JPH06147792A - Corrosion inhibiting container and radiator corrosion inhibiting method - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent internal corrosion of aluminum radiators by constantly supplying a corrosion inhibitor to the cooling water circulating inside. [Structure] At least a part of a corrosion suppressing container filled with a corrosion inhibitor 3 is a corroded plate material 1 made of an aluminum material exhibiting the same corrosiveness as a radiator tube. The container body 4 may be made of plastics. As the corrosion inhibitor 3, one or more selected from Y, Ce, La, Pr and Nd chlorides, sulfuric acid compounds and nitric acid compounds are used. The corrosion suppression container is attached to the inner wall of the header tank on the water channel side. [Effect] The corroded plate material 1 corrodes in accordance with the progress of the corrosion of the radiator tube, and the corrosion inhibitor 3 contained therein is eluted into the cooling water system through the portion opened by the corrosion.
The elution of the corrosion inhibitor 3 is started according to the progress of corrosion of the radiator tube, so that a good anticorrosion environment is maintained for a long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion suppressing container and a corrosion suppressing method for preventing internal corrosion occurring in a radiator mounted on a vehicle.

[0002]

2. Description of the Related Art Aluminum or aluminum alloys (hereinafter collectively referred to as aluminum materials) having good thermal conductivity have been used as radiator constituent materials.
When the cooling water circulates inside the radiator, the aluminum material is exposed to a corrosive atmosphere, and internal corrosion such as pitting corrosion progresses. Internal corrosion can be suppressed to some extent by using a brazing sheet as a constituent material.
The brazing sheet has, for example, an Al-Mn-based alloy as a core material, an Al-1% Zn alloy as a skin material on the surface on the cooling water side, and an Al-Si-based alloy as a brazing material on the opposite surface. There is. Zn in the skin material preferentially dissolves in the cooling water and exhibits a sacrificial anticorrosive action.

In order to reduce the weight of the radiator, the thickness of the brazing sheet has been reduced. However, the sacrificial anticorrosive action of the skin material decreases as the thickness decreases. In addition, when brazing fins etc. to a thin brazing sheet, the Nocolok brazing method that does not use corrosive flux is adopted, but the loss of Zn that evaporates at high temperature during brazing cannot be ignored. . Therefore, the decrease in corrosion resistance against the internal circulating water is a bottleneck in thinning the brazing sheet. As a means for improving the corrosion resistance of the radiator from the material standpoint, alloy design to which a low melting point metal such as Sn, In, Bi, etc., which enhances the sacrificial anode action, is added is also under study. However, low-melting-point metals such as Sn, In, and Bi have a high vapor pressure, and thus have a strong tendency to contaminate the melting furnace during slab production. Therefore, frequent in-furnace cleaning is required, which causes an increase in manufacturing cost. Moreover,
A large amount of Sn, In, Bi, etc. precipitates in the crystal grain boundaries that are the final solidified portion in the slab manufacturing process, and deteriorates the homogeneity of the slab. Further, since these low melting point metals are effective even in a small amount, when mixed with other alloys, they significantly impair the corrosion resistance and hinder recycling.

[0004]

Obtaining a thin-walled radiator tube corresponding to the weight reduction of a radiator by improving the plate thickness of an aluminum material and the skin material composition has various problems to be solved at present, Has not yet been adopted. On the other hand, antifreeze liquids, corrosion inhibitors, etc. for engine cooling systems, which are commonly used in automobiles, etc., have a reduced anticorrosion effect due to aging. Further, when the end user updates the cooling water, the antifreezing liquid and the corrosion inhibitor may not be added, and the radiator constituent material is exposed to an environment where internal corrosion such as pitting corrosion easily progresses. If pitting corrosion progresses extremely, through holes are formed in the constituent material of the heat exchanger, and it cannot be used as a heat exchanger. The present invention has been devised to solve such a problem, and by constantly adding a corrosion inhibitor to the cooling water system, the plate thickness of the radiator tube,
The purpose is to prevent corrosion of radiator constituent materials without being affected by the composition of the skin material and the presence or absence of antifreeze and corrosion inhibitors.

