Limitation of sulfuric acid anodizing on aluminum alloy

Limitation of sulfuric acid anodizing on aluminum alloy

1. The existence of alloy elements will reduce the quality of the oxide film. Under the same conditions, the oxide film on pure aluminum is the thickest, the hardness is the highest, the corrosion resistance is the best, and the uniformity is the best. Aluminum alloy material, in order to obtain good oxidation effect, to ensure the content of aluminum, usually not less than 95% is better.

2. In the alloy, copper will make the oxide film red, damage the quality of electrolyte and increase the oxidation defects; silicon will make the oxide film gray, especially when the content is more than 4.5%; because of its own characteristics, iron will exist in the form of black spots after anodizing.

Cast aluminum alloy

Casting aluminum alloy and die casting parts generally contain high silicon content, and the anodic oxide film is dark, so it is impossible to obtain colorless and transparent oxide film. With the increase of silicon content, the color of anodic oxide film changes from light gray to dark gray to black gray. Therefore, cast aluminum alloy is not suitable for anodizing.

The main classification and composition of commonly used die casting aluminum alloys are as follows:

The commonly used die casting aluminum alloys can be divided into three categories: the first is aluminum silicon alloy, which mainly includes yl102 (ADC1, a413.0, etc.), yl104 (adc3, a360); the second is aluminum silicon copper alloy, mainly including YL112 (A380, adc10), yl113 (A383, ADC12), yl117 (B390, adc14); the third is aluminum magnesium alloy, mainly including 302 (5180, adc5, adc6).

For Al Si alloy and Al Si Cu alloy, as the name implies, except for aluminum, silicon and copper are the main components; under normal circumstances, the content of silicon is between 6-12%, which mainly plays the role of improving the fluidity of alloy liquid; the copper content is only the second, which mainly plays the role of strengthening the strength and tensile force; the iron content is usually between 0.7% and 1.2%, within this proportion, The demoulding effect of the workpiece is the best; it can be seen from its composition that it is impossible to oxidize and color this kind of alloy, even if desiliconization oxidation is used, it is difficult to achieve the ideal effect. However, it is difficult to form oxide film on Al Si alloy or Al alloy with high copper content, and the film is dark, gray and poor gloss.

For Al Mg alloy, the oxide film is easy to form, the quality of the film is also better, it can be oxidized and colored, which is an important feature different from other alloys; however, there are some shortcomings in comparison.

Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing cathodic protection technology, engineering design, installation and technical services.