Heteroepitaxial growth related to impact melting and mechanical interlocking in ceramic metallization using cold spraying

Abstract

Ceramic metallization by cold spraying is a burgeoning technology. However, the bonding mechanism of metallic particles and ceramic substrates is still in dispute. The copper particles and alumina substrates were employed to investigate the bonding mechanisms of ceramic metallization using cold spraying. The interfacial characteristics between the copper particles and alumina substrates were studied using a scanning electron microscope (SEM), transmission electron microscope (TEM), electron backscattered diffraction (EBSD), finite element simulation (FEA) and density functional theory (DFT). Throughout the investigation, impact melting and mechanical interlocking phenomena were observed in the bonding of the copper particles and alumina substrates. The heteroepitaxial growth was found at the interfaces with impact melting and mechanical interlocking. The difference is that the amorphous grains and nanocrystalline were found at the melting interfaces, but only the amorphous grains were observed at the interlocking interfaces. The impact melting of the copper particles hindered the bonding of the copper particles on the alumina substrates. The binding energy of the copper and alumina at the interlocking interfaces was higher than that at the melting interfaces. This investigation deepens the understanding of the bonding mechanisms of ceramic metallization using cold spraying.