C/SiC复合材料表面SiC过渡层的包埋法制备与性能

Preparation of SiC transition layer on the surface of C/SiC composite by pack cementation and its properties

[目的]碳/碳化硅(C/SiC)复合材料是航空航天领域最有发展前景的高温热防护结构材料之一,但其表面由于制备过程中化学气相渗透而造成粗糙度低、与涂层间结合强度差的问题有待解决。[方法]以Si粉、C粉和少量Al_(2)O_(3)粉为原料,通过包埋法在C/SiC基体表面制备了SiC涂层。[结果]该涂层与基体之间具有较好的化学亲和性,热膨胀系数匹配度高,表面状态改善情况好。SiC涂层的表面粗糙度(Ra)相较于C/SiC基体实现了从1.732μm到5.531μm超2倍的提升,且涂层与基体结合良好,平均抗拉结合强度达到了4.946 MPa。[结论]该方法处理后的C/SiC复合材料满足了后续制备功能化涂层的要求。

[Introduction]C/SiC composites are known as one of the most promising high-temperature materials for thermal protection systems in aerospace industry.However,the problems of low surface roughness of C/SiC composite and poor adhesion strength of coating on C/SiC composite due to chemical vapor infiltration during the preparation of C/SiC composite need to be solved.[Method]A SiC coating was prepared on the surface of C/SiC substrate by pack cementation(PC)with Si particles,C particles,a small amount of Al_(2)O_(3) particles.[Result]The SiC coating had good chemical affinity with the substrate,high matching coefficient of thermal expansion,and good improvement in surface properties of C/SiC substrate.Compared with the C/SiC substrate,the surface roughness(Ra)of the PC-SiC coating was increased by more than two times from 1.732 to 5.531μm.The SiC coating was well adhered to the C/SiC substrate with an average tensile adhesion strength of 4.946 MPa.[Conclusion]The PC-SiC coating can be used as a transition layer for preparation of functional coatings on C/SiC composites.