Identification of Friction and Wear Regimes in Tribosystems Using Acoustic Emission: Dissipation Criterion, Metallographic Analysis, and Life Prediction Model

Abstract A methodology integrating acoustic emission (AE) power parameters, metallographic analysis, Fourier sub-block orientation analysis, and EDS mapping is developed for the identification of quasi-wearless friction regimes in tribosystems. A dimensionless dissipation coefficient ξ TC = µ*·W*/W L × 100% is introduced as a unified thermodynamic criterion separating Mode I (equilibrium self-organisation, ξ TC = 0.0836–0.0941%) from Mode II (non-equilibrium self-organisation, ξ TC = 6.86×10⁻⁴–6.94×10⁻⁴%). Three tribosystems are investigated over 36 controlled experiments: 12Kh2N4A steel disc–disc under boundary lubrication B3V (Б3В), VB23NTs bronze–30Kh3VA steel pair, and 30Kh3VA steel with PVD MoN–TiAlN coatings under ТС-1 lubricant. The life-prediction model's primary validated result is obtained for the PVD-coated Tribosystem C (R² = 0.992, mean error 3.4%, genuine blind hold-out verification on 17 independent experiments: 7 for calibration, 10 withheld); consistent Mode II regressions independently derived for Tribosystems A and B (R² = 0.992 for both, three experiments each, evaluated in-sample) corroborate the model across two further, structurally distinct material systems, though these smaller-sample fits should be regarded as preliminary. Metallographic evidence confirms rotational meso-deformation as the dominant Mode II mechanism in steel and selective thermo-diffusion in the bronze pair. The AE method sensitivity exceeds gravimetric measurement by two orders of magnitude, qualifying it as an ultra-low wear measurement technology.