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04988 Optimization of thermal debinding from injection molded ceramic parts
12
Refractories/ceramics
(properties,
production,
applications)
continuous fihre ceramic composite materials. These results were then used to down-select the filter composition for full-scale filter fabrication and testing.
Construction and characterization of an inductive 97104979 superconducting current limiting device based on ceramic Y,Ba2Cu307--h O-rings Curras, S. R. et al. C~ogertics, 1997, 37, (IO), 653-655. The paper reports experimental results about the response of a small-scale superconducting inductive device as current limiter. The device is based on ring-shaped samples of hulk YIBazCuJO,_+ coupled to a primary c&l through a magnetic core. The samples were obtained by pressing Y,Ba2Cux0,_h powders into an O-ring shape, which reacted following the standard ceramic process. The size of the O-rings was 1 cm internal diameter, 1.6 cm external diameter., and 0.3 cm height. The response of the device was measured at liquid nitrogen temperature as a function of the type of magnetic core.. the critical current of each individual superconducting O-ring, the number of O-rings used simultaneously, the frequency of the a.c. current and the number of turns of the primary coil.
97io4984
Manufacture
of antibacterial
97104985
of ceramic
can-
Chen, R. H. L. and Parthasarathy, B. Proc. Anmr. Inr. Pittsburgh Coal Conf.. 1996, 13th, (I), 358-363. Degradation and fracturing has occurred in ceramic candle filters used in the recent demonstration plant. Preliminary examination of these ceramic filters indicated that damage of the filters may have resulted from strength degradation. This study proposes a non-destructive evaluation of the structural properties of the ceramic candle filters. A virgin Refractron filter and twelve Schumacher filters which previously tested under high pressure and high temperature at the demonstration power plant were evaluated. The vibration signatures of the ceramic filters at different degradation levels are established using transient impact response technique. Results from this study indicate that the natural frequencies of the filters can he used as an index to quantify the damage condition of the filters. These results also indicate that it is viable to use the vibration mode shapes to predict the damage location of the filters.
Manufacture
of coal fly ash-based
filtration
Jo, Y. M. and Raper, J. A. Process Saf. Environ. Prot., 1997, 75, (B3), 164170. A performance evaluation was carried out on two novel ceramic composite membrane filters, applied to high temperature gas filtration. One filter was prepared in the laboratory, coal fly ash supported by stainless steel mesh, and the other was a commercial zirconia/inconel membrane (Ceramesh). A dusty gas stream was simulated by dispersion of a typical fly ash in air. Several significant characteristics for gas filtration-such as pressure drop, cake formation and filtration efficiency-were investigated with reference to operating temperature and dust concentration. Pressure drop and cake structure were found to he affected by both the operating temperature and the dust concentration of the feed stream. Higher temperatures and higher dust concentrations lead to the formation of more porous cakes, resulting in a lower cake resistance. Both membrane filters showed high collection efficiency, 99.91% for the ash and 99.99% for the Ceramesh membranes.
97to4982 Sr-Ca-Cu-0
Glass-and glass-ceramic obtaioed in the doped Bisystem. Early stage of crystallization
Teoreanu, I. et al. Key Eng. Mater., 1997, 132-136, (Pt 2., Euro Ceramics V), 1235-1238. DTA, XRD, SEMIEDX, and IR spectroscopy were employed to study the glass forming ability and the early stage of the crystallization process in the Bi-Sr-Ca-Cu-0 system doped with PhO and BzO+ The following samples were prepared: Bil.hPh,l.4_,B,Sr~CazCuzOy with x = 0.1, 0.2, 0.3, 0.4. The samples were generally multiphased and deviations from the starting compositions were found. With increasing B content more homogeneous and stable phases were obtained. For Ph doping., the stoichiometry was close to the 2212 phase. The intensity of the exothermic events up to 700°C was reduced in the presence of the dopants. The heating rate and the oxidation of Cu’+ played important roles during the first stage of crystallization whereas the dopants influenced the processes taking place at higher temperatures, such as the partial and total melting points of the system.
97104983 PNN-PZT
Low-temperature sintering piezoelectric ceramics
mechanism
of PMN-
Zhou, S. et al. Sintering Mater., Proc. Inr. Symp. Sci. Technol. Sinreritzg, 6rh, 1995, 300-302. Edited by Li, N., International Academic Publishers, Beijing, People’s Republic of China. Isothermal sintering (ITS) has been used to investigate the densification kinetics in liquid-phase-sintered PbMp0.~3Nh~l.h703 (PMN)-PbN&~.33Nh0.h703 (PNN)-Pb(Zr, Ti)Oj (PZT) piezoelectric ceramics. The major processes with the greatest influence on sintering have been studied by TGA and DTA measurements. The kinetic parameters have been estimated from experimental data.
