WETTING BEHAVIOR IN THE AL-SI SIC SYSTEM - INTERFACE REACTIONS AND SOLUBILITY EFFECTS/

The sessile drop technique was used to study the wetting behaviour of Al-Si alloys on SiC sintered ceramic substrates under vacuum in the 70 0-1100 degrees C temperature interval. Al-Si alloys with Si concentrat ions up to 50% were tested. An expected non-wetting/wetting transition was observed at 900-1000 degrees C due to the presence of an alumina film surrounding the molten alloy. At higher temperatures wetting was observed and the Si concentration of the alloy has a marked effect on the measured contact angles, theta. At 1100 degrees C theta decreases from 55 degrees to 25 degrees when instead of pure Al an A112.3%Si or an A116.6%Si alloy is used. The suppression of the formation of a cont inuous Al4C3 layer at the interface and a process of dissolution and r econstruction of the SiC surface, due to the increased Si concentratio n of the Al-Si alloys, are the key factors to explain the observed beh aviour.