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.
Aluminium was first isolated by Hans Christian Oersted in 1825 who reacted aluminium chloride (AlCl 3) with potassium amalgam (an alloy of potassium and mercury). Heating the resulting aluminium amalgam under reduced pressure caused the mercury to boil away leaving an impure sample of aluminium metal.