Hardcoat anodizing

Hardcoat penetrates the base metal for one-half of its thickness and builds above the original base metal dimension for one-half of its thickness. Thus, for a thickness of 50 )xm (2 mils) per side, the dimensional change of the workpiece would be 25 jxm (1 mil) per side. Commercially available coating thickness tolerances are the greater of 5 xm or 10% 

Advantages and Uses. Hardcoat anodize, because of its variety of desirable properties, has found widespread use in manufactured products. First, because of it extreme hardness, it is used in situations in which wear resistance is required. Applications include valve/piston assemblies, drive belt pulleys, tool holders and fixtures, and many other items requiring wear resistance. 

Second, because of its excellent resistance to corrosion, hardcoat is used on aluminum components in harsh environments. These include outside exposure in salt air, marine components, automobile wash equipment, components for the aircraft and aerospace industries, and food preparation machines. 

because hardcoat is an excellent electrical resistor, it can be used to insulate heat sinks for direct mounting of electrical or electronic equipment. Also, it is used in welding fixtures where some areas may need to be insulated from work. 

Fourth, because hardcoat is a naturally porous substance, it is used in many areas in which the bonding or impregnation of other materials to aluminum is needed. This coating bonds very well with paints and adhesives. Also, it can be impregnated with teflon (polytetrafluoroethylene, or PTFE) and many dry film lubricants to impart lubricating properties to the coating. 

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Relative Costs. Chromic anodize costs more than H2SO4 but less than hardcoat anodize. 

Relative Costs. Hardcoat anodize is the most expensive type of anodize. It is generally twice the cost of H2SO4 anodize and 50% more than C1O3 anodize. 

Hardcoat anodizing. As the name implies, a hardcoat finish is tough and durable and is used where abrasion and corrosion resistance, as well as surface hardness, are critical factors. Essentially, hardcoating is a sulfuric acid anodizing process, with the electrolyte concentration, temperature, and electric current parameters altered to... 

Suitable Alloys. Although almost all alloys can be coated, the 6000-series aluminum alloys produce the best bardcoat properties. As with the other anodize types, high-silicon die castings produce the lowest-quality coatings. Also, because the hardcoat process is sensitive to copper, alloys in the 2000 series should be avoided if possible. Alloys containing copper can be bardcoated, but only a relatively few commercial sources have the ability to coat these alloys with reliability. 

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