Tribology of a novel UHMWPE/PFPE dual-film coated onto Si surface

A novel wear resistant polymer composite layer is coated onto the Si surface. The first layer consists of ultra-high molecular weight polyethylene (UHMWPE) film and the second top layer is made of perfluoropolyether (PFPE). These two layers are coated onto Si using a simple dip-coating technique. This particular combination of dual-film has reduced the coefficient of friction by at least 6 times and increased the wear resistance of the Si surface by at least 1000 times with very minimum to no sign of wear debris formation. The tribological tests are carried out using ball-on-disk tribometer employing 4 mm diameter Si3N4 ball as the counterface, at a nominal contact pressure of similar to 370 MPa. The UHMWPE/PFPE dual-film provides hydrophobic surface with very high water contact angle (134 degrees). Finally, this dual-film may find applications in reducing wear and stiction of micro-components (such as micro-electro-mechanical systems) made from Si. (c) 2005 Elsevier B.V. All rights reserved.