TY - JOUR A1 - Balzer, M. A1 - Fenker, M. A1 - Kappl, H. A1 - Müller, Thoralf A1 - Heyn, A. A1 - Heiss, A. A1 - Richter, A. T1 - Corrosion protection of steel substrates by magnetron sputtered TiMgN hard coatings: Structure, mechanical properties and growth defect related salt spray test results N2 - Hard and wear resistant coatings deposited by PVD techniques have been characterized for decades for their capabilities to protect steel substrates from corrosion. In the present work the effect of Mg incorporated into TiN coatings is described in terms of the corrosion behavior as well as the mechanical and structural properties. TiN and TiMgN films with Mg contents between 10 and 35 at.% were deposited onto mirror polished 100Cr6 (1.3505) steel samples with 2.5 and 5 μm thickness by using DC magnetron sputtering. The corrosion protection capabilities of the coatings were characterized by neutral salt spray (NSS) test, considering the amounts and sizes of growth defects inherent in each coated sample as determined by a recently developed optical scan method (Large Area High Resolution mapping). The defect data were statistically analyzed for improved interpretation of NSS test results. Chosen growth defects were additionally analyzed by focused ion beam technique. Furthermore the coating composition and morphology, the hardness and the tribological behavior were characterized. Polished steel samples coated with 2.5 μm TiMgN containing about 35 at.% Mg were in the plane free of corrosion after 24 h in a NSS test. TiMgN with 10 or 20 at.% Mg only provided a slightly improved corrosion protection in relation to pure TiN coatings, which was limited to certain types of growth defects. The highest Mg containing coatings exhibited a decreased hardness down to 1200 or 1800 HV depending on type of deposition (HV 1200: Ti- and Mg-target with rotating substrate holder, 1800: Mg-plugged Ti-target with static substrate holder), but also showed a strongly improved wear resistance against Al2O3 related to pure TiN. By analyzing the NSS test results it was found that the corrosion behavior of the coated samples did not only depend strongly on the Mg content, but also on the sample individual defect concentrations. Therefore this subject is extensively discussed. KW - Physical vapour deposition (PVD) KW - Corrosion KW - Growth defects KW - Pinholes KW - Magnesium KW - TiMgN PY - 2018 DO - https://doi.org/10.1016/j.surfcoat.2018.05.037 SN - 0257-8972 VL - 349 IS - 9 SP - 82 EP - 92 PB - Elsevier B.V. AN - OPUS4-45712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heyn, A. A1 - Müller, Thoralf A1 - Balzer, M. A1 - Fenker, M. A1 - Kappl, H. T1 - Corrosion protection mechanisms of TiMgN hard coatings on steel N2 - . Hard coated steel components are used in a wide application range, mostly for protective, wear resistant and decorative purposes. Despite of these coatings being regarded as relatively dense, there is always a high risk of localized corrosion when a coated low alloyed steel component encounters a surrounding high humidity atmosphere or even an aqueous medium. An approach to enhance the corrosion properties is the addition of magnesium to physical vapor deposited hard coatings, like TiN. It has been found that there is a remarkable increase in corrosion resistance in dependence of magnesium content of the TiMgN coating and its surface properties. In this work the authors will explain the underlying corrosion protection mechanisms by means of electrochemical and analytical studies. The positive impact of magnesium in the coating relates on its preferred dissolution vs. steel. This causes the potential to shift to more negative direction with respect to the steel substrate and additionally leads to a temporarily passivation of the steel due to alkalization of the surrounding electrolyte by formation of magnesium hydroxide. T2 - 20. