本論文はSiCバリスタの非直線特性におよぼす焼成雰囲気と添加Cu₂Oの影響についてのべる. 非直線特性はI=(V/C)^αの式で表示される. 空気中焼成のSiCバリスタは低抵抗で大きなα値を示すが, αが電流増加にともなって著しく小さくなるという性質をもっている.
これに対してH₂やN₂の非酸化性雰囲気中で焼成したものは高抵抗でαが小さく, 電流とともにαの減少する度合いはわずかである. N₂中の酸素分圧はバリスタの抵抗値に大きな影響をおよぼす, 5mmHg附近の酸素分圧における抵抗値がもっとも小さい. バリスタに少量のCu₂Oを加えてN₂またはH₂中で焼成すると, 低抵抗で高αの素子が得られ, しかもこのαは電流に対して一定である. 添加Cu₂Oの効果はX-線マイクロアナライザの結果をもとにして論ぜられている.

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チタン (III) 固溶コランダムを1300℃空気中で加熱し, [0001] 軸にほほ直角および平行な面の形態変化を反射光学および電子顕微鏡によって観察した. 被検面は加熱前に化学的にエッチングした. 諸観察結果中, 双晶接合面, または双晶接合面類似界面と (0001) 面の交線に沿ってコランダムからなると思われる畝の生成したことが注目された. この畝の生成原因について予備的考察を行った.

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Initial-stage sintering of the active BeO powder was investigated by measuring the isothermal shrinkage of its powder compacts continuously with a thermo-dilatometer consisting of a linear variable differential transformer activating an X-Y recorder, in vacuum for the temperature range 1250° to 1450°C.
The results obtained were summarized as follows:
(1) Initial-stage sintering of the active BeO powder was found to be a rapid densification process represented by the straight line with a slope of unity, when logarithm shrinkage was plotted against logarithm time.
(2) Large amounts of the initial shrinkage for a short time period due to this process markedly shortened the time to complete the densification. The phenomenon showed characteristically one of many properties of the active BeO powder, which is considered to be sinterable.
(3) This process was followed by the neck growth due to vacancy-volume diffusion.

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Powder mixtures of zirconium diboride and lanthanum hexaboride were hot-pressed at the temperatures ranging from 1700° to 2200°C in graphite mould under the pressure of 200kg/cm². During hot-pressing at temperatures below 2000°C, shrinkage of the compact was measured by means of dial gauge which was connected with the ram table of hot-press furnace. The ram table moved in consequence of the densification of the compact at high temperatures.
Final density was measured and density change of the compact during hot-pressing was calculated. Microstructures were observed with microscope and electron probe microanalyzer.
Densification of zirconium boride compacts was accelerated by addition of 3 wt% lanthanum boride and the effect was seemed to be mostly due to quicker densification of lanthanum boride. From the densification data, log (1-ρ) were plotted against t according to Murray's equation and fairly good linearities were observed between them except the early period. The viscosities, η, of the compacts were calculated from the slopes of the above mentioned plots. On the basis of their temperature dependences activation energies were observed to be 76kcal/mol for zirconium boride compact, 68kcal/mol for zirconium boride compact with 10 wt% lanthanum boride and 60kcal/mol for lanthanum boride compact, respectively.
Mutual penetration of Zr or La element to another boride particles was not detected. These compacts did not show good oxidation resistance.

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Mullite specimens were subjected to corrosion at high temperatures by alkaline (Na₂CO₃) vapor and many kinds of reaction products were formed containing corundum, nepheline, carnegieite, carnegieite-sodium aluminate solid solution and sodium aluminate.
In the first stage of the corrosion process, mullite decomposed into carnegieite and corundum. As the supply of alkaline vapor was continued, the latter gradually changed into sodium aluminate, which in turn dissolved into carnegieite to form carnegieite-sodium aluminate solid solution.
In the low content of sodium aluminate, that solid solution could be converted, on cooling, to nepheline structure like as the case with pure carnegieite. With increasing amount of sodium aluminate, it was found to disturb this conversion and to stabilize the solid solution as carnegieite.
The final crystalline product by the corrosion was sodium aluminate. However, after a long time of exposure to the alkaline vapor, this phase gradually changed into glassy phase resulting in the wear of mullite refractory.

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