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The Al5056/SiC composite coatings were prepared by cold spraying. Experimental results show that the SiC content in the composite coating deposited with the SiC powder having an average size of 67 $\mu$m (Al5056/SiC-67) is similar to that deposited with the SiC powder having an average size of 27 $\mu$m (Al5056/SiC-27). The microhardness and cohesion strength of Al5056/SiC-67 coating are higher than those of the Al5056/SiC-27 coating. In addition, the Al5056/SiC-67 coating having a superior wear resistance because of the coarse SiC powder with a superior kinetic energy contributes to the deformation resistance of the matrix Al5056 particles.

The cold spraying process is analyzed by numerical modeling of the impact between a single spherical particle and a substrate; the effects of impact velocity and spray angle of a particle on the particle and substrate deformation behavior were investigated. It was found that much localized stress, localized strain, and localized heating are present near the particle/substrate interface. When impact velocity exceeds a critical velocity, a jet-type flow of material at the interface was formed. High particle/substrate contact pressures and better developed interfacial jets appear to be the major factors controlling the strength of interfacial bonding. As the particle impact velocity or spray angle increases, the length of interfacial jets increases and it may strengthen the bonding of the particle and the substrate.

An Al coating was sprayed on S355 steel using a cold spraying. The surface–interface morphologies, chemical compositions, and phases of the obtained Al coating were analyzed using a field emission scanning electronic microscope (FESEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively, and the chemical element distributions of Al coating surface and interface were also analyzed using a plane scan, and line scan, respectively. The salt spray corrosion (SSC) of cold sprayed Al coating was investigated using a neutral salt spray (NSS) test, the corrosion products on the Al coating were also analyzed using an EDS and XRD. The result shows that the cold sprayed Al coating is composed of Al phase, the Al particles are distorted when colliding with the substrate, the interface bonding mode is a mechanical bonding. The cold sprayed Al coating is covered with a stable corrosion products, which effectively prevents the coating from further SSC, showing an excellent corrosion resistance. The Al coating has appropriate cathodal protection potential, the corrosion rate of Al coating declines with the time in the electrochemical test.

Aluminum (Al) and its alloys are attractive for a variety of applications due to its advantages like light weight, ease of processing, and high thermal/electrical conductivities. However, it suffers short comings in terms of strength, wear resistance, and corrosion resistance. Thermal spray processes are widely used techniques for the surface property improvement like thermal, wear, and corrosion resistances of aluminum and other light metals. This paper summarizes the recent developments in thermal spraying and related technologies. Plasma spraying, flame spraying, and arc spraying are the chief thermal spraying techniques, whereas the HVOF and D-gun processes are the derivatives of flame spraying process. The cold spraying technique is an emerging coating technique where the particles are heated to a temperature lower than their melting point travel at high velocity and coat on impact with the target material by plastic deformation. Different parameters like heat source characteristics, coating material properties, substrate properties, and spray torch operating circumstances affect the coating microstructure and properties.

It is crucial to find a kind of method with environment protection, economics, high efficiency and feasibility to prepare the HA coating on the surface of the titanium and its alloy. In this study, a novel method, the high speed high pressure cold spraying was employed to prepare the HA coating on the surface of TC4 (a kind of titanium alloy). The cytotoxicity behaviors of coating and titanium alloy substrate were investigated. Hydroxyapatite-zirconia (HA-ZrO2) coating was deposited on TC4 titanium alloy substrate by cold spray (CS). According to the performances of the activity detection of the alkaline phosphatase (ALP) and the activities of aminopherase on the surface of the coating, the biology properties of coatings and substrate were investigated. The results show that the contents of neutyophil alkaline phosphatase on the surface of coating are much more than that on the surface of titanium alloy substrate. In addition, the absorption capacity data of albumin and fibronectin of the coating are much better obviously than that of the titanium substrate. The results indicate that the biology properties of the coating are much better than that of the substrate.