Research On Key Technology Of Micro Arc Oxidation Of Titanium Alloy

AC7A as a new type of Al-Mg cast alloy, Because it has the characteristics of high elongation, machining and good corrosion resistance compared with other aluminum and magnesium alloys, it has been widely used in die making of tire industry. Micro-arc oxidation is a kind of emerging in situ at the valve metal surface generating a layer of ceramic coating on the surface modification technology, greatly improve the body of the film hardness and corrosion resistance performance, and the process on the environment more friendly, is increasingly extensive application in aerospace and automotive manufacturing and other fields. Micro-arc oxidation process involves multiple disciplines,into a film is a very complicated process, micro arc oxidation film hardness, wear resistance and corrosion resistance of although greatly improved but still can not meet the use conditions, prompted us to the need for more in-depth and comprehensive understanding of the research on micro arc oxidation process and the new processing method, electrolyte, electrical parameter optimization to improve the film performance.This paper mainly through orthogonal experiment, analysis and comparison of the effects of electric parameters on the properties of the coating; through the sample of AC7 A, the first composite pretreatment, ultrasonic-shot peening device is made into their sample, in different concentrations of Y（NO₃）₃ pretreatment solution of AC7 A Aluminum Alloy samples were pretreated by ultrasonic-shot peening, research the effects of film forming process and surface morphology, thickness of oxide film and the corrosion resistance of micro arc oxidation; at the same time put forward a new view of micro arc oxidation ceramic coatings sealing: ultrasonic rare earth sealing, micro arc oxidation ceramic layer AC7 A Aluminum Alloy studied by ultrasound after sealing the rare earth salt the surface morphology and corrosion resistance of the effect of the main content and conclusions are as follows:（1） establish the L₉（3⁴）orthogonal test table, selected thickness, surface roughness degree, the micro hardness as AC7 A aluminum alloy micro arc oxidation coating performance evaluation index, and through the comprehensive comparative analysis of the performance indexes of the ceramic layer of establishment of electrical parameters(current density, pulse frequency, duty ratio range of the optimal combination of value: when the current density is 20A/dm2 pulse frequency is 600 Hz, duty ratio is 10%, the comprehensive performance of the film to achieve the best. The influence of electrical parameters on the surface morphology and corrosion resistance of the coatings were studied.（2） Select the different concentrations of Y（NO₃）₃ solution as a pre processing solution on AC7 A aluminum alloy by ultrasonic-shot peening on pre processing, study the pretreatment solution Y（NO₃）₃ concentration on AC7 A Aluminum Alloy Microarc oxidation layer performance impact. Improve the performance of the composite preprocessing method improve the micro arc oxidation ceramic coating formation rate,reduces the energy consumed in the reaction process, in the appropriate pre processing solution concentration to make ceramic layer structure must be refined, more uniform,dense, corrosion resistance and hardness.（3） The Y₂O₃ solution as sealing liquid, and with ultrasound combined with on AC7 A aluminum alloy micro arc oxidation ceramic coatings sealing treatment, to study the influence of the sealing way on AC7 A aluminum alloy ceramic coating surface morphology, corrosion resistance and other properties.