Effect of sintering temperatures on the properties of in-situ copper-niobium-titanium di-boride composites

Abstract

This work investigated the effect of the sintering temperatures on the densification of the powders, density, relative density, microhardness, coefficient of thermal expansion, and corrosion resistance in sulphuric acid solution environment of copper-niobium-titanium di-boride composite. A 90% weight of copper, reinforced with a 6% weight of niobium micro-particles and 4% weight of titanium-diboride was prepared in powdered form and sintered in two different temperatures of 650 °C and 700 °C using the spark plasma sintering method. The crystal phases and the morphologies of both the starting powders and the sintered samples were analyzed by the use of X-ray diffraction with copper Alpha-K radiation and scanning electron microscopy with energy dispersive X-ray spectroscopy. The results show that sintering at a temperature of 700 °C reduced the displacement rate of the powders with a higher microhardness value of 941 MPa when compared with the sintering temperature of 650 °C, which prolonged the displacement rate of the powders with a lower microhardness value of 827 MPa. The sintered samples recorded negative thermal expansion values of − 1.375 × 10 −5 °C −1 and − 7.780 × 10 −6 °C −1 at temperatures of 650 °C and 700 °C, respectively. The sample sintered at 700 °C has better micro-hardness and better corrosion resistance in a sulphuric acid environment when compared to the one sintered at 650 °C. This study has shown that the varying of the sintering temperatures has an effect on the properties of the composite under study. The produced composites can be used to control the mechanical and electrical properties, and the thermal expansion of functional materials, such as superconductors, semiconductors, ferroelectrics, magnetic and Mott insulators, etc. Keywords Copper-metal matrix composites spark plasma sintering • Microstructure • Negative thermal expansion • Corrosion in sulphuric acid * Azunna Agwo Eze,