Wetting and interfacial behavior of Sn-Ti alloys on zirconia

The isothermal wetting and spreading behaviors of Sn-Ti/ZrO2 systems were investigated by the sessile drop method, and the interfacial microstructures were characterized by XRD and TEM. The wettability improved significantly with the increase in Ti content or with the increase in temperature as a result of the interfacial phenomena. For example, for tests at 1000 degrees C, we found that: (1) X-Ti=0 to X-Ti=2.0%, the final contact angle decreased from 144 degrees to 42 degrees along with the increase in the coverage of ZrO2 by a Ti2O3 interfacial layer; (2) X-Ti=2.0% to X-Ti=4.0%, the contact angle decreased to 22 degrees because of the replacement of Ti2O3 by a more metallic layer; (3) X-Ti=4.0% to X-Ti=8.0%, no further decrease in the angle was observed as the interfacial layer remains Ti11.31Sn3O10. For X-Ti=4.0%, the temperature increase from 900 to 1000 degrees C led to a decrease in contact angle from 47 degrees to 22 degrees, respectively, due to the interfacial layer shifting from Ti2O3 to Ti11.31Sn3O10. For all the systems, the Ti enhanced the loss of oxygen from zirconia leading to the formation of black ZrO2-x. Spreading kinetics of Sn-Ti/ZrO2 systems was controlled by the reaction-limited dynamics. The diffusion of released oxygen changed the spreading rate in the rapid-spreading stage.