THE METAL Finishing Association (MFA) has been granted funding from the UK's Department of Trade & Industry (DTI) to develop a technique for chromium-free passivation. In line with the requirements of the DTI's LINK programme, the research will be undertaken by Loughborough University of Technology with collaboration from chemicals' supply company Wm. Canning and a consortium of end-users and surface-engineering companies, headed by the MFA. The objective of the programme is a hexavalent-free solution with the same corrosion resistance as conventional chromate that can be applied without increasing operating costs. Passivation is a corrosion-protection system that effects a 'conversion' coating on metal surfaces, and it is widely specified as a cost-effective method of enhancing the performance of zinc and aluminium. However, inhalation of the chromate ions is recognized as potentially carcinogenic, leading to serious health and safety concerns about its use in the workplace. Unless properly handled, chromates can cause ulceration and environmental contamination. An effective replacement is therefore highly desirable in order to protect a major part of the zinc-plating industry. As yet, however, an effective and low-toxicity alternative for chromates is not a serious commercial reality.
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