Tim Königstein

Development of Novel Fe-Based Coating Systems for Internal Combustion Engines

Nowadays, combustion engines are the most common way to power vehicles. Thereby, losses occur due to cooling, exhaust gas and friction. With regard to frictional losses, highest potentials for optimization can be found in the tribological system of the inner surface of combustion chamber and piston ring. Besides friction, corrosive stress increases, e.g., due to utilization of exhaust gas recovery. In order to save energy, reduce emissions and enhance the life span of combustion engines, the demand for innovative coating material systems, especially for the inner surface of combustion chamber, increases. This study focuses on the development of innovative iron-based coating materials for the combustion chamber. As a first step, the plasma transferred wire arc and rotating single wire arc (RSW) technologies were compared using 0.8% C-steel as a reference. Subsequently, RSW was used for coating deposition using an innovative iron-based feedstock material. In order to improve wear and corrosion resistance, boron and chromium were added to the feedstock material. After deposition, different honing topographies were manufactured and compared under tribological load. Furthermore, electrochemical corrosion tests were conducted using an electrolyte simulating the exhaust gas concentrate. Especially with regard to corrosion, the novel coating system FeCrBMn showed promising results.

Influence of feedstock materials and spray parameters on thermal conductivity of wire-arc sprayed coatings

To manufacture a protective coating with high thermal conductivity on drying cylinders in paper production machines, a FeCrB-cored wire was developed, and the spraying parameters for wire-arc spraying were optimized in this study. The conventional engineering materials FeCrAl and FeCrMo coatings were produced as the reference coatings under the same experimental condition. It has been shown that the oxide content in coating influences the thermal conductivity of coating significantly. The FeCrB coating exhibits a relative higher thermal conductivity due to the lower oxide content in comparison with conventional FeCrAl and FeCrMo coatings. Moreover, the oxidation of in-flight particles can be reduced by decreasing the standoff distance contributing to the increase in the thermal conductivity of coating. Total energy consumption of a papermaking machine can be significantly reduced if the coatings applied to dryer section exhibit high thermal conductivity. Therefore, the FeCrB coating developed in this study is a highly promising coating system for drying cylinders regarding the improved thermal conductivity and low operation costs in paper production industry.