Preparation of dense negative-thermal-expansion oxide by rapid quenching of ZrW2O8 melt
Preparation of dense negative-thermal-expansion oxide by rapid quenching of ZrW2O8 melt
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DOI：
10.2109/jcersj.110.544
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发表时间：
2002-06-01
影响因子：
1.1
通讯作者：
Hashimoto, T
中科院分区：
文献类型：
--
作者：
Morito, Y;Wang, SR;Hashimoto, T
通过对ZrW_2O_8熔体在1300 ℃的快速淬火，成功地制备了内部气孔少、致密的试样。进行了膨胀实验，在120- 160 ℃范围内观察到突然的热膨胀，这可能是由于从室温到300 ℃的第一次加热测量时消除了内应力。在200 ℃退火消除内应力的试样从室温到250 ℃的平均热膨胀系数为负的-（4-5）× 10（-6）K-1，小于烧结陶瓷ZrW_2 O_8的平均热膨胀系数（-（6-10）× 10（-6）; K-1）。X射线衍射和二次电子显微镜测量表明，所获得的样品是一个混合的ZrO 2和/或WO 3颗粒与类似的1 μ m直径和ZrW 2 O 8颗粒与10-25 μ m直径。较小的负热膨胀可以归因于这种杂化由于ZrW 2 O 6在淬火过程中的分解。
By rapid quenching of ZrW2O8 melt from 1300degreesC, dense specimens with few inner pores were successfully prepared. Dilatometry experiments were performed and an abrupt thermal expansion was observed in the range 120-160degreesC, probably due to removal of internal stress upon the first heating measurement from room temperature to 300degreesC. The specimen annealed at 200degreesC for removal of internal stress exhibited a negative average thermal expansion coefficient of -(4-5) x 10(-6) K-1 from room temperature to 250degreesC, which was smaller than that of sintered ceramic ZrW2O8, (-(6-10) x 10(-6); K-1). X-ray diffraction and secondary electron microscopy measurements revealed that the obtained specimen was a hybrid of ZrO2 and/or WO3 grains with similar to1 mum diameter and ZrW2O8 grains with 10-25 mum diameter. The smaller negative thermal expansion could be attributed to this hybridization due to decomposition of ZrW2O6 during the quenching process.