HVAF喷涂超细WC-10Co-4Cr粉末涂层的耐腐蚀性研究  

Study on Corrosion Resistance of HVAF Sprayed Ultra-thin WC-10Co-4Cr Coatings

作　　者：黄伟[1] 张建普[2] 王伟[2] 李定骏[2] 王斌[1] 巩秀芳[2] 聂丽萍[2] 吴比[2] Huang Wei;Zhang Jianpu;Wang Wei;Li Dingjun;Wang Bin;Gong Xiufang;Nie Liping;Wu Bi(School of new energy and materials,Southwest Petroleum University,Chengdu 610500;Material research center/Surface Engineering Research Institute of Dongfang Electric Group Dongfang Steam Turbine Co.,Ltd,Deyang 618000)

机构地区：[1]西南石油大学新能源与材料学院,成都610500 [2]东方电气集团东方汽轮机有限公司材料研究中心/表面工程研究所,德阳618000

出　　处：《热喷涂技术》2022年第1期46-54,共9页Thermal Spray Technology

基　　金：国家重点研发计划(2020YFB20104);四川省软科学研究计划项目资助(2020JDR0383)。

摘　　要：对比研究超细和常规粒度WC-10Co4Cr粉末喷涂制备涂层的性能,根据显微形貌、力学性能与电化学特性比较两种涂层的耐腐蚀性并分析机理。在304不锈钢基体上,利用空气助燃高速(High Velocity Air Fuel,HVAF)热喷涂技术制备WC-10Co-4Cr涂层。采用SEM和XRD分析了涂层的物相组成和显微形貌,采用维氏硬度仪和万能拉伸试验机分别测试了涂层的显微硬度与结合强度以表征力学性能,在质量分数为3.5%的NaCl溶液中对涂层进行电化学分析。结果表明:两种WC-10Co-4Cr粉末涂层均具有优异的耐腐蚀性能,超细粉末涂层自腐蚀电位(-0.199 V)高于常规粉末粒径涂层(-0.267 V);超细粉末粒径涂层腐蚀电流密度(1.996×10^(-7)A/cm^(2))小于常规粉末粒径涂层(3.123×10^(-6)A/cm^(2)),对基体能起到良好的保护作用。超细粉末与常规粉末WC-10Co-4Cr涂层电位腐蚀的机理主要是WC与粘结相的电偶腐蚀、Cl-对涂层表面钝化膜的破坏引起的孔蚀,腐蚀机理基本一致,主要差异在于,超细粉末涂层的致密度更高,组织更加均匀提高了涂层的耐腐蚀性。The performance of ultrafine and conventional WC-10Co-4Cr coatings was investigated.The corrosion resistance of the two coatings was compared according to the microscopic morphology,mechanical properties and electrochemical properties,and the mechanism was analyzed.WC-10Co-4Cr coating was deposited by High Velocity Air Fuel(HVAF)thermal spraying on 304 stainless steel substrate.The phase composition and micromorphology of the coating were analyzed by SEM and XRD.The microhardness and bonding strength of the coating were tested by Vickers hardness tester and universal tensile testing machine respectively to characterize the mechanical properties of the coating.Electrochemical analysis was performed on the coating in 3.5%NaCl solution.The results showed that the two kinds of WC-10CO-4Cr powder coatings exhibited excellent corrosion resistance,and the self-corrosion potential of the ultrafine powder coating(-0.199 V)was higher than that of the conventional powder particle size coating(-0.267 V).The corrosion current density of ultrafine powder coating(1.996×10^(-7) A/cm^(2))was lower than that of conventional powder coating(3.123×10^(-6) A/cm^(2)),which can protect the substrate well.The mechanism of potential corrosion of ultrafine powder and conventional powder WC-10CO-4Cr coating was mainly the galvanic corrosion of WC and bonding phase and the pitting corrosion caused by Cl-damage to the passive film on the coating surface.The corrosion mechanisms were basically the same.The main difference of corrosion resistance was that the higher density and more uniform microstructure of ultrafine powder coating,which improved the corrosion resistance of coating.

关 键 词：空气助燃高速热喷涂(HVAF) 超细WC-10Co-4Cr粉末 涂层 组织性能 电化学特性 

分 类 号：TG174.4[金属学及工艺—金属表面处理]