A Comparative Study on Tribocorrosion Wear Behavior of Boride and Vanadium Carbide Coatings Produced by TRD on AISI D2 Steel
Mehmet Veysel Çakır
Abstract
In this study, the surface of AISI D2 steel, which has the most common usage area among cold work tool steels, was coated with boride, vanadium carbide and boron-vanadium carbide layer by thermo-reactive deposition method. Characterization of obtained coatings was determined by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), two-dimensional (2D) surface roughness, microhardness, nanoindentation, and wear tests. Wear tests were carried out in an open-air and 3.5 wt % NaCl environment, taking into account the working conditions of AISI D2 steel, by using a ball-on-disc type tribometer with 10 N applying load and 250 m sliding distance. Characterization results revealed that, boride, carbide, and complex borocarbide coating layers were achieved. The thickness, hardness and elasticity of the obtained coating for boronizing, vanadinizing and borovanadinizing were respectively 124, 20, 98 µm thicknesses, 2176, 2250, 2338 HV hardness and 219, 169, 141 GPa elasticity modules. Depending on improving microhardness and elasticity modulus higher wear resistances were found in both open-air environments and 3.5 wt % NaCl environment than untreated AISI D2 steel. The wear environment is effective on the wear type. A lower friction coefficient and reduced wear rates occurred in 3.5 wt % NaCl environment compared to the open-air environment. In addition, while delamination and oxidative wear mechanisms were observed for coated samples in the open-air environment, delamination and pitting erosion mechanisms were observed in 3.5 wt % NaCl environment.