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 14.03.2018 KW - Corrosion KW - Titanium nitride KW - PVD hard coating KW - Magnesium PY - 2018 SN - 978-3-00-058901-0 SN - 1439-1597 VL - 72 SP - 74 EP - 83 PB - Eigenverlag CY - Chemnitz AN - OPUS4-44526 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heyn, A. A1 - Müller, Thoralf A1 - Balzer, M. A1 - Fenker, M. A1 - Kappl, H. T1 - Corrosion protection mechanisms of TiMgN hard coatings on steel N2 - Hard coated steel components are used in a wide application range, mostly for protective, wear resistant and decorative purposes. Despite of these coatings being regarded as relatively dense, there is always a high risk of localized corrosion when a coated low alloyed steel component encounters a surrounding high humidity atmosphere or even an aqueous medium. An approach to enhance the corrosion properties is the addition of magnesium to physical vapor deposited hard coatings, like TiN. It has been found that there is a remarkable increase in corrosion resistance in dependence of magnesium content of the TiMgN coating and its surface properties. In this work the authors will explain the underlying corrosion protection mechanisms by means of electrochemical and analytical studies. The positive impact of magnesium in the coating relates on its preferred dissolution vs. steel. This causes the potential to shift to more negative direction with respect to the steel substrate and additionally leads to a temporarily passivation of the steel due to alkalization of the surrounding electrolyte by formation of magnesium hydroxide. T2 - 20. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 14.03.2018 KW - Corrosion KW - Titanium nitride KW - PVD hard coating KW - magnesium PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-457117 DO - https://doi.org/10.1088/1757-899X/373/1/012009 SN - 1757-8981 VL - 373 IS - 1 SP - 012009, 1 EP - 10 PB - IOP Publishing Ltd AN - OPUS4-45711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Thoralf A1 - Heyn, Andreas A1 - Balzer, Martin A1 - Fenker, M. T1 - Untersuchungen zum Einfluss von Magnesium auf das Korrosionsverhalten von TiMgN - Hartstoffbeschichtungen auf Stahlsubstraten N2 - Hartstoffbeschichtungen werden heutzutage in vielen praktischen Bereichen zur Verbesserung der Verschleißbeständigkeit und aus dekorativen Gründen auf verschiedenste Stahlbauteile aufgebracht. Beim unvermeidlichen Kontakt mit einem umgebenden wässrigen Medium über Schichtporen und-fehler sind die beschichteten metallischen Substratwerkstoffe jedoch der Gefahr lokaler Korrosion ausgesetzt, was mittel-oder langfristig zum Funktionsverlust der Bauteile führen kann. Ein neuartiger Ansatz zur Veränderung der mechanisch-technologischen, optischen sowie elektrochemischen Eigenschaften hartstoffbeschichteter Bauteile ist der Einbau des Elements Magnesium in den physikalisch abgeschiedenen Überzug (z.B. TiN). Untersuchungen von Fenker et al., die die Charakterisierung dieser neuartigen TiMgN-Überzüge zum Ziel hatten, konnten zeigen, dass sich mit zunehmenden Mg-Gehalt die Farbe des Überzugs von dem typischen goldgelb des TiN über violett, blau bis hin zu metallisch grau verändert und weiterhin die Oxidationsbeständigkeit deutlich gesteigert wird. Weiterhin zeigte sich in 24-stündigen neutralen Salzsprühtest, dass sich die Korrosionsbeständigkeit der mit TiMgN beschichteten Stähle mit steigendem Mg-Gehalt deutlich verbessern und die Korrosion des Stahlsubstrats zeitlich verzögert wird. Ausgehend von diesen phänomenologischen Beobachtungen wurden drei verschiedene Arbeitshypothesen über die elektrochemische Wirkungsweise des Magnesiums im TiMgN-Schichtsystem entwickelt, die ursächlich für die verbesserte Korrosionsbeständigkeit seien können. Die drei Arbeitshypothesen sind: · Potentialanpassung: Das Mg verringert das Freie Korrosionspotential der Schicht, welches sich dem des Stahlsubstrates annähert, womit Lochkorrosion verhindert bzw. verzögert wird. · Galvanische Anode/Opferanode: Das elektrochemisch unedlere Mg in dem Schichtsystem geht bei Vorhandensein von freiliegendem Fe bevorzugt in Lösung und schützt so den Stahl als galvanische Anode. · Versiegeln kleiner Schichtdefekte: Ausgefallene Korrosionsprodukte von Mg verschließen vorübergehend Schichtdefekte und verhindern bzw. verzögern das Vordringen des Korrosionsmediums zum Stahl. T2 - 15. Sommerkurs Werkstoffe und Fügen am Institut für Werkstoff- und Fügetechnik CY - Magdeburg, Germany DA - 12.09.2014 PY - 2014 SN - 978-3-940961-85-3 SP - 187 EP - 196 AN - OPUS4-31476 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 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 SN - 978-3-89746-159-8 SP - O EP - 7473, 384 AN - OPUS4-31482 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Thoralf A1 - Burkert, Andreas A1 - Heyn, A. A1 - Balzer, Martin A1 - Fenker, M. T1 - Investigation on the improved corrosion behavior of TiMgN hard coating on steel substrate T2 - EUROCORR 2015 - European corrosion congress CY - Graz, Austria DA - 06.09.2015 KW - Hard coatings KW - TiMgN KW - Corrosion PY - 2015 SP - paper 11.1_693 AN - OPUS4-34618 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -