The potentiodynamic screening of materials for high efficiency gas-fired appliances

Abstract

As part of an overall programme to select materials for secondary heat exchangers in gas-fired condensing appliances, the corrosion characteristics of a number of commercially available austenitic stainless steels, and wrought and cast aluminium alloys were determined with a potentiostat. Results indicated that austenitic stainless steels performed generally better than the wrought or cast aluminium alloys evaluated. Wrought aluminium alloys showed better corrosion resistance than the various aluminium ‘LM’ casting alloys investigated. Of the stainless steels tested, type 316 showed the best overall characteristics. Amongst the wrought aluminium alloys assessed, AlMgSi showed the most corrosion resistance, closely followed by Al1SiMgMn and Al1Mn. Alloys Al7Si1Mg and Al12Si showed superior corrosion resistance to that of Al5Si3Cu.