John paul III - 20-12-2020 at 09:57
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?
Boffis - 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.
rockyit98 - 20-12-2020 at 10:21
anodize Al first. maybe try one of that ceramic coating paint.
Fulmen - 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.