The Effect of the Binder Phase and Sintering Temperature on the Properties of Spark Plasma Sintering WC-Co Cemented Carbides

Abstract

Cemented carbides belong to one of the most important groups of tool materials, whose percentage among all other materials used for cutting tools has reached about 50% in the global industry. Powder metallurgy methods have been used to produce cemented carbides, of which spark plasma sintering (SPS) is considered highly prospective. This paper presents the results of preliminary research concerning the effect of the fraction of the binder phase and sintering temperature on the microstructure, density, hardness and resistance to brittle fracture of cemented carbides produced by spark plasma sintering. The test materials were WC powder with a purity of min. 99.5% and Co powder with a purity of min. 99.8%. The obtained mixtures (WC-3Co, WC-6Co and WC-9Co) were sintered using the SPS method at 1300°C, 1350°C and 1400°C. The heating rate was 400°C/min. The pressing load was 80 MPa. Density measurements were carried out using the Archimedes method in accordance with PN-EN ISO 3369:2010, while hardness measurements, using the Vickers' method, were performed in accordance with PN-EN 23878:1996. Resistance to brittle fracture was determined based on the measurement of the length of cracks formed on the corners of the indentation. The observations of the microstructure and analysis of chemical composition were carried out using the scanning electron microscope. The phase composition of the obtained materials was determined by means of X-ray diffractometry.