| Aluminium and its alloys anodic oxidation which have high hardness, high wear resistance, excellent coloring and other superior performance, has been widely applied in daily life, aerospace, electronic materials and national defense industry and other fields. Anodic oxidation is a very effective method to improve aluminum and its alloy corrosion resistant performance, Surface film obtained by anodic oxidation process by simple equipments, less investment, without changing the base metal properties and dimensions. Aluminum and its alloy anodic oxidation electrolyte has fixed, It has become the focus of current research and development for improve the performance of film layer by adding additive.In this paper,use sulfuric acid as the basis electrolyte,6063aluminum alloy as base material, The rare earth modified anodic oxidation film were made by adding La3+and Ce3+ions in the electrolyte during the single pulse electroplating. The oxidation film hardness, corrosion resistance, surface morphology, microstructure and composition of rare earth modified anodic oxidation film and normal oxidation film were tested and analyed. CeCl3hole sealing, boiling water hole sealing, high concentrations K2Cr2O7hole sealing, low concentration K2Cr2O7hole sealing, Ni2+sealing hole and Ni2+-Co2+sealing hole of the optimal modification oxide film, and the corrosion resistant performance, microstructure and composition of each hole sealing way were compared.Five factors as sulfuric acid concentration, voltage, time, glycerol concentration and oxalic acid concentration are selected to carry out the orthogonal experiment with five factors four levels. The oxidation films’ Tafel corrosion potential in3.5%NaCl solution of room temperature were choosed as the orthogonal experiment criteria, and then the best parameters were determined by the anti-corrosion property in the orthogonal experiment, they are sulfuric acid108ml/L, voltage12V, Time1.5h, glycerol8ml/L, oxalic acid12g/L. And on those parameter basis, The rare earth modified oxidation film has the best corrosion resistance which is0.5g/L CeCl3+0.5g/L LaCl3, It is214mg/dm2in phosphor-chromic acid corrosion weightlessness, only1/5of the common oxide film; It’s surface vickers hardness is2times to6063aluminum alloy; The scanning electron microscopy (SEM) was used to observe the surface morphology of rare earth modified oxidation film, and it was found that the surface of rare earth modified oxidation film are more smooth, the organization are more compact and uniform, the film hole diameter is small, the average diameter is3nm; It’s corrosion potential is0.8134V, extreme polarization current density is2.4×10-7A/cm2; At the same time, the energy dispersive spectrum (EDS) analysis showed that no rare earth element in the rare earth modified oxidation film.Hole sealing to rare earth composite modification anodic oxide film, Tests showed that the hole sealing liquid with3g/L CeCl3·7H2O,0.5g/L H3BO3,0.3ml/L H2O20.3ml/L hole sealing film has excellent corrosion resistance, It is28.4mg/dm2in phosphor-chromic acid corrosion weightlessness; It’s corrosion potential is0.5134V, extreme polarization current density is8.85×10-8A/cm2; The scanning electron microscopy (SEM) was used to observe the surface morphology of hole sealing film, and it was found that it is small granular and smooth, and its stable chemical performance, good resistance to corrosion; At the same time, the energy dispersive spectrum (EDS) analysis showed that Ce mass fraction is54.2%, the atomic number is19%.This topic shows that rare earth element is added in the electrolyte can effectively improve the corrosion resistance performance of aluminum anode oxide film, cerium salt sealing hole method is a kind green hole sealing of environmental protection, little energy consumption, the operation simple, effective way. |
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