JP2001226788A - Electrode device for electric corrosion protection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode device with the decreased number of component parts for electric corrosion protection with the function hardly deteriorated even when used for a long period. SOLUTION: An electrode rod 3 having a male screw 7 and a electric- insulating holder 5 having a female thread 13 are included. The electrode rod 3 is screw-joined to the holder 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode device for electrical corrosion protection.

[0002]

2. Description of the Related Art Water storage tanks used for electric water heaters and elevated water tanks that use nighttime electric power are made of metal such as iron or aluminum. To prevent corrosion, the surfaces of the tanks are painted or enameled. Processing has been applied.

However, if a pinhole is generated in a part of the surface treatment and the metal is exposed, a local battery is generated there, and the metal becomes ions, and the electrolyte stored in the tank, for example, Dissolves in water. For this reason, the metal wall constituting the container rusts from the pinhole portion, and a hole is formed in the container.

[0004] The electrode device for cathodic protection is used as means for preventing such a phenomenon. Specifically, the electrode device for electrolytic protection is attached to the tank, the tip of the electrode is immersed in water in the tank, and the electrode side is used as the anode,
A potential difference is applied with the tank side as the cathode. Such an electrode device for cathodic protection is disclosed in, for example, Japanese Utility Model Laid-Open No. 55-75661.

[0005] However, the conventional electrode apparatus for corrosion protection has a problem that the structure is complicated, the number of components is large, and the cost of parts and assembly is high.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrode device for electrolytic corrosion protection that has a small deterioration in function even after long-term use.

[0007] Another object of the present invention is to provide an electrode device for electric corrosion prevention which has a small number of components and is economical.

[0008]

In order to solve the above-mentioned problems, an electrode apparatus for preventing corrosion according to the present invention includes an electrode rod and a holder. The electrode bar includes a fixed end at one end. The fixed end has an external thread formed on the surface. The holder has electrical insulation properties and includes a holding hole. The holding hole has an internal thread formed on the inner surface.
The electrode rod and the holding body, with a male screw provided at the fixed end and a female screw formed on the inner surface of the holding hole,
Screwed together.

As described above, one end of the electrode rod is screwed to the holding member having electrical insulation. Therefore, when the electrode device for preventing corrosion is mounted on the tank of the electric water heater, if the holding member is mounted on the tank. Good. The electrodes can be mounted without direct contact with the tank. The other end of the electrode rod is immersed in water stored in an electric water heater, and a voltage is applied between the electrode rod and the tank. This provides a corrosion-resistant effect on the tank.

The electrode rod and the holder are screwed to each other by a male screw provided on the fixed end and a female screw formed on the inner surface of the holding hole, so that the electrode rod and the holder are immersed in water stored in an electric water heater. The water that has traveled down the electrode rod must travel down the tiny gaps along the threads and valleys. For this reason, an electrode device for electric corrosion prevention having high water blocking performance can be obtained. By this water blocking, corrosion of the core wire connected to the electrode rod and disconnection due to the corrosion can be avoided.

In addition, the electrode apparatus for corrosion protection according to the present invention includes only two parts, ie, an electrode rod and a holder.
The number of parts and the number of assembly steps are reduced, and the cost is reduced.

[0012] Preferably, in the screw connection between the electrode rod and the holder, the contact surfaces thereof and the minute gaps along the screw valleys are filled with an adhesive filler.
In this case, a higher water shielding effect can be obtained.

[0013]

FIG. 1 is a partial sectional view of an electrode apparatus for corrosion protection according to the present invention. The illustrated electrode device for corrosion protection includes an electrode rod 3 and a holder 5. The electrode rod 3
It is conductive, rod-shaped, and has an external thread 7 cut over its entire length. One end of the electrode rod is joined to the holder 5 as a fixed end. The other end of the electrode rod 3 is immersed in water stored in an electric water heater or the like as an immersion end.

The holder 5 has an electrical insulating property. Further, the holding body 5 has a hollow holding hole 15 at one end side, and a female screw 13 is cut on an inner peripheral surface of the holding hole 15. At the other end, a hollow wire insertion portion 17 is provided. Further, an externally threaded mounting portion 19 is provided on the outer surface, so that the electrode apparatus for corrosion protection can be screw-mounted to a container such as an electric water heater.

The connection between the electrode rod 3 and the holder 5 is based on the fact that the portion of the male screw 7 cut at the fixed end is screwed to the female screw 13 of the holding hole 15. By the screw connection, the electrode rod 3 and the holder 5 are firmly connected.