[0005]

In order to achieve the object, a corrosion inhibitor container of the present invention comprises a corrosion inhibitor for a container at least a part of which is made of an aluminum material having the same level of corrosiveness as a radiator tube. Is filled. As the corrosion inhibitor, one or two selected from chlorides of Y, Ce, La, Pr and Nd, sulfuric acid compounds and nitric acid compounds.
More than one seed is used. The aluminum material forming the container can have the same composition as the skin material of the radiator tube, for example. As a result, the container constituent material is exposed to the same corrosive environment as the radiator tube, and pitting holes for eluting the corrosion inhibitor inside are formed. It is also possible to use a two-layered material in which a skin material and a brazing material are clad in consideration of attachment to a header tank made of aluminum. The aluminum material clad with the brazing material also facilitates the operation of brazing and sealing the container containing the corrosion inhibitor.

The aluminum material is preferably thinner than the thickness of the radiator tube by 50 μm or more. As a result, the container is preferentially corroded, and the corrosion inhibitor inside is eluted. When a container is made of an aluminum material having an excessively large plate thickness, it takes time until the corrosion inhibitor starts to elute, and corrosion of the radiator constituent material proceeds excessively. Specifically, it is preferable to form the container with an aluminum material having a plate thickness of about 10 to 200 μm. A container filled with a corrosion inhibitor starts melting of the aluminum material (corrosion) and begins to elute the corrosion inhibitor, so only a part of the surface facing the cooling water circulation path is made of corrosive aluminum material. The other parts can be made of a permanent material such as plastic in consideration of attachment to peripheral members. A plurality of containers made of aluminum materials having different plate thicknesses may be used so that there is a time lag in dissolution of the aluminum material and elution of the corrosion inhibitor takes a long time.

The corrosion inhibitor to be filled in the container is preferably one having physical properties capable of flowing along with the cooling water circulating inside the radiator and sufficiently responding to changes in the amount of water. For example, those having a smaller area per unit weight than those having a small specific gravity such as sodium benzoate are used. In addition, it is preferable to use chlorides such as Y, Ce, La, Pr, Nd, etc., sulfuric acid compounds, nitric acid compounds, etc., since a small amount of them exerts a large corrosion inhibiting effect. The amount of the corrosion inhibitor is preferably set so that the concentration in the internal circulating water is 100 ppm or more. By maintaining this concentration, even if the antifreeze added to the cooling water system, the corrosion inhibitor, etc. deteriorates and the anticorrosion performance deteriorates, the cooling water should be replaced with tap water, which is highly corrosive to aluminum materials. Even in the case of being exposed, corrosion inside the radiator is surely suppressed.

The corrosion inhibitor can be filled into the container in various states, for example, as shown in FIG. Figure 1
(A) shows a support plate by corroding or adhering a corrosion inhibitor 3 between a corroded plate material 1 made of an aluminum alloy of the same material as the skin material and a support plate 2 made of the same material or a different aluminum alloy, and caulking or adhering. 2 is an example in which the peripheral portion of the corroded plate material 1 is fixed. FIG. 1B shows an example in which a similar corroded plate material 1 is brazed to a support plate 2. In this case, it is preferable to use a material in which the brazing material is clad in advance on the mating surfaces of the corroded plate material 1 and the support plate 2. Alternatively, as shown in FIG. 1 (c), it is also possible to use a container body 4 made of plastics with the corroded plate material 1 attached to the end face facing the internal circulating water side. It should be noted that the container body 4 may be provided with a thread 5 for facilitating attachment to the tank.

The corrosion suppressing container is attached to the inner wall of the header tank on the water channel side. The attachment means is not particularly limited as long as the container containing the corrosion inhibitor can be stably held for a long period of time, but various methods such as adhesion, fusion, brazing and mechanical fixing are adopted. can do. For example, in a heat exchanger having corrugated fins, as shown in FIG. 2, a tube 7 in which a large number of corrugated fins 6 are integrated is exposed to an internal space defined by a header plate 8 and a tank device wall 9. ing. Although a plate material made of plastics is used as the tank wall 9, it is also considered to use an aluminum plate as a part. The joint between the header plate 8 and the tank wall 9 is sealed with a packing 10.

