CORROSION OF ZIRCONIUM BORIDE AND ZIRCONIUM BORON-NITRIDE COATED STEELS

The corrosion behaviour of sputtered zirconium boride and zirconium bo ron nitride coatings on carbon steel substrates was investigated. Coat ings were produced employing non-reactive as well as reactive d.c. mag netron sputtering deposition using zirconium diboride targets. The cop per decoration technique was used to make visible the types of coating defects and their distribution. To quantify the corrosion behaviour, potentiodynamic polarization measurements and electrochemical impedanc e spectroscopy were employed. It was found that the corrosion protecti on depends strongly on the porosity and adherence of the coatings. Zir conium boron nitride films are more promising in this aspect owing to their lower number of coating defects.