KR102282585B1 - Corrosion resistant heat exchanger using the control of alloy composition and potential - Google Patents

Abstract

The present invention relates to the improvement of corrosion resistance of aluminum tubes, fins and headers, which are heat exchanger components. His composition is; One or more tubes of aluminum alloy material, one or more headers, one or more brazing header clads, one or more fins (or heat sinks), and one or more brazing fins. clad; The corrosion potential of the tube is in the range of -950mV to -650mV; The corrosion potential of the header is in the range of 0mV to +150mV based on the corrosion potential of the tube; The corrosion potential of the header clad is in the range of -20mV to +100mV based on the corrosion potential of the tube; The Cu content of the aluminum alloy is 0.001 to 0.50% by weight; The Zn content of the aluminum alloy is 0.001 to 5.00 wt%; and the tube, header and fin are joined by a brazing process by the header clad material and the pin clad material.

Description

High corrosion resistance heat exchanger system using the control of alloy composition and alloy potential {Corrosion resistant heat exchanger using the control of alloy composition and potential}

The present invention relates to a heat exchanger system, and more particularly, to an improvement in corrosion resistance of aluminum tubes, fins and headers, which are heat exchanger components. In particular, it relates to the improvement of corrosion resistance due to the appropriate selection of corrosion potentials for each part and the addition of special elements.

In general, for heat exchangers such as evaporators, condensers, and piping, aluminum or aluminum alloy materials having good light weight and good thermal conductivity are used. In these heat exchangers, a condenser tube and a fin (or a heat sink) made of an aluminum alloy extruded material, a header pipe, and various pipes are constituted. These heat exchangers are generally assembled by a tube and a fin (generally, a fin core is coated with or clad with a brazing plate) in a predetermined structure, and then brazed and joined in an inert gas atmosphere. is completed

Materials of the A 1XXX series and A 3XXX series are widely used as materials for heat exchangers, and when more strength is required, some of the A 6XXX series materials are also used. In addition, A 4XXX series is widely used as a clad material used for brazing tubes and pipes to pins and header pipes.

Since the extruded tube and pipe of the heat exchanger are used as a refrigerant passage pipe, if penetration occurs due to corrosion during use, refrigerant leakage occurs and the function as a heat exchanger cannot be performed. For this reason, conventionally, Zn (zinc) is attached to the surface of an extruded tube by thermal spraying or the like, and Zn is diffused by brazing (solder). For this reason, the Zn diffusion layer formed on the surface layer of the tube acts as a sacrificial anode with respect to the deep part, suppressing corrosion in the plate thickness direction and extending the corrosion penetration life. In this case, a Zn adhesion process of Zn coating (thermal spraying, etc.) is required after the tube is extruded, resulting in an increase in manufacturing cost.

In particular, from the viewpoint of corrosion resistance of the tube, Japanese Patent Application Laid-Open No. 11-21649 contains 0.15 to 0.35 wt% of iron, 0.15 wt% or less of silicon, less than 0.03 wt% of zinc, 0.55 wt% of copper, and 0.02 to 0.05 wt% of zirconium. %, containing 0.003 to 0.010% by weight of titanium, iron/silicon≥2.5, and the remainder has been proposed an aluminum alloy composed of aluminum and unavoidably added impurities.

However, in the alloy of the above patent document, copper was added as an additive element to secure the corrosion resistance of the alloy, but a large amount of copper (0.55% by weight) was added, so that a large number of Al-Cu-based intermetallic compounds were formed, resulting in lower extrusion properties, Due to the precipitation of the intermetallic compound, there is a problem in that the corrosion potential is lowered in the local region of the base material (material), and the corrosion resistance property is deteriorated.

In order to improve this, Korean Patent Laid-Open Publication No. 10-2011-0072237 proposes a method for omitting the Zn spraying process on the outside of the tube by adding Zr and B to an aluminum alloy containing .15 to 0.45% copper. there is. The literature contains the technical idea that corrosion resistance increases by refining the crystals of the aluminum alloy due to the effect of adding Zr or B. However, when the copper content is 0.1% by weight or more, copper is precipitated at the grain boundary during the operation of the heat exchanger, and as a result, the sensitivity to intergranular corrosion is increased, and intergranular corrosion of the tube occurs, thereby shortening the corrosion penetration life of the tube. .

