How to Anodize the Paper Towel Frame
In the first short time, the anodic oxidation treatment of the surface of aluminium profile paper towel holder can be uniformly oxidized to form a very thin and dense film. Due to the effect of sulfuric acid solution, the weakness of the film reacts partially, resulting in a lot of voids. The surface treatment of direct current sulfuric acid anodization mainly includes ceramic anodization, chromic acid anodization, oxalic acid anodization and hard anodization. There are two layers of anodic oxide film on the surface of aluminium alloy paper towel rack. The inner layer is also called barrier layer or active layer. The structure of the film is straight tubular. The bee prism formed by the interface between the oxide film and the metal is called cell. In fact, the whole film is composed of many crystal cells. The porous outer layer of the oxide film also contains a small amount of hydrate and cations of electrolyte, which have high hardness and the effect of blocking current passage. The growth condition of anodic oxide film on the surface of aluminium alloy paper towel holder is that the electrolyte can dissolve the oxide film. Anodic oxidation treatment of aluminium alloy towel holder can be divided into communication anodic oxidation, direct current anodic oxidation and pulse current anodic oxidation according to current method. The surface treatment of aluminium alloy paper towel rack electrolyte can be divided into oxalic acid, sulfuric acid, chromic acid and mixed acid. According to the membrane layer, it can be divided into general membrane, hard membrane, ceramic membrane and so on. Aluminum alloy paper towel holder shell is anodized in electrolytic solution, making full use of its strong electrolytic force, so that its surface constitutes a process of membrane structure, known as anodic oxidation treatment. Anodic oxidation treatment is divided into cathode and anode, cathodic oxidation electrolysis stability is high, when the current passes, hydrogen appears; Anodic oxidation contains atomic oxygen and ionic oxygen, some of which are embodied by gaseous methods.
1. Oxalic acid anodic oxidation on the surface of aluminium profile paper towel holder: the film obtained by communication electrooxidation is softer and less elastic than that by direct current under the same conditions; pitting is easy to occur by direct current electrooxidation, and can be prevented by choosing communication electrooxidation. With the addition of communication components, the corrosion resistance of the film improves, but the color deepens and the color uptake is worse than that of sulfuric acid film. 。 Direct current anodization uses lead, graphite or stainless steel as cathode. Its area ratio to the anode is (1:2) - (1:1). Oxalic acid is a weak acid with low solubility. When aluminium is oxidized, it is necessary to cool products and electrolytes. The thickness and color of oxalic acid film vary according to the composition of the alloy. The thickness of pure aluminium film is yellowish or silver white, while that of the alloy film is as thin as yellow and brass. After oxidation, the film can be cleaned and sealed for 30-60 minutes by steam with 4-power Pa pressure of 3.43 *10 without dyeing. The concentration of free oxalic acid in the electrolyte is 3%-10%, generally 3%-5%. In the oxidation process, the consumption of oxalic acid is about 0.13-0.14 g per A? H. Aluminum with 0.08-0.09g per A? H dissolves in the electrolyte to produce aluminium oxalate, which consumes 5 times the amount of aluminium. The concentration of aluminium ion in the solution is controlled below 20 g/L, and the solution will fail when containing 30 g/L aluminium. Oxalic acid electrolyte is very sensitive to chloride. When anodizing pure aluminium or aluminium alloy, the chloride content should not exceed 0.04-0.02g/L, and the solution should be made of pure water. As the temperature of electrolyte increases, the film becomes thinner. In order to obtain a thick film, the pH value of the solution should be improved. Most of the factors affecting sulfuric acid anodization are also applicable to oxalic acid anodization. DC, AC or DC can be used as the alternative for oxalic acid anodization.
2. Porcelain anodic oxidation on the surface of aluminium profile paper towel holder: The process of ceramic anodic oxidation treatment is basically the same as conventional sulfuric acid anodic oxidation. The difference is that the ceramic anodic oxidation is often mixed with electrolyte at high DC voltage (115-125V) and high solution temperature (50-60 degrees), and the pH value is often adjusted to keep it at 1.6-2 norms. Conditions within the perimeter are carried out. Porcelain anodic alumina and aluminium alloys are anodized in titanium, zirconium or thorium salts of oxalic acid, citric acid and boric acid solutions, and hydroxides of salt metals enter the oxide film pore in the solution, so that the surface of the products shows a treatment process with opaque and fine enamel or similar plastic appearance with special luster.
3. Anodic oxidation of thick film on the surface of aluminium profile paper towel holder: the maximum thickness of hard film can reach 250 um, the microhardness of the film formed on pure aluminium is 12000-15000 MPa, and the alloy is generally 4000-6000 MPa, which is almost the same as that of hard chromium coating. They have excellent wear resistance at low conformity, and the porosity of hard film is about 20%. It is lower than conventional sulfuric acid film. Hard anodic oxidation (HAO) is a process for producing thick and strong oxide films on the surface of aluminium and its alloys.
4. Chromic acid anodic oxidation on the surface of aluminium profile paper towel holder: the sulfate content in solution exceeds 0.5%, and the effect of anodic oxidation is not good. In most cases, barium hydroxide or barium carbonate can be added to sulfate ion to form barium sulfate precipitation. The chloride content in the solution should not exceed 0.2g/L. When the chromium content in solution exceeds 70 g/L, the solution should be diluted or replaced. The chromic acid anodizing process is shown in Table - 4. Concentration analysis should be often carried out in the oxidation process and chromium anhydride should be added in time. Lead, iron and stainless steel can be used as cathode data for electrolysis. The best positive-negative area ratio is (5:1) - (10:1). When there are more trivalent chromium ions in the solution, it can be oxidized to hexavalent chromium ions by electrolysis. There are two kinds of anodic oxidation methods with periodic variation of oxygen voltage in chromic acid anode, or constant voltage anodic oxidation method (fast chromic acid method).