Thread 140/78
Problem of soft anodic coatings
Soft anodizing
I am experiencing soft anodic coatings. They tend to scratch easily. I am anodizing with a current density of 1.5amps per square decimeter, with the anodizing time of around 40-45 minutes which should be giving me about a 25 micron layer. My bath temperature varies between 18-21 °C. This is for type II sulfuric anodize. I seal the anodic coating with straight de ionized water for about a hour. What am I doing wrong!
Steve Power- Nelson, New Zealand
publicly reply to Steve Power
Steve...you didn't mention the alloy you are working with, or the electrolyte composition.. both of which could be contributing to your problem. Is this a new problem for you.. are you an experienced anodizer? Do you regularly monitor your DI water for conductivity/resistivity, and pH? Is your Al content of your bath ok? There are alot of variables to check.
Marc Green
anodizer - Boise, Idaho
publicly reply to Marc Green
Your temperature is correct, your current is correct, but probably your acid concentration is too high. Get it down to 15 %/wt which is 12 fluid ounces per gal of 66 degree Baumé Sulfuric Acid which is 165.3 grams per liter.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
publicly reply to Robert H Probert
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