In the case of the above documents, although Cu was added as a main element to improve corrosion resistance, the disadvantages of adding Cu were not sufficiently overcome.

Then, in order to increase corrosion resistance in Korean Patent Laid-Open No. 10-2014-0000406 because of the disadvantage of adding Cu, copper (Cu) is minimized to 0.01% or less, and manganese (Mn) of 0.50 to 1.0% by weight and 0.2% by weight of manganese (Mn) Although 0.05 to 0.15 wt% of zirconium (Zr) is added to the following silicon (Si) composition, the advantage of increasing the corrosion potential of Cu is sacrificed due to the removal of Cu, and the potential due to contact when assembling each part of the heat exchanger It is difficult to adopt in a heat exchanger system because it limits the design.

Therefore, in the present invention, in order to compensate for the disadvantages of the prior art, the cathodic protection principle was applied to individual parts of the heat exchanger to maximize corrosion resistance.

Japanese Patent Laid-Open No. 11-21649 Domestic Patent Publication No. 10-2011-0072237 Domestic Patent Publication No. 10-2014-0000406 Domestic Registered Patent No. 10-1335680 Domestic Registered Patent No. 10-1349359 Domestic Registered Patent No. 10-1194970

An object of the present invention for the above problems is to solve the above problems in order to improve the corrosion resistance of the heat exchanger. An object of the present invention is to extend the lifespan of a heat exchanger system by preventing leakage of refrigerant by maintaining airtightness of a heat exchanger even in a harsh environment by improving corrosion resistance.

The above purpose is; One or more tubes made of aluminum alloy, one or more headers, one or more brazing header clads, one or more fins (or heat sinks), and one or more brazing fins. clad;

The corrosion potential of the tube is in the range of -950mV to -650mV;

The corrosion potential of the header is in the range of 0mV to +150mV based on the corrosion potential of the tube;

The corrosion potential of the header clad is in the range of -20mV to +100mV based on the corrosion potential of the tube;

The Cu content of the aluminum alloy is 0.001 to 0.50% by weight;

The Zn content of the aluminum alloy is 0.001-5.00% by weight;

It is achieved by a high corrosion resistance heat exchanger system using the adjustment of alloy composition and alloy potential, characterized in that the tube, header and fin are joined by a brazing process by the header clad material and the fin clad material.

According to a feature of the present invention,

The corrosion potential of the fin (or heat sink) may be in the range of -20mV to -170mV based on the corrosion potential of the tube.

According to another feature of the present invention,

The corrosion potential of the fin clad material may be in the range of -40mV to +80mV based on the corrosion potential of the tube.

According to another feature of the present invention,

In the aluminum alloy, a change in the content of at least one selected from Cu, Zn, Mn, Si, Fe, and Mg may be a main corrosion potential control factor.

According to another feature of the present invention,

The aluminum alloy may contain at least one selected from rare earth metals having atomic numbers 57 (La) to 71 (Lu) in an amount of 0.005 to 1.00 wt%.

According to another feature of the present invention,

The aluminum alloy may contain at least one selected from Zr and B in an amount of 0.005 to 0.25 wt%.

According to another feature of the present invention,

Any one of age hardening heat treatment, zinc coating, chemical conversion coating, resin coating, or a combination thereof may be further added to any one of the tube, fin (or heat sink), header, or a combination thereof.

Another object of the present invention is to

The content of Cu is 0.001 to 0.50% by weight;

The content of Zn is 0.001-5.00% by weight;

Zr, the content of at least one selected from B is 0.001 to 0.25% by weight;

The content of at least one selected from among rare earth metals (atomic numbers 57 (La) to 71 (Lu)) is 0.001 to 1.00 wt%;

S% in the formula below is 0.05 to 0.30 wt%;

It is achieved by a high corrosion resistance heat exchanger system using the adjustment of alloy composition and alloy potential, characterized in that it includes a tube made of an aluminum alloy material that satisfies (however, the range of M in the formula below is 1 to 5) .

(formula)

Z% = Zr, the content of at least one selected from B,

R% = content of at least one selected from atomic numbers 57 (La) to 71 (Lu)),

S% = ( (R% / M) + Z% ) where

Content of group Cu is 0.001 to 0.12 weight%;

The content of group n is 0.001 to 3.00 wt%

The content of the group Fe is 0.001 to 0.25 wt%

The content of at least one selected from among rare earth metals having atomic numbers 57 (La) to 71 (Lu) is 0.05 to 0.50 wt%;

Zr, the content of at least one selected from B is 0.01 to 0.07% by weight; may include a tube made of an aluminum alloy material containing.

