ELECTROSPARK DEPOSITION OF FeNiCrBSiC–MeB₂ COATINGS ON STEEL

Abstract

The effect of TiB₂ and CrB₂ additions to the commercial self-fluxing FeNiCrBSiC eutectic alloy on the electrospark deposition of coatings was examined. The mass transfer kinetics in the electrospark deposition of FTB20 (FeNiCrBSiC + 20% TiB₂) and FCB20 (FeNiCrBSiC + 20% СrВ₂) composite materials and commercial self-fluxing FeNiCrBSiC alloy coatings onto steel 45 using an Alier-52 unit was studied. It was determined that change in the energy parameters of electrospark deposition increased the mass transfer coefficient and the thickness and roughness of electrospark coatings. To reinforce the steel surfaces of machine parts operating under sliding friction conditions, application of the FTB20 and FCB20 coatings deposited using an Alier-52 unit (2 and 4 modes for 1–2 min/сm²) is recommended. The electrospark deposition of FTB20 and FCB20 electrodes leads to a heterophase structure on steel, consisting of the iron–nickel matrix and fine inclusions of chromium and/or titanium borides. The size of borides in the developed coatings is about 1 μm, which is one order of magnitude smaller than in the electrode materials (20 μm). In the deposition of the FCB20 electrode on steel, numerical cracks form in the modified layer and deteriorate the operational properties. The addition of TiB₂ and CrB₂ particles into the self-fluxing alloy increases the wear resistance of the electrospark coatings by four to five times as compared to the coating produced from the commercial self-fluxing FeNiCrBSiB alloy (PG-Zh14 grade).