激光功率对低碳钢表面激光熔覆钛合金涂层组织和性能的影响  

Effects of Laser Power on Microstructure and Properties of Titanium Alloy Coatings Prepared on Low Carbon Steel by Laser Cladding

作　　者：高炜 俞宏英 蒋旭洲 斯佳佳 孙冬柏 GAO Wei;YU Hong-ying;JIANG Xu-zhou;SI Jia-jia;SUN Dong-bai(School of Materials,Sun Yat-sen University,Guangdong Shenzhen 518107,China;School of Material Science and Engineering,Sun Yat-sen University,Guangzhou 510006,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Guangdong Zhuhai 519080,China)

机构地区：[1]中山大学材料学院,广东深圳518107 [2]中山大学材料科学与工程学院,广州510006 [3]南方海洋科学与工程广东省实验室(珠海),广东珠海519080

出　　处：《表面技术》2023年第3期246-254,265,共10页Surface Technology

基　　金：广东省促进经济高质量发展专项资金海洋经济发展项目(GDOE[2019]A16);南方海洋科学与工程广东省实验室(珠海)创新团队建设项目(311020012)。

摘　　要：目的利用激光熔覆简便、高效的特点,在低碳钢表面开发低成本、短流程的耐蚀钛合金涂层,拓宽钛合金在海洋工程装备上的应用。方法选择球形纯钛粉末,采用同步送粉式激光熔覆技术在低碳钢表面制备一层薄的钛合金涂层。通过单色红外测温仪对熔池的温度变化进行监测。利用光学显微镜(OM)、扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等表征涂层的宏观形貌、微观形貌和相组成。借助万能试验机和维氏硬度计测试涂层的结合强度、剪切强度和硬度。使用电化学工作站在NaCl(质量分数3.5%)溶液中测试涂层的极化曲线和阻抗(EIS),以评价涂层的耐蚀性能。结果采用激光熔覆技术在低碳钢表面成功制备了一层薄的耐蚀钛合金涂层。激光功率的选择对在低碳钢表面制备性能良好的钛合金涂层至关重要。一方面,激光功率会影响熔池的温度演变,随着功率的降低,熔池的最高温度降低,熔池寿命缩短。通过引入粉末沉积密度(ρPDD)和单位面积有效能量输入(Eeff)进一步描述工艺参数与涂层质量之间的关系。结果表明,在ρPDD(0.009 g/mm^(2))不变的情况下,要获得表面质量良好的涂层,需要将E_(eff)控制在一定范围(45~54 J/mm^(2))内。另一方面,激光功率会影响铁元素的热扩散,功率的增大会导致涂层表面的铁元素增多。由于铁元素在熔覆过程中的剧烈扩散,涂层的平均硬度皆大于400HV,预期对涂层的耐磨性能有正面影响。受到粉末束流对熔池的搅动作用,界面处形成了TiFe和Fe_(2)Ti的混合区域,此时涂层的结合强度降低。通过调控功率来减少涂层表面的铁元素含量,有利于提高涂层的耐蚀性能,P10涂层表面铁元素的含量最少,其自腐蚀电位最正(-0.298 V),自腐蚀电流密度(1.117×10^(-7)A/cm^(2))最低,EIS结果也进一步证实P10涂层具有良好的耐蚀性。结论选择合适的激光功率可以在�The work aims to take advantage of the simplicity and high efficiency of laser cladding to develop low cost,short process and corrosion resistant titanium alloy coatings on the surface of low carbon steel to broaden the application of titanium alloy in marine engineering equipment.With spherical pure titanium powder as raw material,a thin titanium alloy coating was prepared on the surface of low carbon steel by laser cladding.The temperature change of the molten pool during the cladding process was monitored by a monochromatic infrared thermometer.The macrostructure,microstructure and phase composition of the coating were characterized by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive spectrometer(EDS)and X-ray diffraction(XRD).The hardness,shear strength and adhesive strength of the coatings were measured by Wechsler hardness tester and universal testing machine,respectively.An electrochemical workstation was used to test the polarization curve and electrochemical impedance(EIS)of the coatings in 3.5wt.%Na Cl solution to evaluate the corrosion resistance of the coating.A thin corrosion resistant titanium alloy coating was successfully prepared on low carbon steel by laser cladding.The results showed that the laser power was critical for preparing excellent performance titanium alloy coatings on low carbon steel.On the one hand,the laser power affected the temperature change of the molten pool.With the decrease of the laser power,the maximum temperature and the lifetime of the molten pool decreased.The powder deposition density(ρPDD)and the effective energy per unit area(Eeff)were introduced to further describe the relationship between process parameters and the coating quality.When theρPDDwas constant(0.009 g/mm^(2)),it was necessary to control E_(eff)within a given range(45-54 J/mm^(2))to obtain a coating with good surface quality by changing the laser power.On the other hand,the laser power affected the thermal diffusion of iron,and the increase of laser power lead to the increase

关 键 词：激光熔覆 钛合金涂层 低碳钢 结合强度 耐蚀性能 海洋应用 

分 类 号：TG174.4[金属学及工艺—金属表面处理] TG665[金属学及工艺—金属学]