It can be black dyed, but less decorative for other colors.Īnodized aluminum parts are commonly found in a wide range of applications, such as home appliances, sporting goods, electronics, architectural and aircraft components.ĭurability. Anodizing is a reacted finish that is integrated with the underlying aluminum. It is suited for applications of valves, sliding parts, gears, swivel joints, and so on. Hardcoat is specified for aluminum components subject to extreme wear applications where superior abrasion resistance is needed, or corrosive environments where a thicker, harder, more durable coating is necessary. Type III Sulfuric Acid Anodize, known as Type III, hard coat, hard anodizing, or engineered anodizing, the coatings are thicker than 25 μm. It is particularly suited for applications where hardness and resistance to abrasion are required. Also it is easy to be dyed with a variety of colors. Normally, the film thickness range from 1.8 μm to 25 μm, the overall thickness of the coating formed is 67 percent penetration in the substrate and 33 percent growth over the original dimension of the part. Type II Sulfuric Acid Anodize, it is the most common method for anodizing, and less expensive than other types of anodize concerning to chemicals used, heating, power consumption, and length of time to obtain the required thickness. It can be dyed in black, and not practical for other colors. It is good for tight tolerance parts or serves as a paint/prime base. Type I-Chromic Acid Anodize, it results in the thinnest anodic coat of the principal three types. The most common types of anodizing found in MIL-A-8625 are listed below: Sealing the anodized aluminum parts can be done in three ways: a cold method, a hot method, or a combination of the two. When lubrication properties are not critical, they are usually sealed after dyeing to increase corrosion resistance and dye retention. These pores can absorb dyes and retain lubricants but are also an avenue for corrosion. Acidic anodizing solutions produce pores in the anodized coating. Dyed anodizing is usually sealed to reduce or eliminate dye bleed out. The most common colors are yellow, green, blue, black, orange, purple and red. Depending on the chemical conditions of the bath and the length of time immersed, the aluminum color will vary. An electric current is applied to this bath as the metal salts oxidize in the aluminum’s pores. After immersing the anodized aluminum in an inorganic metal salt bath. The most common anodizing processes, for example, sulfuric acid on aluminum, produce a porous surface. The third step is color dyeing(if needed). The layer thickness can be more than 100 times as thick as an oxide layer, which would naturally exist on an aluminum part that is only exposed to oxygen. This results in an anodized aluminum layer growing on the surface of the part. When a current is passed through the electrolytic solution, hydrogen is released from the cathode(the negative electrode), and oxygen at the surface of the aluminum anode(the positive electrode), creating a build-up of aluminum oxide. The second step is that the aluminum part acts as the anode, then it is submerged in an electrolytic solution bath along with a cathode. The first step is to pre-treat the aluminum part through degreasing and pickling and providing a visibly smooth, clean surface.
0 Comments
Leave a Reply. |