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.
What is Chemical Passivation?Chemical passivation is a two step process. The ï¬rst step is to remove any free iron or iron compound that is on the surface, otherwise this iron will create a localized site where corrosion can continue. Acid is used to dissolve away the iron and its compounds.