Effect of Target Magnetic Field Intensity on the Microstructure and Properties of Arc Ion Plated Cr Coatings
Arc ion plating of chromium coatings on 40CrNi alloy steel was systematically investigated as a function of target surface magnetic field intensity (3, 6, 9, and 12 Gs). Scanning electron microscopy, X-ray diffraction, microhardness testing, tribological analysis, scratch adhesion testing, and electrochemical polarization were employed to correlate arc spot dynamics with coating microstructure, mechanical properties, and corrosion resistance. Increasing the magnetic field from 3 to 12 Gs initially reduced and then increased surface roughness and macroparticle density, while deposition rate peaked and grain size reached a minimum at intermediate field strengths. The optimal field intensity of 9 Gs produced a maximum hardness of 470.84 HV0.05, a minimum friction coefficient of 0.42, a minimum wear volume of 1.06×10−7 mm3/(N·m), a maximum adhesion strength of 40.3 N, a corrosion potential of 76.1 mV, and a corrosion current density of 7.57×10−10 A/cm2. At 3 and 12 Gs, fatigue wear dominated; at 6 and 9 Gs, abrasive wear prevailed. These results demonstrate that target magnetic field intensity is a decisive process parameter for tailoring arc spot motion, refining grain structure, suppressing macroparticle emission, and enhancing the combined mechanical and corrosion performance of arc ion plated Cr coatings.