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For years the chromium ceramic coating has proved to have good resistance when applied for Diesel engines subjected to severe operational conditions. However, given the constant increase of engine demands and the concern of low gas emissions, higher wear resistance and durability have been required. As a consequence, MAHLE has developed a new chromium-based coating, which balances the cost competitiveness of chromium-based coatings with enhanced performance. The new coating, named NanoBor Chromium, consists of reinforced chromium coating with ultrafine cBN particles (cBN = cubic boron nitride) embedded inside micro-fissures created by a controlled multi-stage electrochemical process. The tests in MDD engines (MDD=Medium-duty diesel) and HDD engines (HDD= Heavy-duty diesel) have demonstrated the excellent performance of NanoBor Cr as new alternative for heavily demanded application.

The demand for higher output performance engines has lead to the increase of PCP (Peak Cylinder Pressure) and more aggressive engine designs for cylinder liners, mainly for new heavy duty engines developments where low cost components are been introduced. Such trends have generated demands to adequate the liner design by improving its material properties by changing its chemical composition, new materials data or even by introducing more accurate casting manufacturing process. Therefore, there is a clear tendency to development more and more alternative solutions that combine a certain technical high-value added and low cost. The most important material properties for cylinder liners are the ultimate tensile strength (UTS) and the fatigue tensile strength. Both parameters confer to the cylinder liners, especially for wet top flanged designs, the ability to survive under high mechanical and thermal load conditions even with reduced wall thickness.

The tendency to use aluminum alloys to replace conventional gray cast irons (GCI) materials in engine blocks of passenger cars is gaining more and more importance driven by reduction of engine weight to achieve expectation for lowering fuel consumption and CO₂ emissions. Cast-in cylinder liners are commonly applied inside of aluminum engine blocks with designs of the outer surface usually selected through analysis of the aluminum casting process (e.g., high pressure die casting, precision sand cast), geometry complexity, thermal and mechanical loads. A good quality of clamping (bonding and shear strength) between the cast-in cylinder liner and aluminum block might guarantee a reliable heat transfer and thus low bore distortion. The good clamping can also contribute to improve the final machining of the liner after block casting. The most effective variants of cast-in cylinder liner designs were selected for the evaluation of clamping performance.