Wettability of molten magnesium on carbon and AlN

Abstract

Good wettability between molten metals and solid ceramics is important to fabricate metal matrix composites via a casting route. In this work, the wettability of molten magnesium on carbon and AlN substrate was evaluated. To stabilize the shape of the magnesium drop, the chamber was filled with magnesium vapor prior to the wettability measurement. A good wettability was observed from the magnesium-carbon system. Initial contact angles of molten magnesium on the vitreous carbon and the porous graphite at 973 K were 80° and 74°, respectively. However, the molten magnesium did not show good wettability with AlN. The initial contact angle of molten magnesium on AlN was 119°. The effects of aluminum and zinc addition on the contact angle were also measured. The contact angle of molten Mg-Al alloy on AlN substrate were almost constant (119°) for aluminum additions in the range of 0 to 3 mass%, but mildly reduced to 115° when 10 mass% of aluminum was added. The contact angle of Mg-10 mass%Zn alloy on AlN substrate was 107°, which again was slightly lower than that of pure magnesium.