities as summarized in the following table (assuming 2012 dollars). TRL Budget Year MSA FMP GCF CCC CD Overall $M 2012 1 1 1 1 4 1 0.3 2013 2 2 1 1 4 1 1.3 2014 2 3 1 1 4 1 1.8 2015 2 3 2 2 4 2 2.6 2016 2 3 2 2 4 2

Waste minimisation in a hard chromiun plating Small Medium Enterprise (SME).

PubMed

Viguri, J R; Andrés, A; Irabien, A

2002-01-01

The high potential of waste stream minimisation in the metal finishing sector justifies specific studies of Small and Medium Enterprises (SME). In this work, the minimisation options of the wastes generated in a hard chromium plating activity have been analysed. The study has been performed in a small job shop company, which works in batch mode with big pieces. A process flowsheet after connecting the unit operations and determining the process inputs (raw and secondary materials) and outputs (waste streams) has been carried out. The main properties, quantity and current management of the waste streams have been shown. The obvious lack of information has been identified and finally the waste minimisation options that could be adopted by the company have been recorded.

Comparative risk assessments for the production and interim storage of glass and ceramic waste forms: Defense waste processing facility

NASA Astrophysics Data System (ADS)

Huang, J. C.; Wright, W. V.

1982-04-01

The Defense Waste Processing Facility (DWPF) for immobilizing nuclear high level waste (HLW) is scheduled to be built. High level waste is produced when reactor components are subjected to chemical separation operations. Two candidates for immobilizing this HLW are borosilicate glass and crystalline ceramic, either being contained in weld sealed stainless steel canisters. A number of technical analyses are being conducted to support a selection between these two waste forms. The risks associated with the manufacture and interim storage of these two forms in the DWPF are compared. Process information used in the risk analysis was taken primarily from a DWPF processibility analysis. The DWPF environmental analysis provided much of the necessary environmental information.

Sodium aluminum-iron phosphate glass-ceramics for immobilization of lanthanide oxide wastes from pyrochemical reprocessing of spent nuclear fuel

NASA Astrophysics Data System (ADS)

Stefanovsky, S. V.; Stefanovsky, O. I.; Kadyko, M. I.; Nikonov, B. S.

2018-03-01

Sodium aluminum (iron) phosphate glass ceramics containing of up to 20 wt.% rare earth (RE) oxides simulating pyroprocessing waste were produced by melting at 1250 °C followed by either quenching or slow cooling to room temperature. The iron-free glass-ceramics were composed of major glass and minor phosphotridymite and monazite. The iron-bearing glass-ceramics were composed of major glass and minor monazite and Na-Al-Fe orthophosphate at low waste loadings (5-10 wt.%) and major orthophosphate and minor monazite as well as interstitial glass at high waste loadings (15-20 wt.%). Slowly cooled samples contained higher amount of crystalline phases than quenched ones. Monazite is major phase for REs. Leach rates from the materials of major elements (Na, Al, Fe, P) are 10-5-10-7 g cm-2 d-1, RE elements - lower than 10-5 g cm-2 d-1.

EVALUATION OF CHEMICALLY BONDED PHOSPHATE CERAMICS FOR MERCURY STABILIZATION OF A MIXED SYNTHETIC WASTE

EPA Science Inventory

This experimental study was conducted to evaluate the stabilization and encapsulation technique developed by Argonne National Laboratory, called the Chemically Bonded Phosphate Ceramics technology for Hg- and HgCl₂-contaminated synthetic waste materials. Leachability ...

Thermodynamic and Microstructural Mechanisms in the Corrosion of Advanced Ceramic Tc-bearing Waste Forms and Thermophysical Properties

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

Hartmann, Thomas

Technetium-99 (Tc, t 1/2 = 2.13x10 5 years) is a challenge from a nuclear waste perspective and is one of the most abundant, long-lived radioisotopes found in used nuclear fuel (UNF). Within the Hanford Tank Waste Treatment and Immobilization Plant, technetium volatilizes at typical glass melting temperature, is captured in the off-gas treatment system and recycled back into the feed to eventually increase Tc-loadings of the glass. The aim of this NEUP project was to provide an alternative strategy to immobilize fission technetium as durable ceramic waste form and also to avoid the accumulation of volatile technetium within the offmore » gas melter system in the course of vitrifying radioactive effluents in a ceramic melter. During this project our major attention was turned to the fabrication of chemical durable mineral phases where technetium is structurally bond entirely as tetravalent cation. These mineral phases will act as the primary waste form with optimal waste loading and superior resistance against leaching and corrosion. We have been very successful in fabricating phase-pure micro-gram amounts of lanthanide-technetium pyrochlores by dry-chemical synthesis. However, upscaling to a gram-size synthesis route using either dry- or wet-chemical processing was not always successful, but progress can be reported on a variety of aspects. During the course of this 5-year NEUP project (including a 2-year no-cost extension) we have significantly enhanced the existing knowledge on the fabrication and properties of ceramic technetium waste forms.« less

Extended glaze firing on ceramics for hard machining: Crack healing, residual stresses, optical and microstructural aspects.

PubMed

Aurélio, Iana L; Dorneles, Lucio S; May, Liliana G

2017-02-01

To evaluate the effect of extended and conventional (manufacturer-recommended) glaze firings on crack healing, residual stresses, optical characteristics and crystalline structure of four ceramics for hard machining. Rectangular specimens were obtained by sectioning densely sintered feldspathic (FEL), leucite- (LEU), lithium disilicate- (DIS), and zirconia-reinforced lithium silicate-based (ZLS) prefabricated ceramic blocks and divided into groups according to the applied glaze firing (n=5): conventional glaze/manufacturer-recommended (G), extended glaze (EG) and control/no heat treatment (C). Defects generated by indentation were analyzed by scanning electron microscopy before and after firing (n=1) to evaluate crack healing. Residual stresses were determined by the indentation technique. Color differences (ΔE) after firing were measured by CIEDE2000 formula, and translucency variations were quantified by contrast ratio. Stability of crystalline microstructure was analyzed by X-ray diffraction. Regardless of the material, EG had greater ability than G to heal defects, and produced compressive residual stresses, while G generated tensile stresses. Color differences produced by EG were: imperceptible for FEL and LEU ceramics; perceptible, but still clinically acceptable for DIS; clinically unacceptable for ZLS. G produced no perceptible color change. The DIS and ZLS ceramics became ≈1% more opaque after G, ≈4% and ≈15%, respectively, after EG. The crystalline phase of all the ceramics remained stable after G and EG. Extended glaze firing could be an alternative to finish feldspathic, leucite-, and lithium disilicate-based ceramic restorations, since it provides greater crack healing than the conventional glaze firing. It develops tolerable residual stresses, and produces clinically acceptable color alterations, without altering the microstructure of these materials. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights

Lasers in Esthetic Dentistry: Soft Tissue Photobiomodulation, Hard Tissue Decontamination, and Ceramics Conditioning

PubMed Central

Ramalho, Karen Müller; de Freitas, Patrícia Moreira; Correa-Aranha, Ana Cecília; Bello-Silva, Marina Stella; Lopes, Roberta Marques da Graça; Eduardo, Carlos de Paula

2014-01-01

The increasing concern and the search for conservative dental treatments have resulted in the development of several new technologies. Low and high power lasers can be cited as one of these new technologies. Low power lasers act at cellular level leading to pain reduction, modulation of inflammation, and improvement of tissue healing. High power lasers act by increasing temperature and have the potential to promote microbial reduction and ablation of hard and soft tissues. The clinical application of both low and high power lasers requires specific knowledge concerning laser interaction with biological tissues, so that the correct irradiation protocol can be established. The present case report describes the clinical steps of two metal-ceramic crowns development in a 60-year-old patient. Three different laser wavelengths were applied throughout the treatment with different purposes: Nd:YAG laser (1,064 nm) for dentin decontamination, diode (660 nm) for soft tissue biomodulation, and Er:YAG laser (2,940 nm) for inner ceramic surface conditioning. Lasers were successfully applied in the present case report as coadjutant in the treatment. This coadjutant technology can be a potential tool to assist treatment to reach the final success. PMID:25147746

Advanced Ceramic Armor Materials

DTIC Science & Technology

1990-05-11

materials, toughened alumina, fiber -reinforced glass matrix composites, and multilayer-gradient materials for ballistic testing. Fabrication and...material systems: Multilayer advanced armor materials consisting of a hard ceramic faceplate bonded to a graphite fiber -reinforced glass matrix...toughened alumina, and fiber - applied studies of advanced reinforced ceramic matrix glass and glass -ceramic composites for ballistic testing. technologies

Measuring Fracture Times Of Ceramics

NASA Technical Reports Server (NTRS)

Shlichta, Paul J.; Bister, Leo; Bickler, Donald G.

1989-01-01

Electrical measurements complement or replace fast cinematography. Electronic system measures microsecond time intervals between impacts of projectiles on ceramic tiles and fracture tiles. Used in research on ceramics and ceramic-based composite materials such as armor. Hardness and low density of ceramics enable them to disintegrate projectiles more efficiently than metals. Projectile approaches ceramic tile specimen. Penetrating foil squares of triggering device activate display and recording instruments. As ceramic and resistive film break oscilloscope plots increase in electrical resistance of film.

Dilute condition corrosion behavior of glass-ceramic waste form

DOE PAGES

Crum, Jarrod V.; Neeway, James J.; Riley, Brian J.; ...

2016-08-11

Borosilicate glass-ceramics are being developed to immobilize high-level waste generated by aqueous reprocessing into a stable waste form. The corrosion behavior of this multiphase waste form is expected to be complicated by multiple phases and crystal-glass interfaces. A modified single-pass flow-through test was performed on polished monolithic coupons at a neutral pH (25 °C) and 90 °C for 33 d. The measured glass corrosion rates by micro analysis in the samples ranged from 0.019 to 0.29 g m -2 d -1 at a flow rate per surface area = 1.73 × 10 -6 m s -1. The crystal phases (oxyapatitemore » and Ca-rich powellite) corroded below quantifiable rates, by micro analysis. While, Ba-rich powellite corroded considerably in O10 sample. The corrosion rates of C1 and its replicate C20 were elevated an order of magnitude by mechanical stresses at crystal-glass interface caused by thermal expansion mismatch during cooling and unique morphology (oxyapatite clustering).« less

Dilute condition corrosion behavior of glass-ceramic waste form

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

Crum, Jarrod V.; Neeway, James J.; Riley, Brian J.

Borosilicate glass-ceramics are being developed to immobilize high-level waste generated by aqueous reprocessing into a stable waste form. The corrosion behavior of this multiphase waste form is expected to be complicated by multiple phases and crystal-glass interfaces. A modified single-pass flow-through test was performed on polished monolithic coupons at a neutral pH (25 °C) and 90 °C for 33 d. The measured glass corrosion rates by micro analysis in the samples ranged from 0.019 to 0.29 g m -2 d -1 at a flow rate per surface area = 1.73 × 10 -6 m s -1. The crystal phases (oxyapatitemore » and Ca-rich powellite) corroded below quantifiable rates, by micro analysis. While, Ba-rich powellite corroded considerably in O10 sample. The corrosion rates of C1 and its replicate C20 were elevated an order of magnitude by mechanical stresses at crystal-glass interface caused by thermal expansion mismatch during cooling and unique morphology (oxyapatite clustering).« less

Stabilization and disposal of Argonne-West low-level mixed wastes in ceramicrete waste forms.

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

Barber, D. B.; Singh, D.; Strain, R. V.

1998-02-17

The technology of room-temperature-setting phosphate ceramics or Ceramicrete{trademark} technology, developed at Argonne National Laboratory (ANL)-East is being used to treat and dispose of low-level mixed wastes through the Department of Energy complex. During the past year, Ceramicrete{trademark} technology was implemented for field application at ANL-West. Debris wastes were treated and stabilized: (a) Hg-contaminated low-level radioactive crushed light bulbs and (b) low-level radioactive Pb-lined gloves (part of the MWIR {number_sign} AW-W002 waste stream). In addition to hazardous metals, these wastes are contaminated with low-level fission products. Initially, bench-scale waste forms with simulated and actual waste streams were fabricated by acid-base reactionsmore » between mixtures of magnesium oxide powders and an acid phosphate solution, and the wastes. Size reduction of Pb-lined plastic glove waste was accomplished by cryofractionation. The Ceramicrete{trademark} process produces dense, hard ceramic waste forms. Toxicity Characteristic Leaching Procedure (TCLP) results showed excellent stabilization of both Hg and Pb in the waste forms. The principal advantage of this technology is that immobilization of contaminants is the result of both chemical stabilization and subsequent microencapsulation of the reaction products. Based on bench-scale studies, Ceramicrete{trademark} technology has been implemented in the fabrication of 5-gal waste forms at ANL-West. Approximately 35 kg of real waste has been treated. The TCLP is being conducted on the samples from the 5-gal waste forms. It is expected that because the waste forms pass the limits set by the EPAs Universal Treatment Standard, they will be sent to a radioactive-waste disposal facility.« less

Structure, mechanical and thermal behaviour of mixtures of polyester resin and dental ceramic waste

NASA Astrophysics Data System (ADS)

Peña Rodríguez, G.; Martínez Maldonado, L.; Dulce Moreno, H. J.

2016-02-01

The tensile strength and bending strength, structure and thermal behaviour of mixtures of polyester resin (P-2000) and powders (ASTM sieve 200, <75μm) of dental ceramic wastes (dentals impressions, alginate and gypsum) was reported. The samples consisted of mixtures with percentage weights of 50-50%, 60-40%, 70-30%, 80-20%, 90-10%, where the resin was the majority phase, the Mekc (4% wt) was used as catalyst. The structure was studied using SEM and XRD, the thermal behaviour using DSC, TGA and DMA, while the mechanical strength was tested using standards ASTM D790 and D638. Irregular morphology and presence of small agglomerations was observed, with particle sizes between 29.63 and 38.67μm, the presence of different phases of calcium sulphate was found, and that to the increasing the concentration of the powder, the materials becomes more crystalline, increasing its density. An average service temperature of 69.15±4.60°C was found. Vickers hardness values are reported in ranges from 18.65 to 27.96. Considering the elastic modules was established that the materials become more rigid by having more powder concentration.

Use of overburden rocks from open-pit coal mines and waste coals of Western Siberia for ceramic brick production with a defect-free structure

NASA Astrophysics Data System (ADS)

Stolboushkin, A. Yu; Ivanov, A. I.; Storozhenko, G. I.; Syromyasov, V. A.; Akst, D. V.

2017-09-01

The rational technology for the production of ceramic bricks with a defect-free structure from coal mining and processing wastes was developed. The results of comparison of physical and mechanical properties and the structure of ceramic bricks manufactured from overburden rocks and waste coal with traditional for semi-dry pressing mass preparation and according to the developed method are given. It was established that a homogeneous, defect-free brick texture obtained from overburden rocks of open-pit mines and waste coal improves the quality of ceramic wall materials produced by the method of compression molding by more than 1.5 times compared to the brick with a traditional mass preparation.

Water purification using porous ceramics prepared by recycling volcanic ash and waste glass

NASA Astrophysics Data System (ADS)

Ando, Tomohiro; Fujita, Yuki; Kakinaga, Mayu; Oka, Nobuto; Nishida, Tetsuaki

2017-11-01

Water purification was examined using porous ceramics prepared by sintering a powder mixture of volcanic ash, waste glass and a small amount of wood charcoal. The porous ceramics had cross-linked 3D-channels of which the diameter ranged from several nm to several μm. Three kilograms of porous ceramics placed in 90 L of circulating artificial seawater, in which several tropical fishes were actually living under aeration, caused a decrease in COD from 23.8 to 13.1 mg L-1 in a week. The number of coliform bacteria was almost constant in a range of 52-65 mL-1 despite that a lot of excrements were discharged frequently. The number of the coliform bacteria in the seawater examined "without the tropical fishes" decreased from 900 to 1 mL-1 in 2 weeks, and COD decreased from 37.9 to 7.9 mg L-1. It proved that several aerobic bacteria proliferating in the macropores inside the porous ceramics could effectively decompose several organic materials.

Cold crucible induction melter test for crystalline ceramic waste form fabrication: A feasibility assessment

DOE PAGES

Amoroso, Jake W.; Marra, James; Dandeneau, Christopher S.; ...

2017-01-18

The first scaled proof-of-principle cold crucible induction melter (CCIM) test to process a multiphase ceramic waste form from a simulated combined (Cs/Sr, lanthanide and transition metal fission products) commercial used nuclear fuel waste stream was recently conducted in the United States. X-ray diffraction, 2-D X-ray absorption near edge structure (XANES), electron microscopy, inductively coupled plasma-atomic emission spectroscopy (and inductively coupled plasma-mass spectroscopy for Cs), and product consistency tests were used to characterize the fabricated CCIM material. Characterization analyses confirmed that a crystalline ceramic with a desirable phase assemblage was produced from a melt using a CCIM. We identified primary hollandite,more » pyrochlore/zirconolite, and perovskite phases in addition to minor phases rich in Fe, Al, or Cs. The material produced in the CCIM was chemically homogeneous and displayed a uniform phase assemblage with acceptable aqueous chemical durability.« less

Calcium titanium silicate based glass-ceramic for nuclear waste immobilisation

NASA Astrophysics Data System (ADS)

Sharma, K.; Srivastav, A. P.; Goswami, M.; Krishnan, Madangopal

2018-04-01

Titanate based ceramics (synroc) have been studied for immobilisation of nuclear wastes due to their high radiation and thermal stability. The aim of this study is to synthesis glass-ceramic with stable phases from alumino silicate glass composition and study the loading behavior of actinides in glass-ceramics. The effects of CaO and TiO2 addition on phase evolution and structural properties of alumino silicate based glasses with nominal composition x(10CaO-9TiO2)-y(10Na2O-5 Al2O3-56SiO2-10B2O3); where z = x/y = 1.4-1.8 are reported. The glasses are prepared by melt-quench technique and characterized for thermal and structural properties using DTA and Raman Spectroscopy. Glass transition and peak crystallization temperatures decrease with increase of CaO and TiO2 content, which implies the weakening of glass network and increased tendency of glasses towards crystallization. Sphene (CaTiSiO5) and perovskite (CaTiO3) crystalline phases are confirmed from XRD which are well known stable phase for conditioning of actinides. The microsturcture and elemental analysis indicate the presence of actinide in stable crystalline phases.

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

Post-irradiation hardening of dual-cured and light-cured resin cements through machinable ceramics.

PubMed

Yoshida, Keiichi; Atsuta, Mitsuru

2006-10-01

To evaluate the surface hardness (Knoop Hardness Number) of the thin layer in three light-cured and dual-cured resin cements irradiated through or not through 2.0 mm thick machinable ceramics. A piece of adhesive polyethylene tape with a circular hole was positioned on the surface of the ceramic plate to control the cement layer (approximately 50 microm). The cement paste was placed on the ceramic surface within the circle. The ceramic plate with resin cement paste was placed on a clear micro cover glass over a zirconia ceramic block to obtain a flat surface, and the material was polymerized using a visible-light-curing unit. The surface hardness was recorded at a series of time intervals up to 5 days, starting from the end of a light-irradiation period. The hardness steadily increased with post-irradiation time and tended towards a maximum, usually reached after 1 or 2 days. In all cases, the increase in hardness was relatively rapid over the first 30 minutes and continued at a lower rate thereafter. The dual-cured resin cement for each material showed a significantly higher hardness value than the light-cured resin cement irradiated either through or not through ceramics at all post-irradiation times. The resin cements cured through ceramic for each material were significantly less hard compared with those cured not through ceramics at all post-irradiation times.

Mechanical properties of commercial high strength ceramic core materials.

PubMed

Rizkalla, A S; Jones, D W

2004-02-01

The objective of the present study is to evaluate and compare the flexural strength, dynamic elastic moduli and true hardness (H(o)) values of commercial Vita In-Ceram alumina core and Vita In-Ceram matrix glass with the standard aluminous porcelain (Hi-Ceram and Vitadur), Vitadur N and Dicor glass and glass-ceramic. The flexural strength was evaluated (n=5) using 3-point loading and a servo hydraulic Instron testing machine at a cross head speed of 0.5 mm/min. The density of the specimens (n=3) was measured by means of the water displacement technique. Dynamic Young's shear and bulk moduli and Poisson's ratio (n=3) were measured using a non-destructive ultrasonic technique using 10 MHz lithium niobate crystals. The true hardness (n=3) was measured using a Knoop indenter and the fracture toughness (n=3) was determined using a Vickers indenter and a Tukon hardness tester. Statistical analysis of the data was conducted using ANOVA and a Student-Newman-Keuls (SNK) rank order multiple comparative test. The SNK rank order test analysis of the mean flexural strength was able to separate five commercial core materials into three significant groups at p=0.05. Vita In-Ceram alumina and IPS Empress 2 exhibited significantly higher flexural strength than aluminous porcelains and IPS Empress at p=0.05. The dynamic elastic moduli and true hardness of Vita In-Ceram alumina core were significantly higher than the rest of the commercial ceramic core materials at p=0.05. The ultrasonic test method is a valuable mechanical characterization tool and was able to statistically discriminate between the chemical and structural differences within dental ceramic materials. Significant correlation was obtained between the dynamic Young's modulus and true hardness, p=0.05.

Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

PubMed

Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

2013-01-01

The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

Hard-on-Hard Lubrication in the Artificial Hip under Dynamic Loading Conditions

PubMed Central

Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S.; Heitzmann, Daniel W. W.; Kretzer, J. Philippe

2013-01-01

The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal. PMID:23940772

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.

Properties of Clay for Ceramics with Rock Waste for Production Structural Block by Pressing and Firing

NASA Astrophysics Data System (ADS)

Cerqueira, N. A.; Choe, D.; Alexandre, J.; Azevedo, A. R. G.; Xavier, C. G.; Souza, V. B.

Building work requires optimization of materials and labor, so that the execution of its subsystems contribute to the quality, reduce costs, decrease waste in buildings, productivity, practicality and especially agility. Thus, the fitting blocks can contribute in this direction. This work therefore consists of physical characterization (determination of fitness levels, grain size and bulk density), chemical (EDX) and thermal (DTA and TGA) sample clay Campos dos Goytacazes-RJ and waste rock ornamental Cachoeiro de Itapemirim-ES, to verify potential for producing red ceramic blocks, pressed and burned, male and female type. The output of block will be with different pe rcentages of incorporation of residues of ornamental rocks (0%, 5% and 10%). With the results obtained, it was found that the raw materials under consideration has the potential for application in the production of ceramic articles.

Zirconia toughened mica glass ceramics for dental restorations.

PubMed

Gali, Sivaranjani; K, Ravikumar; Murthy, B V S; Basu, Bikramjit

2018-03-01

The objective of the present study is to understand the role of yttria stabilized zirconia (YSZ) in achieving the desired spectrum of clinically relevant mechanical properties (hardness, elastic modulus, fracture toughness and brittleness index) and chemical solubility of mica glass ceramics. The glass-zirconia mixtures with varying amounts of YSZ (0, 5, 10, 15 and 20wt.%) were ball milled, compacted and sintered to obtain pellets of glass ceramic-YSZ composites. Phase analysis was carried out using X-ray diffraction and microstructural characterization with SEM revealed the crystal morphology of the composites. Mechanical properties such as Vickers hardness, elastic modulus, indentation fracture toughness and chemical solubility were assessed. Phase analysis of sintered pellets of glass ceramic-YSZ composites revealed the characteristic peaks of fluorophlogopite (FPP) and tetragonal zirconia. Microstructural investigation showed plate and lath-like interlocking mica crystals with embedded zirconia. Vickers hardness of 9.2GPa, elastic modulus of 125GPa, indentation toughness of 3.6MPa·m 1/2 , and chemical solubility of 30μg/cm 2 (well below the permissible limit) were recorded with mica glass ceramics containing 20wt.% YSZ. An increase in hardness and toughness of the glass ceramic-YSZ composites with no compromise on their brittleness index and chemical solubility has been observed. Such spectrum of properties can be utilised for developing a machinable ceramic for low stress bearing inlays, onlays and veneers. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Waste water purification using new porous ceramics prepared by recycling waste glass and bamboo charcoal

NASA Astrophysics Data System (ADS)

Nishida, Tetsuaki; Morimoto, Akane; Yamamoto, Yoshito; Kubuki, Shiro

2017-12-01

New porous ceramics (PC) prepared by recycling waste glass bottle of soft drinks (80 mass%) and bamboo charcoal (20 mass%) without any binder was applied to the waste water purification under aeration at 25 °C. Artificial waste water (15 L) containing 10 mL of milk was examined by combining 15 mL of activated sludge and 750 g of PC. Biochemical oxygen demand (BOD) showed a marked decrease from 178 to 4.0 (±0.1) mg L-1 in 5 days and to 2.0 (±0.1) mg L-1 in 7 days, which was equal to the Environmental Standard for the river water (class A) in Japan. Similarly, chemical oxygen demand (COD) decreased from 158 to 3.6 (±0.1) mg L-1 in 5 days and to 2.2 (±0.1) mg L-1 in 9 days, which was less than the Environmental Standard for the Seawater (class B) in Japan: 3.0 mg L-1. These results prove the high water purification ability of the PC, which will be effectively utilized for the purification of drinking water, fish preserve water, fish farm water, etc.

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

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.

Glycerin purification using asymmetric nano-structured ceramic membranes from production of waste fish oil biodiesel

NASA Astrophysics Data System (ADS)

Maghami, M.; Sadrameli, S. M.; Shamloo, M.

2018-02-01

Biodiesel is an environmental friendly alternative liquid transportation fuel that can be used in diesel engines without major modifications. The scope of this research work is to produce biodiesel from waste fish oil and its purification from the byproducts using a ceramic membrane. Transesterification of waste fish oil was applied for the biodiesel production using methanol in the presence of KOH as a catalyst. Effect of catalyst weight percent, temperature and methanol to oil molar ratio (MR) on the biodiesel yield have been studied and the results show that highest methyl ester yield of 79.2% has been obtained at 60 °C, MR: 6 and 1% KOH. The produced biodiesel purified by a ceramic membrane. Membrane flux and glycerin removal at different operating conditions such as temperature, trans-membrane pressures and cross flow velocities have been measured. Glycerin purity by membrane method is 99.97% by weight at the optimum condition. The highest membrane flux occurred at 50 °C temperature, 1 bar pressure and 3 m/s velocity.

Prototype Development of Remote Operated Hot Uniaxial Press (ROHUP) to Fabricate Advanced Tc-99 Bearing Ceramic Waste Forms - 13381

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

Alaniz, Ariana J.; Delgado, Luc R.; Werbick, Brett M.

The objective of this senior student project is to design and build a prototype construction of a machine that simultaneously provides the proper pressure and temperature parameters to sinter ceramic powders in-situ to create pellets of rather high densities of above 90% (theoretical). This ROHUP (Remote Operated Hot Uniaxial Press) device is designed specifically to fabricate advanced ceramic Tc-99 bearing waste forms and therefore radiological barriers have been included in the system. The HUP features electronic control and feedback systems to set and monitor pressure, load, and temperature parameters. This device operates wirelessly via portable computer using Bluetooth{sup R} technology.more » The HUP device is designed to fit in a standard atmosphere controlled glove box to further allow sintering under inert conditions (e.g. under Ar, He, N{sub 2}). This will further allow utilizing this HUP for other potential applications, including radioactive samples, novel ceramic waste forms, advanced oxide fuels, air-sensitive samples, metallic systems, advanced powder metallurgy, diffusion experiments and more. (authors)« less

Development in laser peening of advanced ceramics

NASA Astrophysics Data System (ADS)

Shukla, Pratik; Smith, Graham C.; Waugh, David G.; Lawrence, Jonathan

2015-07-01

Laser peening is a well-known process applicable to surface treat metals and alloys in various industrial sectors. Research in the area of laser peening of ceramics is still scarce and a complete laser-ceramic interaction is still unreported. This paper focuses on laser peening of SiC ceramics employed for cutting tools, armor plating, dental and biomedical implants, with a view to elucidate the unreported work. A detailed investigation was conducted with 1064nm Nd:YAG ns pulse laser to first understand the surface effects, namely: the topography, hardness, KIc and the microstructure of SiC advanced ceramics. The results showed changes in surface roughness and microstructural modification after laser peening. An increase in surface hardness was found by almost 2 folds, as the diamond footprints and its flaws sizes were considerably reduced, thus, enhancing the resistance of SiC to better withstand mechanical impact. This inherently led to an enhancement in the KIc by about 42%. This is attributed to an induction of compressive residual stress and phase transformation. This work is a first-step towards the development of a 3-dimensional laser peening technique to surface treat many advanced ceramic components. This work has shown that upon tailoring the laser peening parameters may directly control ceramic topography, microstructure, hardness and the KIc. This is useful for increasing the performance of ceramics used for demanding applications particularly where it matters such as in military. Upon successful peening of bullet proof vests could result to higher ballistic strength and resistance against higher sonic velocity, which would not only prevent serious injuries, but could also help to save lives of soldiers on the battle fields.

Ceramic Processing

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

EWSUK,KEVIN G.

1999-11-24

Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referredmore » to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.« less

Plutonium immobilization in glass and ceramics

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

Knecht, D.A.; Murphy, W.M.

1996-05-01

The Materials Research Society Nineteenth Annual Symposium on the Scientific Basis for Nuclear Waste Management was held in Boston on November 27 to December 1, 1995. Over 150 papers were presented at the Symposium dealing with all aspects of nuclear waste management and disposal. Fourteen oral sessions and on poster session included a Plenary session on surplus plutonium dispositioning and waste forms. The proceedings, to be published in April, 1996, will provide a highly respected, referred compilation of the state of scientific development in the field of nuclear waste management. This paper provides a brief overview of the selected Symposiummore » papers that are applicable to plutonium immobilization and plutonium waste form performance. Waste forms that were described at the Symposium cover most of the candidate Pu immobilization options under consideration, including borosilicate glass with a melting temperature of 1150 {degrees}C, a higher temperature (1450 {degrees}C) lanthanide glass, single phase ceramics, multi-phase ceramics, and multi-phase crystal-glass composites (glass-ceramics or slags). These Symposium papers selected for this overview provide the current status of the technology in these areas and give references to the relevant literature.« less

Method for preparing ceramic composite

DOEpatents

Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

1996-01-01

A process for preparing ceramic composite comprising blending TiC particulates, Al.sub.2 O.sub.3 particulates and nickle aluminide and consolidating the mixture at a temperature and pressure sufficient to produce a densified ceramic composite having fracture toughness equal to or greater than 7 MPa m.sup.1/2, a hardness equal to or greater than 18 GPa.

Experimental determination of the speciation, partitioning, and release of perrhenate as a chemical surrogate for pertechnetate from a sodalite-bearing multiphase ceramic waste form

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

Pierce, Eric M.; Lukens, Wayne W.; Fitts, Jeff. P.

2013-12-01

A key component to closing the nuclear fuel cycle is the storage and disposition of nuclear waste in geologic systems. Multiphase ceramic waste forms have been studied extensively as a potential host matrix for nuclear waste. Understanding the speciation, partitioning, and release behavior of radionuclides immobilized in multiphase ceramic waste forms is a critical aspect of developing the scientific and technical basis for nuclear waste management. In this study, we evaluated a sodalite-bearing multiphase ceramic waste form (i.e., fluidized-bed steam reform sodium aluminosilicate [FBSR NAS] product) as a potential host matrix for long-lived radionuclides, such as technetium (99Tc). The FBSRmore » NAS material consists primarily of nepheline (ideally NaAlSiO4), anion-bearing sodalites (ideally M8[Al6Si6O24]X2, where M refers to alkali and alkaline earth cations and X refers to monovalent anions), and nosean (ideally Na8[AlSiO4]6SO4). Bulk X-ray absorption fine structure analysis of the multiphase ceramic waste form, suggest rhenium (Re) is in the Re(VII) oxidation state and has partitioned to a Re-bearing sodalite phase (most likely a perrhenate sodalite Na8[Al6Si6O24](ReO4)2). Rhenium was added as a chemical surrogate for 99Tc during the FBSR NAS synthesis process. The weathering behavior of the FBSR NAS material was evaluated under hydraulically unsaturated conditions with deionized water at 90 ?C. The steady-state Al, Na, and Si concentrations suggests the weathering mechanisms are consistent with what has been observed for other aluminosilicate minerals and include a combination of ion exchange, network hydrolysis, and the formation of an enriched-silica surface layer or phase. The steady-state S and Re concentrations are within an order of magnitude of the nosean and perrhenate sodalite solubility, respectively. The order of magnitude difference between the observed and predicted concentration for Re and S may be associated with the fact that the anion

Comparison of mechanical properties of three machinable ceramics with an experimental fluorophlogopite glass ceramic.

PubMed

Leung, Brian T W; Tsoi, James K H; Matinlinna, Jukka P; Pow, Edmond H N

2015-09-01

Fluorophlogopite glass ceramic (FGC) is a biocompatible, etchable, and millable ceramic with fluoride releasing property. However, its mechanical properties and reliability compared with other machinable ceramics remain undetermined. The purpose of this in vitro study was to compare the mechanical properties of 3 commercially available millable ceramic materials, IPS e.max CAD, Vitablocs Mark II, and Vita Enamic, with an experimental FGC. Each type of ceramic block was sectioned into beams (n=15) of standard dimensions of 2×2×15 mm. Before mechanical testing, specimens of the IPS e.max CAD group were further fired for final crystallization. Flexural strength was determined by the 3-point bend test with a universal loading machine at a cross head speed of 1 mm/min. Hardness was determined with a hardness tester with 5 Vickers hardness indentations (n=5) using a 1.96 N load and a dwell time of 15 seconds. Selected surfaces were examined by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Data were analyzed by the 1-way ANOVA test and Weibull analysis (α=.05). Weibull parameters, including the Weibull modulus (m) as well as the characteristic strength at 63.2% (η) and 10.0% (B10), were obtained. A significant difference in flexural strength (P<.001) was found among groups, with IPS e.max CAD (341.88 ±40.25 MPa)>Vita Enamic (145.95 ±12.65 MPa)>Vitablocs Mark II (106.67 ±18.50 MPa), and FGC (117.61 ±7.62 MPa). The Weibull modulus ranged from 6.93 to 18.34, with FGC showing the highest Weibull modulus among the 4 materials. The Weibull plot revealed that IPS e.max CAD>Vita Enamic>FGC>Vitablocs Mark II for the characteristic strength at both 63.2% (η) and 10.0% (B10). Significant difference in Vickers hardness among groups (P<.001) was found with IPS e.max CAD (731.63 ±30.64 H(V))>Vitablocs Mark II (594.74 ±25.22 H(V))>Vita Enamic (372.29 ±51.23 H(V))>FGC (153.74 ±23.62 H(V)). The flexural strength and Vickers hardness of IPS e.max CAD

Feasible Recycling of Industrial Waste Coal Gangue for Preparation of Mullite Based Ceramic Proppant

NASA Astrophysics Data System (ADS)

Li, Guomin; Ma, Haiqiang; Tian, Yuming; Wang, Kaiyue; Zhou, Yi; Wu, Yaqiao; Zou, Xinwei; Hao, Jianying; Bai, Pinbo

2017-09-01

Industrial waste coal gangue was successfully utilized to prepare the mullite-based ceramic proppants. The experiments involved the pelletizing technology of proppant through intensive mixer and following the sintering process under different temperatures. The crystalline phase, microstructure, density and breakage ratio of the proppants were investigated. The results showed that with the increasing of sintering temperature, the crystalline phases were transformed to rod-like mullite, which formed the cross-linked structure, improving the densification of proppants. Consequently, the breakage ratio under the closure pressure of 35 MPa exhibited declining trend and reached the minimum value of 6.8% at 1450 °C. Owing to the easy preparation, feasible design, low cost and moderate breakage ratio, the mullite-based ceramic proppant prepared by coal gangue and bauxite is promising candidate for fracturing proppants in future applications.

Effects of multiple firings on the microstructure of zirconia and veneering ceramics.

PubMed

Alkurt, Murat; Yeşil Duymus, Zeynep; Gundogdu, Mustafa

2016-01-01

The aim of study was to evaluate the effects of multiple firings on the microstructures of zirconia and two ceramics. Vita VM9 (VMZ) and Cerabien ZR (C-Z) ceramics on a zirconia framework and zirconia without veneering ceramic (WO-Z) were evaluated. Firing methods included firing two, five, and ten times (n=10). The effects of multiple firings on the surface hardness of the materials were evaluated using a Vickers hardness (HV) tester. Data were analyzed by two-way ANOVA and Tukey's test (α=0.05). After firing five and ten times, the hardness of VM-Z and C-Z increased significantly (p<0.001). The HVs of the Cerabien ZR and Vita VM9 veneering ceramics were similar (p>0.05). In the XRD analysis, zirconia had similar tetragonal (t)-monoclinic (m) phase transformations of Y-TZP after the different firing times. Clinically, multiple firings did not affect the microstructure of zirconia, but the structures of the two ceramics were affected.

Environment Conscious Ceramics (Ecoceramics): An Eco-Friendly Route to Advanced Ceramic Materials

NASA Technical Reports Server (NTRS)

Singh, M.

2001-01-01

Environment conscious ceramics (Ecoceramics) are a new class of materials, which can be produced with renewable natural resources (wood) or wood wastes (wood sawdust). This technology provides an eco-friendly route to advanced ceramic materials. Ecoceramics have tailorable properties and behave like ceramic materials manufactured by conventional approaches. Silicon carbide-based ecoceramics have been fabricated by reactive infiltration of carbonaceous preforms by molten silicon or silicon-refractory metal alloys. The fabrication approach, microstructure, and mechanical properties of SiC-based ecoceramics are presented.

Method for preparing ceramic composite

DOEpatents

Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

1996-01-09

A process is disclosed for preparing ceramic composite comprising blending TiC particulates, Al{sub 2}O{sub 3} particulates and nickel aluminide and consolidating the mixture at a temperature and pressure sufficient to produce a densified ceramic composite having fracture toughness equal to or greater than 7 MPa m{sup 1/2}, a hardness equal to or greater than 18 GPa. 5 figs.

In vitro Fracture strength and hardness of different computer-aided design/computer-aided manufacturing inlays.

PubMed

Sagsoz, O; Yildiz, M; Hojjat Ghahramanzadeh, A S L; Alsaran, A

2018-03-01

The purpose of this study was to examine the fracture strength and surface microhardness of computer-aided design/computer-aided manufacturing (CAD/CAM) materials in vitro. Mesial-occlusal-distal inlays were made from five different CAD/CAM materials (feldspathic ceramic, CEREC blocs; leucite-reinforced ceramic, IPS Empress CAD; resin nano ceramic, 3M ESPE Lava Ultimate; hybrid ceramic, VITA Enamic; and lithium disilicate ceramic, IPS e.max CAD) using CEREC 4 CAD/CAM system. Samples were adhesively cemented to metal analogs with a resin cement (3M ESPE, U200). The fracture tests were carried out with a universal testing machine. Furthermore, five samples were prepared from each CAD/CAM material for micro-Vickers hardness test. Data were analyzed with statistics software SPSS 20 (IBM Corp., New York, USA). Fracture strength of lithium disilicate inlays (3949 N) was found to be higher than other ceramic inlays (P < 0.05). There was no difference between other inlays statistically (P > 0.05). The highest micro-Vickers hardness was measured in lithium disilicate samples, and the lowest was in resin nano ceramic samples. Fracture strength results demonstrate that inlays can withstand the forces in the mouth. Statistical results showed that fracture strength and micro-Vickers hardness of feldspathic ceramic, leucite-reinforced ceramic, and lithium disilicate ceramic materials had a positive correlation.

