The wetting of alumina ceramics was studied as a function of time and temperature by the sessile drop method using vacuum pressures of 10(-5) Pa. Contact angles as small as 38 degrees were obtained for the combination carbon coated alumina and an Al-2.5 at.% La alloy, in a time of 4500s and at a temperature of 1300 degrees C. On the other hand, for the single system alumina-aluminum the final contact angle was of 82 degrees after 7200 seconds at the same temperature. Considering the free formation energy of different oxides and carbides that can be formed between elements used in the present experiments are favorable thermodynamically and considering the observation of undercutting of the substrate and ridge formation at the leading edge of the liquid aluminum in all samples it can be concluded that wetting is enhanced thanks to different chemical reactions that occur at the ceramic-metal interface.

Keywords: wetting; carbon coated; alumina substrates; aluminum alloys