摘要
为了推动低成本高效能的无铬ZnAl涂层在NdFeB永磁体表面的防护应用,采用SEM、TR300轮廓仪等设备对比了NdFeB永磁体基体经过不同预处理工艺(碱洗、酸洗、喷砂、喷砂+酸洗)对NdFeB永磁体表面涂覆无铬ZnAl涂层的结合强度和耐蚀性能的影响。结果表明:喷砂与喷砂+酸洗(5 s)均能明显增加无铬ZnAl涂层与基材的结合强度;NdFeB永磁体基体经过碱洗后涂覆ZnAl涂层的耐硝酸铵浸泡腐蚀抗力最强(达230 min);喷砂及喷砂+酸洗(5 s)预处理可以增大基体表面粗糙度,有助于增加涂液和基体的接触面积,增强涂层与基体的结合力,但喷砂过程中砂粒的高速冲击会造成基体表面发生破坏,导致无铬ZnAl涂层的耐蚀性不及基体碱洗预处理后涂层的;酸洗(50 s)预处理后ZnAl涂层的耐蚀性显著下降。因此低损伤、环境友好的碱洗处理为在烧结NdFeB表面涂覆ZnAl涂层时对基体的最佳预处理方法。
In order to promote the application of low-cost and high-performance chromium-free ZnAl coating in the protection of NdFeB permanent magnet,the effects of different pretreatment processes(alkali washing,pickling,sandblasting,sandblasting+pickling)on the adhesive strength and corrosion resistance of chromium-free ZnAl coating prepared on the surface of NdFeB permanent magnet were studied using SEM and TR300 profilometer.Results showed that both sandblasting and sandblasting+pickling(5 s)could significantly increase the adhesive strength between the chromium-free ZnAl coating and the NdFeB substrate;the ZnAl coating prepared after an alkali washing had the strongest corrosion resistance to the ammonium nitrate immersion(up to 230 min).The pretreatment processes of sandblasting and sandblasting+acid pickling(5 s)could increase the surface roughness of the substrate and enlarge the contact area of ZnAl coating solution with the substrate surface to enhance the adhesive strength,but the corrosion resistance of the coating was far lower than that of the coating treated with alkali washing due to the damage to the substrate surface caused by the high-speed impact of sand particles during sandblasting.After the substrate was pretreated with pickling(50 s),the corrosion resistance of the coating was greatly reduced.Therefore,as a low-damage and environmental friendly pretreatment process,alkali washing was the best pretreatment for ZnAl coating prepared on sintered NdFeB surface.
作者
曹苗
谢发勤
吴向清
王少青
鲁闯
姚小飞
CAO Miao;XIE Fa-qin;WU Xiang-qing;WANG Shao-qing;LU Chuang;YAO Xiao-fei(School of Civil Aviation,Northwestern Polytechnical University,Xi'an 710072,China;Ningbo Polytechnic,Ningbo 315800,China;School of Materials and Chemical Engineering,Northwestern Polytechnical University,Xi'an 710072,China)
出处
《材料保护》
CAS
CSCD
2022年第8期109-116,124,共9页
Materials Protection
基金
宁波市“科技创新2025”重大专项(2019B10095)资助。
关键词
无铬ZnAl涂层
NDFEB永磁体
预处理
结合力
耐蚀性
chromium-free ZnAl coating
NdFeB permanent magnet
pretreatment
adhesive strength
corrosion resistance