Investigation of the usage of centrifuging waste of mineral wool melt (CMWW), contaminated with phenol and formaldehyde, in manufacturing of ceramic products.

PubMed

Kizinievič, Olga; Balkevičius, Valdas; Pranckevičienė, Jolanta; Kizinievič, Viktor

2014-08-01

Large amounts of centrifuging waste of mineral wool melt (CMWW) are created during the production of mineral wool. CMWW is technogenic aluminum silicate raw material, formed from the particles of undefibred melt (60-70%) and mineral wool fibers (30-40%). 0.3-0.6% of organic binder with phenol and formaldehyde in its composition exists in this material. Objective of the research is to investigate the possibility to use CMWW as an additive for the production of ceramic products, by neutralising phenol and formaldehyde existing in CMWW. Formation masses were prepared by incorporating 10%, 20% and 30% of CMWW additive and burned at various temperatures. It was identified that the amount of 10-30% of CMWW additive influences the following physical and mechanical properties of the ceramic body: lowers drying and firing shrinkage, density, increases compressive strength and water absorption. Investigations carried out show that CMWW waste can be used for the production of ceramic products of various purposes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ceramic Coatings for Corrosion Resistant Nuclear Waste Container Evaluated in Simulated Ground Water at 90?C

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

Haslam, J J; Farmer, J C

2004-03-31

Ceramic materials have been considered as corrosion resistant coatings for nuclear waste containers. Their suitability can be derived from the fully oxidized state for selected metal oxides. Several types of ceramic coatings applied to plain carbon steel substrates by thermal spray techniques have been exposed to 90 C simulated ground water for nearly 6 years. In some cases no apparent macroscopic damage such as coating spallation was observed in coatings. Thermal spray processes examined in this work included plasma spray, High Velocity Oxy Fuel (HVOF), and Detonation Gun. Some thermal spray coatings have demonstrated superior corrosion protection for the plainmore » carbon steel substrate. In particular the HVOF and Detonation Gun thermal spray processes produced coatings with low connected porosity, which limited the growth rate of corrosion products. It was also demonstrated that these coatings resisted spallation of the coating even when an intentional flaw (which allowed for corrosion of the carbon steel substrate underneath the ceramic coating) was placed in the coating. A model for prediction of the corrosion protection provided by ceramic coatings is presented. The model includes the effect of the morphology and amount of the porosity within the thermal spray coating and provides a prediction of the exposure time needed to produce a crack in the ceramic coating.« less

Magnetic-field sensing coil embedded in ceramic for measuring ambient magnetic field

DOEpatents

Takahashi, Hironori

2004-02-10

A magnetic pick-up coil for measuring magnetic field with high specific sensitivity, optionally with an electrostatic shield (24), having coupling elements (22) with high winding packing ratio, oriented in multiple directions, and embedded in ceramic material for structural support and electrical insulation. Elements of the coil are constructed from green ceramic sheets (200) and metallic ink deposited on surfaces and in via holes of the ceramic sheets. The ceramic sheets and the metallic ink are co-fired to create a monolithic hard ceramic body (20) with metallized traces embedded in, and placed on exterior surfaces of, the hard ceramic body. The compact and rugged coil can be used in a variety of environments, including hostile conditions involving ultra-high vacuum, high temperatures, nuclear and optical radiation, chemical reactions, and physically demanding surroundings, occurring either individually or in combinations.

Pumpable/injectable phosphate-bonded ceramics

DOEpatents

Singh, Dileep; Wagh, Arun S.; Perry, Lamar; Jeong, Seung-Young

2001-01-01

A pumpable ceramic composition is provided comprising an inorganic oxide, potassium phosphate, and an oxide coating material. Also provided is a method for preparing pumpable ceramic-based waste forms comprising selecting inorganic oxides based on solubility, surface area and morphology criteria; mixing the selected oxides with phosphate solution and waste to form a first mixture; combining an additive to the first mixture to create a second mixture; adding water to the second mixture to create a reactive mixture; homogenizing the reactive mixture; and allowing the reactive mixture to cure.

Method of determining elastic and plastic mechanical properties of ceramic materials using spherical indenters

DOEpatents

Adler, Thomas A.

1996-01-01

The invention pertains a method of determining elastic and plastic mechanical properties of ceramics, intermetallics, metals, plastics and other hard, brittle materials which fracture prior to plastically deforming when loads are applied. Elastic and plastic mechanical properties of ceramic materials are determined using spherical indenters. The method is most useful for measuring and calculating the plastic and elastic deformation of hard, brittle materials with low values of elastic modulus to hardness.

The Role of Ceramics in a Resurgent Nuclear Industry

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

Marra, J

2006-02-28

With fuel oil and natural gas prices near record highs and worldwide energy demands increasing at an alarming rate, there is growing interest in revitalization of the nuclear power industry within the United States and across the globe. Ceramic materials have long played a very important part in the commercial nuclear industry with applications throughout the entire fuel cycle; from fuel fabrication to waste stabilization. As the international community begins to look at advanced fuel cycles that minimize waste and increase proliferation resistance, ceramic materials will play an even larger role. Many of the advanced reactor concepts being evaluated operatemore » at high-temperature requiring the use of durable, heat-resistant materials. Ceramic fuels are being investigated for a variety of Generation IV reactor concepts. These include the traditional TRISO-coated particles as well as advanced inert-matrix fuels. In order to minimize wastes and legacy materials, ceramic processes are also being applied to fuel reprocessing operations. Ceramic materials continue to provide a vital contribution in ''closing the fuel cycle'' by stabilization of associated low-level and high-level wastes in highly durable grout, ceramics, and glass. In the next five years, programs that are currently in the conceptual phase will begin laboratory- and engineering-scale demonstrations. This will require production-scale demonstrations of several ceramic technologies from fuel form development to advanced stabilization methods. Within the next five to ten years, these demonstrations will move to even larger scales and will also include radioactive demonstrations of these advanced technologies. These radioactive demonstrations are critical to program success and will require advances in ceramic materials associated with nuclear energy applications.« less

Mechanical properties of zirconia reinforced lithium silicate glass-ceramic.

PubMed

Elsaka, Shaymaa E; Elnaghy, Amr M

2016-07-01

The aim of this study was to assess the mechanical properties of recently introduced zirconia reinforced lithium silicate glass-ceramic. Two types of CAD/CAM glass-ceramics (Vita Suprinity (VS); zirconia reinforced lithium silicate and IPS e.max CAD (IC); lithium disilicate) were used. Fracture toughness, flexural strength, elastic modulus, hardness, brittleness index, and microstructures were evaluated. Data were analyzed using independent t tests. Weibull analysis of flexural strength data was also performed. VS had significantly higher fracture toughness (2.31±0.17MPam(0.5)), flexural strength (443.63±38.90MPa), elastic modulus (70.44±1.97GPa), and hardness (6.53±0.49GPa) than IC (P<0.001). On the other hand, VS glass-ceramic revealed significantly a higher brittleness index (2.84±0.26μm(-1/2)) (lower machinability) than IC glass-ceramic (P<0.05). VS demonstrated a homogeneous fine crystalline structure while, IC revealed a structure with needle-shaped fine-grained crystals embedded in a glassy matrix. The VS glass-ceramic revealed a lower probability of failure and a higher strength than IC glass-ceramic according to Weibull analysis. The VS zirconia reinforced lithium silicate glass-ceramic revealed higher mechanical properties compared with IC lithium disilicate glass-ceramic. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Recycling and utilisation of industrial solid waste: an explorative study on gold deposit tailings of ductile shear zone type in China.

PubMed

Liu, Rui; Huang, Fei; Du, Runxiang; Zhao, Chunming; Li, Yongli; Yu, Haoran

2015-06-01

Tailings are solid waste arising from mineral processing. This type of waste can cause severe damage to the environment during stockpiling as a result of the leaching of something harmful into the ecosystem. Gold deposit of ductile shear zone type is an important type of gold deposit, and the recycling of its tailings has been challenging researchers for a long time. In this article, the characteristics of this type of tailings were systematically studied by using modern technical means. Considering the characteristics of the tailings, clay was selected to make up for the shortcomings of the tailings and improve their performance. Water and raw materials were mixed to produce green bodies, which are subsequently sintered into ceramic bodies at 980 °C~1020 °C (sintering temperature). The results showed that some new kinds of mineral phases, such as mullite, anorthite and orthoclase, appear in ceramic bodies. Furthermore, the ceramic bodies have a surface hardness of 5 to 6 (Mohs scale), and their water absorption and modulus of rupture can meet some technical requirements of ceramic materials described in ISO 13006-2012 and GB 5001-1985. These gold mine tailings can be made into ceramic tiles, domestic ceramic bodies, and other kinds of ceramic bodies for commercial and industrial purposes after further improvements. © The Author(s) 2015.

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

Evaluation of a novel multiple phase veneering ceramic.

PubMed

Sinthuprasirt, Pannapa; van Noort, Richard; Moorehead, Robert; Pollington, Sarah

2015-04-01

To produce a new veneering ceramic based on the production of a multiple phase glass-ceramic with improved performance in terms of strength and toughness. A composition of 60% leucite, 20% diopside and 20% feldspathic glass was prepared, blended and a heat treatment schedule of 930°C for 5 min was derived from differential thermal analysis (DTA) of the glasses. X-ray diffraction (XRD) and SEM analysis determined the crystalline phases and microstructure. Chemical solubility, biaxial flexural strength (BFS), fracture toughness, hardness, total transmittance and coefficient of thermal expansion (CTE) were all measured in comparison to a commercial veneering ceramic (VITA VM9). Thermal shock resistance of the leucite-diopside and VITA VM9 veneered onto a commercial high strength zirconia (Vita In-Ceram YZ) was also assessed. Statistical analysis was undertaken using Independent Samples t-test. Weibull analysis was employed to examine the reliability of the strength data. The mean chemical solubility was 6 μg/cm(2) for both ceramics (P=1.00). The mean BFS was 109 ± 8 MPa for leucite-diopside ceramic and 79 ± 11 MPa for VITA VM9 ceramic (P=0.01). Similarly, the leucite-diopside ceramic demonstrated a significantly higher fracture toughness and hardness. The average total transmittance was 46.3% for leucite-diopside ceramic and 39.8% for VITA VM9 (P=0.01). The leucite-diopside outperformed the VITA VM9 in terms of thermal shock resistance. Significance This novel veneering ceramic exhibits significant improvements in terms of mechanical properties, yet retains a high translucency and is the most appropriate choice as a veneering ceramic for a zirconia base core material. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Structure, crystallization and dielectric resonances in 2-13 GHz of waste-derived glass-ceramic

NASA Astrophysics Data System (ADS)

Yao, Rui; Liao, SongYi; Chen, XiaoYu; Wang, GuangRong; Zheng, Feng

2016-12-01

Structure, kinetics of crystallization, and dielectric resonances of waste-derived glass-ceramic prepared via quench-heating route were studied as a function of dosage of iron ore tailing (IOT) within 20-40 wt% using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vector network analyzer (VNA) measurements. The glass-ceramic mainly consisted of ferrite crystals embedded in borosilicate glass matrix. Crystallization kinetics and morphologies of ferrite crystals as well as coordination transformation of boron between [BO4] and [BO3] in glass network were adjustable by changing the amount of IOT. Dielectric resonances in 6-13 GHz were found to be dominated by oscillations of Ca2+ cations in glass network with [SiO4] units on their neighboring sites. Ni2+ ions made a small contribution to those resonances. Diopside formed when IOT exceeded 35 wt%, which led to weakening of the resonances.

Environment Conscious, Biomorphic Ceramics from Pine and Jelutong Wood Precursors

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Yee, Bo-Moon; Gray, Hugh R. (Technical Monitor)

2002-01-01

Environment conscious, biomorphic ceramics have been fabricated from pine and jelutong wood precursors. A carbonaceous preform is produced through wood pyrolysis and subsequent infiltration with oxides (ZrO2 sols) and liquid silicon to form ceramics. These biomorphic ceramics show a wide variety of microstructures, densities, and hardness behavior that are determined by the type of wood and infiltrants selected.

Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite

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

Zhang, Zhikun; Zhang, Lei; Li, Aimin, E-mail: leeam@dlut.edu.cn

Highlights: • Glass ceramic composite is prepared from oil shale fly ash and MSWI bottom ash. • A novel method for the production of glass ceramic composite is presented. • It provides simple route and lower energy consumption in terms of recycling waste. • The vitrified slag can promote the sintering densification process of glass ceramic. • The performances of products decrease with the increase of oil shale fly ash content. - Abstract: Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment.more » In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2 h) showed the properties of density of 1.92 ± 0.05 g/cm{sup 3}, weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was

Letter report on PCT/Monolith glass ceramic corrosion tests

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

Crawford, Charles L.

2015-09-24

The Savannah River National Laboratory (SRNL) is collaborating with personnel from Pacific Northwest National Laboratory (PNNL) to study advanced waste form glass ceramics for immobilization of waste from Used Nuclear Fuel (UNF) separations processes. The glass ceramic waste forms take advantage of both crystalline and glassy phases where ‘troublesome’ elements (e.g., low solubility in glass or very long-lived) partition to highly durable ceramic phases with the remainder of elements residing in the glassy phase. The ceramic phases are tailored to create certain minerals or unique crystalline structures that can host the radionuclides by binding them in their specific crystalline networkmore » while not adversely impacting the residual glass network (Crum et al., 2011). Glass ceramics have been demonstrated using a scaled melter test performed in a pilot scale (1/4 scale) cold crucible induction melter (CCIM) (Crum et al., 2014; Maio et al., 2015). This report summarizes recent results from both Phase I and Phase II bench scale tests involving crucible fabrication and corrosion testing of glass ceramics using the Product Consistency Test (PCT). Preliminary results from both Phase I and Phase II bench scale tests involving statistically designed matrices have previously been reported (Crawford, 2013; Crawford, 2014).« less

Effects of soda-lime-silica waste glass on mullite formation kinetics and micro-structures development in vitreous ceramics.

PubMed

Marinoni, Nicoletta; D'Alessio, Daniela; Diella, Valeria; Pavese, Alessandro; Francescon, Ferdinando

2013-07-30

The effects of soda-lime waste glass, from the recovery of bottle glass cullet, in partial replacement of Na-feldspar for sanitary-ware ceramic production are discussed. Attention is paid to the mullite growth kinetics and to the macroscopic properties of the final output, the latter ones depending on the developed micro-structures and vitrification grade. Measurements have been performed by in situ high temperature X-ray powder diffraction, scanning electron microscopy, thermal dilatometry, water absorption and mechanical testing. Glass substituting feldspar from 30 to 50 wt% allows one (i) to accelerate the mullite growth reaction kinetics, and (ii) to achieve macroscopic features of the ceramic output that comply with the latest technical requirements. The introduction of waste glass leads to (i) a general saving of fuel and reduction of the CO2-emissions during the firing stage, (ii) a preservation of mineral resources in terms of feldspars, and (iii) an efficient management of the bottle glass refuse by readdressing a part of it in the sanitary-ware manufacturing. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ageing of a phosphate ceramic used to immobilize chloride-contaminated actinide waste

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

Metcalfe, Brian; Donald, Ian W.; Fong, Shirley K.

2009-03-31

At AWE, we have developed a process for the immobilization of ILW waste containing a significant quantity of chloride with Ca 3(PO 4) 2 as the host material. Waste ions are incorporated into two phosphate-based phases, chlorapatite [Ca 5(PO 4) 3Cl] and spodiosite [Ca 2(PO 4)Cl]. Non-active trials performed at AWE with Sm as the actinide surrogate demonstrated the durability of these phases in aqueous solution. Trials of the process, in which actinide-doped materials were used, wer performed at PNNL where the waste form was found to be resistant to aqueous leaching. Initial leach trials conducted on 239Pu / 241Ammore » loaded ceramic at 40°C/28 days gave normalized mass losses of 1.2 x 10 -5 g.m -2 and 2.7 x 10 -3 g.m -2 for Pu and Cl respectively. In order to assess the response of the phases to radiation-induced damage, accelerated ageing trials were performed on samples in which the 239Pu was replaced with 238Pu. No changes to the crystalline structure of the waste were detected in the XRD patterns after the samples had experienced an α radiation dose of 4 x 10 18 g -1. Leach trials showed that there was an increase in the P and Ca release rates but no change in the Pu release rate.« less

Abrasive wear of ceramic wear protection at ambient and high temperatures

NASA Astrophysics Data System (ADS)

Varga, M.; Adam, K.; Tumma, M.; Alessio, K. O.

2017-05-01

Ceramic wear protection is often applied in abrasive conditions due to their excellent wear resistance. This is especially necessary in heavy industries conveying large amounts of raw materials, e.g. in steel industry. Some plants also require material transport at high temperatures and velocities, making the need of temperature stable and abrasion resistant wear protection necessary. Various types and wear behaviour of ceramic protection are known. Hence, the goal of this study is to identify the best suitable ceramic materials for abrasive conditions in harsh environments at temperatures up to 950°C and severe thermal gradients. Chamottes, known for their excellent thermal shock resistance are compared to high abrasion resistant ceramic wear tiles and a cost efficient cement-bounded hard compound. Testing was done under high-stress three-body abrasion regime with a modified ASTM G65 apparatus enabling for investigations up to ~950°C. Thereto heated abrasive is introduced into the wear track and also preheated ceramic samples were used and compared to ambient temperature experiments. Results indicate a significant temperature influence on chamottes and the hard compound. While the chamottes benefit from temperature increase, the cement-bounded hard compound showed its limitation at abrasive temperatures of 950°C. The high abrasion resistant wear tiles represented the materials with the best wear resistance and less temperature influence in the investigated range.

Incorporation of gypsum waste in ceramic block production: Proposal for a minimal battery of tests to evaluate technical and environmental viability of this recycling process.

PubMed

Godinho-Castro, Alcione P; Testolin, Renan C; Janke, Leandro; Corrêa, Albertina X R; Radetski, Claudemir M

2012-01-01

Civil engineering-related construction and demolition debris is an important source of waste disposed of in municipal solid waste landfills. After clay materials, gypsum waste is the second largest contributor to the residential construction waste stream. As demand for sustainable building practices grows, interest in recovering gypsum waste from construction and demolition debris is increasing, but there is a lack of standardized tests to evaluate the technical and environmental viability of this solid waste recycling process. By recycling gypsum waste, natural deposits of gypsum might be conserved and high amounts of the waste by-product could be reused in the civil construction industry. In this context, this paper investigates a physical property (i.e., resistance to axial compression), the chemical composition and the ecotoxicological potential of ceramic blocks constructed with different proportions of clay, cement and gypsum waste, and assesses the feasibility of using a minimal battery of tests to evaluate the viability of this recycling process. Consideration of the results for the resistance to axial compression tests together with production costs revealed that the best formulation was 35% of plastic clay, 35% of non-plastic clay, 10% of Portland cement and 20% of gypsum waste, which showed a mean resistance of 4.64MPa. Energy dispersive X-ray spectrometry showed calcium and sulfur to be the main elements, while quartz, gypsum, ettringite and nacrite were the main crystalline compounds found in this formulation. Ecotoxicity tests showed that leachate from this formulation is weakly toxic toward daphnids and bacteria (EC(20%)=69.0 and 75.0, respectively), while for algae and fish the leachate samples were not toxic at the EC(50%) level. Overall, these results show that the addition of 20% of gypsum waste to the ceramic blocks could provide a viable substitute for clay in the ceramics industry and the tests applied in this study proved to be a useful tool

Indentation Behavior and Mechanical Properties of Tungsten/Chromium co-Doped Bismuth Titanate Ceramics Sintered at Different Temperatures

PubMed Central

Xu, Jiageng; Chen, Yu; Tan, Zhi; Nie, Rui; Wang, Qingyuan; Zhu, Jianguo

2018-01-01

A sort of tungsten/chromium(W/Cr) co-doped bismuth titanate (BIT) ceramics (Bi4Ti2.95W0.05O12.05 + 0.2 wt % Cr2O3, abbreviate to BTWC) are ordinarily sintered between 1050 and 1150 °C, and the indentation behavior and mechanical properties of ceramics sintered at different temperatures have been investigated by both nanoindentation and microindentation technology. Firstly, more or less Bi2Ti2O7 grains as the second phase were found in BTWC ceramics, and the grain size of ceramics increased with increase of sintering temperatures. A nanoindentation test for BTWC ceramics reveals that the testing hardness of ceramics decreased with increase of sintering temperatures, which could be explained by the Hall–Petch equation, and the true hardness could be calculated according to the pressure-state-response (PSR) model considering the indentation size effect, where the value of hardness depends on the magnitude of load. While, under the application of microsized Vickers, the sample sintered at a lower temperature (1050 °C) gained four linearly propagating cracks, however, they were observed to shorten in the sample sintered at a higher temperature (1125 °C). Moreover, both the crack deflection and the crack branching existed in the latter. The hardness and the fracture toughness of BTWC ceramics presented a contrary variational tendency with increase of sintering temperatures. A high sintering tends to get a lower hardness and a higher fracture toughness, which could be attributed to the easier plastic deformation and the stronger crack inhibition of coarse grains, respectively, as well as the toughening effect coming from the second phase. PMID:29584677

Strategic Minimization of High Level Waste from Pyroprocessing of Spent Nuclear Fuel

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

Simpson, Michael F.; Benedict, Robert W.

The pyroprocessing of spent nuclear fuel results in two high-level waste streams--ceramic and metal waste. Ceramic waste contains active metal fission product-loaded salt from the electrorefining, while the metal waste contains cladding hulls and undissolved noble metals. While pyroprocessing was successfully demonstrated for treatment of spent fuel from Experimental Breeder Reactor-II in 1999, it was done so without a specific objective to minimize high-level waste generation. The ceramic waste process uses “throw-away” technology that is not optimized with respect to volume of waste generated. In looking past treatment of EBR-II fuel, it is critical to minimize waste generation for technologymore » developed under the Global Nuclear Energy Partnership (GNEP). While the metal waste cannot be readily reduced, there are viable routes towards minimizing the ceramic waste. Fission products that generate high amounts of heat, such as Cs and Sr, can be separated from other active metal fission products and placed into short-term, shallow disposal. The remaining active metal fission products can be concentrated into the ceramic waste form using an ion exchange process. It has been estimated that ion exchange can reduce ceramic high-level waste quantities by as much as a factor of 3 relative to throw-away technology.« less

Computational and experimental study of atmospheric moisture in ceramic blocks filled with waste fibres in winter season

NASA Astrophysics Data System (ADS)

Stastnik, S.

2016-06-01

Development of materials for vertical outer building structures tends to application of hollow clay blocks filled with some appropriate insulation material. Ceramic fittings provide high thermal resistance, but the walls built from them suffer from condensation of air humidity in winter season frequently. The paper presents the computational simulation and experimental laboratory validation of moisture behaviour of such masonry with insulation prepared from waste fibres under the Central European climatic conditions.

Ageing of a phosphate ceramic used to immobilize chloride contaminated actinide waste

NASA Astrophysics Data System (ADS)

Metcalfe, B. L.; Donald, I. W.; Fong, S. K.; Gerrard, L. A.; Strachan, D. M.; Scheele, R. D.

2009-03-01

A process for the immobilization of intermediate level waste containing a significant quantity of chloride using Ca3(PO4)2 as the host material has been developed. Waste ions are incorporated into two phosphate-based phases, chlorapatite [Ca5(PO4)3Cl] and spodiosite [Ca2(PO4)Cl]. Non-active trials performed using Sm as the actinide surrogate demonstrated the durability of these phases in aqueous solution. Trials of the process, in which actinide-doped materials were used, were performed at PNNL which confirmed the wasteform resistant to aqueous leaching. Initial leach trials conducted on 239Pu/241Am loaded ceramic at 313 K/28 days gave normalized mass losses of 1.2 × 10-5 g m-2 and 2.7 × 10-3 g m-2 for Pu and Cl, respectively. In order to assess the response of the phases to radiation-induced damage, accelerated ageing trials were performed on samples in which the 239Pu was replaced with 238Pu. No changes to the crystalline structure of the waste were detected in the XRD spectra after the samples had experienced an α radiation fluence of 4 × 1018 g-1. Leach trials showed that there was an increase in the P and Ca release rates but no change in the Pu release rate.

Ageing of a phosphate ceramic used to immobilize chloride contaminated actinide waste

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

Metcalfe, Brian L.; Donald, Ian W.; Fong, Shirley K.

2009-03-31

AWE has developed a process for the immobilization of ILW waste containing a significant quantity of chloride using Ca3(PO4)2 as the host material. Waste ions are incorporated into two phosphate based phases, chlorapatite, Ca5(PO4)3Cl, and spodiosite, Ca2(PO4)Cl. Non-active trials performed at AWE using samarium as the actinide surrogate demonstrated the durability of these phases in aqueous solution. Trials of the process using actinide-doped material were performed at PNNL which confirmed the immobilized wasteform resistant to aqueous leaching. Initial leach trials conducted on 239Pu /241Am loaded ceramic at 40°C/28 days gave normalized mass losses of 1.2 x 10-5 g.m-2 and 2.7more » x 10-3 g.m-2 for Pu and Cl respectively. In order to assess the response of the phases to radiation-induced damage, accelerated ageing trials were performed on samples in which the 239Pu was replaced by 238Pu. No changes to the crystalline structure of the waste were detected using XRD after the samples had experienced a radiation dose of 4 x 1018 α.g-1. Leach trials showed that there had been an increase in the P and Ca release rates but no change in the Pu release rate.« less

Nuclear fuel cycle waste stream immobilization with cermets for improved thermal properties and waste consolidation

NASA Astrophysics Data System (ADS)

Ortega, Luis H.; Kaminski, Michael D.; Zeng, Zuotao; Cunnane, James

2013-07-01

In the pursuit of methods to improve nuclear waste form thermal properties and combine potential nuclear fuel cycle wastes, a bronze alloy was combined with an alkali, alkaline earth metal bearing ceramic to form a cermet. The alloy was prepared from copper and tin (10 mass%) powders. Pre-sintered ceramic consisting of cesium, strontium, barium and rubidium alumino-silicates was mixed with unalloyed bronze precursor powders and cold pressed to 300 × 103 kPa, then sintered at 600 °C and 800 °C under hydrogen. Cermets were also prepared that incorporated molybdenum, which has a limited solubility in glass, under similar conditions. The cermet thermal conductivities were seven times that of the ceramic alone. These improved thermal properties can reduce thermal gradients within the waste forms thus lowering internal temperature gradients and thermal stresses, allowing for larger waste forms and higher waste loadings. These benefits can reduce the total number of waste packages necessary to immobilize a given amount of high level waste and immobilize troublesome elements.

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.

Bioactive calcium silicate ceramics and coatings.

PubMed

Liu, Xuanyong; Morra, Marco; Carpi, Angelo; Li, Baoe

2008-10-01

CaO-SiO2 based ceramics have been regarded as potential candidates for artificial bone due to their excellent bone bioactivity and biocompatibility. However, they cannot be used as implants under a heavy load because of their poor mechanical properties, in particular low fracture toughness. Plasma spraying CaO-SiO2 based ceramic coatings onto titanium alloys can expand their application to the hard tissue replacement under a heavy load. Plasma sprayed wollastonite, dicalcium silicate and diopside coatings have excellent bone bioactivity and high bonding strength to titanium alloys. It is possible that these plasma sprayed CaO-SiO2 based ceramic coatings will be applied in clinic after they are widely and systematically researched.

Wear characteristics of current aesthetic dental restorative CAD/CAM materials: two-body wear, gloss retention, roughness and Martens hardness.

PubMed

Mörmann, Werner H; Stawarczyk, Bogna; Ender, Andreas; Sener, Beatrice; Attin, Thomas; Mehl, Albert

2013-04-01

This study determined the two-body wear and toothbrushing wear parameters, including gloss and roughness measurements and additionally Martens hardness, of nine aesthetic CAD/CAM materials, one direct resin-based nanocomposite plus that of human enamel as a control group. Two-body wear was investigated in a computer-controlled chewing simulator (1.2 million loadings, 49N at 1.7Hz; 3000 thermocycles 5/50°C). Each of the 11 groups consisted of 12 specimens and 12 enamel antagonists. Quantitative analysis of wear was carried out with a 3D-surface analyser. Gloss and roughness measurements were evaluated using a glossmeter and an inductive surface profilometer before and after abrasive toothbrushing of machine-polished specimens. Additionally Martens hardness was measured. Statistically significant differences were calculated with one-way ANOVA (analysis of variance). Statistically significant differences were found for two-body wear, gloss, surface roughness and hardness. Zirconium dioxide ceramics showed no material wear and low wear of the enamel antagonist. Two-body wear of CAD/CAM-silicate and -lithium disilicate ceramics, -hybrid ceramics and -nanocomposite as well as direct nanocomposite did not differ significantly from that of human enamel. Temporary polymers showed significantly higher material wear than permanent materials. Abrasive toothbrushing significantly reduced gloss and increased roughness of all materials except zirconium dioxide ceramics. Gloss retention was highest with zirconium dioxide ceramics, silicate ceramics, hybrid ceramics and nanocomposites. Temporary polymers showed least gloss retention. Martens hardness differed significantly among ceramics, between ceramics and composites, and between resin composites and acrylic block materials as well. All permanent aesthetic CAD/CAM block materials tested behave similarly or better with respect to two-body wear and toothbrushing wear than human enamel, which is not true for temporary polymer CAD

A U-bearing composite waste form for electrochemical processing wastes

NASA Astrophysics Data System (ADS)

Chen, X.; Ebert, W. L.; Indacochea, J. E.

2018-04-01

Metallic/ceramic composite waste forms are being developed to immobilize combined metallic and oxide waste streams generated during electrochemical recycling of used nuclear fuel. Composites were made for corrosion testing by reacting HT9 steel to represent fuel cladding, Zr and Mo to simulate metallic fuel waste, and a mixture of ZrO2, Nd2O3, and UO2 to represent oxide wastes. More than half of the added UO2 was reduced to metal and formed Fe-Zr-U intermetallics and most of the remaining UO2 and all of the Nd2O3 reacted to form zirconates. Fe-Cr-Mo intermetallics were also formed. Microstructure characterization of the intermetallic and ceramic phases that were generated and tests conducted to evaluate their corrosion behaviors indicate composite waste forms can accommodate both metallic and oxidized waste streams in durable host phases.

Advanced ceramic materials for next-generation nuclear applications

NASA Astrophysics Data System (ADS)

Marra, John

2011-10-01

The nuclear industry is at the eye of a 'perfect storm' with fuel oil and natural gas prices near record highs, worldwide energy demands increasing at an alarming rate, and increased concerns about greenhouse gas (GHG) emissions that have caused many to look negatively at long-term use of fossil fuels. This convergence of factors has led to a growing interest in revitalization of the nuclear power industry within the United States and across the globe. Many are surprised to learn that nuclear power provides approximately 20% of the electrical power in the US and approximately 16% of the world-wide electric power. With the above factors in mind, world-wide over 130 new reactor projects are being considered with approximately 25 new permit applications in the US. Materials have long played a very important role in the nuclear industry with applications throughout the entire fuel cycle; from fuel fabrication to waste stabilization. As the international community begins to look at advanced reactor systems and fuel cycles that minimize waste and increase proliferation resistance, materials will play an even larger role. Many of the advanced reactor concepts being evaluated operate at high-temperature requiring the use of durable, heat-resistant materials. Advanced metallic and ceramic fuels are being investigated for a variety of Generation IV reactor concepts. These include the traditional TRISO-coated particles, advanced alloy fuels for 'deep-burn' applications, as well as advanced inert-matrix fuels. In order to minimize wastes and legacy materials, a number of fuel reprocessing operations are being investigated. Advanced materials continue to provide a vital contribution in 'closing the fuel cycle' by stabilization of associated low-level and high-level wastes in highly durable cements, ceramics, and glasses. Beyond this fission energy application, fusion energy will demand advanced materials capable of withstanding the extreme environments of high

Crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics for immobilization of simulated sulfate bearing high-level liquid waste

NASA Astrophysics Data System (ADS)

Wu, Lang; Xiao, Jizong; Wang, Xin; Teng, Yuancheng; Li, Yuxiang; Liao, Qilong

2018-01-01

The crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics with different content (0-30 wt %) of simulated sulfate bearing high-level liquid waste (HLLW) were evaluated. The sulfate phase segregation in vitrification process was also investigated. The results show that the glass-ceramics with 0-20 wt% of HLLW possess mainly zirconolite phase along with a small amount baddeleyite phase. The amount of perovskite crystals increases while the amount of zirconolite crystals decreases when the HLLW content increases from 20 to 30 wt%. For the samples with 20-30 wt% HLLW, yellow phase was observed during the vitrification process and it disappeared after melting at 1150 °C for 2 h. The viscosity of the sample with 16 wt% HLLW (HLLW-16) is about 27 dPa·s at 1150 °C. The addition of a certain amount (≤20 wt %) of HLLW has no significant change on the aqueous stability of glass-ceramic waste forms. After 28 days, the 90 °C PCT-type normalized leaching rates of Na, B, Si, and La of the sample HLLW-16 are 7.23 × 10-3, 1.57 × 10-3, 8.06 × 10-4, and 1.23 × 10-4 g·m-2·d-1, respectively.

Determining the Effect of Material Hardness During the Hard Turning of AISI4340 Steel

NASA Astrophysics Data System (ADS)

Kambagowni, Venkatasubbaiah; Chitla, Raju; Challa, Suresh

2018-05-01

In the present manufacturing industries hardened steels are most widely used in the applications like tool design and mould design. It enhances the application range of hard turning of hardened steels in manufacturing industries. This study discusses the impact of workpiece hardness, feed and depth of cut on Arithmetic mean roughness (Ra), root mean square roughness (Rq), mean depth of roughness (Rz) and total roughness (Rt) during the hard turning. Experiments have been planned according to the Box-Behnken design and conducted on hardened AISI4340 steel at 45, 50 and 55 HRC with wiper ceramic cutting inserts. Cutting speed is kept constant during this study. The analysis of variance was used to determine the effects of the machining parameters. 3-D response surface plots drawn based on RSM were utilized to set up the input-output relationships. The results indicated that the feed rate has the most significant parameter for Ra, Rq and Rz and hardness has the most critical parameter for the Rt. Further, hardness shows its influence over all the surface roughness characteristics.

Why ceramic engines?

NASA Technical Reports Server (NTRS)

Stadler, H. L.

1984-01-01

Oil is still a problem for the U.S. and its allies. Transportation uses 61 percent of U.S. oil and its share is increasing, so more efficient technology should be concentrated there. Trucks' share of oil use is increasing because they are already much more efficient than autos. The primary truck opportunities are streamlining, more efficient engines, and shifting freight to railroads. More efficient engines are possible using ceramics to allow elimination of cooling systems and better use of waste exhaust heat. A 60 percent improvement seems possible if ceramics can be made tough enough and durable enough.

Formation and corrosion of a 410 SS/ceramic composite

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

Chen, X.; Ebert, W. L.; Indacochea, J. E.

This study evaluates the possible use of alloy/ceramic composite waste forms to immobilize metallic and oxide waste streams generated during the electrochemical reprocessing of spent reactor fuel in a single waste form. A representative composite material AOC410 was made to evaluate the microstructure and corrosion behavior at alloy/ceramic interfaces by reacting 410 stainless steel with Zr, Mo, and a mixture of lanthanide oxides. Essentially all of the Zr reacted with lanthanide oxides to form lanthanide zirconate, which combined with the remaining lanthanide oxides to form a porous ceramic network encapsulated by alloy as a composite puck. Excess alloy formed amore » metal bead on top of the composite. The alloys in the composite and bead were both mixture of martensite grains and ferrite grains with carbide precipitates. FeCrMo intermetallic phases also precipitated in the ferrite grains in the composite part. Ferrite surrounding carbides was sensitized and the least corrosion resistant in electrochemical corrosion tests conducted in an acidic brine electrolyte; ferrite neighboring martensite grains and intermetallics corroded galvanically. The lanthanide oxide domains dissolved chemically, but lanthanide zirconate domains did not dissolve. The presence of oxide phases did not affect corrosion of the neighboring alloy phases. These results suggest the longterm corrosion of a composite waste form can be evaluated by using separate material degradation models for the alloy and ceramic phases.« less

Fabrication and characterization of bioactive glass-ceramic using soda-lime-silica waste glass.

PubMed

Abbasi, Mojtaba; Hashemi, Babak

2014-04-01

Soda-lime-silica waste glass was used to synthesize a bioactive glass-ceramic through solid-state reactions. In comparison with the conventional route, that is, the melt-quenching and subsequent heat treatment, the present work is an economical technique. Structural and thermal properties of the samples were examined by X-ray diffraction (XRD) and differential thermal analysis (DTA). The in vitro test was utilized to assess the bioactivity level of the samples by Hanks' solution as simulated body fluid (SBF). Bioactivity assessment by atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM) was revealed that the samples with smaller amount of crystalline phase had a higher level of bioactivity. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication and characterisation of a novel biomimetic anisotropic ceramic/polymer-infiltrated composite material.

PubMed

Al-Jawoosh, Sara; Ireland, Anthony; Su, Bo

2018-04-10

To fabricate and characterise a novel biomimetic composite material consisting of aligned porous ceramic preforms infiltrated with polymer. Freeze-casting was used to fabricate and control the microstructure and porosity of ceramic preforms, which were subsequently infiltrated with 40-50% by volume UDMA-TEGDMA polymer. The composite materials were then subjected to characterisation, namely density, compression, three-point bend, hardness and fracture toughness testing. Samples were also subjected to scanning electron microscopy and computerised tomography (Micro-CT). Three-dimensional aligned honeycomb-like ceramic structures were produced and full interpenetration of the polymer phase was observed using micro-CT. Depending on the volume fraction of the ceramic preform, the density of the final composite ranged from 2.92 to 3.36g/cm 3 , compressive strength ranged from 206.26 to 253.97MPa, flexural strength from 97.73 to 145.65MPa, hardness ranged from 1.46 to 1.62GPa, and fracture toughness from 3.91 to 4.86MPam 1/2 . Freeze-casting provides a novel method to engineer composite materials with a unique aligned honeycomb-like interpenetrating structure, consisting of two continuous phases, inorganic and organic. There was a correlation between the ceramic fraction and the subsequent, density, strength, hardness and fracture toughness of the composite material. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Synroc-D Type Ceramics Produced by Hot Isostatic Pressing and Cold Crucible Melting for Immobilisation of (Al, U) Rich Nuclear Waste

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

Vance, Eric R.; La Robina, Michael; Li, Huijun

2007-07-01

A synroc-D ceramic consisting mostly of spinel, hollandite, pyrochlore-structured CaUTi{sub 2}O{sub 7}, UO{sub 2}, and Ti-rich regions shows promise for immobilisation of a HLW containing mainly Al and U, together with fission products. Ceramics with virtually zero porosities and waste loadings of 50-60 wt% on an oxide basis were prepared by cold crucible melting (CCM) at {approx}1500 deg. C, and also by subsolidus hot isostatic pressing (HIP) at 1100 deg. C to prevent volatile losses. PCT leaching test values for Cs were < 13 g/L, with all other normalised elemental extractions being well below 1 g/L. (authors)

A U-bearing composite waste form for electrochemical processing wastes

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

Chen, X.; Ebert, W. L.; Indacochea, J. E.

