Cadmium Substitution - garteur

GARTEUR LIMITED
Abstract
A series of commercially produced aluminium and zinc based coatings have been
evaluated as potential replacements for cadmium plating for use on aerospace
components and fasteners manufactured from steel. Coatings examined included
electrodeposited zinc-nickel and zinc-cobalt iron, aluminium coatings produced by ion
vapour deposition and electrodeposition from an organic bath and metallic-ceramic
coatings containing zinc and aluminium flakes. An experimental aluminium - magnesium
coating produced by unbalanced magnetron sputtering was also included in the
programme. Tests have been conducted to establish the corrosion resistance and
tribological properties of the coatings and to compare their resistance to aircraft fluids
with cadmium plating. Studies have been made of the effects of the coatings on fatigue
performance and stress corrosion cracking resistance of a high strength steel. Other
coating properties examined include paint adhesion, electrical conductivity and galvanic
compatibility with aerospace aluminium alloys. The general conclusions are that none of
the coatings examined match the overall performance of cadmium plating. Estimates of
the relative costs of the coatings have been made. An environmental survey has also
been undertaken to compare the potential risks to workers involved in the manufacture
and maintenance of aircraft and to assess their impact on the environment. Areas for
future research are identified.
GARTEUR SM/AG17 TP128
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