Theoretical and Experimental Study of Nickel-Based Self-Fluxing Materials

Nickel-based self-fluxing materials Ni-0.5C-15Cr-3.2Si-2B (PGSR-2) and Ni-1C-17Cr-4.1Si-3.6B (PGSR-4) are studied theoretically and experimentally. These materials are widely used to form wear-resistant coatings on various parts of machines and mechanisms, which are deposited by flame spraying, plasma spraying, and surfacing. To study the relation between the structures and properties and the main technological parameters is of interest to solve applied and theoretical problems. In addition, information on the structure of liquid alloys is necessary for designing and optimizing the deposition of gas-thermal coatings, since heat treatment of a melt can strongly affect the properties of solidified materials. One of the effective ways to solve this problem is the use of computer simulation methods. Thermodynamic simulation of the equilibrium compositions of the self-fluxing materials is carried out. When PGSR-2 and PGSR-4 are uniformly heated, Ni, Cr, C, Ni3B, Ni2B, NiB, Ni2Si, NiSi, CrB, and CrSi are shown to form in a condensed phase. In addition, when PGSR-4 is heated, Cr5B3, CrB2, and Cr(3)C(2)form in a condensed phase along with the above components. The microhardness and microstructure of the coatings deposited by plasma spraying are experimentally studied. The PGSR-2 coating is shown to be characterized by the presence of porosity across the thickness, and pores have an irregular shape and sizes from a few microns to 100 mu m, and the PGSR-4 powder coating is characterized by a high density, low porosity, and an even boundary with the substrate. The microhardness of PGSR-4 coating is significantly higher than that of PGSR-2, and the microhardness of both coatings is on average 3.0-4.0 times higher than that of the base.