- Email: [email protected]
Preparation and properties of binary and ternary composite solids in the clay-mica-glass system
CERAMICS
156
PREPARATION AND PROPERTIES OF BINARY AND TERNARY COMPOSITE SOLIDS IN THE CLAY-MICA-GLASS SYSTEM
STRUCTURE FORMATION DISPERSIONS V.V. Minchenko
INTERNATIONAL,
Vol. 11, n. 4,1!385
IN HEATED CLAY
and S.F. Mischenko
M.M.P. Low and P. Fazio Binary and ternary composite solids in the clay-mica-glass system have been fabricatedby combining both natural mica flakes of the phlogopite type and ground powders prepared from recycled waste glass, and clay grains and mixtures of clay-glass powders, employing a simple sintering process at temperatures in the range of 850-1050°C. Results of the study showed that these composites have very different physical appearance and material characteristics. In the glass-mica system, mixtures can be fabricated into composite solids which exhibit either a porous cellular structure or a densified ceramic structure. The mixtures can also be fabricated into multilayer structural products consisting of both the cellular structure layer and densified structure layer. In the clay-mica binary system and in the clay-mica-glass ternary system, mixtures can be readily fabricated into composite solids with low density and low thermal conductivity. All coposite solids showed excellent insulation properties and would contribute to energy conservation when used for building envelope design applications. KINETIC STUDY OF THE CRYSTALLIZATION AMORPHOUS - DERIVED Ca0n2A1203
OF
M. Vallino
COUNTER COURRENT COMPENSATION DOPED Pb(Zrr -x, Ti,)Os PIEZOELECTRIC and Bd-El-Raouf
OF DOUBLE CERAMICS
F. Tawfik
Various compositions of pure Pb(Zr/Ti)O, having Zr/Ti ratio ranging from 50150 up to 58142 were prepared by the usual ceramic technique and firing at 1400°C. The prepared materials were single doped with 0.1 wt.% lanthana and douple doped with (0.1 wt.% lanthana+O.l wt.% neodymia). Measurements of dielectric properties (constant and anisotropy), piezoelectric properties and Young’s modulus were conducted as a function of Zr/Ti ratio and type of doping. The obtained results were discussed on the bases of the effects of varying (Zr/Ti) ratio and single doping with lanthana on forcing of Pb(Zr/Ti)03 normal lattice to a defective crystal lattice having high dielectric values. Further lattice strain and defects were induced by static stress causing a generation of high piezoelectric charges at the surface of the specimens. A conclusion had been attained that Pb(Zro.55, Tio.4s)Os doped with 0.1 wt.% La203 constitutes the OptimUm composition for attaining a better quality ceramic dielectric and piezoelectrics to be used in industry for converting mechanical energy (static stress) to electrical energy (piezoelectric charges). Thus, it was possible to make use Of counter doping (compensation phenomenon) to control the desired properties and to get rid of the undesired impurities in ceramic bodies in industry which would be very profitable economically instead of chemical purification or other destructive means. A COMMENT ON THE EQUILIBRIUM SbN4 + 3CF?3SiC + 2Nz A. Kate, H. Mizumoto Short communication.
DISPERSION
OF BaTiOs POWDERS (PART I)
S. Mizuta, M. Parish and H.K. Bowen The fundamental properties of BaTi03 dispersions in pure organic liquids and water were studied by sediment volume and contact angle measurements. The liquid groups included alcohols, aidehydes, acids, esters, ketones, ethers, hydrocarbons, and water. Benzaldehyde was found to be the best dispersing medium for the commercial BaTi powders tested.
HOT-PRESSING
An amorphous-solid with a high degree of homogeneity has been prepared which, upon heating for a few hours at 850°C gives well crystallized monoclinic CA2. The amorphous material transforms into monoclinic CA2 via a phase having a y-Al203 type structure. Isotherms of transformation from the y-Al203 phase to monoclinic CA2, may be described by a first-order equation - In(l-f)= kt; the activation energy corresponding to this phase transformation is 112 &5 kcal/mol.
