SU960638A1 - Polarization resistance meter - Google Patents

Description

one

The invention relates to electrical measuring equipment, and more specifically to devices measuring the physicochemical parameters of the metal-solution interface, and can be used to determine the rate of electrochemical corrosion of metals under the conditions of the presence on their surface of layers of corrosion products, deposits, scale, adsorbent films, etc. .

A device that permits measuring the polarization resistance of a metal in solution to determine the corrosion rate is known as an electrical measuring circuit to which the transducers are connected. Electrical circuits are made for direct or alternating current and have a galvanostatic or potentiostatic measuring principle. - With their help, the register is either offset of the potential of the corroding electrode for a given Tbk, or change

current at a given potential jump. The polarized resistance is calculated by the ratio of the magnitude of the potential displacement to the polarizing current, the latter being inversely proportional to the corrosion rate HZ

For corrosion systems with a large polarization capacitance, the transient time during measurement

fQ is quite large — about a few tens of minutes and accurate measurement of the polarization resistance is almost impossible.

The disadvantage of such meters

5 is the impossibility of using them to measure the polarization resistance and determine the corrosion rate of electrodes with a high polarization capacitance.

Claims (2)

20, the most; Close to the invention by purpose and technical nature is the P5035 corrosion rate meter. It includes a two-electrode measuring transducer in one of the arms of the bridge. The opposite shoulder contains measuring potentiometers. The moment of equilibrium is determined by the zero current in the indicator diagonal of the bridge TzJ. The disadvantage of the device is a large measurement time due to the long process of balancing. The aim of the invention is to increase the measurement speed. The goal is achieved by the fact that the polarization resistance meter contains a two-electrode converter in one of the four-arm comparison arm, the second comparison arm of which includes two series-connected resistors, the ratio shoulder resistors, a constant voltage source and an alternator connected through the switch to the supply diagonal of the bridge, to compensate for the initial EMF connected to the two-electrode converter, zero. indicator, an additional generation is introduced a constant voltage torus of adjustable amplitude and, ne. Secondary output: an output of an alternating voltage generator of adjustable amplitude is connected to one of the vertices of the power supply of the bridge, and the second output is connected to the corresponding leads of the second shoulder of the bridge comparison through a switch. FIG. 1 shows the principle of the polarization resistance meter; in fig. 2 - equivalent electrical circuit of the measuring converter. The polarization resistance meter contains a converter meter 1, connected in the bridge shoulder Z-3 in series with the resistor k, mode switch 5. The reference arm includes two reichords 7 and 8. The connection 9 of the reichords 7 and 8 through the switch 10 includes a generator. 11 DC voltage with adjustable amplitude. The bridge shoulders 2-12 and 6-12 include the resistors of ratios 13 and 14. A null indicator is connected to the bus 12 of the bridge 15. In the measuring arm 2-3, the I6xvi resistor 17 source DC voltage is used as a compensator for the initial EMF . The power supply diagonal of the bridge includes an alternator 18 and an alternating current voltage of 84 19. - In the equivalent circuit of the measuring converter tfig.2) resistance - solution 20 is connected in series with polarization resistance 21 and generator 22 of the initial EMF. The polarization capacitance 23 is connected in parallel with the polarization resistance and the initial emf generator. The measurement is carried out as follows. On alternating current by a reohord 8, the resistance of the solution 20 is compensated, and on a constant current / reohord 7, the initial emf of the generator 22 is compensated. After that, the supply voltage 19 of the direct current is included in the supply diagonal of the bridge 2-6, providing field measurement 21, as a result of the fact that the resistance of solution-20 is compensated, and the polarization resistance 21 is shunted by a polarization capacitance 23, the bridge turns out to be very unbalanced. To reduce the charging time of the polarization capacitor 23, a switch 10 is connected to the generator 11 of a variable-voltage direct current with an adjustable amplitude and its output voltage is chosen such that no current passes through the zero-indicator 15. After that, the key 10 is opened and the MOST is balanced by means of a reichord 7 "During the balancing time, the polarization capacitance 23 practically has no time to discharge, since this is prevented by the current flowing from the source of direct current voltage 19 included in the supply diagonal 2- 6 The operation of charging the capacitance 23 of the bridge is performed several times until the closing-opening of the key 10 ceases to affect the reading of the null indicator 15. Thus, the measurement time was reduced from 20 ... O min to 1..2 min with the accuracy of measurement of the order of 10, the range of application of the meter as compared with the known ones has expanded, and the ability to determine the corrosion rate of metals in the presence of various deposits, corrosion products, and scale has been found. Claims A polarization impedance meter comprising a two-electrode transducer in one of the four-arm comparison arms, the second comparison arm of which includes two series-connected single conductors, the ratio shoulder resistors, the source (DC voltage and alternating current generator connected through / supply bridge diagonal, initial ZDS compensator, connected to a two-electrode converter, a null indicator, characterized in that, with the aim of increasing 84 Measurement, an additional DC voltage generator of adjustable amplitude and a key are inserted, the first additional DC voltage generator of adjustable amplitude is connected to one of the power peaks of the bridge, and the second output is connected via a key to the corresponding pins second shoulder of the bridge comparison. Sources of information taken into account in the examination 1. US patent ff O tOSSI, class ZO t-ISS C, publ. 1977. 2.Antropov L.I. et al. Metal Protection, 1976, 12, 2.ZS. / t