According to another feature of the present invention,

The aluminum alloy may include Fe in the range of 0.40 to 0.70 wt %.

According to another feature of the present invention,

The aluminum alloy is one selected from Mn, Mg, Si, Fe, Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Sc, Nb, Hf, or Y More may be included.

According to the present invention, in an aluminum alloy used for a heat exchanger, corrosion resistance can be improved by adjusting the corrosion potential for each individual component in order to improve corrosion resistance. In addition, by adding special elements such as rare earth metals to improve the composition, corrosion resistance and strength can be further improved. Due to this, it is possible to achieve the simplification of the manufacturing process and cost reduction due to the increase in the lifespan of the parts, the omission of the zinc coating process, and the omission of the additional post-treatment process.

1 is a diagram showing a preferred distribution of corrosion potential of a heat exchanger tube, fin, header and clad according to the present invention.
2 is a diagram showing a more preferable corrosion potential distribution of the heat exchanger tube, fin, header and clad according to the present invention.
3 is a schematic perspective view of a heat exchanger system according to an embodiment of the present invention.

Hereinafter, selection of a material for a heat exchanger and a system configuration according to the present invention will be described with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments and configurations described in this specification are only the most preferred embodiment of the present invention and do not represent all of the technical spirit of the present invention, so various equivalents and modifications that can be substituted for them at the time of the present application It should be understood that there may be

The heat exchanger system 1 generally has a support structure and includes a header 3 in the form of a pipe, a plurality of tubes 5 connecting the header 3 to each other, and a pipe thinner than the header 3 and , has a configuration including a fin (or heat sink) 7 interposed between the tube (5) to increase the heat transfer rate. The fins 7 may be provided in a corrugated form to increase the heat exchange area as shown. A heating medium may be communicated between the header 3 and the tube 5 . And the header 3 and the tube 5 and the tube 5 and the pin 7 can be joined by brazing, respectively. Hereinafter, the term "fin" means that a heat sink is included in the present invention.)

When the tube 5 made of aluminum is corroded through the heat exchanger system 1, the refrigerant flows out and the life of the tube 5 ends. Since aluminum alloys are sensitive to pitting corrosion, many efforts have been made to prevent pitting corrosion. First, as a method through control of the alloy composition, the content of Si, Fe and Cu to form precipitates with high corrosion potential, that is, Si, FeAl ₃ , Cu, CuAl _{2, etc., which become a local cathode, are lowered, and combined with Si, Fe} There is a method of alloying Mn or Mg to form a phase with a low potential. As a heat treatment method, there is a method of avoiding heat treatment at around 500° C. where a lot of precipitates acting as a cathode occur.

As a method from a macroscopic point of view, there is a cathode protection method that increases the corrosion potential of the material to be protected compared to other contact materials. In the present invention, the cathodic corrosion protection method and the alloy composition control method are mixed and applied.

The effects of Cu, Zn, Mn, Fe, Si, and Mg, which are major alloying elements in aluminum alloy, on the properties of the alloy are as follows.

① Cu alloy element Cu is dissolved in the matrix to increase the strength of the aluminum alloy, but has the disadvantage of significantly lowering the extrudability compared to Mn. It is known that the addition of Cu increases the corrosion potential. When Zn and Cu coexist, especially when the Zn content is small, the potential increasing effect by Cu is dominant. That is, when there is much Cu content, the potential raising effect by Cu becomes more dominant than the potential lowering effect by Zn. When the content is less than 0.12% by weight, the effect of adding copper such as corrosion resistance is difficult to appear, and when the content exceeds 0.45% by weight, extrudability and corrosion resistance are simultaneously reduced (the content here is a ratio to the total weight of the aluminum alloy). All content indications in the description and claims of the present invention are the same). When Cu is more than an appropriate content, there is a tendency to form precipitates at grain boundaries, which increases the sensitivity to intergranular corrosion and local corrosion.

② Zn

The alloying element Zn coexists with Mg to improve mechanical properties. In general, when Zn is added, the corrosion potential is lowered, but the amount of change in the corrosion potential is small compared to Cu.