432
Fuel and Energy Abstracts
November
1997
ceramic materials
modulus
associated
Cheng, B. L. et al. J. Phys. IV, 1996, 6. (C8, ICI FUAS I I, Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids, 1996), 687-690. Mechanical loss Q-’ and elastic modulus measurements were used to study the phase transition in lanthanum-modified lead zirconate titanate ceramic (PLZT) of 6/60/40 composition. The shear elastic modulus measured at SO250°C shows that the Curie temperature is located at 180°C for the transition from cubic to rhomhohedral phase. A peak corresponding to such phase transition is clearly observed in the Q-’ curves at low frequencies. This phase transition is confirmed by measurements of Young’s modulus and Q-’ using resonance curve technique from -100 to 3OO’C at kilohertz. Moreover, at 50-90°C the resonance curve recorded at kHz frequency shows two resonance peaks. Such existence of double peaks means that a phase transition takes place between two rhombohedral phases FE2 and FE1 in the ferroelectric state. These phase transitions are also studied by DSC measurement.
97io4987 Experimental study of airborne particulate 97io49at using thin ceramic composite membrane filters
from fly ash
Bahlicky, D. S. African ZA 95 09,833 (Cl. C04B). II) Jul 1996. IL Appl. 111,704, 21 Nov 1994, IO pp. In the manufacture of ceramic or semi-ceramic products based on fineparticle coal fly ash, small-particle size coal fly ash, clay, organic component, and water are mixed, and the mix is cast into a desired shape. The shaped product is press-compacted, then the greenware is dried and fired to obtain the final ceramic products, which are used as decorative building materials.
97io49aa Mechanical loss and elastic with phase transitions in PLZT ceramics Evaluating structural deterioration 97104980 dle filters using dynamic response
ceramics
Fujimoto, T. et al. Jpn. Kokai Tokkyo Koho JP 09.241.017 [97,241,017] (Cl. COIB39/02),16 Sep 1997, Appl. 96150,156, 7 Mar 1996. 6 pp. (In Japanese). Fly ash is pulverized to an average particle size of I-IO I’m. It is then zeolitized and supported with antibacterial metal ions and optionally ammonium ion to produce the ceramics. The ceramics are suitable for medical goods, kitchen utensils, etc.
Metallic oxidation
in metal-ceramic
composites
Kuri, S. E. et al. Congr. Anu. Assoc. Bras. Metal. Maw., 1995, (Pub. 1996). 50, (4), 621-627. (In Portuguese) The effect of metallic oxidation on alumina-Zirconia-metal (nickel and niobium) composites is presented on this work, based on results of thermogravimetric analysis in oxygen environment with flow of 0.15 limin. Metallic oxidation of isolated metallic particles was compared with, powder oxidation of the composite. SEM was used for studies of samples after oxidation testing.
97104988 Optimization molded ceramic parts
of thermal
debinding
from
injection
Himpel, G. and Lenk, R. CFL Ceram. Forum Int., 1997, 74, (7/8), 368-371. The optimization of the removal of a polyethylene-based hinder system from injection moulded SIC thread guides and test rods was investigated. The specimens had a solids volume content of 54% and 51%. A thermal analysis of the hinder system, its components, and the injection moulded bodies was performed. In order to determine the shortest time temperature curve for defect-free hinder removal, heating/temperature defect diagrams for both were drawn up. Through knowledge of the critical heating rate/ temperature relationship, the necessary hinder removal curves can he set up dependent upon the thickness of the parts. Defect-free hinder removal of ceramic pieces is compared to hinder removal curves of powder metallurgy.
97104989 Research stable MLC ceramics
on a new kind of low-permittivity
heat-
Wu, X. el al. Proc. 1111.Conf. Elec@on. Compon. Mater., Sens. Acruatotx, 1995, 59-61. A new kind of high-performance, low-permittivity, heat-stable MLC ceramics has been developed by studying ZnO-BZ03-SiOZ ceramic system.
97104990 reinforced
Solidification processing with ceramic microspheres
of aluminum casting alloy for thixoforming
Rodrigo, P. D. D. et al. Light Met., 1997, 953-960. The paper describes the development of cast aluminium matrix composites based on an Al-Si-Mg alloy. The reinforcement consisted of hollow microspheres, a ceramic fly-ash by-product from coal power stations. The particles were incorporated into the aluminium alloy melt by mechanical stirring either in the semi-solid state or full liquid state. The composite melts were cast from full liquid temperature to produce slugs for thixoforming. The as-cast microstructure consisted of fine, equiaxed dendritic primary grains in a matrix of eutectic phases. The primary dendritic grains evolved to become non-dendritic after reheating the slugs to semisolid temperature The slugs were subsequently thixoformed at a temperature corresponding to a solid volume fraction of
Refractories/ceramics
(properties,
production,
applications)
continuous fihre ceramic composite materials. These results were then used to down-select the filter composition for full-scale filter fabrication and testing.
