感光オパールガラスの機械的強度の研究

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When a lithium containing photosensitive glass is exposed to ultraviolet light and then subjected to the heat treatment, it changes into a polycrystalline material characterized by its good mechanical properties (S. D. Stookey. Ind. Eng. Chem., 45, 115 (1953)).The purpose of this paper is to present the relation between the mechanical strength and the grain size of the constituent crystallites of the resultant material.Glass specimens (2.5×5×50mm) of the oxide composition SiO2 81, Li2O 12.5, K2O 2.5, Al2O3 4, CeO2 0.03, Au 0.027% (wt.) were exposed to ultraviolet light by placing them at a distance of 10cm from a 500 watt high pressure mercury lamp for 2 to 1000 min. After the exposure they were heated at three steps; first at 510°C for 30 min. to cause formation of gold nuclei, then at 620°C for 60 min. to cause crystallization of lithium metasilicate partially (40%) from the base glass, and finally at 900°C for 60 min. to convert almost the whole of the base glass to polycrystalline materials consisted of lithium disilicate and β-quartz. The grain size of the constituent crystallites of the resultant material was able to be varied from 0.85 to 2.3μ by changing the U. V. exposure time (Ref. M. Tashiro and S. Sakka. J. Ceram. Assoc. Japan, 67, 263 (1959)).Tests for bending strength and Vickers hardness were made with two classes of specimens, one which completed a whole course of the above heat treatments and the other which completed only the first half of the heat treatments, i.e., heated only up to 620°C.The tests have shown that, for the specimens which completed the whole course of the heat treatments, crystallization increases mechanical strength of the specimens, and the relation between the average grain size of the constituent crystallites (d) and the mechanical properties (M) (both of the bending strength and Vickers hardness) is given by the equation, M=const⋅d1/2.For the specimens heated up to 620°C, partial crystallization of the glass phase was found to increase the mechanical strength of the specimens but in somewhat more complex way. This was attributed to the effects of glass phase still remaining in considerable amounts (60%) in the specimens.
社団法人日本セラミックス協会の論文
1960-06-01

感光オパールガラスの機械的強度の研究

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