Structure and Properties of the Hardmetal Coatings Cr3C2-25NiCr Formed by a Multi-chamber Detonation Sprayer

The hardmetal Cr3C2-25NiCr (180-220 μm thick) coatings have been produced on a steel substrate by a multi-chamber detonation sprayer (MCDS). The characteristic feature of MCDS is that the powder is accelerated by using combustion products that are formed in MCDS chambers and are converged before entering the nozzle, where they interact with the two-phase gas-powder cloud. The microstructures and properties of the hardmetal coatings were examined with the use of optical microscopy, scanning electron microscopy, X-ray phase analysis, and a Vickers hardness tester with a 300 g test load. Wear tests were carried out using a computer controlled pin-on-disc type tribometer. It was established that MCDS has provided the conditions for formation of a dense hardmetal Cr3C2-25NiCr (180-220 μm thick) coatings with a porosity of less than 0.02%, microhardness 540±210 HV0.3 and a specific wear rate of 9.08∙10-5 mm3(m∙N)-1.