Abstract
The effect of Ca addition on the wettability and the interaction of liquid Al on graphite, Al2O3, and SiO2 substrates has been investigated in the atmosphere of low pressure (0.27-0.67 kPa) H2 gas at temperatures over the range from 973 K to 1123 K by the sessile drop method.
Results obtained are as follows:
(1) The wetting angles between liquid Al and graphite, Al2O3 and SiO2 substrates show a tendency to decrease with 1-2%Ca addition and increasing temperature.
(2) The wetting angles of liquid Al and Al-Ca alloy on graphite substrates decreased with elapse of the wetting time at temperatures above 1123 K. This phenomenon is more remarkable at higher temperatures, and is considered to be due to the formation of Al carbide at the interface.
(3) The wettability of Al2O3 substrate by liquid Al-Ca alloy is almost unchanged by elapse of the wetting time and by the formation of Ca oxide at the interface.
(4) The wettability of SiO2 substrate by liquid Al has the time dependence, which is associated with the formation of significant amounts of interfacial compounds. On the other hand, by liquid Al-Ca alloy the wettability does not have the time dependence, and the formation of compounds is decreased with addition of Ca.
