Active carbonaceous fine powders were prepared by a distillation of a coal-tar pitch at various temperature and by a subsequent extraction with benzene. A high-dense, high-strength and isotropic carbon block was successfully manufactured with no-binder by the usual sintering method of oxide ceramics. In this study BS (benzene soluble)-fraction does not improve the green density, and the amount of excess BS-fraction is responsible for foaming and deformation of a carbon block during heat-treatment. Therefore it was found BS-fraction was not necessary to be contained in a moulding method. On the other hand, β-fraction, which is not dissolved in benzene but is dissolved in qinoline, promotes the shrinkage of carbon block during heattreatment, and develops its strength. Sintering behavior of β-fraction is apparently like a liquid-phase sintering.
For example, the powder which was prepared by distillating at 500°C and extracting with benzene, was pressed at 2800kg/cm², and then heated up to 1800°C. The resulting carbon block was isotropic; its bulk density was 1.91g/cm³ and the compressive strength was 2610kg/cm².

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The iron naphthenate coated on a glass substrate thermally decomposed to Fe₃O₄, γ-Fe₂O₃ and α-Fe₂O₃ films by the calcination at a temperature range from 200 to 800°C. These iron oxide films were examined by X-ray diffractometry, colorimetric analysis and electron microscopy.
The details of the change of iron oxides prepared on the films were as follows:
1) The solid solution of Fe₃O₄-γ-Fe₂O₃ system crystallized at the temperature range from 250 to 400°C. The lattice constant of the solid solution continuously decreased and the degree of oxidation increased as the calcination temperature rose up to 400°C.
2) The pure γ-Fe₂O₃(a₀=8.338Å) crystallized at the temperature range from 450 to 500°C for 4h. This γ-Fe₂O₃ was stable on calcining over long time at this temperature range.
3) The γ-Fe₂O₃ transformed to α-Fe₂O₃ above 500°C with the increase in the grain size. The amount of α-Fe₂O₃ increased with a rise in the calcination temperature and time.
4) The color of the film obtained below 500°C was yellowish brown. The color changed to brownish red above 550°C, because the γ-Fe₂O₃ transformed to α-Fe₂O₃.
5) The thickness of the film prepared above 400°C ranged between 2000-2500Å.

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The hot-pressing with magnesium compounds in Mg-Si-N-O system as additives was studied experimentally at about 1800°C and following conclusions were obtained.
1. Rapid densification was observed when a composition of secondary phase formed by the reaction between Si₃N₄ and additives was in a system, MgSiN₂-Mg₂SiO₄.
2. The secondary phase being only MgSiN₂, rapid grain growth took place and the densification in the later stage was hindered.
3. When the oxygen contents of the secondary phase exceeded the composition, Mg₂SiO₄, the grain growth was suppressed and the rate of densification in the initial stage of sintering was decreased.
4. Magnesium silicon nitride was formed by the reaction between MgO and Si₃N₄ and the following reaction was expected to occur above 1600°C.
4MgO+Si₃N₄→2MgSiN₂+Mg₂SiO₄
5. Magnesium compounds in Mg-Si-N-O system added seem to show little solid solubility in Si₃N₄ even at 1800°C.

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The solid solution was formed between CoO⋅Al₂O₃ and Al₂O₃ above 1200°C. The solid solubility of Al₂O₃ in the spinel lattice was measured by the change of the lattice constant of the spinel.
The limits of solid solution were determined from the lattice constants of CoO⋅nAl₂O₃ of which the compositions were known.
Measured lattice constants and caluculated n-values of CoO⋅nAl₂O₃ were 8.059 Å to 1.41, 8.025 Å to 1.88, 7.990 Å to 2.61 and 7.972 Å to 3.12, and the temperature were 1600°C, 1700°C, 1800°C and 1850°C respectively.
Based on this result, the subsolidus phase relation of the system CoO⋅Al₂O₃-Al₂O₃ was drawn as shown in Fig. 4.

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The authors propose a new model which shows the mechanical behavior of plastic clay bodies. The model is composed of two parts, “I” and “R”, arranged in series. Part “I” contributes to the spontaneous elastic deformation and is constituted by many spring elements stood in a row, while part “R” contributes to the retarded elastic deformation and is constituted by many spring elements and dashpot elements all stood in a row. In our last paper we have mentioned how part “I” behaves when the external force is applied, i.e., some of the spring elements in part “I” are decayed, so the residual ones, fraction of which is inversely proportional to the exponential function of the stress, support the total stress.
Now, the spring elements decayed by the application of the external force, are changed into the dashpot elements immediately. All these new dashpot elements are arranged in series and this group is called part “R′”. This part joins to the part “R” arranging in a row. Because the external force is applied to parts “R” and “R′” as well as part “I”, some of the dashpot elements in part “R′” are decayed and disappeared in proportion to the strength of the external force. Supposing thus, the mechanical behavior expected from our new model agreed well with the results of our creep tests on a plastic clay body. The obtained results are summarized as follows:
1. If unit stress is increased, the spring elements decay linearly with the inverse of the increase of moisture content (dry basis).
2. At the constant moisture content the compliance for the delayed elasticity is linear to the delayed strain and the former increases with the latter.
3. The viscosity of the paste is linear to the delayed strain and the slope of this straight line depends very much on the stress. As the stress increases, the line approaches to the strain axis, until parallel to the axis when the stress is enough high. The viscosity is very sensitive to the moisture content.

