Microstructure, Mechanical Properties and Wear Behaviors of Ultrafine-Grain WC-Based Cermets with Different Binder Phases Fabricated by Spark Plasma Sintering

Abstract

In this work, to explore potential substitutions for the Co binder phase, ultrafine-grain WC-based cermets with various binder phases of Co, Ni and AlCoCrNiFeCu HEA were prepared using the SPS method. Based on SPS, WC-based cermets were fabricated at higher speed, showing fine carbide particles less than 410 μm. The microstructure, mechanical properties and wear properties were systematically evaluated. By comparison, the grain size of WC was the lowest for WC-10Co, while WC-10 HEA cermet held the coarsest WC particles. The hardness and fracture toughness of WC-10 HEA were the best among all three samples, with values of 93.2 HRA and 11.3 MP·m1/2. However, the bending strength of WC-10HEA was about 56.1% lower than that of WC-10Co, with a value of 1349.6 MPa. The reduction in bending strength is attributed to the lower density, formation of a newly Cr-Al rich phase and coarser WC grains. In dry sliding wear conditions, WC-10 HEA showed the lowest wear rate (0.98 × 10−6 mm3/(N·m)) and coefficient of friction (0.19), indicating the best wear resistance performance. This reveals that WC-based cermet with a HEA binder phase has superior wear performance due to the higher hardness and good self-lubricating effect of the wear products.

Effect of Si3N4 Additive on Microstructure and Mechanical Properties of Ti(C,N)-Based Cermet Cutting Tools

“…The grain size of Ti(C,N)-based cermets has a major impact on their mechanical properties and overall performance, particularly Vickers hardness and fracture toughness. The specimens with smaller particles possess lower fracture toughness and a higher hardness, whereas coarse grains have a higher fracture toughness and a lower hardness [ 42 ]. Reduced distances between grain boundaries and the heightened effects of strengthening grain boundaries are two ways that smaller grain sizes in Ti(C,N) particles can lead to greater hardness.…”

“…The formation and creation of the core/rim structure have a brilliant influence on the cracking path impedance during the indentation. The fracture toughness can be identified by the created crack path, which includes crack bridge, crack deflection, grain pull-out, crack branching, intergranular, and transgranular, by energy consumption [ 42 ]. With a change in the Si 3 N 4 content, there is a relatively noticeable effect on the formed crack path.…”