Design And Application Of Electrical Resisstance Probe For Natural Environment Corrosion Monitoringin

Through the study of the electrical resistance probe corrosion monitoring technology,this paper focuses on the importance of the role of the electrical resistance probe sensor in the process of corrosion monitoring.Through the in-depth study of the probe structure and the reference of the predecessors' work,a resistance probe is designed for the corrosion monitoring in natural environment.The improved design of the probe is mainly from two aspects.One is the geometric structure of the probe,and the other is the wiring structure of the measuring.An elevtrical resistance probe monitors corrosison by measuring the change in resistance of the metal as the corrosion progresses.The larger initial resistance of the probe,the lower requirement of the accurate of the probe measurement circuit,and the greater the ratio of the probe resistance to the total resistance of the resistance probe corrosion monitoring system.Therefore,during the design of the probe,a larger starting resistance is selected.In order to obtain a large starting resistance,the metal of the probe needs to have a small cross-section structure,that is,the metal needs to be very thin.In the form of tubular,filamentous,flaky and other forms of probe structure,ultra-thin sheet or metal film is most easily to be processed.Therefore,the metal of the probe is finally decided to be ultra-thin sheet.In the stage of probe design,three types of metal sheet were designed.After comparing and analyzing several kinds of common micro resistance measurement methods,probe resistance measurement method was finally determined as constant current manometry method.Because the measurement principle is simple,and the measurement accuracy is relatively high.The design principle of the wiring structure of the probe is to reduce the wiring resistance and improve the probe resistance measurement accuracy.The probe is designed with five wiring ports,which can be connected to the data acquisition interface of the resistance probe by drawing five wires on the back of the probe metal.The metal parts of the probe are mainly made of Q235 steel,which is commonly used in industry.Corrosion coupons for comparative experiments were made of me tal material which was taken from the same base metal as the probe.The substrate of the probe is made of acrylic board with good corrosion resistance and good mechanical properties.The epoxy resin with large temperature range is chosen as sealing materia l of the probe.Copper wire with a small resistivity is soldered to the probe metal by a soldering iron using tin-lead solder.A three-month comparative experiment of coupon weight loss and resistance probe corrosion monitoring was carried out in the laboratory.The corrosion products of the coupons and probes were analyzed by corrosion product morphology analysis.The monitoring results obtained by the probe are compared with the data obtained by the coupon method.The trend of the corrosion rate of the probe is the same as that obtained by the corrosion coupon method.The overall corrosion rate of the probe is larger than that of the coupon method.The ratio is about 1.95 to 2.99 times.Compared with the similar resistance probe test data in the market,the accuracy of the resistance probe test data designed and manufactured in this experiment is obviously improved,which makes it have better application value.