In the Cold Spray process, the sprayed particles are in solid state, and unlike thermal spray, the effect of the coating erosion by reflected particles can play a more significant role. This paper is an attempt of modeling the process of the Cold Spray coating formation taking into account the influence of the erosion process. The objective was to study the kinetics of the coating formation. Using an analytical approach, equations of the coating formation process are obtained. The approach is based on a comparison of the effect of particle adhesion to the coating combined with the effect of coating erosion. Adhesion and erosion are taken into account by introducing some probability values of these processes.

A model that takes into account the influence of surface activation by particles of the sprayed material on Cold Spray process is proposed in the present paper. With the help of this model, particle adhesion to the surface is numerically calculated. Some typical dependences of the coated area on the number of impacts for different particle velocities and temperatures are obtained. These dependences are in satisfactory agreement with the results of experiments.

This paper presents some results of modelling of the adhesive interaction of solid particles with the substrate at collision parameters characteristic for the Cold Spray process. A simple physical model based on comparison of adhesion energy and energy of elastic deformation generated under the particle impact is suggested. Empirical expressions for energies of adhesion and elastic deformation are obtained. It is shown that there is an optimal range of particle size and velocity providing high deposition efficiency for a given particle material. The results of the modeling are in good qualitative agreement with experimental data.

Cold Spray is a rapidly emerging technology with numerous applications that have not yet been realized. With the growth of this technology there will be a demand for laboratory systems to perform applications research and development as well as high volume production machines for specific industrial applications. The recent focus of Cold Spray equipment development has been to perfect nozzles and gun assemblies, gas heaters, gas flow, powder feed, and process control. This paper describes the automated equipment that is available in the market and presents some performance data. This equipment will serve as the prototype for the industrial equipment that will soon be designed and installed in industry for commercial production applications.

The rapid emergence of cold spray technology provides numerous applications that require spraying fine (<10 microns) powders, providing more uniform deposition, improved measurement of deposition efficiency and quick turn around time. The performance of high-pressure commercial powder feeders, currently available, lacks one or more of these desired performance characteristics. Further, researchers are interested in spraying many powders of different materials or particle size distributions where the powder feeder can be quickly and easily cleaned without replacing expensive consumables. The Ktech laboratory powder feeder has been designed to operate under a wide variety of carrier gas pressures (0 – 500 psig). This laboratory feeder delivers a continuous flow of powder, has a variable canister volume and is quick and easy to clean. This unique design facilitates short run research applications or higher volume extended run time dispensing. The feeder is designed to operate in either a locally or remotely through a PC based Ethernet connection. The laboratory powder feeder represents an excellent tool for high-pressure cold spray or low-pressure thermal spray processes requiring the delivery of fine powders.

A number of studies have been conducted over the past few years with the aim of modeling high-speed particle-substrate interactions during cold spraying. This paper summarizes the work conducted and some of the more important findings. Based on experimental measurements and dynamic deformation modeling, it is shown a radial jet of metal forms at the contact zone during cold spraying. The effect is similar to that observed in explosive welding and it leads to corona-shaped ejection of metal at the periphery of the contact zone. Paper includes a German-language abstract.

The interaction of the supersonic gas jets of rectangular section with a flat obstacle under conditions of the Cold Spray process was studied. Pressure distribution on the obstacle surface at various jet regimes is measured. Instability of the jet as well as compressed layer structure is observed with the aid of laser Schlieren visualization. Depending on jet pressure ratio, distance between nozzle exit and the obstacle various modes of the jet are registered including classical mode, the mode with peripheral maximum and circulate bands, the mode with oscillations of bow shock, and the mode with jet oscillations. It is shown that the distribution of pressure along the smaller size of the nozzle is self-similar in the classic regime of the impingement and does not depend on the angle of encounting at φ= 50 - 90°. The critical parameters of the gas, when it accelerates along the surface, are reached near the boundary of the falling jet. The distributions of the stagnation temperature and heat transfer coefficient in the near-wall jet at various stand-off distances are experimentally obtained. It is shown that the experimental data on the heat transfer coefficient are higher than the calculated ones, and this difference can be explained by velocity fluctuations in the vicinity of the stagnation point and in the near wall jet.

This paper considers the problem of spraying the electrically conductive coatings on electrotechnical units for different purposes with the method of cold gas-dynamic spraying. It presents a general scheme of the spraying system, the characteristics of the spraying process and the main results of the property tests of electrotechnical units with coatings. The contact connections of copper bars provided with aluminum caps with protective coatings of copper, zinc, and nickel are tested. The paper demonstrates the conformity of the electrotechnical units injected using the CGS method with the requirements of the state standard. It was observed that while spraying the thin copper layer on aluminum caps by the CGS method the copper expenditurer 50 times decreases. The technical characteristics, with this, are close to the copper caps, and the cost is close to the aluminum caps. Paper includes a German-language abstract.

The Cold Gas-Dynamic Spray Method (CGSM) is a means of producing coatings or free-standing structures from powder feedstocks, on metallic, polymeric or ceramic substrates, through the use of high particle velocities obtained by the control of gas dynamics in converging-diverging nozzles. The method expands the existing temperature-velocity domain of thermal-spray technology by permitting formation of coatings at relatively low temperatures with spray patterns governed largely by the gas dynamics of the nozzle. The coatings are formed by the energetic impact of the feedstock particles, whereby inter-particle bonding appears to be governed by the deformation of the particles accompanied by creation of copious amounts of fresh surface area available for interparticle bonding. Because of the novelty of the process, very little basic information exists regarding the mechanical properties and microstructure of the coatings. This work reports the outcome of investigations aimed at more clearly understanding the mechanical properties and microstructural characteristics of prototypical CGSM coatings formed from commercial copper and steel powders. Techniques include optical, scanning and transmission electron microscopies, microhardness and residual stress measurements. Early results suggest the materials to have significantly different properties than coatings made by more traditional thermal spray or cladding processes.