This painless condition occurs when the little bumps on your tongue grow long and trap bacteria that live in your mouth -- making the tongue look black and hairy. Causes can include antibiotic use, poor oral hygiene, smoking, drinking a lot of tea or coffee, and not producing enough saliva.
Hello, Jie. The word passivate is a bit troublesome because aluminum cannot be passivated in the same sense as stainless steel; but it can be passivated in the same sense as zinc plating, i.e., with a chromate conversion coating.
Passivation is a chemical process that is used to help restore contaminated stainless steel to original corrosion specifications. Parts are placed in baskets and submersed into a diluted nitric acid or citric acid solution for a specified length of time and temperature.