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Wels, Austria

Stefenelli M.,Materials Center Leoben Forschung | Todt J.,University of Leoben | Riedl A.,Materials Center Leoben Forschung | Ecker W.,Materials Center Leoben Forschung | And 4 more authors.
Journal of Applied Crystallography | Year: 2013

Novel scanning synchrotron cross-sectional nanobeam and conventional laboratory as well as synchrotron Laplace X-ray diffraction methods are used to characterize residual stresses in exemplary 11.5μm-thick TiN coatings. Both real and Laplace space approaches reveal a homogeneous tensile stress state and a very pronounced compressive stress gradient in as-deposited and blasted coatings, respectively. The unique capabilities of the cross-sectional approach operating with a beam size of 100nm in diameter allow the analysis of stress variation with sub-micrometre resolution at arbitrary depths and the correlation of the stress evolution with the local coating microstructure. Finally, advantages and disadvantages of both approaches are extensively discussed. © 2013 International Union of Crystallography Printed in Singapore - all rights reserved.

Strobl V.,Rubig GmbH and CO KG | Gebeshuber A.,Rubig GmbH and CO KG | Muller T.,Rubig GmbH and CO KG | Irretier O.,Industrieberatung fur Warmebehandlungstechnik
Elektrowaerme International | Year: 2010

The demands of the engine, transmission and power train industry concerning wear and also corrosion resistance of their components have strongly increased in the last years. Conventional processes like carburizing and gas nitriding are facing to some extent their limits. Pulsed plasma nitriding on the other side arouses more and more interest in this industry as especially the life-time of these components can be increased dramatically due to the special layer composition of this surface treatment process. Pulsed plasma nitriding is also a very interesting economical option as normally the final, very cost-intensive hard machining can be omitted. Furthermore, pulsed plasma nitriding has considerable advantages concerning the environment compared to the other heat treatment processes. It is the only surface heat treatment that can be easily integrated into mechanical manufacturing as there is no open flame and nearly no waste gas. The lecture will show the essential findings that company Ruebig has gained and tested in the past few years together with the University of Wels and the company Magna/Steyr.

Dipolt C.,Rubig GmbH and CO KG | Mori G.,University of Leoben
NACE - International Corrosion Conference Series | Year: 2014

The steel grade SAE 4140 has been nitrided and coated with amorphous diamond like carbon (DLC) from type a-C:H:Si. The nitriding and coating with diamond like carbon was carried out in a plasma assisted nitriding furnace which is extended by plasma assisted chemical vapour deposition for a-C:H:Si coating. The nitriding before coating has been done to increase adhesion and reduce the hardness gradient between the diamond like carbon layer (810-1125HV) and the sample material (325HV). The temperature of the coating process has been varied, from 400 to 550°C. These different samples have been analysed to obtain corrosion resistance data using potentiodynamic polarisation and a salt spray test. The chemical composition of the a-C:H:Si coating has been analysed using glow discharge optical emission spectroscopy (GDOES). Hardness of the coating was identified with nanoindentation. Scanning electron microscopy coupled with energy dispersive x-ray spectroscopy was utilized to analyse the structure and defects on samples after corrosion test. © 2014 by NACE International.

Forsich C.,Upper Austria University of Applied Sciences | Dipolt C.,Rubig GmbH and CO KG | Heim D.,Upper Austria University of Applied Sciences | Mueller T.,Rubig GmbH and Co KG Anlagentechnik | And 3 more authors.
Surface and Coatings Technology | Year: 2014

Chromium plating is a well-established technique for corrosion and wear protection. One essential problem inherent with this process is the use of toxic and carcinogenic hexavalent chromium. A potential substitution of hard chromium with thick a-C:H:Si coatings (amorphous Si-doped hydrogenated carbon) has been studied. a-C:H:Si films represent chemical and electrochemical inert hard coatings with very favorable tribological and corrosion properties. Up to now it was only possible to deposit thin DLC-films because of the high intrinsic stress in the films.A series of laboratory tests including scratch, pin-on-disk and electrochemical corrosion measurements were performed in order to compare the performance of hard chromium and a-C:H:Si. By depositing a-C:H:Si films without using hazard chemicals in a dc-pulsed hot wall plasma system coatings with thicknesses up to 58. μm were produced. These coatings exhibit elastic properties during scratching at the beginning and get a self-sustaining behavior with increased coating thickness resulting in a high load carrying capability. For hard chromium coating cracking was already observed at the very first stage of testing.Sliding tests under unlubricated conditions of a-C:H:Si films showed superior friction performance (friction coefficient μ=0.02 versus μ=1.1) and excellent wear resistance of the coating and the counterpart (wear rate 7*10-8mm3/N-1m-1 versus 6*10-5mm3/N-1m-1) compared to hard chromium. Further potentiometric observations demonstrated a much better corrosion resistance for thick a-C:H:Si coatings than hard chromium (Ecorr -0.28V vs. Ecorr -0.52V). © 2013 Elsevier B.V.

Kommenda M.,Upper Austria University of Applied Sciences | Kommenda M.,Johannes Kepler University | Burlacu B.,Upper Austria University of Applied Sciences | Burlacu B.,Johannes Kepler University | And 4 more authors.
27th European Modeling and Simulation Symposium, EMSS 2015 | Year: 2015

We present an approach for estimating control parameters of a plasma nitriding process, so that materials with desired product qualities are created. We achieve this by solving the inverse optimization problem of finding the best combination of parameters using a real-vector optimization algorithm, such that multiple regression models evaluated with a concrete parameter combination predict the desired product qualities simultaneously. The results obtained on real-world data of the nitriding process demonstrate the effectiveness of the presented methodology. Out of various regression and optimization algorithms, the combination of symbolic regression for creating prediction models and covariant matrix adaptation evolution strategies for estimating the process parameters works particularly well. We discuss the influence of the concrete regression algorithm used to create the prediction models on the parameter estimations and the advantages, as well as the limitations and pitfalls of the methodology.

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