Abstract
Laser cladding allows obtaining hardening and restorative coatings and is widely used in various branches of engineering. Self-fluxing Ni-Cr-B-Si alloys proved to be wear-resistant alloys for deposition. The relatively low melting point of NiCrBSi powders allows adding hard particles in the matrix material and, thereby, creating composite coatings with particles not dissolved during the deposition. WC/W2C, Cr3C2, SiC, TaC, NiC, VC, and TiC additives are used as reinforcing carbide particles when creating composite coatings based on NiCrBSi. The study of wear patterns of the NiCrBSi-Cr3C2 composite coating characterized by the increased resistance to corrosion and oxidation at high temperatures is of particular scientific and practical interest. When studying, the authors added 15 wt. % of Cr3C2 powder with the particle size of 50-150 μm to PG-SR2 powder (chemical composition, wt. %: 0.48 % C; 14.8 % Cr; 2.6 % Fe; 2.9 % Si; 2.1 % B; the rest is Ni) with the particle size of 40-160 µm during gas powder laser cladding. Using scanning electron microscopy, the authors identified that such addition of chromium carbide to NiCrBSi powder caused the formation of a composite coating during laser cladding since the structure contains the initial nondissolved Cr3C2 chromium carbides. NiCrBSi - Cr3C2 coating has improved microhardness. The authors carried out abrasion tests for fixed abrasive material - corundum, determined abrasive wear intensity, friction coefficient, and specific work of abrasive wear, and studied the wear surfaces of NiCrBSi and NiCrBSi-Cr3C2 coatings. The study identified a significant increase in abrasive wear resistance of the composite coating in response to the change of the main wear mechanism (from micro-cutting for NiCrBSi coating to scratching for NiCrBSi-Cr3C2 coating).
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