PEEK-matrix composites containing different content of natural silica fibers or particulate lithium‑zirconium silicate glass fillers: coefficient of friction and wear volume measurements

The purpose of this work was to evaluate the friction and sliding wear behavior of poly-ether-ether ketone (PEEK) matrix composites containing natural amorphous silica fibers (NASF) or particulate lithium‑zirconium silicate (LZSA) glass-ceramics. PEEK and PEEK containing different weight content (10, 20, and 30 wt%) of LZSA or NASF were processed by hot pressing. Reciprocating sliding wear tests were performed on the specimens in artificial saliva solution against an alumina ball on 30 N normal force. Tests were performed at 1 Hz sliding frequency, and at 4 mm stroke length in artificial saliva solution. The worn surfaces were morphologically inspected by field emission guns scanning electron microscopy (FEGSEM) to calculate the wear volume. Coefficient of friction values recorded on PEEK or PEEK-NASF composites against alumina were lower than those on PEEK-LZSA composites. The presence of LZSA particles negatively affected the wear resistance of the PEEK composites. On sliding tests mimicking oral conditions, PEEK composites containing NASF revealed low friction and high wear resistance close to that one exhibited by PEEK. Such results can stimulate further studies on the processing and tribological characterization of PEEK composites including different percentage of natural amorphous silica fibers.