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DEVELOPMENT OF HIGH PERFORMANCE SILICON NITRIDE CERAMICS COATED WITH MULLITE

高性能莫来石涂层氮化硅陶瓷的研制

基本信息

批准号：
05555237
负责人：
HATTORI Makoto
金额：
$ 4.67万
依托单位：
YONAGO NATIONAL COLLEGE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05555237/
关键词：
CERAMICS GRADIENT INTERFACE SURFACE MODIFICATION AUTOCLAVE NON-OXIDE CORROSION RESISTANCE STRUCTURAL MATERIAL COMPOSITE

项目摘要

It is well known that Si_3N_4 ceramics are readily susceptible to high-temperature oxidation and hydrothermal corrosion. Mullite and Si_3N_4 have very close coefficients of thermal expansion, suggesting a durable coating/substrate system can be made. In general, mullite shows better corrosion resistance to high-temperature oxidation and hydrothermal corrosion. The purpose of this project is to fabricate mullite coated Si_3N_4 ceramics and to characterize the oxide/nitride gradient nano-interface of the materials. Mullite coatings by using the hydrolysis of mixed alkoxides were applied to Si_3N_4 coupons and hydrothermally corroded Si_3N_4 coupons. The following resuls were obtained.1.X-ray diffraction indicated mullite powders to be a single phase, which were prepared by the hydrolysis of mixed alkoxides route and heated at above 900ﾟC.2.Mullite coatings on Si_3N_4 substrates can be successfully made by dipping in the mixed alkoxides solution. Coatings were approximately 30 to 80 mum thick on Si_3N_4 substrates after heating at 1300ﾟC.These materials have a oxide/nitride gradient interface at coating/substrate system.3.Coatings showed good adherence to the Si_3N_4 substrates, but poor density. Because of these features, the fracture strength and vickers hardness were relatively low compared to Si_3N_4 ceramics.

众所周知，Si_3N_4陶瓷易受高温氧化和水热腐蚀的影响。莫来石和Si_3N_4具有非常接近的热膨胀系数，表明可以制备耐久的涂层/基体系统。一般来说，莫来石对高温氧化和水热腐蚀表现出更好的耐腐蚀性。本课题的目的是制备莫来石包覆Si_3N_4陶瓷，并对材料的氧化物/氮化物梯度纳米界面进行表征。采用混合醇盐水解法在Si_3N_4试样和水热腐蚀后的Si_3N_4试样上制备莫来石涂层。结果表明：（1）采用混合醇盐水解法制备的莫来石粉末经900 ℃以上热处理后，X射线衍射分析表明为单相莫来石粉末;（2）采用浸渍法在Si_3N_4基体上成功地制备了莫来石涂层。在1300 ° C加热后，Si_3N_4基底上的涂层厚度约为30至80 μ m。这些材料在涂层/基底系统中具有氧化物/氮化物梯度界面。3.涂层与Si_3N_4基底具有良好的粘附性，但密度较差。与Si_3N_4陶瓷相比，其断裂强度和维氏硬度较低。