Electrochemical corrosion behavior of hot-pressing sintered WC-Al2O3 composite in alkaline and acidic solutions

• Published in: Journal of materials science Vol. 56; no. 6; pp. 4120 - 4134
• Main Authors: Han, Bin, Zhu, Shigen, Dong, Weiwei, Bai, Yunfeng, Ding, Hao, Luo, Yilan, Di, Ping
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-02-2021; Springer Nature B.V
• Subjects: Aluminum oxide; Cemented carbides; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Cobalt; Corrosion mechanisms; Corrosion resistance; Cracks; Crystallography and Scattering Methods; Electrochemical corrosion; Electrode polarization; Grain boundaries; Materials Science; Morphology; Oxidation resistance; Polymer Sciences; Pressing; Solid Mechanics; Sulfuric acid; Tungsten carbide
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-020-05521-6

In this study, WC-Al
2
O
3
composite was fabricated by vacuum hot-pressing sintering. The corrosion behavior of WC-Al
2
O
3
composite in NaOH and H
2
SO
4
solutions was investigated by electrochemical measurements. The corrosion mechanisms were analyzed and revealed in light of corrosion morphology observation and composition characterization. The results confirmed that WC-Al
2
O
3
composite possessed higher corrosion resistance than WC-Co hard metal in H
2
SO
4
solution. Conversely, WC-Al
2
O
3
composite behaved similar corrosion resistance compared with WC-Co hard metal in NaOH solution. The key reason for higher corrosion resistance in H
2
SO
4
solution is the stable WO
3
passive film. The oxidation of WC phase leads to neck cracks along with grain boundaries, which is attributed to the preferential corrosion of grain boundary and the stress derived from the volume expansion during polarization and drying processes. In NaOH solution, the corrosion mechanism of WC-Al
2
O
3
composite mainly attributed to the dissolution of WC phase, but Al
2
O
3
phase is relatively stable.