利用表面形成Si_2N_2O层提高Si_3N_4陶瓷材料抗氧化性能

AN IMPROVEMENT ON OXIDATION-RESISTANCE PROPERTY OF Si_3N_4 CERAMICS BY FORMING A Si_2N_2O SURFACE LAYER

根据对Ｓｉ－Ｎ－Ｏ系统相图的分析，首次在Ｓｉ３Ｎ４陶瓷材料表面形成Ｓｉ２Ｎ２Ｏ抗氧化层。其方法是利用Ｓｏｌ－Ｇｅｌ在Ｓｉ３Ｎ４陶瓷的表面涂上一层ＳｉＯ２（其中含有１０％的Ａｉ２Ｏ３）涂层后，在Ｎ２气氛中，并有Ｓｉ３Ｎ４粉末和ＳｉＯ２粉末存在的条件下，于１２７３～１６７３Ｋ的温度下进行热处理。用ＸＲＤ和ＸＰＳ分析验证了Ｓｉ２Ｎ２Ｏ（和／或Ｏ’－Ｓｉａｌｏｎ）层的存在。由于形成了Ｓｉ２Ｎ２Ｏ（和／或Ｏ’－Ｓｉａｌｏｎ）层，Ｓｉ３Ｎ４陶瓷材料在１５７３Ｋ的温度下氧化１００ｈ后，氧化增量从原来的０．４２ｍｇ／ｃｍ２降低到０．２４ｍｇ／ｃｍ２。

Based on the analysis of phase diagram of the Si-N-O system,a surface antioxidation layer of Si2N2O on the Si3N4 ceramics was firstly formed.The approach is that the Si3N4 ceramics surface is coated with a silica layer(including 10% Al2O3) using Sol-Gel method, and then heat-treated in the presence of St3N4 and SiO2 POwders under N2 atmosphere at 1273￣1673 K. The existence of the Si3N2O(and /or O'-Sialon)layer has been confirmed by both XRD and XPS analyses. The formation o f the surface layer of Si2N2O (and/or O'-Sialon) significantly decreases the oxidation weight-gnining of Si3N4 ceramics in 100h at 1573 K from 0. 42 mg/cm2 to 0. 24 mg/cm2.