Due to the improved corrosion resistance of magnesium alloys brought forward by the development of the high purity grades 20 years ago, the use of die cast magnesium components has moved towards more and more demanding applications. The corrosion resistance is sufficient so that magnesium is used in the underbody environment of vehicles without additional general corrosion protection, although special attention must be given to galvanic corrosion protection. There has recently been an increasing interest in both semi-exterior and exterior automotive parts. Since magnesium alloys are not compatible with standard automotive phosphate treatments, the parts need to be pre-coated prior to assembly. For such components, the challenges are to find efficient, environmentally friendly pre-treatments and robust coating systems that can maintain their integrity through the assembly process. The present paper reviews some of the established and newly developed methods for corrosion protection and finishing of die cast magnesium automotive parts.
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