摘要
目的研究电流密度对陶瓷膜层厚度、硬度及耐磨、耐腐蚀性能的影响。方法在含有氢氧化钠和硅酸钠的电解液中添加石墨烯纳米片(GNPs),采用脉冲直流模式实现不同电流密度条件下2024铝合金的微弧氧化(MAO)处理。采用扫描电镜(SEM)和能谱仪(EDS)对膜层形貌和成分进行了分析,借助电化学极化曲线测试了膜层的耐腐蚀性能,使用X射线衍射仪(XRD)表征了试样的相组成,利用多功能材料表面性能试验机测定了陶瓷膜表面力学性能。结果电流密度从1 A/dm^2增加到5 A/dm^2时,含GNPs的陶瓷膜层厚度由4.2μm增加到5.8μm,不含GNPs的膜层厚度由2.7μm增加到4.5μm。电流密度为1 A/dm^2时,含GNPs的膜层硬度达到163 HV,比同电流密度下不含GNPs的膜层硬度提高63%。电流密度为1 A/dm^2时,摩擦系数约为0.5;电流密度达到5 A/dm^2时,摩擦系数降低为0.3,膜层的耐磨性能提高。电流密度为3 A/dm^2时,自腐蚀电位开始逐渐升高,而自腐蚀电流呈下降趋势,生成的陶瓷膜的耐蚀性最好。电流密度对陶瓷膜成分的影响不明显。结论试样致密层的摩擦系数随电流密度的增大而显著降低,耐磨性能提高。提高电流密度可有效减少膜层上放电孔洞的数量和尺寸,改善膜层的耐蚀性,电流密度达到3 A/dm^2时,膜层的耐蚀性能最佳。引入GNPs可提高膜层的厚度、硬度、耐磨性能、耐腐蚀性能。
The work aims to study effects of current density on thickness,hardness and wear resistance,corrosion resistance of MAO coating.Graphene nanoplatelets(GNPs)was added to the electrolyte containing sodium hydroxide and sodium silicate,micro-arc oxidation(MAO)treatment of 2024 aluminum alloy was completed at different current density in the mode of pulsed direct current.Morphology and composition of the coating were analyzed using scanning electron microscope(SEM)and energy dispersive spectrometer(EDS);corrosion resistance of the coating was tested using polarization curve;phase composition of the sample was characterized with X-ray diffractometer(XRD);surface mechanical property of the ceramic coating was determined with multi-functional material surface performance testing machine.Current density increased from 1 A/dm2 to 5 A/dm2,thickness of coating containing GNPs increased from 4.2μm to 5.8μm,thickness of GNPs-free coating increased from 2.7μm to 4.5μm.After MAO treatment at initial current density of 1 A/dm2,the hardness of the coating containing GNPs was up to 163HV,63%higher than that of GNPs-free coating.Friction coefficient was about 0.5 when current density was 1 A/dm2,and it decreased to 0.3 as current density reached 5 A/dm2,which improved wear resistance of coatings.At the current density of 3 A/dm2,self-corrosion potential increased gradually,and corrosion current tended to decrease,and corrosion resistance of the ceramic coating was the best.Current density had no obvious effects on composition of the ceramic coating.Friction coefficient of compact layer in the sample significantly decreases and wear resistance improves as current density increases.Higher current density can effectively reduce number and size of discharge holes on the coating,and improve corrosion resistance of the coating.The coating exhibits the best corrosion resistance at the current density of 3 A/dm2.Thickness,hardness,abrasive resistance and corrosion resistance of the coating can be improved by adding GNPs.
作者
唐誉豪
向东
李东豪
王雷
王平
韩培冬
TANG Yu-hao;XIANG Dong;LI Dong-hao;WANG Lei;WANG Ping;HAN Pei-dong(School of Material Science and Enginering,Southwest Petroleum University,Chengdu 610500,China;Southwest Institute of Electronic Telecommunication Technology,Chengdu 610041,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2018年第7期203-208,共6页
Surface Technology
基金
四川省国际科技合作与交流研发项目(2017HH0086)
西南石油大学第17期开放实验重点项目(KSZ17121)~~
关键词
2024铝合金
微弧氧化
电流密度
石墨烯
硬度
耐磨性
耐蚀性
2024 aluminum alloy
micro-arc oxidation
current density
graphene
hardness
abrasive resistance
corrosion resistance
