Effect of spray angle on Ni particle deposition behaviour in cold spray

In this work, cold sprayed Ni particles depositing onto stainless steel (SS) and aluminium substrates was studied the deposition behaviour and bonding mechanism at different spray angles. Contrary to common investigation which is limited to the cross-section or surface, the fractured contact surface on deposited particle was obtained by detaching the as-sprayed particle from the substrate. The results show that the contact surface of Ni particle detached from Al substrate was smooth without signs of metallurgical bonding or interfacial remelting. Compared to the relatively hard SS substrate where dimple-like fractures were found, the substrate hardness is found to play an important role in the formation of metallurgical bonding. Additionally, finite element analysis results show that the relatively hard SS substrate leads to a higher maximum contact pressure, which can promote the formation of metallurgical bonding. It can be convinced that the high contact pressure area is the determining factor for metallurgical bonding.