Understanding the complex mechanical behavior of stainless steel based composite coatings is important for engineering applications. The focus of this research was on gaining a fundamental understanding of the structure/property relationships that exist during structure formation of the coatings made by new low pressure cold spraying with propellant gas at the temperatures of 800-1000°C (warm spray). While composition is one of the key parameter in determining the final microstructure, the specific warm spray powder shock consolidation parameters (particle velocity and gas temperature) were found to have significant effects on the development of composite structure formation and mechanical properties. Microstructural examination and modeling results revealed that the strain localization mechanism differs from that of adiabatic shear band formation that results in large differences in the ensuing microstructure of the composite coating and its properties.

Surface preparation is very important for reliable adhesive bonding of cold sprayed coatings to the substrate. In this work, the grit blasting of low-carbon A516 steel substrates with Al 2 O 3 particles was studied and the roughness parameters Ra and Rt of the grit blasted surfaces were then measured. The influence of alumina grit size on the roughening of the A516 steel substrate, and the resulting effect on the roughness of the Cu coating – steel interface were studied. The results showed that variations of the grit blast size had significantly affected the resultant surface roughness of the substrate. The adhesive strength of the formed copper coatings on A516 steel substrates depends on the surface roughness and hardness of the base material. The adhesive strength about 110-200MPa was achieved. The specific features of the Cu coating-A516 steel interface topography were examined and discussed.

The main purpose of this study was to form cold sprayed copper coatings on A 516 low carbon steel, which is considered a prospective material for manufacturing used nuclear fuel containers. The 3 mm-thick Cu coatings were formed using the high pressure cold spray method with N 2 as the propellant gas. To increase the adhesion strength of the deposited coatings a copper sublayer was formed first, using He as the propellant gas. The deformation of copper particles during the deposition process was studied. The obtained SEM images of the Cu layer-A 516 low carbon steel substrate cross-sections demonstrated that the Cu sublayer had a dense microstructure, and local jet-metallic mixing areas. The Cu particles were deformed considerably more severely in the sub-layer than in the following layers. The steel substrate underwent severe deformation due to the impact of Cu particles. The mutual severe deformation of Cu particles and steel substrate resulted in a considerable increase of adhesion strength up to 120MPa. The structure of coatings and coating-substrate interface was studied by OIM, SEM and EDS.

The present study was carried out to evaluate the applicability of the Gas Dynamic Spraying (GDS) of different powder compositions for depositing wear-resistant composite coatings on iron and steel castings. This process, simply known as “cold spray,” utilizes the kinetic energy of particles sprayed at supersonic velocities to produce a bonding of the particles to the substrate. Ni and Cu based coatings containing W, Zn and TiC as reinforcement were made by the low pressure GDS technique and investigated. The coatings microstructures were studied by both optical and scanning electron microscopy. Phase composition, hardness and wear resistance of the GDS coatings were analyzed. The ball-on-disc sliding wear test was used for assessing the wear resistance characteristics of the coatings using a ceramic (Si 3 N 4 ) ball. W and TiC reinforced coatings showed the best wear performance. These were further evaluated in greater detail. In addition to the obtained test results, the application prospects for such GDS coatings were discussed.