New perspectives in hardmetal abrasion simulation

Abstract

The response of tungsten carbide hardmetals with differing binder chemistries and carbide grain sizes to a traversing diamond indenter under load has been investigated in two principal regimes; single pass traverses and a multi-pass regime intended to simulate two-body abrasion experienced when the hardmetal is worn by a hard, high crushing strength abradant. The two-body regime is intended to simulate in-field degradation modes witnessed when a non-compliant counterface is present. The multi-pass test is achieved by a desktop computer program which generates pre-set spatial distributions to define the lateral position of the individual abrasion events with the scratches generated accumulating as a model of an abrasion process. Surfaces (and pre-polished sub-surface sections) were analysed using SEM, optical relocation profilometry, x-ray energy dispersive analysis (EDS) and ion beam milling (FIB). By these means, physical and chemical changes could be analysed; namely surface and sub-surface grain micro-cracking, pluckout, debris generation and re-embedment, grain and binder plasticity and surface oxidation. A comparison is also made between the results of this evaluation and the microstructural mechanisms that occur in standardised macroscopic laboratory abrasion tests including ASTM G65 and ASTM B611.