Preparation of SiC transition layer on the surface of C/SiC composite by pack cementation and its properties
[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 Al2O3 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 5.531 μm.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.
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