③ Mn

The alloying element Mn increases the strength of the aluminum alloy. When the Mn content is less than 0.5% by weight, the effect of increasing the strength is small, and when it exceeds 1.2 to 1.7% by weight, the extrudability decreases. With the addition of n, compared with the case of adding the same amount of Si, Cu or Mg, the decrease in extrudability, especially the limiting extrusion rate, is remarkably small. In addition, it has an effect of increasing the corrosion potential of the alloy by precipitation as a fine intermetallic compound of _{Al 6 Mn.} When the content is less than 0.6% by weight, the effect of adding manganese such as corrosion resistance is small. In addition, there is an effect of removing the bad effect of adding Fe and a crystal grain refinement effect, and a compound that does not impair corrosion resistance is formed. Therefore, it is possible to improve the strength without lowering the corrosion resistance. However, care must be taken as excessive manganese may lower the mechanical strength of the aluminum alloy.

④ Fe

The alloying element Fe is an element that is precipitated as an intermetallic compound in an Al alloy and improves wear resistance. If the content is less than 0.1wt%, there is almost no anti-abrasion effect, and if it exceeds 0.3wt%, the particles are coarsened and processability is deteriorated.

_{In addition, Al 3} Fe compound is formed even in a very small amount, and it is combined with Si to form an Al-Fe-Si intermetallic compound, which is a factor of deterioration of mechanical properties. Even a small amount deteriorates the surface gloss and weakens corrosion resistance and ductility. In addition, there is an effect of grain refinement by preventing recrystallization grain coarsening. When Fe is added in an amount of 0.5 wt % or less in the die casting process, there is an effect of preventing burning in the mold.

⑤ Si

The alloying element Si is precipitated as an Al-Mn-Si-based intermetallic compound to inhibit grain growth by interfering with grain boundary movement, and to improve extrudability by reducing deformation resistance during extrusion. If it is less than 0.05% by weight, the casting cost increases, and if it is more than 0.10%, an Al-Mn-Si-based intermetallic compound is formed in the alloy, so that the Mn solid solubility in the alloy is reduced. This may lead to a drop in corrosion potential. In addition, when the content exceeds 0.2% by weight, the strength of the alloy is increased and extrudability is reduced.

⑥ Mg

The alloying element Mg increases the strength by solid solution strengthening in the matrix, but decreases the extrudability as the amount increases. When the addition amount exceeds 2.0 wt%, since a compound having a high melting point is formed due to a reaction with the flux, etc., there is a tendency for the bonding property to be significantly reduced in the brazing process. In addition, when it exceeds 3.5% by weight, Mg ₂ Al ₃ is precipitated and the susceptibility to intergranular corrosion or stress corrosion is increased.

In addition, depending on the coexistence of Si and Zn, aging strengthening characteristics may occur. It has excellent cutting machinability, particularly good corrosion resistance to seawater, and reduced shrinkage during solidification. In addition, since the fluidity of the molten metal is weakened and especially the binding force with oxygen is strong, it is necessary to be careful about the introduction of oxides. The composition of the aluminum alloy for a heat exchanger may be appropriately selected in consideration of the characteristics of the main alloying elements and their influence on corrosion resistance. Alloys widely used in heat exchangers are alloys of the A 1XXX series and A 3XXX series. Table 1 below shows the composition of representative alloy types.

alloy name Zn Mn Si Cu Fe etc. Al A1070 0.04max 0.03max 0.2max 0.04max 0.25 max 0.15max Rem A3003 0.1max 1.0-1.5 0.6max 0.05-0.20 0.7max 0.15max Rem

In a typical aluminum alloy, the corrosion potential is most affected by Cu, and the corrosion potential is in the range of -950 mV to -650 mV in the range of 0.01 to 0.5 wt% depending on the copper content. Therefore, ignoring the influence of other alloying elements, the corrosion potential can be easily changed by adding or reducing a small amount of copper in an aluminum alloy. In addition, in the case of zinc, the corrosion potential decreases by about 30-40 mV as 1.0 wt % is increased in a typical aluminum alloy, so the range of change is smaller than that of Cu. Therefore, it is possible to additionally control the corrosion potential even with the zinc content. In addition, Mn has the effect of increasing the corrosion potential, and Si has the effect of lowering the corrosion potential. Therefore, it is possible to easily change the corrosion potential of the aluminum alloy by changing the content of alloying elements such as Cu, Zn, Mn, Si, Mg, and Fe. For example, by adjusting the content of copper and zinc for A1070 and A3003, the corrosion potential of the alloy can be changed.