Construction and characterization of an inductive 97104979 superconducting current limiting device based on ceramic Y,Ba2Cu307--h O-rings Curras, S. R. et al. C~ogertics, 1997, 37, (IO), 653-655. The paper reports experimental results about the response of a small-scale superconducting inductive device as current limiter. The device is based on ring-shaped samples of hulk YIBazCuJO,_+ coupled to a primary c&l through a magnetic core. The samples were obtained by pressing Y,Ba2Cux0,_h powders into an O-ring shape, which reacted following the standard ceramic process. The size of the O-rings was 1 cm internal diameter, 1.6 cm external diameter., and 0.3 cm height. The response of the device was measured at liquid nitrogen temperature as a function of the type of magnetic core.. the critical current of each individual superconducting O-ring, the number of O-rings used simultaneously, the frequency of the a.c. current and the number of turns of the primary coil.
97io4984
Manufacture
of antibacterial
97104985
of ceramic
can-
Chen, R. H. L. and Parthasarathy, B. Proc. Anmr. Inr. Pittsburgh Coal Conf.. 1996, 13th, (I), 358-363. Degradation and fracturing has occurred in ceramic candle filters used in the recent demonstration plant. Preliminary examination of these ceramic filters indicated that damage of the filters may have resulted from strength degradation. This study proposes a non-destructive evaluation of the structural properties of the ceramic candle filters. A virgin Refractron filter and twelve Schumacher filters which previously tested under high pressure and high temperature at the demonstration power plant were evaluated. The vibration signatures of the ceramic filters at different degradation levels are established using transient impact response technique. Results from this study indicate that the natural frequencies of the filters can he used as an index to quantify the damage condition of the filters. These results also indicate that it is viable to use the vibration mode shapes to predict the damage location of the filters.
Manufacture
of coal fly ash-based
filtration
Jo, Y. M. and Raper, J. A. Process Saf. Environ. Prot., 1997, 75, (B3), 164170. A performance evaluation was carried out on two novel ceramic composite membrane filters, applied to high temperature gas filtration. One filter was prepared in the laboratory, coal fly ash supported by stainless steel mesh, and the other was a commercial zirconia/inconel membrane (Ceramesh). A dusty gas stream was simulated by dispersion of a typical fly ash in air. Several significant characteristics for gas filtration-such as pressure drop, cake formation and filtration efficiency-were investigated with reference to operating temperature and dust concentration. Pressure drop and cake structure were found to he affected by both the operating temperature and the dust concentration of the feed stream. Higher temperatures and higher dust concentrations lead to the formation of more porous cakes, resulting in a lower cake resistance. Both membrane filters showed high collection efficiency, 99.91% for the ash and 99.99% for the Ceramesh membranes.
97to4982 Sr-Ca-Cu-0
Glass-and glass-ceramic obtaioed in the doped Bisystem. Early stage of crystallization
Teoreanu, I. et al. Key Eng. Mater., 1997, 132-136, (Pt 2., Euro Ceramics V), 1235-1238. DTA, XRD, SEMIEDX, and IR spectroscopy were employed to study the glass forming ability and the early stage of the crystallization process in the Bi-Sr-Ca-Cu-0 system doped with PhO and BzO+ The following samples were prepared: Bil.hPh,l.4_,B,Sr~CazCuzOy with x = 0.1, 0.2, 0.3, 0.4. The samples were generally multiphased and deviations from the starting compositions were found. With increasing B content more homogeneous and stable phases were obtained. For Ph doping., the stoichiometry was close to the 2212 phase. The intensity of the exothermic events up to 700°C was reduced in the presence of the dopants. The heating rate and the oxidation of Cu’+ played important roles during the first stage of crystallization whereas the dopants influenced the processes taking place at higher temperatures, such as the partial and total melting points of the system.
97104983 PNN-PZT
Low-temperature sintering piezoelectric ceramics
mechanism
of PMN-
Zhou, S. et al. Sintering Mater., Proc. Inr. Symp. Sci. Technol. Sinreritzg, 6rh, 1995, 300-302. Edited by Li, N., International Academic Publishers, Beijing, People’s Republic of China. Isothermal sintering (ITS) has been used to investigate the densification kinetics in liquid-phase-sintered PbMp0.~3Nh~l.h703 (PMN)-PbN&~.33Nh0.h703 (PNN)-Pb(Zr, Ti)Oj (PZT) piezoelectric ceramics. The major processes with the greatest influence on sintering have been studied by TGA and DTA measurements. The kinetic parameters have been estimated from experimental data.
