热处理对电沉积纳米晶铬镀层微观结构及耐蚀性的影响  

Effect of Heat Treatment on Microstructure and Corrosion Resistance of Electrodeposited Nanocrystalline Chromium Coating

作　　者：王心悦 王吉会[1] 高志明[1] 夏大海 胡文彬[1] WANG Xin-yue;WANG Ji-hui;GAO Zhi-ming;XIA Da-hai;HU Wen-bin(Tianjin Key Laboratory of Composite&Functional Materials,School of Materials Science and Engineering,Tianjin University,Tianjin 300350,China)

机构地区：[1]天津大学材料科学与工程学院天津市材料复合与功能化重点实验室

出　　处：《表面技术》2019年第12期59-67,共9页Surface Technology

基　　金：天津市支撑计划项目(16YFZCGX00100);天津市科技计划项目(18YFZCGX00050);国家自然科学基金(51671144,51871164);山东省泰山产业领军人才工程项目(SF1503302301)~~

摘　　要：目的改善H13钢表面纳米晶Cr镀层的微观结构和耐腐蚀性能。方法利用电沉积技术在H13钢表面制备纳米晶Cr镀层,并通过调整热处理工艺调控Cr镀层的结构和性能。通过扫描电子显微镜(SEM)、原子力显微镜(AFM)和X射线衍射仪(XRD)、维氏显微硬度计和中性盐雾试验(NSS)研究了不同热处理工艺下Cr镀层的表面形貌、粗糙度、相结构、硬度及耐蚀性。结果采用电沉积技术成功在H13钢表面制备出体心立方结构的纳米晶铬镀层,其晶粒和微裂纹尺寸随着热处理温度(200~600℃)和保温时间(1~2h)的增加而增大。当热处理温度达到400℃时,镀层表面检测到Cr2O3氧化层,并随着热处理温度和保温时间的增加,氧化程度逐渐增大。此外,Cr镀层硬度随着热处理温度和保温时间的增加而逐渐降低。在600℃下保温2h后,镀层硬度为(499.8±9.3)HV0.2,与镀态((749.0±13.2)HV0.2)相比,大约下降了33%。然而,经500℃和600℃热处理的镀层具有最好的耐蚀性能,盐雾试验后,镀层表面未见明显腐蚀缺陷,保护评级为10级。结论随着热处理温度和保温时间的增加,镀层晶粒变大,表面氧化程度加剧,耐蚀性能显著增强。The work aims to improve the microstructure and corrosion resistance of nanocrystalline chromium coating on H13 steel.Nanocrystalline chromium coating was prepared on H13 steel by electrodeposition technique.Heat treatment was applied to control the microstructure and corrosion resistance of coating.The surface morphology,roughness,phase structure,microhardness and corrosion resistance of the chromium coating were investigated by scanning electron microscopy(SEM),atomic force microscope(AFM),X-ray diffractometer(XRD),Vickers microhardness tester and neutral salt spray test(NSS),respectively.Nanocrystalline chromium coating with body-centered cubic structure was successfully prepared on the surface of H13 steel by electrodeposition technique.The size of grains and microcracks increased with the increase of heat treatment temperature(200~600℃)and duration(1~2 h).When the heat treatment temperature reached 400℃,Cr2 O3 oxide layer was detected on the surface of Cr coating,and the degree of oxidation increased with the increase of the heat treatment temperature and duration.In addition,the hardness of Cr coating decreased with the increase of heat treatment temperature and duration.After the heat treatment at 600℃for 2 h,the microhardness of the coating was about(499.8±9.3)HV0.2,which decreased by 33%compared with that of the as-plated coating((749.0±13.2)HV0.2).However,the coatings with the best corrosion resistance were obtained after heat treatment at 500℃and 600℃and no obvious corrosion defects were found on the coating after salt spray test,and the protection rating was 10.With the increase of heat treatment temperature and duration,the grain size and the degree of the surface oxidation increase,thereby enhancing the corrosion resistance of the coating.

关 键 词：Cr镀层 电沉积 热处理 组织结构 耐蚀性 

分 类 号：TQ153.2[化学工程—电化学工业]