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通过脉冲激光熔覆技术在低碳钢表面上制备高致密铁基非晶合金涂层,研究了不同脉冲频率对涂层组织与性能的影响。利用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度仪、电化学工作站等测试方法分别分析了涂层成形、组织特征、显微硬度与耐腐蚀性能。研究结果表明,涂层主要由非晶组成,随脉冲频率降低,涂层厚度减小,稀释率降低,非晶化程度升高;当脉冲频率为1.0 Hz时,涂层稀释率显著降低50%,且未析出明显结晶相。随脉冲频率降低,熔合区宽度减小,柱状晶沿外延生长趋势变小,涂层显微硬度表现为先增加后减小,耐腐蚀性能先明显增强后减弱,且在3.5%NaCl溶液中耐腐蚀性能明显优于316L不锈钢。当脉冲频率为1.0 Hz时,涂层结构致密,平均显微硬度最高,达HV 1315,约为基材的9倍,涂层自腐蚀电流密度及钝化电流密度最低,分别为1.81×10~(-8),7.10×10~(-7)A·cm~(-2),耐蚀性能表现最强。
The high density iron-based amorphous alloy coating was prepared on the surface of mild steel by pulse laser cladding and the effect of different pulse frequency on the microstructure and properties of the coating was studied. The forming, microstructure, microhardness and corrosion resistance of the coating were analyzed by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness tester and electrochemical workstation. . The results show that the coating is mainly composed of amorphous, with the pulse frequency decreases, the coating thickness decreases, the dilution rate decreases, the degree of amorphization increases; when the pulse frequency of 1.0 Hz, the coating dilution rate significantly reduced by 50% , And no obvious crystalline phase precipitated. With the decrease of pulse frequency, the width of fusion zone decreases and the epitaxial growth of columnar grains decreases. The microhardness of the coating increases firstly and then decreases, and the corrosion resistance firstly increases and then decreases. In 3.5% NaCl solution, Corrosion performance was significantly better than 316L stainless steel. When the pulse frequency is 1.0 Hz, the coating has a compact structure and the highest average microhardness reaches HV 1315, about 9 times that of the substrate. The self-corrosion current density and passivation current density of the coating are the lowest, which are 1.81 × 10 ~ (-8) and 7.10 × 10 ~ (-7) A · cm ~ (-2), respectively.