Low pressure cold spraying (LPCS) is different from high pressure cold spraying because it is capable of onsite operation with compaction system and flexible spray gun. However, the deposition efficiency is much low for efficient onsite reparation, it is important to know more about the influence of spraying parameters on deposition efficiency of LPCS. To verify the relationship between the spray parameters (temperature, standoff distance, powder feeding rate, and transverse speed) and the deposition efficiency, a DYMET413 commercial LPCS system was used to prepare coating under different parameters. The deposition efficiency increases linearly as the gas temperature increases. The optimal alumina content in powders is about 30%, the optimal distance is 25 mm for the powder used in this study. The deposition efficiency of powder increases as the transverse speed of nozzle decreases. It is hard to predict the deposition efficiency by numerical methods since the deposition behavior in a composite powder system is influenced by a number of factors. The interaction between particles, the erosion effect of alumina and under critical velocity particles all can influence the deposition behavior.

Al B₄C composites structure manufactured by sintering method suffers from low strength and decomposition. To solve this problem, cold spray technology was used to manufacture Al B₄C composite coating on 5083 aluminium alloy. The results indicate that a high content (30 wt-%) B₄C reinforced Al coating can be deposited on aluminium substrate through cold spraying. The microstructure of the coating was characterized using scanning electron microscopy. It was found that the cold spray could deposit good quality aluminium coating with bonding strength ranging from 26.5 to 28.2 MPa. The average porosity for this coating in this case is about 1.5%, and the B₄C particles distribute uniformly in the coating. Electrochemical tests revealed that the cold sprayed Al + 30% B₄C coating has an inferior corrosion resistance to 5083 aluminium alloy in neutral 3.5 wt-% NaCl solution. Cold spray is a talented technology to manufacture Al B₄C Composites coating for neutron absorption application.

Zn-Ni-Al₂O₃ composite coatings with different Ni contents were fabricated by low-pressure cold spray (LPCS) technology. The effects of the Ni content on the microstructural and mechanical properties of the coatings were investigated. According to X-ray diffraction patterns, the composite coatings were primarily composed of metallic-phase Zn and Ni and ceramic-phase Al₂O₃. The energy-dispersive spectroscopy results show that the Al₂O₃ content of the composite coatings gradually decreased with increasing of Ni content. The cross-sectional morphology revealed thick, dense coatings with a wave-like stacking structure. The process of depositing Zn and Ni particles and Al₂O₃ particles by the LPCS method was examined, and the deposition mechanism was demonstrated to be mechanical interlocking. The bond strength, micro hardness and friction coefficient of the coatings did not obviously change when the Ni content varied. The presence of Al₂O₃ and Ni increased the wear resistance of the composite coatings, which was higher than that of pure Zn coatings, and the wear mechanism was abrasive and adhesive wear.

The purpose of this paper is to examine the influence of cold spraying parameters on the performance of Fe-based amorphous alloy (FAA) coating. A FeCoCrMoBCY amorphous alloy coating was prepared on a 40Cr substrate by cold-spraying with different gas pressures and temperatures. The results show that the spray temperature has no substantial effect on the amorphous content during deposition. The porosity of the FAA coatings decreases with the increase of the spray parameters. The hardness of the cold sprayed coatings decreases slightly as the spraying parameter decreases. Wear tests show that cold spraying FAA coating can provide excellent wear protection. The high porosity induced by the insufficient deformation of the hard FAA particles leads to an acceleration in corrosion for the substrate. Cold-spraying can be used to fabricate FAA coating with good wear resistance, but sealing is still necessary to guarantee the corrosion resistance since.

Cr doped MoS₂ films were deposited by magnetron sputtering. The tribological properties of Cr doped MoS₂ films under vacuum (VC) and air (AR) environments were investigated. The results show that Cr doped MoS₂ film with Cr target power of 0.2 A (0.2 A Cr:MoS₂ film) exhibits low friction coefficient and long wear life under both VC and AR environments. The chemical compositions of the films were analyzed by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). With the increases of Cr target power, the content of Cr increases. The cross-sectional FESEM morphologies show that the structure of the films changed from granular particles to column when the Cr target power increases from 0.2A to 0.4A. The wear mechanism has also been discussed based on the characteristics of worn surface. The 0.4 A Cr:MoS₂ film has the lowest wear volume among these films, which can be attributed to the compact microstructure. The bandgap of Cr doped MoS₂ films were measured by XPS and the tribological performance of the film is found to be best when there is a modest bandgap. It can be speculated that the tribological performance of Cr doped MoS₂ films are closely related to the width of bandgap.