Timothy Hall

Pulse Reverse Plating of Zn-Ni on Aluminum and Steel

This paper will discuss the development of an electrodeposition process to coat aluminum and steel with low hydrogen embrittlement (LHE) alkaline Zn-Ni. Zn-Ni is a potential replacement to the cadmium corrosion resistant coatings in aerospace, and fastener industries. Cadmium and its salts were part of the Annex XVII REACH list as well as Executive Order 13431. Cd is a known carcinogen and is deposited from a cyanide plating bath, these environmental and exposure concerns mandate the need for alternatives to Cd coatings. Specifically, LHE alkaline Zn-Ni has been shown to be a promising replacement due to its conductivity, corrosion resistance, and low embrittlement properties. In the given program we optimized the deposition and surface pretreatment conditions for an adherent LHE Zn-Ni alloy coating on aluminum and steel connector surfaces. The analysis examines the coatings performance with respect to adhesion, corrosion resistance, and embrittlement resistance when using both direct current and pulse control plating options.