Metal-Nanocarbon Composite Coatings Produced by Detonation Spraying with In Situ Carbon Generation

Metal matrix composites containing nanoscale carbon (nanotubes, graphene, etc.) are of great interest from the viewpoint of developing materials with improved mechanical properties. In the present work, detonation spraying experiments were conducted to produce composite coatings containing in situ generated nanoscale carbon. The coatings were prepared by detonation spraying with the use of fuel-rich acetylene-oxygen mixtures. When C2H2 + kO(2) mixtures with k < 1 detonate, together with gaseous detonation products, solid graphene-like carbon nanoparticles form in the detonation gun barrel. When spraying a powder, these particles enter the coating layer and affect its properties. The phase composition and mechanical properties of coatings obtained from Al, Cu, Ni and Ti powders in the mode of in situ carbon generation are reported. The microhardness of the carbon-containing composite coatings was higher than that of the pure metal coatings and bulk commercial metals. The cohesion of Al- and Cu-based coatings containing carbon and carbon-free coatings did not actually differ. However, the presence of carbon reduced the cohesion of the Ni-based coating by about 30% and, conversely, increased the cohesion of the Ti-based coating by 30%. This work opens a new avenue for research and applications in the area of coatings formed by detonation spraying.