Wettability of monocrystalline alumina by aluminium between its melting point and 1273 K
✍ Scribed by V. Laurent; D. Chatain; C. Chatillon; N. Eustathopoulos
- Publisher
- Elsevier Science
- Year
- 1988
- Weight
- 789 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0001-6160
No coin nor oath required. For personal study only.
✦ Synopsis
The wettability of A&O, single crystals by aluminium is investigated in the 933-1273 K temperature range by the sessile drop method under a low total pressure (4 x 10-JPa) and an oxygen partial pressure of about lo-" Pa. The variation of contact angle with temperature is shown to describe a linear decrease from 103 f 6" (933 K) to 86 & 6" (1273 K). The temperature coefficients of contact angle (dB/dT = -0.05 K-l) and work of adhesion (dW,/dT = 0.6 ml m-*K-l) are found to be similar to but somewhat higher than those obtained with non reactive metals (such as Cu and Au) on alumina. Results of several wetting tensiometer experiments performed with sapphire cylinders are in close agreement with the above-described wetting behaviour. It is shown that, with the experimental conditions described, the influence of the oxide layer surrounding the liquid metal on wettability can be eliminated from the melting point of Al. By evaluating the gaseous exchanges between the experimental chamber and the oxide layer, using the kinetic theory of gases for molecular flow, the process whereby aluminium is released from its surrounding oxide layer can be discussed. This process depends on the initial thickness of the oxide layer, the oxygen partial pressure and the temperature.