铝酸钠对铝合金微弧氧化膜层组织性能的影响

Effect of sodium aluminate on microstructure and properties of micro-arc oxidation coatings on aluminum alloy

对7050铝合金进行微弧氧化处理,研究不同NaAlO_(2)浓度对7050铝合金微弧氧化膜层物相组成、形貌、成分、厚度、硬度、粗糙度和耐蚀性能的影响。结果表明:膜层相主要由α-Al_(2)O_(3)相、γ-Al_(2)O_(3)相和Al相构成。膜层表面呈明显的“火山堆”形貌,随NaAlO_(2)浓度增加,“火山堆”体积不断增大,孔洞不断变大,裂纹不断增多、粗化。随NaAlO_(2)浓度增加,膜层厚度、粗糙度不断上升,硬度、耐蚀性先升后降。当NaAlO_(2)浓度为16 g/L时,膜层表面均匀、致密,合金获得最佳的综合性能,此时膜层的厚度、硬度、粗糙度、自腐蚀电流分别为28.8μm、1 138HV_(0.1)、2.477μm和8.02×10^(-7) A/cm^(2)。

7050 aluminum alloy was treated by micro‐arc oxidation.The effects of different NaAlO_(2) concentrations on the phase composition,morphology,composition,thickness,hardness,roughness and corrosion resistance of micro‐arc oxidation coatings on 7050 aluminum alloy were studied.The results show that,the main phases of coating were α‐Al_(2)O_(3) ,γ‐Al_(2)O_(3) and Al phase.The surface of the coating presents an obvious"volcanic pile"morphology,and with the increase of NaAlO_(2) concentration,the volume of"volcanic pile"continues to increase,the holes continue to grow,and the cracks continue to increase and coarsen.Meanwhile the thickness and roughness of the coating show an increasing trend,and the hardness increases firstly and then decreases.When the concentration of NaAlO_(2) is 16 g/L,the surface of the coating is uniform and compact,and the alloy obtains the best comprehensive properties.The thickness,hardness,roughness and self corrosion current of the coating are 28.8μm,1 138HV_(0.1),2.477μm and 8.02×10^(-7) A/cm^(2),respectively.