摘要
目前，对镁合金表面恒功率微弧氧化的研究尚不够深入。在Na2SiO3-NaOH体系中，通过恒功率控制微弧氧化，在AZ91D镁合金表面获得了微弧氧化膜。分别利用SEM，EDS，XRD，硫酸铜点滴及NaCl浸泡腐蚀等方法分析了微孤氧化膜的形貌、成分、结构及耐蚀性能。结果表明：恒功率制备的微弧氧化膜由Mg，O，Si，Al元素组成，其物相主要由Mg，MgO，Mg，SiO4组成；在1～3kW功率内，随着功率的增加，膜层表面微孔数量减少，孔径增大，在含cl一溶液中的耐腐蚀性能变差；与恒压控制相比，恒功率控制使得镁合金微弧氧化初期在大电流下起弧，而后期是在高电压环境下进行，导致所形成的微弧氧化膜具有较少的微孔，但具有较大的孔径和较快的生长速度。
A micro-arc oxidation( MAO) coating was created on AZ91 D Mg alloy by constant power mode in a Na2 SiO 3-NaO H aqueous solution. The morpho-logy,element composition,phase structure and corrosion resistance were investigated by scanning electron microscopy( SEM),energy dispersive X-ray spectroscopy( EDS),X-ray diffraction( XRD),CuS O4 dropping corrosion test and a long time immersion test in a 3. 5% NaC l solution,respectively. Results showed that the MAO coating consisted of Mg,O,Al and Si,and its phase composition was Mg,MgO and Mg2 SiO 4. With the increase of the power from 1 to 3 kW,the coating exhibited poor corrosion resistance in Cl--containing solution due to the enlargement of the micro-pore sizes although the amount of the pores was decreased. Compared with the constant voltage mode,the constant power mode made the spark discharge easily appear under larger current density( or lower voltage) at the initial phase of the MAO process,and MAO process was going on under higher voltage( or lower current density) at the later period,which gave rise to the formation of MAO coating with few micro-pores,but with larger pore sizes and faster growth speed.
出处
《材料保护》
CAS
CSCD
北大核心
2015年第12期8-11,6,共4页
Materials Protection
基金
材料腐蚀与防护四川省重点实验室开放基金(2013CL01)
四川理工学院大学生创新基金(201410622022)资助
关键词
AZ91D镁合金
微弧氧化
恒功率
结构
耐蚀性
AZ91D magnesium alloy
micro-arc oxidation
constant power
structure
corrosion resistance
