The bonding mechanism of glass to metal seals was investigated on practical sealing materials. On three sorts of glasses (soda-lime glass, boro-silicate glass, and lead glass) to which various metal oxides were added, thermal expansion and contact angle against metals, as well as adherence strength, were measured.
In soda-lime glass to iron metal seals, the introduction of iron oxide into the glass enhanced the corrosion of the metal surface, lowered the contact angle and strengthened the adherence. The change in the thermal expansion, slight as it was, suggested the loosening of network structure or the increase in “effective” chemical bonding. In these seals, physical or mechanical bonding, as well as chemical bonding, seemed to play an important role.
In boro-silicate glass to iron-nickel-cobalt alloy seals, metal oxides introduced into the glass increased the thermal expansion considerably, lowered the contact angle and strengthened the adherence. As compared with the soda-lime glass to iron metal seals, mechanical bonding was rather weak, whereas chemical bonding became stronger. In practical sealing, bonding through oxide interlayer also seemed to participate in the glass to metal adherence.
In glass to chromium seals, the introduction of metal oxides into the glass raised the contact angle, but had no effect on the adherent strength. Oxide interlayer formed by the reaction between molten glass and metal, seemed to play an important role.
In glass to copper seals, adherence by chemical bonding seemed to be effective, but in practical sealing adherence through oxide interlayer seemed also important.

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As a part of the studies on the sintering behavior of the magnesia prepared by decomposition of magnesium hydroxide, effects of the crystal habits of the hydroxide, and of the additions of iron oxide and silica on the sintering process of magnesia were examined by means of measurements of dilatation and isothermal shrinkage of the specimens.
The crystal habits of the hydroxide, i.e. fibrous and massive, have no effect on the sintering process of magnesia. The addition of iron oxide promotes the sintering of magnesia, while the addition of silica rather retards the sintering, except the case when the amounts as small as 0.3% SiO₂ is added, which accelerates the sintering a little. The isothermal shrinkage of the specimens of Mg(OH)₂ and of the specimens consisting of Mg(OH)₂ and Fe₂O₃ or small amounts of SiO₂ are all represented by the general formula (ΔL/L₀)^p=B″t, which means that the sintering of these specimens is the process controlled with the diffusion mechanism. The experimental activation energy of the diffusion sintering for the specimens of the magnesium hydroxide was 47-57kcal/mole, which is considerably lower than those of the processes controlled by the similar diffusion mechanism. These low activation energy might be due to the fact that the magnesia used for these measurements were prepared by the decomposition of hydroxide at temperature as low as about 500°C, so that it contains many defects in the lattice. The addition of 0.3% Fe₂O₃ decreases the activation energy and the frequency factors for the sintering, but, on the contrary, the further addition of it increases both of these values. The addition of 0.3% SiO₂ also decreases these values. The acceleration of the sintering of MgO by the additions of Fe₂O₃ and a small amount of SiO₂ is due to the reduction of the experimental activation energy. For the over-all sintering of the specimens, the frequency factors as well as the activation energy must be taken into consideration.

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Sintering and crystallization processes of the glass powder of various particle sizes with cordierite composition have been investigated by means of thermal shrinkage measurement, D. T. A., X-ray diffraction and polarized microscopic observation.
The results obtained are summarized as follows:
1) Viscous flow mechanism was applicable for the sintering of the glass powder that initiated at 820°-920°C, whereas plastic flow mechanism became to be available in the final stage of sintering where μ-cordierite began to crystallize from the glass phase at 900°-980°C. Sintering measured by thermal shrinkage of the compact body ceased at 950°-1000°C owing to the almost complete crystallization at the periphery of individual particles. Thereafter, μ-cordierite transformed to α-form at 970°-1070°C, and the microstructure of sintered bodies was unchanged up to 1300°C.
2) As shown above, there existed ranges for the temperatures where sintering, crystallization and phase transformation started, since the initiation of the phenomena was affected by the particle size and the heating rate. The smaller particle size and the faster heating rate resulted in the larger thermal shrinkage and the denser sintered body. Accordingly, physical properties of the sintered body can be controlled to a considerable wide range.
Activation energies for the sintering of glass powder by viscous flow, the crystallization of μ-cordierite and the transformation to α-form obtained by the Arrhenius plot were 36-115 (920°-855°C), 86, and 60kcal/mole respectively, and enthalpy changes estimated for the crystallization of μ-cordierite and the transformation were found to be 16 and 18kcal/mole respectively.

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斜方晶γBaCO₃を加熱すると六方晶α-BaCO₃に, 続いて立方晶β-BaCO₃に転移する. γ-BaCO₃に少量のCr₂O₃を添加して (図-3) γ-α転移温度付近で加熱することによって生成する未発表の結晶 (γ'相と仮称) について実験を行なった. γ'相の生成条件はγ-αの転移温度付近 (図-1) で酸化性雰囲気で加熱することであり, 得られたγ'相 (図-4) は再加熱, 乳鉢中での数分間の摩砕あるいは水中に浸漬 (図-5) することにより, 容易にγ-BaCO₃に転相するという極めて興味のある変化を示す準安定相である.

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