Metallic/ceramic composite waste forms are being developed to immobilize combined metallic and oxide waste streams generated during electrochemical recycling of used nuclear fuel. Composites were made for corrosion testing by reacting HT9 steel to represent fuel cladding, Zr and Mo to simulate metallic fuel waste, and a mixture of ZrO2, Nd2O3, and UO2 to represent oxide wastes. More than half of the added UO2 was reduced to metal and formed Fe-Zr-U intermetallics and most of the remaining UO2 and all of the Nd2O3 reacted to form zirconates. Fe-Cr-Mo intermetallics were also formed. Microstructure characterization of the intermetallic and ceramic phasesmore » that were generated and tests conducted to evaluate their corrosion behaviors indicate composite waste forms can accommodate both metallic and oxidized waste streams in durable host phases. (c) 2018 Elsevier B.V. All rights reserved.« less

Bio-inspired self-shaping ceramics

PubMed Central

Bargardi, Fabio L.; Le Ferrand, Hortense; Libanori, Rafael; Studart, André R.

2016-01-01

Shaping ceramics into complex and intricate geometries using cost-effective processes is desirable in many applications but still remains an open challenge. Inspired by plant seed dispersal units that self-fold on differential swelling, we demonstrate that self-shaping can be implemented in ceramics by programming the material's microstructure to undergo local anisotropic shrinkage during heat treatment. Such microstructural design is achieved by magnetically aligning functionalized ceramic platelets in a liquid ceramic suspension, subsequently consolidated through an established enzyme-catalysed reaction. By fabricating alumina compacts exhibiting bio-inspired bilayer architectures, we achieve deliberate control over shape change during the sintering step. Bending, twisting or combinations of these two basic movements can be successfully programmed to obtain a myriad of complex shapes. The simplicity and the universality of such a bottom-up shaping method makes it attractive for applications that would benefit from low-waste ceramic fabrication, temperature-resistant interlocking structures or unusual geometries not accessible using conventional top–down manufacturing. PMID:28008930

Bio-inspired self-shaping ceramics

NASA Astrophysics Data System (ADS)

Bargardi, Fabio L.; Le Ferrand, Hortense; Libanori, Rafael; Studart, André R.

2016-12-01

Shaping ceramics into complex and intricate geometries using cost-effective processes is desirable in many applications but still remains an open challenge. Inspired by plant seed dispersal units that self-fold on differential swelling, we demonstrate that self-shaping can be implemented in ceramics by programming the material's microstructure to undergo local anisotropic shrinkage during heat treatment. Such microstructural design is achieved by magnetically aligning functionalized ceramic platelets in a liquid ceramic suspension, subsequently consolidated through an established enzyme-catalysed reaction. By fabricating alumina compacts exhibiting bio-inspired bilayer architectures, we achieve deliberate control over shape change during the sintering step. Bending, twisting or combinations of these two basic movements can be successfully programmed to obtain a myriad of complex shapes. The simplicity and the universality of such a bottom-up shaping method makes it attractive for applications that would benefit from low-waste ceramic fabrication, temperature-resistant interlocking structures or unusual geometries not accessible using conventional top-down manufacturing.

Effect of sintering temperature on the microstructure and properties of foamed glass-ceramics prepared from high-titanium blast furnace slag and waste glass

NASA Astrophysics Data System (ADS)

Chen, Chang-hong; Feng, Ke-qin; Zhou, Yu; Zhou, Hong-ling

2017-08-01

Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature (900-1060°C) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060°C. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength (16.64 MPa) among the investigated samples and a relatively low bulk density (0.83 g/cm3), were attained in the case of the foamed glass-ceramics sintered at 1000°C.

[Effect of two-step sintering method on properties of zirconia ceramic].

PubMed

Huang, Hui; Wei, Bin; Zhang, Fu-Qiang; Sun, Jing; Gao, Lian

2008-04-01

To study the influence of two-step sintering method on the sintering property, mechanical properties and microstructure of zirconia ceramic. The nano-size zirconia powder were compacted and divided into two groups, one group for one-step sintering method, another group for two-step sintering method. All samples sintered at different temperature. The relative density, three-bend strength, HV hardness, fracture toughness and microstructure of sintered block were investigated. Two-step sintering method influenced the sintering property and mechanical properties of zirconia ceramic. The maximal relative density was 98.49% at 900 degrees C/1,450 degrees C sintering temperature. There were significant difference of mechanical properties between one-step sintering and two-step sintering, the three-bend strength and fracture toughness declined, hardness increased at two-step sintering. The three-bend strength, HV hardness and fracture toughness reached to maximum value as 1,059.08 MPa +/- 75.24 MPa, 1,377.00 MPa +/- 16.37 MPa and 5.92 MPa x m1/2 +/- 0.37 MPa x m1/2 at 900 degrees C/1,450 degrees C sintering temperature respectively. Microscopy revealed the relationship between the porosity and shapes of grains was correlated to strength of the zirconia ceramics. Despite of the two-step sintering method influences the properties of zirconia, it also is a promising esthetic all-ceramic dental material.

The influences of accelerated aging on mechanical properties of veneering ceramics used for zirconia restorations.

PubMed

Luo, Huinan; Tang, Xuehua; Dong, Zhen; Tang, Hui; Nakamura, Takashi; Yatani, Hirofumi

2016-01-01

This study evaluated the influences of accelerated aging on the mechanical properties of veneering ceramics used for zirconia frameworks. Five different veneering ceramics for zirconia frameworks were used. Twenty specimens were fabricated for each veneering ceramic. All specimens were divided into two groups. One was subjected to accelerated aging and the other was used as a control. Accelerated aging was performed in distilled water for 5 h at 200ºC and 2 atm. The density, open porosity, surface roughness, three-point flexural strength, and Vickers hardness were measured. The results showed that the density, open porosity, and surface roughness of all examined veneering ceramics were changed by the accelerated aging process. Accelerated aging was also found to have a positive effect on strength and a negative effect on the hardness.

Adhesion in ceramics and magnetic media

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1989-01-01

When a ceramic is brought into contact with a metal or a polymeric material such as a magnetic medium, strong bonds form between the materials. For ceramic-to-metal contacts, adhesion and friction are strongly dependent on the ductility of the metals. Hardness of metals plays a much more important role in adhesion and friction than does the surface energy of metals. Adhesion, friction, surface energy, and hardness of a metal are all related to its Young's modulus and shear modulus, which have a marked dependence on the electron configuration of the metal. An increase in shear modulus results in a decrease in area of contact that is greater than the corresponding increase in surface energy (the fond energy) with shear modulus. Consequently, the adhesion and friction decrease with increasing shear modulus. For ceramics in contact with polymeric magnetic tapes, environment is extremely important. For example, a nitrogen environment reduces adhesion and friction when ferrite contacts polymeric tape, whereas a vacuum environment strengthens the ferrite-to-tape adhesion and increases friction. Adhesion and friction are strongly dependent on the particle loading of the tape. An increase in magnetic particle concentration increases the complex modulus of the tape, and a lower real area of contact and lower friction result.

Aluminum phosphate ceramics for waste storage

DOEpatents

Wagh, Arun; Maloney, Martin D

2014-06-03

The present disclosure describes solid waste forms and methods of processing waste. In one particular implementation, the invention provides a method of processing waste that may be particularly suitable for processing hazardous waste. In this method, a waste component is combined with an aluminum oxide and an acidic phosphate component in a slurry. A molar ratio of aluminum to phosphorus in the slurry is greater than one. Water in the slurry may be evaporated while mixing the slurry at a temperature of about 140-200.degree. C. The mixed slurry may be allowed to cure into a solid waste form. This solid waste form includes an anhydrous aluminum phosphate with at least a residual portion of the waste component bound therein.

Formation and corrosion of a 410 SS/ceramic composite

NASA Astrophysics Data System (ADS)

Chen, X.; Ebert, W. L.; Indacochea, J. E.

2016-11-01

This study addressed the possible use of alloy/ceramic composite waste forms to immobilize metallic and oxide waste streams generated during the electrochemical reprocessing of spent reactor fuel using a single waste form. A representative composite material was made to evaluate the microstructure and corrosion behavior at alloy/ceramic interfaces by reacting 410 stainless steel with Zr, Mo, and a mixture of lanthanide oxides. Essentially all of the available Zr reacted with lanthanide oxides to generate lanthanide zirconates, which combined with the unreacted lanthanide oxides to form a porous ceramic network that filled with alloy to produce a composite puck. Alloy present in excess of the pore volume of the ceramic generated a metal bead on top of the puck. The alloys in the composite and forming the bead were both mixtures of martensite grains and ferrite grains bearing carbide precipitates; FeCrMo intermetallic phases also precipitated at ferrite grain boundaries within the composite puck. Micrometer-thick regions of ferrite surrounding the carbides were sensitized and corroded preferentially in electrochemical tests. The lanthanide oxides dissolved chemically, but the lanthanide zirconates did not dissolve and are suitable host phases. The presence of oxide phases did not affect corrosion of the neighboring alloy phases.

Effects of Ceramic Density and Sintering Temperature on the Mechanical Properties of a Novel Polymer-Infiltrated Ceramic-Network Zirconia Dental Restorative (Filling) Material.

PubMed

Li, Weiyan; Sun, Jian

2018-05-10

BACKGROUND Polymer-infiltrated ceramic-network (PICN) dental material is a new and practical development in orthodontics. Sintering is the process of forming a stable solid mass from a powder by heating without melting. The aim of this study was to evaluate the effects of sintering temperature on the mechanical properties of a PICN zirconia dental material. MATERIAL AND METHODS A dense zirconia ceramic and four PICN zirconia dental materials, with varying porosities, were sintered at three different temperatures; 12 PICN zirconia dental materials based on these porous ceramics were prepared, as well as a pure polymer. After the specimen preparation, flexural strength and elastic modulus values were measured using the three-point bending test, and fracture toughness were determined by the single-edge notched beam (SENB) method. The Vickers hardness test method was used with an indentation strength (IS) test. Scanning electron microscopy (SEM) was used to examine the microstructure of the ceramic surface and the fracture surface. RESULTS Mechanical properties of the PICN dental materials, including flexural strength, elastic modulus, fracture toughness, and hardness, were more similar to the properties of natural teeth when compared with traditional dental ceramic materials, and were affected by the density and sintering temperature. SEM showed that the porous ceramic network became cohesive and that the length of cracks in the PICN dental material was reduced. CONCLUSIONS PICN zirconia dental materials were characterized by similar mechanical properties to natural dental tissues, but further studies are required continue to improve the similarities with natural human enamel and dentin.

Effects of Ceramic Density and Sintering Temperature on the Mechanical Properties of a Novel Polymer-Infiltrated Ceramic-Network Zirconia Dental Restorative (Filling) Material

PubMed Central

Li, Weiyan

2018-01-01

Background Polymer-infiltrated ceramic-network (PICN) dental material is a new and practical development in orthodontics. Sintering is the process of forming a stable solid mass from a powder by heating without melting. The aim of this study was to evaluate the effects of sintering temperature on the mechanical properties of a PICN zirconia dental material. Material/Methods A dense zirconia ceramic and four PICN zirconia dental materials, with varying porosities, were sintered at three different temperatures; 12 PICN zirconia dental materials based on these porous ceramics were prepared, as well as a pure polymer. After the specimen preparation, flexural strength and elastic modulus values were measured using the three-point bending test, and fracture toughness were determined by the single-edge notched beam (SENB) method. The Vickers hardness test method was used with an indentation strength (IS) test. Scanning electron microscopy (SEM) was used to examine the microstructure of the ceramic surface and the fracture surface. Results Mechanical properties of the PICN dental materials, including flexural strength, elastic modulus, fracture toughness, and hardness, were more similar to the properties of natural teeth when compared with traditional dental ceramic materials, and were affected by the density and sintering temperature. SEM showed that the porous ceramic network became cohesive and that the length of cracks in the PICN dental material was reduced. Conclusions PICN zirconia dental materials were characterized by similar mechanical properties to natural dental tissues, but further studies are required continue to improve the similarities with natural human enamel and dentin. PMID:29746449

Formation of chemically bonded ceramics with magnesium dihydrogen phosphate binder

DOEpatents

Wagh, Arun S.; Jeong, Seung-Young

2004-08-17

A new method for combining magnesium oxide, MgO, and magnesium dihydrogen phosphate to form an inexpensive compactible ceramic to stabilize very low solubility metal oxides, ashes, swarfs, and other iron or metal-based additives, to create products and waste forms which can be poured or dye cast, and to reinforce and strengthen the ceramics formed by the addition of fibers to the initial ceramic mixture.

Ceramic fibers from Si-B-C polymer precursors

NASA Technical Reports Server (NTRS)

Riccitiello, S. R.; Hsu, M. S.; Chen, T. S.

1993-01-01

Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

Phase-Pure and Multiphase Ceramic Waste Forms: Microstructure Evolution and Cesium Immobilization

NASA Astrophysics Data System (ADS)

Tumurugoti, Priyatham

Efforts of this thesis are directed towards developing ceramic waste forms as a potential replacement for the conventional glass waste forms for the safe immobilization and disposal of nuclear wastes from the legacy weapons programs as well as commercial power production. The body of this work consists of two equal parts with first focused on multiphase waste form containing hollandite as major phase and the later, on single-phase hollandites for Cs incorporation. Part I: Multiphase waste forms:. Hollandite-rich multiphase waste form compositions processed by melt-solidification and spark plasma sintering (SPS) were characterized, compared, and validated for nuclear waste incorporation. Phase identification by X-ray diffraction (XRD) and electron back-scattered diffraction (EBSD) confirm hollandite as the major phase present in these samples along with perovskite, pyrochlore and zirconolite. Distribution of select elements observed by wavelength dispersive spectroscopy (WDS) maps indicate that Cs forms a secondary phase during SPS processing, which is considered undesirable. On the other hand Cs partitioned into hollandite phase in melt-processed samples. Further analysis of hollandite structure in melt-processed composition, by selected area electron diffraction (SAED), reveals ordered arrangement of tunnel ions (Ba/Cs) and vacancies, suggesting efficient Cs incorporation into the lattice. Following the microstructural analysis, the crystallization behavior of the multiphase composition during melt-processing was studied. The phase assemblage and evolution of hollandite, zirconolite, pyrochlore, and perovskite type structures during melt processing were studied using thermal analysis, in-situ XRD, and scanning electron microscopy (SEM). Samples prepared by melting followed by annealing and quenching were analyzed to determine and measure the progression of the phase assemblage. Samples were melted at 1500°C and heat-treated at crystallization temperatures of 1285

Comparative effectiveness of ceramic-on-ceramic implants in stemmed hip replacement: a multinational study of six national and regional registries.

PubMed

Sedrakyan, Art; Graves, Stephen; Bordini, Barbara; Pons, Miquel; Havelin, Leif; Mehle, Susan; Paxton, Elizabeth; Barber, Thomas; Cafri, Guy

2014-12-17

The rapid decline in use of conventional total hip replacement with a large femoral head size and a metal-on-metal bearing surface might lead to increased popularity of ceramic-on-ceramic bearings as another hard-on-hard alternative that allows implantation of a larger head. We sought to address comparative effectiveness of ceramic-on-ceramic and metal-on-HXLPE (highly cross-linked polyethylene) implants by utilizing the distributed health data network of the ICOR (International Consortium of Orthopaedic Registries), an unprecedented collaboration of national and regional registries and the U.S. FDA (Food and Drug Administration). A distributed health data network was developed by the ICOR and used in this study. The data from each registry are standardized and provided at a level of aggregation most suitable for the detailed analysis of interest. The data are combined across registries for comprehensive assessments. The ICOR coordinating center and study steering committee defined the inclusion criteria for this study as total hip arthroplasty performed without cement from 2001 to 2010 in patients forty-five to sixty-four years of age with osteoarthritis. Six national and regional registries (Kaiser Permanente and HealthEast in the U.S., Emilia-Romagna region in Italy, Catalan region in Spain, Norway, and Australia) participated in this study. Multivariate meta-analysis was performed with use of linear mixed models, with survival probability as the unit of analysis. We present the results of the fixed-effects model and include the results of the random-effects model in an appendix. SAS version 9.2 was used for all analyses. We first compared femoral head sizes of >28 mm and ≤28 mm within ceramic-on-ceramic implants and then compared ceramic-on-ceramic with metal-on-HXLPE. A total of 34,985 patients were included; 52% were female. We found a lower risk of revision associated with use of ceramic-on-ceramic implants when a larger head size was used (HR [hazard

Method for producing hard-surfaced tools and machine components

DOEpatents

McHargue, Carl J.

1985-01-01

In one aspect, the invention comprises a method for producing tools and machine components having superhard crystalline-ceramic work surfaces. Broadly, the method comprises two steps: A tool or machine component having a ceramic near-surface region is mounted in ion-implantation apparatus. The region then is implanted with metal ions to form, in the region, a metastable alloy of the ions and said ceramic. The region containing the alloy is characterized by a significant increase in hardness properties, such as microhardness, fracture-toughness, and/or scratch-resistance. The resulting improved article has good thermal stability at temperatures characteristic of typical tool and machine-component uses. The method is relatively simple and reproducible.

Method for producing hard-surfaced tools and machine components

DOEpatents

McHargue, C.J.

1981-10-21

In one aspect, the invention comprises a method for producing tools and machine components having superhard crystalline-ceramic work surfaces. Broadly, the method comprises two steps: a tool or machine component having a ceramic near-surface region is mounted in ion-implantation apparatus. The region then is implanted with metal ions to form, in the region, a metastable alloy of the ions and said ceramic. The region containing the alloy is characterized by a significant increase in hardness properties, such as microhardness, fracture-toughness, and/or scratch-resistance. The resulting improved article has good thermal stability at temperatures characteristic of typical tool and machine-component uses. The method is relatively simple and reproducible.

Abradable dual-density ceramic turbine seal system

NASA Technical Reports Server (NTRS)

Clingman, D. L.; Schechter, B.; Cross, K. R.; Cavanagh, J. R.

1981-01-01

A plasma sprayed dual density ceramic abradable seal system for direct application to the HPT seal shroud of small gas turbine engines. The system concept is based on the thermal barrier coating and depends upon an additional layer of modified density ceramic material adjacent to the gas flow path to provide the desired abradability. This is achieved by codeposition of inert fillers with yttria stabilized zirconia (YSZ) to interrupt the continuity of the zirconia struture. The investigation of a variety of candidate fillers, with hardness values as low as 2 on Moh's scale, led to the conclusion that solid filler materials in combination with a YSZ matrix, regardless of their hardness values, have a propensity for compacting rather than shearing as originally expected. The observed compaction is accompanied by high energy dissipation in the rub interaction, usually resulting in the adhesive transfer of blade material to the stationary seal member. Two YSZ based coating systems which incorported hollow alumino silicate spheres as density reducing agents were surveyed over the entire range of compositions from 100 percent filler to 100 percent YSZ. Abradability and erosion characteristics were determined, hardness and permeability characterized, and engine experience acquired with several system configurations.

Catalysis, nanostructure and macroscopic property triangle in bioactive calcium-containing ceramic systems.

PubMed

Meiszterics, Anikó; Havancsák, Károly; Sinkó, Katalin

2013-04-01

Calcium silicate ceramics are intended for application as long-term implant materials. In the present work, attention was paid to understand the correlations between the nanostructure (aggregate size, crystallinity, porosity) and the macroscopic properties (solubility in water and simulated body fluids, SBF; hardness) varying the chemical composition. Varying the catalyst (from a base to various acids) during the chemical synthesis was shown to significantly impact on the pore size, crystallinity and mechanical properties. The basic catalyst yields the ceramics with the highest mechanical strength. Ammonia used in 1.0 or 10.0 molar ratio results in bulk ceramics with parameters required for a biomedical application, good hardness (180-200 HV) and low solubility (1-3%) in water and in SBF. The fine porosity (~50 nm) and homogeneous amorphous structure induce good mechanical character. Copyright © 2012 Elsevier B.V. All rights reserved.

Microwave processing of a dental ceramic used in computer-aided design/computer-aided manufacturing.

PubMed

Pendola, Martin; Saha, Subrata

2015-01-01

Because of their favorable mechanical properties and natural esthetics, ceramics are widely used in restorative dentistry. The conventional ceramic sintering process required for their use is usually slow, however, and the equipment has an elevated energy consumption. Sintering processes that use microwaves have several advantages compared to regular sintering: shorter processing times, lower energy consumption, and the capacity for volumetric heating. The objective of this study was to test the mechanical properties of a dental ceramic used in computer-aided design/computer-aided manufacturing (CAD/CAM) after the specimens were processed with microwave hybrid sintering. Density, hardness, and bending strength were measured. When ceramic specimens were sintered with microwaves, the processing times were reduced and protocols were simplified. Hardness was improved almost 20% compared to regular sintering, and flexural strength measurements suggested that specimens were approximately 50% stronger than specimens sintered in a conventional system. Microwave hybrid sintering may preserve or improve the mechanical properties of dental ceramics designed for CAD/CAM processing systems, reducing processing and waiting times.

Influences of Light-emitting Diode Illumination Bleaching Technique on Nanohardness of Computer-aided Design and Computer-aided Manufacturing Ceramic Restorative Materials.

PubMed

Juntavee, Niwut; Juntavee, Apa; Saensutthawijit, Phuwiwat

2018-02-01

This study evaluated the effect of light-emitting diode (LED) illumination bleaching technique on the surface nanohardness of various computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic materials. Twenty disk-shaped samples (width, length, and thickness = 10, 15, and 2 mm) were prepared from each of the ceramic materials for CAD/CAM, including Lava™ Ultimate (L V ), Vita Enamic® (E n ) IPS e.max® CAD (M e ), inCoris® TZI (I C ), and Prettau® zirconia (P r ). The samples from each type of ceramic were randomly divided into two groups based on the different bleaching techniques to be used on them, using 35% hydrogen peroxide with and without LED illumination. The ceramic disk samples were bleached according to the manufacturer's instruction. Surface hardness test was performed before and after bleaching using nanohardness tester with a Berkovich diamond indenter. The respective Vickers hardness number upon no bleaching and bleaching without or with LED illumination [mean ± standard deviation (SD)] for each type of ceramic were as follows: 102.52 ± 2.09, 101.04 ± 1.18, and 98.17 ± 1.15 for L V groups; 274.96 ± 5.41, 271.29 ± 5.94, and 268.20 ± 7.02 for E n groups; 640.74 ± 31.02, 631.70 ± 22.38, and 582.32 ± 33.88 for M e groups; 1,442.09 ± 35.07, 1,431.32 ± 28.80, and 1,336.51 ± 34.03 for I C groups; and 1,383.82 ± 33.87, 1,343.51 ± 38.75, and 1,295.96 ± 31.29 for P r groups. The results indicated surface hardness reduction following the bleaching procedure of varying degrees for different ceramic materials. Analysis of variance (ANOVA) revealed a significant reduction in surface hardness due to the effect of bleaching technique, ceramic material, and the interaction between bleaching technique and ceramic material (p < 0.05). Bleaching resulted in a diminution of the surface hardness of dental ceramic for CAD/CAM. Using 35% hydrogen peroxide bleaching agent with LED illumination exhibited more reduction in surface hardness

Radiation-hard ceramic Resistive Plate Chambers for forward TOF and T0 systems

NASA Astrophysics Data System (ADS)

Akindinov, A.; Dreyer, J.; Fan, X.; Kämpfer, B.; Kiselev, S.; Kotte, R.; Garcia, A. Laso; Malkevich, D.; Naumann, L.; Nedosekin, A.; Plotnikov, V.; Stach, D.; Sultanov, R.; Voloshin, K.

2017-02-01

Resistive Plate Chambers with ceramic electrodes are the main candidates for a use in precise multi-channel timing systems operating in high-radiation conditions. We report the latest R&D results on these detectors aimed to meet the requirements of the forward T0 counter at the CBM experiment. RPC design, gas mixture, limits on the bulk resistivity of ceramic electrodes, efficiency, time resolution, counting rate capabilities and ageing test results are presented.

Serpentinitic waste materials: possible reuses and critical issues

NASA Astrophysics Data System (ADS)

Cavallo, Alessandro

2017-04-01

quarry to quarry, with abundant antigorite (up to 90 wt. %) and olivine (up to 38 wt. %), and variable contents of diopside, chlorite, magnetite, chromite and brucite. The chemical composition reflects the protolith: MgO 35.1 - 42.7 wt. %, SiO2 38.8 - 42.3 wt. %, Fe2O3 7.1 - 8.8 wt. %, Al2O3 0.9 - 2.8 wt. %, CaO 0.2 - 3.1 wt. %, Cr2O3 0.26 - 0.35 wt. %, Ni 1800 - 2100 ppm; little differences can be observed in trace elements. SEM-EDS investigations evidenced little amounts of chrysotile asbestos fibers (generally < 1000 ppm, mean values 200 - 400 ppm), deriving from cracks, fissures and veins of the waste blocks. Very few published studies on the reuse of serpentinitic wastes can be found. Finely ground antigorite-rich materials could be used as filler for plastics (instead of talc), whereas olivine-rich wastes as a reactive fixing carbon dioxide (as carbonates) released during the use of fossil fuels. In the ceramic industry, the most promising target is represented by forsterite and/or high-MgO ceramics and forsterite refractories (with periclase addition), but also by cordierite ceramics (adding kaolin) and high-hardness vitroceramics. The real possibility of an industrial use of serpentinitic materials will require much more experimental work, because no relevant previous studies are available. Special care must be taken to avoid chrysotile asbestos contamination.

Light energy attenuation through orthodontic ceramic brackets at different irradiation times.

PubMed

Santini, Ario; Tiu, Szu Hui; McGuinness, Niall J P; Aldossary, Mohammed Saeed

2016-09-01

To evaluate the total light energy (TLE) transmission through three types of ceramic brackets with, bracket alone and with the addition of orthodontic adhesive, at different exposure durations, and to compare the microhardness of the cured adhesive. Three different makes of ceramic brackets, Pure Sapphire(M), Clarity™ ADVANCED(P) and Dual Ceramic(P) were used. Eighteen specimens of each make were prepared and allocated to three groups (n = 6). MARC(®)-resin calibrator was used to determine the light curing unit (LCU) tip irradiance (mW/cm(2)) and TLE (J/cm(2)) transmitted through the ceramic brackets, and through ceramic bracket plus Transbond™ XT Light Cure Adhesive, for 5, 10 and 20 s. Vickers-hardness values at the bottom of the cured adhesive were determined. Statistical analysis used one-way analysis of variance (ANOVA); P = 0.05. TLE transmission rose significantly among all samples with increasing exposure durations. TLE reaching the adhesive- enamel interface was less than 10 J/cm(2), and through monocrystalline and polycrystalline ceramic brackets was significantly different (P < 0.05). Pure Sapphire(M) showed the highest amount of TLE transmission and Vickers-hardness values for 5, 10 and 20 s. Following manufacturer's recommendations, insufficient TLE may be delivered to the adhesive: increasing the exposure durations may be required when adhesive is cured through ceramic brackets. Clinicians are advised to measure the tip irradiance of their LCUs and increase curing time beyond 5 s. Orthodontic clinicians should understand the type of light curing device and the orthodontic adhesive used in their practice.

Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

NASA Astrophysics Data System (ADS)

Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

2015-01-01

The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti-6Al-4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO2, anatase TiO2, and a large amount of Al2TiO5. The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle.

The development of Zirconia and Copper toughened Alumina ceramic insert

NASA Astrophysics Data System (ADS)

Amalina Sabuan, Nur; Zolkafli, Nurfatini; Mebrahitom, A.; Azhari, Azmir; Mamat, Othman

2018-04-01

Ceramic cutting tools have been utilized in industry for over a century for its productivity and efficiency in machine tools and cutting tool material. However, due to the brittleness property the application has been limited. In order to manufacture high strength ceramic cutting tools, there is a need for suitable reinforcement to improve its toughness. In this case, copper (Cu) and zirconia (ZrO2) powders were added to investigate the hardness and physical properties of the developed composite insert. A uniaxial pre-forming process of the mix powder was done prior to densification by sintering at 1000 and 1300°C. The effect of the composition of the reinforcement on the hardness, density, shrinkage and microstructure of the inserts was investigated. It was found that an optimum density of 3.26 % and hardness 1385HV was obtained for composite of 10wt % zirconia and 10wt% copper at temperature 1000 °C.

Property-process relations in simulated clinical abrasive adjusting of dental ceramics.

PubMed

Yin, Ling

2012-12-01

This paper reports on property-process correlations in simulated clinical abrasive adjusting of a wide range of dental restorative ceramics using a dental handpiece and diamond burs. The seven materials studied included four mica-containing glass ceramics, a feldspathic porcelain, a glass-infiltrated alumina, and a yttria-stabilized tetragonal zirconia. The abrasive adjusting process was conducted under simulated clinical conditions using diamond burs and a clinical dental handpiece. An attempt was made to establish correlations between process characteristics in terms of removal rate, chipping damage, and surface finish and material mechanical properties of hardness, fracture toughness and Young's modulus. The results show that the removal rate is mainly a function of hardness, which decreases nonlinearly with hardness. No correlations were noted between the removal rates and the complex relations of hardness, Young's modulus and fracture toughness. Surface roughness was primarily a linear function of diamond grit size and was relatively independent of materials. Chipping damage in terms of the average chipping width decreased with fracture toughness except for glass-infiltrated alumina. It also had higher linear correlations with critical strain energy release rates (R²=0.66) and brittleness (R²=0.62) and a lower linear correlation with indices of brittleness (R²=0.32). Implications of these results can provide guidance for the microstructural design of dental ceramics, optimize performance, and guide the proper selection of technical parameters in clinical abrasive adjusting conducted by dental practitioners. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mercury stabilization in chemically bonded phosphate ceramics

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

Wagh, A. S.; Singh, D.; Jeong, S. Y.

2000-04-04

Mercury stabilization and solidification is a significant challenge for conventional stabilization technologies. This is because of the stringent regulatory limits on leaching of its stabilized products. In a conventional cement stabilization process, Hg is converted at high pH to its hydroxide, which is not a very insoluble compound; hence the preferred route for Hg sulfidation to convert it into insoluble cinnabar (HgS). Unfortunately, efficient formation of this compound is pH-dependent. At a high pH, one obtains a more soluble Hg sulfate, in a very low pH range, insufficient immobilization occurs because of the escape of hydrogen sulfide, while efficient formationmore » of HgS occurs only in a moderately acidic region. Thus, the pH range of 4 to 8 is where stabilization with Chemically Bonded Phosphate Ceramics (CBPC) is carried out. This paper discusses the authors experience on bench-scale stabilization of various US Department of Energy (DOE) waste streams containing Hg in the CBPC process. This process was developed to treat DOE's mixed waste streams. It is a room-temperature-setting process based on an acid-base reaction between magnesium oxide and monopotassium phosphate solution that forms a dense ceramic within hours. For Hg stabilization, addition of a small amount (< 1 wt.%) of Na{sub 2}S or K{sub 2}S is sufficient in the binder composition. Here the Toxicity Characteristic Leaching Procedure (TCLP) results on CBPC waste forms of surrogate waste streams representing secondary Hg containing wastes such as combustion residues and Delphi DETOX{trademark} residues are presented. The results show that although the current limit on leaching of Hg is 0.2 mg/L, the results from the CBPC waste forms are at least one order lower than this stringent limit. Encouraged by these results on surrogate wastes, they treated actual low-level Hg-containing mixed waste from their facility at Idaho. TCLP results on this waste are presented here. The efficient

Machinable glass-ceramics forming as a restorative dental material.

PubMed

Chaysuwan, Duangrudee; Sirinukunwattana, Krongkarn; Kanchanatawewat, Kanchana; Heness, Greg; Yamashita, Kimihiro

2011-01-01

MgO, SiO(2), Al(2)O(3), MgF(2), CaF(2), CaCO(3), SrCO(3), and P(2)O(5) were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhardness. Three-point bending strength and fracture toughness were applied by UTM according to ISO 6872: 1997(E). XRD showed that the glass crystallized at 892°C (second crystallization temperature+20°C) for 3 hrs consisted mainly of calcium-mica and fluorapatite crystalline phases. Average hardness (3.70 GPa) closely matched human enamel (3.20 GPa). The higher fracture toughness (2.04 MPa√m) combined with the hardness to give a lower brittleness index (1.81 µm(-1/2)) which indicates that they have exceptional machinability. Bending strength results (176.61 MPa) were analyzed by Weibull analysis to determine modulus value (m=17.80). Machinability of the calcium mica-fluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM.

Elemental Composition of the Powder Particles Produced by Electric Discharge Dispersion of the Wastes of a VK8 Hard Alloy

NASA Astrophysics Data System (ADS)

Latypov, R. A.; Ageev, E. V.; Latypova, G. R.; Altukhov, A. Yu.; Ageeva, E. V.

2017-12-01

The powder fabricated by electric discharge dispersion of the wastes of a VK8 hard alloy is studied by electron-probe microanalysis. This powder formed by electric discharge dispersion in kerosene mainly contains tungsten and carbon and has low contents of oxygen, cobalt, and iron.

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.

Effect of ceramic thickness and shade on mechanical properties of a resin luting agent.

PubMed

Passos, Sheila Pestana; Kimpara, Estevão Tomomitsu; Bottino, Marco Antonio; Rizkalla, Amin S; Santos, Gildo Coelho

2014-08-01

This study aimed to investigate the influence of ceramic thickness and shade on the Knoop hardness and dynamic elastic modulus of a dual-cured resin cement. Six ceramic shades (Bleaching, A1, A2, A3, A3.5, B3) and two ceramic thicknesses (1 mm, 3 mm) were evaluated. Disk specimens (diameter: 7 mm; thickness: 2 mm) of the resin cement were light cured under a ceramic block. Light-cured specimens without the ceramic block at distances of 1 and 3 mm were also produced. The Knoop hardness number (KHN), density, and dynamic Young's moduli were determined. Statistical analysis was conducted using ANOVA and a Tukey B rank order test (p = 0.05). The bleaching 1-mm-thick group exhibited significantly higher dynamic Young's modulus. Lower dynamic Young's moduli were observed for the 3-mm-thick ceramic groups compared to bleaching 3-mm-thick group, and no difference was found among the other 3-mm groups. For the KHN, when A3.5 3-mm-thick was used, the KHN was significantly lower than bleaching and A1 1-mm-thick ceramic; however, no difference was exhibited between the thicknesses of the same shade. The dual-cured resin cement studied irradiated through the 1-mm-thick ceramic with the lightest shade (bleaching ceramic) exhibited a better elastic modulus, and there was no effect in KHN of the resin cement when light cured under different ceramic shades and thicknesses (1 and 3 mm), except when the A3.5 3-mm-thick ceramic was used. Variolink II irradiated through ceramic with the lowest chroma exhibited the highest elastic modulus; therefore, the light activation method might not be the same for all clinical situations. © 2014 by the American College of Prosthodontists.

Phase modification and dielectric properties of a cullet-paper ash-kaolin clay-based ceramic

NASA Astrophysics Data System (ADS)

Samah, K. A.; Sahar, M. R.; Yusop, M.; Omar, M. F.

2018-03-01

Novel ceramics from waste material made of ( x) paper ash-(80 - x) cullet-20 kaolin clay (10wt% ≤ x ≤ 30wt%) were successfully synthesized using a conventional solid-state reaction technique. Energy-dispersive X-ray analysis confirmed the presence of Si, Ca, Al, and Fe in the waste material for preparing these ceramics. The influence of the cullet content on the phase structures and the dielectric properties of these ceramics were systematically investigated. The impedance spectra were verified in the range from 1 Hz to 10 MHz at room temperature. The phase of the ceramics was found to primarily consist of wollastonite (CaSiO3), along with minor phases of γ-dicalcium silicate (Ca2SiO4) and quartz (SiO2). The sample with a cullet content of 55wt% possessed the optimum wollastonite structure and exhibited good dielectric properties. An increase of the cullet content beyond 55wt% resulted in a structural change from wollastonite to dicalcium silicate, a decrease in dielectric constant, and an increase in dielectric loss. All experimental results suggested that these novel ceramics from waste are applicable for electronic devices.

The effect of aqueous media on the mechanical properties of fluorapatite-mullite glass-ceramics.

PubMed

Mollazadeh, S; Ajalli, Siamak; Kashi, Tahereh S Jafarzadeh; Yekta, Bijan Eftekhai; Javadpour, Jafar; Jafari, S; Youssefi, Abbas; Fazel, Akbar

2015-11-01

To verify the effects of alternating thermal changes in aqueous media and chemical composition on mechanical properties of apatite-mullite glass-ceramics and to investigate concentration of ions eluted from glass-ceramics in aqueous media. The glass compositions were from SiO2Al2O3P2O5CaOTiO2BaOZrO2CaF2 system. Glass-ceramics were prepared by heat-treating at 1100°C for 3h samples alternately immersed in water at 5 and 60°C. The 3-point bending strength (n=10) were determined using 3×4×25mm/bar and a universal testing machine, at a cross-head speed of 0.1mm/min. Vickers micro hardness were evaluated by applying a total of 15-20 indentations under a 100g load for 30s. Concentrations of ions eluted from glass-ceramics immersed in 60±5°C double distilled water were determined by ion chromatography. The toxicity of glass-ceramics was assessed by seeding the osteosarcoma cells (MG63) on powder for different days and their cell proliferation assessment was investigated by MTT assay. The data were analyzed using one way analysis of variance and the means were compared by Tukey's test (5% significance level). The highest flexural strength and hardness values after thermal changes belonged to TiO2 and ZrO2 containing glass-ceramics which contained lower amount of released ions. BaO containing glass-ceramic and sample with extra amount of silica showed the highest amount of reduction in their mechanical strength values. These additives enhanced the concentration of eluted ions in aqueous media. MTT results showed that glass-ceramics were almost equivalent concerning their in-vitro biological behavior. Thermal changes and chemical compositions had significant effects on flexural strength and Vickers micro-hardness values. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effects of body formulation and firing temperature to properties of ceramic tile incorporated with electric arc furnace (EAF) slag waste

NASA Astrophysics Data System (ADS)

Sharif, Nurulakmal Mohd; Lim, Chi Yang; Teo, Pao Ter; Seman, Anasyida Abu

2017-07-01

Significant quantities of sludge and slag are generated as waste materials or by-products from steel industries. One of the by-products is Electric Arc Furnace (EAF) steel slag which consists of oxides such as CaO, Al2O3 and FeO. This makes it possible for slag to partially replace the raw materials in ceramic tile production. In our preliminary assessment of incorporating the EAF slag into ceramic tile, it was revealed that at fixed firing temperature of 1150°C, the tile of composition 40 wt.% EAF slag - 60 wt.% ball clay has comparable properties with commercial ceramic tile. Thus, this current study would focus on effects of body formulation (different weight percentages of K-feldspar and silica) and different firing temperatures to properties of EAF slag added ceramic tile. EAF slag from Southern Steel Berhad (SSB) was crushed into micron size (EAF slag content was 40 wt.%) and milled with ball clay, K-feldspar and silica before compacted and fired at 1125°C and 1150°C. The EAF slag added tile was characterized in terms of water absorption, apparent porosity, bulk density, modulus of rupture (MOR) and phase analysis via X-ray diffraction (XRD). The composition of 40 wt.% EAF slag - 30 wt.% ball clay - 10 wt.% K-feldspar - 20 wt.% silica (10F_20S), fired at 1150°C showed the lowest water absorption, apparent porosity and highest bulk density due to enhancement of densification process during firing. However, the same composition of ceramic tile (10F_20S) had the highest MOR at lower firing temperature of 1125°C, contributed by presence of the highest total amount of anorthite and wollastonite reinforcement crystalline phases (78.40 wt.%) in the tile. Overall, both the water absorption and MOR of all ceramic tiles surpassed the requirement regulated by MS ISO 13006:2014 Standard (Annex G: Dry-pressed ceramic tile with low water absorption, Eb ≤ 0.50 % and minimum MOR of 35 MPa).

