引用本文:聂开勋,杨秀杰,费佳玟,唐正强,吴兵.盐浴氮化对电工纯铁腐蚀磨损性能的影响[J].中国表面工程,2023,36(5):234~247
NIE Kaixun,YANG Xiujie,FEI Jiawen,TANG Zhengqiang,WU Bing.Effect of Salt-bath Nitriding on Corrosive Wear Performance of Pure Iron[J].China Surface Engineering,2023,36(5):234~247
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盐浴氮化对电工纯铁腐蚀磨损性能的影响
聂开勋, 杨秀杰, 费佳玟, 唐正强, 吴兵
贵州大学机械工程学院 贵阳 550025
摘要:
盐浴渗氮作为一种有效提高金属材料性能的化学热处理技术而被广泛研究,但目前鲜有在电工纯铁上的应用报道,且缺乏在不同环境下的磨损性能研究。采用盐浴氮化对电工纯铁进行处理,采用 SEM、显微硬度计、XRD、XPS、盐雾测试箱、 电化学工作站、摩擦磨损试验机等测试手段对渗氮层的微观组织、硬度、腐蚀行为及不同环境下的磨损行为进行测试分析。 结果表明,经过渗氮处理后在试样表面形成主要为 ε-Fe3N、γ′-Fe4N 相的渗层,矫顽力和表面硬度随氮化温度和时间的增加逐渐升高,截面硬度呈梯度分布。其中 580 ℃×4.5 h 工艺试样具有最优的耐腐蚀性能,自腐蚀电位较纯铁正移,自腐蚀电流密度低于纯铁,电荷转移电阻提升了 7.7 倍。空气环境下,氮化试样的摩擦因数比纯铁低,氮化试样磨损率只约为纯铁的 1 / 2; 去离子水与 3.5 wt.% NaCl 溶液环境皆有利于降低摩擦因数,但增加了磨损率,3.5 wt.% NaCl 溶液环境对材料的加速磨损效果比去离子水更明显。系统研究了盐浴渗氮对电工纯铁腐蚀磨损性能的影响,可为提升海工装备电气开关元器件的服役寿命提供一定理论指导与技术支持。
关键词:  电工纯铁  盐浴氮化  腐蚀  耐磨性  磨损机制
DOI:10.11933/j.issn.1007-9289.20221222002
分类号:TG174
基金项目:贵州省科技计划(黔科合基础[2020]1Y415);贵州省科技支撑计划(黔科合支撑[2021]一般 363);贵州大学培育([2019]24 号)资助项目
Effect of Salt-bath Nitriding on Corrosive Wear Performance of Pure Iron
NIE Kaixun, YANG Xiujie, FEI Jiawen, TANG Zhengqiang, WU Bing
School of Mechanical Engineering, Guizhou University, Guiyang 550025 , China
Abstract:
As a soft magnetic material, pure iron has excellent magnetic properties such as low coercivity and high permeability. Consequently, it has been widely used in circuit breakers, electromagnetic relays, and other electronic components, such as iron cores, and armatures. However, the application of pure iron in extreme environments has been limited, owing to its poor corrosion and wear performance. Salt-bath nitriding is widely studied as a chemical heat treatment technology that can effectively improve the properties of metal materials. However, there are few reports on applying this treatment to pure iron, and there is a lack of research on the wear properties of pure iron in different environments. In order to improve the hardness, wear resistance, and corrosion resistance of pure iron, and enhance the service life of electrical switch components of marine equipment, pure iron samples underwent a salt-bath nitriding treatment. Scanning electron microscopy was used to determine the micromorphology of the surface and the nitrided layer section, and determine the wear mark morphology. The wear products were analyzed by energy-dispersive X-ray spectroscopy. X-ray diffraction analysis was used to conduct phase analysis of the surface of the nitrided layer, while X-ray photoelectron spectroscopy was used to conduct specific phase composition analysis before and after the removal of the loose layer on the surface of the nitrided layer. The surface and section hardness distribution was tested with a microhardness tester, and the corrosion resistance was tested and analyzed with a neutral salt spray test box and electrochemical workstation. The wear performance of the samples before and after nitriding was tested on the ball-disk friction and wear tester, and the test environment was an air, deionized water, and 3.5 wt.% NaCl solution environment. The results showed that the maximum coercivity and surface hardness values were 31.5 A / m and 508.8 HV0.2, respectively, with the values increasing with an increase in nitriding temperature and time. The 580 ℃×4.5 h process sample had the best resistance to neutral salt spray corrosion, and the thickness of the sample after this process was about 200 μm. The sample had ε-Fe3N and γ′-Fe4N phases, with the formation of hard ε-Fe3N and γ′-Fe4N phases being the main reason for the increase of surface hardness. The hardness of the cross section of the sample increases slightly at first and then decreases gradually from the nitrided layer to the matrix. The maximum hardness value was 528.1 HV0.2. The self-corrosion potential of the 580 ℃×4.5 h process sample shifted 0.37 V forward, the self-corrosion current density was significantly reduced, and the charge transfer resistance increased by 7.7 times relative to the respective pure iron values. The improvement in the corrosion performance can be attributed to the improved compactness and chemical stability of the nitrided layer. In an air environment, the friction coefficient of the nitriding sample is lower than that of pure iron, and the wear rate of pure iron and nitriding sample is 2.19×10?5 mm3 /(N·m) and 1.06×10?5 mm3 /(N·m) respectively, with the wear rate of the nitriding sample about 50% lower than that of pure iron. Both deionized water and 3.5 wt.% NaCl solution were conducive to the reduction of the friction coefficient, but resulted in an increased wear rate. The wear rates of the pure iron and nitriding samples in the deionized water environment were 2.75×10?5 mm3 / (N·m) and 1.86×10?5 mm3 / (N·m), respectively, while in the 3.5 wt.% NaCl solution environment they were 3.5×10?5 mm3 / (N·m) and 2.28×10?5 mm3 / (N·m), respectively. The wear rate in the NaCl solution environment was significantly higher than in the other environments; under the synergistic effect of corrosion and wear, the material removal efficiency was higher. Having systematically studied the effect of salt-bath nitriding on the corrosion and wear properties of pure iron, theoretical guidance and technical support can be provided to improving the service life of electrical switch components in marine equipment.
Key words:  pure iron  salt-bath nitriding  corrosion  wear resistance  wear mechanism
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