关键词: P20钢, 双辉光离子渗氮, 物理气相沉积, 组织, 耐磨性, 耐蚀性

Abstract: CrN physical vapor deposition (PVD) was conducted respectively on the surface of P20 plastic mold steel without or after double glow plasma nitriding. The microstructure, element distribution, and phase composition of the nitrided, CrN deposited, and nitriding/CrN-deposition composite treated specimens were respectively analyzed using scanning electron microscope (SEM), electron probe microanalysis (EPMA), and X-ray diffractometer (XRD). The wear resistance was evaluated through wear scar morphology and 3D profilometry, while the corrosion resistance was tested via electrochemical experiments. The results indicate that a uniform and dense face-centered cubic (FCC) structured CrN coating is formed on the surface of the composite treated specimen, which mainly grows along the (111), (200), and (311) crystal planes. The surface hardness is significantly increased compared to the P20 steel substrate, reaching 1785 HV0.05. At the bottom of the coating, there is a compound layer composed of ε-Fe_(2,3)N and γ′-Fe₄N phases along with its diffusion layer, with an effective hardened layer depth of about 340 μm. Compared with the substrate and specimens subjected to single treatment, the nitriding/PVD-CrN composite treatment significantly improves the wear resistance of the P20 steel, as evidenced by obvious reductions in both the width and depth of wear scars. Moreover, the corrosion resistance is notably enhanced, with the self-corrosion current density decreasing from 7.71×10^-6 A/cm²(substrate) to 0.67×10^-6 A/cm².

Key words: P20 steel, double glow plasma nitriding, physical vapor deposition, microstructure, wear resistance, corrosion resistance