Influence of carbon on the interfacial contact angle between alumina and liquid aluminum

Abstract

AbstractThe wetting of alumina by pure liquid aluminum was investigated over the temperature range 900–1300°C by the sessile drop method under a dynamic vacuum of 10−4–10−5 Pa. When the substrate is carbon coated, the terminal contact angle is reduced to 40° at 1300°C for times longer than 4500 s. In the absence of carbon, the final angle is 82° for the same conditions. Reactive wetting is suggested by the observation of undercutting of the substrate and ridge formation at the leading edge of the liquid aluminum in all carbon‐coated samples. Based on energy considerations, the following is among the thermodynamically favorable reactions: 4Al + 3C → Al4C3. Possible mechanisms for the observed carbon‐enhanced wettability in the system are discussed. Copyright © 2003 John Wiley & Sons, Ltd.