Corrosion protection of automotive brake lines tubing using Zn-Al coatings deposited by magneto-hydrodynamic (MH) techniques

摘要

Brake lines are an important component of the overall vehicle safety system. Because brake lines carry brake fluid from the master cylinder to various other brake parts, it is important to keep them in good repair. Vehicles may be susceptible to brake pipe corrosion that can occur after seven to eight years of exposure to winter road salts. Published data by National Highway Transport Safety Administration (NHTSA) shows brake line corrosion problems are often linked to the coating materials. Vehicles driven in regions where road salt is employed for de-icing are more prone to corrosion-related issues. If brake line corrosion is not properly addressed, there is the potential of brake tube failure which could result in a crash. Metallic and organic coatings used on brake lines are designed to minimize corrosion, abrasive wear and, therefore, to be capable of use where the tubing is exposed to the aggressive elements, for example, on the underside of a vehicle chassis. The present paper discusses the developments introduced by CSA on the galvanizing of brake line tubes for improving their corrosion resistance. These improvements have been obtained by using a new type of deposition based on Magneto-Hydrodynamic deposition (MHD) of zinc alloy coatings. Effects of MHD on the liquid metal flow, end coating-microstructure and corrosion performance will be discussed.