In this heat exchanger, the internal space defined by the header plate 8 and the tank wall 9 serves as a cooling water circulation passage. Therefore, as shown in FIG. 3, the corrosion suppressing container 11 is attached. FIG. 3A shows an example in which the corrosion suppressing container 11 is fixed to the inner surface of the tank wall 9 by adhesion, brazing or the like. In the case of mounting by brazing, a plate material having a brazing material clad on its outer surface in advance may be used as the support plate 2 shown in FIG. 1A or 1B. Figure 3
FIG. 2B shows the female screw portion formed on the tank wall 9 as shown in FIG.
This is an example in which the screw thread 5 of the container body 4 shown in (c) is screwed. When the tank wall 9 is made of a synthetic resin material, the container body 4 is made of a heat-compatible material,
The container body 4 may be heat-sealed to the tank wall 9. Further, it is also possible to attach a plurality of corrosion inhibitor storage containers having different plate thicknesses to appropriate locations along the cooling water circulation path. The container constituent material is corroded in accordance with the progress of the corrosion of the radiator tube, and as shown in FIG. 5, for example, a through hole due to pitting occurs after a different period depending on the plate thickness. Therefore, by using a combination of corrosion-inhibiting containers having corroded plate materials with appropriate plate thicknesses, and varying the elution start time of the corrosion-inhibiting agent to be eluted from each corrosion-inhibiting container, the corrosion inhibitor can be used for a long period of time. Can be constantly eluted into the cooling water system.

[0011]

[Operation] In the corrosion inhibiting container 11 attached to the inner wall of the tank wall 9, the corroded plate material 1 is corroded when pitting corrosion starts to occur in the skin material layer of the tube 7. As a result, a hole is opened in the corrosion suppressing container 11, and the corrosion inhibitor contained therein is eluted into the circulating cooling water. The dissolved corrosion inhibitor flows along with the circulating flow of the cooling water to reduce the corrosive action of the cooling water.
As a result, a thinner aluminum material can be used as compared with a conventional radiator constituent material, and a radiator that meets the demand for weight reduction can be obtained.

[0012]

【Example】

Example 1 (Effect of Plate Thickness of Corrosive Plate on Time to Formation of Through Hole) As the corroded plate 1 and the support plate 2, an Al-1% Zn alloy plate was used. After subjecting the plate materials 1 and 2 to heat treatment at 600 ° C. for 3 minutes assuming brazing, YCl ₃ is sandwiched as a corrosion inhibitor 3 as shown in FIG.
The end portion of was sealed and a corrosion inhibiting container was produced. Further, in the same manner, a corrosion suppressing container was produced in which an Al-1% Zn alloy plate clad with an Al-10% Si brazing material with a clad ratio of 8% was used as the corroded plate material 1 and the support plate 2. The filling amount of the corrosion inhibitor 3 was set to 100 ppm or more based on the corrosive liquid in any of the corrosion inhibiting containers. The corrosion suppression container 11 was attached to the header tank of the aluminum material radiator 12 at the position shown in FIG. 4, and the corrosive liquid was circulated by the pump 15 through the radiator 12 → tank 13 → engine 14 → radiator 12. The engine 1
4 has a heater core 16 attached.

