Wetting of Al/Sapphire (0001) System: Measurement Effect and Affecting Factors

Dynamic surface tension measurements of molten aluminum droplets on sapphire (0001) have been carried out at a PO(2) of 10(-15) Pa in a temperature range of 1073 to 1673 K. The aim is to demonstrate that the contact angles reported in the literature from 65 to 145 deg do not meet high-temperature adhesion requirements and often lead to incorrect measurements. This article demonstrates the use of modern techniques of analysis both in computation and image analysis, to revisit previous data that often show large variability. A sessile drop (SD) experiment and an image process through the solution and optimization of the Laplace equation of capillarity are addressed through MATLAB software. The approach delivers contact angles and surface tensions controlled with PO(2), temperature, and time. The details of the method and material properties affecting the system wettability by molten aluminum are also described.