Generation of protective ceramic coatings on magnesium by laser treatment of Al2O3/ZrO2 filled organosilazane.

Protective ceramic coatings are frequently the most common solutions for problems like corrosion and wear. Polymer derived ceramics technology is suitable for the preparation of ceramic coatings by pyrolysis in a furnace but requires high temperatures for the ceramization. To overcome this restriction a Nd:YVO 4 laser (λ = 1064 nm) as energy source was used to process a novel ceramic coating system composed of an organosilazane with zirconia and alumina particles specially to protect magnesium. The resulting dense ceramic coating with a thickness up to 20 µm exhibits very good adhesion (25.9 ± 2.7 MPa) to the magnesium substrate, exceptionally high hardness (19.79 ± 1.90 GPa), an outstanding thermal shock stability but also a low coefficient of friction (0.21 ± 0.02) and a very good wear protection towards a SiC counter body. Furthermore, the coating protects the magnesium substrate effectively against corrosion (5 wt% aqueous NaCl solution). [ABSTRACT FROM AUTHOR]