Sodium chloride, sodium sulfate and cupric chloride were added to deionized water and the pH was adjusted with an aqueous ferric chloride solution.
Chloride ion adjusted to 3, 1000 ppm, sulfate group 100
A corrosion acceleration test solution containing 0 ppm and 10 ppm of copper ions was prepared. Keep the corrosion acceleration test solution at 88 ± 1 ℃ and flow rate 35
After performing circulation for 8 hours at liter / min and then resting at room temperature for 16 hours, a corrosion test was performed, and the number of cycles until a through hole was formed in each corroded plate material 1 was investigated. When the investigation results were arranged in relation to the plate thickness of the corroded plate material, the results shown in FIG. 5 were obtained. In FIG. 5, the mark ◯ indicates an Al-1% Zn alloy plate, and the mark ● indicates Al-10.
The case where an Al-1% Zn alloy plate clad with a% Si brazing material is used as a corroded plate material is shown. As is clear from FIG. 5, it is understood that the time until the through hole is formed can be adjusted by changing the plate thickness of the plate to be corroded. Further, when the Al-1% Zn alloy having the same material as the skin material is used as the corroded plate material, the time taken to form the through holes is longer.

After the through holes are formed in the plate to be corroded,
The contained corrosion inhibitor gradually eluted into the corrosion promotion test solution, and the YCl ₃ concentration of the corrosion promotion test solution was maintained at 100 ppm or more. Therefore, the plate thickness of the corroded plate material 1 is adjusted so that the anticorrosive agent or the anticorrosive agent initially added to the cooling water system is deteriorated and the anticorrosive performance is deteriorated so that the anticorrosive agent flows out of the anticorrosive container 11. When adjusted, the corrosion inhibition effect is maintained for a long period of time. Also,
When a plurality of corrosion suppression containers 11 having different plate thicknesses of the corroded plate material 1 are attached to the inner wall of the cooling water circulation passage, a difference occurs in the time when the corrosion inhibitor flows out from each non-corrosion container 11,
Further, the corrosion inhibiting action is maintained for a long period of time.

Example 2 (Effect of Corrosion Inhibitor Type) As the corroded plate material 1 and the supporting plate 2, a plate thickness of 20 μm was used.
A 5 mm x 20 mm Al-1% Zn alloy plate was used.
After subjecting the plate materials 1 and 2 to a heat treatment of heating at 600 ° C. for 3 minutes assuming brazing, various corrosion inhibitors 3 are sandwiched as shown in FIG. A container for corrosion inhibition was produced by sealing with a mechanical caulking. Four corrosion-inhibiting vessels were attached, one at each end of the radiator 12 and the plastic tank that were incorporated in the corrosion test apparatus shown in FIG. An underwater curing type epoxy adhesive was used for mounting on the plastic tank. Further, as the radiator tube, the tube 7 having a thickness of 320 μm was initially used. Using the same corrosion acceleration test solution as in Example 1, a 180-cycle corrosion test was performed. After completion of the test, the tube 7 was cut open to remove corrosive organisms, and then the depth of pitting corrosion generated by the microscopic depth of focus method from the tube inner surface skin material was investigated. The depth of pitting corrosion is shown in Table 1 in relation to the type of corrosion inhibitor used, the filling amount and the like. Further, when the corrosion suppressing container was observed, general corrosion occurred, and it became thin and damaged.

[Table 1]

Example 3 As the corroded plate material 1 and the support plate 2, an Al-10% Si brazing material with a clad ratio of 8% was used.
15 mm with a plate thickness of 20 μm clad in a 1% Zn alloy plate
A plate material of × 20 mm was used. After filling the corrosion inhibitor, press the plate materials 1 and 2 with the brazing material layer inside,
The ends were sealed by brazing to produce the corrosion suppressing container of FIG. 1 (b). The corrosion suppression container was mounted inside the radiator having the tube 7 having an initial thickness of 320 μm as in Example 2, and a 180-cycle corrosion test was performed. After completion of the test, the tube 7 was cut open to remove corrosive organisms, and then the depth of pitting corrosion generated by the microscopic depth of focus method from the tube inner surface skin material was investigated. The depth of pitting corrosion is shown in Table 2 in relation to the type of corrosion inhibitor used, the filling amount, and the like. Further, when the corrosion inhibiting container was observed, almost the entire surface was corroded, and a corrosion hole having a large diameter was formed.

