Some concentrated (CrO₃+MgO) aqua were added into zircon powder in order to improve corrosive resistance of zircon brick by both promoting the sintering of zircon and by strengthening the structure after firing at 1500°C and 1600°C in air or reduction atmosphere. Their effects on sintering and dissociation of zircon, and corrosive resistance of specimens after firing were investigated.
The results were as follows.
Concentrated (CrO₃+MgO) aqua promoted sintering of zircon without dissociation in air atmosphere, and it promoted remarkably with slight dissociation in reduction atmosphere.
And, it improved more the corrosive resistance of zircon brick, especially on slag penetration, than Cr₂O₃.

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In the recent works the procedure of monomer impregnation and in situ polymerization has improved the physical and mechanical properties of porous materials such as wood, concrete and gypsum.
The purpose of this work was to apply these technique above to fired clay bodies (base materials), which prepared by firing the bodies consisting of 63% Nopporo clay, 27% sand and 10% chamotte at temperature ranging from 800°C to 1, 000°C. This study was directed toward the correlation between polymethyl methacrylate (PMMA)-impregnation treatments for the fired bodies and their properties of bending strength, abrasion resistance, water absorption, freezethaw durability and chemical resistance. Its procedure was that MMA monomer containing 0.1-1.0% benzoyl peroxide (BPO) was impregnated into the fired specimen and polymerized by heating at 70-90°C in a closed vessel after wrapping in aluminum foil. At above 50vol% of monomer loading, polymerization was almost completely performed. It was observed in scanning electron photomicrographs that the impregnated polymer gradually deposited to the innerface of pore with increasing polymer. The physical and mechanical properties of PMMA-impregnated specimen were more improved with increasing P_p which means volume percent of pore filled with polymer. The most remarkable improvements were obtained from the specimens impregnated with MMA under vacuum, and the P_p was about 75vol%. Polymer efficiency for bending strength strongly increased when P_p reached to above 50-60vol%. The maximum value of the increase of bending strength per a gram of polymer was obtained using the specimen fired at 1, 100°C. Abrasion resistance was also improved from 120-140mg for unimpregnated specimens to 40-50mg for the impregnated ones. Water absorption decreased to less than 1.0wt% above 50-60vol% of P_p, and the impregnated specimens were not failed even after freeze-thaw test of 300 cycles.
It comes to the conclusion that polymer impregnation procedure was of great advantage to the improvement of the fired clay bodies (i.e. stone wares) of which the ceramic raw materials are relatively abounding in resources in our country.

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In order to improve the physical and mechanical properties of porous fired clay bodies, several monomer systems were impregnated into them, and polymerized in situ by thermalcatalytic method. The specimens were prepared by firing the bodies with the components of 63% Nopporo clay, 27% sand, and 10% chamotte at 1, 100°C in an electric furnace. The monomer systems consist of 90-100wt% styrene, 0-10wt% of cross-linking agent and 0-2wt% of silane-coupling agent.
The results obtained are summarized as follows:
(1) The pores of the specimens were rapidly filled with monomer up to about 70vol% under atomospheric pressure, and then, filling speed of monomer decreased. Full impregnation was obtained when the impregnation procedure was carried out under vacuum. (2) Using 0.5-1.0wt% of benzoyl peroxide or α, α′-azobis isobutyronitrile as curing agent, polymerization of impregnated monomer was completely performed at 90°C for 5hrs.
(3) Polystyrene-impregnated specimens of 85vol% P_p (percent of pore filled with polymer) had much higher bending and compressive strengths than those of unimpregnated ones (i.e. bending: 125kg/cm² and compressive: 670kg/cm² for unimpregnated specimens; bending: 250kg/cm² and compressive: 1, 490kg/cm² for the impregnated specimens). Abrasion resistance measured by weight loss method were improved from 95-105mg for unimpregnated specimens to 50-60mg for the impregnated ones. Water absorption also decreased from about 6wt% to 0.2wt%. (4) Using the styrene monomer containing 5-10wt% of cross-linking agents such as DAP, DVB, TMPTMA, TAIC, TAC and DAM, most of the properties of the impregnated specimens indicated more improved physical and mechanical properties. In particular, DVB, TMPTMA and TAC of them brought about 20% increase of the bending strength in comparison with the specimens impregnated with styrene only. (5) The styrene with 0.1-2.0wt% silane-coupling agent brought the increase of the bending and compressive strength up to 420-450kg/cm² and 1, 700-2, 100kg/cm² respectively. (6) The styrene containing 1% silane-coupling agent and 5-10% DVB or TMPTMA was the most effective monomer system of them for improving the mechanical properties (i.e. 500-580kg/cm² for the bending strength; 2, 000-2, 300kg/cm² for the compressive strength). Thus, it may be concluded that this silane-coupling agent plays an important role in promoting the interaction between fired body and polymer.

