Study on wetting mechanism of Sn3Sc alloy on silica and sapphire surfaces

Abstract

To further investigate the wetting mechanism of filler alloys containing active elements on oxide ceramics surfaces, we prepared a new filler alloy (Sn-3at.%Sc filler alloy) containing trace rare earth elements by vacuum melting furnace. Under high vacuum, its wetting behavior on silica and sapphire substrates was studied using a modified sessile drop method. The final contact angles of liquid Sn-3at.%Sc filler alloy on silica and sapphire surfaces are 6.0° and 9.8°, respectively, showing good wetting properties, and exhibiting similar wetting behavior at the same temperature. The same interfacial product Sc2O3 was detected at the interface of Sn-3at.%Sc/silica and Sn-3at.%Sc/sapphire systems. However, thermodynamic and spreading analysis suggests that Sc2O3 is precipitated in different ways at the interface of the two systems. The former is generated by an interfacial reaction, while the latter precipitates during the cooling process. The wettability of the Sn-3at.%Sc/silica system may depend on the interaction between the interface reaction products and residual scandium adsorption at the solid/liquid interface, while the wettability of Sn-3at.%Sc/sapphire system may depend on the adsorption of Sc-O clusters at the interface. These findings provide a theoretical basis and design ideas for further development of tin-based filler alloys and design of new type filler alloys.