PRODUCTION OF HEAVY PURE ALUMINIUM COATINGS ON SMALL DIAMETER TUBING

摘要

PRODUCTION OF HEAVY PURE ALUMINIUM COATING ON SMALL DIAMETER TUBING A method for producing heavy pure aluminium coatings on small diameter steel tubing having an average thickness of 100-200.mu.m, to provide outstanding resistance to corrosion, and to maintain integrity in the face of abrasive action, and with coating ductility and adherence sufficient to permit double flaring. The method is highly useful in the manufacture of Bundyweld tubing for automotive brake lines, and single wall tubing for refrigeration or air conditioner heat exchangers. Various surface preparations are disclosed; after surface preparation the tube is uniformly heated to a carefully regulated peak temperature in a non-oxidizing high intensity direct fired furnace, followed by passing the tube vertically upward through a shallow pool of molten aluminium, whereby to cast on a -thick coating, followed by "free exit" finishing, air quenching, and, if desired, redrawing.