Processing and characterizations of polycarbonate/alumina nanocomposites by additive powder fed friction stir processing

The powder fed friction stir process (FFSP) is a new and attractive solid-state manufacturing technique that enables the fabrication of polymer matrix nanocomposites (PNC). Herein, we present the fabrication of polycarbonate (PC)-based nanocomposites by in-situ injection of colloidal alumina nanoparticles (<100 nm) into the plasticized polymer under stir friction of a steel tool. Microstructural features and mechanical durability of the prepared nanocomposites were studied. The mechanical properties of the processed materials including hardness, tensile strength, flexural strength, and impact energy were elaborated. The tensile strength of PNC in the longitudinal direction was-73 MPa, which was higher than the PC matrix by 109%. However, a lower bending strength (-48 MPa) compared with PC was measured. Fractographic studies determined the presence of mist patterns on flexural samples and crack growth from shrinkage holes and river patterns. The distribution of Al2O3 nanoparticles was found to improve the impact energy in both transverse and longitudinal directions by 111% (-28 kJ/m2) and 127% (32 kJ/m2), respectively. Crack deviation by the hard inclusions was found to be the mean mechanism of enhanced impact resistance.