メニスコグラフ法による溶融AlおよびAl-Si合金と黒鉛の濡れ性の測定

Abstract

Wetting of graphite by liquid aluminum and Al-Si alloys was studied at 1273 K in purified He-3 vol%H2 with the Meniscography.The wetting was divided into three characteristic stages with the change in adhesive tension (Fa): (1) Initial wetting with decreasing Fa due to dewetting of the specimen by the melt, (2) quasi-equilibrium in wetting with constant Fa, and (3) spreading of the melt at the surface of graphite with increasing Fa.The highest wetting speed was obtained with graphite/Al-20 mass%Si. SEM observations and X-ray data showed that Al4C3 was formed at the graphite/melt interface up to the addition of 10 mass%Si, and that SiC was formed by the Al-20 mass%Si melt during the holding. The phenomenon was caused by the energy change at the graphite/melt interface when the graphite reacted with the melt.The contact angle (θ) of graphite/aluminum calculated from the adhesive tension measured with the Meniscography became smaller than that with the sessile drop method at the third stage. The difference in θ was caused by the presence of an oxide film of the melt which inhibited the melt spreading. The oxide film formed over the meniscus was found to delay the stating time of spread by wetting in the Meniscographic examination.