TY - CONF A1 - Müller, Thoralf A1 - Heyn, Andreas A1 - Fenker, M. A1 - Balzer, Martin T1 - Investigation on defect morphology and corrosion behaviour of TiMgN hard coatings on steel substrate T2 - EUROCORR 2014 - European corrosion congress N2 - Nitride hard coatings, such as Titanium nitride and chromium nitride coatings are widely used for applications focussing on wear protection and decorative purposes. Also these coatings are often applied on low alloyed steel substrates. The inevitable contact of the coated components with the environment through pores and coating defects bears the danger of corrosion of the steel substrate followed by further delamination of the coating and a loss of function of the component. A new attempt to increase the corrosion behaviour of those physically deposited hard coating systems is the implementation of magnesium. The positive effect of magnesium could be verified already electrochemically. Performed experiments on TiMgN have shown that corrosion resistance could drastically improved with increasing Mg content of the TiMgN up to 30 at% compared to steel substrates with applied titanium nitride hard coatings. Besides the clarification of the electrochemical and phenomenological effect of the magnesium on the corrosion behaviour, an additional aim of this work is the investigation of the coating defects, defect morphologies and their influence on the local corrosion behaviour. For this the incorporation of the magnesium and its effects on the coating material, the influence of coating growth related defects and the effect of the coating structure on the corrosion behaviour should be experimental examined by using innovative surface and material analysis methods such as FIB and TEM. Furthermore the evolution of the coating defects should be investigated by combing confocal microscopy with a new developed exposure test method using the electrochemical indication test KorroPad. The function of the KorroPad test, which was developed and patented [1] at the BAM for the detection of corrosion sensitive steel surfaces by indicating dissolution of iron ions [1], allows the detection and identification of critical coating defects for further microscopic investigation. Additional to that the KorroPad test simulates an accelerated exposure test by simultaneous absence of the disadvantages of typical short time exposure test like salt spray tests. Thus it allows a monitoring and analysis of the evolution of the critical coating defects and their influence on the local corrosion behaviour and the overall corrosion mechanisms. The results of this work should contribute to the development of new hard coatings with improved corrosion protection properties and also to a better understanding of the corrosion mechanisms of coated steel substrates. T2 - EUROCORR 2014 - European corrosion congress CY - Pisa, Italy DA - 08.09.2014 KW - Metallic coatings KW - Cathodic protection KW - Corrosion PY - 2014 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/31482 AN - OPUS4-31482 SN - 978-3-89746-159-8 SP - O EP - 7473, 384 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany