WO2018216832A1 - Highly corrosion-resistant heat exchanger system using control of alloy composition and alloy potential - Google Patents

Abstract

The present invention relates to the improvement of corrosion resistance of a tube, a pin, and a header, which are heat exchanger parts and are made of an aluminum material, wherein: one or more tubes, one or more headers, one or more brazing header clads, one or more fins (or heat dissipation plates), and one or more brazing pin clads are made of an aluminum alloy material; the corrosion potential of the tubes is -950 mV to 650 mV; the corrosion potential of the headers is 0-150 mV on the basis of the corrosion potential of the tubes; the corrosion potential of the header clads is 20-100 mV on the basis of the corrosion potential of the tubes; the Cu content of the aluminum alloy is 0.001-0.50 wt%; the Zn content of the aluminum alloy is 0.001-5.00 wt%; and the tubes, the headers, and the fins are joined by a brazing process using a header clad material and a fin clad material.

Description

High corrosion resistance heat exchanger system using control of alloy composition and alloy potential

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heat exchanger systems, and more particularly to improved corrosion resistance of tubes, fins and headers made of aluminum, which are heat exchanger components. In particular, it relates to the improvement of corrosion resistance by the proper selection of corrosion potential by part and the addition of special elements.

In general, aluminum or an aluminum alloy material having good light weight and thermal conductivity is used for heat exchangers such as an evaporator, a condenser, and a pipe. In these heat exchangers, it consists of a condenser tube, fin (or heat sink), a header pipe, and various piping of an aluminum alloy extrusion material. These heat exchangers are generally constructed by brazing and joining tubes and fins (generally coated with cladding plates on a fin core material or cladding) in a predetermined structure, and then brazing in a heating furnace in an inert gas atmosphere. Is completed.

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

Since the extruded tube and the pipe of the heat exchanger are used as the refrigerant passage pipe, when penetration occurs due to corrosion during use, the refrigerant leaks and cannot function as a heat exchanger. For this reason, conventionally, Zn (zinc) is affixed on the surface of an extrusion tube by spraying etc., and Zn is diffused by brazing (brazing). As a result, the Zn diffusion layer formed on the tube surface layer acts as a sacrificial anode to the core portion, thereby suppressing corrosion in the plate thickness direction and extending the corrosion penetration life. In this case, after extruded, the tube requires a process for attaching Zn of a Zn coating (sprayed or the like), resulting in an increase in manufacturing cost.

In particular, from the viewpoint of corrosion resistance of the tube, Japanese Patent Laid-Open No. 11-21649 discloses 0.15 to 0.35% by weight of iron, 0.15% by weight or less of silicon, less than 0.03% by weight of zinc, 0.55% by weight of copper, and 0.02 to 0.05% by weight of zirconium. An aluminum alloy containing 0.003 to 0.010% by weight of titanium, iron / silicon ≧ 2.5, and the remainder of which is inevitably added with aluminum has been proposed.

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

In order to improve this, Korean Patent Laid-Open Publication No. 10-2011-0072237 has proposed a method of omitting the Zn spraying process outside the tube by adding Zr and B to an aluminum alloy containing 0.15 to 0.45% of copper. . This document contains the technical idea that due to the addition effect of Zr or B, the crystals of aluminum alloys become finer and corrosion resistance is increased. However, when the copper content is more than 0.1% by weight, copper precipitates at the grain boundary during heat exchanger operation, and as a result, the sensitivity of grain boundary corrosion is increased, resulting in tube grain boundary corrosion, which shortens the corrosion penetration life of the tube. .

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

Then, in Korean Patent Laid-Open Publication No. 10-2014-0000406 due to the disadvantage of the addition of Cu to minimize the copper (Cu) to 0.01% or less, 0.50 to 1.0% by weight of manganese (Mn) and 0.2% by weight Zirconium (Zr) was added in the composition of silicon (Si) below 0.05 to 0.15% by weight, but the corrosion potential of Cu is sacrificed due to the removal of Cu and the potential by contact when assembling each part of the heat exchanger The design has been limited, making it difficult to adopt in heat exchanger systems.

Therefore, in the present invention, to compensate for the shortcomings of the prior art, to apply the cathodic protection principle to the individual parts of the heat exchanger to maximize the corrosion resistance.

An object of the present invention for the above problems, to solve the above problems in order to improve the corrosion resistance of the heat exchanger. An object of the present invention is to improve the corrosion resistance to maintain the airtightness of the heat exchanger even in harsh environments to prevent the leakage of refrigerant to extend the life of the heat exchanger system.

