What is Hard Anodizing?

Hard Anodizing or Hardcoat is an electrochemically produced grey layer of hard aluminum oxide on the surface of aluminum components. The coating grows integrally with the base metal and is corrosion and wear resistant and machinable. The thickness can be very closely controlled and be applied to a wide range of parts to suit applications from many industries.

How is it Produced?

Hard Anodizing is produced by specialist finishing companies, many of whom are members of the IHAA. The film is built up by a process of anodic oxidation in a cooled acid electrolyte thus preventing any thermal or physical distortion of precision engineered components. Secondary treatment such as impregnation with solid film lubricants and colored dyes are available.

Coating Properties

These are dependent upon alloy type and the process specification will typically give details of:

  • Thickness
  • Corrosion Resistance
  • Hardness and Wear Resistance
  • Electrical Resistance
  • Temperature Resistance
  • Friction Coefficient after lubrication

Coating Quality

Hard Anodizing is a well-established process suitable for meeting today's demanding quality requirements. National and International standards provide a basis for the specification, production, and testing of the coating. To ensure a satisfactory product it is important that the customer works closely with the Anodized at the specification stage on:

  • The application for the component
  • The aluminum alloy to be used
  • Corrosion and hardness requirements
  • Thickness range of the film final dimensional tolerances
  • The optimum location for contact points
  • Any approval requirements

All members of the IHAA have chemical and physical testing facilities that will ensure compliance with MIL, ISO, and numerous other standards.

Product Applications

Hard Anodizing finishes have an established reputation in a wide variety of applications. Major user industry sectors include:

  • Aerospace
  • Defense
  • Pneumatic
  • Hydraulic
  • Automotive
  • Energy
  • Chemical
  • Medical
  • Bakeware
  • Textile
  • Marine
  • Electronic