Prepare And Research On A Pulse Current Hard Anodic Oxidation Film For Aluminum-copper Alloy

Aluminum-copper alloy exhibits light weight, high mechanical strength, also this alloy tend to be used widely. In this dissertation, the development and research on the Aluminum-copper alloy are systematically presented, and then a set of equipment for hard anodizing at pulse current was auto-designed by the laboratory. The mechanical property, structure feature and morphology of the hard anodic oxidation film formed in electrolyte H₂SO₄ were investigated by eddy thickness gauge, micro-hardness tester, SEM and XRD.First of all, I simply introduced the common basic nature and development of aluminum and its alloys, and focused on the anodic oxide film growth process and the major influencing factors of aluminum and its alloys. The research on the topic of 2A12 aluminum alloy performance and chemical composition was introduced, and made briefly outlined preparation methods of the current commonly used 2A12 aluminum alloy anodic oxide film. A major research purposes and content of this subject were proposed. Then the characteristics of experimental materials and laboratory equipment of 2A12 aluminum alloy was described. The selected experimental methods and experimental route was highlighted. According to the enterprise's request for the property of the hard anodizing film of specimen, a set of equipment for hard anodizing at pulse current was auto-designed by the laboratory.In this paper various processing parameters (including current density,Voltage, oxidation time,temperature etc.) were studied, and reviewed the effects of every process conditions on the thickness, hardness, anti-erosion of oxidation coating, In the basis of Single component electrolyte experiment, using L₉ (3³ ) orthogonal experiment. The H2SO4 concentration used widespread was 28% as the base electrolyte, a good HAO composition of the electrolyte system for 2A12 aluminum alloy was found out: the base current I₁ was 2A, pulse current I₂ was 4A, the rising time and falling time of the trapezoidal pulse were 5 s, pulse forms can be adjusted at random, current density was 4A/dm², electrolyte temperature was—8℃, oxidation time was 90min, The thickness of the hard anodizing film was greater than 30μm, the highest thickness was up to 40μm and the micro-hardness was greater than 350 HV.This paper has analyzed the surface and cross-section morphology and the phase composition of the ceramic coatings by using SEM, XRD. The results show that coatings mainly contain Al₂O₃, and are composed of the two-layer structure with barrier layer and porous layer. The substrate and coating penetrate each other, presenting metallurgy combination. At the same time inspected micro-oxidation of the ceramic film thickness, the bond strength etc.