Tenneco's powertrain laser process creates low-friction piston rings, extending engine overhaul intervals
Shanghai, December 3, 2019 … Tenneco (NYSE: TEN) The laser process being developed by the Powertrain Division can provide unprecedented wear resistance for future large bore engine (LBE) piston rings . This technology provides an environmentally friendly, long-term alternative to electroplated coatings. It is also the latest result of Tenneco Powertrain's continuous research on new surface treatment technologies to meet the future development of engines and fuels in marine and industrial fields challenge. Tenneco Powertrain ’s DAROS®, Rotocap®, GOETZE® large-bore piston rings and industrial seal rings, all of which have made their debut in the maritime field with innovative products and technological achievements in the China International Maritime Exhibition N3 Hall C3Z booth, transforming the marine industry Escort.
Prospective Technology, Tenneco, Tenneco Laser Process
The market trend of reducing operating costs and saving energy and reducing emissions is spurring future design changes for two- and four-stroke engines, which will also cause piston rings to face higher mechanical and thermal loads. At the same time, piston ring life is expected to be 24,000 hours or more, driven by the need to reduce friction, reduce fuel consumption, and extend overhaul intervals.
From 2020, the “Sulfur Limitation Order” will be implemented globally, and the market share of gas and dual fuel engines will also increase, which will bring more tribological challenges to piston rings and cylinder liners. Therefore, high dimensional stability of hybrid materials and coatings with low coefficients of friction, high wear resistance, and low wear rates for piston rings and cylinders are essential to address these challenges.
"Tenneco Powertrain focuses on the emerging trends in the global marine market and is committed to the development of advanced technologies." Said Peter Arndt, director and general manager of the piston ring division of Tenneco's large-bore engine. The process opens up even more possibilities, and it can be used in a wide range of basic materials, including gray and ductile iron. "
Tenneco Powertrain is developing multiple laser processes, including laser structuring, laser remelting, laser alloying, and laser deposition welding. Laser deposition welding has been widely used as a coating process to replace hard chromium layers, and nickel-based and cobalt-based alloys are used instead of dispersed hard materials. However, in the future, in order to meet the needs of piston ring surfaces, new coating materials are still needed, that is, iron-based and nickel-based materials alloyed with hard phases and carbide-forming elements.
Laser remelting can significantly change the surface properties of gray cast iron materials, thereby greatly improving their wear resistance. The high-energy laser melts the iron, and the iron is spontaneously quenched by the movement of the laser focus, resulting in a white solidified bainite material structure containing Fe3C with a hardness of approximately 800 HV. The size and distribution of the Fe3C hard phase can be flexibly adjusted by laser energy injection. Laser remelting and laser deposition welding can produce metallurgical bonding between the substrate and functional coating materials.
Accumulation based on rich experience
Tenneco Powertrain has previously developed many successful and innovative surface treatment technologies for large-bore engine piston rings, and the laser process will become the latest innovative surface treatment process.
Electroplated hard chrome coatings, such as chrome ceramic coatings (CKS ®), contain up to 10% embedded 2-5μm alumina particles, which can significantly improve the wear resistance and scratch resistance of the piston ring end face. At the same time, thermal spray coating Technology can produce higher hard phase content (up to 60% by volume). Compared with CKS®, GOETZE® diamond coating (GDC®) is more wear-resistant. The new GDC®60 coating of Tenneco Powertrain shows a very low coefficient of friction when the engine is running. Extremely high abrasion resistance and low cylinder wear.
CrN coating or CrON coating PVD (physical vapor deposition) hard coating shows high wear resistance and high scratch resistance under high thermal load: the coating thickness is limited to 50 μm by the application process, and the new laser remelting method can The coating thickness reaches 1mm, which prolongs the service life of the piston ring.
"To date, initial tests on large-bore engine piston rings with laser-remelted end faces have shown very good results." Arndt said, "This solution for end-face surface strengthening can Both sides are combined with all existing common working surface coatings to provide high load resistance and long service life. "
Pre-series production using piston ring end face laser remelting has begun in 2018 with long-term testing on running engines. In addition, the development of laser-deposited welding materials for piston ring working surfaces is currently underway and the first engine test is expected in 2020.