Fabrication and oxidation resistance of mullite/yttrium silicate multilayer coatings on C/SiC composites

作     者：Qingsong MA Lihui CAI 

作者机构：Science and Technology on Advanced Ceramic Fibers&Composites LaboratoryNational University of Defense TechnologyChangsha 410073China 

出 版 物：《Journal of Advanced Ceramics》 (先进陶瓷（英文）)

年 卷 期：2017年第6卷第4期

页      面：360-367页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：the financial supports from the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province and the Science Innovation Foundation of Shanghai Academy of Spaceflight Technology(No.SAST2015043) 

主　　题：oxidation resistance thermal shock resistance coatings mullite yttrium silicate C/SiC composites 

摘      要：A tri-layer coating of mullite/Y_(2)Si_(2)O_(7)/(70wt%Y_(2)Si_(2)O_(7)+30wt%Y_(2)SiO_(5))was prepared on carbon fiber reinforced silicon carbide(C/SiC)composite substrate through dip-coating route for the sake of improving oxidation resistance of C/SiC *** Al_(2)O_(3)-SiO_(2) sol with high solid content was selected as raw material for mullite,and a slurry of Y_(2)O_(3) powder filled silicone resin was used to synthesize yttrium *** microstructure,phase composition,and oxidation resistance of the coating were *** as-fabricated coating shows high density and favorable bonding to C/SiC *** oxidation at 1400 and 1500℃for 30 min under static air,the flexural strengths of coated C/SiC composite were both increased by~30%.The desirable thermal stability and the further densification are responsible for excellent oxidation *** the additional help of compatible thermal expansion coefficients among substrate and sub-layers in coating,the coated composite retained 111.2%of original flexural strength after 12 times of thermal shock in air from 1400℃ to room *** carbothermal reaction at 1600℃ between free carbon in C/SiC substrate and rich SiO_(2) in mullite resulted in severe frothing and desquamation of coating and obvious degradation in oxidation resistance.