摘要
采用正交试验法对AZ91镁合金表面(La+Ce)双稀土转化膜进行了磷酸盐致密化工艺优化,并对比分析了基材和稀土转化膜致密化前后的耐腐蚀性能。结果表明,致密化工艺参数中对转化膜耐腐蚀性能的影响从大至小的顺序为:致密化温度>致密化时间>(NH4)3PO4浓度,正交极差分析结果优化得到的AZ91镁合金的最佳稀土转化膜致密化工艺为致密化温度45℃、致密化时为3min和(NH4)3PO4浓度6%;磷酸盐致密化处理后可在稀土转化膜表面形成CePO4、Mg3(PO4)2和LaPO4相,并对致密化处理前的(La+Ce)双稀土转化膜表面的裂纹/孔洞缺陷进行填补和修复;析氢腐蚀、电化学阻抗谱和极化曲线测试结果相吻合,即3种试样的耐腐蚀性能从高至低顺序为:致密化后的试样>致密化前的试样>空白试样,即(La+Ce)双稀土转化膜可以对AZ91镁合金起到保护作用,且经过磷酸盐致密化处理后试样的耐腐蚀性能会进一步提高。
The surfaces of AZ91 Mg-alloy,an advance sports equipment material,were modified with La/Ce conversion coatings grown via chemical route and densified in(NH4)3PO4 solution.The influence of the La/Ce-coating and densification conditions on the tribological behavior of AZ91-alloy was investigated with X-ray diffraction,scanning electron microscopy,electrochemical station and orthogonal test.The results show that the La/Ce-coatings and densification conditions all had a major impact.For example,a descending order of corrosion resistance exists:densified La/Ce-coatings>La/Ce-coatings>AZ91-alloy;and another descending order of impact factor can be listed:densification-temperature>densification-time>(NH4)3PO4-concentration.The optimized conditions included:a temperature of 45℃,a time of 3 min and a concentration of 6%.Moreover,phosphate densification significantly improved the compactness via decreasing the size/density of pores/cracks,and further enhanced the corrosion resistance because CePO4/Mg3(PO4)2/LaPO4 phases formed,possibly in pores and voids of La/Ce conversion coatings.
作者
张战锋
刘志成
付春峰
Zhang Zhanfeng;Liu Zhicheng;Fu Chunfeng(Shaanxi Vocational and Technical College,Xi’an 710038,China;Xi’an Jiaotong University,Xi’an 710061,China;Xi’an University of Architecture and Technology,Xi’an 710054,China)
出处
《真空科学与技术学报》
EI
CAS
CSCD
北大核心
2020年第2期163-168,共6页
Chinese Journal of Vacuum Science and Technology
基金
国家自然科学基金资助项目(51475460)
陕西省自然科学基金(2018JM7320).
关键词
AZ91镁合金
稀土转化膜
致密化
耐蚀性能
AZ91 magnesium alloy
Rare earth conversion coating
Densification
Corrosion resistance
