Quote:
Originally Posted by MPaulHolmes
wow! What is this type 3 anodizing?! How do I do it? Can I send in a block of aluminum to someone, and they anozide it?
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Unfortunately, as I understand it, it can't be done DIY very well. It takes a lot of current and requires a very carefully controlled temperature bath.
Otherwise, it's pretty well the same process used for the colorful anodizing often seem. It's just a lot tougher. Half the hardcoat anodizing actually sinks into the pores formed by the acid bath (typically 1/2mil deep) and half sits on the surface (typically 1/2mil thick). What's on the surface forms the "insulation" and is incredibly tough. Do not plan to do any machining or drilling of a hardcoat anodized piece of alumunum! It will eat up your bits.
But, a large number of anodizing facilities can do Type III hardcoat anodizing (the military uses it a lot). The only problem is that it comes in only one color, dark gray/black. They typically charge a lot fee for a basket full of parts. The more parts you send in at a time, the less expensive it will be for each part.
If you don't have a lot of parts (100+), it can get expensive. But, if you're pushing the thermal envelope for a design and can't have a "hot" heat sink or use mica or thermal pads between the MOSFETs and heat sink (because of their high thermal resistance), hardcoat anodizing is the way to go.