1993 Volume 57 Issue 7 Pages 797-803
The effect of electroless copper plating 0.08 to 4.5 μm thick on the wettability of Al2O3 substrate and fiber preform by molten aluminum were investigated with the sessile drop method in a vacuum of 2×10−3 Pa at temperatures from 973 to 1173 K.
The contact angle of molten aluminum on Al2O3 substrate decreased from 113° to 92° as the temperature rose from 973 to 1173 K. The electroless copper plating on Al2O3 reduced the contact angle to less than 40° when the thickness of plating was larger than 0.3 μm at 973 K. The apparent contact angles between molten aluminum and 15 volume%Al2O3 fiber preform were about 140°∼145° at 973∼1073 K. Electroless copper plating reduced the angle, and molten aluminum was spontaneously infiltrated into preform when the thickness of plating was larger than 0.5 μm at 973 K, 1.4 μm at 1073 K. The thin copper plating could not improve the wettability, because copper deposits on Al2O3 coagulated due to the surface energy and the Al2O3 surface was partially exposed at high temperatures. The coagulation became more remarkable as temperature rose. By these phenomena, the molten Al drop, which once spread on the copper plated Al2O3 substrate, moved back towards the receding contact angle. The interaction between the coated copper and the molten aluminum was metallographically investigated.