In general, in the case of an aluminum alloy for a heat exchanger, the Zn content is preferably 5.0 wt% or less, and the Cu content is preferably 0.5 wt% or less. Therefore, in the case of the tube as well, since the Cu content is preferably 0.5 wt% or less, the corrosion potential of the tube is preferably in the range of -950 to -650mV, and more preferably in the range of -850 to -650mV.

On the other hand, as described above, there is a cathodic corrosion protection method as a method of preventing penetration corrosion of the tube. In this case, a suitable component as a sacrificial anode is a pin. In the case of fins, even if penetration corrosion occurs, there is no risk of refrigerant leakage. Therefore, in order to perform cathodic corrosion of the tube, the corrosion potential of the fin should be lower than the corrosion potential of the tube, and the range is preferably in the range of -20mV to -170mV, and more preferably in the range of -20mV to -100mV. If the difference is too small, the effect of cathodic protection is insignificant, and if the difference is too large, the corrosion rate of the fin is too high. Therefore, when the material of the fin is A3003, if the copper content is reduced or the zinc content is increased, the corrosion potential is lowered. The corrosion resistance of the tube is improved when a fin with a lowered corrosion potential is combined with zinc. Also, in general, a portion where the refrigerant of the heat exchanger easily flows out due to corrosion is the junction of the tube 5 and the header 3 . In particular, although penetration corrosion of the header 3 did not occur, at the tube/header junction, even if only a portion of the header 3 is corroded in the vertical direction of the contact surface with the tube, leakage occurs. have to lean Conversely, since the tube 5 has a constant tube thickness in the depth direction of the junction, leakage of the refrigerant is prevented until the entire thickness is penetrated. Therefore, since it is necessary to strengthen the corrosion resistance of the header 3 rather than the tube 5 , it is preferable that the corrosion potential of the header 3 is higher than the corrosion potential of the tube 5 . The difference is preferably in the range of +0 mV to +150 mV, more preferably in the range of +20 mV to +100 mV.

In addition, the heat exchanger system 1 is usually assembled with the tube 5, the fin 7, and the header 3, and then the parts are joined by brazing, and for this purpose, a brazing clad is provided outside the fin core. (fin clad) Aluminum alloy is joined. In the case of the header 3 as well, the clad material is present in the portion where it is coupled to the tube 5 . This clad material is melted in the brazing process and serves to join the parts. In the case of tube/fin and tube/header joints, it is desirable to have high corrosion resistance for electrical contact maintenance and structural stability.

In the case of the clad material of the tube/fin, since the corrosion potential of the fin 7 is low, the range of -40 to +80 mV is preferable compared to the corrosion potential of the tube 5, and the range of +0 to +80 mV is more preferable. In the case of the clad material of the tube/header, since the corrosion potential of the header 3 is high, it is preferable to be slightly higher than the clad material of the tube/fin. The range is preferably in the range of -20 to +100 mV, more preferably in the range of +10 to +90 mV, compared to the corrosion potential of the tube (5).

Corrosion potential relationships between these components are shown in FIGS. 1 and 2 . FIG. 1 is a diagram showing a region of a preferred corrosion potential of the fin 7, a header 3, and a clad material with a tube 5 as the center, and FIG. 2 is a diagram showing a region of a more preferred corrosion potential.

On the other hand, as a method of alleviating penetration corrosion of the tube 5, it can be achieved by adding the following alloying elements.

Zr (zirconium) and B (boron)

Zirconium (Zr) not only improves the strength by refining the size of crystal grains, but also has the effect of suppressing the occurrence of pitting corrosion that occurs locally by finely dispersing the precipitates that generate the potential difference. Due to this, there is a characteristic of inducing corrosion to occur uniformly over the entire area. In addition, it improves the extrusion properties by reducing the deformation resistance of the extrusion process, and at the same time suppresses grain coarsening after brazing to improve strength. If it is less than 0.005% by weight, there is no effect, and if it is more than 0.25% by weight, it is preferable to use less than 0.25% by weight because the difficulty of extrusion and economic cost increase occur. Boron exhibits similar effects to zirconium when added to aluminum alloys.