Raman microscopic studies of PVD deposited hard ceramic coatings

NASA Astrophysics Data System (ADS)

Constable, Christopher Paul

PVD hard ceramic coatings grown via the combined cathodic arc/unbalance magnetron deposition process were studied using Raman microscopy. Characteristic spectra from binary, multicomponent, multilayered and superlattice coatings were acquired to gain knowledge of the solid-state physics associated with Raman scattering from polycrystalline PVD coatings and to compile a comprehensive spectral database. Defect-induced first order scattering mechanisms were observed which gave rise to two pronounced groups of bands related to the acoustical (150-300cm[-1]) and optical (400-750cm[-1]) parts of the phonon spectrum. Evidence was gathered to support the theory that the optic modes were mainly due to the vibrations of the lighter elements and the acoustic modes due to the vibrations of the heavier elements within the lattice.A study into the deformation and disordering on the Raman spectral bands of PVD coatings was performed. TiAIN and TiZrN coatings were intentionally damaged via scratching methods. These scratches were then analysed by Raman mapping, both across and along, and a detailed spectral interpretation performed. Band broadening occurred which was related to "phonon relaxation mechanisms" as a direct result of the breaking up of coating grains resulting in a larger proportion of grain boundaries per-unit-volume. A direct correlation of the amount of damage with band width was observed. Band shifts were also found to occur which were due to the stresses caused by the scratching process. These shifts were found to be the largest at the edges of scratches. The Raman mapping of "droplets", a defect inherent to PVD deposition processes, found that higher compressive stresses and large amounts of disorder occurred for coating growth onto droplets.Strategies designed to evaluate the ability of Raman microscopy to monitor the extent of real wear on cutting tools were evaluated. The removal of a coating layer and subsequent detection of a base layer proved successful

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.

Adsorption of gold ions from industrial wastewater using activated carbon derived from hard shell of apricot stones - an agricultural waste.

PubMed

Soleimani, Mansooreh; Kaghazchi, Tahereh

2008-09-01

In this study, hard shell of apricot stones was selected from agricultural solid wastes to prepare effective and low cost adsorbent for the gold separation from gold-plating wastewater. Different adsorption parameters like adsorbent dose, particle size of activated carbon, pH and agitation speed of mixing on the gold adsorption were studied. The results showed that under the optimum operating conditions, more than 98% of gold was adsorbed onto activated carbon after only 3h. The equilibrium adsorption data were well described by the Freundlich and Langmuir isotherms. Isotherms have been used to obtain thermodynamic parameters. Gold desorption studies were performed with aqueous solution mixture of sodium hydroxide and organic solvents at ambient temperatures. Quantitative recovery of gold ions is possible by this method. As hard shell of apricot stones is a discarded as waste from agricultural and food industries, the prepared activated carbon is expected to be an economical product for gold ion recovery from wastewater.

Characterization of humidity-controlling porous ceramics produced from coal fly ash and waste catalyst by co-sintering

NASA Astrophysics Data System (ADS)

Lin, Kae-Long; Ma, Chih-Ming; Lo, Kang-Wei; Cheng, Ta-Wui

2018-04-01

In this study, the following operating conditions were applied to develop humidity-controlling porous ceramic (HCPC) products: sintering temperatures of 800-1000 °C and percentages of coal fly ash in waste catalyst of 0%-40%. The HCPC samples then underwent a flexural strength test, to determine their quality according to the Chinese National Standards (CNS 3298). Their microstructures, crystal structures, and pore volume were determined in terms of equilibrium moisture content, water vapor adsorption/desorption, and hygroscopic sorption properties over 48 h. Nitrogen adsorption/desorption isotherms showed a hydrophobic behavior (type H3 isotherm). The water vapor adsorption/desorption and hygroscopic sorption properties satisfied the JIS A1470 intensity specification for building materials (>29 g/m2). At sintering temperatures of 950-1000 °C, HCPC samples for coal fly ash containing 20%-30% waste catalyst met the JIS A1470 intensity specifications for building materials (<29 g/m2).

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

Waste disposal package

DOEpatents

Smith, M.J.

1985-06-19

This is a claim for a waste disposal package including an inner or primary canister for containing hazardous and/or radioactive wastes. The primary canister is encapsulated by an outer or secondary barrier formed of a porous ceramic material to control ingress of water to the canister and the release rate of wastes upon breach on the canister. 4 figs.

Additive Manufacturing of Reactive In Situ Zr Based Ultra-High Temperature Ceramic Composites

NASA Astrophysics Data System (ADS)

Sahasrabudhe, Himanshu; Bandyopadhyay, Amit

2016-03-01

Reactive in situ multi-material additive manufacturing of ZrB2-based ultra-high-temperature ceramics in a Zr metal matrix was demonstrated using LENS™. Sound metallurgical bonding was achieved between the Zr metal and Zr-BN composites with Ti6Al4V substrate. Though the feedstock Zr power had α phase, LENS™ processing of the Zr powder and Zr-BN premix powder mixture led to the formation of some β phase of Zr. Microstructure of the Zr-BN composite showed primary grains of zirconium diboride phase in zirconium metal matrix. The presence of ZrB2 ceramic phase was confirmed by X-ray diffraction (XRD) analysis. Hardness of pure Zr was measured as 280 ± 12 HV and, by increasing the BN content in the feedstock, the hardness was found to increase. In Zr-5%BN composite, the hardness was 421 ± 10 HV and the same for Zr-10%BN composite was 562 ± 10 HV. It is envisioned that such multi-materials additive manufacturing will enable products in the future that cannot be manufactured using traditional approaches particularly in the areas of high-temperature metal-ceramic composites with compositional and functional gradation.

Effect of additional materials on the properties of glass-ceramic produced from incinerator fly ashes.

PubMed

Cheng, T W

2004-07-01

There are 21 Metro-waste incinerators in Taiwan under construction and are expected to be finished at year 2003. It is estimated that these incinerators will produce about two million tons of incinerator ash. In order to reduce the volume and eliminate contamination problems, high temperature molten technology studies have been conducted. The purpose of this research was that of trying to control the chemical composition of the glass-ceramic produced from incinerator fly ash, in order to improve the characteristics of the glass-ceramic. The experimental results showed that the additional materials, Mg(OH)2 and waste glass cullet, can change glass-ceramic phases from gehlenite to augite, pigeonite, and diopside. The physical, mechanical and chemical resistance properties of the glass-ceramic also showed much better characteristics than prepared glass-ceramic using incinerator fly ash alone.

Consolidation process for producing ceramic waste forms

DOEpatents

Hash, Harry C.; Hash, Mark C.

2000-01-01

A process for the consolidation and containment of solid or semisolid hazardous waste, which process comprises closing an end of a circular hollow cylinder, filling the cylinder with the hazardous waste, and then cold working the cylinder to reduce its diameter while simultaneously compacting the waste. The open end of the cylinder can be sealed prior to or after the cold working process. The preferred method of cold working is to draw the sealed cylinder containing the hazardous waste through a plurality of dies to simultaneously reduce the diameter of the tube while compacting the waste. This process provides a quick continuous process for consolidating hazardous waste, including radioactive waste.

Layered Manufacturing of Dental Ceramics: Fracture Mechanics, Microstructure, and Elemental Composition of Lithography-Sintered Ceramic.

PubMed

Uçar, Yurdanur; Aysan Meriç, İpek; Ekren, Orhun

2018-02-11

To compare the fracture mechanics, microstructure, and elemental composition of lithography-based ceramic manufacturing with pressing and CAD/CAM. Disc-shaped specimens (16 mm diameter, 1.2 mm thick) were used for mechanical testing (n = 10/group). Biaxial flexural strength of three groups (In-Ceram alumina [ICA], lithography-based alumina, ZirkonZahn) were determined using the "piston on 3-ball" technique as suggested in test Standard ISO-6872. Vickers hardness test was performed. Fracture toughness was calculated using fractography. Results were statistically analyzed using Kruskal-Wallis test followed by Dunnett T3 (α = 0.05). Weibull analysis was conducted. Polished and fracture surface characterization was made using scanning electron microscope (SEM). Energy dispersive spectroscopy (EDS) was used for elemental analysis. Biaxial flexural strength of ICA, LCM alumina (LCMA), and ZirkonZahn were 147 ± 43 MPa, 490 ± 44 MPa, and 709 ± 94 MPa, respectively, and were statistically different (P ≤ 0.05). The Vickers hardness number of ICA was 850 ± 41, whereas hardness values for LCMA and ZirkonZahn were 1581 ± 144 and 1249 ± 57, respectively, and were statistically different (P ≤ 0.05). A statistically significant difference was found between fracture toughness of ICA (2 ± 0.4 MPa⋅m 1/2 ), LCMA (6.5 ± 1.5 MPa⋅m 1/2 ), and ZirkonZahn (7.7 ± 1 MPa⋅m 1/2 ) (P ≤ 0.05). Weibull modulus was highest for LCMA (m = 11.43) followed by ZirkonZahn (m = 8.16) and ICA (m = 5.21). Unlike LCMA and ZirkonZahn groups, a homogeneous microstructure was not observed for ICA. EDS results supported the SEM images. Within the limitations of this in vitro study, it can be concluded that LCM seems to be a promising technique for final ceramic object manufacturing in dental applications. Both the manufacturing method and the material used should be improved. © 2018 by the American College of Prosthodontists.

The nitrate to ammonia and ceramic (NAC) process for the denitration and immobilization of low-level radioactive liquid waste (LLW)

NASA Astrophysics Data System (ADS)

Muguercia, Ivan

Hazardous radioactive liquid waste is the legacy of more than 50 years of plutonium production associated with the United States' nuclear weapons program. It is estimated that more than 245,000 tons of nitrate wastes are stored at facilities such as the single-shell tanks (SST) at the Hanford Site in the state of Washington, and the Melton Valley storage tanks at Oak Ridge National Laboratory (ORNL) in Tennessee. In order to develop an innovative, new technology for the destruction and immobilization of nitrate-based radioactive liquid waste, the United State Department of Energy (DOE) initiated the research project which resulted in the technology known as the Nitrate to Ammonia and Ceramic (NAC) process. However, inasmuch as the nitrate anion is highly mobile and difficult to immobilize, especially in relatively porous cement-based grout which has been used to date as a method for the immobilization of liquid waste, it presents a major obstacle to environmental clean-up initiatives. Thus, in an effort to contribute to the existing body of knowledge and enhance the efficacy of the NAC process, this research involved the experimental measurement of the rheological and heat transfer behaviors of the NAC product slurry and the determination of the optimal operating parameters for the continuous NAC chemical reaction process. Test results indicate that the NAC product slurry exhibits a typical non-Newtonian flow behavior. Correlation equations for the slurry's rheological properties and heat transfer rate in a pipe flow have been developed; these should prove valuable in the design of a full-scale NAC processing plant. The 20-percent slurry exhibited a typical dilatant (shear thickening) behavior and was in the turbulent flow regime due to its lower viscosity. The 40-percent slurry exhibited a typical pseudoplastic (shear thinning) behavior and remained in the laminar flow regime throughout its experimental range. The reactions were found to be more efficient in the

Selective recovery of silver from waste low-temperature co-fired ceramic and valorization through silver nanoparticle synthesis.

PubMed

Swain, Basudev; Shin, Dongyoon; Joo, So Yeong; Ahn, Nak Kyoon; Lee, Chan Gi; Yoon, Jin-Ho

2017-11-01

Considering the value of silver metal and silver nanoparticles, the waste generated during manufacturing of low temperature co-fired ceramic (LTCC) were recycled through the simple yet cost effective process by chemical-metallurgy. Followed by leaching optimization, silver was selectively recovered through precipitation. The precipitated silver chloride was valorized though silver nanoparticle synthesis by a simple one-pot greener synthesis route. Through leaching-precipitation optimization, quantitative selective recovery of silver chloride was achieved, followed by homogeneous pure silver nanoparticle about 100nm size were synthesized. The reported recycling process is a simple process, versatile, easy to implement, requires minimum facilities and no specialty chemicals, through which semiconductor manufacturing industry can treat the waste generated during manufacturing of LTCC and reutilize the valorized silver nanoparticles in manufacturing in a close loop process. Our reported process can address issues like; (i) waste disposal, as well as value-added silver recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of lower the futuristic carbon economy and cradle-to-cradle technology management, simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

The Effect of Surface Treatment on the Knoop Hardness of DICOR

DTIC Science & Technology

1990-01-01

during an AFIT- sponsored program in Dental Materials. 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and Identify by block number...state of DICOR and harder than human enamel. Shaded DICOR had a surface hardness comparable to dental porcelain. The internal glass-ceramic material...THE EFFECT OF SURFACE TREATMENT ON THE KNOOP HARDNESS OF DICOR W.Patrick Naylor, DDS, MPH, MS* Lieutenant Colonel, US Air Force Dental Corps Brooks

Manufacture, characterisation and properties of novel fluorcanasite glass-ceramics.

PubMed

Pollington, Sarah; van Noort, Richard

2012-11-01

The aim of this study was to investigate the manufacture and characterisation of different compositions of fluorcanasite glass-ceramics with reduced fluorine content and to assess their mechanical and physical properties. Three compositional variations (S80, S81 and S82) of a fluorcanasite glass were investigated. Differential thermal analysis (DTA) and X-ray diffraction (XRD) identified crystallisation temperatures and phases. X-ray fluorescence (XRF) determined the element composition in the glass-ceramics. Different heat treatments [2 h nucleation and either 2 or 4 h crystallisation] were used for the glasses. Scanning electron microscopy (SEM) examined the microstructure of the cerammed glass. The chemical solubility, biaxial flexural strength, fracture toughness, hardness and brittleness index of S81 and S82 fluorcanasite were investigated with lithium disilicate (e.max CAD, Ivoclar Vivadent) as a commercial comparison. Statistical analysis was performed using one-way ANOVA with Tukey's multiple comparison tests (P<0.05). Weibull analysis was employed to examine the reliability of the strength data. All compositions successfully produced glasses. XRD analysis confirmed fluorcanasite formation with the S81 and S82 compositions, with the S82 (2+2h) showing the most prominent crystal structure. The chemical solubility of the glass-ceramics was significantly different, varying from 2565 ± 507 μg/cm(2) for the S81 (2+2 h) to 722 ± 177 μg/cm(2) for the S82 (2+2 h) to 37.4 ± 25.2 μg/cm(2) for the lithium disilicate. BFS values were highest for the S82 (2+2 h) composition (250 ± 26 MPa) and lithium disilicate (266 ± 37 MPa) glass-ceramics. The fracture toughness was higher for the S82 compositions, with the S82 (2+2h) attaining the highest value of 4.2 ± 0.3 MPa m(1/2)(P=0.01). The S82 (2+2 h) fluorcanasite glass-ceramic had the lowest brittleness index. The S82 (2+2 h) fluorcanasite glass-ceramic has acceptable chemical solubility, high biaxial flexural

A new methodology to prepare ceramic-organic composite coatings with good cavitation erosion resistance.

PubMed

Deng, Wen; Hou, Guoliang; Li, Shuangjian; Han, Jiesheng; Zhao, Xiaoqin; Liu, Xia; An, Yulong; Zhou, Huidi; Chen, Jianmin

2018-06-01

A simple, scalable and economical method was proposed to obtain ceramic-organic composite coating with excellent comprehensive properties include hardness, toughness, elastic recovery, lamellar interfacial bonding and anti-cavitation erosion: introducing epoxy resin into the pores and micro-cracks of plasma sprayed ceramic coating. The results indicate that the epoxy resin was successfully penetrated into the whole ceramic coating and filled almost all defects by vacuum impregnation, which greatly enhanced its compactness and mechanical properties. The bonding strength between top coating and metal interlayer significantly increased from 17.3 MPa to 53.0 MPa, and the hardness (H) of top coating greatly increased from 11.07 GPa to 23.57 GPa. Besides, the value of H 3 /E 2 also increased from 0.06 GPa to 0.15 GPa, meaning the toughness of ceramic coating had been obviously improved. The pure ceramic coating had been punctured only after 4 h of cavitation test. However, the resin with high elasticity and toughness can effectively absorb impact energy, prevent cracks propagation and delay splats spallation during the cavitation erosion process. The novel composite coating displayed far better cavitation erosion resistance than pure ceramic coating, and it was still intact after 10 h of test. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization of Low Firing Temperature Ceramic Glaze Using Phuket MSW and Soda Lime Cullet

NASA Astrophysics Data System (ADS)

Ketboonruang, P.; Jinawat, S.; Kashima, D. P.; Wasanapiarnpong, T.; Sujaridworakun, P.; Buggakuptav, W.; Traipol, N.; Jiemsirilers, S.

2011-10-01

The normal firing temperature of ceramic products is around 1200 °C. In order to reduce firing temperature, industrial wastes were utilized in ceramic glaze. Phuket municipal solid waste (MSW), soda lime cullet, and borax were used as raw materials for low firing temperature glazes. The glaze compositions were designed using a triaxial diagram. Stoneware ceramic body was glazed then fired at 1000 and 1150 °C for 15 minutes. Morphology and phase composition of glazes were analyzed by Scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Thermal expansion compatibility of Stoneware body and glazes were investigated using a dilatometer. Melting behaviour of selected glaze was analyzed by heating stage microscopy. Phuket MSW and Soda lime glass cullet can be used in high percentage as major raw materials for low firing temperature ceramic glaze that show good texture and vitrified at lower firing temperature without using any commercial ceramic frits. The firing temperature can be reduced up to 150 °C in this study.

The Microstructure and Physical Properties of Incinerated Paper-Cullet-Clay Ceramics

NASA Astrophysics Data System (ADS)

Sahar, M. R.; Hamzah, K.; Rohani, M. S.; Samah, K. A.; Razi, M. M.

A series of ceramic based on (x) incinerated recycle paper - (80-x) cullet - 20 Kaolin clay (where 10×45 wt%) has successfully been made by slip casting technique followed by sintering at 1000 °C. The actual composition of ceramic is analyzed using Energy Dispersive of X-Ray (EDAX) while the phase existence is determined using X-Ray Diffraction (XRD) technique. Their microstructural morphology is observed under Scanning Electron Microscope (SEM) and the physical properties are measured in term of their thermal shrinkage and hardness. It is found that the ceramic contain mostly of Silica and the phase is dominated by the existence of Quartz (SiO2), Wollastonite (CaSiO3) and Anorthite (Ca(Al2SiO8)). The SEM micrograph shows that the morphology is dominated by the existence of granular structure, and then become smoother as the cullet level is further increased. It is also found out that the thermal shrinkage is in the range 18% - 6.5% while the hardness is in the range of 152MPa- 1.463 GPa depending on composition.

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

SELF SINTERING OF RADIOACTIVE WASTES

DOEpatents

McVay, T.N.; Johnson, J.R.; Struxness, E.G.; Morgan, K.Z.

1959-12-29

A method is described for disposal of radioactive liquid waste materials. The wastes are mixed with clays and fluxes to form a ceramic slip and disposed in a thermally insulated container in a layer. The temperature of the layer rises due to conversion of the energy of radioactivity to heat boillng off the liquid to fomn a dry mass. The dry mass is then covered with thermal insulation, and the mass is self-sintered into a leach-resistant ceramic cake by further conversion of the energy of radioactivity to heat.

Liquid-assisted laser ablation of advanced ceramics and glass-ceramic materials

NASA Astrophysics Data System (ADS)

Garcia-Giron, A.; Sola, D.; Peña, J. I.

2016-02-01

In this work, results obtained by laser ablation of advanced ceramics and glass-ceramic materials assisted by liquids are reported. A Q-switched Nd:YAG laser at its fundamental wavelength of 1064 nm with pulse-width in the nanosecond range was used to machine the materials, which were immersed in water and ethylene glycol. Variation in geometrical parameters, morphology, and ablation yields were studied by using the same laser working conditions. It was observed that machined depth and removed volume depended on the thermal, optical, and mechanical features of the processed materials as well as on the properties of the surrounding medium in which the laser processing was carried out. Variation in ablation yields was studied in function of the liquid used to assist the laser process and related to refractive index and viscosity. Material features and working conditions were also related to the obtained results in order to correlate ablation parameters with respect to the hardness of the processed materials.

Chemically bonded phosphate ceramics of trivalent oxides of iron and manganese

DOEpatents

Wagh, Arun S.; Jeong, Seung-Young

2002-01-01

A new method for combining elemental iron and other metals to form an inexpensive ceramic to stabilize arsenic, alkaline red mud wastes, swarfs, and other iron or metal-based additives, to create products and waste forms which can be poured or dye cast.

Piezoelectric ceramic implants: in vivo results.

PubMed

Park, J B; Kelly, B J; Kenner, G H; von Recum, A F; Grether, M F; Coffeen, W W

1981-01-01

The suitability of barium titanate (BaTiO3) ceramic for direct substitution of hard tissues was evaluated using both electrically stimulated (piezoelectric) and inactive (nonpolarized) test implants. Textured cylindrical specimens, half of them made piezoelectric by polarization in a high electric field, were implanted into the cortex of the midshaft region of the femora of dogs for various periods of time. Interfacial healing and bio-compatibility of the implant material were studied using mechanical, microradiographical, and histological techniques. Our results indicate that barium titanate ceramic shows a very high degree of biocompatibility as evidenced by the absence of inflammatory or foreign body reactions at the implant-tissue interface. Furthermore, the material and its surface porosity allowed a high degree of bone ingrowth as evidenced by microradiography and a high degree of interfacial tensile strength. No difference was found between the piezoelectric and the electrically neutral implant-tissue interfaces. Possible reasons for this are discussed. The excellent mechanical properties of barium titanate, its superior biocompatibility, and the ability of bone to form a strong mechanical interfacial bond with it, makes this material a new candidate for further tests for hard tissue replacement.

High hardness in the biocompatible intermetallic compound β-Ti3Au.

PubMed

Svanidze, Eteri; Besara, Tiglet; Ozaydin, M Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M; Morosan, E

2016-07-01

The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti-Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials.

Effect of soldering on the metal-ceramic bond strength of an Ni-Cr base alloy.

PubMed

Nikellis, Ioannis; Levi, Anna; Zinelis, Spiros

2005-11-01

Although soldering is a common laboratory procedure, the use of soldering alloys may adversely affect metal-ceramic bond strength and potentially decrease the longevity of metal-ceramic restorations. The purpose of this study was to investigate the effect of soldering on metal-ceramic bond strength of a representative Ni-Cr base metal alloy. Twenty-eight rectangular (25 x 3 x 0.5 mm) Ni-based alloy (Wiron 99) specimens were equally divided into soldering (S) and reference (R) groups. Soldering group specimens were covered with a 0.1-mm layer of the appropriate solder (Wiron-Lot) and reduced by 0.1 mm on the opposite side. Five specimens of each group were used for the measurement of surface roughness parameter (R(z)) and hardness, and 3 were used for measurement of the modulus of elasticity. Six specimens of each group were covered with porcelain (Ceramco 3) and subjected to a 3-point bending test for evaluation of the metal-ceramic bond strength according to the ISO 9693 specification. The data from surface roughness, hardness, modulus of elasticity, and metal-ceramic bond strength were analyzed statistically, using independent t tests (alpha=.05). Statistical analysis of the R(z) surface roughness parameter (S: 3.4 +/- 0.3 mum; R: 3.7 +/- 0.7 microm; P=.07) and bond strength (S: 46 +/- 3 MPa; R: 40 +/- 5 MPa; P=.057) failed to reveal any significant difference between the 2 groups. The specimens of the soldering group demonstrated significantly lower values both in hardness (S: 128 +/- 11 VHN; R: 217 +/- 4 VHN; P<.001) and in modulus of elasticity (S: 135 +/- 4 GPa; R: 183 +/- 6 GPa; P=.035) than the reference group. Under the conditions of the present study, the addition of solder to the base metal alloy did not affect the metal-ceramic bond strength.

Hardness properties and microscopic investigation of crack- crystal interaction in SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F glass ceramic system.

PubMed

Roy, Shibayan; Basu, Bikramjit

2010-01-01

In view of the potential engineering applications requiring machinability and wear resistance, the present work focuses to evaluate hardness property and to understand the damage behavior of some selected glass-ceramics having different crystal morphologies with SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F composition, using static micro-indentation tests as well as dynamic scratch tests, respectively. Vickers hardness of up to 5.5 GPa has been measured in glass-ceramics containing plate like mica crystals. Scratch tests at a high load of 50 Nin artificial saliva were carried out in order to simulate the crack-microstructure interaction during real-time abrasion wear and machining operation. The experimental observations indicate that the novel "spherulitic-dendritic shaped "crystals, similar to the plate like crystals, have the potential to hinder the scratching induced crack propagation. In particular, such potential of the 'spherulitic-dendritic' crystals become more effective due to the larger interfacial area with the glass matrix as well as the dendritic structure of each mica plate, which helps in crack deflection and crack blunting, to a larger extent.While modest damage tolerant behavior is observed in case of 'spherulitic-dendritic' crystal containing material, severe brittle fracture of plate like crystals were noted, when both were scratched at 50 N load.

Deformation and Fracture Behavior of Steel Projectiles Impact AD95 Ceramic Targets-Experimental Investigation

NASA Astrophysics Data System (ADS)

Wei, Gang; Zhang, Wei

2013-06-01

The deformation and fracture behavior of steel projectile impacting ceramic target is an interesting investigation topic. The deformation and failure behavior of projectile and target was investigated experimentally in the normal impact by different velocities. Lab-scale ballistic tests of AD95 ceramic targets with 20 mm thickness against two different hardness 38CrSi steel projectiles with 7.62 mm diameter have been conducted at a range of velocities from 100 to 1000 m/s. Experimental results show that, with the impact velocity increasing, for the soft projectiles, the deformation and fracture modes were mushrooming, shear cracking, petalling and fragmentation(with large fragments and less number), respectively; for the hard projectiles there are three deformation and fracture modes: mushrooming, shearing cracking and fragmentation(with small fragments and large number). All projectiles were rebound after impact. But, with the velocity change, the target failure modes have changed. At low velocity, only radial cracks were found; then circumferential cracks appeared with the increasing velocity; the ceramic cone occurred when the velocity reached 400 m/s above, and manifested in two forms: front surface intact at lower velocity and perforated at higher velocity. The higher velocity, the fragment size is smaller and more uniform distribution. The difference of ceramic target damage is not obvious after impacted by two kinds of projectiles with different hardness at the same velocity. National Natural Science Foundation of China (No.: 11072072).

Minerals and design of new waste forms for conditioning nuclear waste

NASA Astrophysics Data System (ADS)

Montel, Jean-Marc

2011-02-01

Safe storage of radioactive waste is a major challenge for the nuclear industry. Mineralogy is a good basis for designing ceramics, which could eventually replace nuclear glasses. This requires a new storage concept: separation-conditioning. Basic rules of crystal chemistry allow one to select the most suitable structures and natural occurrences allow assessing the long-term performance of ceramics in a geological environment. Three criteria are of special interest: compatibility with geological environment, resistance to natural fluids, and effects of self-irradiation. If mineralogical information is efficient for predicting the behaviour of common, well-known minerals, such as zircon, monazite or apatite, more research is needed to rationalize the long-term behaviour of uncommon waste form analogs.

Ductile Binder Phase For Use With Almgb14 And Other Hard Ceramic Materials

DOEpatents

Cook, Bruce A.; Russell, Alan; Harringa, Joel

2005-07-26

This invention relates to a ductile binder phase for use with AlMgB14 and other hard materials. The ductile binder phase, a cobalt-manganese alloy, is used in appropriate quantities to tailor good hardness and reasonable fracture toughness for hard materials so they can be used suitably in industrial machining and grinding applications.

Electroerosion micro- and nanopowders for the production of hard alloys

NASA Astrophysics Data System (ADS)

Latypov, R. A.; Ageeva, E. V.; Kruglyakov, O. V.; Latypova, G. R.

2016-06-01

The shape and the surface morphology of the powder particles fabricated by the electroerosion dispersion of tungsten-containing wastes in illuminating oil are studied. The hard alloy fabricated from these powder particles is analyzed by electron-probe microanalysis. The powder synthesized by the electroerosion dispersion of the wastes of sintered hard alloys is found to consist of particles of a spherical or elliptical shape, an irregular shape (conglomerates), and a fragment shape. It is shown that W, Ti, and Co are the main elements in the hard alloy fabricated from the powder synthesized by electroerosion dispersion in illuminating oil.

Effects of Helium Ion Irradiation on Properties of Crystalline and Amorphous Multiphase Ceramic Coatings

NASA Astrophysics Data System (ADS)

Chen, Yong; Hu, Liangbin; Qiu, Changjun; He, Bin; Wang, Zhongchang

2017-08-01

The Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings were prepared on a martensitic steel by laser in situ reaction technique and impose irradiation with 200 keV He ions at different doses. The helium ion irradiation goes 1.55 μm deep from the surface of coating, and the displacement per atom (dpa) for the Al2O3-TiO2 coating is 20.0. When the irradiation fluency is 5 × 1017 ions/cm2, defects are identified in crystalline areas and there form interfacial areas in the coating. These crystal defects tend to migrate and converge at the interfaces. Moreover, helium ion irradiation is found to exert no effect on surface chemical composition and phase constitution of the coatings, while surface mechanical properties for the coatings after irradiation differ from those before irradiation. Further nano-indentation experiments reveal that surface nano-hardness of the Al2O3-TiO2 multiphase coatings decreases as the helium ions irradiation flux increases. Such Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings exhibit the strongest resistance against helium ion irradiation which shall be applied as candidate structural materials for accelerator-driven sub-critical system to handle the nuclear waste under extreme conditions.

Bioactive and inert dental glass-ceramics.

PubMed

Montazerian, Maziar; Zanotto, Edgar Dutra

2017-02-01

The global market for dental materials is predicted to exceed 10 billion dollars by 2020. The main drivers for this growth are easing the workflow of dentists and increasing the comfort of patients. Therefore, remarkable research projects have been conducted and are currently underway to develop improved or new dental materials with enhanced properties or that can be processed using advanced technologies, such as CAD/CAM or 3D printing. Among these materials, zirconia, glass or polymer-infiltrated ceramics, and glass-ceramics (GCs) are of great importance. Dental glass-ceramics are highly attractive because they are easy to process and have outstanding esthetics, translucency, low thermal conductivity, high strength, chemical durability, biocompatibility, wear resistance, and hardness similar to that of natural teeth, and, in certain cases, these materials are bioactive. In this review article, we divide dental GCs into the following two groups: restorative and bioactive. Most restorative dental glass-ceramics (RDGCs) are inert and biocompatible and are used in the restoration and reconstruction of teeth. Bioactive dental glass-ceramics (BDGCs) display bone-bonding ability and stimulate positive biological reactions at the material/tissue interface. BDGCs are suggested for dentin hypersensitivity treatment, implant coating, bone regeneration and periodontal therapy. Throughout this paper, we elaborate on the history, processing, properties and applications of RDGCs and BDGCs. We also report on selected papers that address promising types of dental glass-ceramics. Finally, we include trends and guidance on relevant open issues and research possibilities. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 619-639, 2017. © 2016 Wiley Periodicals, Inc.

Modified PZT ceramics as a material that can be used in micromechatronics

NASA Astrophysics Data System (ADS)

Zachariasz, Radosław; Bochenek, Dariusz

2015-11-01

Results on investigations of the PZT type ceramics with the following chemical composition: Pb0.94Sr0.06(Zr0.50 Ti0.50)0.99 Cr0.01O3 (PSZTC) which belongs to a group of multicomponent ceramic materials obtained on basis of the PZT type solid solution, are presented in this work. Ceramics PSZTC was obtained by a free sintering method under the following conditions: Tsint = 1250 °C and tsint = 2 h. Ceramic compacts of specimens for the sintering process were made from the ceramic mass consisting of a mixture of the synthesized PSZTC powder and 3% polyvinyl alcohol while wet. The PSZTC ceramic specimens were subjected to poling by two methods: low temperature and high temperature. On the basis of the examinations made it has been found that the ceramics obtained belongs to ferroelectric-hard materials and that is why it may be used to build resonators, filters and ultrasonic transducers. Contribution to the Topical Issue "Materials for Dielectric Applications" edited by Maciej Jaroszewski and Sabu Thomas.

High hardness in the biocompatible intermetallic compound β-Ti3Au

PubMed Central

Svanidze, Eteri; Besara, Tiglet; Ozaydin, M. Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K.; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M.; Morosan, E.

2016-01-01

The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti–Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials. PMID:27453942

Controlling the leakage of liquid bismuth cathode elements in ceramic crucibles used for the electrowinning process in pyroprocessing

NASA Astrophysics Data System (ADS)

Kim, Dae-Young; Hwang, Il-Soon; Lee, Jong-Hyeon

2016-09-01

Pyroprocessing has shown promise as an alternative to wet processing for the recycling of transuranics with a high proliferation resistance. However, a critical issue for pyroprocessing is the ceramic crucibles used in the electrowinning process. These ceramic crucibles are frequently damaged by thermal stress, which results in significant volumes of crucible waste that must be properly disposed. Transuranic waste (TRU) elements intrude throughout the pores of a damaged crucible. The volume of generated radioactive waste is a concern when dealing with nuclear power plants and decontamination issues. In this study, laser treatment and sintering were performed on the crucibles to minimize the TRU elements trapped within. Secondary ion mass spectroscopy was used to measure the intrusion depth of Li in the surface-treated ceramics.

Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration

PubMed Central

Ebrahimi, Mehrdad; Busse, Nadine; Kerker, Steffen; Schmitz, Oliver; Hilpert, Markus; Czermak, Peter

2015-01-01

Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD) and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively. PMID:26729180

Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration.

PubMed

Ebrahimi, Mehrdad; Busse, Nadine; Kerker, Steffen; Schmitz, Oliver; Hilpert, Markus; Czermak, Peter

2015-12-31

Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD) and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively.

A comparative study of progressive wear of four dental monolithic, veneered glass-ceramics.

PubMed

Zhang, Zhenzhen; Yi, Yuanping; Wang, Xuesong; Guo, Jiawen; Li, Ding; He, Lin; Zhang, Shaofeng

2017-10-01

This study evaluated the wear performance and wear mechanisms of four dental glass-ceramics, based on the microstructure and mechanical properties in the progressive wear process. Bar (N = 40, n = 10) and disk (N = 32, n = 8) specimens were prepared from (A) lithium disilicate glass-ceramic (LD), (B) leucite reinforced glass-ceramic (LEU), (C) feldspathic glass-ceramic (FEL), and (D) fluorapatite glass-ceramic (FLU). The bar specimens were tested for three-point flexural strength, hardness, fracture toughness and elastic modulus. The disk specimens paired with steatite antagonists were tested in a pin-on-disk tribometer with 10N up to 1000,000 wear cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 200,000 wear cycles. Wear loss of steatite antagonists was calculated by measuring the weight and density using sensitive balance and Archimedes' method. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). The crystalline phase compositions were determined using X-ray diffraction (XRD). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pair-wise comparison of means was performed by Tukey's post-hoc test. LD showed the highest fracture toughness, flexural strength, elastic modulus and crystallinity, followed by LEU and FEL, and FLU showed the lowest. However, the hardness of LD was lower than all the other three types of ceramics. For steatite antagonists, LD produced the least wear loss of antagonist, followed by LEU and FEL, and FLU had the most wear loss. For glass-ceramic materials, LD exhibited similar wear loss as LEU, but more than FLU and FEL did. Moreover, fracture occurred on the wear surface of FLU. In the progressive wear process, veneering porcelains showed better wear resistance but fluorapatite veneering porcelains appeared fracture surface. Monolithic lithium disilicate glass-ceramics with higher mechanical properties showed more wear loss, however

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.

Lead-Free KNbO3:xZnO Composite Ceramics.

PubMed

Lv, Xiang; Li, Zhuoyun; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo

2016-11-09

It is a tough issue to develop dense and water resistant KNbO 3 ceramics due to high evaporation and hygroscopicity of K 2 O. Here, KNbO 3 :xZnO composite ceramics were used to successfully solve this problem, where ZnO particles were randomly distributed into a KNbO 3 matrix. The addition of ZnO hardly affects the phase structure of KNbO 3 , and moreover, the enhancement of electrical properties, thermal stability, and aging characteristics was observed in KNbO 3 :xZnO composite ceramics. The composites possessed the maximum d 33 of 120 ± 5 pC/N, which is superior to that of pure KNbO 3 (d 33 = 80 pC/N). More importantly, a strong water resistance and an aging-free characteristic were observed in KNbO 3 :0.4ZnO. This is the first time for KNbO 3 ceramics to simultaneously improve electrical properties and resolve the water-absorbing properties. We believe that these composite ceramics are promising for practical applications.

Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite.

PubMed

Zhang, Zhikun; Zhang, Lei; Li, Aimin

2015-04-01

Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment. In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2h) showed the properties of density of 1.92 ± 0.05 g/cm(3), weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was reduced compared to conventional vitrification and sintering method. Chemical resistance and heavy metals leaching results of glass ceramic composites further confirmed the possibility of its engineering applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geopolymers for Structural Ceramic Applications

DTIC Science & Technology

2006-08-31

Applications of geopolymers have included ceramic matrix composites ,ŕ, 3 waste encapsulation 9-11and alternative cements.7,12,14 As adhesives... compositions of the geopolymer adhesive interfaces were studied with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Durable...after thermal shock testing. In response, chopped-fiber reinforced geopolymer composites were processed as possible candidate mold materials for casting

Custom ceramic microchannel-cooled array for high-power fiber-coupled application

NASA Astrophysics Data System (ADS)

Junghans, Jeremy; Feeler, Ryan; Stephens, Ed

2018-03-01

A low-SWaP (Size, Weight and Power) diode array has been developed for a high-power fiber-coupled application. High efficiency ( 65%) diodes enable high optical powers while minimizing thermal losses. A large amount of waste heat is still generated and must be extracted. Custom ceramic microchannel-coolers (MCCs) are used to dissipate the waste heat. The custom ceramic MCC was designed to accommodate long cavity length diodes and micro-lenses. The coolers provide similar thermal performance as copper MCCs however they are not susceptible to erosion and can be cooled with standard filtered water. The custom ceramic micro-channel cooled array was designed to be a form/fit replacement for an existing copperbased solution. Each array consisted of three-vertically stacked MCCs with 4 mm CL, 976 nm diodes and beamshaping micro-optics. The erosion and corrosion resistance of ceramic array is intended to mitigate the risk of copperbased MCC corrosion failures. Elimination of the water delivery requirements (pH, resistivity and dissolved oxygen control) further reduces the system SWaP while maintaining reliability. The arrays were fabricated and fully characterized. This work discusses the advantages of the ceramic MCC technology and describes the design parameters that were tailored for the fiber-coupled application. Additional configuration options (form/fit, micro-lensing, alternate coolants, etc.) and on-going design improvements are also discussed.

