ADHESION OF CERAMIC COATINGS SPRAYED ONTO GRAPHITE

In order to expand the fields of application and to improve the perfor mance of graphite (Cg), it is necessary to reduce its permeability tow ards oxygen and to limit its reactivity and especially its oxidation. It is therefore essential to protect it from the environment through t he use of ceramic coatings. Adhesion between ceramic coatings and grap hite is controlled by the mechanical stresses in the coatings and the thermodynamic work of adhesion. Different metal-graphite systems were examined and it was shown that the adhesion depended particularly on t he thermal expansion coefficient mismatch between the two materials an d on the stability of the metal carbide. Thus, the role of the additio n on the graphite surface of elements such as Cr, Mo, Al, Si, and O in the adhesion of metals or ceramics to graphite has been identified.