KR970001327Y1 - Electro-chemical pitting measuring method - Google Patents

Abstract

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Description

Atmospheric Corrosion Measuring Device by Electrochemical Method

1 is an explanatory diagram showing a configuration of an atmospheric corrosion measuring apparatus in a conventional atmospheric environment.

2 is an explanatory diagram showing the configuration of the atmospheric corrosion measurement apparatus by the electrochemical method according to the present invention.

3 is a chart for the change of galvanic current and electrode current according to chlorine ion concentration during solution precipitation / transition process.

* Explanation of symbols for main parts of the drawings

1: dry oven 2: solution dipping vessel

3: metering valve 4: absorbent cotton fabric

5: measuring specimen 6: galvanic specimen

7 reference electrode 8 ammeter

9: voltmeter 10: recorder

11: polyethylene resin

The present invention relates to a device for measuring the corrosion rate using an electrochemical method in an air environment in which drying (DRY) and wetting (WET) are repeated. More specifically, the measuring principle and The present invention relates to a device for quickly and easily measuring the cause of atmospheric corrosion and the rate of atmospheric corrosion due to the simple analysis method.

In general, destructive damage to devices and structures caused by corrosion occurs most extensively in the atmosphere.

The losses due to atmospheric corrosion include not only the direct loss of metal structures exposed to the atmosphere, but also the cost of repairing paints and coating antirust coatings.

Atmospheric corrosion is a corrosion phenomenon occurring in a thin electrolyte layer formed by adsorption of water or air gases on a metal surface, and under actual atmospheric corrosion, the electrolyte layer has various thicknesses ranging from several molecular layers to several micrometers. Depending on the thickness of the electrolyte layer, atmospheric conditions can be classified into dry and wet conditions, and metals can be classified into these dry and wet conditions in the atmosphere, and under the atmosphere, the metal is placed in a state of repeating such dry and wet conditions. Recently, as the pollution problem becomes serious, attention is being focused on the study of the atmospheric corrosion characteristics of metal materials.

In addition, as the demand for highly anti-rust metal materials or surface treatment products increases, there is a demand for an atmospheric corrosion measuring apparatus capable of quickly and easily identifying atmospheric corrosion characteristics.

On the other hand, in the prior art, the atmospheric corrosion measuring apparatus uses a zero resistance ammeter as a current flowing from the galvanic specimen 20 of the positive pole to the measurement specimen 21 of the negative pole, as shown in FIG. The measurement is carried out using the reference numeral 22 and the recording is carried out in the recorder 23.

In addition to the advantages of measuring the actual situation, the conventional atmospheric corrosion apparatus having the above-described structure has very complicated parameters of the atmospheric corrosion factor, so that the atmospheric corrosion mechanism is opaque and the period of change between day and night is 24 hours. There are difficulties in controlling artificial atmospheric corrosion factors such as pollutants, humidity / dry cycles and time variables.

In addition, referring to other examples in the prior art, a method for measuring weight loss, observing corrosion patterns, or the like after the atmospheric corrosion promoting test, which is performed by repeating SOLAR RADIATION and a wet state using a weathering machine. Methods of analyzing corrosion products are used.

As described above, it is possible to shorten the experiment period by repeating the artificial light irradiation and the wet state using the weather resistance tester, but the atmospheric corrosion state is not known during the transition process from the measurement equipment to the expensive and solution deposition and drying. There is a problem that is difficult to measure the change state of each pollutant and the like having a great influence.

The present invention was devised to solve the above problems, and two metals with different electrode potentials (GALVANIC COUPLING) formed a galvanic pair to react to chemical reactions due to corrosion when transitioning from solution deposition to drying. The purpose of the present invention is to provide a device capable of measuring the atmospheric corrosion of the more corrosive metal among the two metals by using the electrochemical measurement method of the galvanic current and the electrode potential generated.

In order to achieve the above object, the present invention provides a solution deposition container made of transparent acrylic inside a dry oven capable of drying the specimen and being able to dry the specimen well, and adjusting the amount of solution at the bottom of the solution deposition container. A metering valve is attached and a galvanic specimen having a higher corrosion resistance and a measurement specimen for determining atmospheric corrosion characteristics are provided inside the solution deposition container, and the galvanic specimen pair is insulated using an electrical insulator polyethylene resin. Surround the periphery of the polyethylene resin with an absorbent cotton fabric, connect the measurement specimen and the galvanic specimen with an electric wire through an ammeter, the ammeter is connected with a recorder and an electric wire, and the measurement specimen and the reference electrode are connected with an electric wire through an ammeter. The voltmeter is connected to the recorder By providing an atmospheric corrosion measurement device characterized in that connected to.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The configuration of the present invention is a temperature controllable as shown in Figure 2 can be dried arbitrarily the specimen and the dry oven (DRY OVEN) 1 is well visible inside, the inside of the dry oven (1) A solution immersion container 2 made of transparent acrylic is positioned, and a metering valve 3 for controlling the discharge of the solution 13 is attached to the bottom of the solution immersion container 2.

In addition, the solution deposition vessel (2) is provided with a measuring specimen (5) having a (-) electrode to know the corrosion characteristics and a galvanic specimen (6) having a (+) electrode is provided between the galvanic specimen pair It is insulated using polyethylene resin 11, which is an insulator, is surrounded by absorbent cotton fabric 4 around the polyethylene resin 11, and the measurement specimen 5 and the galvanic specimen 6 to a minute galvanic current amount. It is connected by wire through a measurable ammeter 8 which is connected to the recorder 10 which records information of the measured corrosion state.

