EAPSI: Incorporation of Nano-Sized Diamonds in Advanced Composite Coatings for Reduction of Friction and Wear

Nieto Andy, Davis CA

Investigators

Abstract

The proposed research will attempt to fabricate advanced coatings with reduced friction and wear, as compared to commercially used materials. Tungsten carbide / cobalt coatings are used today in a wide range of sectors including the aerospace, automotive, and energy industries. The incorporation of nano sized diamonds into these materials to form advanced composite coatings is envisioned to improve the wear resistance and reduce friction. The reduction of friction is critically important to improving energy efficiency; for example, it is estimated that 33% of fuel energy in automobiles is consumed in overcoming frictional losses. The proposed research will be conducted at Yonsei University in South Korea in the laboratory of Dr. Dae Eun Kim. The Center for Nano-Wear directed by Dr. Kim has world class facilities for accessing the friction and wear performance of a variety of materials under several types of environments. The use of nanodiamonds is expected to address several key concerns in tungsten carbide / cobalt coatings. The wear performance of these coatings is dependent on achieving an optimal combination of strength (e.g. hardness) and ductility (e.g. toughness). These properties are often mutually exclusive as they are dependent on constituent phases which are typically either hard and brittle or soft and tough. The use of diamonds is expected to increase hardness while simultaneously providing toughening by inhibiting the formation of brittle phases. The diamonds are expected to act as a source of carbon during the high temperature processing used to make the coatings, which will inhibit the decarburization of tungsten carbide into brittle phases. Diamond also has excellent thermal conductivity which would be beneficial to wear performance in high temperature environments. Wear tests will be conducted to evaluate the performance under simulated loading conditions and also to elucidate the effects of the nanodiamonds on the material properties.