Study On The Characteristics Of Solid-state Ag/AgX Reference Electrode Used In Deep Marine

Electrochemical parameters should be measured in cathodic protection systemfor marine steel structures. The reference electrode which has sensitive and excellentstability potential is one of the indispensable components of electrochemicalmeasurement. Due to the complexity of the marine environment, Ag/AgCl referenceelectrode, which is prepared by power press method, is regarded as the best referenceelectrode in electrochemical measurement nowadays. However, the Ag/AgClelectrode is not suitable for the cathodic protection system for the reason that itspotential lacks stability and high accuracy caused by the ions, such as Br and SOin seawater, and cannot be used in marine environment for a long time.In order to deal with the problems mentioned above, the Ag/AgX referenceelectrode is prepared by power press method in this paper. Firstly, we take out thesintering process, which can avoid the internal electrode pore that increases theinternal resistance caused by sintering. Secondly, XRD and SEM are used to evaluatethe AgX solid solution. Moreover, the Ag/AgX reference electrode has been fullyinvestigated in many aspects, such as long-term stability, Nernst responsecharacteristics and the influence of potential by seawater temperature, pH value,dissolved oxygen, flow rates in seawater, constant current polarization andbacteriostasis. The result shows that the potential difference of the Ag/AgX referenceelectrode is less than5mV within six months in natural seawater; in addition, it alsohas good Nernst response property of Cl when ranges from0.001mol/L to1mol/L because the E and lg linear fitting correlation coefficient is0.9996and0.9994while the intercept is0.2254V and0.2371V, which is consistent to theliterature; a relatively low temperature factor of near0.3mV/℃; meanwhile,dissolved oxygen, pressure and flow rate of seawater almost has no impact on the potential of Ag/AgX reference electrode besides good results inhibits SRB; when thepolarization current density achieve±10μA/cm2, the value of polarization within±5mV, which based on the government standard GB/T7387-1999. All the resultsmentioned above indicate that the solid-state Ag/AgX reference electrode is an idealreference electrode used for the potential monitoring or inspection in cathodicprotection engineering in the marine environment.Additionally, based on LabVIEW, a data acquisition system which is suitable formonitoring cathodic protection system in marine environment has been developed:The system of data acquisition and monitoring in cathodic protection. The systemcontains data acquisition and data processing functions, which can be realized by thedata acquisition and monitoring system in cathodic protection (referred to asAcquisition system) and the data recording and filing system (referred to as filingsystem) respectively.In Acquisition system, real-time monitoring potential (unit: mV, accuracy:0.1mV) can be realized by32channels parallel at any time interval. Potential isrepresented by figure, colors of indicator light and oscillogram, respectively. Theindicator light shows certain color when the value of potential is in certain interval,corresponding with certain actual protection status. Sound alarm starts when overprotection occurs on the current monitoring point and the data can be auto-savedduring the program processing.Filing system is mainly aiming at the measurement that require shorter timeinterval and longer duration in sampling, so that the size of data record files can beadjusted and the space of hard disk without changing the original data can be saved.