Effect Of Temperature Gradient On The Performance Of Aluminum Alloy Hard Anodizing Film

The effect of temperature gradient on the performance of sulfuric acid hard anodizingfilm of6061Aluminum sheet was studied in this topic, which aimed at increasing filmthickness and hardness, at the same time, createing a new anodic oxide film generated theory.Because of its excellent properties, Aluminum alloy has the biggest usage and the widestapplication. However, Aluminum is very active and has more negative corrosion potential, itcorrodes easyer. Hence in order to expand the application range and extend service life,surface hardening is needed. Traditionally,low-temperature electrolyte is needed,which hashigh energy consumption and goes against environmental protection. What’s more, it is verydifficult to improve the mechanical properties of the oxide film. This topic, in the basis oftraditional theories,new understanding of the formation law of the oxide film form theoxidation of heat transfer and oxidation bubble, creating a model to guidetechnology,controlling the microsture of the flim,reducing porosity and improving thedensityof the oxide film,ultimately,the oxide film thickness and hardness increasedsignificantly.In this paper, effects of current density, coolant temperature and electrolyte temperatureparameters on oxide film film thickness, hardness and microtructure were studied. Andcomparing with traditional method. Scanning Electron Microscope (SEM) and computerimage analyzer microscope (XJP-6A) were used to analyze the microstructure of oxide film;Digital cladding thickness gauge (TT230) and computer display type manual turretmicro-hardness (MVC-1000JMT1) were applied to measure film thickness and hardness.According to the traditional theories, this paper discussed and analysed the experimentresults, which were as follows:(1) Compared with the oxidation heat transferred to the electrolyte through anodic film,the heat transferred to the coolant through aluminum substrate is more beneficial to thegrowth of anodic film.The obtained film with a thickness of60and a hardness of500HV,bothbetter than traditional methods.(2) Temperature gradient is more helpful to the growth of anodic film. Compared withoverall hard anodizing,thickness of film getting by temperature gradient method is thicker insame time. With time,more obvious differences between the oxide film thickness preared bytwo methods.Actual production,it can improdution efficiency.(3)The electrolyte temperature increased appropriately in temperature gradientmethod,mechanical properties of hard anodic oxide film is also good.Helping to reduceenergy and equipment spend.(4)Improving current density properly to accelelerate the generation rate of the filmobtaining by temperature gradient method.(5)The precipitation of oxygen bubbles,interacting with the temperature gradient,controlling the micro-organizations to improve the performance of the film.(6)It is very important of gas film coverage to chssse coolant temperature andelectorolysis temperature.Whatever,the bigger current density gave,the more bubble separatedout,the higher coverage was.So it should be a reasonable choice of the current density.