Cermets are composite materials consisting of a ceramic reinforcement and a metal matrix. Conventional tungsten carbide cermet parts containing a cobalt matrix phase are mainly produced by powder sintering. Laser Powder Bed Fusion (L-PBF) is an additive manufacturing technology widely applied for direct fabrication of metal functional parts with complex geometry. The present paper deals with the feasibility study of additive manufacturing of cermet parts by L-PBF using WC-17Co powder. The results showed that parametric optimisation of the L-PBF process allowed the production of solid WC-17Co part. Structural analysis revealed the presence of significant porosity (1.41%) and small-scale cracks in the as-built samples. Post-processing, such as HIP (Hot Isostatic Pressure) significantly improved the structure of manufactured parts. The porosity after HIP was very low (0.01%) and phase analysis revealed that the samples after HIP did not contain the fragile W 2 C phase. Abrasive wear tests showed that the wear resistance performance of additively manufactured parts was comparable to a reference produced by powder sintering. High values of hardness (around 1100 HV 30 ) were observed for the as-built and HIP samples. The study successfully demonstrated the possibility of manufacturing wear-resistant cermet parts by L-PBF.

Cold and detonation spraying methods are based on the interaction of high-velocity particles with substrate. High quality coatings from various powder materials can be deposited. In both processes, the substrate experiences insignificant thermal effect. Thermally sensitive powder can be sprayed with no oxidation and decomposition. The initial powder microstructure and even nanostructure can be preserved under properly selected spraying conditions. This study is based on a comparative analysis of the mechanical, electrical, and heat transfer properties of a series of coatings deposited by cold and detonation spraying technologies. The coatings are produced from copper and aluminum powders using a commercial Cold Spray equipment CGT-4000 and an original computer-controlled detonation spraying (CCDS) installation developed by the authors. The coating microhardness, density, electrical and heat conductivity, adhesion, cohesion, etc. are measured and compared. Particular advantages and drawbacks of both spraying methods are discussed.

Spraying metal-ceramic coatings is a complicated task because, in addition to the spray parameters of the metal particles, it is necessary to take into account those of ceramics. This paper presents some results concerning the effect of the nature, particle size, and velocity of ceramics on the metal-ceramic coating properties. Copper and aluminium powders are used as metal components. Two fractions (fine and coarse) of aluminium oxide and silicon carbide are sprayed in the tests. Ceramic particle velocity is varied by the particle injection into different zones of the gas flow: in the subsonic (pre-chamber) and supersonic parts of the nozzle, and in the free jet after the nozzle exit. Simulation results and measurements of the particle velocity by the track method are compared. Influence of the ceramic particle parameters on the coating formation process and its properties is discussed.

Particle-at-impact parameters in Cold Spray are governed mostly by gas flow parameters. However, the location of the powder injection can be used as independent factor to modify particle-in-flight parameters. Calculations and experiments confirm strong influence of the location of the powder injection on dynamics of particle acceleration and heating. Application of this effect for cold spraying of multicomponent coatings is a new and promising approach. The general scheme of spraying of two-component mixture composed of hard-sprayable and easy-sprayable components proposed as follows: The hard-sprayable component is injected into the subsonic part of the nozzle at a gas stagnation temperature favorable for this material to start the coating formation alone. The zone of injection of the easy-sprayable component is determined in such a way that the particles of this material have, at the nozzle outlet, values of temperature and velocity sufficient for the coating formation at the selected gas stagnation temperature. New design of spraying nozzle for the above purposes is proposed and discussed.

This paper presents some results of investigation of the cold spraying various composites including metal-ceramics, metal-metal with a new nozzle design. The objective of this study was to develop a nozzle with an ejector that allows the injection of powder components in different points of the gas flow that can provide optimal spray parameters for each component. For this purpose the installation was equipped with three feeders and three powder feed ports. The first one was located in a pre-chamber (high pressure powder feeder) and two others were located in the ejector in supersonic part of the nozzle. Varying the powder injection location of any component allowed us to change the spray parameters of the mixture. Some preliminary spray results of different powder mixtures are presented to illustrate possibilities of such approach. It is shown that an addition of ceramic or metal powder to the sprayed metal can significantly change the spray process and coating characteristics