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 process to build up a layer of Chromium oxide armour on Austenetic Stainless steel of ships cargo tanks. This mono-molecular oxide layer is about 10 angstroms (one divided by 10 million-- millimeters) is invisible, chemically unreactive, self repairing and uni-potentialises the Stainless steel surface.