As the electrode rod 3, a sintered ferrite having a spinel crystal structure represented by the chemical formula MO.Fe ₂ O ₃ can be used. MO uses a metal oxide containing nickel and zinc as main components. This sintered ferrite is a very suitable material because it hardly dissolves and loses weight when used as an electrode, and does not form an insulating film on the surface. The MO may be a divalent metal oxide such as manganese, cobalt, and magnesium. The composition ratio of iron oxide Fe ₂ O ₃ and metal oxide MO is such that iron oxide is 53 to 95 mol% in terms of Fe ₂ O ₃ and metal oxide is MO.
It is 47 to 5 mol% in conversion.

An example of a method for manufacturing the electrode rod 3 is as follows.
55 to 75 mol% of iron oxide and 45 to 25 mol% of a metal oxide such as nickel oxide or zinc oxide are sufficiently mixed in a ball mill, and then heated at 800 to 1400 ° C. under normal pressure for 1 to 3 hours, and cooled. And pulverized to a fine powder. Raw material for forming a fine powder, Fe instead of ₂ O _3, mixtures or Fe and Fe ₂ O _3, which corresponds to 55 to 75 mol% in terms of Fe ₂ O _3, these and Fe ₂ O ₃ Can be used.
Further, instead of the metal oxide, a compound which can be changed to these oxides by heating, for example, a carbonate, a hydroxide, an oxalate, or the like can be used.

In order to manufacture the electrode rod 3 from ferrite fine powder, the electrode rod 3 is formed into a predetermined shape by compression molding, extrusion molding, injection molding, cast molding, or the like, and a firing temperature of 1100 to 140 is used.
It is obtained by firing at 0 ° C. for 2 to 12 hours and then cooling.

The external thread 7 can be formed at the time of molding, or may be formed by grinding in post-processing.

Further, the electrode rod 3 may be formed of an alloy containing titanium and coated with a coating material containing a platinum group on the surface, instead of the sintered ferrite described above. A valve metal such as tantalum, zirconium, or niobium may be included in addition to titanium. Or 2
You may shape | mold with the alloy containing two or more types of valve metals.
As the coating material, not only the platinum group but also a material containing at least one kind of the platinum group and its oxide can be used.

As the holder 5, engineering plastics can be used. Among them, polyphenylene sulfide (PPS) is excellent in electrical insulation, heat resistance and water resistance, has a low coefficient of thermal expansion, is excellent in mechanical strength, and holds a metal electrode rod 3 used in warm water. It is most suitable as the holding member 5 which performs.

In addition to polyphenylene sulfide (PPS), for example, engineering plastics having electrical insulation such as polyamide / polyacetal may be used. Further, a synthetic rubber may be used. In order to manufacture the holding body 5, the holding body 5 is formed into a predetermined shape by compression molding, injection molding, casting, or the like.

FIG. 2 is a partial sectional view showing an example of wiring connection of the electrode apparatus for corrosion protection. In the case of wiring to the electrode device for electrical corrosion protection, as shown in the figure, it was inserted into the upper end surface 37 of the electrode rod 3 screwed to the holding hole 15 of the holder 5 and the wire insertion part 17 of the holder 5. The distal end of the core portion 33 of the insulated wire 31 can be brought into contact with the wire and solidified with the conductive adhesive 39 to be connected. The mounting portion 19 to be mounted on a container such as an electric water heater is installed on the side opposite to the side where the electrode rod 3 is mounted.

FIG. 3 is a partial sectional view showing another example of the wiring connection of the electrode apparatus for corrosion protection. The same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals. In this example, one end of the connection terminal 41 is fixed to the tip of the core portion 33 of the insulated wire 31 with solder 43, and the other end is connected to the upper end surface 37 of the fixed end 9 of the electrode rod 3. The connection terminal 41 has a spring property, so that the connection terminal 41 can be reliably brought into electrical and mechanical contact with the upper end surface 3 of the electrode rod 3. The mounting portion 19 is provided on the side where the electrode rod 3 is mounted.

FIG. 4 is a view showing a use example in which the electrode apparatus for electrolytic protection according to the present invention is used in an electric water heater. The electrode device 1 for electric corrosion protection is provided with an electric water heater 4 at the mounting portion 19 of the holder 5.
Is attached to the upper lid 45 of the tank 40. The tip of the electrode rod 3 is immersed in water 46. Reference numeral 49 denotes a heating element, 55 denotes an AC power supply, and 51 denotes an inflow / outflow hole of the water 46.

