Cadmium Substitution - garteur

GARTEUR LIMITED
5 Environmental survey
Surveys were made to establish the effect of the coatings being evaluated on workers
involved in the manufacture and maintenance of aerospace components and the impact
of the coatings on the environment.
5.1 Effect on workers
The survey considered the potential risk to workers from the handling of aerospace
coated parts during the assembly and maintenance of aircraft. It also examined the risks
to workers in metal finishing shops with regard to the application of the coatings. Tables
13 and 14 summarise the findings of the survey.
5.2 Effect on outside environment
A survey of each of the coatings was made to establish the effects of the coatings on the
environmental. Four aspects were considered:-
• costs of disposal of waste materials
• remnants of corroded coatings
• waste water flow
• air pollution
Results of the survey are summarised in tables 15 to 18.
Table 15 indicates that the cost of disposing of waste materials produced by the
alternative coating processes are likely to be much lower than that incurred with
cadmium electroplating. In the case of the two physical vapour deposition processes,
IVD aluminium and UBMS aluminium - magnesium, accurate costs are not available.
Several of the processes involve the use of post plating passivation treatments
containing chromates and there will be some costs concerned with the treatment of rinse
waters etc.
One problem encountered with cadmium plated parts is the handling of components
which are corroded. Cadmium corrosion products are highly toxic and may be taken into
the body if suitable health and safety precautions are not taken. The assessment given
in table 16 suggests that the health risk from corrosion products on the alternative
coatings is minimal.
Potential problems associated with the treatment and disposal of waste water from the
various coating processes are summarised in table 17. The main conclusion is that the
alternatives do not present major problems. Waste water from cadmium electroplating
facilities requires considerable treatment to reduce the cadmium ion concentration to a
level that meets environmental controls. Some problems may be encountered with the
other coatings, which employ chromate based passivation treatments to improve
corrosion resistance and paint adhesion. This includes the electrodeposited zinc alloy
coatings and the PVD and electrodeposited aluminium coatings. Rinse solutions
containing hexavalent chromium ions will need to be treated before they may be
discharged into rivers etc.
The possible air pollution risks arising from chemicals employed in the various coating
processes are outlined in table 5.6. Some slight hazards result from the use of butanol in
the production of Magni-coat and the use of toluene in the aluminium electrodeposition
process. The risk from cadmium compounds used in plating are well documented if
allowed to become airborne.
GARTEUR SM/AG17 TP128 Page 15