Time filter

Source Type

Wiener Neustadt, Austria

Curkovic L.,University of Zagreb | Curkovic H.O.,University of Zagreb | Salopek S.,ACT Research GmbH | Renjo M.M.,University of Zagreb | Segota S.,Ruder Boskovic Institute
Corrosion Science | Year: 2013

Nanostructured TiO2 thin films were deposited on AISI 304 austenitic stainless steel by sol-gel process, dip coating technique. Influence of the number of layers, addition of polyethylene glycol (PEG) in initial sol, morphology and the surface roughness parameters of titania films on corrosion resistance of coated stainless steel were examined. Prepared films were characterized by SEM-EDS and AFM analysis. Electrochemical corrosion behavior of the coated stainless steel substrates was evaluated in simulated marine environment in 3wt.% aqueous NaCl solution by electrochemical impedance spectroscopy (EIS) and in 0.5M aqueous HCl solution by potentiodynamic polarization. © 2013 Elsevier Ltd. Source

Veinthal R.,Tallinn University of Technology | Sergejev F.,Tallinn University of Technology | Zikin A.,Tallinn University of Technology | Zikin A.,ACT Research GmbH | And 2 more authors.
Wear | Year: 2013

The conventional Fe-Cr-C overlay is studied due to the lack of information regarding the response of this material system to impact wear conditions. Previously the same material system has been successfully used in erosion wear conditions. The high stress abrasive impact wear resistance and low and high surface fatigue wear behaviour of a Fe-Cr-C overlay (FeCrC-matrix) produced by plasma transferred arc welding (PTA) were studied.The overlays with varied PTA hardfacing process cooling parameters were tested. The cooling parameters were as follows: (1) active cooling-application of gas cooling of substrate during the welding process; (2) passive cooling-application of copper plate under substrate with constant temperature of 20. °C and (3) standard-cooling in the air. Different cooling time leads to differences in microstructure and formation of residual stresses (surface cracks, etc.).The abrasive impact testing reveals the difference in the overlays response to the cyclic stressing at high impact energy. The surface fatigue wear (SFW) testing is accompanied by the abrasive impact wear (AIW) testing. The SFW incorporates cyclic loading of the overlays surface with spherical indenter with radius of 10. mm at high loads, while in AIW testing the specimens are bombarded almost in normal direction with granite gravel particles (diameter of <6. mm) with the energy in the range of 0.14-0.52. J.The study proposes the relation between high energy impact/abrasive wear behaviour and the surface fatigue wear behaviour of Fe-Cr-C hardfacings produced under varying cooling conditions. © 2013 Elsevier B.V. Source

Felkel Y.,ACT Research GmbH | Dorr N.,ACT Research GmbH | Glatz F.,University of Applied Sciences Wiener Neustadt | Varmuza K.,Vienna University of Technology
Chemometrics and Intelligent Laboratory Systems | Year: 2010

The most common analyses carried out to assess gas engine oil quality include determination of viscosity, total base number (TBN), and total acid number (TAN). TAN has been considered to be an important indicator of oil quality, specifically in terms of defining oxidation and the extent of acidic contamination of used oils. TAN can be determined by potentiometric titration, and typical values for used oils can reach up to 4 mg KOH/g. A more convenient approach for the determination of TAN is based on infrared (IR) spectral data and multivariate regression models. We developed partial least-squares (PLS) models for the determination of TAN using IR data measured from monograde mineral gas engine oils (SAE 40, medium ash) that have been used in sewer and wood gas engines run with gaseous fuels from a sewage plant and a wood gasification plant, respectively. The final model performance was 0.07 mg KOH/g for the standard error of prediction (SEP). Essential for the development of powerful empirical models was an appropriate variable selection by combining expert knowledge, biPLS or dyn-biPLS, and a genetic algorithm. The optimum complexities of the models (the number of PLS components) and their prediction performances have been estimated by repeated double cross validation (rdCV). © 2009 Elsevier B.V. All rights reserved. Source

Linz M.,ACT Research GmbH | Linz M.,Saarland University | Winkelmann H.,ACT Research GmbH | Hradil K.,Vienna University of Technology | And 2 more authors.
Engineering Failure Analysis | Year: 2013

Stresses in the near-surface area can form cracks which join together, propagate and combine, forming pits due to material spall-off. The stresses causing the cracks are not only influenced by external forces, residual stresses stored in the material also play an important role. Moreover, these residual stresses can vary during the lifetime of the sliding components. Cracks are found in the wear tracks of linear oscillating ball contacts on AISI 4140 steel. The crack propagation at the surface is longitudinal to the sliding direction. Residual stress analysis by X-ray diffraction (XRD) shows that normalized samples develop tensile stresses in the near-surface zone of the wear track. Residual stresses are found to be higher transversal to the moving direction than longitudinal. © 2013. Source

Katsich C.,ACT Research GmbH | Badisch E.,ACT Research GmbH
Surface and Coatings Technology | Year: 2011

Within this work, the effect of carbide degradation in a WC/W2C reinforced Ni-based hardfacing was assessed under abrasive and combined impact/abrasive conditions. In view of the above, a WC/W2C reinforced Ni-based hardfacing was deposited by plasma transferred arc (PTA) welding using different welding currents. Microstructure was characterised by quantitative metallography to determine specific structural parameters: mean carbide diameter and carbide area fraction. Scanning electron microscopy (SEM, EDS) and X-ray diffraction (XRD) were also used to characterise carbide dissolution mechanism. Tribological behaviour was determined with a 3-body abrasion test according to ASTM G65 and with a cyclic impact/abrasion test (CIAT). Results showed significant carbide degradation with increasing welding current, resulting in a significant reduced primary carbide content and carbide diameter. Reduced carbide content indicated a significantly wear rate increase under pure 3-body abrasion conditions. Specific wear energy was determined under pure abrasive condition and showed significant dependence on the primary carbide content. However, wear rates under combined impact/abrasion were at constant level due to the reduction of the brittle primary carbide content. © 2011 Elsevier B.V. Source

Discover hidden collaborations