Cold gas dynamic spraying of aluminum: The role of substrate characteristics in deposit formation

摘要: Aluminum powder of 99.7 wt.% purity and in the nominal particle size range −75+15 µm has been sprayed onto a substrates by cold gas dynamic spraying (cold spraying) with helium, at room temperature, as accelerating gas. The examined include metals hardness, polymers, ceramics. substrate surfaces had low roughness (R < 0.1 µm) before deposition aluminum an attempt to separate effects mechanical bonding from other forms bonding, such chemical or metallurgical bonding. cross-sectional area single track was taken measure ease initiation deposition, assuming that once coating begun deposit substrate, its growth would occur constant rate regardless type. It shown depends critically upon For where not easy, small particles were deposited preferentially large ones (due their higher impact velocities); these may have acted interlayer promote further building coating. A number phenomena observed following various substrates, melting, deformation, evidence for formation metal-jet (akin seen explosive welding). Such related processes occurring during on substrate. Generally, poor nonmetallic materials (where no metallic between possible) very soft (in case tin, melting observed). Metallic harder than generally promoted although alloy difficult due presence tenacious oxide layer. Initiation be rapid hard even when deformation visible.