⑧ Rare Earth metal (RE)

The effect of adding the rare earth metal according to the present invention is as follows.

Rare earth metals with atomic numbers 57 (La) to 71 (Lu) reduce the cathodic reaction of local corrosion caused by the precipitates deposited in the matrix, and consequently have the effect of reducing the local corrosion anodic reaction of the surrounding area, so local corrosion is alleviated acts to make In addition, corrosion resistance is strengthened by reducing components such as Fe and Ni, which are elements that are weak in corrosion resistance, present in the molten metal during aluminum production. Therefore, even when the concentration of impurities such as Fe is 0.2% by weight or more, it is helpful to maintain corrosion resistance.

In addition, since the rare earth metal has an effect of increasing the corrosion potential, it is possible to minimize the addition of Cu or to replace Cu for the purpose of increasing the corrosion potential. Therefore, when the Cu content is increased to increase the corrosion potential, there is an effect of minimizing these side effects, and thus the corrosion resistance is improved.

In addition, by improving the ductility and adhesion of the oxide film formed at the grain boundary or the surface, the lifespan of the oxide film is extended and corrosion resistance is improved. In addition, it has the effect of improving the plastic workability of the metal by increasing the strength and fluidity of the aluminum alloy, and improving the brazing properties.

Since the effect of improving the corrosion resistance of rare earth metals is about 20% to 100% compared to that of Zr, a similar effect can be realized with 1 to 5 times the amount of Zr. Using this, it can be a useful means to replace the expensive Zr.

In the present invention, excellent corrosion resistance was obtained by adding a rare earth metal in order to prevent the aluminum alloy from becoming vulnerable to local corrosion and intergranular corrosion. At this time, the appropriate amount of the rare earth element added is preferably in the range of 0.005 to 1.0 wt%, and more preferably in the range of 0.01 to 0.60 wt% or 0.05 to 0.50 wt%.

Although a lot of research and development is being carried out on rare earth metals due to their beneficial properties, the development activities are mainly in the field of increasing the corrosion resistance of magnesium (alloy), the field of increasing the strength of some aluminum alloys for casting, and conversion coating on the surface of the aluminum alloy. It has been focused on the field of increasing corrosion resistance.

However, to date, it is difficult to find any related literature in which rare earth elements are directly added to alloys to improve properties such as corrosion resistance in 1XXX, 3XXX, and 6XXX series and 4XXX series for brazing among aluminum alloys for machining.

However, in very few literature records of the A 1XXX series and A 4XXX series can be found. The document is disclosed in domestic registered patent No. 10-1335680, domestic registered patent No. 10-1349359, and domestic registered patent No. 10-1194970, but the content is different from the present invention.

other elements

In all the above cases, the aluminum alloy contains alloying elements (Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Y) widely used in the aluminum industry and unavoidable impurities. It may additionally include more.

On the other hand, according to the present invention, when greater corrosion resistance is required, the sacrificial anode effect is applied to any one of the tube (5), fin (7), header (3), or a combination thereof with zinc coating (spraying, etc.) may be given, and corrosion resistance may be increased by additionally applying chemical conversion coating. In addition, corrosion resistance may be further improved by additionally applying silicone or resin coating to the surface of the heat exchanger component according to the present invention, and additional age hardening heat treatment may be performed if necessary to increase strength.

(Example)

Hereinafter, in order to help the understanding of the present invention, it will be described in more detail. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

The composition (wt%) of the aluminum alloy according to one preferred embodiment of the present invention may be as shown in Table 2 below. This alloy shows the composition of A 3003 alloy and A 4343 alloy, which are currently widely used, and each alloy may contain more unavoidable impurities.

alloy type Zn Mn Si Cu Fe Other Al A 3003 Spec. 0.1max 1.0-1.5 0.6max 0.05-0.20 0.7max 0.15max Rem. A 4343 Spec. <0.20 <0.10 6.8-8.2 <0.25 <0.80 0.15max Rem.

Table 3 shows the types of alloys used in the present invention. The material of A3003 was used as the basic material (alloy symbol b) of the tube, pin and header, and the material of A4343 was used as the basic material of the brazing clad (alloy symbol h). In the case of A3003, alloys with increased corrosion potential by adding copper are indicated as high corrosion potential 1 (alloy symbol a) in Table 3, and alloys with reduced corrosion potential by adding zinc are indicated by low corrosion potential 1 (alloy symbol c) in Table 3 ) is indicated.

