The effect of large oxygen additions on the wettability and work of adhesion of copper-oxygen alloys on polycrystalline alumina

The apparent contact angle, the solid-liquid interfacial energy, and the work of adhesion were determined for liquid copper and copper-oxygen alloys on polycrystalline alumina using a sessile drop technique. The oxygen contents were varied from 1 to 11 wt.% and the temperature was varied from 1135 to 1300°C. Most studies of this system have centered on considerably lower oxygen contents. In this study, three regions of wetting behavior were observed. These regions correlated with three liquid regions on the copper-oxygen binary phase diagram. For 0.001–3 wt.%, the contact angle decreased and the work of adhesion increased significantly as the oxygen content increased. Within the immiscible liquid composition range (3–7.5 wt.%), the contact angle and work of adhesion were approximately constant. At higher oxygen contents (8–10.5 wt.%), only slight changes in the contact angle and work of adhesion were observed. At 10.5 wt.%, the contact angle achieved a minimum of 12 ± 4° and the work of adhesion reached a maximum value of 1340 ± 60 mJ m−2.