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Translucent aluminum oxide-to-tantalum metal seals were formed using an oxide solder and interfaces between the materials were examined by an optical microscope, scanning type electron microscope and an electron microprobe analyzer. The solder was a glass composed of CaO, Al₂O₃, SiO₂, MgO, SrO, Na₂O and K₂O. The results were as follows:
(1) Vacuum tight seals were formed by this technique.
(2) The solder which turned into a glass-ceramic composite by sealing operation contained 2CaO⋅Al₂O₃⋅SiO₂ (gehlenite) as main constituent phase.
(3) The crystal showed dendritic appearance in contrast to those in niobium-to-aluminum oxide seals which had showed squarish appearance.
(4) Intermediate layer 1-7μm thick was formed at aluminum oxide-solder interface.
(5) Thickness of the intermediate layer at tantalum-aluminum oxide interface was about 10μm and was comparable to those at niobium-aluminum oxide interface. The thickness, however, was far larger than those in the cases of solders which had contained no alkali (0.5μm).
(6) Concentration gradients of Al and Ta were found in the intermediate layers. These layers seemed useful in reducing sealing stress and in improving adhesion.

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The effect of starting materials on the formation of Zn₂SnO₄ crystals by vapor phase method and formation reaction were discussed.
As starting material the ZnO-Sn system and Zn-SnO₂ system were found to be superior. Of various combinations of all starting materials stoichiometric mixing ratio for the formation reaction of Zn₂SnO₄ gave the maximum yield of crystals.
It was estimated that a reaction temperature of about 1200°C with a heating time of 2-3h were the most suitable conditions for this crystal forming reaction.
It was estimated that vaporizing species of all starting materials were Zn and SnO which had about the same vapor pressure at 1200°C. From the grown state of crystals it was surmised that these vaporizing species formed as dendrites at first at the upper part of porcelain crucible with a high concentration of oxygen, after which the oxygen diffused down through the layer of dendrites to the lower part of crucible to form needle crystals.

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This study was concerned with the formation and color development of the spinel solid solution in CoO-MgO-Al₂O₃-Cr₂O₃-TiO₂ system, and its application to colored glazes.
Specimens were prepared by calcining the oxide and hydroxide mixture at 1450°C for 1h. The formation of spinel solid solution was examined by X-ray diffraction, the color was discussed by measuring the spectral reflectance, and the stability of the spinel in glazes was tested.
The results were summarized as follows.
1) Formation of a continuous solid solution was confirmed by X-ray analysis.
2) As the amount of Cr³⁺ increased in MgO-Cr₂O₃-TiO₂ system, the color changed from white through leaf to grayish leaf, and the absorption of Cr³⁺ shifted towards short wavelength region.
3) An increase of Al³⁺ in MgO-Cr₂O₃-Al₂O₃ system, caused the color to change from grayish leaf through grayish yellow and pink to white, and the absorption of Cr³⁺ shifted towards short wavelength region.
4) The color developed in MgO-Al₂O₃-Cr₂O₃-TiO₂ system, ranged from leaf through grayish leaf to grayish yellow.
5) An increase of Cr³⁺ in Coo-MgO-Cr₂O₃-TiO₂ system, yielded the colors ranging from turquoise through dull green to turquoise, and the absorption of Cr³⁺ and Co²⁺ shifted towards short wavelength region.
6) As the amount of Al³⁺ increased in Coo-MgO-Cr₂O₃-Al₂O₃ system, the colors ranging from turquoise through strong greenish blue to bright purplish blue developed, and the absorption of Cr³⁺ and Co²⁺ shifted towards short wavelength region.
7) As the amount of Al³⁺ increased in CoO-MgO-Al₂O₃-TiO₂ system, the color changed from turquoise through dull greenish blue to bright purplish blue, and the absorption of Co²⁺ shifted towards short wavelength region.
8) The colors ranging from turquoise through green to bright blue developed in CoO-MgO-Al₂O₃-Cr₂O₃-TiO₂ system.
9) According to the result of the colored glaze test, formation of a new spinel was observed in magnesia-lime glaze, and brilliant hue similar to peacock developed over the wide range of CoO-MgO-Al₂O₃-Cr₂O₃-TiO₂ system in lime glaze. Specimens with the composition of Cr³⁺ rich region were stable as a glaze stain.

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A kinetic study was made on the hydrothermal reaction between lime and quartz, and in this reaction the effects of CaO/SiO₂ ratio, particle size of quartz and added kaolin were discussed. Quartz powders with 1.5-2.5μm, 2.5-3.5μm and 3.5-5.0μm in particle radius were mixed with lime in molar ratio 1:0.8 and 1:1.2, pelletised and then autoclaved at 181°C for 0.5-24h.
Unreacted lime, unreacted quartz, combined alumina and combined water of the specimens were determined. The chemical composition of the products, rates of reaction and depths of the reacted quartz were calculated from the experimental data. It was found that the reaction of lime was controlled by dissolution and that the reaction of quartz was controlled by diffusion through the products layer arround each quartz grain.
When kaolin was added, the reaction ratio of quartz became low until all of the kaolin had reacted.

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[in Japanese]

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