Ceramic Integration Technologies for Advanced Energy Systems: Critical Needs, Technical Challenges, and Opportunities

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay

2010-01-01

Advanced ceramic integration technologies dramatically impact the energy landscape due to wide scale application of ceramics in all aspects of alternative energy production, storage, distribution, conservation, and efficiency. Examples include fuel cells, thermoelectrics, photovoltaics, gas turbine propulsion systems, distribution and transmission systems based on superconductors, nuclear power generation and waste disposal. Ceramic integration technologies play a key role in fabrication and manufacturing of large and complex shaped parts with multifunctional properties. However, the development of robust and reliable integrated systems with optimum performance requires the understanding of many thermochemical and thermomechanical factors, particularly for high temperature applications. In this presentation, various needs, challenges, and opportunities in design, fabrication, and testing of integrated similar (ceramic ceramic) and dissimilar (ceramic metal) material www.nasa.gov 45 ceramic-ceramic-systems have been discussed. Experimental results for bonding and integration of SiC based Micro-Electro-Mechanical-Systems (MEMS) LDI fuel injector and advanced ceramics and composites for gas turbine applications are presented.

Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

NASA Astrophysics Data System (ADS)

Wananuruksawong, R.; Jinawath, S.; Padipatvuthikul, P.; Wasanapiarnpong, T.

2011-10-01

Silicon nitride (Si3N4) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si3N4 ceramic as a dental core material. The white Si3N4 was prepared by pressureless sintering at relative low sintering temperature of 1650 °C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si3N4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si3N4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (<150 micrometer, Pyrex) with 5 wt% of zirconia powder (3 wt% Y2O3 - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si3N4 specimens, the firing was performed in electric tube furnace between 1000-1200°C. The veneered specimens fired at 1100°C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98×10-6 °C-1, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

Static and fatigue mechanical behavior of three dental CAD/CAM ceramics.

PubMed

Homaei, Ehsan; Farhangdoost, Khalil; Tsoi, James Kit Hon; Matinlinna, Jukka Pekka; Pow, Edmond Ho Nang

2016-06-01

The aim of this study was to measure the mechanical properties and fatigue behavior of three contemporary used dental ceramics, zirconia Cercon(®) (ZC), lithium disilicate e.max(®) CAD (LD), and polymer-infiltrated ceramic Enamic(®) (PIC). Flexural strength of each CAD/CAM ceramic was measured by three point bending (n=15) followed by Weibull analysis. Elastic modulus was calculated from the load-displacement curve. For cyclic fatigue loading, sinusoidal loading with a frequency of 8Hz with minimum load 3N were applied to these ceramics (n=24) using three point bending from 10(3) to 10(6) cycles. Fatigue limits of these ceramics were predicted with S-N fatigue diagram. Fracture toughness and Vickers hardness of the ceramics were measured respectively by single edge V-notch beam (SEVNB) and microindentation (Hv 0.2) methods. Chemical compositions of the materials׳ surfaces were analyzed by EDS, and microstructural analysis was conducted on the fracture surfaces by SEM. One-way ANOVA was performed and the level of significance was set at 0.05 to analyze the numerical results. The mean flexural strength of ZC, LD, and PIC was respectively 886.9, 356.7, and 135.8MPa. However, the highest Weibull modulus belonged to PIC with 19.7 and the lowest was found in LD with 7.0. The fatigue limit of maximum load for one million cycles of ZC, LD, and PIC was estimated to be 500.1, 168.4, and 73.8GPa. The mean fracture toughness of ZC, LD, and PIC was found to be respectively 6.6, 2.8, and 1.4MPam(1/2), while the mean Vickers hardness was 1641.7, 676.7, and 261.7Hv. Fracture surfaces followed fatigue loading appeared to be smoother than that after monotonic loading. Mechanical properties of ZC were substantially superior to the two other tested ceramics, but the scattering of data was the least in PIC. The fatigue limit was found to be approximately half of the mean flexural strength for all tested ceramics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cost-effective method for determining the grindability of ceramics. Final report

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

Guo, C.; Chand, R.H.

1997-02-01

The objective of this program was to develop a cost-effective method to determine the grindability of ceramics leading to cost-effective methods for machining such ceramics. In this first phase of activity, Chand Kare Technical Ceramics directed its efforts towards development of a definition for ceramic grindability, design of grindability-test experiments, and development of a ceramics-grindability test system (CGTS). The grindability study also included the establishment of the correlation between the grindability and conventional grinding practices. The above goals were achieved. A definition based on material removal rate under controlled force grinding was developed. Three prototypes CGTSs were developed and tested;more » suitable design was identified. Based on this, a fully automatic CGTS was developed and is ready for delivery to Oak Ridge National Laboratory. Comprehensive grindability tests for various commercially available engineering ceramics were conducted. Experimental results indicated that ceramics have significantly different grindabilities even though their mechanical properties were not significantly different. This implies that grindability of ceramics can be greatly improved. Further study is needed to establish correlations between microstructure and grindability. Therefore, grindability should be evaluated during the development of new ceramics or improvement of existing ones. In this report, the development of the ceramic-grindability definition, the development of CGTS, extensive grindability results, and the preliminary correlation between grindability and mechanical properties (such as flexural strength, hardness, elastic modulus, and fracture toughness) were summarized.« less

Oxidized zirconium on ceramic; Catastrophic coupling.

PubMed

Ozden, V E; Saglam, N; Dikmen, G; Tozun, I R

2017-02-01

Oxidized zirconium (Oxinium™; Smith & Nephew, Memphis, TN, USA) articulated with polyethylene in total hip arthroplasty (THA) appeared to have the potential to reduce wear dramatically. The thermally oxidized metal zirconium surface is transformed into ceramic-like hard surface that is resistant to abrasion. The exposure of soft zirconium metal under hard coverage surface after the damage of oxidized zirconium femoral head has been described. It occurred following joint dislocation or in situ succeeding disengagement of polyethylene liner. We reported three cases of misuse of Oxinium™ (Smith & Nephew, Memphis, TN, USA) heads. These three cases resulted in catastrophic in situ wear and inevitable failure although there was no advice, indication or recommendation for this use from the manufacturer. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness.

PubMed

Reges, Rogério Vieira; Costa, Ana Rosa; Correr, Américo Bortolazzo; Piva, Evandro; Puppin-Rontani, Regina Maria; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

2009-01-01

The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm(2), respectively. The Koop hardness was measured using a microhardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey's test (alpha=0.05). The QTH LCU provided significantly higher (p<0.05) KHN values than the LED LCU. When the post-cure times were compared for the same shade, QTH and LED at 24 h provided significantly higher (p<0.05) KHN values than at 15 min. It may be concluded that the Knoop hardness was generally dependent on the LCU and post-cure time. The opaque shade of the resin cement showed lower Knoop hardness than the other shades for both LCUs and post-cure times.

Ternary ceramic alloys of ZR-CE-HF oxides

DOEpatents

Becher, Paul F.; Funkenbusch, Eric F.

1990-01-01

A ternary ceramic alloy which produces toughening of zirconia and zirconia composites through the stress transformation from tetragonal phase to monoclinic phase. This alloy, having the general formula Ce.sub.x Hf.sub.y Zn.sub.1-x-y O.sub.2, is produced through the addition of appropriate amounts of ceria and hafnia to the zirconia. Typically, improved toughness is achieved with about 5 to about 15 mol % ceria and up to about 40 mol % hafnia. The preparation of alloys of these compositions are given together with data as to the densities, tetragonal phase content, hardness and fracture toughness. The alloys are useful in preparing zirconia bodies as well as reinforcing ceramic composites.

XRD investigation of the Effect of MgO Additives on ZTA-TiO2 Ceramic Composites

NASA Astrophysics Data System (ADS)

Azhar, Ahmad Zahirani Ahmad; Manshor, Hanisah; Ali, Afifah Mohd

2018-01-01

Alumina (Al2O3) based ceramics possess good mechanical properties and suitable for the application of cutting inserts. However, this monolithic ceramics suffer from lack of toughness. Hence, there are some modification were made such as the addition of yttria stabilized zirconia (YSZ) to the Al2O3 helps in increasing the toughness of the Al2O3 ceramics. Some additives such as MgO and TiO2 were used to further improve the mechanical properties of ZTA. In this study, high purity raw materials which consist of ZTA-TiO2 were mixed with different amount of MgO (0.0 - 1.0 wt %). The mixture of materials was going through wet mixing, compaction and pressureless sintering at 1600°C for one hour. The samples were characterized for phase analysis, microstructure, shrinkage rate, bulk density, Vickers hardness and fracture toughness. Based on the XRD analysis results, the secondary phase (MgAl2O4) was detected in the sample with 0.5 wt% of MgO onwards which leads to grains refinement, thus improve the density and hardness of ZTA-TiO2-MgO ceramics composites.

High-level waste program progress report, April 1, 1980-June 30, 1980

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

None

1980-08-01

The highlights of this report are on: waste management analysis for nuclear fuel cycles; fixation of waste in concrete; study of ceramic and cermet waste forms; alternative high-level waste forms development; and high-level waste container development.

Production of coloured glass-ceramics from incinerator ash using thermal plasma technology.

PubMed

Cheng, T W; Huang, M Z; Tzeng, C C; Cheng, K B; Ueng, T H

2007-08-01

Incineration is a major treatment process for municipal solid waste in Taiwan. It is estimated that over 1.5 Mt of incinerator ash are produced annually. This study proposes using thermal plasma technology to treat incinerator ash. Sintered glass-ceramics were produced using quenched vitrified slag with colouring agents added. The experimental results showed that the major crystalline phases developed in the sintered glass-ceramics were gehlenite and wollastonite, but many other secondary phases also appeared depending on the colouring agents added. The physical/mechanical properties, chemical resistance and toxicity characteristic leaching procedure of the coloured glass-ceramics were satisfactory. The glass-ceramic products obtained from incinerator ash treated with thermal plasma technology have great potential for building applications.

Evidence of technetium and iodine release from a sodalite-bearing ceramic waste form

DOE PAGES

Neeway, James J.; Qafoku, Nikolla P.; Williams, Benjamin D.; ...

2015-12-31

We proposed sodalites as a possible host of certain radioactive species, specifically 99Tc and 129I, which may be encapsulated into the cage structure of the mineral. To demonstrate the ability of this framework silicate mineral to encapsulate and immobilize 99Tc and 129I, single-pass flow-through (SPFT) tests were conducted on a sodalite-bearing multi-phase ceramic waste form produced through a steam reforming process. We produced two samples made using a steam reformer samples using nonradioactive I and Re (as a surrogate for Tc), while a third sample was produced using actual radioactive tank waste containing Tc and added Re. One of themore » non-radioactive samples was produced with an engineering-scale steam reformer while the other non-radioactive sample and the radioactive sample were produced using a bench-scale steam reformer. For all three steam reformer products, the similar steady-state dilute-solution release rates for Re, I, and Tc at pH (25 C) 9 and 40 C were measured. However, it was found that the Re, I, and Tc releases were equal or up to 4.5x higher compared to the release rates of the network-forming elements, Na, Al, and Si. Moreover, the similar releases of Re and Tc in the SPFT test, and the similar time-dependent shapes of the release curves for samples containing I, suggest that Re, Tc, and I partition to the sodalite minerals during the steam reforming process.« less

Recycling of residual IGCC slags and their benefits as degreasers in ceramics.

PubMed

Iglesias Martín, I; Acosta Echeverría, A; García-Romero, E

2013-11-15

This work studies the evolution of IGCC slag grains within a ceramic matrix fired at different temperatures to investigate the effect of using IGCC slag as a degreaser. Pressed ceramic specimens from two clay mixtures are used in this study. The M1 mixture is composed of standard clays, whereas the M2 mixture is composed of the same clay mixture as M1 mixture but contains 15% by weight IGCC slag. The amount of IGCC slag added coincides with the amount of slag typically used as a degreaser in the ceramic industry. Specimens are fired at 950 °C, 1000 °C, 1050 °C, 1100 °C and 1150 °C. The mineralogical composition and the IGCC slag grain shape within the ceramic matrix are determined by X-ray diffraction, polarized light microscopy and scanning electron microscopy. The results reveal that the surface of the slag grains is welded to the ceramic matrix while the quartz grains are separated, which causes increased water absorption and reduces the mechanical strength. IGCC slag, however, reduces water absorption. This behaviour is due to the softening temperature of the slag. This property is quite important from an industrial viewpoint because IGCC slag can serve as an alternative to traditional degreasing agents in the ceramic building industry. Additionally, using IGCC slag allows for the transformation of waste into a secondary raw material, thereby avoiding disposal at landfills; moreover, these industrial wastes are made inert and improve the properties of ceramics. Copyright © 2013 Elsevier Ltd. All rights reserved.

Use of municipal solid waste incineration bottom ashes in alkali-activated materials, ceramics and granular applications: A review.

PubMed

Silva, R V; de Brito, J; Lynn, C J; Dhir, R K

2017-10-01

This paper presents a literature review on the incorporation of municipal solid waste incinerated bottom ash as raw material in several markets, other than those where it is conventionally used, such as geotechnical applications and road pavement construction. The main findings of an ample selection of experimental investigations on the use of the bottom ash as precursor of alkali-activated materials, as an adsorbent material for the removal of hazardous elements from wastewater and landfill gases, as soil replacement in agricultural activities, as partial or complete substitute of raw materials for the manufacture of ceramic-based products, as landfill cover and as biogas production enhancer, were gathered, collated and analysed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ceramic waste form production and development at ANL-West.

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

Battisti, T. J.; Goff, K. M.; Bateman, K. J.

2002-08-21

Argonne National Laboratory has developed a method to stabilize spent electrolyte salt discarded from electrorefiners (ER) used to treat spent nuclear fuel. The salt is stabilized in a ceramic using a pressureless consolidation technique. The starting material is zeolite 4A which is used as the host for the fission product and actinide rich salt. Glass frit is added to the salt loaded zeolite before processing to act as a binder. The zeolite 4A is converted to sodalite during processing via pressureless consolidation. This process differs from one used in the past that employed a hot isostatic press. Ceramic is createdmore » at 925 C and atmospheric pressure instead of the high pressures used in hot isostatic pressing. Process flow sheets, off-gas test results, processing equipment, and leech test results are presented.« less

Identification of Technological Parameters of Ni-Alloys When Machining by Monolithic Ceramic Milling Tool

NASA Astrophysics Data System (ADS)

Czán, Andrej; Kubala, Ondrej; Danis, Igor; Czánová, Tatiana; Holubják, Jozef; Mikloš, Matej

2017-12-01

The ever-increasing production and the usage of hard-to-machine progressive materials are the main cause of continual finding of new ways and methods of machining. One of these ways is the ceramic milling tool, which combines the pros of conventional ceramic cutting materials and pros of conventional coating steel-based insert. These properties allow to improve cutting conditions and so increase the productivity with preserved quality known from conventional tools usage. In this paper, there is made the identification of properties and possibilities of this tool when machining of hard-to-machine materials such as nickel alloys using in airplanes engines. This article is focused on the analysis and evaluation ordinary technological parameters and surface quality, mainly roughness of surface and quality of machined surface and tool wearing.

Method for producing chemically bonded phosphate ceramics and for stabilizing contaminants encapsulated therein utilizing reducing agents

DOEpatents

Singh, Dileep; Wagh, Arun S.; Jeong, Seung-Young

2000-01-01

Known phosphate ceramic formulations are improved and the ability to produce iron-based phosphate ceramic systems is enabled by the addition of an oxidizing or reducing step during the acid-base reactions that form the phosphate ceramic products. The additives allow control of the rate of the acid-base reactions and concomitant heat generation. In an alternate embodiment, waste containing metal anions are stabilized in phosphate ceramic products by the addition of a reducing agent to the phosphate ceramic mixture. The reduced metal ions are more stable and/or reactive with the phosphate ions, resulting in the formation of insoluble metal species within the phosphate ceramic matrix, such that the resulting chemically bonded phosphate ceramic product has greater leach resistance.

Method of making metal matrix composites reinforced with ceramic particulates

DOEpatents

Cornie, James A.; Kattamis, Theodoulos; Chambers, Brent V.; Bond, Bruce E.; Varela, Raul H.

1989-01-01

Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys.

Method of making metal matrix composites reinforced with ceramic particulates

DOEpatents

Cornie, J.A.; Kattamis, T.; Chambers, B.V.; Bond, B.E.; Varela, R.H.

1989-08-01

Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys. 2 figs.

Investigation on Surface Insulation Strength of Machinable Ceramic Material under Pulsed Voltage in Vacuum

NASA Astrophysics Data System (ADS)

Zhang, Guan-Jun; Zhao, Wen-Bin; Ma, Xin-Pei; Li, Guang-Xin; Ma, Kui; Zheng, Nan; Yan, Zhang

Ceramic material has been widely used as insulator in vacuum. Their high hardness and brittle property brings some difficulty in the application. A new kind of machinable ceramic was invented recently. The ceramic can be machined easily and accurately after being sintered, which provides the possibility of making the insulator with fine and complicated configuration. The paper studies its surface insulation performance and flashover phenomena under pulsed excitation in vacuum. The ceramic samples with different crystallization parameters are tested under the vacuum level of 10-4 Pa. The machinable ceramic behaves better surface insulation performance than comparative the Al2O3 and glass sample. The effect of crystallization level on the trap density and flashover current is also presented. After flashover shots many times, the surface microscopic patterns of different samples are observed to investigate the damage status, which can be explained by the thermal damage mechanism.

Ternary ceramic alloys of Zr-Ce-Hf oxides

DOEpatents

Becher, P.F.; Funkenbusch, E.F.

1990-11-20

A ternary ceramic alloy is described which produces toughening of zirconia and zirconia composites through the stress transformation from tetragonal phase to monoclinic phase. This alloy, having the general formula Ce[sub x]Hf[sub y]Zr[sub 1[minus]x[minus]y]O[sub 2], is produced through the addition of appropriate amounts of ceria and hafnia to the zirconia. Typically, improved toughness is achieved with about 5 to about 15 mol % ceria and up to about 40 mol % hafnia. The preparation of alloys of these compositions are given together with data as to the densities, tetragonal phase content, hardness and fracture toughness. The alloys are useful in preparing zirconia bodies as well as reinforcing ceramic composites. 1 fig.

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness.

PubMed

Ayyıldız, Simel; Soylu, Elif Hilal; Ide, Semra; Kılıç, Selim; Sipahi, Cumhur; Pişkin, Bulent; Gökçe, Hasan Suat

2013-11-01

The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness

PubMed Central

Soylu, Elif Hilal; İde, Semra; Kılıç, Selim; Sipahi, Cumhur; Pişkin, Bulent; Gökçe, Hasan Suat

2013-01-01

PURPOSE The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). CONCLUSION After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic

Aluminium surface treatment with ceramic phases using diode laser

NASA Astrophysics Data System (ADS)

Labisz, K.; Tański, T.; Brytan, Z.; Pakieła, W.; Wiśniowski, M.

2016-07-01

Ceramic particles powder feeding into surface layer of engineering metal alloy is a well-known and widely used technique. New approach into the topic is to obtain finely distributed nano-sized particles involved in the aluminium matrix using the traditional laser technology. In this paper are presented results of microstructure investigation of cast aluminium-silicon-copper alloys surface layer after heat treatment and alloying with ceramic carbides of WC and ZrO2 using high-power diode laser. The surface layer was specially prepared for the reason of reducing the reflectivity, which is the main problem in the up-to-date metal matrix composites production. With scanning electron microscopy, it was possible to determine the deformation process and distribution of WC and ZrO2 ceramic powder phase. Structure of the surface after laser treatment changes, revealing three zones—remelting zone, heat-affected zone and transition zone placed over the Al substrate. The structural changes of ceramic powder, its distribution and morphology as well as microstructure of the matrix material influence on functional properties, especially wear resistance and hardness of the achieved layer, were investigated.

Microhardness evaluations of CAD/CAM ceramics irradiated with CO2 or Nd:YAP laser

PubMed Central

Rocca, Jean Paul; Fornaini, Carlo; Medioni, Etienne; Brulat-Bouchard, Nathalie

2017-01-01

Background and aims The aim of this study was to measure the microhardness values of irradiated computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics surfaces before and after thermal treatment. Materials and Methods Sixty CAD/CAM ceramic discs were prepared and grouped by material, i.e. lithium disilicate ceramic (Emax CAD) and zirconia ceramic (Emax ZirCAD). Laser irradiation at the material surface was performed with a carbon dioxide laser at 5 Watt (W) or 10 W power in continuous mode (CW mode), or with a neodymium:yttrium aluminum perovskite (Nd:YAP) laser at 10 W on graphite and non-graphite surfaces. Vickers hardness was tested at 0.3 kgf for lithium disilicate and 1 kgf for zirconia. Results Emax CAD irradiated with CO2 at 5 W increased microhardness by 6.32 GPa whereas Emax ZirCAD irradiated with Nd:YAP decreased microhardness by 17.46 GPa. Conclusion CO2 laser effectively increases the microhardness of lithium disilicate ceramics (Emax CAD). PMID:28740324

MANAGEMENT AND TREATMENT OF WATER FROM HARD-ROCK MINES {ENGINEERING ISSUE}

EPA Science Inventory

This Engineering Issue document on treatment of mining waters is a practical guide to understanding and selecting technologies for the environmental management of waste materials and effluents at hard-rock mines. For the purposes of this discussion, hard-rock mining primarily ref...

Surface roughness analysis after laser assisted machining of hard to cut materials

NASA Astrophysics Data System (ADS)

Przestacki, D.; Jankowiak, M.

2014-03-01

Metal matrix composites and Si3N4 ceramics are very attractive materials for various industry applications due to extremely high hardness and abrasive wear resistance. However because of these features they are problematic for the conventional turning process. The machining on a classic lathe still requires special polycrystalline diamond (PCD) or cubic boron nitride (CBN) cutting inserts which are very expensive. In the paper an experimental surface roughness analysis of laser assisted machining (LAM) for two tapes of hard-to-cut materials was presented. In LAM, the surface of work piece is heated directly by a laser beam in order to facilitate, the decohesion of material. Surface analysis concentrates on the influence of laser assisted machining on the surface quality of the silicon nitride ceramic Si3N4 and metal matrix composite (MMC). The effect of the laser assisted machining was compared to the conventional machining. The machining parameters influence on surface roughness parameters was also investigated. The 3D surface topographies were measured using optical surface profiler. The analysis of power spectrum density (PSD) roughness profile were analyzed.

Optical method and apparatus for detection of defects and microstructural changes in ceramics and ceramic coatings

DOEpatents

Ellingson, William A.; Todd, Judith A.; Sun, Jiangang

2001-01-01

Apparatus detects defects and microstructural changes in hard translucent materials such as ceramic bulk compositions and ceramic coatings such as after use under load conditions. The beam from a tunable laser is directed onto the sample under study and light reflected by the sample is directed to two detectors, with light scattered with a small scatter angle directed to a first detector and light scattered with a larger scatter angle directed to a second detector for monitoring the scattering surface. The sum and ratio of the two detector outputs respectively provide a gray-scale, or "sum" image, and an indication of the lateral spread of the subsurface scatter, or "ratio" image. This two detector system allows for very high speed crack detection for on-line, real-time inspection of damage in ceramic components. Statistical image processing using a digital image processing approach allows for the quantative discrimination of the presence and distribution of small flaws in a sample while improving detection reliability. The tunable laser allows for the penetration of the sample to detect defects from the sample's surface to the laser's maximum depth of penetration. A layered optical fiber directs the incoming laser beam to the sample and transmits each scattered signal to a respective one of the two detectors.

Recent Observations on the Performance of Hybrid Ceramic Tribo-Contacts

NASA Astrophysics Data System (ADS)

Buttery, M.; Cropper, M.; Wardzinski, B.; Lewis, S.; McLaren, S.; Kreuser, J.

2015-09-01

Hybrid ceramic ball bearings offer great promise in space applications but have not been rapidly adopted by industry perhaps partly due to the relatively low amount of published data on specific in-vacuum performance. Such bearings, having, typically, silicon nitride balls and 440C or high nitrogen steel (e.g. X30) raceways offer the potential for long life and low torque noise due a combination of chemical inertness, high hardness and the extremely smooth surfaces produced in ceramic balls. Though initial benefits were foreseen for high speed applications, the potential for reduced adhesive forces and wear in conditions of marginal lubrication, and for improvements in lubricant lifetime in long life applications limited by oil tribo-degradation render hybrid ceramic bearings more generally attractive.This paper draws together a number of experimental studies carried out at Pin-on-Disc (POD), Spiral Orbit Tribometer (SOT) and bearing-level recently at ESTL.

Strengthening and Strength Uniformity of Structural Ceramics.

DTIC Science & Technology

1983-05-01

overnight to convert the Y(N03 )3 to Y203 . The composite power was ground with a mortar and pestle , and then axially pressed (4000 psi) into...agent, in materials that exhibit a phenomena known as transformation toughening. 2. Control of Crack Size Fracture origins in virgin ceramics are in some...surfactants, or hard, i.e., partially sintered groups of particles which require attrition to dismember. All dry powders *Adjusted to the propensity of the

Waste minimization/pollution prevention study of high-priority waste streams

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

Ogle, R.B.

1994-03-01

Although waste minimization has been practiced by the Metals and Ceramics (M&C) Division in the past, the effort has not been uniform or formalized. To establish the groundwork for continuous improvement, the Division Director initiated a more formalized waste minimization and pollution prevention program. Formalization of the division`s pollution prevention efforts in fiscal year (FY) 1993 was initiated by a more concerted effort to determine the status of waste generation from division activities. The goal for this effort was to reduce or minimize the wastes identified as having the greatest impact on human health, the environment, and costs. Two broadmore » categories of division wastes were identified as solid/liquid wastes and those relating to energy use (primarily electricity and steam). This report presents information on the nonradioactive solid and liquid wastes generated by division activities. More specifically, the information presented was generated by teams of M&C staff members empowered by the Division Director to study specific waste streams.« less

Application of Recycled Ceramic Aggregates for the Production of Mineral-Asphalt Mixtures.

PubMed

Andrzejuk, Wojciech; Barnat-Hunek, Danuta; Siddique, Rafat; Zegardło, Bartosz; Łagód, Grzegorz

2018-04-24

This paper describes a method of designing and producing innovative mineral⁻asphalt mixtures, which utilize waste aggregate from the recycling of sanitary ceramics. The work presents the basic properties of the ceramic material, the investigation concerning the microstructure of the aggregate obtained from the grinding of waste, and a comparison with the images obtained for the aggregates usually employed in mineral⁻asphalt mixtures. The mixtures were designed for the application in the wearing course. Four series of mixtures were prepared. In the first and second, the ceramic aggregate constituted a partial substitute for dolomite, whereas in the third, we substituted granodiorite, and the fourth series contained only dolomite. The mixtures were examined for the content of soluble binder, the bulk density of samples, the presence of voids, the space filled with binder, and the susceptibility to water and frost corrosion. The obtained results were compared with the standard requirements. The microstructure as well as the contact zone in the considered mineral⁻asphalt mixtures are presented based on research conducted by means of a scanning electron microscope (SEM).

Application of Recycled Ceramic Aggregates for the Production of Mineral-Asphalt Mixtures

PubMed Central

Andrzejuk, Wojciech; Barnat-Hunek, Danuta; Siddique, Rafat; Zegardło, Bartosz; Łagód, Grzegorz

2018-01-01

This paper describes a method of designing and producing innovative mineral–asphalt mixtures, which utilize waste aggregate from the recycling of sanitary ceramics. The work presents the basic properties of the ceramic material, the investigation concerning the microstructure of the aggregate obtained from the grinding of waste, and a comparison with the images obtained for the aggregates usually employed in mineral–asphalt mixtures. The mixtures were designed for the application in the wearing course. Four series of mixtures were prepared. In the first and second, the ceramic aggregate constituted a partial substitute for dolomite, whereas in the third, we substituted granodiorite, and the fourth series contained only dolomite. The mixtures were examined for the content of soluble binder, the bulk density of samples, the presence of voids, the space filled with binder, and the susceptibility to water and frost corrosion. The obtained results were compared with the standard requirements. The microstructure as well as the contact zone in the considered mineral–asphalt mixtures are presented based on research conducted by means of a scanning electron microscope (SEM). PMID:29695115

Study of the Wavelength Dependence in Laser Ablation of Advanced Ceramics and Glass-Ceramic Materials in the Nanosecond Range

PubMed Central

Sola, Daniel; Peña, Jose I.

2013-01-01

In this work, geometrical dimensions and ablation yields as a function of the machining method and reference position were studied when advanced ceramics and glass-ceramic materials were machined with pulsed lasers in the nanosecond range. Two laser systems, emitting at 1064 and 532 nm, were used. It was shown that the features obtained depend on whether the substrate is processed by means of pulse bursts or by grooves. In particular, when the samples were processed by grooves, machined depth, removed volume and ablation yields reached their maximum, placing the sample out of focus. It was shown that these characteristics do not depend on the processing conditions, the wavelength or the optical configuration, and that this is intrinsic behavior of the processing method. Furthermore, the existence of a close relation between material hardness and ablation yields was demonstrated. PMID:28788391

Production of brown and black pigments by using flotation waste from copper slag.

PubMed

Ozel, Emel; Turan, Servet; Coruh, Semra; Ergun, Osman Nuri

2006-04-01

One of the major problems in copper-producing countries is the treatment of the large amount of copper slag or copper flotation waste generated from copper slag which contains significant amounts of heavy metals such as Cu, Zn, Pb and Co. Dumping or disposal of such large quantities of flotation waste from copper slag causes environmental and space problems. In this study, the treatment of flotation waste from copper slag by a thermal method and its use as an iron source in the production of inorganic brown and black pigments that are used in the ceramic industry were investigated. The pigments were produced by calcining different amounts of flotation waste and chromite, Cr2O3, ZnO and CoO mixtures. The pigments obtained were added to transparent ceramic glazes and porcelainized tile bodies. Their colours were defined by L*a*b* measurements with a spectrophotometer. The results showed that flotation waste from copper slag could be used as an iron source to produce brown and black pigments in both ceramic body and glazes.

A novel method for isolation and recovery of ceramic nanoparticles and metal wear debris from serum lubricants at ultra-low wear rates.

PubMed

Lal, S; Hall, R M; Tipper, J L

2016-09-15

Ceramics have been used to deliver significant improvements in the wear properties of orthopaedic bearing materials, which has made it challenging to isolate wear debris from simulator lubricants. Ceramics such as silicon nitride, as well as ceramic-like surface coatings on metal substrates have been explored as potential alternatives to conventional implant materials. Current isolation methods were designed for isolating conventional metal, UHMWPE and ceramic wear debris. In this paper, we describe a methodology for isolation and recovery of ceramic or ceramic-like coating particles and metal wear particles from serum lubricants under ultra-low and low wear performance. Enzymatic digestion was used to digest the serum proteins and sodium polytungstate was used as a novel density gradient medium to isolate particles from proteins and other contaminants by ultracentrifugation. This method demonstrated over 80% recovery of particles and did not alter the size or morphology of ceramic and metal particles during the isolation process. Improvements in resistance to wear and mechanical damage of the articulating surfaces have a large influence on longevity and reliability of joint replacement devices. Modern ceramics have demonstrated ultra-low wear rates for hard-on-hard total hip replacements. Generation of very low concentrations of wear debris in simulator lubricants has made it challenging to isolate the particles for characterisation and further analysis. We have introduced a novel method to isolate ceramic and metal particles from serum-based lubricants using enzymatic digestion and novel sodium polytungstate gradients. This is the first study to demonstrate the recovery of ceramic and metal particles from serum lubricants at lowest detectable in vitro wear rates reported in literature. Copyright © 2016. Published by Elsevier Ltd.

Deformation mechanisms in advanced structural ceramics due to indentation and scratch processes

NASA Astrophysics Data System (ADS)

Ghosh, Dipankar

Plasma pressure compaction technique was used to develop boron carbide (B4C) and zirconium diboride-silicon carbide (ZrB2-SiC) composite. B4C ceramics are extensively used as body armor in military and civilian applications, and ZrB2-SiC composite has been recognized as a potential candidate for high-temperature aerospace applications. In this dissertation, processing parameters, quasistatic and high-strain rate mechanical response, and fundamental deformation mechanisms of these materials have been investigated. In the case of B4C, the rate sensitivity of indentation hardness was determined using a dynamic indentation hardness tester that can deliver loads in 100 micros. By comparing dynamic hardness with the static hardness, it was found that B4C exhibits a lower hardness at high-strain rate, contrary to known behavior in many structural ceramics. However, these results are consistent with the ballistic testing of B4C armors as reported in recent literature. This behavior was further investigated using a series of spectroscopic techniques such as visible and UV micro-Raman, photoluminescence and infrared. These studies not only confirmed that structural transformation occurred during indentation experiments similar to that in ballistic testing of B4C but also suggested a greater degree of structural changes under dynamic loading compared to static loading. Due to the potential application as external heat shields in supersonic vehicles, scratch studies were conducted on the ZrB2-SiC composite. These studies revealed metal-like slip-line patterns which are indeed an unusual in brittle solids at room-temperature. Utilizing classical stress field solutions under combined normal and tangential loads, a rationale was developed for understanding the formation of scratch-induced deformation features. Also, an analytical framework was developed, combining the concept of 'blister field' and the 'secular equation' relating Raman peaks to strain, to measure scratch

Transmitted irradiance through ceramics: effect on the mechanical properties of a luting resin cement.

PubMed

Ilie, Nicoleta

2017-05-01

The study aims to characterise the curing behaviour of a light-curing luting composite (Variolink® Aesthetic LC, Ivoclar Vivadent) polymerised at different exposure times (10 s, 20 s) through different ceramics (IPS Empress CAD and IPS e.max CAD, Ivoclar Vivadent) and ceramic thicknesses (no ceramic, 0.5, 1, 1.5 and 2 mm). Curing units' (Bluephase Style, Ivoclar Vivadent) variation in irradiance delivered up to 10-mm exposure distance as well as the incident and transmitted irradiance and radiant exposure up to 6-mm ceramic thickness were assessed on a laboratory-grade spectrometer. A total of 216 (18 groups, n = 12) thin and flat luting composite specimens of 500-μm thickness were prepared and stored after curing in a saturated vapour atmosphere for 24 h at 37 °C. Micro-mechanical properties (Vickers hardness, HV and indentation modulus, Y HU ) were determined by means of an automatic micro-hardness indenter. Within the study design, the radiant exposure received by the luting composite varied from 2.56 to 24.75 J/cm 2 , showing a high impact on the measured properties. Comparing the effect of the parameters exposure time, ceramic thickness and type, the highest influence on the micro-mechanical parameters was identified for exposure time, while this influence was stronger on HV (p < 0.001, η P 2  = 0.452) than on Y HU (p < 0.001, η P 2  = 0.178). The influence of ceramic type was significant but low (η P 2  = 0.161 on HV and 0.113 on Y HU ), while the influence of ceramic thickness was the lowest (η P 2  = 0.04 and 0.05, respectively). Slightly higher irradiance values were transmitted through Empress CAD up to a ceramic thickness of 3 mm (p < 0.001), while being comparable with e.max for thicker slices. Differences in translucency between ceramics were reflected in the micro-mechanical properties of the luting composite. The radiant exposure reaching the luting composite is determined by the incident irradiance, exposure time

New nanostructured ceramics from baddeleyite with improved mechanical properties for biomedical applications

NASA Astrophysics Data System (ADS)

Tyurin, Alexander I.; Zhigachev, Andrey O.; Umrikhin, Alexey V.; Rodaev, Vyacheslav V.; Korenkov, Viktor V.; Pirozhkova, Tatyana S.

2017-12-01

A method for the preparation of novel nanostructured zirconia ceramics from natural zirconia mineral—baddeleyite—using CaO as the stabilizer is described in the present work. Optimal synthesis conditions, including calcia content, planetary mill treatment regime, sintering time and temperature, corresponding to the highest values of hardness H, Young modulus E, and fracture toughness KC are found. The values of the mechanical properties H = 10.8 GPa, E = 200 GPa, and KC = 13.3 MPa m1/2 are comparable with or exceed the corresponding properties of commercial yttria-stabilized ceramics prepared from chemically precipitated zirconia.

The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contact

NASA Technical Reports Server (NTRS)

Sliney, Harold E.; Dellacorte, Christopher

1993-01-01

The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900 C (in a few cases to 1200 C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal.

Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard.

PubMed

Rodríguez-Robles, Desirée; García-González, Julia; Juan-Valdés, Andrés; Morán-Del Pozo, Julia Mª; Guerra-Romero, Manuel I

2014-08-13

Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW.

Influence of energy density of different light sources on Knoop hardness of a dual-cured resin cement.

PubMed

Piva, Evandro; Correr-Sobrinho, Lourenço; Sinhoreti, Mario Alexandre Coelho; Consani, Simonides; Demarco, Flávio Fernando; Powers, John Michael

2008-01-01

The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm(-2) (I/2x2T), 24 Jcm(-2) (IxT) and 48 Jcm(-2) (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (alpha=5%). Application of 48 J.cm(-2) energy dose through the ceramic using LED (50.5+/-2.8) and HAL (50.9+/-3.7) produced significantly higher KHN means (p<0.05) than the control (44.7+/-3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

Penetration Resistance of Armor Ceramics: Dimensional Analysis and Property Correlations

DTIC Science & Technology

2015-08-01

been reported in experimental studies. Particular ceramics analyzed here are low- and high-purity alumina, aluminum nitride, boron carbide, silicon...analyzed here are low- and high-purity alumina, aluminum nitride, boron carbide, silicon carbide, and titanium diboride. Data for penetration depth...include high hardness, high elastic stiffness, high strengths (static/dynamic compressive, shear, and bending), and low density relative to armor steels

Processing and properties of ceramic matrix-polymer composites for dental applications

NASA Astrophysics Data System (ADS)

Huang, Hsuan Yao

The basic composite structure of natural hard tissue was used to guide the design and processing of dental restorative materials. The design incorporates the methodology of using inorganic minerals as the main structural phase reinforced with a more ductile but tougher organic phase. Ceramic-polymer composites were prepared by slip casting a porous ceramic structure, heating and chemical treating the porous preform, infiltrating with monomer and then curing. The three factors that determined the mechanical properties of alumina-polymer composites were the type of polymer used, the method of silane treatments, and the type of bond between particles in the porous preforms. Without the use of silane coupling agents, the composites were measured to have a lower strength. The composite with a more "flexible" porous alumina network had a greater ability to plastically dissipate the energy of propagating cracks. However, the aggressive nature of the alumina particles on opposing enamel requires that these alumina-polymer composites have a wear compatible coating for practical application. A route to dense bioactive apatite wollastonite glass ceramics (AWGC)-polymer composites was developed. The problems associated with glass dissolution into the aqueous medium for slip casting were overcome with the use of silane. The role of heating rate and development of ceramic compact microstructure on composite properties was explored. In general, if isothermal heating was not applied, decreasing heating rate increased glass crystallinity and particle-particle fusion, but decreased pore volume. Also composite strength and fracture toughness decreased while modulus and hardness increased with decreasing heating rate. If isothermal heating was applied, glass crystallinity, pore content, and composite mechanical properties showed relatively little change regardless of the initial heating rate. The potential of AWGC-polymer composites for dental and implant applications was explored

Synthesis, characterization and potential utility of doped ceramics based catalysts

NASA Astrophysics Data System (ADS)

Sharma, Ritika; Yadav, Deepshikha; Singh, G. P.; Vyas, G.; Bhojak, N.

2018-05-01

Excessive utilization of petrol, diesel and other fossil fuels, continuous increase in their prices, and the big problem of carbon dioxide mission have encouraged scientists and technologist to find either new sources of energy or to develop technologies for the sustainable utilization of fuel. Biofuels are the only energy technologies that can resolve the problem of carbon dioxide emission in the atmosphere as well as reduce the amount of fossil fuel burned. Bio ethanol and biodiesel are the most common types of biofuel which are being used at present. Biodiesel has become more interesting for all the researchers in present scenario. Various feedstock viz. edible, nonedible oils, waste cooking oil, animal fat, algae etc, are using for the production of biodiesel worldwide according to their availability. Selection of efficient heterogeneous catalysts for biodiesel preparation still needs more attention of researchers. The present investigation deals with determination of synthesis, characterization and applications of doped ceramic based materials in different medium. Two of doped ceramic based catalysts which has been potentially used for the production of biodiesel. The Engine performance of biodiesel samples, made from industrial waste oils and ceramic based catalyst, have also been investigated and found up to satisfactory levels.

