Thermal expansion at temperatures up to 1000°C was determined for pressed powders of fire clays, stony substances, and their mixtures. The thermal expansion curves obtained for their mixtures did not agree with those calculated from those of their components by assuming the additive relationship. A mechanism which explains this result was described.

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Smelting of chromium molybdenum steel was made in an arc-furnace with the bottom paved, by stamping, with electrically fused dunite. The degree of erosion of the stamped dunite was determined by the change of the composition of slag during smelting operation and also by the change of the appearence of the furnace bottom after smelting. It was found that the degree of erosion was almost the same with the case in which conventional dolomite or magnesia was used. The disadvantage in using the stamped dunite was dissolution of a trace of sulfur contaminated in the dunite into steel, which should be avoided in making non-sulfur steel. Use of electrically fused dunite of extremely low sulfur content, or purification of dunite by washing or acid-pickling was found to be effective for avoiding contamination of steel by sulfur.

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A radioisotope technique was used for the determination of the rate of movement of Ca²⁺ and Fe³⁺ ions in MgO added with or without a small amount of SiO₂, Al₂O₃, etc. As the tracers RI⁴⁵Ca and RI⁵⁹Fe were used. The relationship between the rate of movement of these ions and the sintering behaviors of the mixtures were also studied.
The results obtained were summarized as follows:
(1) The movement of these ions is caused by thermal diffusion and draining. In MgO added with CaO and SiO₂, the rate of movement of Ca²⁺ ion increased with increasing the molar ratio CaO/SiO₂, reached to a maximum when CaO/SiO₂≅1, and then decreared; no movement was observed when CaO/SiO₂_??_2. Additions of Al₂O₃ and Fe₂O₃ to MgO together with CaO and SiO₂, however, produced different results, i.e., the rate of movement of Ca²⁺ in this mixture increased with increasing the ratio (CaO/SiO₂) without having a maximum.
(2) Additions of oxides such as TiO₂, Cr₂O₃, MnO₂, B₂O₃, etc., which were found, by the author's previous works, to be effective in promoting sintering of MgO and the growth of periclase crystals, always increased the rate of movement of Ca²⁺.
(3) Comparing with Ca²⁺ ions, Fe³⁺ ions in MgO had a low rate of diffusion. Draining occured only when Ca²⁺ coexisted in MgO.
(4) X-ray analysis showed that the compounds, CaO⋅MgO⋅SiO₂, 2CaO⋅Fe₂O₃, 4CaO⋅Al₂O₃⋅Fe₂O₃, etc., were produced in MgO by the movement of Ca²⁺ and Fe³⁺ ions.
(5) It was suggested that when the above compounds melt at high temperatures producing the liquid phase, the loard-bearing capacity of MgO is lowered.

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The decomposition of Na₂ZrO₃, sinterability, mineralogical composition and expansion of sintered body of the Systems Na₂ZrO₃-Al₂O₃ and β Al₂O₃-ZrO₂ were studied. The results obtained are summarized as follows:
(1) The decomposition of Na₂ZrO₃ is promoted by the addition of Al₂O₃ and even at 1000°C Na₂ZrO₃ decomposes. At 1200°C Na₂O produced by the decomposition reacts partially with Al₂O₃ to form β Al₂O₃, but the larger parts of Na₂O vaporize. The amount of Na₂O absorbed as β Al₂O₃ increases up to 1400°C and above the temperature it decreases due to the decomposition of β Al₂O₃. Even at 2000°C, however, β Al₂O₃ still remains without decomposition.
(2) The good sintered body can be obtained with easy by starting the mixture of the system Na₂ZrO₃-Al₂O₃. In the sintered body a Al₂O₃, β Al₂O₃ and ZrO₂ are comfirmed by X-ray analysis.
(3) The liquidus boundary in the region of small amounts of Na₂O seems to exist near the curve joining the points 45% Al₂O₃, 55% ZrO₂ and 3.12% Na₂O, 66.94% Al₂O₃, 29.94% ZrO₂.
(4) In the mixture of β Al₂O₃-ZrO₂ a part of β Al₂O₃ decomposes to produce α Al₂O₃ during heating, but its larger parts remain in the sintered body without decomposition. The expansion of the sintered body is small as shown in Fig. 7 and 8. Its volume change caused by the transformation of ZrO₂ phase remarkably decreases with the addition of β Al₂O₃.

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Preparation of alumino-phosphate glasses containing a few per cent of FeO, which are used as the infra-red shielding glass, are fairly difficult because their light absorption spectrum is liable to be affected delicately by their chemical compositions even when they are prepared under the same melting condition. The author has made a study on the effects of chemical composition on the light absorption characteristics of this type of glasses.
Glasses of the two system, P₂O₅-Al₂O₃-ZnO-R₂O and P₂O₅-Al₂O₃-B₂O₃-R₂O, both containing FeO as the infra-red absorbent, were melted under the reducing condition given by the addition of metallic silicon. For the glasses prepared the absorption measurement was made in the range 0.4 to 2.2μ.
For these glasses two strong absorption bands were almost always observed at about 1.1 and 2.2μ in their absorption spectrum. The glasses containing FeO more than 3.2 mole per cent and R₂O less than 5 mole per cent were found to have a satisfactory infrared shielding power. With increasing the alkali (R₂O) content the infra-red absorption of glass decreased, becomming liable to be affected by the kind of alkali. When the R₂O content reached to 14 mole per cent, with the exception of lithia, the glasses were stained with brown color, showing the anomalous absorption at the shortwave region. The infrared absorption of the glass containing B₂O₃ was little stronger than that of the glass containing ZnO.
The relation between the state of iron in the phosphate glasses and the absorption characteristics was explained by the screening theory proposed by W. A. Weyl.

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The expansion and shrinkage behaviors of ferrites in the temperature ranging from room temperature to 1400°C were observed. The curves given by the dilatometer under conditions of increasing temperature are shown in Fig. 5 through Fig. 14.
It is evident upon examination of the figures that (1) a sudden expansion occurs at a temperature of about 900°C during firing of Zn-ferrite and Cd-ferrite having the normal spinel structure in the resulting specimen, and above this temperature the shrinkage of specimens is found up to 1400°C, (2) the change in the expansion behavior don't occur for samples of Ni-ferrite and Cu-ferrite having inverse spinal structure and also during reheating of the samples Zn-ferrite and Cd-ferrite cooled after firing, (3) the expansion of the mixture of NiO, ZnO and Fe₂O₃ during heating tends to increase with increasing ZnO content.

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The effects of mode of preparation, compacting pressure, additives, poling treatment on the electro-mechanical properties of lead titanate zirconate ceramics modified with partial substitution of Sr for Pb were studied. The results obtained are as follows:
(1) The evaporation of PbO during heating can be prevented considerablly by the treatment of the specimen with high compacting pressure such as 872kg/cm² and the author's firing method mentioned as previous report (This Journal 66, 260, 1958).
(2) The relation between the electro-mechanical coupling coefficient (k) for radial mode vibration and applied time of field was made clear.
(3) Considerable improvements in the temperature dependence of k, frequency constant, specific permittivity and aging characteristics of k were observed in particularly for the specimen containing small amount of CeO₂ additive.

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