Scratch evaluation on a high performance polymer

Abstract

The scratching process is a well know concept and is usually defined as a kind of surface abrasion, where plastic deformation is promoted by relative friction between soft phase and a hard intender. It is necessary to reduce material loss to minimum or even to reach zero to have an efficient and effective functionality of the materials. Polymers being highly sensitive to wear and scratch damage, their various modes of deformation such as, tearing, cracking, delamination, abrasive and adhesive vary with a narrow range of contact variables like applied normal load, sliding velocity, interfacial lubrication and testing temperature. This is particularly important when these materials are used to improve the tribological performance by adding various types of fillers such as, carbon fibers, graphite,PTFE, TiO2, and ZnS are added. The polymers with nanocomposites have the advantages over micro- composites from the viewpoint of wear and scratch damage, the underlying mechanism of damage in the single asperity mode is still unclear. The goal of this study is to experimentally evaluate the deformation modes and the friction processes involved during the scratching of polymer reinforced with nanocomposites. The scratches were produced on the semicrystalline polyetheretherketone (PEEK) surface using a Rockwell C diamond indenter was pressed onto the flat surface of each sample, until a complete loadindentation depth-curve was achieved. These scratched surfaces were assessed with optical microscope and scanning electron microscope (SEM) for prevailing deformation mechanism and the geometry of damage.