INFLUENCE OF ATMOSPHERE ON THE FINAL-STAGE SINTERING KINETICS OF ULTRA-HIGH-PURITY ALUMINA
INFLUENCE OF ATMOSPHERE ON THE FINAL-STAGE SINTERING KINETICS OF ULTRA-HIGH-PURITY ALUMINA
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DOI：
10.1111/j.1151-2916.1993.tb07761.x
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发表时间：
1993-09-01
影响因子：
3.9
通讯作者：
HARMER, MP
中科院分区：
文献类型：
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作者：
THOMPSON, AM;HARMER, MP
研究了烧结气氛对超高纯氧化铝终烧过程的影响。模型的最终阶段微结构是通过乳胶球浸渍和烧毁技术定制的。进行了关键实验，定量考察了氧分压对烧结动力学的影响。样品在1850℃的干氢(p(O2)，几乎等于3×10(-17)atm)或湿氢p(O2)几乎等于5×10(-10)到2×10(-11)atm的气氛中烧结，并对其微观结构进行了表征。在干氢中烧结降低了最终组织的气孔/晶界断裂敏感性。在动力学分析中，考虑了每粒气孔数N(G)的变化。结果表明，两种气氛下的致密化速度均受晶界扩散控制，干氢烧结使致密化速度提高了2.25倍。此外，还确定了两种气氛下的晶粒生长速率均由气孔周围物质的表面扩散速率控制，在干氢气氛中烧结可使晶粒长大速率提高5.6倍。干氢气氛的总体效果是，对于给定的颗粒尺寸，它将粗化速率相对于致密化速率提高了2.5倍，从而使颗粒尺寸-密度轨迹向低得多的密度方向移动。
The influence of sintering atmosphere on the final-stage sintering of ultra-high-purity alumina has been investigated. Model final-stage microstructures were tailored via a latex sphere impregnation and burnout technique. Critical experiments have been conducted to quantitatively examine the influence of the oxygen partial pressure on the final-stage sintering kinetics. Samples were sintered at 1850-degrees-C in either dry hydrogen (p(O2), almost-equal-to 3 x 10(-17) atm) or wet hydrogen p(O2) almost-equal-to 5 x 10(-10) to 2 x 10(-11) atm), and their microstructures were characterized as a function of sintering time. Sintering in dry hydrogen decreased the susceptibility of the final-stage microstructure to pore/boundary breakaway. In the kinetic analysis, the variation in the number of pores per grain, N(g), was taken into account. It was found that in both atmospheres, the densification rate was controlled by grain boundary diffusion, and that sintering in dry hydrogen increased the densification rate by a factor of 2.25. In addition, it was determined that the grain growth rate in both atmospheres was controlled by the rate of surface diffusion of matter around the pores and that sintering in dry hydrogen enhanced the grain growth rate by a factor of 5.6. The overall effect of the dry hydrogen atmosphere was that it enhanced the coarsening rate relative to the densification rate by a factor of 2.5, and consequently shifted the grain size-density trajectory to much lower densities for a given grain size.