HYBRID COMPOSITES REINFORCED WITH GRAPHENE AND TITANIUM CARBIDE IN AA7068 MATRIX: EVALUATION OF MECHANICAL AND TRIBOLOGICAL PROPERTY

Abstract

The present work deals with the fabrication of AA7068 as a matrix reinforced with different weight percentages of titanium carbide (0, 0.5, 1, 1.5, 2, and 2.5) % and with a constant weight percentage of graphene of 1 % using the stir casting method. The objective of this work is to study the mechanical and tribological properties of the hybrid composite. The uniform distribution of graphene and titanium carbide particles in the AA7068 matrix was validated with SEM investigations of the manufactured composite. A tensile test was performed, and a maximum ultimate tensile strength (UTS) of 199 MPa and a low percentage of elongation of 4.42 were obtained for the AA7068-1.0 w/% graphene-2.5 w/% TiC composite. The hardness of the composite was measured using a Rockwell hardness tester, and a maximum value of 63 HRB was obtained for the AA7068-1.0 w/% graphene-2.5 w/% TiC composite. The hardness increased as the percentage of TiC increased. The impact strength was determined with a Charpy test, and a maximum value of 4.5 J was obtained for the AA7068-1.0 w/% graphene-2.5 w/% TiC composite. A dry sliding wear test was performed in a pin-on-disc wear testing machine with different loads (5, 10 and 15) N, a constant sliding speed of 1000 min–1, and a sliding distance of 1000 m. The sample having 2.5 w/% TiC had a lower coefficient of friction and lower wear loss under different load conditions. Due to the presence of graphene and TiC reinforcements, the composites’ tensile, hardness and tribological properties improved significantly when compared to the aluminium alloy 7068 matrix.