Wettability and spreading kinetics of molten aluminum on copper-coated ceramics

The purpose of this study was to investigate the influence of Cu-coating on the spreading kinetics and equilibrium contact angles of aluminum on ceramics using a sessile drop technique. Al2O3 and SiC plates were coated by electroless plating. The copper film overcomes the low wetting of the uncoated samples by dissolution in the drop at 800 degrees C in argon, showing an intrinsically favorable effect on the adhesion energy. Just after 2 min, the contact angle decreased to 12.6 degrees and 26 degrees for Al/Cu-Al2O3 and Al/Cu-SiC, respectively. However, a de-wetting behavior was observed, reaching equilibrium contact angles of 58.3 degrees and 45.5 degrees for the couples. The dissolution reaction rate at the triple junction was so high that the spreading process was controlled by local diffusion rather than chemical reaction kinetics.