Physicochemical and Mechanical Studies of Al2O3-Cu Metal-Ceramic Composites Obtained by Spark Plasma Sintering

Alumina-based composites have good properties such as high hardness, high chemical and temperature stability and excellent wear resistance. The type and amount of additive as well as the heat treatment profile has a significant effect on the physical properties and chemical behavior of the composite produced. In this work, Al2O3-based cermet composites with various concentration of copper (5, 15, and 25 wt %) were sintered by spark plasma sintering (SPS) at 1350 degrees C and 30 MPa. The phase composition and morphology of Al2O3-Cu composites were investigated by powder X-ray diffraction, SEM, and EDX techniques. Similar phases (Cu, Al2O3, CuAlO2 and Cu2O) were identified in all samples. However, differences in microstructure were observed in the microscopic study. The effect of copper concentration on the physical properties (microstructure, Vickers hardness, density, fracture toughness, electrical resistance) has been investigated. In comparison, low electrical resistance 0.005 ohm m and high fractural toughness 5.41 MPa m(1/2) were obtained for the composite with 25 wt % of copper. Moreover, the sintering kinetics of alumina-copper cermet was studied in different temperatures. The dominant mechanism was determined for Al2O3-25%Cu by linear shrinkage data. The volume diffusion and grain boundary diffusion of the main mechanism were determined and the activation energy (Q) for Al2O3-25%Cu spark plasma sintering process was obtained 329.05 kJ mol(-1) which was less than the ones reported for pure alumina sintering.