Abstract
In systems that contain hydrogen sulfide, corrosion products like iron sulfide are electron conducting and are often formed between neighboring electrodes of electrochemical probes and on the sensing element of electrical resistance (ER) probes. Such deposits make it difficult to measure the corrosion rate using the ER and electrochemical probes. Coupled multielectrode array sensors (CMAS) with coated finger-like electrodes have been used in aqueous systems containing H2S to avoid the effect of electron-conducting deposits. However, such a sensor cannot be used in a gas phase or in oil-water mixtures that contain sparsely distributed water particulates, because of the lack of contiguous electrolytes between the sensing surface of one fingered electrode and the sensing surface of another fingered electrode. This paper describes a CMAS probe with coated finger-like electrodes that have an additional outer coating. The additional outer coating is made of a solid electrolyte and forms an ion-conducting path from the sensing surfaces of one fingered electrode to the sensing surfaces of the other fingered electrodes. Experiments in humid air demonstrated that such CMAS probes performed well when the sensing surfaces of the individual electrodes were covered by corrosive electrolytes.