M.M. Abou-Sekkina
The results of an investigation of structure formation processes in mineral dispersions are given. It is shown that the thixotropic phenomenon has an important meaning in the strengthening of mineral systems without additional pressure. The conditions for achieving optimum structure under drying of mineral dispersions were revealed. The theological investigations of some minerals under high temperature was introduced, and the role of crystalline transformations of kaolinite and montmorillonite was shown affect the greatest plastic viscosity t)rof their dispersions.
and Y. Fukushige
OF
OF BORON CARBIDE
R. Angers and M. Beauvy Seven different boron carbide powders were hot-pressed between 1775 and 2575 K at pressures from 20.7 to 68.9 MPa during various times. The influence of temperature, pressure, time and heating and cooling rates on densification of these powders and on the microstructure of the hotpressed specimen were studied. It was found that temperatures above 2400 K are necessary to obtain fully dense boron carbide and that densification is strongly influenced by the characteristics of the starting powder. The cooling rate has also an effect on the density of hot-pressed specimens.
PRESSURE SINTERING UNDER 10 KBARS
OF Al20MgO
MIXTURES
K. Kodaira, S. Teramoto, S. Shimada and T. Matsushita Densification of A1203-MgO mixtures was performed under 10 kbars. Theoretically dense translucent ceramics were obtained at lOOO-1300°C for 15-60 wt% MgO and 75-40wt”/o A1203. Within this composition range, a uniform grain size of -0.5rm was obtained with the absence of abnormal grain growth. Fragmentation and rearrangement of particles take place as operative mechanisms in the initial stage of sintering.
DEVELOPMENT OF LIGHT-WEIGHT INSULATING PRODUCTS FROM THE CLAY-SAWDUST-GLASS SYSTEM
CLAY
N.M.P. Low, P. Fazio and P. Guite Employing a simple dry-pressing and sintering process, lightweight clay products with various physical, mechanical and thermal properties have been fabricated from mixtures of maplewood sawdust and local gray burning clay and mixtures of sawdust, clay and soda-lime glass grains prepared from recycled waste glass. Studies showed that thermal conductivity, compressive strength, and cold water absorption Of the sintered sawdust-clay products are significantly modified by the addition of sawdust particles to the Clay mixes. Studies also showed that portions of the clay particles can be
156
PREPARATION AND PROPERTIES OF BINARY AND TERNARY COMPOSITE SOLIDS IN THE CLAY-MICA-GLASS SYSTEM
STRUCTURE FORMATION DISPERSIONS V.V. Minchenko
INTERNATIONAL,
Vol. 11, n. 4,1!385
IN HEATED CLAY
and S.F. Mischenko
M.M.P. Low and P. Fazio Binary and ternary composite solids in the clay-mica-glass system have been fabricatedby combining both natural mica flakes of the phlogopite type and ground powders prepared from recycled waste glass, and clay grains and mixtures of clay-glass powders, employing a simple sintering process at temperatures in the range of 850-1050°C. Results of the study showed that these composites have very different physical appearance and material characteristics. In the glass-mica system, mixtures can be fabricated into composite solids which exhibit either a porous cellular structure or a densified ceramic structure. The mixtures can also be fabricated into multilayer structural products consisting of both the cellular structure layer and densified structure layer. In the clay-mica binary system and in the clay-mica-glass ternary system, mixtures can be readily fabricated into composite solids with low density and low thermal conductivity. All coposite solids showed excellent insulation properties and would contribute to energy conservation when used for building envelope design applications. KINETIC STUDY OF THE CRYSTALLIZATION AMORPHOUS - DERIVED Ca0n2A1203
OF
M. Vallino
COUNTER COURRENT COMPENSATION DOPED Pb(Zrr -x, Ti,)Os PIEZOELECTRIC and Bd-El-Raouf
OF DOUBLE CERAMICS
F. Tawfik
Various compositions of pure Pb(Zr/Ti)O, having Zr/Ti ratio ranging from 50150 up to 58142 were prepared by the usual ceramic technique and firing at 1400°C. The prepared materials were single doped with 0.1 wt.% lanthana and douple doped with (0.1 wt.% lanthana+O.l wt.% neodymia). Measurements of dielectric properties (constant and anisotropy), piezoelectric properties and Young’s modulus were conducted as a function of Zr/Ti ratio and type of doping. The obtained results were discussed on the bases of the effects of varying (Zr/Ti) ratio and single doping with lanthana on forcing of Pb(Zr/Ti)03 normal lattice to a defective crystal lattice having high dielectric values. Further lattice strain and defects were induced by static stress causing a generation of high piezoelectric charges at the surface of the specimens. A conclusion had been attained that Pb(Zro.55, Tio.4s)Os doped with 0.1 wt.% La203 constitutes the OptimUm composition for attaining a better quality ceramic dielectric and piezoelectrics to be used in industry for converting mechanical energy (static stress) to electrical energy (piezoelectric charges). Thus, it was possible to make use Of counter doping (compensation phenomenon) to control the desired properties and to get rid of the undesired impurities in ceramic bodies in industry which would be very profitable economically instead of chemical purification or other destructive means. A COMMENT ON THE EQUILIBRIUM SbN4 + 3CF?3SiC + 2Nz A. Kate, H. Mizumoto Short communication.
