Comparison on the immersion corrosion and electrochemical corrosion resistance of WC–Al2O3 composites and WC–Co cemented carbide in NaCl solution |
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Authors: | Bin Han Weiwei Dong Bowen Fan Shigen Zhu |
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Affiliation: | College of Mechanical Engineering, Donghua University, Shanghai 201620 PR China.; Engineering Research Center of Advanced Textile Machinery of the Ministry of Education, Shanghai 201620 PR China |
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Abstract: | WC–15 wt% Al2O3 composites were prepared via hot pressing sintering technology. The corrosion behaviors of WC–Al2O3 composites and traditional WC–Co cemented carbide in NaCl solution were studied by immersion corrosion and electrochemical technique. The impedance value of the WC–Al2O3 composite increased more rapidly than WC–Co cemented carbide during the 24 hours, which indicated that WC–Al2O3 composites had a more compact passivation film than WC–Co cemented carbide. The results confirmed that the corrosion resistance of WC–Al2O3 composites was higher than that of WC–Co cemented carbide in NaCl solution. The corrosion mechanisms of WC–Al2O3 composites and WC–Co cemented carbide in NaCl solution were also revealed by SEM, EDS, XPS and Raman. The corrosion products of WC–Al2O3 composites mainly contain WO3, while for WC–Co cemented carbide they are Co(OH)2, Co3O4 and WO3. The different corrosion mechanism of the two materials is attributed to the Al2O3 phase instead of the Co binder, which avoids the galvanic corrosion between the WC phase and the Co binder.WC–Al2O3 composites possess higher corrosion resistance compared with WC–Co cemented carbide. The main corrosion mechanism for WC–Al2O3 composites is the oxidation of the WC phase. |
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