Consumable magnesium anode for water heaters - with magnesium extruded over iron-tin coated iron core

摘要

A consumable magnesium anode for water heaters has an iron core which first receives a coating of tin 0.005-0.0076 mm thick which is then heated in a non-oxidising atmos. to a temp. (218 degrees C) for a time (2-8 hrs) adequate to turn the film of tin into a tin-iron alloy with a melting pt. of over 427 degrees C (538 degrees C). The magnesium sheath is finally extruded over this composite wire. This effectively prevents any galvanic corrosion between magnesium and iron. Tin is more compatible with Mg than aluminium. It does not react with the metal of the extrusion nozzle to form stress-induced cracks.