Study On Processing Of Mirror Aluminum Sheets

Aluminum product is widely used in industrial and agricultural areas because of its rich reserves and a variety of excellent performance. The mirror aluminum products developed rapidly in recent years and have been widely used in various kinds of high-grade civil products. At present the main method to produce mirror surface aluminum is electro-polishing.In this paper, the main subject is to study the electrolytic polishing of1070,1085commercial pure aluminum and5N5high purity aluminum to obtain more reasonable polishing technology. Due to the fact that the polishing solution of HNO3and H2CrO4has a series of disadvantages such as severe pollution of environment, the HCIO4solution and H2SO4-H3PO4solution are chosen in the experiment. For every aluminum product, the electro-polishing is studied in both the two kinds of polishing solution. During the process of electro-polishing current density, polishing time and polishing temperature are changed to study the effect of processing parameters on polishing quality, so the optimal technology for electro-polishing of pure aluminum can be gained. Also the effect of purity of aluminum and sheets of rolled and annealed on the polishing quality is studied.Experimental results show that the purity of metallic material can affect the polishing quality. Compared with commercial aluminum,5N5high purity aluminum has better surface quality after polishing. For5N5high purity aluminum the reflectivity can reach98%and the surface cleanliness can be Grade I in the two solutions, and for1085commercial pure aluminum the reflectivity can reach90%and the surface cleanliness is Grade I in HCIO4solution. But the reflectivity can only reach85%in H2SO4-H3PO4solution. For1070commercial pure aluminum in the HCIO4solutions and1085in H2SO4-H3PO4solution can reach90%, but the surface cleanliness is Grade Ⅱ. The optimal electro-polishing showed that for1085commercial pure aluminum in HCIO4solution, current density is0.1～0.2A/cm, polishing time is10～12min, polishing temperature is5～15℃, and for5N5high purity aluminum in HCIO4solution, current density is0.2A/cm2, polishing time is22～28min, polishing temperature is5～10℃, and for5N5high purity aluminum in H2SO4solution, current density is0.2～0.4A/cm2, polishing time is15-35min, polishing temperature is85～95℃.(3) During the process of electro-polishing, defects such as white coating, pits sand surface flow marks can appear under unsuitable conditions of polishing technology, which can result in worse reflectivity and surface cleanliness.