激光与光电子学进展, 2019, 56 (24): 241403, 网络出版: 2019-11-26
激光功率对42CrMo熔覆Stellite-6涂层耐腐蚀性能的影响 下载: 846次
Effect of Laser Power on Corrosion Resistance of 42CrMo Cladding Stellite-6 Coating
激光技术 激光熔覆 Stellite-6涂层 电化学特性 腐蚀行为 抗腐蚀性 laser technique laser cladding Stellite-6 coating electrochemical properties corrosion behavior corrosion resistance
摘要
为提高42CrMo合金的耐腐蚀性能,采用激光熔覆工艺在不同的激光功率下于其表面制备Stellite-6涂层,然后采用浸泡实验、电化学方法研究Stellite-6涂层在3.5%NaCl溶液中的平均腐蚀速率与电化学特性,结合扫描电子显微镜对浸泡后试样的微观形貌进行分析。结果表明:不同激光功率下熔覆的Stellite-6涂层的平均腐蚀速率均远低于42CrMo基体材料的平均腐蚀速率,且涂层在NaCl溶液中的腐蚀行为以点蚀为主;激光功率对熔覆层质量有较大影响,当激光功率为2500 W时,开路电位为-0.15 V,自腐蚀电流为3.294×10 -3 A/cm 2,阻抗为6742.5 Ω·cm 2,此时熔池的形核率以及晶粒生长速率较大,晶粒细化,熔池区域的组织主要为细小的等轴晶,组织致密均匀,Stellite-6涂层的耐腐蚀性能最佳。腐蚀表面产生的Cr3C2钝化膜层使阳极活性受到抑制,钝化膜的保护作用明显,从而提高了涂层的耐腐蚀性能。
Abstract
To improve the corrosion resistance of the 42CrMo alloy, a Stellite-6 coating was prepared on the surface of the 42CrMo alloy by laser cladding. The average corrosion rate and electrochemical characteristics of the Stellite-6 coating in a 3.5% NaCl solution were studied through an immersion experiment and electrochemical workstation. After the immersion experiment, the samples were analyzed via scanning electron microscopy (SEM). The test results show that the average corrosion rate of the laser cladding Stellite-6 coating is considerably lower than that of the matrix. In addition, the corrosion behavior of the coating in a NaCl solution is mainly pitting corrosion. Laser power considerably affects the quality of the cladding layer. When the laser power is 2500 W, the open circuit potential is -0.15 V, self-corrosion current is 3.294×10 -3 A/cm 2, and impedance is 6742.5 Ω·cm 2. Furthermore, the nucleation and grain growth rates of the molten pool increase, the grain is refined, the microstructure of the molten pool primarily contains fine equiaxed crystals, and the structure is more dense and uniform. The Cr3C2 passivation film formed on the corrosion surface inhibits the anode activity. In addition, the passivation film is clearly protective, which improves the corrosion resistance of the coating.
崔宸, 武美萍, 程伟. 激光功率对42CrMo熔覆Stellite-6涂层耐腐蚀性能的影响[J]. 激光与光电子学进展, 2019, 56(24): 241403. Chen Cui, Meiping Wu, Wei Cheng. Effect of Laser Power on Corrosion Resistance of 42CrMo Cladding Stellite-6 Coating[J]. Laser & Optoelectronics Progress, 2019, 56(24): 241403.