Contact-Based Wear Modeling of Coated Deep Bores Manufactured by Electrochemical Rifling

This study presents an analytical–experimental investigation of the mechanical and tribological behaviour of two coating systems applied to deep, internally profiled cylindrical components manufactured via Electrochemical Rifling (ECR): a hard anodised aluminium oxide (AAO) coating on an aluminium alloy and a hard chromium coating on alloy steel. Experimental characterisation includes microhardness measurements, coefficient of friction determination, and controlled sliding wear tests. The chromium coating exhibits approximately 2.5 times higher microhardness and about 15% lower average coefficient of friction compared to the anodised aluminium layer, resulting in significantly improved wear resistance. Acceptable engineering agreement is observed between analytical predictions and experimental results. For chromium-coated steel, analytical predictions yield approximately 67,200–72,600 cycles, while the experimentally estimated value is about 36,200 cycles. For anodised aluminium, analytical predictions range from approximately 1688 to 2803 cycles, compared to an experimental value of about 2012 cycles. A conservative reliability-oriented criterion yields service lives of approximately 12,000 cycles for chromium coatings and 1000 cycles for anodised aluminium. Weibull-based analysis (R = 0.95) indicates service life ranges of approximately 9300–10,000 and 230–390 cycles, respectively.