Yttrium silicate coatings for SiC coated C/C composites prepared by atmospheric plasma spraying

Different yttrium silicate coatings for SiC-coated C/C composites were designed and prepared by an atmospheric plasma spray method to prevent the C/C composites from oxidation.XRD profiles showed that the coating was composed of Y2SiO5,Y2Si2O7,and Y4Si3O12.SEM showed that the gradient SiC/Y4Si3O12/Y2Si2O7/Y2SiO5 coating had a more compact surface than the other coatings did.Isothermal oxidation tests at 1 500 ℃ in air showed that the weight loss curves of the as-prepared C/C composites showed a linear tendency with time and the weight loss rate of all coated samples increased significantly after 73 h.The coating could protect the C/C composites from oxidation at 1 500 ℃ for 73 h in air with a weight loss rate of 1.01×10-4 g·cm-2·h-1.The SiC/Y4Si3O12/Y2Si2O7/Y2SiO5 was the better coating at high temperature than other coatings.