溶融急冷法による高密度熱収縮酸化物の作製

概要

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By rapid quenching of ZrW_2O_8 melt from 1300℃, dense specimens with few inner pores were successfully prepared. Dilatometry experiments were performed and an abrupt thermal expansion was observed in the range 120-160℃. probably due to removal of internal stress upon the first heating measurement from room temperature to 300℃. The specimen annealed at 200℃ for removal of internal stress exhibited a negative average thermal expansion coefficient of -(4-5) × 10^<-6> K^<-1> from room temperature to 250℃, which was smaller than that of sintered ceramic ZrW_2O_8, (-(6-10) × 10^<-6>K^<-1>). X-ray diffraction and secondary electron microscopy measurements revealed that the obtained specimen was a hybrid of ZrO_2 and/or WO_3 grains with 〜1μm diameter and ZrW_2O_8 grains with 10-25 μm diameter. The smaller negative thermal expansion could be attributed to this hybridization due to decomposition of ZrW_2O_8 during the quenching process.
2002-06-01