Advanced Coatings for Improved Diesel Engine Durability and Efficiency

Current-generation heavy-duty diesel engines typically exhibit an engine efficiency of about 45%, the remaining energy used for running auxiliary systems or lost as heat or friction. Heavy-duty vehicles lose on average about 20% of the fuel energy inside the combustion chamber as heat to the coolant and 30% as heat to the exhaust. Increasing the efficiency of diesel engines while simultaneously improving engine performance will require higher engine temperatures with lower heat rejection (LHR).A key objective for development of the LHR engine has been the prospect of decreasing the engine’s cooling load. Achieving this goal will require development of new materials such as advanced wear-resistant coatings that are capable of sustaining severe operating environments while conferring improved friction response. Coatings applied to engine components such as piston rings and cylinder liners can enable increased combustion pressures and temperatures, while reducing overall heat loss to the coolant, with direct benefit to engine performance and efficiency. With reduced friction between contacting surfaces, less energy is required to overcome frictional losses during start-up and/or operation, thereby yielding improved efficiency. The economic impact of improving the fuel efficiency of Class 8 diesel trucks is enormous. Considering the 3.6 million class 8 diesels currently on the road in the U.S., each driven an average of 68,000 miles per year with typical fuel cost of $3/gallon, the cumulative annualized cost of fuel is on the order of $113B. Assuming improved coatings increase fuel economy by 5%, with a 10% market penetration, the net annualized savings amounts to ~ $500M. This proposal seeks to develop and apply a new high-performance coating for engine components, based on a family of materials that has been shown in preliminary laboratory tests to exhibit extreme resistance to wear, while conferring low friction, with the potential for long-term operation at temperatures exceeding 1000°C. This material is comprised of a novel refractory boride-based compound.The material is expected to confer superior wear resistance while maintaining a coefficient of friction on the order of 0.09 under high contact stress levels of 1 GPa or higher. Specific technical objectives of the proposed Phase I project are four-fold: i) Determine the most promising composition within the proposed family of materials that confers the highest wear resistance and lowest friction in bench-scale tribology tests, ii) Demonstrate the potential for this material to be deposited on ferrous-based substrates using magnetron sputtering, iii) Gather initial data on CTE and bonding issues with grey cast iron substrates, and iv) Secure arrangements with a major diesel engine manufacturer and commercial OEM to test the coatings in a follow-on Phase II effort. Realization of these objectives will provide a path toward successful prototype development in Phase II and commercialization of the technology in Phase III.Commercial applications for this technology begin with improved efficiency in long-haul diesel engines along with reduced maintenance intervals, which translates to reduced shipment costs for consumer goods. As our society becomes increasingly dependent on e-commerce and the associated point-to-point delivery of essential products, the reliability and costs associated with the logistics need to be addressed. HB-BAM coatings will also be adaptable to conventional engines, offering additional means to achieve better economy and performance which consumers are demanding. This will in-turn improve the competitiveness of domestic auto manufacturers.