Investigation of the Thermal Radiation Properties of C/SiC Composites
|School||Northwestern Polytechnical University|
|Keywords||C / SiC composites Heat radiation performance SiC coating Heat treatment High-temperature oxidation|
In the field of aerospace and weaponry , the C / SiC ceramic matrix composite thermal structure density, good erosion resistance , low production cost, simple structure and better than the C / C composite oxidation resistance and a series of excellent performance. C / SiC composite heat radiation performance of the key parameters of the use of important reference data and the thermal protection design , it will greatly affect the C / SiC the thermal structural components work performance and its service life . This paper systematically studied the surface characteristics , the impact of the coating thickness, heat treatment and high temperature oxidation 2D and 3D CVI-C/SiC of composite thermal radiation properties . The main contents and results are as follows : (1) fiber preform woven C / SiC composites thermal radiation properties . The results show that : 3D C / SiC composite heat radiation performance is superior to 2D C / SiC , both hemispheres , respectively, 0.82 and 0.78 to the total emissivity in the infrared band 2.5μm ~ 25μm range of 2D C / SiC 3D C / SiC composites is always higher than the normal spectral reflectance . (2) of the SiC coating thickness of the C / SiC composites thermal radiation properties . With the SiC coating thickness increases , the total emittance of 2D and 3D C / SiC composites are first reduced and then increased , but also the the total emittance gap gradually decreases ; when the coating thickness of 70 , 2D and 3D C / SiC the worst heat radiation performance of the composite material , both the total emission rate of only 0.45 and 0.53 , respectively , 2D and 3D C / SiC of the heat radiation performance is best when the thickness of the coating increased to 140μm , the total of the two emission rates were 0.82 and 0.83 . (3) study the surface characteristics of the C / SiC composite heat radiation performance . After found SiC-C/SiC polishing the surface roughness was significantly reduced , and enhance the reflective properties of the C / SiC composite material , so that the total transmission rate was significantly reduced . (4 ) Vacuum 1600 ° C for 1h after heat treatment , uncoated C / SiC , the total transmission rate decreased ; SiC-C/SiC polishing SiC-C/SiC , hemisphere to the total emission rate increased significantly . ( 5 ) Atmospheric Environment 1300 ° C , oxidation treatment after 5h , the uncoated C / SiC , SiC-C/SiC polishing SiC-C/SiC of varying degrees of oxidation , the material surface has a SiO 2 < / sub> oxide film formation. The total emittance of the three surface features of C / SiC composites have all increased.