Borate-free cleaners for lower toxicity
Cleaners containing borates have long been used to clean metal surfaces due to their mildly alkaline and de-greasing properties. Apart from controlling the pH of the cleaning solution, borates help to emulsify oils and are mildly abrasive. Since borate is now considered hazardous, the EU-funded ‘Borate free cleaners for aluminum alloys’ (BFCLEANER) project wanted to develop and test borate-free cleaners for the aluminium industry. Researchers compared four borate-free formulations (two developed by a participating company and two commercially available ones) with borate-containing cleaners. Their relative cleaning efficiencies and their corrosiveness were analysed on two aluminium alloys widely used in the aeronautics industry. BFCLEANER's borate-free agents removed grease and solid oils adsorbed to the metals with the same or higher efficiency as borate-containing cleaners currently on the market. Moreover, they performed with optimal efficiency at lower concentrations and at lower temperatures, thus saving energy. Removing borate from alkaline degreasing agents will be particularly useful for aluminium anodising plants, which must by law eliminate borate from their waste water. Anodising is a process in which aluminium is treated in order to create a protective layer of aluminium oxide to prevent corrosion and abrasion. The project's borate-free cleaners are therefore likely to find wide application in industries and products ranging from aeronautics to iPod cases.
Keywords
Borate, borate-free cleaners, aluminium, alloys, anodising