Fracture toughness of fine ceramics depends on notch root radius, crack length and grain size. The effects of notch root radius on fracture toughness were investigated using gypsum and polymer gypsum composite. The notch root radius were varied in size ranging from 0.1 mm to 1.0 mm. Experiments were conducted at room temperature. The results were discussed based on the process zone size fracture criterion. The relationship between notch root radius and fracture toughness was in good agreement with the theoretical one deduced from the criterion. Polymer gypsum composite was confirmed to be excellent materials showing high fracture toughness and bending strength in compared with gypsum.

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It was investigated improvement in efficiency of manufacturing concrete product and reduction of environmental burden with ultra high early strength additive. The strength necessary for stripping was obtained even in shortening precuring and steam curing time and strength after stripping was increased because hardening with condensation was accelerated with ultra high early strength additive. It was found that even in the case of using ultra high early strength additive and blast furnace slag cement, the strength was more than strength with normal portland cement, which leads to great reduction of environmental burden. Also, high efficiency of manufacturing concrete product and the reduction of possessing mold become possible because it is possible to attain a high use degree efficiency of mold.

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酸化マグネシウム (MgO) 粉体の焼結に及ぼす粒度分布の影響を検討した.試料には一次粒子径 (平均) が107nm (F (107)) および261nm (G (261)) の2種類のMgO粉体を使用した.一次粒子径分布の狭いF (107) 粉体の成形体を昇温加熱すると, 粒子同士の焼結により均質に粒成長が進行したが, 一次粒子径分布の広いG (261) 粉体の成形体を昇温加熱すると微細な粒子と粗大な粒子間で焼結が優先的に進み, 生成した結晶粒同士で焼結がさらに進行した.これらの成形体を1300℃の一定温度で焼成すると, F (107) 焼結体の相対密度はG (261) 焼結体のそれらよりも高い値を示した.また, F (107) 焼結体の場合には焼成時間の増加にともない直線的に結晶粒の成長が起こったが, G (261) 焼結体の場合には20時間以上焼成すると急激に結晶粒の成長が起こり, それにともない気孔が結晶粒内に取り込まれることがわかった.以上の結果から, 一次粒子径分布の広いMgO粉体を出発粉体に使用すると, 焼結中に気孔を結晶粒内に取り込み, 急激な結晶粒の成長を引き起こすため, 緻密化が抑制されやすくなることがわかった.

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Phosphate glass can contain many kinds and amounts of modifier oxides. Chemical durability of the glass is inferior to other oxide glasses, because phosphate glass has nonbridging oxygen, and this causes the limitation of application field of the glass. To improve the defect of the glass, the preparation of phosphate glass containing nitrogen was carried out under usual atmosphere by using cyclo-tri-μ-imido-triphosphate as raw material. According to IR study, it was found that the phosphate glass containing nitrogen as an imino group. The phosphate glass containing sodium was dark brown, and the phosphate glass containing magnesium or calcium was not colored. The solubility of phosphate glass containing nitrogen decreased very much in comparison with phosphate glass without nitrogen.

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In order to achieve mercury-free flat fluorescent lamp, prevention of the sputtering of the electrode and determination of an appropriate sealed gas composition are necessary. In this study, a flat transparent electrode covered with glass layer was applied to a flat fluorescent lamp. The effects of the sealed gas composition, the sealed gas total pressure and the distance between a pair of electrodes were investigated to determine a condition under which the lamp exhibits a similar luminance to that of the corresponding commercial mercury lamp. As a result, an appropriate condition was determined.

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Formation of SnO was examined by the homogeneous precipitation method in which SnCl₂, (NH₂) ₂CPO and halogenide were used. The minimum concentration of the additive on SnO formation depended on the kind of halogenide and the concentration of halogenide became lower in the order chloride, bromide, iodide. The process of SnO formation is via 5SnO.2H₂O or unknown compound as an intermediate in the solution with pH 2-8.

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大気中へ放出された二酸化炭素は温室効果ガスとして作用する.この二酸化炭素を金属酸化物 (あるいは金属水酸化物) と反応させることにより固定する方法を提案した.この方法では金属の炭酸塩が作られるが, これは地球上に多量に産出する物質であり, 保存するにも安全である.金属酸化物の炭酸塩化の反応機構を説明し, これに関する過去の文献を解説した.

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