In addition, the alloy with alloy symbol b as a base and containing La, a rare earth metal, was denoted as improved alloy 1 (alloy symbol d), and the alloy containing Zr was denoted as improved alloy 2 (alloy symbol e), with La and The alloy to which Zr was simultaneously added was designated as improved alloy 3 (alloy symbol f). In addition, in alloy symbol h, which is a clad material, an alloy whose corrosion potential was increased by increasing copper was denoted as high corrosion potential 2 (alloy symbol g), and an alloy in which corrosion potential was reduced by decreasing copper was denoted as low corrosion potential 2 (alloy symbol g). It is denoted as i).

alloy type corrosion potential alloy symbol Zn Mn Si Cu Fe etc. La Zr Al high corrosion potential1 -670 a 0.05 1.20 0.30 0.25 0.40 0.15max - - Rem Basic alloy (A3003) -720 b 0.05 1.20 0.30 0.12 0.40 0.15max - - Rem low corrosion potential1 -770 c 1.50 1.20 0.30 0.12 0.40 0.15max - - Rem improved alloy 1 -700 d 0.05 1.20 0.30 0.10 0.40 0.15max 0.15 - Rem Improved alloy 2 -710 e 0.05 1.20 0.30 0.12 0.40 0.15max - 0.05 Rem Improved alloy 3 -700 f 0.05 1.20 0.30 0.10 0.40 0.15max 0.15 0.05 Rem high corrosion potential2 -700 g 0.10 0.05 7.5 0.25 0.45 0.15max - - Rem Clad (A4343) -720 h 0.10 0.05 7.5 0.20 0.45 0.15max - - Rem low corrosion potential2 -740 i 0.10 0.05 7.5 0.15 0.45 0.15max - - Rem

Table 4 shows the results of assembling the aluminum alloy prepared in this way into a heat exchanger by selecting the material for the tube, fin, header and clad. For example, in the case of sample number 1, the material of the tube, pin, and header is selected as alloy symbol b, and the clad material is selected as h. A total of 12 samples were made in 3 sets each.

In order to evaluate the corrosion resistance characteristics of the heat exchanger system, SWAAT evaluation was performed according to the ASTM standard, and the results are shown in Table 4. At this time, the result value was expressed as the average value of 3 sets. SWAAT evaluation is a test according to ASTM standard G85. Glacial acetic acid was added to a 4.2% by weight NaCl solution to maintain pH 2.8 to 3.0, and spraying at a pressure of 0.07 MPa under a temperature atmosphere of 49 ° C. was performed. At this time, the spray amount was maintained at 1 to 2 ml/hr.

Part type sample No. One 2 3 4 5 6 7 Tube alloy symbol b a a b b c c pin alloy symbol b b c a c a b header alloy symbol b c b c a b a Clad alloy symbol h h h h h h h SWAAT Leak
Time (hr) 504 645 1032 576 1416 432 528 Part type sample No. One 5 8 9 10 11 12 Tube alloy symbol b b d e f f f pin alloy symbol b c c c c c c header alloy symbol b a a a a a a Clad alloy symbol h h h h h g i SWAAT Leak
Time (hr) 504 1416 1824 1704 2160 2304 1320

As can be seen from Table 4 above, when the same cladding material (alloy symbol h) is used and the corrosion potential of the tube 5, pin 7, and header 3 is changed (Samples 1 to 7), Sample No. 5 showed the best corrosion resistance. This corresponds to the case where the order of corrosion potential is header>tube>pin. In addition, in the case of Sample Nos. 8 to 10, La (Sample No. 8), Zr (Sample No. 9) and La+Zr (Sample No. 10) were added to the tube in Sample No. 5, and the addition of rare earth metal and zirconium improved corrosion resistance. has been shown to strengthen In the case of Sample Nos. 10 to 12, the corrosion potential of the clad material was changed based on Sample No. 10. It has been shown that corrosion resistance is weakened when the potential of the clad material is lower than that of the tube (Sample No. 12).

In the above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto and will be described below with the technical idea of the present invention by those of ordinary skill in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims.

