An investigation of the friction and wear behaviors of micrometer copper particle- and nanometer copper particle-filled polyoxymethylene composites

Micrometer and nanometer copper particle-filled polyoxymethylene composites (coded as POM-micro Cu and POM-nano Cu, respectively) were prepared by com pression molding. The compression strength and tensile strength of the comp osites were evaluated with a DY35 universal materials tester. An RFT-III re ciprocating friction and wear tester was used to examine the tribological p roperties of the composites. The elemental compositions in the transfer fil ms and the chemical states of the elements in the composite-worn surfaces w ere analyzed with electron probe microanalysis and X-ray photoelectron spec troscopy, while the surface morphologies were observed with scanning electr on microscopy. It was found that Cu(-CH2-O-)(n) was produced in sliding of a POM-nano Cu pin against an AISI 1045 steel block and Cu2O was produced in sliding of a POM-micro Cu pin against the same counterface. POM-micro Cu e xhibited higher copper concentration in the transfer film compared with POM -nano Cu, and the transfer film of the former was thick and patchy compared with that of the latter. It was also found that micrometer and nanometer c opper particles as fillers in POM exhibit a distinctive size effect in modi fying the wear mechanisms of the composites. In other words, the wear mecha nism of POM-micro Cu is mainly scuffing and adhesion, while that of POM-nan o Cu is mainly plastic deformation. (C) 2000 John Wiley & Sons, Inc.