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Causes of chromium cracks and operating conditions which minimize visible cracked hard chromium plating have been identified as a result of a literature study and published data study. Elimination of visible chicken wire cracking in chromium plating production has been obtained by reducing the chromic acid to sulfate ratio and current density in one case study. Analysis of data in the study indicates consistency in ways of reducing cracks. An experimental design consisting of chromic acid to sulfate ratio, current density and temperature is proposed to verify these findings.

A zinc-nickel (Zn-Ni) alloy electroplating process has been developed which provides equivalent or superior performance to cadmium (Cd) plating in the following areas: corrosion protection, low hydrogen embrittlement, lubricity, torque tension, installation force, and electrical conductivity. In addition, it offers reduced tendency for exfoliation corrosion of coupled or contacting aluminum structure as compared to Cd plating. Conventional electroplating tank facilities can be converted to the Zn-Ni process with minimal modification. The elimination of Cd and cyanide reduce the waste hazard significantly, and the excellent technical performance makes the low hydrogen embrittlement Zn-Ni electroplating process a viable alternative to Cd plating of high- and low-strength steels in aircraft and other applications. This paper is an update of progress for development and implementation of the process during 1983.

New environmental regulations all over the world encourage the use of alternatives to cadmium plating for corrosion-protection systems used on steels. Boeing patents are pending on a non-cyanide replacement zinc-nickel alloy electroplating process with superior properties, including low hydrogen embrittlement and good corrosion protection, for use on high-strength steels and other substrates. Another advantage of this process is low cost because conventional electroplating tank facilities can be used and waste treatment cost can be reduced. The feasibility of this zinc-nickel plating process has been successfully demonstrated in the laboratory and is scheduled for manufacturing scale-up during 1983.