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| 离子铝氮复合渗对渗层组织性能的影响 |
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康前飞1,2, 魏坤霞1,2, 安旭龙1,2,3, 刘细良1,2,3, 赵芳利1,4, 胡静1,2,3
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1.常州大学江苏省材料表面科学与技术重点实验室 常州 213164;2.常州大学怀德学院 靖江 214500;3.常州大学材料科学与工程国家级实验教学示范中心 常州 213164;4.常州赛斐斯新材料科技有限公司 常州 213164
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| 摘要: |
| 为解决高温渗铝存在的基体组织粗化及离子渗氮效率低等问题，研发离子铝氮复合渗。以调质态 42CrMo 钢为材料， 先采用电解硝酸铝法在工件表面沉积氢氧化铝膜，然后进行离子渗氮处理，在不影响基体组织性能的前提下，研发离子铝氮复合渗创新技术。采用 SEM、光学显微镜、EDS、XRD、显微硬度计、电化学工作站、摩擦磨损测试机及三维轮廓仪等测试手段，对离子铝氮复合渗层进行测试分析。研究结果表明，离子铝氮复合渗处理后，试样表层高效形成多层次化合物渗层， 在(520 ℃ / 4 h)工艺条件下，化合物层由 17.24 μm 增加到 51.23 μm，提升约 3 倍；有效硬化层由 175 μm 增加到 1 050 μm， 提升约 6 倍。同时，化合物层中形成高硬度 AlN 及 FexAl 相；表面硬度由离子渗氮 750 HV0.025提高到 1 250 HV0.025；渗层耐蚀耐磨性比离子渗氮大幅度改善，腐蚀速率由 5.42 μm / a 降低到 1.23 μm / a；摩擦因数由 5.2 降低到 2.9，磨痕明显变窄变浅， 表面未有明显磨损裂纹。首次采用沉积氢氧化铝膜作为预处理，成功研发高性能离子铝氮复合渗技术。 |
| 关键词: 42CrMo 钢 离子铝氮复合渗 电解硝酸铝 离子渗氮 化合物层 |
| DOI：10.11933/j.issn.1007?9289.20220331003 |
| 分类号:TG178 |
| 基金项目:国家自然科学基金(21978025，51774052)、江苏省第三期优势学科建设项目(PAPD-3)、江苏高校品牌专业建设工程(TAPP)和江苏省研究生科研与实践创新计划(SJCX22_1327，KYCX22_2979)资助项目 |
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| Effect of Plasma Aluminum-nitriding on the Microstructure and Properties |
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KANG Qianfei1,2, WEI Kunxia1,2, AN Xulong1,2,3, LIU Xiliang1,2,3, ZHAO Fangli1,4, HU Jing1,2,3
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1.Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University,Changzhou 213164 , China;2.Huaide College, Changzhou University, Jingjiang 214500 , China;3.National Experimental Demonstration Center for Materials Science and Engineering,Changzhou University, Changzhou 213164 , China;4.Changzhou Surface Advanced Materials Technology Co., Ltd, Changzhou 213164 , China
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| Abstract: |
| Plasma nitriding (PN) is a widely used environment-friendly chemical heat treatment method that can improve the surface hardness and wear resistance of steel components. However, it has the disadvantages of low efficiency, and an insufficient surface hardness that fails to meet the demands certain severe applications. Aluminization is a surface modification technology that effectively improves the corrosion and oxidation resistance of various metals. Unfortunately, existing aluminizing methods are not environment-friendly and are generally performed at temperatures of up to 800 °C, which has a detrimental effect on the performance of the matrix. In this study, a plasma aluminum-nitriding (PAlN) method is proposed that utilizes the advantages and overcomes the disadvantages of both plasma nitriding and aluminizing. The PAlN method was developed for 42CrMo steel by depositing aluminum hydroxide films on the surface of the samples using the electrolytic aluminum nitrate method as a pretreatment to PN. The microstructures, phase constitutions, cross-sectional elements, hardness profile, and corrosion and wear resistance of the PAlN-treated samples were tested and analyzed by scanning electron microscopy, optical microscopy, X-ray diffraction, microhardness testing, and energy-dispersive X-ray spectroscopy. An electrochemical workstation, friction and wear tester, and 3D profilometer were also used. Aside from combining the advantages of aluminizing and PN, the PAlN method also has much better effects than expected, including behavior and efficiency. This is illustrated as 1 + 1 ＞ 2 owing to the formation of AlN with ultra-high hardness. The results showed that the PAlN layer rapidly formed on the surface of the sample. PAlN treatment at 520 ℃ for 4 h increased the compound layer from 17.24 μm to 51.23 μm, increasing the efficiency by approximately three times that of PN. The effective diffusion layer increased from 175 μm to 1050 μm, increasing the efficiency by approximately six times that of PN. AlN and FexAl phases with high hardness formed in the nitriding layer; the surface hardness increased from 750 HV0.025 to 1 250 HV0.025; and the corrosion and wear resistance significantly improved. The corrosion current decreased from 0.923 μA / cm2 to 0.220 μA / cm2 ; the corrosion potential increased from ?605.30 mV to ?299.58 mV; and the corrosion rate decreased from 5.42 μm / a to 1.23 μm / a. The friction coefficient decreased from 0.52 to 0.29. The wear marks became narrower and shallower, and no obvious wear cracks appeared on the surface. The potential mechanism is as follows. Active [Al] was formed by hydrogen [H] atoms sputtering the aluminum hydroxide film deposited on the surface of the sample, which enabled the active [Al] to easily combine with iron and nitrogen atoms to form FexAl and AlN. This resulted in not only ultra-high efficiency but also the excellent overall performance of the PAlN layer. In conclusion, the PAlN method with ultra-high efficiency and excellent performance was developed by depositing an aluminum hydroxide film on the surface of the samples using the electrolytic aluminum nitrate method as a pretreatment. This can be considered as the optimal surface modification technology to date. |
| Key words: 42CrMo steel plasma aluminum-nitriding electrolytic aluminum nitrate plasma nitriding nitriding layer |