Reactive Processing of Environment Conscious, Biomorphic Ceramics: A Novel and Eco-friendly Route to Advanced Ceramic

NASA Technical Reports Server (NTRS)

Singh, M.

2002-01-01

Environment-conscious, biomorphic ceramics (Ecoceramics) are a new class of materials that can be produced with renewable resources (wood) and wood wastes (wood sawdust). These materials have tailorable properties with numerous potential applications. Silicon carbide-based ecoceramics have been fabricated by the infiltration of wood-derived carbonaceous preforms with oxide and silicon based materials. The wood-derived carbonaceous preforms have been shown to be quite useful in producing porous or dense materials with different microstructures and compositions. The microstructure and mechanical properties (flexural strength, fracture toughness, elastic modulus, and compressive strength) of a wide variety of Sic-based ecoceramics have been measured. Ecoceramics have tailorable properties and behave like ceramic materials manufactured by conventional approaches. In this presentation the fabrication approach, microstructure, and thermomechanical properties of a wide variety of Sic-based Ecoceramics will be reported.

Acoustic barriers obtained from industrial wastes.

PubMed

Garcia-Valles, M; Avila, G; Martinez, S; Terradas, R; Nogués, J M

2008-07-01

Acoustic pollution is an environmental problem that is becoming increasingly more important in our society. Likewise, the accumulation of generated waste and the need for waste management are also becoming more and more pressing. In this study we describe a new material--called PROUSO--obtained from industrial wastes. PROUSO has a variety of commercial and engineering, as well as building, applications. The main raw materials used for this environmentally friendly material come from slag from the aluminium recycling process, dust from the marble industry, foundry sands, and recycled expanded polystyrene from recycled packaging. Some natural materials, such as plastic clays, are also used. To obtain PROUSO we used a conventional ceramic process, forming new mineral phases and incorporating polluted elements into the structure. Its physical properties make PROUSO an excellent acoustic and thermal insulation material. It absorbs 95% of the sound in the frequency band of the 500 Hz. Its compressive strength makes it ideal for use in ceramic wall building.

Mercury stabilization in chemically bonded phosphate ceramics

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

Wagh, Arun S.; Jeong, Seung-Young; Singh, Dileep

1997-07-01

We have investigated mercury stabilization in chemically bonded phosphate ceramic (CBPC) using four surrogate waste streams that represent U.S. Department of Energy (DOE) ash, soil, and two secondary waste streams resulting from the destruction of DOE`s high-organic wastes by the DETOX{sup SM} Wet Oxidation Process. Hg content in the waste streams was 0.1 to 0.5 wt.% (added as soluble salts). Sulfidation of Hg and its concurrent stabilization in the CBPC matrix yielded highly nonleachable waste forms. The Toxicity Characteristic Leaching Procedure showed that leaching levels were well below the U.S. Environmental Protection Agency`s regulatory limits. The American Nuclear Society`s ANSmore » 16.1 immersion test also gave very high leaching indices, indicating excellent retention of the contaminants. In particular, leaching levels of Hg in the ash waste form were below the measurement detection limit in neutral and alkaline water, negligibly low but measureable in the first 72 h of leaching in acid water, and below the detection limit after that. These studies indicate that the waste forms are stable in a wide range of chemical environments during storage. 9 refs., 5 tabs.« less

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.

Effects of crystal refining on wear behaviors and mechanical properties of lithium disilicate glass-ceramics.

PubMed

Zhang, Zhenzhen; Guo, Jiawen; Sun, Yali; Tian, Beimin; Zheng, Xiaojuan; Zhou, Ming; He, Lin; Zhang, Shaofeng

2018-05-01

The purpose of this study is to improve wear resistance and mechanical properties of lithium disilicate glass-ceramics by refining their crystal sizes. After lithium disilicate glass-ceramics (LD) were melted to form precursory glass blocks, bar (N = 40, n = 10) and plate (N = 32, n = 8) specimens were prepared. According to the differential scanning calorimetry (DSC) of precursory glass, specimens G1-G4 were designed to form lithium disilicate glass-ceramics with different crystal sizes using a two-step thermal treatment. In the meantime, heat-pressed lithium disilicate glass-ceramics (GC-P) and original ingots (GC-O) were used as control groups. Glass-ceramics were characterized using X-ray diffraction (XRD) and were tested using flexural strength test, nanoindentation test and toughness measurements. The plate specimens were dynamically loaded in a chewing simulator with 350 N up to 2.4 × 10 6 loading cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 300,000 wear cycles. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pairwise comparisons of means were performed by Tukey's post-hoc test. Materials with different crystal sizes (p < 0.05) exhibited different properties. Specifically, G3 with medium-sized crystals presented the highest flexural strength, hardness, elastic modulus and fracture toughness. G1 and G2 with small-sized crystals showed lower flexural strength, whereas G4, GC-P, and GC-O with large-sized crystals exhibited lower hardness and elastic modulus. The wear behaviors of all six groups showed running-in wear stage and steady wear stage. G3 showed the best wear resistance while GC-P and GC-O exhibited the highest wear volume loss. After crystal refining, lithium disilicate glass-ceramic with medium-sized crystals showed the highest wear resistance and mechanical

Volatile Impurities in the Plutonium Immobilization Ceramic Wasteform

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

Cozzi, A.D.

1999-10-15

Approximately 18 of the 50 metric tons of plutonium identified for disposition contain significant quantities of impurities. A ceramic waste form is the chosen option for immobilization of the excess plutonium. The impurities associated with the stored plutonium have been identified (CaCl2, MgF2, Pb, etc.). For this study, only volatile species are investigated. The impurities are added individually. Cerium is used as the surrogate for plutonium. Three compositions, including the baseline composition, were used to verify the ability of the ceramic wasteform to accommodate impurities. The criteria for evaluation of the effect of the impurities were the apparent porosity andmore » phase assemblage of sintered pellets.« less

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.

Toxic-Waste Disposal by Drain-in-Furnace Technique

NASA Technical Reports Server (NTRS)

Compton, L. E.; Stephens, J. B.; Moynihan, P. I.; Houseman, J.; Kalvinskas, J. J.

1986-01-01

Compact furnace moved from site to site. Toxic industrial waste destroyed using furnace concept developed for disposal of toxic munitions. Toxic waste drained into furnace where incinerated immediately. In furnace toxic agent rapidly drained and destroyed in small combustion chamber between upper and lower layers of hot ceramic balls

Field-assisted sintering and phase transition of ZnS-CaLa 2S 4 composite ceramics

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

Li, Yiyu; Zhang, Lihua; Kisslinger, Kim

In the present study, zinc sulfide (ZnS) and calcium lanthanum sulfide (CaLa 2S 4, CLS) composite ceramics were consolidated via field-assisted sintering of 0.5ZnS-0.5CLS (volume ratio) composite powders at 800–1050 °C. Through sintering curve analyses and microstructural observations, it was determined that between 800 and 1000 °C, grain boundary diffusion was the main mechanism controlling grain growth for both the ZnS and CLS phases within the composite ceramics. The consolidated composite ceramics were determined to be composed of sphalerite ZnS, wurtzite ZnS and thorium phosphate CLS. The sphalerite-wurtzite phase transition of ZnS was further demonstrated to be accompanied by themore » formation of stacking faults and twins in the ceramics. Furthermore, it was also found that the addition of the CLS phase improved the indentation hardness of the ceramics relative to pure ZnS by homogeneous dispersion of ZnS and CLS small grains.« less

Field-assisted sintering and phase transition of ZnS-CaLa 2S 4 composite ceramics

DOE PAGES

Li, Yiyu; Zhang, Lihua; Kisslinger, Kim; ...

2017-07-17

In the present study, zinc sulfide (ZnS) and calcium lanthanum sulfide (CaLa 2S 4, CLS) composite ceramics were consolidated via field-assisted sintering of 0.5ZnS-0.5CLS (volume ratio) composite powders at 800–1050 °C. Through sintering curve analyses and microstructural observations, it was determined that between 800 and 1000 °C, grain boundary diffusion was the main mechanism controlling grain growth for both the ZnS and CLS phases within the composite ceramics. The consolidated composite ceramics were determined to be composed of sphalerite ZnS, wurtzite ZnS and thorium phosphate CLS. The sphalerite-wurtzite phase transition of ZnS was further demonstrated to be accompanied by themore » formation of stacking faults and twins in the ceramics. Furthermore, it was also found that the addition of the CLS phase improved the indentation hardness of the ceramics relative to pure ZnS by homogeneous dispersion of ZnS and CLS small grains.« less

Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard †

PubMed Central

Rodríguez-Robles, Desirée; García-González, Julia; Juan-Valdés, Andrés; Pozo, Julia Mª Morán-del; Guerra-Romero, Manuel I

2014-01-01

Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW. PMID:28788164

Alumina additions may improve the damage tolerance of soft machined zirconia-based ceramics.

PubMed

Oilo, Marit; Tvinnereim, Helene M; Gjerdet, Nils Roar

2011-01-01

The aim of this study was to evaluate the damage tolerance of different zirconia-based materials. Bars of one hard machined and one soft machined dental zirconia and an experimental 95% zirconia 5% alumina ceramic were subjected to 100,000 stress cycles (n = 10), indented to provoke cracks on the tensile stress side (n = 10), and left untreated as controls (n = 10). The experimental material demonstrated a higher relative damage tolerance, with a 40% reduction compared to 68% for the hard machined zirconia and 84% for the soft machined zirconia.

Yb:YAG ceramic-based laser driver for Inertial Fusion Energy (IFE)

NASA Astrophysics Data System (ADS)

Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.

2016-03-01

We report on a new class of laser amplifiers for inertial confinement fusion (ICF) drivers based on a Yb:YAG ceramic disk in an edge-pumped configuration and cooled by a high-velocity gas flow. The Yb lasant offers very high efficiency and low waste heat. The ceramic host material has a thermal conductivity nearly 15-times higher than the traditionally used glass and it is producible in sizes suitable for a typical 10- to 20-kJ driver beam line. The combination of high lasant efficiency, low waste heat, edge-pumping, and excellent thermal conductivity of the host, enable operation at 10 to 20 Hz at over 20% wall plug efficiency while being comparably smaller and less costly than recently considered face-pumped alternative drivers using Nd:glass, Yb:S-FAP, and cryogenic Yb:YAG. Scalability of the laser driver over a broad range of sizes is presented.

Fracture strength of three all-ceramic systems: Top-Ceram compared with IPS-Empress and In-Ceram.

PubMed

Quran, Firas Al; Haj-Ali, Reem

2012-03-01

The purpose of this study was to investigate the fracture loads and mode of failure of all-ceramic crowns fabricated using Top-Ceram and compare it with all-ceramic crowns fabricated from well-established systems: IPS-Empress II, In-Ceram. Thirty all-ceramic crowns were fabricated; 10 IPS-Empress II, 10 In-Ceram alumina and 10 Top-Ceram. Instron testing machine was used to measure the loads required to introduce fracture of each crown. Mean fracture load for In-Ceram alumina [941.8 (± 221.66) N] was significantly (p > 0.05) higher than those of Top-Ceram and IPS-Empress II. There was no statistically significant difference between Top-Ceram and IPS-Empress II mean fracture loads; 696.20 (+222.20) and 534 (+110.84) N respectively. Core fracture pattern was highest seen in Top- Ceram specimens.

A versatile fabrication strategy of three-dimensional foams for soft and hard tissue engineering.

PubMed

Xu, Changlu; Bai, Yanjie; Yang, Shaofeng; Yang, Huilin; Stout, David A; Tran, Phong; Yang, Lei

2017-12-15

The fabrication strategies of three-dimensional porous biomaterials have been extensively studied and well established in the past decades, yet the biocompatibility and versatility in preparing porous architecture still lacks. Herewith, we present a novel and green fabrication technique of 3D porous foams for both soft and hard engineering. By utilizing the gelatinization and retrogradation property of starches, stabilized porous constructs made of various building blocks from living cells to ceramic particles were created for the first time. In soft tissue engineering applications, 3D cultured tissue foam (CTF) with controlled release property of cells was developed and the foams constituted by osteoblasts, fibroblasts and vascular endothelial cells all exhibited high mechanical stability and preservation of cell viability or functions. More importantly, the CTF achieved sustained self-release of cells controlled by serum (containing amylase) concentration and the released cells also maintained high viability and functions. In the context of hard tissue engineering applications, ceramic/bioglass (BG) foam scaffolds were developed by the similar starch-assisted foaming strategy where the resultant bone scaffolds of hydroxyapatite (HA)/BG and Si3N4/BG possessed>70% porosity with interconnected macropores (sizes 200~400μm) and fine pores (sizes1~10 μm) and superior mechanical properties despite the high porosity. Additionally, in vitro and in vivo evaluations on the biological properties revealed that porous HA/BG foam exhibited desired biocompatibility and osteogenesis. The in vivo study indicated new bone ingrowth after 1 week and significant increases in new bone volume after 2 weeks. In conclusion, the presented foaming strategy provides opportunities for biofabricating CTF with different cells for different target soft tissues and preparing porous ceramic/BG foams with different material components and high strengths-showing great versatility in soft and

A hydrometallurgical process for recovering total metal values from waste monolithic ceramic capacitors.

PubMed

Prabaharan, G; Barik, S P; Kumar, B

2016-06-01

A hydrometallurgical process for recovering the total metal values from waste monolithic ceramic capacitors was investigated. The process parameters such as time, temperature, acid concentration, hydrogen peroxide concentration and other reagents (amount of zinc dust and sodium formate) were optimized. Base metals such as Ba, Ti, Sn, Cu and Ni are leached out in two stages using HCl in stage 1 and HCl with H2O2 in stage 2. More than 99% of leaching efficiency for base metals (Cu, Ni, Ba, Ti and Sn) was achieved. Precious metals such as Au and Pd are leached out using aquaregia and nitric acid was used for the leaching of Ag. Base metals (Ba, Ti, Sn, Cu and Ni) are recovered by selective precipitation using H2SO4 and NaOH solution. In case of precious metals, Au and Pd from the leach solution were precipitated out using sodium metabisulphite and sodium formate, respectively. Sodium chloride was used for the precipitation of Ag from leach solution. Overall recovery for base metals and precious metals are 95% and 92%, respectively. Based on the results of the present study, a process flow diagram was proposed for commercial application. Copyright © 2016 Elsevier Ltd. All rights reserved.

Systematic investigation of the strontium zirconium phosphate ceramic form for nuclear waste immobilization

NASA Astrophysics Data System (ADS)

Pet'kov, Vladimir; Asabina, Elena; Loshkarev, Vladimir; Sukhanov, Maksim

2016-04-01

We have summarized our data and literature ones on the thermophysical properties and hydrolytic stability of Sr0.5Zr2(PO4)3 compound as a host NaZr2(PO4)3-type (NZP) structure for immobilization of 90Sr-containing radioactive waste. Absence of any polymorphic transformations on the temperature dependence of its heat capacity between 7 and 665 K is caused by the stability of crystalline Sr0.5Zr2(PO4)3. Calculated values of thermal conductivity coefficients at zero porosity in the range 298-673 K were 1.86-2.40 W·m-1 K-1. The compound may be classified as low thermal expanding material due to its average linear thermal expansion coefficient. Study of the hydrolytic stability in acid and alkaline media has shown that the relative mass fraction of Sr2+ ions, released into aggressive leaching media, didn't exceed 1% of the mass of sample. Soxhlet leaching studies have shown substantial resistance towards the release of Sr2+ ions into distilled water. Feeble sinterability constrains practical applications of NZP substances, that is why known in literature methods of Sr0.5Zr2(PO4)3 dense ceramics obtaining have been reviewed.

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.

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

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

Analysis of machining damage in engineering ceramics by fracture mechanics, fractography and x-ray diffraction

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

Hollstein, T.; Pfeiffer, W.; Rombach, M.

1996-12-31

The cost for final machining covers a significant percentage of the whole cost of a ceramic component. This is due to the difficult machining of the high performance ceramics. The high values of hardness and wear resistance, which are desired in many applications, hinder the process of machining. Only a few machining procedures are applicable to engineering ceramics e.g. grinding, polishing or ultrasonic lapping, and the rate of material removal is considerably lower than for metals. In addition crack generation in the surface regions during machining is easily possible due to the brittleness of the ceramics. The material removal duringmore » grinding, which is the most important machining procedure of engineering ceramics, takes place mainly by brittle fracture processes but also by ductile material removal. The complex stress conditions in the work piece below or in the vicinity of the grinding grits lead to a variability of cracks and crack systems like median cracks, lateral cracks or radial cracks, which extend in general {le} 50 {mu}m and which lead to the strength anisotropy of ground ceramics, if certain grinding parameters are used e.g..« less

Method of making a modified ceramic-ceramic composite

DOEpatents

Weaver, Billy L.; McLaughlin, Jerry C.; Stinton, David P.

1995-01-01

The present invention provides a method of making a shaped ceramic-ceramic composite articles, such as gas-fired radiant heat burner tubes, heat exchangers, flame dispersers, and other furnace elements, having a formed-on ceramic-ceramic composite thereon.

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.

Vertically Aligned and Continuous Nanoscale Ceramic-Polymer Interfaces in Composite Solid Polymer Electrolytes for Enhanced Ionic Conductivity.

PubMed

Zhang, Xiaokun; Xie, Jin; Shi, Feifei; Lin, Dingchang; Liu, Yayuan; Liu, Wei; Pei, Allen; Gong, Yongji; Wang, Hongxia; Liu, Kai; Xiang, Yong; Cui, Yi

2018-06-13

Among all solid electrolytes, composite solid polymer electrolytes, comprised of polymer matrix and ceramic fillers, garner great interest due to the enhancement of ionic conductivity and mechanical properties derived from ceramic-polymer interactions. Here, we report a composite electrolyte with densely packed, vertically aligned, and continuous nanoscale ceramic-polymer interfaces, using surface-modified anodized aluminum oxide as the ceramic scaffold and poly(ethylene oxide) as the polymer matrix. The fast Li + transport along the ceramic-polymer interfaces was proven experimentally for the first time, and an interfacial ionic conductivity higher than 10 -3 S/cm at 0 °C was predicted. The presented composite solid electrolyte achieved an ionic conductivity as high as 5.82 × 10 -4 S/cm at the electrode level. The vertically aligned interfacial structure in the composite electrolytes enables the viable application of the composite solid electrolyte with superior ionic conductivity and high hardness, allowing Li-Li cells to be cycled at a small polarization without Li dendrite penetration.

Portfolio: Ceramics.

ERIC Educational Resources Information Center

Hardy, Jane; And Others

1982-01-01

Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

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.

Effect of ZrO(2) additions on the crystallization, mechanical and biological properties of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics.

PubMed

Li, H C; Wang, D G; Meng, X G; Chen, C Z

2014-06-01

A series of ZrO(2) doped MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics were obtained by sintering method. The crystallization behavior, phase composition, morphology and structure of glass-ceramics were characterized. The bending strength, elastic modulus, fracture toughness, micro-hardness and thermal expansion coefficient (TEC) of glass-ceramics were investigated. The in vitro bioactivity and cytotoxicity tests were used to evaluate the bioactivity and biocompatibility of glass-ceramics. The sedimentation mechanism and growth process of apatites on sample surface were discussed. The results showed that the mainly crystalline phases of glass-ceramics were Ca(5)(PO4)3F (fluorapatite) and β-CaSiO(3). (β-wollastonite). m-ZrO(2) (monoclinic zirconia) declined the crystallization temperatures of glasses. t-ZrO(2) (tetragonal zirconia) increased the crystallization temperature of Ca(5)(PO4)(3)F and declined the crystallization temperature of β-CaSiO(3). t-ZrO(2) greatly increased the fracture toughness, bending strength and micro-hardness of glass-ceramics. The nanometer apatites were induced on the surface of glass-ceramic after soaking 28 days in SBF (simulated body fluid), indicating the glass-ceramic has good bioactivity. The in vitro cytotoxicity test demonstrated the glass-ceramic has no toxicity to cell. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental and numerical investigations on the temperature distribution in PVD AlTiN coated and uncoated Al2O3/TiCN mixed ceramic cutting tools in hard turning of AISI 52100 steel

NASA Astrophysics Data System (ADS)

Sateesh Kumar, Ch; Patel, Saroj Kumar; Das, Anshuman

2018-03-01

Temperature generation in cutting tools is one of the major causes of tool failure especially during hard machining where machining forces are quite high resulting in elevated temperatures. Thus, the present work investigates the temperature generation during hard machining of AISI 52100 steel (62 HRC hardness) with uncoated and PVD AlTiN coated Al2O3/TiCN mixed ceramic cutting tools. The experiments were performed on a heavy duty lathe machine with both coated and uncoated cutting tools under dry cutting environment. The temperature of the cutting zone was measured using an infrared thermometer and a finite element model has been adopted to predict the temperature distribution in cutting tools during machining for comparative assessment with the measured temperature. The experimental and numerical results revealed a significant reduction of cutting zone temperature during machining with PVD AlTiN coated cutting tools when compared to uncoated cutting tools during each experimental run. The main reason for decrease in temperature for AlTiN coated tools is the lower coefficient of friction offered by the coating material which allows the free flow of the chips on the rake surface when compared with uncoated cutting tools. Further, the superior wear behaviour of AlTiN coating resulted in reduction of cutting temperature.

The effect of colouring agent on the physical properties of glass ceramic produced from waste glass for antimicrobial coating deposition

NASA Astrophysics Data System (ADS)

Juoi, J. M.; Ayoob, N. F.; Rosli, Z. M.; Rosli, N. R.; Husain, K.

2016-07-01

Domestic waste glass is utilized as raw material for the production of glass ceramic material (GCM) via sinter crystallisation route. The glass ceramic material in a form of tiles is to be utilized for the deposition of Ag-TiO2 antimicrobial coating. Two types of soda lime glass (SLG) that are non-coloured and green SLG are utilised as main raw materials during the batch formulation in order to study the effect of colouring agent (Fe2O3) on the physical and mechanical properties of glass ceramic produced. Glass powder were prepared by crushing bottles using hammer milled with milling machine and sieved until they passed through 75 µm sieve. The process continues by mixing glass powder with ball clay with ratio of 95:5 wt. %, 90:10 wt. % and 85:15 wt. %. Each batch mixture was then uniaxial pressed and sintered at 800°C, 825 °C and 850 °C. The physical and mechanical properties were then determined and compared between those produced from non-coloured and green coloured SLG in order to evaluate the effect of colouring agent (Fe2O3) on the GCM produced. The optimum properties of non-coloured SLG is produced with smaller ball clay content (10 wt. %) compared to green SLG (15 wt. %). The physical properties (determined thru ASTM C373) of the optimized GCM produced from non-coloured SLG and green SLG are 0.69 % of porosity, 1.92 g/cm3 of bulk density, 0.36 % of water absorption; and 1.96 % of porosity, 2.69 g/cm3 of bulk density, 0.73 % of water absorption; respectively. Results also indicate that the most suitable temperature in producing GCM from both glasses with optimized physical and mechanical properties is at 850 °C.

Possible applications for municipal solid waste fly ash.

PubMed

Ferreira, C; Ribeiro, A; Ottosen, L

2003-01-31

The present study focuses on existing practices related to the reuse of Municipal Solid Waste (MSW) fly ash and identifies new potential uses. Nine possible applications were identified and grouped into four main categories: construction materials (cement, concrete, ceramics, glass and glass-ceramics); geotechnical applications (road pavement, embankments); "agriculture" (soil amendment); and, miscellaneous (sorbent, sludge conditioning). Each application is analysed in detail, including final-product technical characteristics, with a special emphasis on environmental impacts. A comparative analysis of the different options is performed, stressing the advantages but also the weaknesses of each option. This information is systemized in order to provide a framework for the selection of best technology and final products. The results presented here show new possibilities for this waste reuse in a short-term, in a wide range of fields, resulting in great advantages in waste minimization as well as resources conservation.

Ceramic tools insert assesment based on vickers indentation methodology

NASA Astrophysics Data System (ADS)

Husni; Rizal, Muhammad; Aziz M, M.; Wahyu, M.

2018-05-01

In the interrupted cutting process, the risk of tool chipping or fracture is higher than continues cutting. Therefore, the selection of suitable ceramic tools for interrupted cutting application become an important issue to assure that the cutting process is running effectively. At present, the performance of ceramics tools is assessed by conducting some cutting tests, which is required time and cost consuming. In this study, the performance of ceramic tools evaluated using hardness tester machine. The technique, in general, has a certain advantage compare with the more conventional methods; the experimental is straightforward involving minimal specimen preparation and the amount of material needed is small. Three types of ceramic tools AS10, CC650 and K090 have been used, each tool was polished then Vickers indentation test were performed with the load were 0.2, 0.5, 1, 2.5, 5 and 10 kgf. The results revealed that among the load used in the tests, the indentation loads of 5 kgf always produce well cracks as compared with others. Among the cutting tool used in the tests, AS10 has produced the shortest crack length and follow by CC 670, and K090. It is indicated that the shortest crack length of AS10 reflected that the tool has a highest dynamic load resistance among others insert.

Ceramics: Durability and radiation effects

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

Ewing, R.C.; Lutze, W.; Weber, W.J.

1996-05-01

At present, there are three seriously considered options for the disposition of excess weapons plutonium: (1) incorporation, partial burn-up and direct disposal of MOX-fuel; (2) vitrification with defense waste and disposal as glass {open_quotes}logs{close_quotes}; (3) deep borehole disposal. The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramicsmore » apatite, pyrochlore, zirconolite, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.« less

Assessment of the State of the Art of Ultra High Temperature Ceramics

NASA Technical Reports Server (NTRS)

Johnson, Sylvia; Gasch, Matt; Stackpoole, Mairead

2009-01-01

Ultra High Temperature Ceramics (UHTCs) are a family of materials that includes the borides, carbides and nitrides of hafnium-, zirconium- and titanium-based systems. UHTCs are famous for possessing some of the highest melting points of known materials. In addition, they are very hard, have good wear resistance, mechanical strength, and relatively high thermal conductivities (compared to other ceramic materials). Because of these attributes, UHTCs are ideal for thermal protection systems, especially those that require chemical and structural stability at extremely high operating temperatures. UHTCs have the potential to revolutionize the aerospace industry by enabling the development of sharp hypersonic vehicles or atmospheric entry probes capable of the most extreme entry conditions.

Roadmap for disposal of Electrorefiner Salt as Transuranic Waste.

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

Rechard, Robert P.; Trone, Janis R.; Kalinina, Elena Arkadievna

The experimental breeder reactor (EBR-II) used fuel with a layer of sodium surrounding the uranium-zirconium fuel to improve heat transfer. Disposing of EBR-II fuel in a geologic repository without treatment is not prudent because of the potentially energetic reaction of the sodium with water. In 2000, the US Department of Energy (DOE) decided to treat the sodium-bonded fuel with an electrorefiner (ER), which produces metallic uranium product, a metallic waste, mostly from the cladding, and the salt waste in the ER, which contains most of the actinides and fission products. Two waste forms were proposed for disposal in a minedmore » repository; the metallic waste, which was to be cast into ingots, and the ER salt waste, which was to be further treated to produce a ceramic waste form. However, alternative disposal pathways for metallic and salt waste streams may reduce the complexity. For example, performance assessments show that geologic repositories can easily accommodate the ER salt waste without treating it to form a ceramic waste form. Because EBR-II was used for atomic energy defense activities, the treated waste likely meets the definition of transuranic waste. Hence, disposal at the Waste Isolation Pilot Plant (WIPP) in southern New Mexico, may be feasible. This report reviews the direct disposal pathway for ER salt waste and describes eleven tasks necessary for implementing disposal at WIPP, provided space is available, DOE decides to use this alternative disposal pathway in an updated environmental impact statement, and the State of New Mexico grants permission.« less

Effects of soldering and laser welding on bond strength of ceramic to metal.

PubMed

Aladağ, Akin; Cömlekoğlu, M Erhan; Dündar, Mine; Güngör, M Ali; Artunç, Celal

2011-01-01

Welding or soldering of metal frameworks negatively affects the overall bond strength between the veneering ceramic and metal. The purpose of this study was to evaluate the effect of soldering and laser-welding procedures on the bond strength between ceramic and metal. Thirty Ni-based metal specimens (Wiron 99) (8 × 4 × 4 mm) were fabricated and divided into 3 groups; soldered (S), laser welded (L), and control (untreated cast alloy) (n=10). In S and L specimens, a notch (1 × 1.5 mm) was prepared longitudinally on the surface of each specimen and filled with compatible alloy (Wiron soldering rods and Wiroweld NC, respectively). Vickers hardness measurements were made after polishing the surfaces with a metallographic polishing kit. A veneering ceramic (VITA VMK 95) was vibrated, condensed in a mold, and fired on the metal frameworks. The specimens were sectioned in 2 axes to obtain nontrimmed bar specimens with a bonding area of approximately 1 mm². Forty bars per block were obtained. Each bar was subjected to microtensile bond strength (μTBS) testing with a crosshead speed of 1 mm/min. The μTBS data (MPa) were recorded, and SEM was used for failure analysis of the tested bars. The measurements were statistically analyzed using a 1-way ANOVA and Tamhane tests (α=.05). The mean differences in μTBS of veneering ceramic to soldered (10.4 ±2.4 MPa) and laser-welded (11.7 ±1.3 MPa) metal surfaces were not significantly different and were significantly lower than that of the cast alloy (25.4 ±3.6 MPa) (P<.05). The mean Vickers hardness of cast alloy was significantly higher (236 ±17 HV) than soldered (114 ±9 HV) and laser-welded groups (129 ±11 HV) (P<.05). Soldering and laser welding significantly decreased the μTBS of a veneering ceramic to a base metal alloy. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Structural Ceramics Database

National Institute of Standards and Technology Data Gateway

SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

Preparation of affordable and multifunctional clay-based ceramic filter matrix for treatment of drinking water.

PubMed

Shivaraju, H Puttaiah; Egumbo, Henok; Madhusudan, P; Anil Kumar, K M; Midhun, G

2018-02-01

Affordable clay-based ceramic filters with multifunctional properties were prepared using low-cost and active ingredients. The characterization results clearly revealed well crystallinity, structural elucidation, extensive porosity, higher surface area, higher stability, and durability which apparently enhance the treatment efficiency. The filtration rates of ceramic filter were evaluated under gravity and the results obtained were compared with a typical gravity slow sand filter (GSSF). All ceramic filters showed significant filtration rates of about 50-180 m/h, which is comparatively higher than the typical GSSF. Further, purification efficiency of clay-based ceramic filters was evaluated by considering important drinking water parameters and contaminants. A significant removal potential was achieved by the clay-based ceramic filter with 25% and 30% activated carbon along with active agents. Desired drinking water quality parameters were achieved by potential removal of nitrite (98.5%), nitrate (80.5%), total dissolved solids (62%), total hardness (55%), total organic pollutants (89%), and pathogenic microorganisms (100%) using ceramic filters within a short duration. The remarkable purification and disinfection efficiencies were attributed to the extensive porosity (0.202 cm 3  g -1 ), surface area (124.61 m 2  g -1 ), stability, and presence of active nanoparticles such as Cu, TiO 2 , and Ag within the porous matrix of the ceramic filter.

Metal-Ceramic composites via “in situ” methods

NASA Astrophysics Data System (ADS)

Florea, R. M.

2017-08-01

Several “in situ” methods for obtaining composite materials with ceramic particles were developed in order to overcome some of the inherent problems associated with conventional processes. This paper reviews the obtaining processes of composite materials with a greater emphasis on nitriding and oxidation by directed melting. These obtaining methods provide microstructures with different combinations of metal-ceramic. Metal matrix composites with controlled amounts of dispersed ceramic particles are obtained by “in situ” processes. The composite materials obtained are having different properties by controlling various processing variables such as temperature, time, the reactant phases and the reinforcing material. The properties of the “in situ” obtained materials depend mainly on the matrix and volume fraction of constituent phase. Briefly are reviewed the mechanical properties, hardness mechanisms and possible applications of these composite materials. Nitridation is much more attractive because with the variation of process parameters is obtained a wider range of microstructures and properties. The activation energy for the formation of AlN (A1N ˜ 100 kJ/mole) is smaller than that of oxidation (Al2O3 ˜ 400 kJ/mole) and growth rates (3 × 10-2 gm/cm2/s) are at least three times higher for oxidation.

Mechanical properties of polymer-infiltrated-ceramic (sodium aluminum silicate) composites for dental restoration.

PubMed

Cui, Bencang; Li, Jing; Wang, Huining; Lin, Yuanhua; Shen, Yang; Li, Ming; Deng, Xuliang; Nan, Cewen

2017-07-01

To fabricate indirect restorative composites for CAD/CAM applications and evaluate the mechanical properties. Polymer-infiltrated-ceramic composites were prepared through infiltrating polymer into partially sintered sodium aluminum silicate ceramic blocks and curing. The corresponding samples were fabricated according to standard ISO-4049 using for mechanical properties measurement. The flexural strength and fracture toughness were measured using a mechanical property testing machine. The Vickers hardness and elastic modulus were calculated from the results of nano-indentation. The microstructures were investigated using secondary electron detector. The density of the porous ceramic blocks was obtained through TG-DTA. The conversion degrees were calculated from the results of mid-infrared spectroscopy. The obtained polymer infiltrated composites have a maximum flexural strength value of 214±6.5MPa, Vickers hardness of 1.76-2.30GPa, elastic modulus of 22.63-27.31GPa, fracture toughness of 1.76-2.35MPam 1/2 and brittleness index of 0.75-1.32μm -1/2 . These results were compared with those of commercial CAD/CAM blocks. Our results suggest that these materials with good mechanical properties are comparable to two commercial CAD/CAM blocks. The sintering temperature could dramatically influence the mechanical properties. Restorative composites with superior mechanical properties were produced. These materials mimic the properties of natural dentin and could be a promising candidate for CAD/CAM applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Failure of a novel ceramic-on-ceramic hip resurfacing prosthesis.

PubMed

Matharu, Gulraj S; Daniel, Joseph; Ziaee, Hena; McMinn, Derek J W

2015-03-01

We report the early failure of five ceramic-on-ceramic hip resurfacings (CoCHRs). The ceramic used for the acetabular liner was a novel ceramic-composite (two thirds polyurethane and one third alumina ceramic). All cases were revised for increasing metal ion levels (blood cobalt 3.93-208.0 μg/l and chromium 1.57-17.5 μg/l) due to ceramic liner fracture and/or accelerated wear of the ceramic femoral head coating. Patients underwent bearing exchange and revision using primary hip arthroplasty implants at a mean of 3.0 years following CoCHR. Intraoperatively all patients had metallosis. At 1 to 2 years of follow-up blood metal ions normalized with no complications. We do not recommend this particular type of ceramic-on-ceramic bearing for hip resurfacing. Copyright © 2014 Elsevier Inc. All rights reserved.

Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes

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

Indacochea, J. E.; Gattu, V. K.; Chen, X.

The results of electrochemical corrosion tests and modeling activities performed collaboratively by researchers at the University of Illinois at Chicago and Argonne National Laboratory as part of workpackage NU-13-IL-UIC-0203-02 are summarized herein. The overall objective of the project was to develop and demonstrate testing and modeling approaches that could be used to evaluate the use of composite alloy/ceramic materials as high-level durable waste forms. Several prototypical composite waste form materials were made from stainless steels representing fuel cladding, reagent metals representing metallic fuel waste streams, and reagent oxides representing oxide fuel waste streams to study the microstructures and corrosion behaviorsmore » of the oxide and alloy phases. Microelectrodes fabricated from small specimens of the composite materials were used in a series of electrochemical tests to assess the corrosion behaviors of the constituent phases and phase boundaries in an aggressive acid brine solution at various imposed surface potentials. The microstructures were characterized in detail before and after the electrochemical tests to relate the electrochemical responses to changes in both the electrode surface and the solution composition. The results of microscopic, electrochemical, and solution analyses were used to develop equivalent circuit and physical models representing the measured corrosion behaviors of the different materials pertinent to long-term corrosion behavior. This report provides details regarding (1) the production of the composite materials, (2) the protocol for the electrochemical measurements and interpretations of the responses of multi-phase alloy and oxide composites, (3) relating corrosion behaviors to microstructures of multi-phase alloys based on 316L stainless steel and HT9 (410 stainless steel was used as a substitute) with added Mo, Ni, and/or Mn, and (4) modeling the corrosion behaviors and rates of several alloy/oxide composite

Status of plutonium ceramic immobilization processes and immobilization forms

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

Ebbinghaus, B.B.; Van Konynenburg, R.A.; Vance, E.R.

1996-05-01

Immobilization in a ceramic followed by permanent emplacement in a repository or borehole is one of the alternatives currently being considered by the Fissile Materials Disposition Program for the ultimate disposal of excess weapons-grade plutonium. To make Pu recovery more difficult, radioactive cesium may also be incorporated into the immobilization form. Valuable data are already available for ceramics form R&D efforts to immobilize high-level and mixed wastes. Ceramics have a high capacity for actinides, cesium, and some neutron absorbers. A unique characteristic of ceramics is the existence of mineral analogues found in nature that have demonstrated actinide immobilization over geologicmore » time periods. The ceramic form currently being considered for plutonium disposition is a synthetic rock (SYNROC) material composed primarily of zirconolite (CaZrTi{sub 2}O{sub 7}), the desired actinide host phase, with lesser amounts of hollandite (BaAl{sub 2}Ti{sub 6}O{sub 16}) and rutile (TiO{sub 2}). Alternative actinide host phases are also being considered. These include pyrochlore (Gd{sub 2}Ti{sub 2}O{sub 7}), zircon (ZrSiO{sub 4}), and monazite (CePO{sub 4}), to name a few of the most promising. R&D activities to address important technical issues are discussed. Primarily these include moderate scale hot press fabrications with plutonium, direct loading of PuO{sub 2} powder, cold press and sinter fabrication methods, and immobilization form formulation issues.« less

Recycling of inorganic waste in monolithic and cellular glass-based materials for structural and functional applications.

