Si–Mo–Cr coating for C/SiC coated carbon/carbon composites against oxidation

Abstract

Si-Mo-Cr oxidation protective coating has been prepared on the surface of C/SiC coated carbon/ carbon (C/C) composites by pack cementation technique. The phase composition and microstructure of the as prepared coatings were characterised by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersion spectrum (EDS) analyses. The oxidation behaviour of the coated C/C specimens was also investigated at 1500uC in air. The results show that the as prepared coating is mainly composed of SiC, MoSi 2 , CrSi 2 and Si. The coating characterised by excellent oxidation resistance and thermal shock resistance can effectively protect C/C composites from oxidation for 186 h at 1500uC in air and endure the thermal cycle between 1500uC and room temperature for nine times, while the corresponding weight loss is only 0?33%. The excellent oxidation protection ability of the coating is primarily attributed to the formation of a compound glass layer, including SiO 2 and Cr 2 O 3 .

Resistance of different Zn coatings at elevated temperature air environments

“…A promising technique that could be used alternatively is chemical vapour deposition by pack cementation. [2][3][4][5][6][7][8] With this method, the formation of zinc diffusion coatings is accomplished by heating the substrate up to 400uC together with a mixture of powders containing zinc and a halide activator. Another commonly used method is combustion thermal spray.…”