Single-point scratch testing for understanding particle engagement in abrasion of multiphase materials

Abstract

The current research explores the influence of multi-asperity abrasive particles engagement on multiphase materials. WC-Co (WC-15.6% Co) and NbC-cermet (NbC-12% Ni–10% Mo2C) hard materials were tested using a scale down single point scratch tester. Multi-asperity scratch patterns were produced by implying multiple scratches on hardmetal surface by parallel and repeated sliding. Superimposition of interactions has been implemented to study the damage evaluation of close-up parallel scratches. The abrasive particle characteristics such as size and apex angle were replicated by the diamond indenter and their influence with different applied loads [1–20 N] and sliding speeds [0.2–5 mm/s] were studied. NbC-cermet and WC-Co show a decrease in friction coefficient by 20–46% and 11–30% respectively, while the indenter tip radius changes from 200 μm to 25 μm under the same operating conditions. The wear micro-mechanism mainly changes from plastic deformation to fracture when the load and tip radius is increased. An extensive comparative study shows NbC-cermet prematurely experiences fracture dominated failure than its reference WC-Co. Moreover, tip size defect from indenter curvature geometry greatly affects the mean apex angle.