Fluoride

Hydrogen fluoride is a chemical compound with the formula HF. It is the principal industrial source of fluorine, often in the aqueous form as hydrofluoric acid, and thus is the precursor to many important compounds including pharmaceuticals and polymers (e.g. Teflon). HF is widely used in the petrochemical industry and a component of many superacids

K2SiF6An odorless, white crystalline compound; slightly soluble in water; used in vitreous frits, synthetic mica, metallurgy, and ceramics. Also known as potassium silicofluoride.

Hexafluorosilicic acid is the chemical compound with the formula H2SiF6. Hexafluorosilicic acid refers to an equilibrium mixture with hexaflurorosilicate anion (SiF62−) in an aqueous solution or other solvents that contain strong proton donors[1] at low pH.

Chromate conversion coating is a type of conversion coating applied to passivate aluminium, zinc, cadmium, copper, silver, magnesium, tin and their alloys to slow corrosion.[1] The process uses various toxic chromium compounds which may include hexavalent chromium.