SiC/Si-MoSi2 oxidation protective coatings for carbon materials

In order to improve the oxidation resistance of carbon material, a SiC/Si-MoSi2, oxidation protective coating was prepared on graphite substrate. The graphite substrate was firstly infiltrated with silicon in vacuum atmosphere to obtain 220 mu m thickness SiC inner layer, and 80 mu m thickness Si-MoSi2 outer layer was made by using a Si-Mo slurry. The effect of Mo/Si of slurry and SiC inner layer on the oxidation resistance of coating was studied. Results indicated that the as-received coating with the Mo/Si of 40% in the slurry has excellent oxidation protection for long life at 1673 K in air. The SiC inner layer acts as a barrier to prevent the infiltration of liquid Si into the pores of the graphite substrate during the sintering of the outer layer and is beneficial to maintain the Mo/Si of 40% in the slurry. The improvement of coating properties can be attributed to the well-coating microstructure. The mechanism of the oxidation resistance of the coated graphite is also discussed. (c) 2006 Elsevier B.V. All rights reserved.