Development of VC-Ni Eutectic Alloys for Wear Resistance

Abstract

Vanadium carbide is less dense, harder and tougher than tungsten carbide, and nickel is more corrosion resistant that cobalt. Replacing the binder with Ni should improve the corrosion resistance. Since there are eutectics with a wide range of compositions in the C-Ni-V system, this system has potential for wear resistant alloys with ~VC as the discrete hard phase and the nickel solid solution as the binder. The aim of this work was to ascertain if eutectic microstructures with vanadium carbides could be beneficial to wear resistance. Phase studies confirmed the wide range of the eutectic alloys, with VC + (Ni), VC + σ′, VC + (V) and graphite + (Ni) and different morphologies. Preliminary wear tests showed results comparable to WC-Co alloys.

Experimental Liquidus Surface Projection and Isothermal Section at 1000 °C of the V-Ni-C System

“…VC x at 1310°C between VC and Ni on pulverized arc-melted samples made from VC and Ni powders, using differential thermal analysis (DTA). The system had been reported by some of the current authors before, [17] , [58] - [60] but this paper provides the best values, because some of the previous values were not consistent, which led to incorrect interpretations. Thus, the most correct analyses and interpretations are given here.…”

“…Twenty-three alloy buttons of * 3 g were produced from V of 99.65% purity, and C and Ni of 99.99% purity by melting in a button arc-furnace under a pure argon atmosphere (* 99.99% purity), on a water-cooled copper hearth. [17] , [58] - [60] A titanium button was used as an oxygen and nitrogen getter and was melted prior to melting each sample. Each button was turned over and re-melted thrice to attempt homogeneity.…”

“…Also, information on the phase diagram work and structure property relations on V-Ni-C system is limited. [6,[14][15][16][17]…”

Preliminary study of spark plasma sintered VC-Ni alloys

“…Vanadium carbide (1.3-2.0 m) and nickel (2.2-2.7 m) powders of >99.5% purity were characterized using the scanning electron microscope (SEM) to determine their morphologies. Three alloys of compositions shown in Table 1 were selected, based on previous work [16,17]. Amounts of 25g of each powder composition were mixed by wet milling in a 250 ml zirconia oxide pot.…”

“…Some studies have been done on VC-Ni alloys [2,[14][15][16]. Apata et al [16] produced VC-Ni alloys by casting and V 49.1 C 28.8 Ni 22.1 (at. %) had 1052 HV 5 hardness and the best wear resistance.…”