纯镁表面等离子体电解渗硼改性层的制备及性能EI北大核心CSCD

在硼砂体系电解液中对纯镁进行等离子体电解渗硼(PEB),以提高其硬度、耐磨性和耐蚀性。用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分别对PEB表面改性层的微观结构、元素分布和物相组成进行研究,并用显微硬度计与摩擦磨损试验机对PEB表面改性层的硬度和耐磨性进行表征,同时用动电位极化曲线及电化学阻抗谱(EIS)来评估PEB表面改性层的耐蚀性。另外,还分析PEB表面改性层的生成机理,并建立物理模型。结果表明,PEB表面改性层由氧化层和扩散层组成,且在PEB表面改性层中检测到MgB_(2)新物相。PEB表面改性层的最大硬度约为480HV,是基体硬度的近16倍;摩擦因数仅为0.11,比基体减小了70.27%,磨损率为1.62×10^(-9)m^(3)/(N·m),比基体减小1个数量级;腐蚀电流密度比基体减小1个数量级,容抗弧半径和阻抗模值均比基体大,即纯镁经等离子体电解渗硼处理后,硬度、耐磨性和耐蚀性均得到提高。

Fabrication and Performances of Surface Modified Layers Obtained by Plasma Electrolytic Boronizing on Pure Magnesium

Pure magnesium is treated by plasma electrolytic boronizing (PEB) in borax aqueous solution to prepare a novel surface modified layer to improve its micro-hardness, wear resistance and corrosion resistance. The microstructure, element distribution and phase composition of the PEB surface modified layer are investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. Vickers micro-hardness tester, friction and wear tester are employed to characterize the micro-hardness, wear resistance of the PEB surface modified layer, respectively. Meanwhile, the corrosion resistance of the PEB surface modified layer is evaluated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). In addition, the mechanism of formation of PEB surface modified layer is also analyzed, and the corresponding physical model is built. The results indicate that the obtained PEB surface modified layer consists of the oxide layer and the diffusion layer. A new phase MgB₂ is detected in the PEB surface modified layer. The maximum micro-hardness of the PEB surface modified layer is about 480 HV, which is almost 16 times than that of the substrate. The friction factor of the PEB surface modified layer is merely 0.11, which decreases by 70.27% in comparison with the substrate. The wear rate of the PEB surface modified layer is about 1.62×10^?9 m³ / (N·m), which is one order of magnitude lower than that of the substrate. Compared with the substrate, the corrosion current density of the PEB surface modified layer decreases by one order of magnitude, meanwhile both the capacitive loop radius and the impedance modulus increase. Namely, the micro-hardness, wear resistance and corrosion resistance of pure magnesium can be all improved by PEB treatment.