Aluminum Anodizing Technology

About Aluminum Anodizing 4OH - 4e = 2H2O + O2

About Aluminum Anodizing      Products in aluminum or aluminum alloy for the anode placed in electrolyte solution, the use of electrolysis to the surface of alumina film formation process, known as the aluminum and anodized aluminum alloy. Anodized aluminum is essentially the principle of the principle of water electrolysis. When the current passed, will take place the following response:    In the cathode, the reaction according to the following release H2: 2H + +2 e ===H2    On the anode, 4OH - 4e ===2H2O + O2, the oxygen precipitation is not only a state of molecular oxygen (O2), also includes atomic oxygen (O), as well as the oxygen ions (O-2), usually in response to molecular oxygen that.     Aluminum as the anode was the last of the oxygen precipitation by oxidation, the formation of the anhydrous 12O3 membrane: 4A1 + 3O2 = 2A12O3 + 3351J It should be noted that not all oxygen generated role with the aluminum part in the form of gaseous precipitation.     The type of anodizing industry has long been widely used. Method known as many different names can be summarized in the following classifications:     By the current sub-types are: DC anodizing; AC anodizing; and thickness could be reduced to comply with the requirements of the production time, film thickness and uniformity of both dense and significantly improve corrosion resistance of the pulse current anodizing.     Divided by the electrolyte: sulfuric acid, oxalic acid, chromic acid, mixed acid and organic acid-based solution Sulfur salicylic natural colored anodizing.     According to the nature of the film are: ordinary film, hard-plasma membrane (thick film), ceramic membrane, light-modified layer, the semiconductor barrier layer, such as the role of the anodization.       DC sulfuric acid anodic oxidation of the most common, this is because it has applied to the majority of aluminum and anodized aluminum alloy; layer thick, hard and wear-resistant, sealing will be better after the corrosion resistance; colorless, transparent film, adsorption ability to easily coloring; deal with the lower voltage, less power consumption; do not have to change the voltage of the processing cycle is conducive to the practice of continuous operation of production and automation; sulfate than on the person against chromic acid in small, widely source , and low prices.     Over the past decade, China's construction industry and gradually the use of aluminum doors and windows and other decorative aluminum, and their surface treatment production lines and are based on this approach.     Anodic oxide film structure, the nature and application of    1) the structure of anodic oxide film by anodic oxidation film composed of two layers, a thick porous outer layer is the dielectric properties in a dense inner layer of the grown up, the latter known as the barrier layer (also known as the active layer) .    (1) Barrier layer barrier layer is composed of waterless A12O3, thin and compact, with high hardness and prevent the current through the role. (2) Of the outer layer of porous outer layer of porous oxide film is mainly amorphous A12O3 and a small amount of the r-A12O3.H2O also contains electrolyte anions.     The vast majority of the oxide film of good properties, such as corrosion resistance, wear resistance, absorption, insulation and other properties of porous outer layer by the thickness and porosity of the decision, but the two conditions but with the anodic oxidation is closely related to, it can be iodization conditions change to get use to meet the requirements of the different films. Thickness is the anodic oxidation products, one of the main performance indicators, and its value directly affects the size of the coating corrosion resistance, wear resistance, insulation and chemical coloring ability. In the conventional anodic oxidation process, the film increased with the thickening time. The maximum thickness in after, the extension of the processing time as gradually thinning, and some alloys such as A1-Mg, A1-Mg-Zn alloy is especially evident. Therefore, the oxidation time for the general control of the largest film thickness time.     2) The nature of anodic oxide film and application of anodic oxide film has high hardness and wear resistance, strong attachment capabilities, a strong adsorption capacity, good corrosion resistance and electrical insulation and high thermal insulation. As a result of these specific properties, so that in all respects a wide range of applications received.

Aluminum Anodizing Technology