Meanwhile, a reference electrode 7 is provided inside the solution deposition container 2, and the reference electrode 7 is a measurement specimen 5 through a voltmeter 9 for measuring an electrode potential. ) And the voltmeter 9 is configured to be connected to the recorder 10 for recording the electrode potential by a wire.

Hereinafter, the operation and effects of the present invention will be described.

As shown in FIG. 2, the solution deposition container (2) made of transparent acrylic is placed inside the dry oven (1) which can be easily seen inside and the temperature control is possible to dry the specimen, and the solution deposition container (2). The lower part of the) is attached to the metering valve (3) that can accurately control the discharge amount of the solution to discharge the solution (13).

As the solution 13 is discharged, an absorbent cotton fabric 4 which absorbs the solution well is attached around the two galvanic specimen pairs 5 and 6 so that the thickness of the electrolyte 5a layer on the specimen surface decreases at a constant rate. In addition, the pair of specimens (5, 6) is composed of a measuring specimen (5) to know the large-type characteristics and galvanic specimen (6) having a higher corrosion resistance and having a positive electrode during the solution deposition / drying transition process. The galvanic current flowing from the galvanic specimen to the side specimen with the negative electrode is measured by an ammeter 8 capable of measuring a small amount of current less than 10 mA and recorded in the recorder 10.

In addition, the electrode potential of the measurement specimen 5 at the thickness of the very thin electrolyte 5a of the measurement specimen 5 was measured using a voltmeter 9 by a reference electrode 7 and recorded in the recorder 10. do. At this time, the shape of the reference electrode (7) is to be slightly bent toward the measurement specimen (5) in order to reduce the error of the chemical reaction as possible to obtain an accurate voltage measurement value.

On the other hand, the arrangement state of the two galvanic specimens is thinly separated by 1 mm between the galvanic specimen pairs (5,6), and electrically separated using a non-conductive polyethylene resin (11), and then installed on the plane (12), Adjacent parts of the polyethylene resin 11 were attached to the double-sided tape with an absorbent cotton fabric 4 of about 200 탆 thick, which was able to absorb the solution well at a constant rate, at both electrodes exposed to the corrosion atmosphere during the solution deposition / drying transition process. By accurately measuring the galvanic current flowing, it was possible to predict the atmospheric corrosion rate of the measurement specimen (5).

At this time, the aqueous solution used for the solution deposition was compared with the distilled water free of impurities and the solution containing a specific impurity was able to obtain the effect of contaminants affecting the atmospheric corrosion characteristics.

As described above, the present invention can describe the tendency of atmospheric corrosion according to changes in humidity and pollutants in the air during the day and night as in actual conditions, and thus can be usefully used for evaluating the corrosiveness in the atmospheric environment.

As described above, the effects of the present invention will be described in detail with reference to FIG. 3 through the present invention.

Low carbon steels were measured with galvanic specimens with (-) electrodes and Cu plates with galvanic specimens with (+) electrodes to show the change in galvanic current with chlorine ion concentration during solution deposition / transition process.

The increase of galvanic current during drying was not observed in distilled water. However, when chlorine ions are present, the higher the concentration of chlorine ions, the more the galvanic current flows and lasts longer.

In addition, it can be seen that the atmospheric corrosion is most affected by the solution deposition / dry transition from the rapid increase of the galvanic current during the transition from solution deposition to drying.

The electrode potential of the low carbon steel with respect to the saturated calomel reference electrode in the 0.5M NaCl solution was investigated. The electrode potential increased slowly compared to distilled water.

This shape means that the corrosion rate is reduced by rapidly forming a stable passivation film of iron when using distilled water.

However, the increase in galvanic current when containing chlorine ions can be presumed to be a chemical reaction in which the anodic corrosion reaction is accelerated by the breakdown of the passivation film by chlorine ions as the thickness of the electrolyte 5a layer becomes thin. The effect of chlorine ion on the atmospheric corrosion characteristics of iron can be easily and quickly compared to the measurement method using outdoor exposure test or weather resistance tester.

Here, the unexplained arrows in FIG. 2 and FIG. 3 indicate when the solution starts discharging.

In addition, it is possible to obtain continuous information according to the change of corrosion atmosphere, so much more information can be obtained than the method of weight loss or increase.

In other words, it can be used to evaluate the corrosiveness of the atmosphere because it can reproduce the day and night humidity changes in the atmosphere and the corrosion tendency due to pollutants.

As described above, the present invention relates to a device for measuring corrosion characteristics using an electrochemical method in an air environment in which drying (DRY) and wetting (WET) are repeated according to the present invention. And since the analysis method is simple, various corrosion factors affecting the atmospheric corrosion characteristics can be promptly ordered, which can contribute to increasing the industrial use effect.

Claims (1)

A solution dilution vessel (2) made of transparent acrylic is placed inside the dry oven (1), which is easily visible and allows the specimen to be dried, and the temperature is controlled. The solution (13) is disposed below the solution distillation vessel (2). A metering valve (3) for adjusting the amount is attached, and a measuring specimen (5) and a galvanic specimen (6) having higher corrosion resistance are provided inside the solution deposition vessel (2) to measure the atmospheric corrosion characteristics. The pair of specimens 5 and 6 are insulated using polyethylene resin 11, which is an electrical insulator, and the periphery of the polyethylene resin 11 is surrounded by an absorbent cotton fabric 4, and the measurement specimen 5 And the galvanic specimen 6 by a wire through an ammeter 8, the ammeter 8 is connected to the recorder 10 by a wire, and the measurement specimen 5 and the reference electrode 7 is an ammeter 9 Is connected to the wire through the voltmeter 9 is the recorder Atmospheric corrosion measuring apparatus characterized in that connected to the wire (10).