2A12 Aluminum Alloy Hard Anodic Oxidation Process And Composite Research Of Self Lubricating Film

Aluminum alloy has many excellent mechanical, physical and chemical properties, so there are used in various fields of national economy widely.But inherent in low-hardness and low wear resistance affect its application ranges and life-span.One of the main direction of the aluminum alloy research is improvig the surface performance with surface treatment technology.The aluminum alloy hard anodic oxidation process and the aluminum alloy hard anodic oxidation self-lubricating composite membrane preparation technology was studied systematically based on the 2A12 aluminum alloy as the main research materials. The research content mainly as following :(1)Used formula sulfate(adding glycerin 10 g/L) and process parameters commonly in hard anodic oxidation, through checking and examing layer thickness, hardness and surface morphology, the influence of sulfuric acid electrolyte concentration, current density and oxidation time to 2A12 aluminum alloy hard anodic oxidation film layer was studied.At the same time, the optimum process were confirmed with the Orthogonal Test which using the thickness and hardness as evaluation index.By the range analysis, the importance degree on the influence of film thickness of the different factors were developed. At last, through comprehensive analysis,to determine the hard anodic oxidation process both high hardness,good film thickness and small porosity on the surface.namely the electrolyte concentration 0.8 mol/L, the current density of 2.5A/dm2, time 2 h.(2)By adding solid solution in front of the hard anodic oxidation treatment process, testing and observating thickness and hardness of hard anodic oxidation film with different pretreatment processes2 a12 aluminum alloy after 475 ℃ and 505 ℃ solid solution treatment, solid solution plus 505 ℃ for 24 h and 505 ℃ when natural 48 h natural solid solution and aging),measuring the polarization curves in 3.5% nacl solution,and comparing layer of pure aluminium and not solid solution of aluminium alloy under the same hard anodic oxidation process, the influence of different heat treatment process on 2A12 aluminum alloy hard anodic oxidation were studied.The results show that:the anodized film thickness, hardness and corrosion resistancewere increase to some extent through increasing solid solution treatment process before hard anodizing technology of aluminum alloy 2A12.Under the same electrolyte solution and process parameters,2A12 aluminum alloy with 505 ℃ solution temperature compared with without solution treatment anodized film thickness and hardness from 48.61 um, 403.8 HV0.1, increased to 117.73 um, 602.7 HV0.1 respectively.the corrosion potential improving from 1.45 V to 1.45 V,and the log(I/A) of corrosion current from 6.42 to 9.39, and the quality of the film are greatly improved, membrane cell neat degree and the continuity of lattice configuration were significantly better than the no-solution sample.(3)In the process of aluminum alloy 2A12 anodic oxidation treatment by the optimum hard anodizing technology, the reaming process of the film in 5% phosphoric acid, temperature of40 ℃, reaming time 30 min, 40 min, 50 min,60 min, respectively are carried.Using solid lubricant inlaid graphite and molybdenum disulfide,respectively, by the method of soaking,soaking in ultrasonic field,and electrolytic deposition,the hard anodic oxidation of self-lubricating composite membrane preparation process was studied. and the coefficient of friction and the grinding crack morphology be observed and analyzed by using the friction testing machine and metallographic microscope respectively.The research of reaming proces that the aperture of porous anodic oxide film layer increasing as time expanding,but beyond a certain time,hole wall will be broken, and film hole caused by incomplete, the best time to expanding in50 min, the average pore diameter increased by 10 nm to 51 nm.Method test show that the friction coefficient of membrane layer can reduced effectively by depositing graphite and molybdenum disulfide in different sedimentary.The best effect is graphite electrolytic Mosaic which the friction coefficient is 0.1563,compared with 2A12 in 0.6459 and only hard anodic oxidation of aluminum alloy in 0.5423 was reduced by 75.8% and 71.1% respectively,the performance of friction materials improved effectively.The observation of grinding crack morphology showed that deep and wider furrows and adhesion wear characteristics of a few places have spalling appear on no-anodized aluminum alloy,the surface of the hard anodic oxidation sample furrows significantly thinner lighter, more smooth, and treated with graphite electrolytic Mosaic almost no obvious grinding marks on the sample surface.