Basic knowledge: anodic oxidation pretreatment process
aluminum alloy anodic oxidation pretreatment technology is a very important part in determining the quality of product appearance, material mechanical tattoo removal, sand, inferior smooth, whitening and other quality requirements are determined by the pretreatment process. The traditional pretreatment process is divided into three kinds: ( 1) Alkali corrosion process: the oil removal & rarr; Wash & rarr; Alkali corrosion & rarr; Wash & rarr; Wash & rarr; The light & rarr; Wash & rarr; Wash & rarr; Oxidation of aluminum processing is profile after degreasing, alkali corrosion treatment to remove hitches in alkali corrosion groove mechanical and natural oxidation film grain, sand, and then through the light tank to remove surface black ash, anodic oxidation can be achieved. The core of the technology process is alkali corrosion, the stand or fall of profile of the surface roughness, the sand are decided by the process. In order to achieve the purpose of leveling machine lines, usually takes 12 - alkali corrosion 15 minutes, aluminum consumption of 40 - 50 kg/T, alkali consumption of up to 50 kg/T. Such high aluminum consumption, waste of resources, and brings serious environmental problems, increase the cost of wastewater treatment. This technology has been used for over 100 years, the global most aluminum factory in use today, until nearly two years, only by acid erosion gradually replaced. （ 2) Pickling process: the oil removal & rarr; Wash & rarr; Pickling & rarr; Wash & rarr; Wash & rarr; Alkali corrosion & rarr; Wash & rarr; Wash & rarr; The light & rarr; Wash & rarr; Wash & rarr; Oxidation. Profile after oil removal after the first acid corrosion, alkali corrosion, a light, completed before processing. Core process is the acid corrosion of the process, to mechanical grain, sand and so on are determined by the acid corrosion. Different from alkali corrosion, acid corrosion is one of the biggest advantages to mechanical capability is strong, fast rise sand grain, aluminum consumption is low, usually 3 - 5 minutes to complete, aluminum consumption is almost 1/8 of the alkali corrosion, 1/6. From the perspective of the efficiency and save resources, acid corrosion is alkali corrosion process of a big step forward. Acid corrosion, however, more prominent environmental problem: acid tank of toxic gas escape of HF and pollution of water tank F ˉ. Fluoride is generally to be toxic, processing more difficult. In addition, after acid treatment, shaped hair black hair and dark appearance, aluminum processing while continued to alkali corrosion and the light, can brighten up some, but still very dark, both to increase the working procedure, and lose luster, so far no effective solutions to these questions. （ 3) Polishing process: the oil removal & rarr; Wash & rarr; Polishing & rarr; Wash & rarr; Washing, profile after oil removal in the polishing groove, namely by 2 - Five minutes after polishing, can form a mirror, after wash can be directly oxidized. The core of the technology process is polished, to grain, the mirror is done in polishing groove. Polishing possesses the advantages of aluminum consumption is low, profile light, but the polishing groove NOx escape, cause serious pollution of the environment and the operators of bodily injury, at the same time, the expensive chemical raw material costs and other factors but also restrain the process of the promotion. Throughout the three process, although have different characteristics, but the drawback is more outstanding, such as alkali corrosion of aluminum consumption is high, the more alkaline, work efficiency is low; Fluoride pollution acid corrosion, profiles, dark; High cost of polishing, severe pollution and so on. The process or polluting the environment, or waste of resources, aluminium or reduced the aluminum surface quality, urgently needed improvement process.