43056

Measuring the hardness of the anodized layer  

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We would like to know how the hardness of the anodized layer can be measured and how this hardness can be increased.
Thank you in advance and we look forward to your helpful advice.
Best regards,

Pooya
- Iran

Please provide the anodizing parameters you are employing, Pooya, and someone may be able to instruct you on what to adjust to increase the hardness.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

A microhardness tester with the appropriate load would probably give you a hardness reading that can be only somewhat be referenced to the more common rockwell hardness.
You increase hardness of a conventional sulfuric acid anodize by lowering the temperature (requires excellent agitation) and raising the voltage. Consider it as moving towards hard anodizing.

James Watts
- Navarre, Florida

The hardness of anodic film can be evaluated by the procedure given in "qualanod spesifikasyonlari". The procedure consists of rubbing a specified glass emery paper on to the anodised aluminium surface. The hardness of anodic film is poor if the anodising temperatute and sulphuric acid concentration is over 21 degC and 230 g/l respectively. The anodised aluminium must be taken out immediately from the anodising bath and good rinsing with higher PH must be applied not to softenn the anodic film by acidic solutions. And a proper sealing is a must.

Timur Ulucak
aluminum extrusions & finishing - Istanbul, Turkey

"And proper sealing is a must" (quoting the responder above me)


Sealing decreases the hardness of the anodic coating.

Marc Green anodizer - Boise, Idaho