摘要
目的提高ER8高速车轮钢的耐磨和耐腐蚀性能,增强车轮使用寿命。方法在ER8车轮钢表面制备出Fe基合金粉末和Co基合金粉末2种涂层。借助SEM、XRD、纳米压痕仪等表征设备分析涂层的金相组织形貌、物相种类和纳米硬度。利用MFT-EC4000往复电化学摩擦磨损试验仪将试样置于酸雨溶液进行摩擦磨损试验及电化学腐蚀试验。结果涂层表面组织致密均匀,形成了良好的冶金结合,Fe基与Co基合金涂层分别呈现出“胞状”与“蜂窝状”,无明显孔洞、裂纹等缺陷。基体在低频(1 Hz)下发生轻微的磨粒磨损,中高频(2、4 Hz)下出现了严重的剥落、点蚀现象,其磨损机理主要为粘着磨损、氧化磨损和磨粒磨损,涂层磨损区域则无明显腐蚀与剥落现象。在高频下,Fe基涂层和Co基涂层的磨损率分别比基体减少46.10×10^(-5)mm^(3)/(N·m)和39.85×10^(-5)mm^(3)/(N·m)。同时,涂层的阻抗值显著提高,极化曲线测试结果显示,Fe基涂层、Co基涂层和基材的自腐蚀电位分别为–0.522、–0.381、–0.603 V,腐蚀密度分别为3.916、0.312、5.483μA/cm^(2)。结论修复后的车轮钢样品的耐磨损性能与耐腐蚀能力得到不同程度提高,相比之下,耐磨损方面Fe基合金涂层表现得更为优异;耐蚀性方面,Co基合金涂层略强于Fe基涂层。
Laser cladding is an advanced surface modification technology,which can improve the surface properties such as wear resistance,corrosion resistance,fatigue wear resistance,oxidation resistance of different powder materials without changing the substrates.The work aims to improve the wear and corrosion resistance of ER8 high-speed wheel steel to increase the service life of wheels.In order to compare the wear resistance and corrosion resistance of different powder coatings and substrates in acid rain solution,the laser cladding technology was used to improve the performance of ER8 high-speed wheel steel and improve the service life of wheels,so as to cope with the bad service environment of train wheels.The wear and corrosion resistance of Fe-based alloy coating and Co-based alloy coating in simulated acid rain solution were compared and analyzed.The wheel steel was cut into sample blocks of 30 mm×20 mm×5 mm,and the circular gap with width of 10 mm and maximum depth of 2 mm was removed in the middle part of the matrix material sample.The substrate was polished smooth and cleaned with sandpaper.Under the laser power of 1600 W,spot diameter of 4 mm,scanning rate of 7.5 mm/s and lap rate of 50%.Fe-based and Co-based alloy coatings were prepared by Laserline LDF6000-100 laser on the substrate surface.Then,the microstructure morphology,phase type and nano hardness of the coating were analyzed by SEM,XRD and nano indentation apparatus.With the help of MFT-EC4000 reciprocating electrochemical friction and wear tester,the samples were placed in acid rain solution for friction and wear test and electrochemical corrosion test.According to the results of uniform coating on the surface of compact structure,good metallurgical combination,Fe-based and Co-based alloy coating respectively presented"cellular"and"honeycomb".There was no obvious defects such as holes and cracks.The coating hardness is significantly higher than that of matrix hardness.The solid solution and carbide formation made Fe-based coating hardness more outstanding.The HV hardness was up to 714.4 on average.The substrate had light wear at low frequency(1 Hz)and,severe spalling,pitting corrosion at high frequency(2 Hz,4 Hz).The wear mechanisms were mainly adhesion wear,oxidative wear and abrasive wear.There was no obvious corrosion and peeling phenomenon in the coating wear area.At high frequency,the wear rate of Fe-based coating and Co-based coating decreased by 6.10×10^(-5)mm^(3)/(N·m)and 39.85×10^(-5)mm^(3)/(N·m),respectively.At the same time,the impedance value of the coating in acid rain solution was significantly increased,and the polarization curve test results showed that the self-corrosion potential of Fe-based coating,Co-based coating and substrate was–0.522 V,–0.381 V and–0.603 V,respectively.The corrosion densities were 3.916μA/cm^(2),0.312μA/cm^(2)and 5.483μA/cm^(2),respectively.The wear resistance and corrosion resistance of the repaired wheel steel samples are improved to varying degrees.In comparison,the wear resistance of the Fe-based alloy coating is more excellent.The corrosion resistance of Co-based alloy coating is slightly stronger than that of Fe base coating.
作者
杨文斌
夏金龙
肖乾
陈道云
刘新龙
YANG Wen-bin;XIA Jin-long;XIAO Qian;CHEN Dao-yun;LIU Xin-long(School of Mechatronics and Vehicle Engineering,East China Jiaotong University,Nanchang 330013,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第1期314-324,共11页
Surface Technology
基金
国家自然科学基金青年基金(51905172)
江西省自然科学基金(20202BABL214028)
江西省教育厅科学技术研究项目(GJJ180344)
江西省研究生创新专项资金项目(YC2021-S462)。
关键词
车轮钢
激光熔覆
合金粉末涂层
摩擦磨损
酸雨溶液
电化学腐蚀
wheel steel
laser cladding
alloy powder coating
friction and wear
acid rain solution
electrochemical corrosion
