Silazane‐based zinc‐filled coating system for corrosion protection of steel in humid and salt water containing environments

Abstract In this study, a lamellar corrosion protection coating filled with zinc, zinc‒magnesium, and aluminum flakes using the polymer‐derived ceramic route is developed. The goal is to investigate the potential of polysilazanes as matrix material for zinc‐filled base coats providing enhanced temperature stability. Therefore, emphasis is placed on the investigation of the influence of the treatment temperature on the microstructure of the coating using scanning electron microscopy and X‐ray diffraction as well as on the mechanical properties using scratch tests. Additionally, the effect of different filler compositions on the protection properties is studied. The best corrosion protection in 5 wt.% sodium chloride solution is attained with a zinc content of 37.5 vol.%, a magnesium content of 30 vol.%, and an aluminum content of 12.5 vol.%. The coating system exhibits improved temperature stability up to 400°C. At higher temperatures the oxidation of the zinc and the zinc‒magnesium fillers leads to a severe reduction in corrosion protection. The scratch resistance is not affected by the thermal treatment.