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Benefits and Uses
ZINC andZINC NICKEL PLATING
Why use zinc plating?• Provides a barrier layer against corrosion to bare steel•Zinc is a sacrificial coating and will corrode (white corrosion) before the steel begins to (red rust)
• Final product is cosmetically pleasing•Can be plated in either clear, yellow, black, olive drab, and many other dyed colors• Finish is uniform and very bright
Zinc Plating
Zinc Plating
• Application of zinc plating• Electrochemical process that applies a thin
layer of zinc metal to the bare steel surface• The plating can be either done in rack or
barrel• Thickness of the plating is usually
between .0002” and .0005”
Zinc Plating
• Application of zinc plating• A supplementary chromate coating can be
applied to provide additional corrosion protection• This provides the color to the plating and
can be either hexavalent or trivalent chrome or a chrome free passivate
• Sealants can used to increase resistance to white corrosion as well as modify and lower the coefficient of friction
Zinc Plating
Zinc Plating• Issues with zinc plating• Government Regulations• REACH and RoHS• Plating suppliers were required to provide
alternative finishes that did not use hexavalent chromium• Existing finishes that were compliant did not
provide the necessary corrosion protection• Great strides have been made to replace hex
chrome and now a trivalent chromate in both yellow and clear is the industry standard• ELV was one of the first such clear trivalent
chromates to be available and in use at Saporito
• Issues with zinc plating• Industry Standards• Increased corrosion protection requirements• 10 years ago the standard was 72 hours to
white corrosion and 240 hours to red rust when testing with a 5% neutral salt spray test
• Standard requirements have risen to over 120 hours to white corrosion and 360 hours to red• Again the plating suppliers are having to
find alternatives
Zinc Plating
• Introduced as an alternative to Cadmium Plating• Government regulations on cadmium led to need
in the industry for coatings that provide similar properties with environmentally safe products
Zinc Nickel Plating
• What is Zinc Nickel Plating• Same process as zinc plating but both zinc and
nickel are deposited on bare steel at the same time• Deposits range from 5% to 20% nickel with the
remainder zinc• Can be processed in both rack and barrel• Chromate coatings can be applied to increase
corrosion protection• Like zinc plating they are available in clear,
yellow, and black• Sealants are available to reduce the coefficient
of friction
Zinc Nickel Plating
Zinc Nickel Plating
• Advantages of Zinc Nickel Plating• Hardness• Typical hardness value of the as deposited
coating is 3 times higher than zinc plating
• Corrosion Protection• Far and away the superior coating in terms
of corrosion protection to both white and red corrosion• Can achieve a minimum of 750 hours to
white and 2000 hours to red rust
Zinc Nickel Plating
Corrosion Protection of Coatings
Red
White
• Advantages of Zinc Nickel Plating• Variety of Industries Serviced• Marine applications• Agriculture• High resistance to fertilizer • Automotive• Electronics• Corrosion products not as loose and
voluminous as with zinc plating
Zinc Nickel Plating
• Advantages of Zinc Nickel Plating• Throwing Power• Has excellent coverage in both low current
and high current areas• This provides a very uniform coating on
the most complex of shapes
Zinc Nickel Plating
• Drawback of Zinc Nickel Plating• Appearance• Very functional coating but a difference in
cosmetics from zinc plating• Due to addition of nickel in the deposit the
clear coating has a lot of iridescent to it• However the black chromate is uniform
and is superior to zinc trivalent black chromates
Zinc Nickel Plating
Zinc Nickel Plating
• Drawback of Zinc Nickel Plating• Yellow Chromate• At this time the yellow chromate is only
supplied in the hexavalent form• Only clear and black would be both REACH
and RoHS compliant
Zinc Nickel Plating
• Zinc plating has been around for a long time and provides a very good coating for most industries
• Government regulations and industry corrosion requirements have outpaced existing zinc technologies
• Zinc Nickel has been introduced as a suitable replacement for Zinc plating
• Zinc Nickel provides maximum hardness and corrosion protection that is well beyond industry requirements
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