Comparison on the immersion corrosion and electrochemical corrosion resistance of WC–Al(2)O(3) composites and WC–Co cemented carbide in NaCl solution

WC–15 wt% Al(2)O(3) composites were prepared via hot pressing sintering technology. The corrosion behaviors of WC–Al(2)O(3) composites and traditional WC–Co cemented carbide in NaCl solution were studied by immersion corrosion and electrochemical technique. The impedance value of the WC–Al(2)O(3) composite increased more rapidly than WC–Co cemented carbide during the 24 hours, which indicated that WC–Al(2)O(3) composites had a more compact passivation film than WC–Co cemented carbide. The results confirmed that the corrosion resistance of WC–Al(2)O(3) composites was higher than that of WC–Co cemented carbide in NaCl solution. The corrosion mechanisms of WC–Al(2)O(3) composites and WC–Co cemented carbide in NaCl solution were also revealed by SEM, EDS, XPS and Raman. The corrosion products of WC–Al(2)O(3) composites mainly contain WO(3), while for WC–Co cemented carbide they are Co(OH)(2), Co(3)O(4) and WO(3). The different corrosion mechanism of the two materials is attributed to the Al(2)O(3) phase instead of the Co binder, which avoids the galvanic corrosion between the WC phase and the Co binder.