Study on adhesion mechanism of SiC_p/Al composites and electroless nickel coating

The morphology of the surface and the cross-section and the interface state of the coatings and aluminum matrix composite reinforced by silicon carbide particles (SiC_p/ Al) were investigated by SEM, EDAX and XPS techniques. Adhesion mechanism between Ni layer and substrate is analyzed. The results show that the coatings and the composites have excellent adhesion. The early Ni deposits tended to occur as microcrystalline layers on the SiC-Al interface due to growth extention according to Al crystal lattice. Then the adsorbed atoms diffused and integrated to matching growth with SiC lattice, which places a premium on the tension stress. This makes it clear that a bonding action has generated between matrix Ni and substrate particles and that Ni atom prefers to obtain electrons during the bonding process. The chemical bonding is formed the between coating and the substrate. The bond shows a mixed property of covalent bond and ionic bond.