PubMed

Rincón, Acacio; Marangoni, Mauro; Cetin, Suna; Bernardo, Enrico

2016-07-01

The stabilization of inorganic waste of various nature and origin, in glasses, has been a key strategy for environmental protection for the last decades. When properly formulated, glasses may retain many inorganic contaminants permanently, but it must be acknowledged that some criticism remains, mainly concerning costs and energy use. As a consequence, the sustainability of vitrification largely relies on the conversion of waste glasses into new, usable and marketable glass-based materials, in the form of monolithic and cellular glass-ceramics. The effective conversion in turn depends on the simultaneous control of both starting materials and manufacturing processes. While silica-rich waste favours the obtainment of glass, iron-rich wastes affect the functionalities, influencing the porosity in cellular glass-based materials as well as catalytic, magnetic, optical and electrical properties. Engineered formulations may lead to important reductions of processing times and temperatures, in the transformation of waste-derived glasses into glass-ceramics, or even bring interesting shortcuts. Direct sintering of wastes, combined with recycled glasses, as an example, has been proven as a valid low-cost alternative for glass-ceramic manufacturing, for wastes with limited hazardousness. The present paper is aimed at providing an up-to-date overview of the correlation between formulations, manufacturing technologies and properties of most recent waste-derived, glass-based materials. © 2016 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of Fe2O3 on the properties of ceramics from steel slag

NASA Astrophysics Data System (ADS)

Li, Yu; Zhao, Li-hua; Wang, Ya-kun; Cang, Da-qiang

2018-04-01

Ferric oxide is one of the key factors affecting both the microstructure and the properties of CaO-MgO-SiO2-based ceramics. Research on this effect is significant in the utilization of iron-rich solid wastes in ceramics. Ceramic samples with various Fe2O3 contents (0wt%, 5wt%, and 10wt%) were prepared and the corresponding physical properties and microstructure were studied. The results indicated that Fe2O3 not only played a fluxing role, but also promoted the formation of crystals. Ceramics with 5wt% of Fe2O3 addition attained the best mechanical properties with a flexural strength of 132.9 MPa. Iron ions were dissolved into diopside, consequently causing phase transformation from diopside and protoenstatite to augite, thereby contributing to the enhancement of its properties. An excess amount of Fe2O3 addition (10wt% or more) resulted in deteriorated properties due to the generation of an excess volume of liquid and the formation of high-porosity structures within ceramics.

Applications in the Nuclear Industry for Thermal Spray Amorphous Metal and Ceramic Coatings

NASA Astrophysics Data System (ADS)

Blink, J.; Farmer, J.; Choi, J.; Saw, C.

2009-06-01

Amorphous metal and ceramic thermal spray coatings have been developed with excellent corrosion resistance and neutron absorption. These coatings, with further development, could be cost-effective options to enhance the corrosion resistance of drip shields and waste packages, and limit nuclear criticality in canisters for the transportation, aging, and disposal of spent nuclear fuel. Iron-based amorphous metal formulations with chromium, molybdenum, and tungsten have shown the corrosion resistance believed to be necessary for such applications. Rare earth additions enable very low critical cooling rates to be achieved. The boron content of these materials and their stability at high neutron doses enable them to serve as high efficiency neutron absorbers for criticality control. Ceramic coatings may provide even greater corrosion resistance for waste package and drip shield applications, although the boron-containing amorphous metals are still favored for criticality control applications. These amorphous metal and ceramic materials have been produced as gas-atomized powders and applied as near full density, nonporous coatings with the high-velocity oxy-fuel process. This article summarizes the performance of these coatings as corrosion-resistant barriers and as neutron absorbers. This article also presents a simple cost model to quantify the economic benefits possible with these new materials.

Stretch-and-release fabrication, testing and optimization of a flexible ceramic armor inspired from fish scales.

PubMed

Martini, Roberto; Barthelat, Francois

2016-10-13

Protective systems that are simultaneously hard to puncture and compliant in flexion are desirable, but difficult to achieve because hard materials are usually stiff. However, we can overcome this conflicting design requirement by combining plates of a hard material with a softer substrate, and a strategy which is widely found in natural armors such as fish scales or osteoderms. Man-made segmented armors have a long history, but their systematic implementation in a modern and a protective system is still hampered by a limited understanding of the mechanics and the design of optimization guidelines, and by challenges in cost-efficient manufacturing. This study addresses these limitations with a flexible bioinspired armor based on overlapping ceramic scales. The fabrication combines laser engraving and a stretch-and-release method which allows for fine tuning of the size and overlap of the scales, and which is suitable for large scale fabrication. Compared to a continuous layer of uniform ceramic, our fish-scale like armor is not only more flexible, but it is also more resistant to puncture and more damage tolerant. The proposed armor is also about ten times more puncture resistant than soft elastomers, making it a very attractive alternative to traditional protective equipment.

Process for making a titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.

1992-01-01

A ceramic composition composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to aobut 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness.

Process for making a titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition

DOEpatents

Holcombe, C.E.; Dykes, N.L.

1992-04-28

A ceramic composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to about 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness. No Drawings

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.

Joining engineering ceramics

NASA Astrophysics Data System (ADS)

Loehman, Ronald E.

Methods for joining ceramics are outlined with attention given to their fundamental properties, and some examples of ceramic bonding in engineering ceramic systems are presented. Ceramic-ceramic bonds using no filler material include diffusion and electric-field bonding and ceramic welding, and bonds with filler materials can be provided by Mo-Mn brazing, microwave joining, and reactive nonmetallic liquid bonding. Ceramic-metal joints can be effected with filler material by means of the same ceramic-ceramic processes and without filler material by means of use of molten glass or diffusion bonding. Key properties of the bonding processes include: bonds with discontinuous material properties, energies that are positive relative to the bulk material, and unique chemical and mechanical properties. The processes and properties are outlined for ceramic-metal joints and for joining silicon nitride, and the factors that control wetting, adhesion, and reaction on the atomic scale are critical for establishing successful joints.

Synthesis, characterization and bioactivity of a calcium-phosphate glass-ceramics obtained by the sol-gel processing method.

PubMed

Jmal, Nouha; Bouaziz, Jamel

2017-02-01

In this work, a calcium-phosphate glass-ceramics was successfully obtained by heat treatment of a mixture of 26.52 in wt.% of fluorapatite (Fap) and 73.48 in wt.% of 77S (77 SiO 2 14 CaO9 P 2 O 5 in wt.%) gel. The calcium phosphate-glass-ceramics was prepared by sol-gel process with tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate and fluorapatite. The synthesized powders were characterized by some commonly used tools such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), 31 P magic angle spinning nuclear magnetic resonance (MAS-NMR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thin-film X-ray diffraction (TF-XRD). The obtained results seemed to confirm the nucleation and growth of hydroxyapatite (Hap) nano-phase in the glass. Moreover, an in-vitro evaluation of the glass-ceramic was performed. In addition, to assess its bioactive capacity, it was soaked in simulated body fluid (SBF) at different time intervals. The SEM, EDS and TF-XRD analyses showed the deposition of hydroxyapatite on the surface of the specimens after three days of immersion in SBF solution. The mechanical properties of the obtained material such as rupture strength, Vickers hardness and elastic modulus were measured. In addition, the friction coefficient of calcium phosphate-glass-ceramics was tested. The values of the composite of rupture strength (24MPa), Vickers hardness (214Hv), Young's modulus (52.3GPa), shear modulus (19GPa) and friction coefficient (0.327) were obtained. This glass-ceramics can have useful applications in dental prostheses. Indeed, this material may have promising applications for implants because of its content of fluorine, the effective protector against dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

[Effect of sintering temperature on mechanical properties of dental zirconia toughened alumina ceramics].

PubMed

Fan, Jiang-Yuan; Lin, Ting-Ting; Hu, Fang-Xuan; Zheng, Rui-Bin; Fan, Fan; Ma, Jian-Feng

2017-04-01

To investigate the effect of sintering temperature on mechanical properties of dental zirconia toughened alumina (ZTA) ceramics prepared by gel-casting technique. The samples prepared by gel-casting were sintered at 1100, 1200, 1250, 1300 and 1400degrees centigrade for each group. The flexural strength, fracture toughness, Vickers hardness and brittleness index were obtained and microscopic morphology of each group was observed under scanning electron microscope (SEM). The data were statistically analyzed using SPSS 19.0 software package. The flexural strength, fracture toughness and Vickers hardness increased with the increasing sintering temperature during 1100~1400degrees centigrade. The lowest brittleness index (0.74±0.16) μm -1/2 was observed in group sintered at 1200degrees centigrade and the highest (2.76±0.14) μm -1/2 was at 1400degrees centigrade (P<0.05), while the flexural strength of these two groups was (46.89±3.24) MPa and (349.64±54.72) MPa, respectively. The ZTA dental ceramics exhibit good machinability with proper sintering temperature (1200degrees centigrade) and the strength meets the requirement of clinical application.

Fabrication and characterization of fine ceramic based on alumina, bentonite, and glass bead

NASA Astrophysics Data System (ADS)

Sebayang, P.; Nurdina; Simbolon, S.; Kurniawan, C.; Yunus, M.; Setiadi, E. A.; Sitorus, Z.

2018-03-01

Fabrication of fine ceramics based on alumina, bentonite and glass bead has been carried out by powder metallurgy. The preparation of powder has been performed using High Energy Milling (HEM) with wet milling process and using toluene as medium for 2 hours. The powder milling result was dried in oven at 100 °C for 24 hours. After that, the powder was compacted into pellet by using hydraulic press with 80 kgf/cm2 pressure at room temperature. Then, the pellet was sintered at 900 °C for 4 hours. Materials characterization such as physical properties (true density, bulk density, porosity, and water absorption), average particle diameter, hardness, microstructure and phase were measured by Archimedes method, Particle Size Analyzer (PSA), Hardness Vickers (HV), Scanning Electron Microscope (SEM-EDX) and X-Ray Diffraction (XRD). From the result, the optimum condition is sample D (with addition of 30 wt.% γ-Al2O3) with sintering temperature of 900 °C for 4 hours. At this condition, these properties were measured: average particle diameter of 4.27 μm, true density of 2.32 g/cm3, porosity of 5.57%, water absorption of 2.46%, bulk density of 2.39 g/cm3, and hardness of 632 HV. The fine ceramic has four phases with albite (Al2NaO8Si3) and quartz (SiO2) as dominant phases and corundum (Al2O3) and nepheline (AlNaO4Si) as minor phases.

Final report on cermet high-level waste forms

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

Kobisk, E.H.; Quinby, T.C.; Aaron, W.S.

1981-08-01

Cermets are being developed as an alternate method for the fixation of defense and commercial high level radioactive waste in a terminal disposal form. Following initial feasibility assessments of this waste form, consisting of ceramic particles dispersed in an iron-nickel base alloy, significantly improved processing methods were developed. The characterization of cermets has continued through property determinations on samples prepared by various methods from a variety of simulated and actual high-level wastes. This report describes the status of development of the cermet waste form as it has evolved since 1977. 6 tables, 18 figures.

A new classification system for all-ceramic and ceramic-like restorative materials.

PubMed

Gracis, Stefano; Thompson, Van P; Ferencz, Jonathan L; Silva, Nelson R F A; Bonfante, Estevam A

2015-01-01

Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

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

Polishing of silicon based advanced ceramics

NASA Astrophysics Data System (ADS)

Klocke, Fritz; Dambon, Olaf; Zunke, Richard; Waechter, D.

2009-05-01

Silicon based advanced ceramics show advantages in comparison to other materials due to their extreme hardness, wear and creep resistance, low density and low coefficient of thermal expansion. As a matter of course, machining requires high efforts. In order to reach demanded low roughness for optical or tribological applications a defect free surface is indispensable. In this paper, polishing of silicon nitride and silicon carbide is investigated. The objective is to elaborate scientific understanding of the process interactions. Based on this knowledge, the optimization of removal rate, surface quality and form accuracy can be realized. For this purpose, fundamental investigations of polishing silicon based ceramics are undertaken and evaluated. Former scientific publications discuss removal mechanisms and wear behavior, but the scientific insight is mainly based on investigations in grinding and lapping. The removal mechanisms in polishing are not fully understood due to complexity of interactions. The role of, e.g., process parameters, slurry and abrasives, and their influence on the output parameters is still uncertain. Extensive technological investigations demonstrate the influence of the polishing system and the machining parameters on the stability and the reproducibility. It is shown that the interactions between the advanced ceramics and the polishing systems is of great relevance. Depending on the kind of slurry and polishing agent the material removal mechanisms differ. The observed effects can be explained by dominating mechanical or chemo-mechanical removal mechanisms. Therefore, hypotheses to state adequate explanations are presented and validated by advanced metrology devices, such as SEM, AFM and TEM.

Ceramic Laser Materials

PubMed Central

Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

2012-01-01

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

Study on electroplating technology of diamond tools for machining hard and brittle materials

NASA Astrophysics Data System (ADS)

Cui, Ying; Chen, Jian Hua; Sun, Li Peng; Wang, Yue

2016-10-01

With the development of the high speed cutting, the ultra-precision machining and ultrasonic vibration technique in processing hard and brittle material , the requirement of cutting tools is becoming higher and higher. As electroplated diamond tools have distinct advantages, such as high adaptability, high durability, long service life and good dimensional stability, the cutting tools are effective and extensive used in grinding hard and brittle materials. In this paper, the coating structure of electroplating diamond tool is described. The electroplating process flow is presented, and the influence of pretreatment on the machining quality is analyzed. Through the experimental research and summary, the reasonable formula of the electrolyte, the electroplating technologic parameters and the suitable sanding method were determined. Meanwhile, the drilling experiment on glass-ceramic shows that the electroplating process can effectively improve the cutting performance of diamond tools. It has laid a good foundation for further improving the quality and efficiency of the machining of hard and brittle materials.

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.

[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.

High temperature resistant cermet and ceramic compositions

NASA Technical Reports Server (NTRS)

Phillips, W. M. (Inventor)

1978-01-01

Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

Concept for Underground Disposal of Nuclear Waste

NASA Technical Reports Server (NTRS)

Bowyer, J. M.

1987-01-01

Packaged waste placed in empty oil-shale mines. Concept for disposal of nuclear waste economically synergistic with earlier proposal concerning backfilling of oil-shale mines. New disposal concept superior to earlier schemes for disposal in hard-rock and salt mines because less uncertainty about ability of oil-shale mine to contain waste safely for millenium.

Oxidation and Corrosion of Ceramics and Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Opila, Elizabeth J.; Lee, Kang N.

2000-01-01

Ceramics and ceramic matrix composites are candidates for numerous applications in high temperature environments with aggressive gases and possible corrosive deposits. There is a growing realization that high temperature oxidation and corrosion issues must be considered. There are many facets to these studies, which have been extensively covered in some recent reviews. The focus of this paper is on current research, over the past two years. In the authors' view, the most important oxidation and corrosion studies have focused on four major areas during this time frame. These are; (I) Oxidation of precursor-based ceramics; (II) Studies of the interphase material in ceramic matrix composites; (III) Water vapor interactions with ceramics, particularly in combustion environments; and (IV) Development of refractory oxide coatings for silicon-based ceramics. In this paper, we shall explore the most current work in each of these areas.

Effect of sintering temperature on physical, structural and optical properties of wollastonite based glass-ceramic derived from waste soda lime silica glasses

NASA Astrophysics Data System (ADS)

Almasri, Karima Amer; Sidek, Hj. Ab Aziz; Matori, Khamirul Amin; Zaid, Mohd Hafiz Mohd

The impact of different sintering temperatures on physical, optical and structural properties of wollastonite (CaSiO3) based glass-ceramics were investigated for its potential application as a building material. Wollastonite based glass-ceramics was provided by a conventional melt-quenching method and followed by a controlled sintering process. In this work, soda lime silica glass waste was utilized as a source of silicon. The chemical composition and physical properties of glass were characterized by using Energy Dispersive X-ray Fluorescence (EDXRF) and Archimedes principle. The Archimedes measurement results show that the density increased with the increasing of sintering temperature. The generation of CaSiO3, morphology, size and crystal phase with increasing the heat-treatment temperature were examined by field emission scanning electron microscopy (FESEM), Fourier transforms infrared reflection spectroscopy (FTIR), and X-ray diffraction (XRD). The average calculated crystal size gained from XRD was found to be in the range 60 nm. The FESEM results show a uniform distribution of particles and the morphology of the wollastonite crystal is in relict shapes. The appearance of CaO, SiO2, and Ca-O-Si bands disclosed from FTIR which showed the formation of CaSiO3 crystal phase. In addition to the calculation of the energy band gap which found to be increased with increasing sintering temperature.

Novel sintered ceramic materials incorporated with EAF carbon steel slag

NASA Astrophysics Data System (ADS)

Karayannis, V.; Ntampegliotis, K.; Lamprakopoulos, S.; Papapolymerou, G.; Spiliotis, X.

2017-01-01

In the present research, novel sintered clay-based ceramic materials containing electric arc furnace carbon steel slag (EAFC) as a useful admixture were developed and characterized. The environmentally safe management of steel industry waste by-products and their valorization as secondary resources into value-added materials towards circular economy have attracted much attention in the last years. EAF Carbon steel slag in particular, is generated during the manufacture of carbon steel. It is a solid residue mainly composed of rich-in- Fe, Ca and Si compounds. The experimental results show that the beneficial incorporation of lower percentages of EAFC up to 6%wt. into ceramics sintered at 950 °C is attained without significant variations in sintering behavior and physico-mechanical properties. Further heating up to 1100 °C strongly enhances the densification of the ceramic microstructures, thus reducing the porosity and strengthening their mechanical performance. On the other side, in terms of thermal insulation behavior as well as energy consumption savings and production cost alleviation, the optimum sintering temperature appears to be 950 °C.

The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

NASA Astrophysics Data System (ADS)

Ivanov, Yuri; Tolkachev, Oleg; Petyukevich, Maria; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina; Polisadova, Valentina

2016-01-01

The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm2, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

Hardness and wear analysis of Cu/Al2O3 composite for application in EDM electrode

NASA Astrophysics Data System (ADS)

Hussain, M. Z.; Khan, U.; Jangid, R.; Khan, S.

2018-02-01

Ceramic materials, like Aluminium Oxide (Al2O3), have high mechanical strength, high wear resistance, high temperature resistance and good chemical durability. Powder metallurgy processing is an adaptable method commonly used to fabricate composites because it is a simple method of composite preparation and has high efficiency in dispersing fine ceramic particles. In this research copper and novel material aluminium oxide/copper (Al2O3/Cu) composite has been fabricated for the application of electrode in Electro-Discharge Machine (EDM) using powder metallurgy technique. Al2O3 particles with different weight percentages (0, 1%, 3% and 5%) were reinforced into copper matrix using powder metallurgy technique. The powders were blended and compacted at a load of 100MPa to produce green compacts and sintered at a temperature of 574 °C. The effect of aluminium oxide content on mass density, Rockwell hardness and wear behaviour were investigated. Wear behaviour of the composites was investigated on Die-Sink EDM (Electro-Discharge Machine). It was found that wear rate is highly depending on hardness, mass density and green protective carbonate layer formation at the surface of the composite.

Preliminary study on immobilization of buffing dust by solidification method in ceramic brick

NASA Astrophysics Data System (ADS)

Yuliansyah, Ahmad Tawfiequrrahman; Prasetya, Agus; Putra, Arif Eka; Satriawan, Humam Budi

2017-11-01

Leather-based industries generate a substantial amount of hazardous solid and liquid wastes in their process. One of the solid wastes is buffing dust, which is fine particulates containing fat, tanning, dyes and chromium. From 1 ton of leather processed, approximately 2-6 kg of buffing dust is generated. Chromium in the buffing dust is carcinogenic, so a proper handling is highly required. Solidification is a method commonly used to immobilize toxic material. Hence, the material is trapped in a matrix made of binding agents to minimize its mobility. However, a very small amount of the materials is sometimes released to the environment during storage. This study investigates leaching process of chromium from immobilized buffing dust in ceramic brick. Buffing dust, which contains chromium, is solidified by mixing it with clay at certain compositions and fired in a muffle furnace to produce a ceramic brick. Performance of the solidification process is evaluated by measuring the leaching of chromium in the leaching test. The results show that the solidification has significantly reduced the potential release of chromium to the environment. Higher of the firing temperature, less chromium is leached from ceramic brick. The chromium concentration of leachate water from 800°C brick is 0.376 ppm, while those from 850 and 900°C brick are 0.212 and 0.179 ppm respectively.

Sludge valorization from wastewater treatment plant to its application on the ceramic industry.

PubMed

Martínez-García, C; Eliche-Quesada, D; Pérez-Villarejo, L; Iglesias-Godino, F J; Corpas-Iglesias, F A

2012-03-01

The main aim of this study is to assess the effect of incorporating waste sludge on the properties and microstructure of clay used for bricks manufacturing. Wastewater treatment plants produce annually a great volume of sludge. Replacing clay in a ceramic body with different proportions of sludge can reduce the cost due to the utilization of waste and, at the same time, it can help to solve an environmental problem. Compositions were prepared with additions of 1%, 2.5%, 5%, 7.5%, 10% and 15% wt% waste sludge in body clay. In order to determine the technological properties, such as bulk density, linear shrinkage, water suction, water absorption and compressive strength, press-moulded bodies were fired at 950 °C for coherently bonding particles in order to enhance the strength and the other engineering properties of the compacted particles. Thermal heating destroys organic remainder and stabilizes inorganic materials and metals by incorporating oxides from the elemental constituent into a ceramic-like material. Results have shown that incorporating up to 5 wt% of sludge is beneficial for clay bricks. By contrast, the incorporation of sludge amounts over 5 wt% causes deterioration on the mechanical properties, therefore producing low-quality bricks. Copyright © 2011 Elsevier Ltd. All rights reserved.

Investigation of the stability of glass-ceramic composites containing CeTi 2 O 6 and CaZrTi 2 O 7 after ion implantation

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

Paknahad, Elham; Grosvenor, Andrew P.

Glass-ceramic composite materials have been investigated for nuclear waste sequestration applications due to their ability to incorporate large amounts of radioactive waste elements. A key property that needs to be understood when developing nuclear waste sequestration materials is how the structure of the material responds to radioactive decay of nuclear waste elements, which can be simulated by high energy ion implantation. Borosilicate glass-ceramic composites containing brannerite-type (CeTi2O6) or zirconolite-type (CaZrTi2O7) oxides were synthesized at different annealing temperatures and investigated after being implanted with high-energy Au ions to mimic radiation induced structural damage. Backscattered electron (BSE) images were collected to investigatemore » the interaction of the brannerite crystallites with the glass matrix before and after implantation and showed that the morphology of the crystallites in the composite materials were not affected by radiation damage. Surface sensitive Ti K-edge glancing angle XANES spectra collected from the implanted composite materials showed that the structures of the CeTi2O6 and CaZrTi2O7 ceramics were damaged as a result of implantation; however, analysis of Si L2,3-edge XANES spectra indicated that the glass matrix was not affected by ion implantation.« less

Investigation of the stability of glass-ceramic composites containing CeTi2O6 and CaZrTi2O7 after ion implantation

NASA Astrophysics Data System (ADS)

Paknahad, Elham; Grosvenor, Andrew P.

2017-12-01

Glass-ceramic composite materials have been investigated for nuclear waste sequestration applications due to their ability to incorporate large amounts of radioactive waste elements. A key property that needs to be understood when developing nuclear waste sequestration materials is how the structure of the material responds to radioactive decay of nuclear waste elements, which can be simulated by high energy ion implantation. Borosilicate glass-ceramic composites containing brannerite-type (CeTi2O6) or zirconolite-type (CaZrTi2O7) oxides were synthesized at different annealing temperatures and investigated after being implanted with high-energy Au ions to mimic radiation induced structural damage. Backscattered electron (BSE) images were collected to investigate the interaction of the brannerite crystallites with the glass matrix before and after implantation and showed that the morphology of the crystallites in the composite materials were not affected by radiation damage. Surface sensitive Ti K-edge glancing angle XANES spectra collected from the implanted composite materials showed that the structures of the CeTi2O6 and CaZrTi2O7 ceramics were damaged as a result of implantation; however, analysis of Si L2,3-edge XANES spectra indicated that the glass matrix was not affected by ion implantation.

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).

Grinding damage assessment on four high-strength ceramics.

PubMed

Canneto, Jean-Jacques; Cattani-Lorente, Maria; Durual, Stéphane; Wiskott, Anselm H W; Scherrer, Susanne S

2016-02-01

The purpose of this study was to assess surface and subsurface damage on 4 CAD-CAM high-strength ceramics after grinding with diamond disks of 75 μm, 54 μm and 18 μm and to estimate strength losses based on damage crack sizes. The materials tested were: 3Y-TZP (Lava), dense Al2O3 (In-Ceram AL), alumina glass-infiltrated (In-Ceram ALUMINA) and alumina-zirconia glass-infiltrated (In-Ceram ZIRCONIA). Rectangular specimens with 2 mirror polished orthogonal sides were bonded pairwise together prior to degrading the top polished surface with diamond disks of either 75 μm, 54 μm or 18 μm. The induced chip damage was evaluated on the bonded interface using SEM for chip depth measurements. Fracture mechanics were used to estimate fracture stresses based on average and maximum chip depths considering these as critical flaws subjected to tension and to calculate possible losses in strength compared to manufacturer's data. 3Y-TZP was hardly affected by grinding chip damage viewed on the bonded interface. Average chip depths were of 12.7±5.2 μm when grinding with 75 μm diamond inducing an estimated loss of 12% in strength compared to manufacturer's reported flexural strength values of 1100 MPa. Dense alumina showed elongated chip cracks and was suffering damage of an average chip depth of 48.2±16.3 μm after 75 μm grinding, representing an estimated loss in strength of 49%. Grinding with 54 μm was creating chips of 32.2±9.1 μm in average, representing a loss in strength of 23%. Alumina glass-infiltrated ceramic was exposed to chipping after 75 μm (mean chip size=62.4±19.3 μm) and 54 μm grinding (mean chip size=42.8±16.6 μm), with respectively 38% and 25% estimated loss in strength. Alumina-zirconia glass-infiltrated ceramic was mainly affected by 75 μm grinding damage with a chip average size of 56.8±15.1 μm, representing an estimated loss in strength of 34%. All four ceramics were not exposed to critical chipping at 18 μm diamond grinding. Reshaping a

Comparison of the load at fracture of Turkom-Cera to Procera AllCeram and In-Ceram all-ceramic restorations.

PubMed

AL-Makramani, Bandar M A; Razak, Abdul A A; Abu-Hassan, Mohamed I

2009-08-01

This study investigated the occlusal fracture resistance of Turkom-Cerafused alumina compared to Procera AllCeram and In-Ceram all-ceramic restorations. Sixmaster dies were duplicated from the prepared maxillary first premolar tooth using nonprecious metal alloy (Wiron 99). Ten copings of 0.6 mm thickness were fabricated from each type of ceramic, for a total of thirty copings. Two master dies were used for each group, and each of them was used to lute five copings. All groups were cemented with resin luting cement Panavia F according to manufacturer's instructions and received a static load of 5 kg during cementation. After 24 hours of distilled water storage at 37 degrees C, the copings were vertically compressed using a universal testing machine at a crosshead speed of 1 mm/min. The results of the present study showed the following mean loads at fracture: Turkom-Cera (2184 +/- 164 N), In-Ceram (2042 +/- 200 N), and Procera AllCeram (1954 +/- 211 N). ANOVA and Scheffe's post hoc test showed that the mean load at fracture of Turkom-Cera was significantly different from Procera AllCeram (p < 0.05). Scheffe's post hoc test showed no significant difference between the mean load at fracture of Turkom-Cera and In-Ceram or between the mean load at fracture of In-Ceram and Procera AllCeram. Because Turkom-Cera demonstrated equal to or higher loads at fracture than currently accepted all-ceramic materials, it would seem to be acceptable for fabrication of anterior and posterior ceramic crowns.

Use of a two-body belt abrasion test to measure the grindability of advanced ceramic materials

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

Blau, P.J.; Zanoria, E.S.

1998-07-01

Structural materials, such as superalloys, intermetallic alloys and engineering ceramics, have been developed to achieve high hardness, high temperature strength, and high fracture toughness. However, these strong materials also tend to be difficult to grind and finish. In the 1990's, the US Department of Energy supported a series of projects to help reduce the cost of machining advanced ceramics. The same properties that make engineering materials attractive for use on severe thermal and mechanical environments (e.g., high hardness, high temperature strength, high fracture toughness) generally tend to make those materials difficult to grind and finish. In the mid-1990's, a beltmore » abrasion test was developed under subcontract to Oak Ridge National Laboratory to help to assess the grindability of structural ceramic materials. The procedure involves applying a 10 N normal force to the end face of a 3 x 4 mm cross-section test bar for 30 seconds which is rubbed against a wet, 220 grit diamond belt moving at 10 m/s. By measuring the change in the bar length after at least six 30-second tests, a belt grindability index is computed and expressed using the same units as a traditional wear factor (i.e., mm{sup 3}/N-m). The test has shown an excellent capability to discriminate not only between ceramics of different basic compositions, e.g., Al{sub 2}O{sub 3}, SiC, and Si{sub 3}N{sub 4}, but also between different lots of the same basic ceramic. Test-to-test variability decreases if the belt is worn in on the material of interest. The surface roughness of the abraded ends of the test specimens does not correlate directly with the belt grindability index, but instead reflects another attribute of grindability; namely the ability of a material to abrade smoothly without leaving excessive rough and pitted areas.« less

Ceramic-ceramic shell tile thermal protection system and method thereof

NASA Technical Reports Server (NTRS)

Riccitiello, Salvatore R. (Inventor); Smith, Marnell (Inventor); Goldstein, Howard E. (Inventor); Zimmerman, Norman B. (Inventor)

1986-01-01

A ceramic reusable, externally applied composite thermal protection system (TPS) is proposed. The system functions by utilizing a ceramic/ceramic upper shell structure which effectively separates its primary functions as a thermal insulator and as a load carrier to transmit loads to the cold structure. The composite tile system also prevents impact damage to the atmospheric entry vehicle thermal protection system. The composite tile comprises a structurally strong upper ceramic/ceramic shell manufactured from ceramic fibers and ceramic matrix meeting the thermal and structural requirements of a tile used on a re-entry aerospace vehicle. In addition, a lightweight high temperature ceramic lower temperature base tile is used. The upper shell and lower tile are attached by means effective to withstand the extreme temperatures (3000 to 3200F) and stress conditions. The composite tile may include one or more layers of variable density rigid or flexible thermal insulation. The assembly of the overall tile is facilitated by two or more locking mechanisms on opposing sides of the overall tile assembly. The assembly may occur subsequent to the installation of the lower shell tile on the spacecraft structural skin.

Structural ceramics containing electric arc furnace dust.

PubMed

Stathopoulos, V N; Papandreou, A; Kanellopoulou, D; Stournaras, C J

2013-11-15

In the present work the stabilization of electric arc furnace dust EAFD waste in structural clay ceramics was investigated. EAFD was collected over eleven production days. The collected waste was characterized for its chemical composition by Flame Atomic Absorption Spectroscopy. By powder XRD the crystal structure was studied while the fineness of the material was determined by a laser particle size analyzer. The environmental characterization was carried out by testing the dust according to EN12457 standard. Zn, Pb and Cd were leaching from the sample in significant amounts. The objective of this study is to investigate the stabilization properties of EAFD/clay ceramic structures and the potential of EAFD utilization into structural ceramics production (blocks). Mixtures of clay with 2.5% and 5% EAFD content were studied by TG/DTA, XRD, SEM, EN12457 standard leaching and mechanical properties as a function of firing temperature at 850, 900 and 950 °C. All laboratory facilities maintained 20 ± 1 °C. Consequently, a pilot-scale experiment was conducted with an addition of 2.5% and 5% EAFD to the extrusion mixture for the production of blocks. During blocks manufacturing, the firing step reached 950 °C in a tunnel kiln. Laboratory heating/cooling gradients were similar to pilot scale production firing. The as produced blocks were then subjected to quality control tests, i.e. dimensions according to EN772-17, water absorbance according to EN772-6, and compressive strength according to EN772-1 standard, in laboratory facilities certified under EN17025. The data obtained showed that the incorporation of EAFD resulted in an increase of mechanical strength. Moreover, leaching tests performed according to the Europeans standards on the EAFD-block samples showed that the quantities of heavy metals leached from crushed blocks were within the regulatory limits. Thus the EAFD-blocks can be regarded as material of no environmental concern. Copyright © 2013 Elsevier B

Vitrification of copper flotation waste.

PubMed

Karamanov, Alexander; Aloisi, Mirko; Pelino, Mario

2007-02-09

The vitrification of an hazardous iron-rich waste (W), arising from slag flotation of copper production, was studied. Two glasses, containing 30wt% W were melted for 30min at 1400 degrees C. The first batch, labeled WSZ, was obtained by mixing W, blast furnace slag (S) and zeolite tuff (Z), whereas the second, labeled WG, was prepared by mixing W, glass cullet (G), sand and limestone. The glass frits showed high chemical durability, measured by the TCLP test. The crystallization of the glasses was evaluated by DTA. The crystal phases formed were identified by XRD resulting to be pyroxene and wollastonite solid solutions, magnetite and hematite. The morphology of the glass-ceramics was observed by optical and scanning electron microscopy. WSZ composition showed a high rate of bulk crystallization and resulted to be suitable for producing glass-ceramics by a short crystallization heat-treatment. WG composition showed a low crystallization rate and good sinterability; glass-ceramics were obtained by sinter-crystallization of the glass frit.

Integrally cored ceramic investment casting mold fabricated by ceramic stereolithography

NASA Astrophysics Data System (ADS)

Bae, Chang-Jun

Superalloy airfoils are produced by investment casting (IC), which uses ceramic cores and wax patterns with ceramic shell molds. Hollow cored superalloy airfoils in a gas turbine engine are an example of complex IC parts. The complex internal hollow cavities of the airfoil are designed to conduct cooling air through one or more passageways. These complex internal passageways have been fabricated by a lost wax process requiring several processing steps; core preparation, injection molding for wax pattern, and dipping process for ceramic shell molds. Several steps generate problems such as high cost and decreased accuracy of the ceramic mold. For example, costly tooling and production delay are required to produce mold dies for complex cores and wax patterns used in injection molding, resulting in a big obstacle for prototypes and smaller production runs. Rather than using separate cores, patterns, and shell molds, it would be advantageous to directly produce a mold that has the casting cavity and the ceramic core by one process. Ceramic stereolithography (CerSLA) can be used to directly fabricate the integrally cored ceramic casting mold (ICCM). CerSLA builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This dissertation addresses the integrally cored casting ceramic mold (ICCM), the ceramic core with a ceramic mold shell in a single patternless construction, fabricated by ceramic stereolithography (CerSLA). CerSLA is considered as an alternative method to replace lost wax processes, for small production runs or designs too complex for conventional cores and patterns. The main topic is the development of methods to successfully fabricate an ICCM by CerSLA from refractory silica, as well as related issues. The related issues are the segregation of coarse fused silica powders in a layer, the degree of segregation parameter to

Recycling of inorganic waste in monolithic and cellular glass‐based materials for structural and functional applications

PubMed Central

Rincón, Acacio; Marangoni, Mauro; Cetin, Suna

2016-01-01

Abstract The stabilization of inorganic waste of various nature and origin, in glasses, has been a key strategy for environmental protection for the last decades. When properly formulated, glasses may retain many inorganic contaminants permanently, but it must be acknowledged that some criticism remains, mainly concerning costs and energy use. As a consequence, the sustainability of vitrification largely relies on the conversion of waste glasses into new, usable and marketable glass‐based materials, in the form of monolithic and cellular glass‐ceramics. The effective conversion in turn depends on the simultaneous control of both starting materials and manufacturing processes. While silica‐rich waste favours the obtainment of glass, iron‐rich wastes affect the functionalities, influencing the porosity in cellular glass‐based materials as well as catalytic, magnetic, optical and electrical properties. Engineered formulations may lead to important reductions of processing times and temperatures, in the transformation of waste‐derived glasses into glass‐ceramics, or even bring interesting shortcuts. Direct sintering of wastes, combined with recycled glasses, as an example, has been proven as a valid low‐cost alternative for glass‐ceramic manufacturing, for wastes with limited hazardousness. The present paper is aimed at providing an up‐to‐date overview of the correlation between formulations, manufacturing technologies and properties of most recent waste‐derived, glass‐based materials. © 2016 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:27818564

An atomic-scale and high efficiency finishing method of zirconia ceramics by using magnetorheological finishing

NASA Astrophysics Data System (ADS)

Luo, Hu; Guo, Meijian; Yin, Shaohui; Chen, Fengjun; Huang, Shuai; Lu, Ange; Guo, Yuanfan

2018-06-01

Zirconia ceramics is a valuable crucial material for fabricating functional components applied in aerospace, biology, precision machinery, military industry and other fields. However, the properties of its high brittleness and high hardness could seriously reduce its finishing efficiency and surface quality by conventional processing technology. In this work, we present a high efficiency and high-quality finishing process by using magnetorheological finishing (MRF), which employs the permanent magnetic yoke with straight air gap as excitation unit. The sub-nanoscale surface roughness and damage free surface can be obtained after magnetorheological finishing. The XRD results and SEM morphologies confirmed that the mechanical shear removal with ductile modes are the dominant material removal mechanism for the magnetorheological finishing of zirconia ceramic. With the developed experimental apparatus, the effects of workpiece speed, trough speed and work gap on material removal rate and surface roughness were systematically investigated. Zirconia ceramics finished to ultra-smooth surface with surface roughness less than Ra 1 nm was repeatedly achieved during the parametric experiments. Additionally, the highest material removal rate exceeded 1 mg/min when using diamond as an abrasive particle. Magnetorheological finishing promises to be an adaptable and efficient method for zirconia ceramics finishing.

Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

PubMed Central

An, Jing; Song, Jinpeng; Liang, Guoxing; Gao, Jiaojiao; Xie, Juncai; Cao, Lei; Wang, Shiying; Lv, Ming

2017-01-01

The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure. PMID:28772821

Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

PubMed

Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

2010-01-01

This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

Tracking the Flow of Resources in Electronic Waste - The Case of End-of-Life Computer Hard Disk Drives.

PubMed

Habib, Komal; Parajuly, Keshav; Wenzel, Henrik

2015-10-20

Recovery of resources, in particular, metals, from waste flows is widely seen as a prioritized option to reduce their potential supply constraints in the future. The current waste electrical and electronic equipment (WEEE) treatment system is more focused on bulk metals, where the recycling rate of specialty metals, such as rare earths, is negligible compared to their increasing use in modern products, such as electronics. This study investigates the challenges in recovering these resources in the existing WEEE treatment system. It is illustrated by following the material flows of resources in a conventional WEEE treatment plant in Denmark. Computer hard disk drives (HDDs) containing neodymium-iron-boron (NdFeB) magnets were selected as the case product for this experiment. The resulting output fractions were tracked until their final treatment in order to estimate the recovery potential of rare earth elements (REEs) and other resources contained in HDDs. The results further show that out of the 244 kg of HDDs treated, 212 kg comprising mainly of aluminum and steel can be finally recovered from the metallurgic process. The results further demonstrate the complete loss of REEs in the existing shredding-based WEEE treatment processes. Dismantling and separate processing of NdFeB magnets from their end-use products can be a more preferred option over shredding. However, it remains a technological and logistic challenge for the existing system.

Structural Ceramics

NASA Technical Reports Server (NTRS)

1986-01-01

This publication is a compilation of abstracts and slides of papers presented at the NASA Lewis Structural Ceramics Workshop. Collectively, these papers depict the scope of NASA Lewis' structural ceramics program. The technical areas include monolithic SiC and Si3N4 development, ceramic matrix composites, tribology, design methodology, nondestructive evaluation (NDE), fracture mechanics, and corrosion.

Influence of Electrical Resistivity and Machining Parameters on Electrical Discharge Machining Performance of Engineering Ceramics

PubMed Central

Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

2014-01-01

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge

Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

PubMed

Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

2014-01-01

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge

Comparison of the metal-to-ceramic bond strengths of four noble alloys with press-on-metal and conventional porcelain layering techniques.

