メタンガスを原料として, 析出基板に直接電気を通して加熱する方式により, 析出温度1400°-2000℃, ガス圧10-200Torrの範囲で熱分解黒鉛を製作し, X線回折により表面層および内部のc軸の軸方向の面間距離, 結晶子の大きさ, 結晶子の配向性を測定した. その結果, 表面からある距離までは, 内部に進むにつれて, 黒鉛化が増大し, この傾向は析出温度が高いほど著しいこと, 表面からある距離より内部に入ると黒鉛化の増大の傾向は減少する現象が析出温度の高い場合に見られる. 析出した熱分解黒鉛が十分に厚ければ, すべての熱分解黒鉛に同様な現象が見られると予想されること, 結晶子の配向性も内部に進むにつれて良くなること, 析出ガス圧は, 表面から内部に進むにつれて黒鉛化が増大する現象に余り影響しない. 表面部と内部との黒鉛化の相違は, 高温 (2400℃)・短時間の熱処理もしくは, 中温, 長時間の熱処理で解消することができ, 得られた製品は両者の熱処理で多少の差があることなどが判明した.

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Hot-pressed zirconium diboride compacts which had four kinds of relative densities were heated in graphite at temperatures ranging from 1400°C to 2500°C. The surfaces of the heated compacts and their textures were examined by X-ray diffraction and optical microscope. Weight and relative density as well as average grain size of each compact were then measured.
Through heating at the lower temperatures ZrO₂ appeared on the surface of the compacts and then changed to ZrC at the temperatures between 1700°C and 1800°C. Lattice constants of ZrC changed to the normal values from the smaller ones with increasing temperatures. From this fact, it was supposed that ZrN was also formed simultaneously in this temperature range and made solid-solution with ZrC. While oriented graphite layers covered the surfaces of the compacts heated at temperatures above 2400°C, thin films of graphite were observed over the molten surfaces of the compacts heated at 2500°C.
Relative density of each compact reached about 0.97 when it was heated at 2500°C for 100 min. Data on grain growth were processed under the application of the following equation:
D²-D₀²=kt^m,
the value of m being either 0.66-0.78 or about 1 for heating temperatures of 2100°-2300°C or 2400°C. When the compact was heated at 2300°C, grain growth was rapid at the surface layer compared with the inner part and the m reached about 1 at this layer.
Grain growth rate constant, k in the above equation increased with the increase in the initial densities of the compacts. But the same temperature dependence was obtained for all the compacts heated at the temperatures between 2100°C and 2300°C. The activation energy in the process of grain growth was calculated to be about 60kcal/mol.

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Following the previous report on the system of B₂O₃-GeO₂, we studied some properties of B₂O₃-Sb₂O₃ glasses, as a glass-forming system, with the interest of Sb₂O₃ glass. In the first the valence of Sb in those glasses was examined. Sb₂O₃ reacts with the oxygen in air to give Sb₂O₄ at the temperature range from 400° to 500°C, as shown in Fig. 1. The melting temperature of this glass-system is about 700°C, and this temperature is in the stable range of Sb₂O₄. By the chemical analysis of the glasses dissolved in HCl, it is concluded that the valency of Sb is almost trivalent (Table 1). It was difficult to prepare the glasses from Sb₂O₄, instead of Sb₂O₃, without a long melting process, and the resulting glasses contained a negligible amount of Sb^v (Table 2). Now it is assumed that the trivalent Sb ion is stable in B₂O₃-Sb₂O₃ glasses.
We then studied the expansion coefficient of these glasses. As the results are shown in Fig. 3, the curve of the thermal expansion has the minimum at 20mol% of Sb₂O₃. In Fig. 4 this curve is compared with those of B₂O₃-SiO₂ and B₂O₃-CeO₂ systems. The deviation of these experimental curves from the straight lines jointing both their ends, represents the structurl decrease in the thermal expansion. As the deviations in the above three systems are nearly same, we consider, the reason of the decrease in the B₂O₃-Sb₂O₃ system is the same as in other systems. Namely, 4-coordinated Sb, which may be formed by an additional coordination, interferes with the thermal vibrations of B₂O₃.
The temperature of the deformation, temperature of the transition, the density and the refractive index in this system are shown in Figs. 5, 7 and 8. It is noted that in the Sb₂O₃ rich range the increase of Sb₂O₃ lowers the transition temperature of glasses and on the contrary raises their liquidus temperature. Accordingly, it is assumed, the viscosity of Sb₂O₃ melt is low at the melting point and therefore the Sb₂O₃ glass may have a chain structure. The infrared spectra of the vitreous state and two crystalline states of Sb₂O₃ are shown in Fig. 9 and these spectra of B₂O₃-Sb₂O₃ glasses are shown in Fig. 10.
From the data of DTA and of the infrared spectra, it is considered that the structure of glassy Sb₂O₃ resembles the valentinite (see Fig. 2 b). In the DTA curves of Sb₂O₃ glasses containing B₂O₃ from 0 to 30mol%, shown in Fig. 11, the first endothermic peak A, the following exothermic peak B and the last endothermic peak E indicate the glass-transition, the crystalization and the melting, respectively.
The small endothermic peak D, which appears about the transition temperature of 570°C from the senarmontite to the valentinite, means this transition, because the same peak is found in the crystalline Sb₂O₃. The other small endothermic peak C seems to correspond to the reverse transition. It is confirmed by the change in the infrared spectra of Sb₂O₃ glass treated at 400°C (Fig. 12). Namely, the peak of the valentinite decrease with time and simultaneously the peak of the senarmontite increase progressively. We concluded that the glassy Sb₂O₃ devitrifies into the valentinite and then transforms into the senarmontite, the stable phase.

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The weight loss in nitrogen atmosphere of compact mixed powders of MgO and carbon at temperatures 1400°-1800°C was followed thermogravimetrically.
At any given temperature, the reaction proceeded as a first order reaction (activation energy, 43.8kcal/mole) in an early stage, and zero order reaction followed (53.8kcal/mole). It is considered that the zero order reaction is the characteristic of the reaction of this system, and it will be explained as the effusion of gas evolved in the compact from the surface pores at constant rate (1.3mg⋅cm^-2⋅min^-1 at 1700°C) irrespective of mixing ratio, shaping pressure, or sample weight. The partial pressure of gas in the compact was obtained from the Knudsen effusion equation. For 1700°C, 4.24×10^-6 atm was found, and it corresponds to the vapor pressure of MgO at the same temperature.

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Preliminary studies were made on the effects of high explosive (tetryl) detonation shock wave on powder materials. By the explosive compaction of mixed powder of metals (Ti, Zr, and Si powders) and colloidal graphite, metal carbides were produced. But under the same condition ZrO₂ powder did not react with the colloidal graphite.
Strong sintered body (>90% T. D.) was produced from each powder by the treatment. In case of ZrO₂ powder compaction, crushing of grains were observed, and the grain crystals were colored according to the magnitude of the detonation energy.
Measurements of the variation of micro Vickers hardness proved to be just like the case of work hardening.
In such a study, the most important technical problem is how to converge the shock wave most effectively on the specimen, so we tried to estimate the distribution of pressure and temperature in the sample holder, as accurate as possible.

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