Structurization of Coatings in the Plasma Arc Spraying Process Using B4C + (Cr, Fe)7C3-Cored Wires

Abstract

The structure and phase composition acquired by coatings deposited in optimum mode by the plasma arc spraying process were examined. The spraying materials were wires with a steel sheath and nB4C + 100 – n(Cr, Fe)7C3 cores. The coatings have a ferrite matrix doped with Cr, B, and C and hardened with Fe3(B, C), Cr2B, FeCr, and boron carbide particles. When the (Cr, Fe)7C3 amount in the wire increases from 30 to 50 wt.%, the matrix phase (α-Fe-based solid solution) content decreases from 65.8 to 37.6 wt.% and the weight content of the hardening phases increases from 28.2 to 59.3%. These processes improve hardness of the coatings to 6.25 and 8.6 GPa, respectively. All coatings are characterized by a fine lamellar structure and high adhesion to the substrate. They exhibit high density and low porosity (<2.5%) and their hardness exceeds that of the wire steel sheath by 4.0 to 5.5 times. The plasma arc coatings can be used as wear-resistant materials for protection of chemical engineering equipment against abrasive wear, in the production of parts for pumps, compressors, and other machines, and for the recovery of worn parts.