Then, the tank 40 of the electric water heater 4 is connected to the DC power supply 53 with the tank 40 on the cathode side and the electrode rod 3 on the anode side. As a result, the water 46 side is set to a high potential and the tank 4
The zero side is kept at a low potential, so that metal components constituting the tank 40 can be prevented from flowing out as positive ions, and rust can be prevented from being generated. The potential difference is theoretically 1.2
All you need is more than a bolt. Usually, the voltage is set to 24 volts.

In addition, the electrode device 1 for corrosion protection according to the present invention, as described with reference to FIGS.
And the holder 5, and the electrode rod 3 and the holder 5 are
Since the male screw 7 provided on the electrode rod 3 and the female screw 13 formed on the inner surface of the holding hole 15 are screw-coupled to each other, water transmitted through the electrode rod 3 reaches the valleys of the screws 7 and 13. It has to travel around very small gaps along the way. For this reason, the electrode device 1 for electrical corrosion protection having high water-blocking performance can be obtained. Due to this water blocking, the electrode rod 3
Corrosion of the core wire 33 (see FIGS. 2 and 3) connected to the wire and disconnection associated therewith can be avoided.

Further, the electrode apparatus 1 for anticorrosion according to the present invention.
In the above, there are only two main components: the electrode rod 3 and the holder 5. For this reason, the number of parts is extremely reduced, and the cost of parts and the cost of assembly are reduced.

It is desirable that the gap between the parts where the male screw 7 cut into the electrode rod 3 and the female screw 13 of the holder 5 are screwed to each other be filled with an adhesive filler. According to such a configuration, the water shielding property is further improved.

Further, in the embodiment shown in FIGS. 1 to 3, a male screw 7 is provided over the entire length of the electrode rod 3. According to this structure, electric field concentration does not occur in the portion of the electrode rod 3 that enters the water 46, and the electric field is dispersed, so that wear of the electrode rod 3 is reduced. Next, this point will be described with reference to experimental data.

FIG. 5 is a view showing a method of measuring a current value of an electrode device for electrolytic corrosion prevention having an external thread 7 over the entire length of the electrode rod 3.
The electrode apparatus for electrolytic protection used in the experiment is the same as that shown in FIGS.

FIG. 6 is a diagram showing a method for measuring a current value of an electrode device for corrosion protection as a comparative example. The electrode apparatus for corrosion protection used in the experiment is the same as that shown in FIGS. 1 to 3 except that the part of the electrode rod 3 that enters the water is a smooth surface.

5 and 6, an electrolytic solution 93 such as water is put in a container 91. Inside the electrolytic solution 93,
An electrode plate 92 is provided, and the electrode plate 92, the ammeter A, the DC power supply E, and the core wire 33 of the electrode device for anticorrosion are connected in series. In the experiment, measurement points a, b, c, and d were set on the electrode rod 3 of the electrode apparatus for cathodic protection, and each measurement point a
To d almost coincide with the liquid level of the electrolytic solution 93, and the current values at that time were measured and plotted.

FIG. 7 is a graph of the current value measurement result according to FIG. 5, and FIG. 8 is a graph of the current value measurement result according to FIG.
7 and 8, the vertical axis represents the current value, and the horizontal axis represents the measurement positions a to d of the electrode rod 3.

Referring to FIG. 7, in the case of an electrode device for corrosion protection having a male screw 7 over the entire length of the electrode rod 3, the current value is
It is almost constant regardless of the difference in the measurement positions (ad). This is because, in the case of the electrode rod 3 having the male screw 7 over its entire length, the male screw 7 is densely continuous in the axial length of the electrode rod 3, so that the current distribution is averaged in the axial length of the electrode rod 3. It is presumed that it has been converted. By averaging the current distribution, the wear of the electrode bar 3 is averaged in its axial length, so that the service life is extended.

On the other hand, in the electrode apparatus for cathodic protection shown in FIG. 6, as shown in FIG. 8, an extreme current concentration occurs at the tip a of the electrode rod 3. This is because only the tip of the electrode rod 3 has an acute angle portion. For this reason, in the electrode apparatus for cathodic protection shown in FIG.

Further, on the surface of the immersion end of the electrode rod 3,
When used for a long time, minerals contained in water precipitate as scale and scale. If the scale adheres, the energization efficiency deteriorates. Deterioration of energization efficiency due to scale adhesion
A difference occurs depending on the surface shape of the immersion end of the electrode rod 3.