1: heat exchanger system 3: header
5: tube (tube) 7: fin (fin)

Claims (11)

One or more tubes, one or more headers, one or more brazing header clads, one or more fins (or heat sinks), one or more brazing, each of aluminum alloy material In the heat exchanger system having a fin clad for
The corrosion potential of the tube is in the range of -950mV to -650mV;
The corrosion potential of the header is in the range of 0mV to +150mV based on the corrosion potential of the tube;
The corrosion potential of the header clad is set in the range of -20mV to +100mV based on the corrosion potential of the tube;
The Cu content of the aluminum alloy is 0.001 to 0.50% by weight;
Zn content of the aluminum alloy is 0.001-5.00% by weight; characterized in that the composition,
High corrosion resistance heat exchanger system using the adjustment of alloy composition and alloy potential, characterized in that made of an aluminum alloy material.
According to claim 1,
The corrosion potential of the fin (or heat sink) is in the range of -20mV to -170mV based on the corrosion potential of the tube, High corrosion resistance heat exchanger system using the adjustment of alloy composition and alloy potential.
According to claim 1,
The corrosion potential of the fin clad is in the range of -40mV to +80mV based on the corrosion potential of the tube, The high corrosion resistance heat exchanger system using the adjustment of the alloy composition and the alloy potential.
According to claim 1,
In the aluminum alloy, a change in the content of at least one selected from Cu, Zn, Mn, Si, Fe, or Mg is a main corrosion potential control factor, a high corrosion resistance heat exchanger system using alloy composition and adjustment of alloy potential .
According to claim 1,
The aluminum alloy is characterized in that it contains at least one selected from among rare earth metals of atomic numbers 57 (La) to 71 (Lu) in an amount of 0.005 to 1.00 wt %, high corrosion resistance using alloy composition and adjustment of alloy potential heat exchanger system.
According to claim 1,
The aluminum alloy contains at least one selected from Zr and B in an amount of 0.005 to 0.25 wt%, a high corrosion resistance heat exchanger system using the adjustment of alloy composition and alloy potential.
According to claim 1,
An alloy composition characterized in that the tube, fin (or heat sink), header, or any one of a combination thereof is further subjected to a process of any one of age hardening heat treatment, zinc coating, chemical conversion coating, resin coating, or a combination thereof. High corrosion resistance heat exchanger system using the control of the alloy potential.
One or more tubes, one or more headers, one or more brazing header clad, one or more fins (or heat sink), one or more brazing materials, made of aluminum alloy. A heat exchanger system having a fin clad, comprising:
The content of Cu is 0.001 to 0.50% by weight;
The content of Zn is 0.001-5.00% by weight;
Zr, the content of at least one selected from B is 0.001 to 0.25% by weight;
The content of at least one selected from among rare earth metals (atomic numbers 57 (La) to 71 (Lu)) is 0.001 to 1.00 wt%;
S% in the formula below 0.05 to 0.30% by weight;
For (where the range of M in the formula below is 1 to 5) and with the alloy composition and control of alloy potential, characterized in that it comprises a tube made of a corrosion-resistant aluminum alloy material with satisfactory heat exchanger system.
<Equation 1>
S% = (R% / M) + Z%
( However, the range of M in Equation 1 is 1 to 5, the Z% = Zr, the content of at least one selected from B, and R% = atomic number 57 (La) to 71 (Lu)) selected one or more content)
9. The method of claim 8,
Cu content is 0.001 to 0.12 weight%;
Zn content is 0.001 to 3.00 wt%
Fe content is 0.001 to 0.25 wt%
The content of at least one selected from among rare earth metals having atomic numbers 57 (La) to 71 (Lu) is 0.05 to 0.50 wt%;
Zr, the content of at least one selected from B is 0.01 to 0.07% by weight; a high corrosion resistance heat exchanger system using the alloy composition and alloy potential adjustment made of an aluminum alloy material containing.
9. The method of claim 8,
High corrosion resistance heat exchanger system using the adjustment of alloy composition and alloy potential, characterized in that the aluminum alloy contains Fe in the range of 0.40 to 0.70 wt%.
According to claim 1,
Any one or more of the tube, header, brazing header clad, fin (or heat sink), and brazing fin clad, each made of the aluminum alloy,
One selected from Mn, Mg, Si, Fe, Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Sc, Nb, Hf, or Y in the aluminum alloy High corrosion resistance heat exchanger system using the adjustment of alloy composition and alloy potential, characterized in that it further comprises the above.

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