The corrosion performance for ultrafine WC-12Co processed by heat treatments in different pH solutions

Abstract

The corrosion performance of WC-12Co after different post heat treatments (1100 °C, 1100 °C + 400 °C, 1100 °C + 500 °C, 1100 °C + 600 °C), were tested in 0.05 M H2SO4, 0.1 M Na2SO4, and 0.1 M NaOH. Heat treatments influence the corrosion performance of WC-12Co in acidic and neutral environments. However, the corrosion properties for WC-12CO in alkaline solutions are independent of the heat treatments. W and C diffuse to Co from the quenching process, dramatically improving corrosion resistance, with higher annealing temperature slightly reduces the corrosion performance. The rank of corrosion nucleation parameter tested by EIS and potentio-dynamic polarisation, with the corrosion expansion rate measured by potentio-static polarisation at +0.2 VSCE, + 0.5 VSCE, and + 0.8 VSCE for 30 min are not the same. The corrosion mechanism tested in different pH values is analysed using SEM, XPS, and DFT calculations.