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.
Pickling and Passivation are different forms of chemical metal finishing that provide protection on the surface of the metals. The process of doing pickling and passivation on a metal is not much of a difference. They both remove imperfections and rust on the surface of the metal.