Non-isothermal oxidation kinetics of WC–6Co cemented carbides in air

Abstract

The oxidation of WC–Co cemented carbides cutting tools is a key factor in determining tools' life during dry and high speed cutting. Thus, its investigation is of great importance to the design and development of cutting tool materials. In this paper, the non-isothermal oxidation of WC–6Co cemented carbides was carried out on simultaneous thermogravimetry-differential scanning calorimetry (TG-DSC) thermal analyzer (Netzsch STA 449C) between room temperature and 1273K at different heating rates (β=5, 10, 15 and 20K/min) in a dry air atmosphere under the atmospheric pressure. The results show that, with the heating rate increasing from 5K/min to 20K/min, the extrapolated initial temperature (Tei), the peak temperature (Tp), and the extrapolated final temperature (Tef) of the oxidation of WC–6Co cemented carbides increased from 957K to 997K, from 1014K to 1079K, and from 1030K to 1094K, respectively. The apparent activation energy (Ea) of the oxidation of WC–6Co cemented carbides was 206.85kJ/mol calculated by Flynn–Wall–Ozawa (FWO) method, and preexponential factor (A) was 5.02×109min−1. The oxidation experiment data of WC-6Co was in good agreement with R2 kinetic model. The reaction rate can be described by dα/dt=1010exp(−24,879/T)(1−α)1/2.