Plasma sprayed chrome carbide coated piston rings are currently used in production engines at Caterpillar. Such a demonstrated success of plasma sprayed coatings make this process attractive. Plasma sprayed coatings with the potential to meet the wear and friction goals will be optimized for adherence. In addition we will investigate appropriately combined chemical species, especially molybdenum and cobalt, capable of generating self-lubricating surface layers of adherent oxide complexes at temperatures to 800 °C.

Titanium nitride and titanium carbide CVD-PVD coatings are widely used on cutting tools for extended wear life. Preliminary work at Caterpillar with a PVD titanium nitride coated piston ring showed promising wear characteristics. Recent published data reported that dramatic Increases in the adhesion and wear life of PVD coatings can be achieved by ion implantation of the surface with certain materials such as titanium and boron. This concept will be explored for improving the adherence and wear of several CVD-PVD coatings.

The enameling process results in glass base coatings with excellent adherence. Coefficients of friction for glass materials are low and recent work by Solar Turbines, Inc., a subsidiary of Caterpillar, has shown that these glass base coatings can be reinforced with particulates of hard wear resistant particles. In this investigation, (to be performed at Solar and the University of Illinois) high temperature, highly adherent enamels will be developed and reinforced with hard particles.

Statistically designed experiments will be used to optimize the coating processes for adherence. The optimized coatings will be screened for wear and friction with a Pin-on-Disk apparatus using solid pins made of ceramic running against coated disks. After screening, the best coatings will be further optimized for wear and friction and then fully characterized for wear, friction, oxidation, thermal shock, adherence, uniformity, and for coating/substrate interactions.

Materials To Be Investigated To Develop Adherent. Wear Resistant Coatings Using The Plasma Spray Process Are Shown Below.

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