[Table 2]

Example 4 A container made of a plastic having an outer diameter of 13 mm, an inner diameter of 10 mm and a hollow portion height of 10 mm, which was hollow in the middle and was engraved with a male screw on the outer periphery of the solid part, was filled with a corrosion inhibitor, The end face of the hollow portion was covered with a corroded plate material having a plate thickness of 20 μm, which was the same as in Example 2 and Example 3, to prepare the corrosion suppressing container of FIG. Then, it was screwed into a radiator header in which a tube 7 having an initial thickness of 320 μm was incorporated, and a female screw portion provided in a reserve tank, and was fixed by using an adhesive together. A 180-cycle corrosion test was conducted in the same manner as in Example 2. After completion of the test, the tube 7 was cut open to remove corrosive organisms, and then the depth of pitting corrosion generated by the microscopic depth of focus method from the tube inner surface skin material was investigated. The depth of pitting
Table 3 shows the relationship between the type of the corrosion inhibitor used and the filling amount. Further, when the corrosion suppressing container was observed, almost all the surface of the corroded plate material was consumed and damaged.

[Table 3]

Comparative Example: The corrosion inhibiting containers of Test Nos. 53 and 54 had the structure shown in FIG. 1 (a) and were attached to the same locations as in Example 2 with an underwater curing type epoxy adhesive. The corrosion suppression containers of test numbers 55 to 57 had the structure shown in FIG. 1 (b), and were attached to the same locations as in Example 2 by brazing. This radiator also originally had the tube 7 having a thickness of 320 μm. Further, test number 58 is an example in which the corrosion suppression container is not used. A 180-cycle corrosion test was conducted in the same manner as in Example 2. After completion of the test, the tube 7 was cut open to remove corrosive organisms, and then the depth of pitting corrosion generated by the microscopic depth of focus method from the tube inner surface skin material was investigated. The depth of pitting corrosion is shown in Table 4 in relation to the type of corrosion inhibitor used, the filling amount and the like. Further, when the corrosion suppressing container was observed, it was found that corrosion had occurred almost on the front surface, and a corrosion hole having a large diameter was formed. As is clear from Table 4, when the amount of the corrosion inhibitor used was small, deep pitting holes were formed despite the same corrosion conditions. Moreover, in the test number 58 which does not use a corrosion suppression container, the pitting hole which penetrated the radiator tube 7 in the thickness direction was produced.

[Table 4]

Example 5: Corroded plate material (Al-1% Zn)
1 tank (2 in total) for corrosion inhibition with thicknesses of 20 μm and 40 μm, respectively, and 1 tank (2 in total) for corrosion inhibition with corroded plate thicknesses of 60 μm and 80 μm, respectively Attached to. 100ppm (57ppm in terms of Ce) CeCl based on the corrosion acceleration test liquid in each corrosion suppression container
₃ was enclosed. Initially, four corrosion suppressing containers were attached inside a radiator having a tube having a thickness of 320 μm. This radiator was subjected to the same corrosion test as in Example 2, and the corrosion acceleration test liquid was renewed after 30, 90 and 150 cycles had elapsed. Under this corrosive condition
The radiators were collected one by one after 0 and 150 cycles, and the tube 7 was cut open to investigate the occurrence of pitting corrosion.

When the measured maximum depth of pitting corrosion was arranged in relation to the corrosion cycle, the relationship shown in FIG. 6 was established. The maximum depth of pitting corrosion shows a steep rise every time the corrosion acceleration test solution is updated. This is because when the corrosion acceleration test liquid was renewed, the corrosion inhibitor that had dissolved in the liquid until then disappeared, and until the next container for corrosion inhibition was damaged,
This is because the skin material of the radiator tube 7 is corroded. Then, when the corrosion suppressing container is damaged, the corrosion suppressing agent is eluted into the liquid to prevent the radiator tube 7 from being corroded. In FIG. 6, points B, D, F and H are thicknesses 20 and 4 respectively.
Corresponding to the time when the corroded plate material of 0, 60 and 80 μm is broken, from this time until the corrosion acceleration test solution is renewed, the corrosion inhibitor is eluted into the solution from each corrosion inhibition container. As a result, the maximum pitting depth increases stepwise for each corrosion-promoting test liquid, as in O->B->C-> D.
The periods OB, CD, EF, and GH are the corrosion progressing process of the radiator tube 7 in the state where the corrosion inhibitor is not supplied, and the periods BC, DE, FG, and HI are the states where the corrosion inhibiting action of CeCl ₃ is working. Is.

