INSTALLATION FOR ELECTROCHEMICAL SURVEY OF METAL CORROSION Russian patent published in 2014 - IPC G01N17/02 

FIELD: electricity.

SUBSTANCE: installation for electrochemical survey of metal corrosion (Fig. 1) includes a circuit measuring electrode potentials, a circuit measuring corrosion current and a temperature regulator. The circuit measuring electrode potentials consists of electrodes (1) submersed into solutions placed in containers (4). Solutions are coupled by a salt bridge (3). A comparison electrode (e.g., silver-chloride electrode) (2) is submerged into the solution. The switch (6) and millivoltmeter (7) allow measuring potentials of metal electrodes in regard to the comparison electrode. The circuit measuring corrosion current consists of electrodes (1) submersed into solutions placed in containers (4). Solutions are coupled by a salt bridge (3). The following equipment is coupled in series between electrodes: a toggle switch (5), a calibrating resistor (8) with high-ohmic digital millivoltmeter (9) connected to it in parallel, a resistor box (10). The temperature regulator consists of a container filled with heat medium, for example water (13), with submerged vessels with surveyed electrodes as well as a stirrer (11) and thermometer (12). Electrochemical survey of the corrosion cell is made in the following way. The installation is assembled in compliance with the diagram (Fig. 1). Metal samples are isolated partially along its length by heat shrink tube or lacquer in order to create the unite area surface and to prevent contact of metal surface with solution-air phase boundary. Then the surface is treated in compliance with GOST 9.305-84. At the open toggle switch (5) potentials of the surveyed metal samples are measured when current is unavailable in the circuit (stationary potential of the metal electrode), which is countered in regard to standard hydrogen electrode (SHE). At closure of the circuit by the toggle switch (5) the required value of electric resistance is set by the resistance box (10) and voltage drop is measured at the calibrating resistor (8) by millivoltmeter (9). The obtained voltage value is used for calculation of current intensity in the in the surveyed circuit as per Ohm's law. According to obtained experimental data corrosion diagram is plotted in coordinates E(SHE)=f(I). In Fig. 2 there is an example of such diagram. Then calculation is made for degree of anode, cathode and ohmic control as well as for weight index of corrosion.

EFFECT: simplifying installation diagram to measure current intensity of practically short-circuited corrosion cell.

2 dwg