Study of the 3C-SiC surface crystalline orientation effect on the wettability of molten aluminium droplets by molecular dynamics simulation

Aluminium silicon carbide (AlSiC) composites are silicon carbide (SiC) ceramic-reinforced aluminium matrix composites. When wide band-gap semiconductors, typically silicon carbide (SiC) and gallium nitride (GaN), work at high power density and high operating temperature, AlSiC is usually used as the thermal management material to dissipate a large amount of heat accumulated in the devices, thus reducing equipment failures caused by thermal runaway. Wetting is an important property to be considered because it can affect the heat transfer performance of AlSiC. The purpose of this work was to study the influence of 3 C-SiC crystalline orientation on the wetting behaviour of molten aluminum droplets through molecular dynamics simulation. The density distribution of Al droplets obtained on the (110) plane was stratified, while on the (111) plane, a relatively dense spindle region appeared. The physical quantities associated with the wettability of aluminium droplets on the (110) and (111) planes were also analysed. The contact angles on these two crystal planes obtained after fitting were 84.3 & DEG; and 95.3 & DEG;, respectively. The droplet exhibits a wetting state on the (110) plane while presenting characteristics between wetting and hydrophobicity on the (111) plane. The magnitude of the interface energy fluctuation of the (110) system was between - 17 kJ/mol and - 27 kJ/mol which was less than that of the (111) system. In the time step 2.85 x 105 fs before and after fitting, the average self-diffusion coefficients of aluminium droplets in the (111) system increased by 2.29 x 10-8 and 1.9 x 10- 7 m2/s compared with those in the (110) system. Although it was more difficult for molten aluminium to diffuse on the (110) plane, it took longer time for the (111) system to reach stability. This further showed that the role of the 3 C-SiC crystalline orientation on droplet wettability cannot be ignored. Therefore, understanding the influence of crystal orientation on the wetting characteristics of AlSiC during its preparation is helpful for improving its heat transfer performance, and to ensure the reliable operation of wide band-gap semiconductor devices.