Magnesite refractories reacted with SO₃ gas to form MgSO₄ as solid phase. When Na₂SO₄ existed, however, the MgSO₄ reacted with Na₂SO₄ to form liquid at above 670°C. Over the range of 670°C to 814°C, Na₂SO₄⋅3MgSO₄ crystallized from liquid with proceeding of the reaction, but at above 814°C, did not. As a result of formation of liquid, the amount of SO₃ picked up by the refractories increased particularly at 814°C to 1000°C and was maximum about 1000°C, but at above the temperature it decreased. Liquid formed by the reaction was transformed into Na₂SO₄⋅3MgSO₄ and MgSO₄ during cooling.
When K₂SO₄ existed, reaction of the refractories with SO₃ gas was similar to the reaction in the case of existing of Na₂SO₄. Over the range 884°C to 1000°C the amount of SO₃ picked up by the refractories was particularly increased and liquid formed by the reaction was transformed into K₂SO₄⋅2MgSO₄ and MgSO₄ during cooling.

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The noncrystalline materials of the system SiO₂-Al₂O₃-K₂O were heat-treated at 1200°C-1600°C, and the inversion temperature of tetragonal→←cubic phases, the lattice constants and the amount of leucite crystals precipitated in the noncrystalline materials were measured by using DTA apparatus and X-ray diffractometer.
It was found that the inversion temperature varied in the wide rage of 404°C to 628°C with the atomic ratio δ=Si/Si+Al+K of the noncrystalline material and the crystallization temperature. Each leucite precipitated in the noncrystalline materials with δ<0.5 showed a constant inversion temperature 621±7°C corresponding to that of the leucite with stoichiometric composition. Inversion temperature of leucite precipitated in the noncrystalline materials with δ>0.5 lowered with the increase of δ and with the decrease of crystallization temperature and the lattice parameter c/a tend to decrease with inversion temperature.
It was concluded that in the case of δ>0.5, the leucite crystals having the composition of (KAl)_1-xSi_2+xO₆ (x>0) had a higher symmetrical lattice than the stoichiometric one and the lattice defects which might be caused by the defficiencies of potassium ions increasing with δ.
The shift of AlK_α peak of the leucite crystals prepared was also measured by the X-ray fluorecence spectrometer. The results indicated that the aluminum ions in the leucite crystals were in fourfold coordination.

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Polycrystalline Ni_0.5Zn_0.5Fe₂O₄ was deformed under the bending stress of 11kg/cm²⋅min from room temperature to 1400°C. Below 600°C, the fracture of polycystals was completely brittle and the fractured surface was mostly transgranular. In the temperature range between 800°C and 1300°C, the relative contribution of intergranular failure increased with increasing temperature. The temperature at which the intergranular failure increased coincided with that at which internal friction of grain boundary increased. The brittle-ductile transition temperature under bending stress was about 1200°C, the same as the transition temperature under compressing stress. Above 1350°C, the fracture stress decreased rapidly with increasing temperature, and the fracture stress under bending stress was the same as that under compressing stress, and the fracture was entirely intergranular.
Grain boundary slip was not large enough to be detected by the off-set of the marker line. Grain boundary was too brittle to slip at low temperatures, and was so plastic above 1350°C that it easily migrated and corrugated preventing the boundary slip. Only in the intermediate temperature range around 1300°C, slight grain boundary slip was observed by the off-sef of the marker line.

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The resistivity against frost action in ceramics has usually been examined by freezing and thawing under three dimensional-cooling. But, it seems to be reasonable to examine under one dimensional-cooling, because structural materials are generally exposed under such a condition of one dimensional-cooling. Standing on this point of view, it was aimed to compare the appearances of frost damages caused under three dimensional- and one dimensional-cooling.
As the results of investigation on an insulator brick, a roofing tile body, a wall tile and an earthenware body, several differences in the nature of frost damages between the two cooling methods have been elucidated as follows:
(1) Provided that there is no directional difference in strength resulting from lamination and/or preferred orientation of particles in ceramic bodies, stratified cracks perpendicular to the cooling direction are developed under one directional-cooling, while under three dimensional-cooling non-stratified, random cracks are formed.
(2) The stratified cracks stem plausibly from the preferred growth of ice along the cooling direction. This thought is strongly supported by the preferred expansion along the cooling direction observed on a model system in which thin glass plates are stacked together holding water films between them.
(3) Under one dimensional-cooling the lower the rate of cooling the more severe damages occurs, while under three dimensional-cooling the higher rate of cooling causes the more severe damages.
(4) Regardless of the two cooling methods, cracks develop along the direction of lower bonding strength in ceramic materials resulting from, if any, lamination and/or particle orientation.

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Reaction-sintered bodies of β-SiC were prepared in vacuum by impregnation of gaseous or liquid silicon into the following powder compacts; non-graphitizable carbon, artificial graphite and colloidal graphite. Microstructure of the resulting reaction-sintered bodies were observed with electron microscope and reflected optical microscope, and then it was found that the microstructure of reaction-sintered body by gaseous silicon differed greatly from that of reaction-sintered body by liquid silicon. The microstructure of the former could be explained on the basis of multi-grain-coalescence model which was previously proposed by the authors, while the microstructure of the latter was resulted from a predominant action of liquid silicon in the solution-precipitation mechanism.

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安定化ジルコニアの電圧-電流-時間特性を480-650℃アルゴン雰囲気中で, 白金点電極を用いて測定した. 用いた電圧は20-90ボルトであり, 白金電極を通して酸素の供給量が, ジルコニア試料中の酸素イオン移動量よりはるかに少ないという条件を満たす. 電流-時間特性は3段階にわかれている. 第1段階は, ゆるやかな電流増加であり, 着色部分がカソード部から成長している. 着色部の先端がアノードに到着した点が第2段階への転移点である. 第1段階での電流ばイオン電流である. 第2段階での電流増加率ば電流値自身に比例する. この段階での電流は電子電流であり, 電子の易動度は1.6×10^-6cm²/V・sec (580℃) と算定された. 第3段階は絶縁破壊であり, 着色した導電径路の芯の着色が濃くなるが, 金属ジルコニウムの析出は認められなかった.

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La₂O₃-Y₂O₃系の液相線を, ヘリオスタット式太陽炉を用い鏡面反射法により冷却曲線を求め, これより算定した. 熔融後急冷した試料をX線回折および偏光顕微鏡により検討した.
この系の凝固点の測定結果を示し, また液相線下において40-73mol% La₂O₃組成間にLaYO₃固溶体領域が観察された.
他の相はLa₂O₃固溶体, La₂O₃+LaYO₃固溶体, LaYO₃+Y₂O₃固溶体およびY₂O₃固溶体であった.
各配合組成の試料を1300℃-1700℃に加熱処理, および熔融した試料からLaYO₃の単一相が観察された.
LaYO₃ (m.p. 2040±15℃) は高温X線回折を行った結果, 1450℃附近において斜方晶系〓単斜晶系に可逆転移することを認めた.
La₂O₃-Y₂O₃系の高温平衡状態図を提案する.

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