Components located in the underbody of a vehicle are subjected to some of the harshest conditions created by a vehicle. The coating chosen for these parts will have a direct bearing on their longevity.
Underbody Exposure Is Unusually Harsh
In particular, the brake callipers, subframe mounting points and suspension parts, under the car, are exposed to the road, being subjected to stone chipping, salted road solutions and also the possibility of standing water.
Why the Alloy Outperforms Plain Zinc
Zinc Nickel Plating is typically 12% to 15% nickel, which is designed to produce a tighter alloy grain structure, which in turn slows the corrosion process. In high-chloride situations, plain zinc corrodes rapidly. Within the automotive engineering corrosion test to determine corrosion resistance by salt-spray exposure, the alloy composition of Zinc Nickel Plating can outlast plain zinc by a significant amount.
No Hydrogen Embrittlement Risk
Zinc nickel coating processes are known not to cause hydrogen embrittlement in steel fasteners and brackets. By using a lower acid concentration in the plating bath and a controlled baking of the coated part after plating, the risk of hydrogen absorption by the steel is kept within safe limits.
Performance Through Temperature Cycles
The coating adheres well to the base material and withstands changes in temperature and hence does not have cracking and subsequent corrosion risk due to moisture entry into micro cracks.
Dimensional Consistency on Precision Parts
This film is easily controllable and uniform, to meet the strict dimensional requirements for part finish of precision components such as brake calliper housings, etc.
More on Zinc Nickel Plating can be found at www.swmf.co.uk/surface-coatings/zinc-nickel-alloy-plating.
This corrosion protection is worthy of consideration when specifying parts for the automotive industry, compared to simple zinc coatings.