Structure and tribological properties of composites based on a Novolac matrix with Ni[sbnd]P electrolytic coating

Abstract

In this study, wear behavior of graphite and glass fiber reinforced Novolac hybrid polymer composites with electrolytic NiP coated surfaces were investigated. First of all, 40 wt% graphite and 30 wt% glass fiber added Novolac composite powders were obtained by mixing with a mixer, and then hybrid composite samples were obtained by hot pressing the composite powders in a steel mold. Then, electrolytic NiP coating process was applied to the hybrid composite surfaces. The tribological properties of coated and uncoated samples were compared after the applying the block-on-ring wear test method. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used for wear surface and debris analysis. The Tg temperature of the electrolytic NiP coated samples increased by about 16 °C compared to the uncoated samples. The hardness value of the obtained NiP coating layer was determined as approximately 2 GPa. On the other hand, NiP coated samples showed approximately 2 times less wear loss and 40 % lower coefficient of friction than those of the uncoated composite samples. While the dominant wear mechanism was found as adhesive in uncoated samples, it was detected as abrasive and adhesive together in NiP coated samples.