C/C-SiC复合材料表面ZrB_2基陶瓷涂层的制备及高温烧结机理

Preparation and High-temperature Sintering Mechanism of ZrB_2 Ceramic Composite Coatings for C/C-SiC Composites

采用刷涂-烧结法,分别在C/C-SiC复合材料和C/C复合材料表面制备了ZrB2基陶瓷复合涂层。利用EDS,SEM分析陶瓷涂层的成分及微观形貌,通过对比C/C-SiC基体和C/C基体的表面涂层,对C/C-SiC基体表面涂层的高温烧结机理进行了探究。结果表明:高温下C/C-SiC基体中的硅组元会溢出,造成样品质量损失;同时,溢出的硅组元能渗入到陶瓷涂层中,形成了以硅为主要黏结相,ZrB2等陶瓷相弥散分布的陶瓷涂层;与C/C基体相比,硅组元的溢出能有效促进涂层与基体之间的界面结合。在对基体进行预处理的基础上,采用低温真空脱胶,高温常压烧结,能够制备出结构致密、无裂纹并与基体结合牢固的ZrB2基陶瓷涂层。

The anti-oxidation ZrB2 ceramic composite coatings were prepared on C/C-SiC composites and C/C composites by means of slurry painting. The compositions and microstructures of the com- posites were examined by EDS analysis and SEM. The high-temperature sintering mechanism of ZrB2 ceramic composite coatings was discussed by comparing coating on C/C-SiC composites and C/C com- posites. The results show that silicon overflows from the C/C-SiC matrix during the sintering, which causes the mass loss of samples at high temperature. The silicon coming from matrix penetrates into ceramic coating, in which ZrB2 phase is dispersive distribution and silicon acts as the main binding phase. Silicon effectively promotes the combination of interface between coating and matrix. Based on the pretreatment of substrates and the method of low-temperature vacuum degumming and ordinary pressure sinter, a flawless ZrB2 ceramic composite coating is prepared, which has compact structure and tightly bounds with matrix.