Process Research And Mechanism Analysis Of Copper-manganese-silver Mixed Salt Aluminum Alloy Electrolysis To Golden Yellow

Aluminum alloy is a non-ferrous metal material with wide application and good comprehensive performance in construction,vehicles and machinery.In order to improve the corrosion resistance and aesthetics of aluminum alloy profiles,the surface treatment of aluminum alloys is often carried out by anodizing and electrolytic coloring processes.Among the many colors,Golden-Yellow is favored by the market for its solemn and beautiful features.At present,the aluminum alloy electrolysis process has the disadvantages of high cost,low efficiency,complicated technology and poor environmental protection.For this reason,this paper optimizes the existing permanganate aluminum alloy electrolysis golden yellow system by adjusting the electrolyte formulation and operating conditions,develops an environmentally friendly,fast,economical Cu-Mn-Ag mixed salt system without reaming,analyzes the electrolytic coloring mechanism.The details are as follows:The surface of the aluminum alloy was anodized by a sulfuric acid direct anodic oxidation method.The effects of oxidation time,oxidation temperature,oxidation voltage,sulfuric acid concentration and aluminum sulfate concentration on the thickness of oxide film were investigated by single factor experiment.The optimal sulfuric acid anodizing process was determined by the thickness of the oxide film.The specific process parameters were:oxidation time 50 min,oxidation temperature 25?,oxidation voltage 14 V,sulfuric acid concentration 200 g/L,and aluminum sulfate concentration 6 g/L.The thickness of the oxide film formed under this process condition was 44.2?m.After the sulfuric acid anodizing process,the aluminum alloy is colored by a two-step electrolytic coloring method.The effects of coloring time,temperature,voltage,sulfuric acid concentration,aluminum sulfate concentration,potassium permanganate concentration,copper sulfate concentration,silver nitrate concentration,on the appearance and corrosion resistance of colored film were investigated by single factor experiment.Under the appearance of the colored film is golden and non-defective,the optimal electrolytic coloring process is determined by the corrosion resistance of the colored film.The specific process parameters ware:coloring time 4 min,temperature 25?,voltage 7 V,boric acid concentration 5 g/L,aluminum sulfate concentration 10 g/L,sulfuric acid concentration 10g/L,potassium permanganate concentration 0.5 g/L,silver nitrate concentration 0.4 g/L,and copper sulfate concentration 1.0 g/L.The corrosion resistance test results of the colored film formed under this process condition was 136 s.The colored film produced by the Cu-Mn-Ag mixed salt electrolytic coloring technology in this paper is tested.The results show that the colored film has a golden color,uniformity,no apparent defects,and all the performance indicators were in accordance.There are pores with uniform distribution and similar size on the colored film,mainly contains oxygen,aluminum,sulfur,manganese,copper,silver,and exists the presence of amorphous coloring matter and crystalline state Mn₇O₁₃·5H₂O.The semiconductor theory and scattering principle are used to explain the coloring mechanism and color development mechanism of the aluminum alloy electrolysis process in this paper.It is proposed a mechanism model of reductive co-deposition that under the action of the promoter,the permanganate ion competes with copper ions and silver ions for binding electrons.This model explained the experimental process well.The conclusion is that the larger colored particles and the more amount of deposition,the darker the color of the colored film.The Cu-Mn-Ag mixed salt electrolytic coloring technology studied in this paper not only has the advantages of economical application,green environmental protection,efficient,simple process,convenient operation,etc.,but also has excellent product quality and performance,broad market application prospects.The Ag⁺,Cu²⁺,and MnO₄^-competitive deposition model has a promoting effect on the analysis and research of the electrolytic coloring mechanism of aluminum alloys.