A Micromechanically Grounded Methodology for Evaluating the Abrasivity of Particles in Accelerated Tribological Tests

Abstract

This work proposes an improved methodology for evaluating the abrasivity of particles in accelerated tribological tests, extending a previously developed approach to materials testing under friction against loose abrasive. Instead of a single scalar sharpness measure, a micromechanically interpretable triplet of geometric descriptors {hmax, βmax, ρmin} is proposed–the protrusion height, the tangent rotation angle across the peak, and the minimum radius of curvature along the contour, computed from the analytical curvature of the elliptic Fourier reconstruction. This triplet is combined into a single dimensionless index κ* (effective cutting curvature index) that preserves the micromechanical interpretation of its components. On a sample of n = 200 silicon carbide 64C particles (50 particles at each of four test stages: 0, 250, 500, and 825 min in the steel 40/SiC 64C system), hmax is shown to be the dominant component of the triplet with respect to the test stage (Spearman ρ = −0.51, p < 10-13); the combined index κ* yields ρ = −0.46 (p < 10-10); the canonical SPLm parameter, implemented via elliptic Fourier reconstruction with N = 50 harmonics and piecewise-linear approximation of the peaks, yields ρ = −0.48 (p < 10-12) on the same sample. The advantage of the triplet and the combined κ* over SPLm lies in the transparent micromechanical interpretation of their components. A population balance model is constructed for the evolution of the log-normal moments of the shape parameters and coupled with the kinetics of wear intensity I(τ) as an a posteriori description of the two-scale structure of the kinetics. A direct fit of the kinetic data (33 intervals of 25 min duration) yielded a characteristic relaxation time τc = 24 min and, accordingly, an optimal duration of accelerated tests τ* = τc ln20 ≈ 72 min under the 5% criterion of |dI/dτ|0. The conclusions are directly substantiated for the investigated steel 40/SiC 64C system; verification on other counterbody materials and abrasives is the subject of further work. The obtained result increases the productivity of laboratory screening of materials and coatings and has direct value for production engineering systems.