ZINC PHOSPHATE
The chemical formula of
zinc phosphate
is Zn3(PO4)2
1.Properties: Pure zinc phosphate is the best substitute of conventional antirust pigments containing heavy metals such as lead and chrome.
2.Usage: Pure
zinc
phosphate is widely used in various coating materials for preparation of waterproof, acid-resistant or corrosion preventive coating materials such as phenolic paint, epoxy paint, acrylic paint, paste paint and water-soluble resin paint in the fields of shipbuilding, automobile, industrial machinery, light metal, household appliances and metal containers for foods.
Among the phosphate pigments,
zinc phosphate found the widest application in paints,
since it provides excellent corrosion resistance and is non-toxic.
The most
commonly applied paint pretreatment for developing good
bonding qualities between paint and the galvanized or
galvannealed coatings on steel sheet is
zinc
phosphate. In addition to the excellent effect that a
zinc phosphate coating has on paint adhesion, it also aids to
decrease, often dramatically, the tendency for paint
disbondment during subsequent atmospheric exposure in a
corrosive environment.
Zinc phosphate
coatings can be applied to the galvanized sheet while it is in
coil form by either the steel manufacturer or a coil coater
(manufacturer of prepainted sheet), or it can be applied to
the cut sheet or fabricated article by the end-use
manufacturer. The usual
zinc phosphate
process involves several steps, both if the coating is applied
on a coil line or by the part manufacturer. If there are oils
present on the surface of the galvanized or galvannealed
steel, the first step is the removal of the oil by degreasing.
This might involve cleaning with the use of an aqueous,
alkaline cleaning solution or by other forms of degreasing
with the use of solvents. Preferably, if the phosphating is
done on a coilprocessing line, the next step involves the use
of a conditioning stage; the application of a titanium
phosphate conditioner to prepare the galvanized/galvannealed
surface for the development of a superior
zinc
phosphate coating. The titanium phosphate aids in the
development of a uniform phosphate coating with small
zinc
phosphate crystals by depositing sub-micron size
particles which act as seeds to promote the growth of zinc
phosphate crystals on the surface of the galvanized sheet.
Common Applications of Zinc Phosphate
Coatings:
?Oil & Gas Industry:
Primer for critical components
?Defense: CARC primer. Non
reflective finish for equipment.
?Automotive: Base for
organic coatings.
?Aerospace: Break-in of moving parts and
threads. Primer for specialized coatings.
?Gears &
Bearings: Holds lubricants on surface.
?Mining Equipment:
Primer for fluoropolymer coatings.
3.Zinc phosphate chemical examination report :
