Hoch, M., Kaczmarek, M., and Ahr, M., "Faster, Better, Economic - Newest Acid Zinc-Nickel Technology for Brake Caliper Plating," SAE Technical Paper 2017-01-2507, 2017.
The demand for zinc-nickel coatings continuously increases in the automotive industry due to their high corrosion protection as well as superior wear and heat resistance compared to pure zinc platings. The state-of-the-art plating systems in the brake caliper industry are acid zinc-nickel electrolytes, as only they allow for direct plating on cast iron.Cast iron is the most common base material for the production of automotive brake components due to excellent mechanical and thermal properties. Well suited coatings will preserve the functional properties and provide additional advantages like improved corrosion protection and homogeneous and long lasting appearance.Consistently increasing quality demands, extended warranty periods and cost pressure lead to further developments and force the industry to look for new solutions. Therefore improvement of throwing power (thickness distribution) of acid zinc-nickel electrolytes would allow for a reduction in plating time and thus an increase in productivity.More homogeneous coatings on the other hand will lead to an improvement of corrosion resistance and quality. With an appropriate post-treatment consisting of passivate and reactive inorganic sealer, a high-end system with superior cathodic corrosion protection, highest wear resistance and perfect appearance is achieved.This study will introduce Atotech´s new ammonium and boric acid-free acid zinc-nickel electrolyte - Zinni® 220 - which, as a result of the significantly improved throwing power, sets new standards in acid zinc-nickel plating. It opens enormous possibilities to improve quality and productivity while keeping the highest corrosion protection and perfect appearance. The superior thickness distribution and nickel incorporation will be presented and compared to conventional acid zinc-nickel electrolytes. Overall this results in higher plating quality at reduced cost and improved productivity.