As the automotive industry shifts toward hybrid and alternative drive concepts like electromobility, it remains vital to continuously improve internal combustion technology. Internal combustion applications represent the largest portion of transportation technologies. Continuous development and improvement of passenger car engines focus on reducing emission by weight reduction and enhanced efficiency. To gain a competitive advantage in present and future engines, Mercedes-Benz AG developed the innovative NANOSLIDE Ò technology that uses thermal spray technology, i.e., twin wire arc spray, to coat the internal diameter of cylinder bores. Computational fluid dynamics (CFD) simulation is utilized to investigate the complex gas flow in the cylinder bore of the crankcase during the coating process. Extensively experiments are performed and analyzed to compare the results with the quantitative analysis in order to enhance the properties of the cylinder coating. The combination of simulation and coating experiments led to the development of uniform distributed layer adhesion strength throughout the length of the cylinder bore.

This paper presents a novel approach to enhance the corrosion resistance of cylinder-bore coatings for internal combustion engines by changing surface characteristics and microstructures of the coating and utilizing alternative materials. The approach of this study refers to the knowledge of the complex gas-flow conditions during the internal-diameter coating of cylinder-bores using a twin-wire arc-spray process. Selective influencing of the gas flow enables the preparation of sample coatings with inhomogeneous and more homogeneous microstructures and surfaces. The various coatings were exposed to corrosive environments using the Kesternich testing method and an alternating immersion test. Significant improvements in corrosion resistance have been demonstrated by up to 50 % through altering the microstructure of the coating and almost 100 % by additional changing the spraying material. The study reveals an increased protection of cylinder-bore coatings against corrosive attacks through a homogeneous microstructure prepared in oxygen-poor coating conditions.

In this paper, the principles of computational fluid dynamics are used to simulate the complex gas flows in the cylinder bore of an automotive engine during internal-diameter twin-wire arc spraying. A number of experiments are conducted as well and the results are presented and analyzed in order to optimize the properties of the coating. The combination of simulation and experiments led to the development of a process that achieves uniform layer adhesion strength over the length of the cylinder bore.