Thermal, Hardness, and Tribological Assessment of PEEK/CoCr Composites

Poly(ether-ether-ketone) (PEEK) is a high-performance thermoplastic with excellent mechanical strength, thermal stability, and chemical resistance, making it attractive for applications like biomedical implants and prostheses. However, neat PEEK suffers from a high friction coefficient and pronounced wear in sliding contacts. In this work, composites of PEEK with Cobalt–Chromium (CoCr) alloy powder were fabricated by centrifugal powder compaction and vacuum sintering. Four composite compositions, with weight percentages of 10%, 20%, 30%, and 40% of CoCr, were produced. Comprehensive characterization was conducted, including particle size distribution analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy, differential scanning calorimetry, thermogravimetric analysis, microhardness testing, and ball-on-disk tribological testing against a steel counterface. The PEEK/CoCr composites showed uniform dispersion of CoCr particles in the PEEK matrix. Thermal analysis indicated that the addition of CoCr did not significantly alter PEEK’s melting temperature or thermal stability with residual weights corresponding closely to the filler fractions. The microhardness of the composites increased with CoCr content, with the 40% CoCr composite showing a 35% increase in hardness compared to the neat PEEK. In ball-on-disk tests, all PEEK/CoCr composites exhibited lower wear rates than neat PEEK, owing to the hard CoCr particles reinforcing the polymer. The coefficient of friction was in the typical range for PEEK sliding on steel for all composites, as the metallic filler does not provide lubrication; however, the improved hardness and load-bearing capacity of the composites led to reduced wear depth and volume loss. Overall, the PEEK/CoCr composites demonstrate enhanced hardness and wear resistance while retaining PEEK’s favorable thermal properties, suggesting their potential for applications requiring better tribological performance than unfilled PEEK.