Microtribology of silicon,oxide, and carbide surfaces

This paper presents an overview of the microtribological properties of silicon oxide, sapphire, and titanium carbide surfaces as well as a self‐assembled monolayer with respect to their application in microsystems. Testing was performed with a reciprocating microtribometer with normal loads in the micronewton to millinewton range. Silicon and titanium carbide balls were used as counterbodies. For silicon oxide, sapphire and a perfluorodecyltrichlorosilane self‐assembled monolayer (FDTS), the microfriction corresponds to the water contact angle when the smoother titanium carbide ball or the relatively rougher silicon ball was used as a counterbody. Microfriction measurements performed on tribopairs of the same material, but having different roughnesses, showed that the friction of the rougher tribopairs is lower than that of the smoother ones. Interestingly, in the microforce regime, reduction in friction was significant and almost as much as when hydrophobic self‐assembled monolayers are applied on smooth surfaces. This investigation showed that comparative microtribological investigations between different material systems can be very challenging due to the fact that comparable roughness values on samples and countersamples are difficult to realize. Copyright © 2006 John Wiley & Sons, Ltd.