Mass Transfer Mechanism in Yb2Si2O7 Under Oxygen Potential Gradients at High Temperatures
Mass Transfer Mechanism in Yb2Si2O7 Under Oxygen Potential Gradients at High Temperatures
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DOI：
10.1002/9781119407270.ch19
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发表时间：
2017-07
期刊：
影响因子：
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通讯作者：
S. Kitaoka;Tsuneaki Matsudaira;M. Wada;N. Kawashima;Daisaku Yokoe;T. Kato;M. Takata
中科院分区：
文献类型：
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作者：
S. Kitaoka;Tsuneaki Matsudaira;M. Wada;N. Kawashima;Daisaku Yokoe;T. Kato;M. Takata
研究了厚达几百微米的多晶Yb2Si2O7硅片在高温下陡峭氧势梯度(d)下的氧渗透性。这些dO是通过将硅片的上下表面暴露在不同氧分压（PO2）的大气中产生的。所得数据与莫来石和Al2O3的文献数据进行了比较。发现Yb2Si2O7的氧渗透受氧从高PO2表面向低PO2表面的晶界（GB）扩散控制，同时镱的晶界向相反方向扩散。与GB扩散引起的氧渗透相比，硅的GB扩散引起的氧渗透可以忽略不计。氧和单阳离子的同步GB扩散过程没有由于相互扩散而加速或抑制，可以用Gibbs-Duhem方程来描述，莫来石和Al2O3的数据也是如此。用GB密度归一化后，Yb2Si2O7的氧透性常数明显大于莫来石和Al2O3。
The oxygen permeability of polycrystalline Yb2Si2O7 wafers having a thickness of several hundred microns and serving as model environmental barrier coating (EBC) layers were evaluated under steep oxygen potential gradients (d) at high temperatures. These dO were produced by exposing the upper and lower surfaces of wafers to atmospheres with different oxygen partial pressures (PO2). The resulting data were compared with literature data for mullite and Al2O3. It was found that the oxygen permeation of Yb2Si2O7 is controlled by grain boundary (GB) diffusion of oxygen from the high PO2 surface to the low PO2 surface, with simultaneous GB diffusion of ytterbium in the opposite direction. Oxygen permeation associated with the GB diffusion of silicon was negligibly small compared to that generated by ytterbium GB diffusion. The concurrent GB diffusion of oxygen and single cations proceeds without acceleration or inhibition due to interdiffusion, and can be described by the Gibbs-Duhem equation, as can the mullite and Al2O3 data. The oxygen permeability constant for Yb2Si2O7, normalized by the GB density, was significantly larger than those for mullite and Al2O3.