PubMed

Khmaj, Mofida R; Khmaj, Abdulfatah B; Brantley, William A; Johnston, William M; Dasgupta, Tridib

2014-11-01

New noble alloys for metal ceramic restorations introduced by manufacturers are generally lower-cost alternatives to traditional higher-gold alloys. Information about the metal-to-ceramic bond strength for these alloys, which is needed for rational clinical selection, is often lacking. The purpose of this study was to evaluate the bond strength of 4 recently introduced noble alloys by using 2 techniques for porcelain application. Aquarius Hard (high-gold: 86.1 gold, 8.5 platinum, 2.6 palladium, 1.4 indium; values in wt. %), Evolution Lite (reduced-gold: 40.3 gold, 39.3 palladium, 9.3 indium, 9.2 silver, 1.8 gallium), Callisto 75 Pd (palladium-silver containing gold: 75.2 palladium, 7.1 silver, 2.5 gold, 9.3 tin, 1.0 indium), and Aries, (conventional palladium-silver: 63.7 palladium, 26.0 silver, 7.0 tin, 1.8 gallium, 1.5 indium) were selected for bonding to leucite-containing veneering porcelains. Ten metal ceramic specimens that met dimensional requirements for International Organization for Standardization (ISO) Standard 9693 were prepared for each alloy by using conventional porcelain layering and press-on-metal methods. The 3-point bending test in ISO Standard 9693 was used to determine bond strength. Values were compared with 2-way ANOVA (maximum likelihood analysis, SAS Mixed Procedure) and the Tukey test (α=.05). Means (standard deviations) for bond strength with conventional porcelain layering were as follows: Aquarius Hard (50.7 ±5.5 MPa), Evolution Lite (40.2 ±3.3 MPa), Callisto 75 Pd (37.2 ±3.9 MPa), and Aries (34.0 ±4.9 MPa). For the press-on-metal technique, bond strength results were as follows: Aquarius Hard (33.7 ±11.5 MPa), Evolution Lite (34.9 ±4.5 MPa), Callisto 75 Pd (37.2 ±11.9 MPa), and Aries (30.7 ±10.8 MPa). From statistical analyses, the following 3 significant differences were found for metal-to-ceramic bond strength: the bond strength for Aquarius Hard was significantly higher for conventional porcelain layers compared with

Ceramic-glass-ceramic seal by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1983-10-04

A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

Ceramic-glass-ceramic seal by microwave heating

DOEpatents

Meek, Thomas T.; Blake, Rodger D.

1985-01-01

A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

Detoxification and immobilization of chromite ore processing residue in spinel-based glass-ceramic.

PubMed

Liao, Chang-Zhong; Tang, Yuanyuan; Lee, Po-Heng; Liu, Chengshuai; Shih, Kaimin; Li, Fangbai

2017-01-05

A promising strategy for the detoxification and immobilization of chromite ore processing residue (COPR) in a spinel-based glass-ceramic matrix is reported in this study. In the search for a more chemically durable matrix for COPR, the most critical crystalline phase for Cr immobilization was found to be a spinel solid solution with a chemical composition of MgCr 1.32 Fe 0.19 Al 0.49 O 4 . Using Rietveld quantitative X-ray diffraction analysis, we identified this final product is with the phases of spinel (3.5wt.%), diopside (5.2wt.%), and some amorphous contents (91.2wt.%). The partitioning ratio of Cr reveals that about 77% of the Cr was incorporated into the more chemically durable spinel phase. The results of Cr K-edge X-ray absorption near-edge spectroscopy show that no Cr(VI) was observed after conversion of COPR into a glass-ceramic, which indicates successful detoxification of Cr(VI) into Cr(III) in the COPR-incorporated glass-ceramic. The leaching performances of Cr 2 O 3 and COPR-incorporated glass-ceramic were compared with a prolonged acid-leaching test, and the results demonstrate the superiority of the COPR-incorporated glass-ceramic matrix in the immobilization of Cr. The overall results suggest that the use of affordable additives has potential in more reliably immobilizing COPR with a spinel-based glass-ceramic for safer disposal of this hazardous waste. Copyright © 2016 Elsevier B.V. All rights reserved.

CoO-doped MgO-Al2O3-SiO2-colored transparent glass-ceramics with high crystallinity

NASA Astrophysics Data System (ADS)

Tang, Wufu; Zhang, Qian; Luo, Zhiwei; Yu, Jingbo; Gao, Xianglong; Li, Yunxing; Lu, Anxian

2018-02-01

To obtain CoO-doped MgO-Al2O3-SiO2 (MAS)-colored transparent glass-ceramics with high crystallinity, the glass with the composition 21MgO-21Al2O3-54SiO2-4B2O3-0.2CoO (in mol %) was prepared by conventional melt quenching technique and subsequently thermal treated at several temperatures. The crystallization behavior of the glass, the precipitated crystalline phases and crystallinity were analyzed by X-ray diffraction (XRD). The microstructure of the glass-ceramics was characterized by field emission scanning electron microscopy (FSEM). The transmittance of glass-ceramic was measured by UV spectrophotometer. The results show that a large amount of α-cordierite (indianite) with nano-size was precipitated from the glass matrix after treatment at 1020 °C for 3 h. The crystallinity of the transparent glass-ceramic reached up to 97%. Meanwhile, the transmittance of the glass-ceramic was 74% at 400 nm with a complex absorption band from 450 nm to 700 nm. In addition, this colored transparent glass-ceramic possessed lower density (2.469 g/cm3), lower thermal expansion coefficient (1.822 × 10-6 /℃), higher Vickers hardness (9.1 GPa) and higher bending strength (198 MPa) than parent glass.

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.

Randomized, Controlled Clinical Trial of Bilayer Ceramic and Metal-Ceramic Crown Performance

PubMed Central

Esquivel-Upshaw, Josephine; Rose, William; Oliveira, Erica; Yang, Mark; Clark, Arthur E.; Anusavice, Kenneth

2013-01-01

Purpose Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher’s exact test. Results There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns

Adjusting dental ceramics: An in vitro evaluation of the ability of various ceramic polishing kits to mimic glazed dental ceramic surface.

PubMed

Steiner, René; Beier, Ulrike S; Heiss-Kisielewsky, Irene; Engelmeier, Robert; Dumfahrt, Herbert; Dhima, Matilda

2015-06-01

During the insertion appointment, the practitioner is often faced with the need to adjust ceramic surfaces to fit a restoration to the adjacent or opposing dentition and soft tissues. The purpose of this study was to assess the ceramic surface smoothness achieved with various commercially available ceramic polishing kits on different commonly used ceramic systems. The reliability of the cost of a polishing kit as an indicator of improved surface smoothness was assessed. A total of 350 ceramic surfaces representing 5 commonly available ceramic systems (IPS Empress Esthetic, IPS e.max Press, Cergo Kiss, Vita PM 9, Imagine PressX) were treated with 5 types of ceramic polishing systems (Cerapreshine, 94006C, Ceramiste, Optrafine, Zenostar) by following the manufacturers' guidelines. The surface roughness was measured with a profilometer (Taylor Hobson; Precision Taylor Hobson Ltd). The effects of ceramic systems and polishing kits of interest on surface roughness were analyzed by 2-way ANOVA, paired t test, and Bonferroni corrected significance level. The ceramic systems and polishing kits statistically affected surface roughness (P<.001).The polishing kit Zenostar on IPS e.max Press created the smoothest ceramic surface. No correlation could be established between the high cost of the polishing kit and low surface roughness. None of the commonly used ceramic polishing kits could create a surface smoother than that of glazed ceramic (P<.001). The inclusion of a diamond polishing paste step is recommended to improve surface smoothness (P<.001). The cost of ceramic polishing kits is not recommended as a reliable indicator of better performance of ceramic polishing kits (P>.30). Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Novel resorbable glass-ceramic scaffolds for hard tissue engineering: from the parent phosphate glass to its bone-like macroporous derivatives.

PubMed

Bretcanu, Oana; Baino, Francesco; Verné, Enrica; Vitale-Brovarone, Chiara

2014-05-01

One of the major challenges of hard tissue engineering research focuses on the development of scaffolds that can match the mechanical properties of the host bone and resorb at the same rate as the bone is repaired. The aim of this work was the synthesis and characterization of a resorbable phosphate glass, as well as its application for the fabrication of three dimensional (3-D) scaffolds for bone regeneration. The glass microstructure and behaviour upon heating were analysed by X-ray diffraction, differential scanning calorimetry and hot stage microscopy. The glass solubility was investigated according to relevant ISO standards using distilled water, simulated body fluid (SBF) and Tris-HCl as testing media. The glass underwent progressive dissolution over time in all three media but the formation of a hydroxyapatite-like layer was also observed on the samples soaked in SBF and Tris-HCl, which demonstrated the bioactivity of the material. The glass powder was used to fabricate 3-D macroporous bone-like glass-ceramic scaffolds by adopting polyethylene particles as pore formers: during thermal treatment, the polymer additive was removed and the sintering of glass particles was allowed. The obtained scaffolds exhibited high porosity (87 vol.%) and compressive strength around 1.5 MPa. After soaking for 4 months in SBF, the scaffolds mass loss was 76 wt.% and the pH of the solution did not exceed the 7.55 value, thereby remaining in a physiological range. The produced scaffolds, being resorbable, bioactive, architecturally similar to trabecular bone and exhibiting interesting mechanical properties, can be proposed as promising candidates for bone repair applications.

Alumina-based ceramic composite

DOEpatents

Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

1996-01-01

An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite.

Physico-mechanical properties of resin cement light cured through different ceramic spacers.

PubMed

Rizzante, Fabio Antonio Piola; Locatelli, Paula Minatel; Porto, Thiago Soares; Borges, Ana Flávia Sanches; Mondelli, Rafael Francisco Lia; Ishikiriama, Sérgio Kiyoshi

2018-06-04

The purpose of this in vitro study was to compare the micro hardness, color stability/ΔE, and degree of conversion/DC of a resin cement light cured through different ceramic spacers. Lithium-disilicate ceramic samples were obtained from IPS E-max CAD blocks (HT A1) and IPS in-Ceram (transparent neutral); and divided in 7 groups (n = 8 for each test): CTR/control group; 06 M/0.6 mm monolithic; 12 M/1.2 mm monolithic; 20 M/2.0 mm monolithic; 06B/0.4 + 0.2 mm bilayered; 12B/1.0 + 0.2 mm bilayered; 20B/1.8 + 0.2 mm bilayered. The resin cement (Variolink veneer) was light cured through the ceramic spacers. The resin cement samples were evaluated for ΔE using a spectrophotometer after 24 h, 7days and after aging (24 h in water at 60 °C). Knoop microhardness and DC tests were conducted immediately after light curing, after 24 h and 7days. All experimental groups showed similar microhardness values, although being lower than CTR group. Similar results were observed after 7days. ΔE was similar between all groups after 24 h (except for 12B and 20B), and increased for all groups after 7days and after artificial aging, especially for thicker and bilayer groups. Only 06 M showed values similar to CTR group. DC values were similar to all groups immediately after light curing, increasing after 24 h and 7days. After 7days, only group 20B showed lower DC than CTR group. A tendency of higher DC could be observed for monolithic and thinner ceramics. All test results showed strong correlation (0.9987). Ceramic interposition can reduce mechanical and physical properties of resin cements, especially with thicker and bilayered ceramics. Group 06 M showed the best ΔE overtime. Published by Elsevier Ltd.

Remedial processing of oil shale fly ash (OSFA) and its value-added conversion into glass-ceramics.

PubMed

Zhang, Zhikun; Zhang, Lei; Li, Aimin

2015-12-01

Recently, various solid wastes such as sewage sludge, coal fly ash and slag have been recycled into various products such as sintered bricks, ceramics and cement concrete. Application of these recycling approaches is much better and greener than conventional landfills since it can solve the problems of storage of industrial wastes and reduce exploration of natural resources for construction materials to protect the environment. Therefore, in this study, an attempt was made to recycle oil shale fly ash (OSFA), a by-product obtained from the extracting of shale oil in the oil shale industry, into a value-added glass-ceramic material via melting and sintering method. The influence of basicity (CaO/SiO2 ratio) by adding calcium oxide on the performance of glass-ceramics was studied in terms of phase transformation, mechanical properties, chemical resistances and heavy metals leaching tests. Crystallization kinetics results showed that the increase of basicity reduced the activation energies of crystallization but did not change the crystallization mechanism. When increasing the basicity from 0.2 to 0.5, the densification of sintering body was enhanced due to the promotion of viscous flow of glass powders, and therefore the compression strength and bending strength of glass-ceramics were increased. Heavy metals leaching results indicated that the produced OSFA-based glass-ceramics could be taken as non-hazardous materials. The maximum mechanical properties of compression strength of 186 ± 3 MPa, bending strength of 78 ± 6 MPa, good chemical resistances and low heavy metals leaching concentrations showed that it could be used as a substitute material for construction applications. The proposed approach will be one of the potential sustainable solutions in reducing the storage of oil shale fly ash as well as converting it into a value-added product. Copyright © 2015 Elsevier Ltd. All rights reserved.

Titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition and a process for making the same

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.

1991-01-01

A ceramic composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to about 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness.

New advanced surface modification technique: titanium oxide ceramic surface implants: long-term clinical results

NASA Astrophysics Data System (ADS)

Szabo, Gyorgy; Kovacs, Lajos; Barabas, Jozsef; Nemeth, Zsolt; Maironna, Carlo

2001-11-01

The purpose of this paper is to discuss the background to advanced surface modification technologies and to present a new technique, involving the formation of a titanium oxide ceramic coating, with relatively long-term results of its clinical utilization. Three general techniques are used to modify surfaces: the addition or removal of material and the change of material already present. Surface properties can also be changed without the addition or removal of material, through the laser or electron beam thermal treatment. The new technique outlined in this paper relates to the production of a corrosion-resistant 2000-2500 A thick, ceramic oxide layer with a coherent crystalline structure on the surface of titanium implants. The layer is grown electrochemically from the bulk of the metal and is modified by heat treatment. Such oxide ceramic-coated implants have a number of advantageous properties relative to implants covered with various other coatings: a higher external hardness, a greater force of adherence between the titanium and the oxide ceramic coating, a virtually perfect insulation between the organism and the metal (no possibility of metal allergy), etc. The coated implants were subjected to various physical, chemical, electronmicroscopic, etc. tests for a qualitative characterization. Finally, these implants (plates, screws for maxillofacial osteosynthesis and dental root implants) were applied in surgical practice for a period of 10 years. Tests and the experience acquired demonstrated the good properties of the titanium oxide ceramic-coated implants.

Nuclear Waste Disposal and Strategies for Predicting Long-Term Performance of Material

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

Wicks, G G

2001-03-28

Ceramics have been an important part of the nuclear community for many years. On December 2, 1942, an historic event occurred under the West Stands of Stagg Field, at the University of Chicago. Man initiated his first self-sustaining nuclear chain reaction and controlled it. The impact of this event on civilization is considered by many as monumental and compared by some to other significant events in history, such as the invention of the steam engine and the manufacturing of the first automobile. Making this event possible and the successful operation of this first man-made nuclear reactor, was the use ofmore » forty tons of UO2. The use of natural or enriched UO2 is still used today as a nuclear fuel in many nuclear power plants operating world-wide. Other ceramic materials, such as 238Pu, are used for other important purposes, such as ceramic fuels for space exploration to provide electrical power to operate instruments on board spacecrafts. Radioisotopic Thermoelectric Generators (RTGs) are used to supply electrical power and consist of a nuclear heat source and converter to transform heat energy from radioactive decay into electrical power, thus providing reliable and relatively uniform power over the very long lifetime of a mission. These sources have been used in the Galileo spacecraft orbiting Jupiter and for scientific investigations of Saturn with the Cassini spacecraft. Still another very important series of applications using the unique properties of ceramics in the nuclear field, are as immobilization matrices for management of some of the most hazardous wastes known to man. For example, in long-term management of radioactive and hazardous wastes, glass matrices are currently in production immobilizing high-level radioactive materials, and cementious forms have also been produced to incorporate low level wastes. Also, as part of nuclear disarmament activities, assemblages of crystalline phases are being developed for immobilizing weapons grade

Alumina-based ceramic composite

DOEpatents

Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

1996-07-23

An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite. 5 figs.

Evaluation of Vickers hardness and depth of cure of six composite resins photo-activated with different polymerization modes.

PubMed

Poggio, C; Lombardini, M; Gaviati, S; Chiesa, M

2012-07-01

The current in vitro study evaluated Vickers hardness (VK) and depth of cure (hardness ratio) of six resin composites, polymerized with a light-emitting diode (LED) curing unit by different polymerization modes: Standard 20 s, Standard 40 s, Soft-start 40 s. SIX RESIN COMPOSITES WERE SELECTED FOR THE PRESENT STUDY: three microhybrid (Esthet.X HD, Amaris, Filtek Silorane), two nanohybrid (Grandio, Ceram.X mono) and one nanofilled (Filtek Supreme XT). The VK of the surface was determined with a microhardness tester using a Vickers diamond indenter and a 200 g load applied for 15 seconds. The mean VK and hardness ratio of the specimens were calculated using the formula: hardness ratio = VK of bottom surface / VK of top surface. For all the materials tested and with all the polymerization modes, hardness ratio was higher than the minimum value indicated in literature in order to consider the bottom surface as adequately cured (0.80). Curing time did not affect hardness ratio values for Filtek Silorane, Grandio and Filtek Supreme XT. The effectiveness of cure at the top and bottom surface was not affected by Soft-start polymerization mode.

Finite element analysis of ion transport in solid state nuclear waste form materials

NASA Astrophysics Data System (ADS)

Rabbi, F.; Brinkman, K.; Amoroso, J.; Reifsnider, K.

2017-09-01

Release of nuclear species from spent fuel ceramic waste form storage depends on the individual constituent properties as well as their internal morphology, heterogeneity and boundary conditions. Predicting the release rate is essential for designing a ceramic waste form, which is capable of effectively storing the spent fuel without contaminating the surrounding environment for a longer period of time. To predict the release rate, in the present work a conformal finite element model is developed based on the Nernst Planck Equation. The equation describes charged species transport through different media by convection, diffusion, or migration. And the transport can be driven by chemical/electrical potentials or velocity fields. The model calculates species flux in the waste form with different diffusion coefficient for each species in each constituent phase. In the work reported, a 2D approach is taken to investigate the contributions of different basic parameters in a waste form design, i.e., volume fraction, phase dispersion, phase surface area variation, phase diffusion co-efficient, boundary concentration etc. The analytical approach with preliminary results is discussed. The method is postulated to be a foundation for conformal analysis based design of heterogeneous waste form materials.

Tribology of ceramics: Report of the Committee on Tribology of Ceramics

NASA Technical Reports Server (NTRS)

1988-01-01

The current state of knowledge of ceramic surface structures, composition, and reactivity is reviewed. The tribological requirements of advanced mechanical systems now being deployed (in particular, heat engines) exceed the capabilities of traditional metallic-based materials because of the high temperatures encountered. Advanced ceramic materials for such applications are receiving intense scrutiny, but there is a lack of understanding of the properties and behavior of ceramic surfaces and the influence of processing on the properties of ceramics is described. The adequacy of models, ranging form atomic to macro, to describe and to predict ceramic friction and wear are discussed, as well as what is known about lubrication at elevated temperatures. From this analysis, recommendations are made for coordination, research, and development that will lead to better performance of ceramic materials in tribological systems.

Gneiss wastes as secondary raw material for the ceramic industry: an example from the Verbano Cusio Ossola district (Piedmont, north-western Alps, Italy)

NASA Astrophysics Data System (ADS)

Cavallo, Alessandro

2015-04-01

The Verbano Cusio Ossola province (VCO, Piedmont, north-western Italy) is one of the most important Italian quarrying districts, due to the peculiarity and variety of its exploited rock types, mainly orthogneisses such as Serizzo and Beola, and subordinately granites, marbles and other rocks. The most important and extensively exploited ornamental stone from the VCO province is surely the Serizzo, commercialized in four main varieties, and representing about 70% of all the stone production from the VCO area. The protholith of the Serizzo is a Permian granite - granodiorite metamorphosed during the alpine events, and the rock-forming minerals are mainly quartz, K-feldspar, plagioclase (andesine), biotite, with variable amounts of muscovite and epidote (allanite). The other important ornamental stone of the VCO province is the Beola, a series of heterogeneous materials (mainly orthogneisses) with marked (mylonitic) foliation and strong mineralogical lineation, occurring in the median Ossola Valley; its production (15% of the whole stones of the VCO) is subordinated with respect to that of Serizzo. The mineralogical composition of the Beola varieties is similar to Serizzo, consisting of quite homogeneous quartz, K-feldspar (orthoclase or microcline), plagioclase, biotite and muscovite. The main differences relate to the grain size, the rock fabric (generally mylonitic) and to the presence of accessory/secondary minerals. Recent regulatory developments and the growing environmental awareness, require an increasing reuse of wastes deriving from the extraction and processing of dimension stones (up to 50 % of the extracted gross volume). Granite wastes from the VCO (Baveno pink granite and Montorfano white granite), after specific industrial treatments (crushing, sieving, drying, magnetic separation of biotite and hornblende), are used successfully as quartz-feldspars mix in the ceramic industry, with very low FeOtot content. On the other hand, other quartzose

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.

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.

Filtration performance of microporous ceramic supports.

PubMed

Belouatek, Aissa; Ouagued, Abdellah; Belhakem, Mustapha; Addou, Ahmed

2008-04-24

The use of inorganic membranes in pollution treatment is actually limited by the cost of such membranes. Advantages of inorganic membranes are their chemical, thermal and pH properties. The purpose of this work was the development of microporous ceramic materials based on clay for liquid waste processing. The supports or ceramic filters having various compositions were prepared and thermally treated at 1100 degrees C. The results show that, at the temperature studied, porosity varied according to the support composition from 12% for the double-layered (ceramic) support to 47% for the activated carbon- filled support with a mean pore diameter between 0.8 and 1.3 microm, respectively. Volumes of 5 l of distilled water were filtered tangentially for 3 h under an applied pressure of 3.5 and 5.5 bar. The retention of tubular supports prepared was tested with molecules of varying size (Evans blue, NaCl and Sacharose). The study of the liquid filtration and flow through these supports showed that the retention rate depends on support composition and pore diameter, and solute molecular weight. The S1 support (mixture of barbotine and 1% (w/w) activated carbon) gave a flux for distilled water of 68 L/m2 h while the double-layered support resulted in a flux of 8 L/m2 h for the same solution at the pressure of 3.5 bar. At a pressure of 5.5 bar an increase in the distilled water flux through the various supports was observed. It was significant for the S1 support (230 L/m h).

Preparation and Characterization of a Calcium Phosphate Ceramic for the Immobilization of Chloride-containing Intermediate Level Waste

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

Metcalfe, Brian; Donald, Ian W.; Scheele, Randall D.

2003-12-01

Attention has recently been given to the immobilization of special categories of radioactive wastes, some of which contain high concentrations of actinide chlorides. Although vitrification in phosphate glass has been proposed, this was rejected because of the high losses of chloride. On the basis of non-radioactive and, more recently, radioactive studies, we have shown that calcium phosphate is an effective host for immobilizing the chloride constituents [1]. In this instance, the chlorine is retained as chloride, rather than evolved as a chlorine-bearing gas. The immobilized product is in the form of a free-flowing, non-hygroscopic powder, in which the chlorides aremore » chemically combined within the mineral phases chlorapatite [Ca5(PO4)3Cl] and spodiosite [Ca2(PO4)Cl]. Data from studies on non-radioactive simulated waste consisting of a mixture of CaCl2 and SmCl3, and radioactive simulated waste composed of CaCl2 with PuCl3 or PuCl3 and AmCl3, are presented and compared. The XRD data confirm the presence of chlorapatite and spodiosite in the non-radioactive and radioactive materials. The durability of all specimens was measured with a modified MCC-1 test. Releases of Cl after 28 days were 1.6 x 10-3 g m-2 for the non-radioactive specimens and 7 x 10-3 g m-2 for the Pu-bearing specimens. Releases of Ca after 28 days were 0.3 x 10-3 and 2.0 x 10-3 g m-2 for the non-radioactive composition and the Pu composition, respectively, whilst release of Pu from the radioactive specimens was lower for the mixed Pu/Am specimen at 1.2 x 10-5g m-2. The release of Am from the mixed Pu/Am composition was exceptionally low at 2.4 x 10-7 g m-2. Overall, the release rate data suggest that the ceramics dissolve congruently, followed by precipitation of Sm, Pu and Am as less soluble phases, possibly oxides or phosphates. The differences in behaviour noted between non-radioactive and radioactive specimens are interpreted in terms of the crystal chemistry of the individual systems.« less

Ti1-xAux Alloys: Hard Biocompatible Metals and Their Possible Applications

NASA Astrophysics Data System (ADS)

Svanidze, Eteri; Besara, Tiglet; Ozaydin, M. Fevzi; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Morosan, Emilia

2015-03-01

The search for new hard materials is often challenging from both theoretical and experimental points of view. Furthermore, using materials for biomedical applications calls for alloys with high biocompatibility which are even more sparse. The Ti1-xAux (0 . 22 <= x <= 0 . 8) exhibit extreme hardness and strength values, elevated melting temperatures (compared to those of constituent elements), reduced density compared to Au, high malleability, bulk metallicity, high biocompatibility, low wear, reduced friction, potentially high radio opacity, as well as osseointegration. All these properties render the Ti1-xAux alloys particularly useful for orthopedic, dental, and prosthetic applications, where they could be used as both permanent and temporary components. Additionally, the ability of Ti1-xAux alloys to adhere to ceramic parts could reduce the weight and cost of these components. The work at Rice was supported by NSF DMR 0847681 (E.M. and E.S.).

Preparation and mechanical properties of carbon nanotube-silicon nitride nano-ceramic matrix composites

NASA Astrophysics Data System (ADS)

Tian, C. Y.; Jiang, H.

2018-01-01

Carbon nanotube-silicon nitride nano-ceramic matrix composites were fabricated by hot-pressing nano-sized Si3N4 powders and carbon nanotubes. The effect of CNTs on the mechanical properties of silicon nitride was researched. The phase compositions and the microstructure characteristics of the samples as well as the distribution of carbon nanotube in the silicon nitride ceramic were analyzed by X-ray diffraction and scanning electron microscope. The results show that the microstructure of composites consists mainly of α-Si3N4, β-Si3N4, Si2N2O and carbon natubes. The addition of proper amount of carbon nanotubes can improve the fracture toughness and the flexural strength, and the optimal amount of carbon nanotube are both 3wt.%. However the Vickers hardness values decrease with the increase of carbon nanotubes content.

Glass-ceramics from municipal incinerator fly ash

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

Boccaccini, A.R.; Petitmermet, M.; Wintermantel, E.

1997-11-01

In countries where the population density is high and the availability of space for landfilling is limited, such as the west-European countries and Japan, the significance of municipal solid waste incineration, as part of the waste management strategy, is continuously increasing. In Germany and Switzerland, for example, more than {approximately}40% of unrecycled waste is being or will be incinerated. Also, in other countries, including the US, the importance of waste incineration will increase in the next few years. Although incineration reduces the volume of the waste by {approximately} 90%, it leaves considerable amounts of solid residues, such as bottom andmore » boiler ashes, and filter fly ashes. Consequently, new technological options for the decontamination and/or inertization of incinerator filter fly ash are being developed with the objective of rendering a product that can be reused or, at least, be deposited in standard landfill sites with no risk. The proposed alternatives include immobilization by cement-based techniques, wet chemical treatments and thermal treatments of vitrification. Of these, vitrification is the most promising solution, because, if residues are melted at temperatures > 1,300 C, a relatively inert glass is produced. In the present investigation, glass-ceramics were obtained by a controlled crystallization heat treatment of vitrified incinerator filter fly ashes. The mechanical and other technical properties of the products were measured with special emphasis on assessing their in vitro toxic potential.« less

Machinability of lithium disilicate glass ceramic in in vitro dental diamond bur adjusting process.

PubMed

Song, Xiao-Fei; Ren, Hai-Tao; Yin, Ling

2016-01-01

Esthetic high-strength lithium disilicate glass ceramics (LDGC) are used for monolithic crowns and bridges produced in dental CAD/CAM and oral adjusting processes, which machinability affects the restorative quality. A machinability study has been made in the simulated oral clinical machining of LDGC with a dental handpiece and diamond burs, regarding the diamond tool wear and chip control, machining forces and energy, surface finish and integrity. Machining forces, speeds and energy in in vitro dental adjusting of LDGC were measured by a high-speed data acquisition and force sensor system. Machined LDGC surfaces were assessed using three-dimensional non-contact chromatic confocal optical profilometry and scanning electron microscopy (SEM). Diamond bur morphology and LDGC chip shapes were also examined using SEM. Minimum tool wear but significant LDGC chip accumulations were found. Machining forces and energy significantly depended on machining conditions (p<0.05) and were significantly higher than other glass ceramics (p<0.05). Machining speeds dropped more rapidly with increased removal rates than other glass ceramics (p<0.05). Two material machinability indices associated with the hardness, Young's modulus and fracture toughness were derived based on the normal force-removal rate relations, which ranked LDGC the most difficult to machine among glass ceramics. Surface roughness for machined LDGC was comparable for other glass ceramics. The removal mechanisms of LDGC were dominated by penetration-induced brittle fracture and shear-induced plastic deformation. Unlike most other glass ceramics, distinct intergranular and transgranular fractures of lithium disilicate crystals were found in LDGC. This research provides the fundamental data for dental clinicians on the machinability of LDGC in intraoral adjustments. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Influence on mechanical properties and microstructure of nano-zirconia toughened alumina ceramics with nano-zirconia content].

PubMed

Wang, Guang-Kui; Kang, Hong; Bao, Guang-Jie; Lv, Jin-Jun; Gao, Fei

2006-10-01

To investigate the mechanical properties and microstructure of nano -zirconia toughened alumina ceramics with variety of nano-zirconia content in centrifugal infiltrate casting processing of dental all-ceramic. Composite powder with different ethanol-water ratio, obtained serosity from ball milling and centrifugal infiltrate cast processing of green, then sintered at 1 450 degrees C for 8 h. The physical and mechanical properties of the sintered sample after milling and polishing were tested. Microstructures of the surface and fracture of the sintered sample were investigated by SEM. The experimental results showed that there had statistical significience (P < 0.01) on static three-point flexure strength and Vickers Hardness in three kinds of different nano-zirconia content sintered sample. Fracture toughness of 20% group was different from other two groups, while 10% group had not difference from 30% group (P < 0.05). The mechanical properties of this ceramic with 20% nano-zirconia was the best of the three, the static three-point flexure strength was (433 +/- 19) MPa and fracture toughness was (7.50 +/- 0.56) MPa x min 1/2. The intra/inter structure, fracture of intragranular and intergranular on the surface and fracture of sintered sample in microstrucre was also found. Intra/inter structure has strengthen toughness in ceramics. It has better toughness with 20% nano-zirconia, is suitable dental all-ceramic restoratives.

Environment-Conscious Ceramics (Ecoceramics) Technology Received 2001 R&D 100 Award

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay

2002-01-01

Since the dawn of human civilization, there has been a delicate balance between the use of resources as human frontiers expanded and the need to have a minimum influence on the ecosystem. The first 200 years of the industrial revolution essentially solved the problem of production. However, the massive production of goods also generated tremendous amounts of byproducts and wastes. In the new millennium, to sustain a healthy life in harmony with nature, it will be extremely important for us to develop various materials, products, and processes that minimize any harmful influence on the environment. Environment-conscious ceramics (ecoceramics) are a new class of materials that can be fabricated with renewable resources (wood) and wood waste material (wood sawdust). Wood is a "lignocellulosic" material formed by the photosynthetic reaction within the needles or leaves of trees. The photosynthesis process uses sunlight to take carbon dioxide from air and convert it into oxygen and organic materials. Wood has been known to be one of the best and most intricate engineering materials created by nature and known to mankind. In addition, natural woods of various types are available throughout the world. On the other hand, wood sawdusts are generated in abundant quantities by sawmills. Environment-conscious ceramic materials, fabricated via the pyrolysis and infiltration of natural wood-derived preforms, have tailorable properties with numerous potential applications. The experimental studies conducted to date on the development of materials based on biologically derived structures indicate that these materials behave like ceramic materials manufactured by conventional approaches. These structures have been shown to be quite useful in producing porous or dense materials having various microstructures and compositions.

A study on the performance of concrete containing recycled aggregates and ceramic as materials replacement

NASA Astrophysics Data System (ADS)

Azmi, N. B.; Khalid, F. S.; Irwan, J. M.; Anting, N.; Mazenan, P. N.

2017-11-01

Natural fine aggregate materials are commonly used in development and commercial construction in Malaysia. In fact, concrete production was increased as linear with the growing Malaysia economy. However, an issue was production of concrete was to locate adequate sources of natural fine aggregates. There lot of studies have been conducted in order to replace the fine aggregate in which natural fine aggregate replace with the waste material in concrete preparation. Therefore, this study aims to utilize the Recycled Concrete Aggregate (RCA) and ceramic waste which has great potential to replace the natural aggregate in concrete mix with different type of method, admixture, and parameters. This research were focused on compressive strength and water absorption test to determine the optimum mix ratio of concrete mix. The concrete aggregate was chosen due to improvement capillary bonding mechanisms and ceramic presented similar strength compared to the conventional concrete using natural aggregate. Percent of replacement have been used in this study was at 25%, 35% and 45% of the RCA and 5%, 10% and 15% for ceramic, respectively. Furthermore, this research was conduct to find the optimum percentage of aggregate replacement, using water-cement ratio of 0.55 with concrete grade 25/30. The best percentage of replacement was the RCA35% C15% with the compressive strength of 34.72 MPa and the water absorption was satisfied.

Properties of Miniature Cantilever-Type Ultrasonic Motor Using Lead-Free Array-Type Multilayer Piezoelectric Ceramics of (Sr,Ca)2NaNb5O15 under High Input Power

NASA Astrophysics Data System (ADS)

Doshida, Yutaka; Shimizu, Hiroyuki; Mizuno, Youich; Tamura, Hideki

2012-07-01

The properties of miniature cantilever-type ultrasonic motors using lead-free array-type multilayer piezoelectric ceramics of (Sr,Ca)2NaNb5O15 (SCNN) developed using the design rule were investigated under high input power by comparison with the high-power properties of SCNN ceramics. The frequency dependence of the revolution speed reflected the nonlinear behavior of SCNN ceramics with the hard-spring effect and showed a mirror-reversed image relative to that of the motor of Pb(Zr,Ti)O3 (PZT) ceramics. The output power increased linearly with increasing input power up to 110 mW without heat generation, and the driving properties were almost the same as the expectations under low input power. The output power density characteristics of the motors were high in comparison with those of the commercialized motors of PZT ceramics. It appeared that the motors have a high potential as an environmental friendly piezoelectric device with excellent properties, reflecting the high-power properties of SCNN ceramics.

Recovery of fissile materials from nuclear wastes

DOEpatents

Forsberg, Charles W.

1999-01-01

A process for recovering fissile materials such as uranium, and plutonium, and rare earth elements, from complex waste feed material, and converting the remaining wastes into a waste glass suitable for storage or disposal. The waste feed is mixed with a dissolution glass formed of lead oxide and boron oxide resulting in oxidation, dehalogenation, and dissolution of metal oxides. Carbon is added to remove lead oxide, and a boron oxide fusion melt is produced. The fusion melt is essentially devoid of organic materials and halogens, and is easily and rapidly dissolved in nitric acid. After dissolution, uranium, plutonium and rare earth elements are separated from the acid and recovered by processes such as PUREX or ion exchange. The remaining acid waste stream is vitrified to produce a waste glass suitable for storage or disposal. Potential waste feed materials include plutonium scrap and residue, miscellaneous spent nuclear fuel, and uranium fissile wastes. The initial feed materials may contain mixtures of metals, ceramics, amorphous solids, halides, organic material and other carbon-containing material.

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

Mechanics of hard films on soft substrates

NASA Astrophysics Data System (ADS)

Lu, Nanshu

2009-12-01

Flexible electronics have been developed for various applications, including paper-like electronic readers, rollable solar cells, electronic skins etc., with the merits of light weight, low cost, large area, and ruggedness. The systems may be subject to one-time or repeated large deformation during manufacturing and application. Although organic materials can be highly deformable, currently they are not able to fulfill every electronic function. Therefore flexible electronic devices are usually made as organic/inorganic hybrids, with diverse materials, complex architecture, and micro features. While the polymer substrates can recover from large deformations, thin films of electronic materials such as metals, silicon, oxides, and nitrides fracture at small strains, usually less than a few percent. Mechanics of hard films on soft substrates hence holds the key to build high-performance and highly reliable flex circuits. This thesis investigates the deformability and failure mechanisms of thin films of metallic and ceramic materials supported by soft polymeric substrates through combined experimental, theoretical, and numerical methods. When subject to tension, micron-thick metal films with stable microstructure and strong interfacial adhesion to the substrate can be stretched beyond 50% without forming cracks. They eventually rupture by a ductile transgranular fracture which involves simultaneous necking and debonding. When metal films become nanometer-thick, intergranular fracture dominates the failure mode at elongations of only a few percent. Unannealed films show unstable microstructure at room temperature when subject to mechanical loading. In this case, films also rupture at small strains but by three concurrent mechanisms: deformation-induced grain growth, strain localization at large grains, and simultaneous debonding. In contrast to metal films, ceramic films rupture by brittle mechanisms. The only way to prevent rupture of ceramic films is to reduce the

[Comparison of color reappearance between metal-ceram restoration and foundry-ceram restoration using crystaleye spectrophotometer].

PubMed

Shi, Tao; Zhang, Ning; Kong, Fan-wen; Zhan, De-song

2010-10-01

To study the color reappearance effect of metal-ceram restoration and foundry-ceram restoration using Crystaleye spectrophotometer. 58 metal-ceram restorations and 58 foundry-ceram restorations according to the result of the Crystaleye spectrophotometer were made respectively. The deltaE between restorations and natural teeth as referenced were analyzed. And satisfaction of dentists and patients were evaluated. The deltaE between metal-ceram restorations and natural teeth was 7.13 +/- 0.74. The deltaE between foundry-ceram restorations and teeth was 1.47 +/- 0.84. There were statistical differences between the deltaE (P < 0.01). The satisnatural faction of dentists and patients to the foundry-ceram restorations were higher than to the metal-ceram restorations (P < 0.05). Crystaleye spectrophotometer can provide accurate reference for foundry-ceram restoration, but for metal-ceram restoration it is not accurate.

Ceramic-like open-celled geopolymer foam as a porous substrate for water treatment catalyst

NASA Astrophysics Data System (ADS)

Kovářík, T.; Křenek, T.; Pola, M.; Rieger, D.; Kadlec, J.; Franče, P.

2017-02-01

This paper presents results from experimental study on microstructural and mechanical properties of geopolymer-based foam filters. The process for making porous ceramic-like geopolymer body was experimentally established, consists of (a) geopolymer paste synthesis, (b) ceramic filler incorporation, (c) coating of open-celled polyurethane foam with geopolymer mixture, (d) rapid setting procedure, (e) thermal treatment. Geopolymer paste was based on potassium silicate solution n(SiO2)/n(K2O)=1.6 and powder mixture of calcined kaolin and precipitated silica. Various types of ceramic granular filler (alumina, calcined schistous clay and cordierite) were tested in relation to aggregate gradation design and particle size distribution. The small amplitude oscillatory rheometry in strain controlled regime 0.01% with angular frequency 10 rad/s was applied for determination of rheology behavior of prepared mixtures. Thermal treatment conditions were applied in the temperature range 1100 - 1300 °C. The developed porous ceramic-like foam effectively served as a substrate for highly active nanoparticles of selected Fe+2 spinels. Such new-type of nanocomposite was tested as a heterogeneous catalyst for technological process of advanced oxidative degradation of resistive antibiotics occurring in waste waters.

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.