Structure and properties of copper–chromium composite coatings obtained by detonation spraying of powder mixtures of different particle sizes

Abstract

Composite coatings were obtained by detonation spraying of copper–chromium powder mixtures with varying particle sizes onto steel substrates. The mixtures used contained 50 wt. % chromium. The microstructure of the coatings was analyzed using light microscopy, scanning electron microscopy, and X-ray diffraction analysis. The microhardness and electrical resistivity of the resulting samples were measured. The phase composition of the coatings consisted of α‑Cu and β‑Cr. The chromium content in the coatings was reduced by 8–12 wt. % compared to the initial powder mixtures. The most uniform distribution of chromium particles in the copper matrix was observed when spraying mixtures consisting of 20–40 or 40–60 μm copper particles along with 20–40 μm chromium particles. The microhardness of these coatings is twice that of copper obtained by hot rolling. This is attributed to the influence of solid chromium particles, formation of a fine structure, and an increase in the density of defects in the crystal lattice of materials during detonation spraying. The electrical resistivity of the coatings is comparable to that of other materials with similar composition obtained by sintering and cladding methods.