Place the oject inside a vacuum chamber. If this doesn't work for your application, you should provide more details so that someone can answer your question.
This question is quite vague. It would be helpful if you could provide more information on the environment to which the component will be exposed. Items to include:
1. Temperature-- minimum and maximum?
2. Presence of humidity or water? What is the pH?
3. Presence of chemicals? Sodium chloride? Acids? Bases?
4. Is the component dynamically loaded? Is it subjected to impact, wear, or steady-state loading?
5. Is it necessary for the component to still be electrically conductive?
6. Will the aluminum component be in contact with another metal?
Coatings for aluminum castings are generally either polymer paints (epoxy, polyurethane, polyester, etc.) or anodic deposition coatings (aluminum oxide that may or may not be subsequently sealed). Maximum corrosion protection is usually obtained by anodizing the surface, sealing this anodized layer, and then applying relatively thick powder coatings as the final barrier layer. However, impact, fatigue, and wear are all factors that may favor another solution.
Sorry for the lack of information!!
The part which I need protection for corrosion is a aluminum sand cast A356 T6, it is assembled externaly on a equipment that stays outdoor, it suffers of corrosion and after some time of exposure the part looks very bad!
It happens specially on equipments which are mounted on the coast. The coast area in Brazil is a very corrosive enviroment, hot, windy, and salty. I knew about anodic protection and i would like to know more options to protect the part.
what would be the best paint to use?
Aluminum 356 - T6, although basically a Mg-Si alloy, may contain up to 0.25% copper. If copper is present, anodizing or aluminum oxides coatings will not work. This is because the copper is etched during the anodizing process, leaving an extremely porous structure.
Cladding the component in pure aluminum is also another option for preventing corrosion.
AlanD
Could you , please, get me more information about this process?
How do I proceed?
The component after sand cast and heat treated is also machined, I would need to clad this part after the machining! Would it affect the dimensional of the component?
Anodic protection won't really work on aluminum-alloys.You would need a metal which is electrochemically less noble than aluminium. Maybe you could achieve this by using a power supply. Does anybody know more about this ?
Is the aluminium part directly connected to another metal part or is it isolated ? In a humid environemnt, one could consider galvanic corrosion as a possibility.
Maybe you should consider coating if possible. For a salty exterior environment I suggest a vinyl, coal-tar epoxy or epoxy coating. Edwin Muller
KEMA Power Generation & Sustainables
Arnhem, The Netherlands
E-mail e.f.muller@kema.nl
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