For comparison, a radiator without a corrosion-suppressing vessel was similarly subjected to a corrosion test.
As shown by A, pitting corrosion that penetrates the tube wall of the radiator tube 7 occurred in about 80 cycles. Corrosion process O → B →
When C → D ... is compared with the corrosion progress status O → A, it can be seen that the life of the radiator tube 7 is significantly lengthened. When installing a corrosion suppression container made of corroded plates with different thickness to prevent corrosion of the radiator tube,
As shown in FIG. 6, every time several cycles have passed since the corrosive liquid was renewed, the corrosion suppressing containers were damaged one by one, and the internal corrosion inhibitor CeCl ₃ was eluted into the liquid. The eluted corrosion inhibitor CeCl ₃ forms a precipitate film on the aluminum surface in the liquid contact parts such as the tube 7 and the header to prevent aluminum corrosion. At this time, the corrosion inhibitor CeCl ₃ present in the liquid decreases as the amount of the formed precipitation film increases. In addition, all of the corrosion-inhibiting containers after the corrosion-inhibiting agent was eluted exhibited a frontal corrosion state, and were thin and damaged.

[0022]

As described above, according to the present invention, at least a part of the container filled with the corrosion inhibitor is formed by using the aluminum alloy of the same material as the skin material of the tube constituting the radiator as the corroded plate material. It forms the vessel wall. For example, when this corrosion suppressing container is attached to the inner wall of the header tank on the water passage side and the radiator is operated, the corroded plate material is corroded as the corrosion progresses of the tube, and the contained corrosion inhibitor is eluted into the circulating cooling water. . As a result, the corrosive effect of circulating cooling water is suppressed for a long time,
Corrosion of radiator components is prevented. This anticorrosion method makes it possible to use a thin plate material suitable for reducing the weight of the radiator without causing a problem due to the material surface of the aluminum material forming the tube or the like.

[Brief description of drawings]

FIG. 1 shows several examples of the corrosion inhibiting container of the present invention.

FIG. 2 Corrugated fin type heat exchanger in which a corrosion suppression container is installed

[Fig. 3] Internal structure with corrosion prevention container attached

[Fig. 4] Corrosion test device

[Fig. 5] Relationship between the number of cycles of corrosion test and the plate thickness until a through hole is formed in the plate to be corroded

FIG. 6 is a graph showing the progress of corrosion of a radiator tube when the corrosion suppression containers made of corroded plates having different thicknesses are used, by the change in the maximum pitting depth.

[Explanation of symbols]

1: Corroded plate material 2: Support plate 3: Corrosion inhibitor
4: Container body 5: Screw thread 6: Corrugated fin 7: Tube 8: Header plate 9: Tank device wall 10: Packing 11: Container
12: radiator 13: reserve tank 14:
Engine 15: Motor 16: Heater core

Claims (3)

[Claims] 1. A corrosion-suppressing container in which a corrosion inhibitor is filled in a container at least a part of which is made of an aluminum material exhibiting the same level of corrosiveness as a radiator tube. 2. The corrosion inhibitor according to claim 1, wherein Y, Ce,
A corrosion inhibiting container comprising one or more selected from La, Pr and Nd chlorides, sulfuric acid compounds and nitric acid compounds. 3. A corrosion-suppressing container, at least a part of which is formed of a corroded plate material exhibiting a corrosiveness similar to that of a radiator tube, is filled with a corrosion-suppressing agent, and the corrosion-suppressing container is used as an inner wall of a header tank on the water channel side. A method for suppressing corrosion of a radiator, characterized in that the corrosion suppression container is corroded in accordance with the progress of corrosion of the radiator tube, and the corrosion inhibitor is eluted into a cooling water system.