Impreglon Australia offers three types of zinc coatings to our customers.
This is the long established and very common finish that is seen on many products generally intended for internal use. It can be either silver or the now less common yellow chromate seal.
The coating process involves cleaning to remove all surface contaminants, followed by the electroplating process where the part is immersed in a vat of specially formulated zinc chemistry. A DC current then deposits the zinc onto the work. The electroplating process will deposit thicker coatings on the outside edges and a lesser thickness in the recesses. In deep recesses, there may be no coating at all, which can become a source of corrosion.
Most zinc electroplated coatings have an added post plating conversion coating treatment, which will further enhance the corrosion resistance.
These coatings have been sold under a number of trade names for many years, but have recently become more readily available. The coatings have very good corrosion resistance and are now used for many industrial applications.
The coatings are liquid and they contain zinc and aluminium powders which take the form of very small flakes which overlap to form a highly efficient galvanic coating. Commonly treated parts range from small nuts and bolts processed in bulk to larger parts that are sprayed with conventional or electrostatic spray guns. Many of these coatings can be top coated with special sealers to further enhance the corrosion resistance. These top coats can be coloured if required and can also incorporate additives to decrease torsion in threaded applications.
Zinc flake coatings fit into service conditions between zinc electroplating and galvanizing.
As with most finishing applications, surface preparation is critical for a satisfactory performance. This can take the form of either abrasive or chemical conversion coatings.
Being a liquid coating, there can be some filling of small holes, screw heads etc. which may present a problem on some parts.
These are chemical coatings applied either by dipping or spraying and are generally applied to a clean steel surface. The coatings on their own have limited corrosion resistance and are generally post-treated with oils or other sealants. Most commonly, these coatings are used for subsequent painting or finishing with other organic coatings.
All of these coatings make excellent undercoats for powder, e-coat or paint to give greatly increased corrosion resistance.