Aluminum and Nickel Alloy Multielectrode Sensors for Corrosion Monitoring at High Temperatures

Existing coupled multielectrode array sensors (CMAS) with epoxy insulations are promising devices for application as an online tool for corrosion monitoring. However, most of these devices have an upper operating temperature limit of approximately 70 °C.  At temperature above 70 °C, crevice formation between the electrode and the mounting epoxy may result in inaccurate high corrosion rates. In this paper, corrosion monitoring using coated aluminum and nickel alloy Inconel 600 electrodes at temperatures above 100 °C is presented. A diamond-like carbon thin film was deposited on the sensing electrodes. The effectiveness of the diamond-like carbon film in protecting the aluminum and Inconel 600 electrodes in corrosive solutions with pH range from 2.5 to 10 at 130-150 °C were demonstrated. The effective corrosion monitoring capability of the new electrochemical sensors at high temperatures was attributed to the high electrical impedance, and high corrosion-resistance properties of the diamond-like carbon film that prevented crevice formation between the aluminum and Inconel 600 electrodes.