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Nearly pore-free β-alumina polycrystal was press-forged under uniaxial compressive load. The polycrystals deformed plastically under the uniaxial load of 100-250kg/cm² at 1700-1930°C for 10-30 minutes without failure. During the deformation, each grain in the polycrystal elongated to the perpendicular direction to the press-forging direction. X-ray diffraction patterns from the surface of press-forged polycrystals perpendicular to the forging direction showed that the orientation degree of c-plane of each crystal grain could be about 0.6 in some cases. In order to obtain a polycrystal which has higher orientation degree, the press-forged polycrystals were annealed at 1850-1880°C for 1-3 hours. During the annealing treatment, the crystal grains showed topotaxial growth from the original elongated grains, and the orientation degree changed from 0.59 to 0.81 in a case. The orientated polycrystalline β-alumina showed the anisotropic ionic conduction of Na between the perpendicular and parallel direction to the press-forging direction. The ionic conductivity for the perpendicular direction to the press-forging direction was ten times as great as that for the parallel direction.

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The effects of V₂O₅ and B₂O₃ additives on the densification of Zn₂SnO₄ have been discussed from the results of the isothermal shrinkage and grain size measurements. Compacts pressed at 400kg/cm² were sintered in the range of 1200 to 1400°C in air. The shrinkage was determined by measuring the diameter of the compacts before and after sintering, and the grain size in the sintered compacts was measured by the electron microscopy. The results of the shrinkage measurement without oxide additives indicated that the densification in the initial stage is controlled by the bulk diffusion with the activation energy of 130kcal/mol. The rate of grain growth was found to be followed by the equation, D³=Kt (D: diameter of grain, K: rate constant, t: time), and the value of its activation energy was estimated to be 150kcal/mol.
It was found in the case of the V₂O₅ and B₂O₃ additives that the densification can be represented by three processes which are typical of the densification in the liquid phase; the first: rearrangement, the second: solution-precipitation, the final: coalescence, and that the liquid phase of V₂O₅ and B₂O₃ greatly accelerates the densification Zn₂SnO₄ via these processes. The rate of the second process was considered to be controlled by the diffusion through the liquid phase, and the values of the activation energy were 75kcal/mol and 26kcal/mol for the diffusion rate in the liquid phase of V₂O₅ and B₂O₃, respectively.

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Single crystals of BiSbO₄ were grown by heating the mixtures of Sb₂O₃ and Bi₂O₃ at 900-1200°C for 320 minutes in a Tamman tube. Obtained crystals were colorless and transparent having maximum size of 1mm in width and 14mm in length. Yields of the crystals increased linearly with reaction time and reached finally to about 70%.
According to the mass spectrum analysis for the vapor species evolved from the mixtures under growing conditions, the vapor species were Sb₄O₆, Bi, Bi₂ and BiO. Therefore, it is concluded that these vapor species react with oxygen in air to produce BiSbO₄ single crystals.
The growth direction of the crystals was along the a-axis. The lattice constants of the crystals obtained from the mixtures of stoichiometric composition were as follows,
a=5.45₅Å, b=4.87₉Å, c=11.8₂Å, β=101.0°.
The elemental analysis for the crystals indicated that Bi/Sb in the crystals reduced with the decrease of Bi₂O₃/Sb₂O₃ in the mixtures. Thus, Bi³⁺ sites in the BiSbO₄ may be partly substituted by Sb³⁺ under the presence of excess Sb₂O₃ in the mixtures. The density of the crystals obtained from the mixtures of stoichiometric composition was 8.41g/cm³ in accordance with theoretical value, 8.49g/cm³.

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Forsterite ceramic-to-Ti metal seals were formed by reactive alloying method utilizing Ti-Ni and the interfaces between the materials were examined by an optical microscope and an electron prove microanalyzer.
The results were as follows:
(1) The highest seal strength was 50kg/cm² for the samples sealed at 1000°C for 5 minutes.
(2) The intermediate layer about 3μ thick was formed at the interface between forsterite ceramic and Ti-Ni solder.
(3) Ti was absorbed selectively at the interface between forsterite ceramic and Ti-Ni solder, and Ti concentration was higher than Ni concentration in this region. Ti diffused into the ceramic about 5μ deep.
(4) These evidences and thermodynamical consideration showed that SiO₂ could react with Ti to form oxides of Ti and elemental Si. The interdiffusion and reaction between elemental Si, Ti, the oxides of Si, Ti and Mg formed intermediate and diffusion layers giving vacuumtight and mechanically stable seals.

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