Study On Anodized Pretreatment Of Aluminum Alloy

In the process of anodized process,pretreatment occupies a very important position,the quality of pretreatment is directly related to the quality of later anodic oxidation.The micromorphology of the samples was tested by a shape measurement laser microscopy system and SEM.The roughness of the sample surface was tested by a handheld surface roughness instrument or shape measurement laser microscopy system.The surface gloss of the sample was tested using a gloss meter.The sample surface color teseted by using a color differential instrument.The main research results are as follows:The surface gloss of aluminum alloy decreases,the roughness increases,the brightness increases and becomes more green and blue after alkaline etching.With the increase of alkaline etching temperature and concentration,the alkaline etching reaction becomes more and more intense.The reaction becomes more intense when the alkaline etching solution does not contain aluminum ions.The more severe the alkaline etching reaction,the greater the gloss decline and roughness increase.When the alkaline etching temperature is 50℃,Na OH is 50 g/L,and Al³⁺is 30 g/L,the gloss is decreased by14.8GU,and the roughness is increased by 0.069μm.The gloss decreases greatly,the roughness increases,the lightness decreases and changes in the direction of turning green and yellow after anodizing.The anodized film without alkaline etching has less glossy,and the film thickness is larger.The surface gloss of aluminum alloy increases,the roughness decreases,the brightness increases and becomes more green and blue after chemical polishing.Chemical polishing treatment can effectively cut the height of scratches,but it will leave small hemp spots on the matrix surface.Chemical polishing treatment can effectively cut the height of scratches.The polishing time of phosphosulfuric acid is shortened,and the roughness reduction ranges from 0.074 to 0.142μm.The roughness of changing the sulfuric acid to acetic acid in the two-side acid polishing solution is reduced by 0.025 to 0.103μm.Reducing the polishing temperature,adding oxalic acid,citric acid,tartaric acid,glacial acetic acid to the phosphosulfuric acid solution can improve the surface roughness reduction range.It works best when the 10 g/L of citric acid is added,with the roughness being reduced by 0.110μm and the gloss being increasing by 20.7GUThe roughness values of 120#,240#,320#,400#,600#and 800#sandpaper grinding samples are in the range of 0.009 to 0.240μm.And the surfacet when the last sandpaper is 800#and then grinded by wool felt can reach the mirror luster.The roughness of 120#～600#sandpaper grinding samples increase after alkaline etching and anodic oxidation and decrease after chemical polishing.The magnitude of the change decreases as the sandpaper number increases.After sealing,the roughness of 120#and240#sandpaper grinding samples decrease,and the roughness of 320#,400#and 600#sandpaper grinding samples increases.The minimum roughness is 1.000μm and the maximum is 2.048μm.The roughness of 800#sandpaper polished sample increases after each anodizing treatment.