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Author: Subject: how to chemically waterproof sodium silicate coating
John paul III
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[*] posted on 20-12-2020 at 09:57
how to chemically waterproof sodium silicate coating


I plan on making a machine out of cast aluminium, and some moving parts i want to coat with a solution of sodium silicate (Na2O:3SiO2). After drying without boiling, it should make a layer of true glass, and solve the abrasion problem of bare aluminium.

But since in theory the coating could be redissolved by moisture,
Is there a way to treat the surface so it becomes insoluble? For example, if i put it in molten calcium nitrate, would the surface become insoluble soda lime glass?
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Boffis
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[*] posted on 20-12-2020 at 10:15


Sodium silicate solution is very alkaline and attacks aluminium. You will not get a glassy layer at room temperature but you will get an amorphous layer sodium aluminium silicate. If subjected to steam or atleast moderately elevated temperatures in the presence of water you may get a clay or zeolite like coating but I doubt it will be particularly abrasion resistant.
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rockyit98
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[*] posted on 20-12-2020 at 10:21


anodize Al first. maybe try one of that ceramic coating paint.



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Fulmen
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[*] posted on 20-12-2020 at 12:10


I agree. Your focus should be on anodizing. It's really not hard: A "dumb" 12V charger and 10-15% sulfuric acid. Make sure to keep the bath cool. Cook for 30 minutes and Bob's your uncle.



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