Electrochemical reactions on some cemented metal carbides

✍ Scribed by Ashok K. Vijh; G. Belanger; R. Jacques

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 916 KB
• Volume: 6
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/0378-7753(81)80028-6

✦ Synopsis

The electrochemical behaviour of cobalt-cemented tungsten carbides has been examined in aqueous alkaline solutions. These electrodes exhibit a good surface stability in the potential region cu. 0.0 -0.7 V (us. RHE); the presence of a passivating surface oxide is indicated in this potential range. The anodic oxidation tendencies of a number of organic compounds were explored but only hydrazine underwent oxidation at an appreciable rate.

A detailed mechanistic study on the anodic oxidation of hydrazine has been carried out. The experimental data consist of potentiostatic and potentiodynamic current-potential relationships, reaction order derivatives, apparent heats of activation, and an ellipsometric investigation of the electrode surface. Based on these data and some general considerations, a mechanism is proposed in which the first charge transfer step involving a hydroxyl ion and the molecular residue of hydra&e is the rate-determining step (r.d.s.).