窒化ケイ素添加シリカ粉末の焼結から製造された気泡含有シリカガラス

概要

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Bubble-containing silica glasses were fabricated by sintering amorphous silica powders with small amount of silicon nitride powders. Sintering was performed at 1800℃ in N_2 gas atmosphere. It was found that the addition of Si_3N_4 is effective for forming bubbles. By controlling the Si_3N_4 content, various types of bubble-containing silica glasses, such as the so-called the opaque silica galss and the foamed silica glass, could be obtained. Addition of 0.004 mol% Si_3N_4 produced highly opaque silica glasses containing a large number of small bubbles, while 0.431 mol% Si_3N_4 resulted in low-density foamed silica glasses containing large 1 mm-sized bubbles. Wide variations of bubble size and density were observed on these glasses. Thermal conductivities were estimated and compared with several literature values. The relation between thermal conductivity and bubble density was discussed based on a model simulation.
2000-10-01