Self-Sharpening of Tools with Unilateral Braze Coating Fabricated Using WC- and Ni-Based Alloys

Key Words:SURFACE MODIFICATION; MICROSTRUCTURE; PERFORMANCE; BEHAVIOR

Abstract:Tools such as agricultural grass cutters, stubble blades, machetes, and grain crushing knives can become passivated gradually during use without self-sharpening. To resolve this problem, a composite coating of a Ni-based alloy and tungsten carbide (WC) was brazed onto the unilateral surface of 45 steel tools. To ensure that the unilateral coating tool can self-sharpen, different heat treatments were tested that can change the microstructure of the substrate. This makes it possible to regulate the wear resistance on both sides of the tool. Previous research shows that multiple phases can coexist at the interface between WC and Ni-based brazing alloys. These can decrease the initial melting temperature and the finishing melting temperature of the coating by 30.7 degrees C and 49 degrees C, respectively. A quantitative wear test of the tool indicates that the material-removal rate of the coating and the substrate is inversely proportional to its hardness. As a result, the optimal coating thickness can be estimated using the material-removal rate, i.e., the wear. A plowing simulation in gravel shows that after long-time usage (for example, 100 h), the tool, which was treated with quenching/tempering, is very good at self-sharpening. Moreover, the shortening in the direction of the symmetry line of the tool is small. The aim of the study is to improve both self-sharpening and service life of the tools.

Volume:48

Issue:5

Translation or Not:no