METALLIC WEAR-RESISTANT COATINGS FOR CARBON-FIBER EPOXY COMPOSITE ROLLS

Carbon fibre reinforced polymer rolls are an interesting alternative t o steel or aluminium rolls for the paper, textile and foil industries on account of their great stiffness and very low inertia. However, the ir application is impeded by insufficient wear resistance. In cooperat ion with a roll manufacturer, a technology was developed to apply a co ating system of superior wear resistance to these rolls. The process c onsists of several steps: (1) microroughening of the substrate surface , (2) deposition of nucleation sites, (3) electroless deposition of an NiP coating, (4) chrome plating. The most critical area of this coati ng system is the interface polymer-NiP layer. Because the van der Waal s bonds are too weak to give sufficient adhesive strength, the substra te surface has to be prepared very carefully for optimum mechanical in terlocking by grit blasting. In this way an adhesive strength up to 20 MPa could be achieved, as measured by pull-off tests. This often exce eds the cohesive strength of the carbon fibre/epoxy composite. Apart f rom the process technology, the paper also adresses the characterizati on of the coatings with respect to microstructure, surface quality and wear resistance.