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首页> 外文期刊>日本セラミックス協会学術論文誌 >Effect of HfO_2 Addition on Sintering of Si_3N_4
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Effect of HfO_2 Addition on Sintering of Si_3N_4

机译：HfO_2添加对Si_3N_4烧结的影响

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摘要

The effect of HfO_2 addition on sintering of Si_3N_4-Y_2O_3-AIN system was investigated. Although the densification was improved by the addition of HfO_2, the behavior was divided into two types according to the selected firing temperature: below 1800 deg C, the maximum density was achieved with 1.5 mass percent HfO_2 addition; on the other hand, above 1800 deg C density continuously increased with increasing HfO_2 addition. This densification behavior could be explained according to phase diagrams of the HfO_2-Y_2O_3 centre dot SiO_2 (eutectic temperature: 1800 deg C) and HfO_2-Y_2O_3 centre dot2SiO_2 (eutectic temperature: 1600 deg C). As a tentative mechanism for densification, it was considered that, in the initial stage of sintering, the formation of some liquid phases with low melting point promoted densification. Then precipitation of c-HfO_2 including Y, Si elements and of HfN including O occurred. This mechanism was supported by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive spectrometry (EDS) analysis. The phase transformation from #alpha#-Si_3N_4 to #beta#-SiAlON was found to be enhanced by HfO_2 addition. Consequently, sintered bodies obtained from the Si_3N_4-Y_2O_3-AIN-HfO_2 mixtures were consisted of not only elongated #beta#-SiAlON grains, and grain-boundary phases composed of Hf, Si, Al, Y and O, but also isolated spherical grains of both c-HfO_2 and HfN (200-400 nm in diameter).
机译：研究了HfO_2添加对Si_3N_4-Y_2O_3-AIN体系烧结的影响。尽管通过添加HfO_2可以改善致密性，但根据所选的烧成温度，该行为可分为两种类型：在1800℃以下，通过添加1.5质量％的HfO_2可获得最大密度;在1800℃以下可获得最大密度。另一方面，高于1800摄氏度时，随着HfO_2添加量的增加，密度连续增加。该致密化行为可以根据HfO_2-Y_2O_3中心点SiO_2（共晶温度：1800℃）和HfO_2-Y_2O_3中心点2SiO_2（共晶温度：1600℃）的相图进行说明。作为致密化的初步机制，认为在烧结的初始阶段，一些低熔点液相的形成促进了致密化。然后发生包括Y，Si元素的c-HfO_2和包括O的HfN的沉淀。 X射线衍射（XRD），透射电子显微镜（TEM）和能量分散光谱（EDS）分析支持了该机制。发现通过添加HfO_2可以增强从＃alpha＃-Si_3N_4到＃beta＃-SiAlON的相变。因此，从Si_3N_4-Y_2O_3-AIN-HfO_2混合物获得的烧结体不仅由细长的＃beta＃-SiAlON晶粒和由Hf，Si，Al，Y和O组成的晶界相组成，而且还由孤立的球形晶粒组成c-HfO_2和HfN（直径200-400 nm）。

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