Microstructure and corrosion properties of laser clads of magnesium base alloys for laser generated cylinder liners

Abstract

The aim of this investigation was the production of wear and corrosion resistant coatings on magnesium base alloys. In particular it was proposed to generate by laser layers which operate as cylinder liners in a magnesium engine block thus replacing the currently used cast iron cylinder liners used in aluminium engines. These layers were produced using a 10 kW CO 2 laser and powder mixtures of aluminium + copper, aluminium + silicon and an alloyed aluminium-silicon powder in the single step process. The properties of these layers were characterised by metallographic investigations such as optical and scanning electron microscope and hardness measurements. The corrosion resistance has been determined using a modified immersion test in sulphuric acid with drying cycles in air. These conditions are comparable to the conditions found in combustion engines where the layers are to be used. Positive results were obtained with respect to the microstructure formation. Intermetallic phases can ensure a good wear resistance in laser treated material. An acceptable corrosion resistance was achieved by laser alloying with AlSi30 powder.