摘要
使用Si-25%Zr(质量分数)合金通过液相烧结法在C/SiC复合材料表面制备了SiC-ZrC抗氧化涂层,研究了烧结过程中涂层的相结构演化,并测试了1400℃及空气气氛下材料的抗氧化性能,分析了涂层氧化前后显微结构的变化,以及氧化对C/SiC复合材料弯曲性能的影响。结果表明,Zr元素在涂层中以ZrC相的形式存在,ZrC颗粒的引入细化了反应SiC层的组织,在氧化过程中形成致密连续的SiO2薄膜,并在氧化500 s后试样出现增重,制备了SiC-ZrC抗氧化涂层的C/SiC样品在1000 s的氧化实验后弯曲强度下降低于5%。
Owing to their low density and good mechanical properties at high temperatures, C/SiC composites are increasingly used in the aerospace industry. They are also being proposed as thermalstructural materials in the hypersonic field;however, C/SiC composites are easily oxidized in hightemperature air environments. In this study, a C/SiC composite was coated with a SiC-ZrC oxidationresistant layer by a two-step sintering method using Si-25%Zr(mass fraction) alloy, and the phase evolution of the coating was studied during the sintering. The oxidation resistance of the material was then tested at 1400 ℃ in an air environment. The microstructural changes of the coating before and after oxidation and the effect of oxidation on the bending properties of C/SiC were analyzed. After the reaction with carbon, Si and ZrSi2 disappear in the coating, leaving only pure ZrC and SiC. The ZrC phase refined the structure of the reactive SiC layer. The grain size of the sintered SiC was 2 μm, versus 5-20 μm for SiC sintered from pure Si. The refined grains created a dense and continuous SiO2 film during the oxidation process. As the oxidation time was increased at 1400 ℃, the C/SiC composite with the SiC-ZrC coating began losing weight at 200 s, but began gaining weight at 500 s as a dense SiO2 film was formed. After1000 s of oxidation, the flexural strength of the C/SiC composites was 335 MPa, only 5% lower than that of the initial C/SiC composite. According to this result, the sintered SiC-ZrC oxidation-resistant film effectively protected the mechanical properties of the C/SiC composite during the oxidation process.
作者
皮慧龙
石小磊
徐兴祥
PI Huilong;SHI Xiaolei;XU Xingxiang(State Key Laboratory of Thermostructural Composite Materials,Northwestern Polytechnical University,Xi'an 710072,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第6期791-796,共6页
Acta Metallurgica Sinica
关键词
抗氧化涂层
SiC-ZrC
液相烧结
oxidation resistant coating
SiC-ZrC
liquid-phase sintering
