It is well known that particle velocity before deposition is one of the most important parameters for fabrication of the high-quality cold sprayed coatings. In this work, 316L stainless steel powders were deposited on the substrate with the same material. The influence of particle size, morphology and processing parameters such as gas pressure (up to 4 MPa) and temperature (up to 1000°C), on particle velocity have been investigated using a DPV-2000 in-flight particle velocity monitoring system, followed by the measurement and analysis of deposition efficiency and coating mechanical properties including tensile strength and micro-hardness of the coatings. The results show that a higher particle velocity can be achieved by using particles with an angular morphology and a finer particle size. Higher particle velocities, resulting from higher working gas pressure and temperature, yield much denser coatings with higher deposition efficiency, micro-hardness and tensile strength.

CoNiCrAlY coatings are widely used as typical high-temperature materials to enhance the surface performances of nickel-based superalloy materials, which can be used as bond coats in thermal barrier coatings and abradable seal coatings. In this study, high-pressure cold spray technology was used to deposit CoNiCrAlY coatings on nickel-based superalloy substrates. The microstructure characteristics and oxidation behaviors of CoNiCrAlY coatings prepared by different gas types and cold spray parameters were systematically investigated. EBSD analysis showed that the deformation of the helium coating was more distinct, and the grain size of the coating fabricated by helium was smaller than that by nitrogen as seen from the grain morphology. The high-temperature oxidation results showed that the coating oxide film thickness varied parabolically with time for both coatings after 500 h isothermal oxidation at 800 °C, 900 °C, and 1000 °C, and the oxidation rate of the coating after heat treatment was lower than that of the as-sprayed coating. In addition, the shrinkage of the aluminum reservoir inside the coating, the element diffusion rate, and the amount and type of oxide generation on the surface all affected the oxidation process. Additionally, the helium coating had a lower oxidation growth rate and better oxidation resistance. Therefore, cold spray can be an alternative way to fabricate high-quality CoNiCrAlY coatings.

The aluminum-basalt fiber composite coating was prepared for the first time with basalt fiber as the spraying material by cold-spraying technology. Hybrid deposition behavior was studied by numerical simulation based on Fluent and ABAQUS. The microstructure of the composite coating was observed on the as-sprayed, cross-sectional, and fracture surfaces by SEM, focusing on the deposited morphology of the reinforcing phase basalt fibers in the coating, the distribution of basalt fibers, and the interaction between basalt fibers and metallic aluminum. The results show that there are four main morphologies of the basalt fiber-reinforced phase, i.e., transverse cracking, brittle fracture, deformation, and bending in the coating. At the same time, there are two modes of contact between aluminum and basalt fibers. Firstly, the thermally softened aluminum envelops the basalt fibers, forming a seamless connection. Secondly, the aluminum that has not undergone the softening effect creates a closed space, with the basalt fibers securely trapped within it. Moreover, the Rockwell hardness test and the friction-wear test were conducted on Al–basalt fiber composite coating, and the results showed that the composite coating has high wear resistance and high hardness.