Corrosion Behavior of WC-Co-(Ni)-(Cr) Cemented Carbide in Neutral Solution

Three groups of WC-Co-(Ni)-(Cr) cemented carbides with different binder phase compositions were prepared by powder metallurgy using WC, Co, Ni and Cr3C2 powders as raw materials. The corrosion behavior of the three alloys in neutral solution was studied by polarization curve test and immersion experiment. The corrosion mechanism was discussed by means of scanning electron microscopy, energy spectrum analysis, X-ray photoelectron spectroscopy (XPS) and EBSD. The results show that in neutral solution the corrosion of WC-Co and WC-Co-Cr cemented carbides is mainly caused by the selective dissolution of Co and the corrosion products after immersion are mainly composed of Co(OH)2. The corrosion resistance of WC-Co cemented carbide in neutral solution can be improved by the addition of Cr, which may be related to the decrease in the content of hcp-Co in the binder phase by adding Cr. Adding Ni and Cr together can further improve the corrosion resistance of WC-Co cemented carbide in neutral solution. After immersion for 480 h in Na2SO4 solution, the WC-Co-Ni-Cr alloy sample is just corroded slightly