DISPERSION
OF BaTiOs POWDERS (PART I)
S. Mizuta, M. Parish and H.K. Bowen The fundamental properties of BaTi03 dispersions in pure organic liquids and water were studied by sediment volume and contact angle measurements. The liquid groups included alcohols, aidehydes, acids, esters, ketones, ethers, hydrocarbons, and water. Benzaldehyde was found to be the best dispersing medium for the commercial BaTi powders tested.
HOT-PRESSING
An amorphous-solid with a high degree of homogeneity has been prepared which, upon heating for a few hours at 850°C gives well crystallized monoclinic CA2. The amorphous material transforms into monoclinic CA2 via a phase having a y-Al203 type structure. Isotherms of transformation from the y-Al203 phase to monoclinic CA2, may be described by a first-order equation - In(l-f)= kt; the activation energy corresponding to this phase transformation is 112 &5 kcal/mol.
M.M. Abou-Sekkina
The results of an investigation of structure formation processes in mineral dispersions are given. It is shown that the thixotropic phenomenon has an important meaning in the strengthening of mineral systems without additional pressure. The conditions for achieving optimum structure under drying of mineral dispersions were revealed. The theological investigations of some minerals under high temperature was introduced, and the role of crystalline transformations of kaolinite and montmorillonite was shown affect the greatest plastic viscosity t)rof their dispersions.
and Y. Fukushige
OF
OF BORON CARBIDE
R. Angers and M. Beauvy Seven different boron carbide powders were hot-pressed between 1775 and 2575 K at pressures from 20.7 to 68.9 MPa during various times. The influence of temperature, pressure, time and heating and cooling rates on densification of these powders and on the microstructure of the hotpressed specimen were studied. It was found that temperatures above 2400 K are necessary to obtain fully dense boron carbide and that densification is strongly influenced by the characteristics of the starting powder. The cooling rate has also an effect on the density of hot-pressed specimens.
PRESSURE SINTERING UNDER 10 KBARS
OF Al20MgO
MIXTURES
K. Kodaira, S. Teramoto, S. Shimada and T. Matsushita Densification of A1203-MgO mixtures was performed under 10 kbars. Theoretically dense translucent ceramics were obtained at lOOO-1300°C for 15-60 wt% MgO and 75-40wt”/o A1203. Within this composition range, a uniform grain size of -0.5rm was obtained with the absence of abnormal grain growth. Fragmentation and rearrangement of particles take place as operative mechanisms in the initial stage of sintering.
DEVELOPMENT OF LIGHT-WEIGHT INSULATING PRODUCTS FROM THE CLAY-SAWDUST-GLASS SYSTEM
CLAY
N.M.P. Low, P. Fazio and P. Guite Employing a simple dry-pressing and sintering process, lightweight clay products with various physical, mechanical and thermal properties have been fabricated from mixtures of maplewood sawdust and local gray burning clay and mixtures of sawdust, clay and soda-lime glass grains prepared from recycled waste glass. Studies showed that thermal conductivity, compressive strength, and cold water absorption Of the sintered sawdust-clay products are significantly modified by the addition of sawdust particles to the Clay mixes. Studies also showed that portions of the clay particles can be