Table 1 is a table showing the change with time of the measured passing current. In Table 1, the screw type is the electrode rod 3
The electrode device for corrosion protection has a male screw 7 over the entire length of the electrode. The smooth type is the electrode device for corrosion protection in which the surface of the electrode rod 3 is smooth. In the experiment, the measurement system of FIGS. 5 and 6 was configured, and almost the entire electrode rod 3 of the electrode device for cathodic protection was put in the electrolytic solution 93. The electrolytic solution used was one obtained by adding calcium lactate to standard water at 3%. As the power source E, the output voltage DC3
A 0 volt DC power supply was used. The experiment was performed for 10 days.

Referring to Table 1, the smooth type was 1 mA on the first day, but 0.2 mm on the 10th day.
5 mA and the current efficiency is reduced by as much as 50 percent.

On the other hand, for the screw type, 1.
At 2 mA, at day 10 it is 0.9 mA, and at day 10 the efficiency drops by 25 percent. That is, the one having the male screw 7 is more advantageous than the one having the smooth surface when used for a long period of time.

FIG. 9 is a front view showing another example of the electrode rod used in the electrode apparatus for corrosion protection according to the present invention. The illustrated electrode rod 3 has a structure in which a fixed end is a male screw 71 and an immersion end is a ring-shaped projection 72 provided at intervals. When the electrode rod according to this structure is used,
And the effect of improving current efficiency is obtained.

[0042]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide an electrode device for electrical corrosion protection with less deterioration in function even after long-term use. (B) It is possible to provide an economical electrode device for electric corrosion protection with a small number of components.

[Brief description of the drawings]

FIG. 1 is a partial front sectional view of an electrode apparatus for corrosion protection according to the present invention.

FIG. 2 is a partial cross-sectional view showing an example of wiring connection of the electrode device for corrosion protection according to the present invention.

FIG. 3 is a partial cross-sectional view showing another example of the wiring connection of the electrode device for corrosion protection according to the present invention.

FIG. 4 is a view showing a use example in which the electrode device for corrosion protection according to the present invention is used for an electric water heater.

FIG. 5 is a diagram showing a method for measuring a current value of an electrode device for electrolytic corrosion prevention having a male thread over the entire length of an electrode rod.

FIG. 6 is a diagram showing a method of measuring a current value of an electrode device for corrosion protection as a comparative example.

FIG. 7 is a graph of a current value measurement result according to FIG. 5;

FIG. 8 is a graph of a current value measurement result according to FIG. 6;

FIG. 9 is a front view showing another example of the electrode rod used in the electrode apparatus for cathodic protection according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode protection electrode device 3 Electrode rod 5 Holder 7 Male screw 13 Female screw 15 Holding hole

Claims (9)

[Claims] 1. An electrode device for electrolytic corrosion prevention including an electrode rod and a holder, wherein the electrode rod has a fixed end at one end, and the fixed end has a male screw formed on a surface thereof, The holding body has an electrical insulation property, includes a holding hole at one end, the holding hole is formed with a female screw on an inner surface, and the electrode rod and the holding body are the male screw of the fixed end and the male screw. An electrode device for corrosion protection, which is screwed to each other at the female screw portion of the holding hole. 2. The electrode apparatus according to claim 1, further comprising a filler, wherein the filler is filled in the fixed end portion and the screw connection portion of the holding hole. Electrode device for corrosion protection. 3. The electrode device for corrosion protection according to claim 1, wherein the electrode rod further includes an immersion end, and the immersion end has an uneven surface. An electrode device for electrical corrosion protection having a shape. 4. The electrode device according to claim 3, wherein the uneven shape is a male screw formed continuously from the fixed end to the male screw. 5. The electrode device according to claim 1, wherein the electrode rod includes a metal oxide as a main material. 6. The electrode device for electrical corrosion protection according to claim 1, wherein the main material of the electrode rod is a ferrite sintered body. 7. The electrode device for electrical corrosion protection according to claim 1, wherein said electrode rod is selected from a main material selected from valve metals such as titanium, tantalum, zirconium, and niobium. An electrode device for electrolytic corrosion prevention, which has been subjected to a surface treatment including at least one selected from the group consisting of platinum group metals and oxides thereof. 8. The electrode device for electrical corrosion protection according to claim 1, wherein the holder is made of a synthetic resin as a main component. 9. The electrode device according to claim 1, wherein the main body of the holding member is polyphenylene sulfide.