432
Fuel and Energy Abstracts
November
1997
ceramic materials
modulus
associated
Cheng, B. L. et al. J. Phys. IV, 1996, 6. (C8, ICI FUAS I I, Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids, 1996), 687-690. Mechanical loss Q-’ and elastic modulus measurements were used to study the phase transition in lanthanum-modified lead zirconate titanate ceramic (PLZT) of 6/60/40 composition. The shear elastic modulus measured at SO250°C shows that the Curie temperature is located at 180°C for the transition from cubic to rhomhohedral phase. A peak corresponding to such phase transition is clearly observed in the Q-’ curves at low frequencies. This phase transition is confirmed by measurements of Young’s modulus and Q-’ using resonance curve technique from -100 to 3OO’C at kilohertz. Moreover, at 50-90°C the resonance curve recorded at kHz frequency shows two resonance peaks. Such existence of double peaks means that a phase transition takes place between two rhombohedral phases FE2 and FE1 in the ferroelectric state. These phase transitions are also studied by DSC measurement.
97io4987 Experimental study of airborne particulate 97io49at using thin ceramic composite membrane filters
from fly ash
Bahlicky, D. S. African ZA 95 09,833 (Cl. C04B). II) Jul 1996. IL Appl. 111,704, 21 Nov 1994, IO pp. In the manufacture of ceramic or semi-ceramic products based on fineparticle coal fly ash, small-particle size coal fly ash, clay, organic component, and water are mixed, and the mix is cast into a desired shape. The shaped product is press-compacted, then the greenware is dried and fired to obtain the final ceramic products, which are used as decorative building materials.
97io49aa Mechanical loss and elastic with phase transitions in PLZT ceramics Evaluating structural deterioration 97104980 dle filters using dynamic response
ceramics
Fujimoto, T. et al. Jpn. Kokai Tokkyo Koho JP 09.241.017 [97,241,017] (Cl. COIB39/02),16 Sep 1997, Appl. 96150,156, 7 Mar 1996. 6 pp. (In Japanese). Fly ash is pulverized to an average particle size of I-IO I’m. It is then zeolitized and supported with antibacterial metal ions and optionally ammonium ion to produce the ceramics. The ceramics are suitable for medical goods, kitchen utensils, etc.
Metallic oxidation
in metal-ceramic
composites
Kuri, S. E. et al. Congr. Anu. Assoc. Bras. Metal. Maw., 1995, (Pub. 1996). 50, (4), 621-627. (In Portuguese) The effect of metallic oxidation on alumina-Zirconia-metal (nickel and niobium) composites is presented on this work, based on results of thermogravimetric analysis in oxygen environment with flow of 0.15 limin. Metallic oxidation of isolated metallic particles was compared with, powder oxidation of the composite. SEM was used for studies of samples after oxidation testing.
97104988 Optimization molded ceramic parts
of thermal
debinding
from
injection
Himpel, G. and Lenk, R. CFL Ceram. Forum Int., 1997, 74, (7/8), 368-371. The optimization of the removal of a polyethylene-based hinder system from injection moulded SIC thread guides and test rods was investigated. The specimens had a solids volume content of 54% and 51%. A thermal analysis of the hinder system, its components, and the injection moulded bodies was performed. In order to determine the shortest time temperature curve for defect-free hinder removal, heating/temperature defect diagrams for both were drawn up. Through knowledge of the critical heating rate/ temperature relationship, the necessary hinder removal curves can he set up dependent upon the thickness of the parts. Defect-free hinder removal of ceramic pieces is compared to hinder removal curves of powder metallurgy.
97104989 Research stable MLC ceramics
on a new kind of low-permittivity
heat-
Wu, X. el al. Proc. 1111.Conf. Elec@on. Compon. Mater., Sens. Acruatotx, 1995, 59-61. A new kind of high-performance, low-permittivity, heat-stable MLC ceramics has been developed by studying ZnO-BZ03-SiOZ ceramic system.
97104990 reinforced
Solidification processing with ceramic microspheres
of aluminum casting alloy for thixoforming
Rodrigo, P. D. D. et al. Light Met., 1997, 953-960. The paper describes the development of cast aluminium matrix composites based on an Al-Si-Mg alloy. The reinforcement consisted of hollow microspheres, a ceramic fly-ash by-product from coal power stations. The particles were incorporated into the aluminium alloy melt by mechanical stirring either in the semi-solid state or full liquid state. The composite melts were cast from full liquid temperature to produce slugs for thixoforming. The as-cast microstructure consisted of fine, equiaxed dendritic primary grains in a matrix of eutectic phases. The primary dendritic grains evolved to become non-dendritic after reheating the slugs to semisolid temperature The slugs were subsequently thixoformed at a temperature corresponding to a solid volume fraction of