The study employs X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and metallographic analysis to assess the phase composition and microstructural features of anodic and chrome coatings. In response to increasing demands for enhanced durability and corrosion resistance in defence applications, surface treatments have become an integral part of the barrel manufacturing process. Aluminium barrels were anodised, while steel barrels were hard chrome plated. The electrochemical rifling (ECR) process was conducted under optimised conditions: current ≈ 950 A, voltage ≈ 7 V, pressure ≈ 2.2 MPa and duration ≈ 176 s. Before coating deposition, the inner bore surface roughness was controlled at Ra = 0.8 µm, ensuring reliable adhesion of the subsequent layers. The XRD and EDS results confirmed near-stoichiometric compositions for both coating types. The anodised layers revealed aluminium and γ-Al2O3 phases, accompanied by minor intermetallic compounds, such as S (Al2CuMg), T (Al2Mg3Zn3) and η (MgZn2). Chrome-plated steel sample exhibited the presence of elemental chromium and goethite (β-FeOOH). These findings support the suitability of the ECR method as a foundation for high-performance coating systems in military applications.

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. The experimental characterisation includes microhardness measurements, coefficient of friction determination, and controlled sliding wear tests. The results indicate that the chromium coating exhibits approximately 3.2 times higher microhardness and a 16% lower average coefficient of friction compared to the anodised aluminium layer, leading to significantly improved wear resistance.A good agreement is observed between analytical predictions and experimental results. For the steel specimen, values of approximately 26,800 cycles (analytical) and 36,000 cycles (experimental) were obtained, while for the aluminium specimen the corresponding values are approximately 2,050 and 2,012 cycles.Considering the degradation mechanisms typical of hard chromium coatings, a conservative reliability-oriented criterion yields a functional service life of approximately 12,000 cycles for the chromium coating and around 1,000 cycles for the anodised aluminium coating. A Weibull-based reliability analysis (R = 0.95) indicates service lives of approximately 5,200 cycles and 433 cycles, respectively.

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.