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首页> 外文期刊>Journal of the European Ceramic Society >Effects of Y_2O_3 additives and powder purity on the densification and grain boundary composition of Al_2O_3/SiC nanocomposites
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Effects of Y_2O_3 additives and powder purity on the densification and grain boundary composition of Al_2O_3/SiC nanocomposites

机译：Y_2O_3添加剂和粉末纯度对Al_2O_3 / SiC纳米复合材料致密化和晶界组成的影响。

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Sub-micron sized SiC additions can be used to increase the wear resistance and change the fracture mode of Al_2O_3. However, these additions also restrict sintering. A1_2O_3 and Al_2O_3-5 percent SiC 'nanocomposites' were prepared from alumina powders of high purity and of commercial-purity, with or without the addition of Y_2O_3. The effects of these compositional variables on sintering rate, final density and grain boundary composition were investigated. A direct comparison with Al_2O_3-SiO_2 composites was also made, as it has been proposed that SiC partially oxidises during processing of Al_2O_3-SiC nanocomposites. The addition of 5 vol. percent SiC to Al_2O_3 hindered densification, as did addition of 0.15 wt. percent Y_2O_3 or 0.1 wt. percent SiO_2. In contrast, the addition of 0.15 wt. percent Y_2O_3 to Al_2O_3-5 percent SiC nanocomposites improved densification. The composition of A1_2O_3-A1_2O_3 grain boundaries in these materials was studied using STEM and EDX microanalysis. The addition of SiC and SiO_2 caused segregation of Si, and Y_2O_3 addition caused segregation of Y. The segregation of each element was equivalent to <10 percent of a monolayer at the grain boundary. However, if SiC and Y_2O_3 were simultaneously added the segregation increased to 40 percent of a monolayer. The enhanced segregation was attributed to increased oxidation of SiC in the presence of Y_2O_3 allowing formation of a SiO_2-Al_2O_3-Y_2O_3 eutectic phase or a segregated layer which may explain the improvement in sintering rate when Y_2O_3 was added to nanocomposites.
机译：可以使用亚微米级的SiC添加剂来提高耐磨性并改变Al_2O_3的断裂模式。但是，这些添加也限制了烧结。由高纯度和商业纯度的氧化铝粉末（添加或不添加Y_2O_3）制备Al_2O_3和Al_2O_3-5％SiC“纳米复合材料”。研究了这些组成变量对烧结速率，最终密度和晶界组成的影响。还直接与Al_2O_3-SiO_2复合材料进行了比较，因为有人提出SiC在Al_2O_3-SiC纳米复合材料的加工过程中会部分氧化。 5卷。向Al_2O_3中添加5％的SiC阻碍了致密化，添加0.15 wt。 Y_2O_3百分比或0.1 wt。 SiO_2百分比。相反，添加0.15重量％。 Y_2O_3到Al_2O_3-5％的SiC纳米复合材料改善了致密性。利用STEM和EDX显微分析研究了这些材料中Al_2O_3-3-Al_2_2_O_3的晶界组成。 SiC和SiO_2的添加导致Si的偏析，Y_2O_3的添加导致Y的偏析。每个元素的偏析均等于晶界处单层的<10％。但是，如果同时添加SiC和Y_2O_3，则偏析会增加到单层的40％。偏析的增强归因于在Y_2O_3存在下SiC的氧化增加，从而形成SiO_2-Al_2O_3-Y_2O_3共晶相或偏析层，这可以解释当将Y_2O_3添加到纳米复合材料中时烧结速率的改善。

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