| 1 MINUTE READ

Type IIB Anodize

Question: I am looking for specific information regarding Type IIB anodizing per MIL-A-8625.
#plating

Share

Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

Question:

I am looking for specific information regarding Type IIB anodizing per MIL-A-8625. I’ve read that it is a low coating weight, non-chrome replacement for Type I (chromic acid) anodizing. What is the recommended bath chemistry, current density and temperature? Is this process obtainable from a standard sulfuric acid bath? R.A.

Answer:

Type IIB anodic coatings are produced in the standard Type II sulfuric acid bath and under virtually the same processing conditions as Type II. It is simply a thinner anodic coating that provides better corrosion resistance than Chem Film (Chromate Conversion Coatings), is a non-chrome finish and provides a very adequate base for organic coatings (painted finishes). When used as a paint base all rinsing after anodizing, as well as the sealing of the parts, must be done in surfactant-free solutions. Surfactants are wetting agents and if they are contained in the sealing chemistry will not provide as good a paint base as that provided by sealing in a surfactant-free sealing bath. Deionized water rinsing should be used before and after sealing. Sometimes Type IIB anodizing is specified where fatigue strength is important. The thinner coatings specified by this process give the base aluminum greater fatigue resistance than thicker anodic coatings on the same substrate.

I would suggest anodizing conditions of 70°F, approximately 12 asf. Bath concentration would typically be in the range of 165 g/liter to 275 g/liter (15% to 25% H2SO4 by weight). Coating thickness could range from 1 to 10 microns (0.00004 to 0.00025 inch). Boric-sulfuric falls in the category of Type IC.

 

Related Topics

RELATED CONTENT

  • Aluminum Surface Finishing Corrosion Causes and Troubleshooting

    In this paper, a review of several process solutions, examining coolants, solvent cleaning, alkaline clean/etch and deoxidizing/desmutting, listing intended and unintended chemical reactions along with possible mechanisms that would favor corrosion formation.

  • 2020 Vision: The Future of Coatings

    The year 2020 will be here before you know it, signaling the beginning of a new decade and bringing changes to the world as we know it.

  • Plating Process Control

    The cornerstone of quality and productivity for any finishing operation, process control is a plater’s key to success. To find out how far techniques have come, where they’re headed in the future, and how platers can raise the bar, Products Finishing convened a panel of experts for a roundtable discussion on the topic. With well over 100 years of combined plating experience, experts Greg Arneson, Art Kushner, Peter Gallerani and Joelie Zak share their thoughts.