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), one or more brazing fins Clads;

       The corrosion potential of the tube ranges from -950 mV to 650 mV;

       The corrosion potential of the header ranges from 0 mV to +150 mV based on the corrosion potential of the tube;

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

        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;

        The tube, header and fins are joined by a brazing process by the header cladding material and the pin cladding material, which is achieved by a high corrosion resistance heat exchanger system utilizing control of alloy composition and alloy potential.

According to a feature of the invention,

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

According to another feature of the invention,

      Corrosion potential of the pin clad material may be in the range of 40mV ~ + 80mV based on the corrosion potential of the tube.

According to another feature of the invention,

The aluminum alloy may be one or more content change selected from Cu, Zn, Mn, Si, Fe, or Mg is a control factor of the main corrosion potential.

According to another feature of the invention,

The aluminum alloy may contain at least one selected from the rare earth metals of atomic number 57 (La) to 71 (Lu) in the range of 0.005 to 1.00% by weight.

According to another feature of the invention,

The aluminum alloy may contain at least 0.005% to 0.25% by weight of one or more selected from Zr and B.

According to another feature of the invention,

The process of any one of age hardening, zinc coating, chemical 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,

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

       Zn content is 0.001 to 5.00 wt%;

       The content of at least one selected from Zr and B is 0.001 to 0.25 wt%;

       The at least one content selected from the rare earth metals (atoms 57 (La) to 71 (Lu)) is 0.001 to 1.00% by weight;

       S% in the following formula is 0.05 ~ 0.30% by weight;

Is achieved by a highly corrosion resistant heat exchanger system using a control of alloy composition and alloy potential, characterized in that it comprises a tube made of an aluminum alloy material which satisfies (wherein the range of M in the formula below is 1 to 5). .

    (Equation)

    Z% = one or more contents selected from Zr, B,

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

    S% = ((R% / M) + Z%)

here,

      Content of said Cu is 0.001-0.12 weight%;

      The content of Zn is 0.001 to 3.00 wt%;

      Content of the said Fe is 0.001-0.25 weight%;

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

       At least one content selected from Zr and B may include a tube made of an aluminum alloy material containing 0.01 to 0.07% by weight.

According to another feature of the invention,

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

According to another feature of the invention,

The aluminum alloy is selected from Mn, Mg, Si, Fe, Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Sc, Nb, Hf, or Y It may further include the above.

According to the present invention, in the aluminum alloy used in the heat exchanger, it is possible to improve the corrosion resistance by adjusting the corrosion potential for each individual part to improve the 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. This results in simplification and cost reduction of the manufacturing process due to increased component life, elimination of zinc coating and the elimination of additional post-treatment processes.

1 is a diagram showing a preferred corrosion potential distribution of heat exchanger tubes, fins, headers and clads according to the present invention.

Figure 2 is a diagram showing a more preferred corrosion potential distribution of the heat exchanger tube, fins, 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, with reference to the accompanying drawings will be described with respect to the selection and system configuration of the heat exchanger material according to the present invention. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments and configurations described herein are only the most preferred embodiments of the present invention, and do not represent all of the technical ideas of the present invention, and various equivalents and modifications that may substitute them at the time of the present application may be made. It should be understood that there may be

The heat exchanger system (1) generally has a supporting structure and includes a pipe-shaped header (3), and a plurality of tubes (5) which are pipes thinner than the header (3) by connecting the headers (3) to each other; , A fin (or heat sink) 7 interposed between the tubes 5 to increase the heat transfer rate. Fins 7 may be provided in corrugated form to increase the heat exchange area as shown. The heat medium can communicate between the header 3 and the tube 5. And the header 3 and the tube 5 and the tube 5 and the pin 7 may be joined by brazing, respectively. (Hereinafter referred to as "pin" means that the heat sink is included in the present invention.)

When the aluminum tube 5 is corroded in the heat exchanger system 1, the refrigerant flows out and ends its life. Since aluminum alloys are sensitive to pitting corrosion, much effort has been made to prevent them. First, as a method of controlling the alloy composition, the content of Si, Fe and Cu, which form precipitates having a high corrosion potential, that is, local cathodes, such as Si, FeAl ₃ , Cu, CuAl ₂ , and the like, is combined with Si and Fe. There is a method of alloying Mn or Mg to form a phase with low potential. As a heat treatment method, there is a method of avoiding heat treatment in the vicinity of 500 ° C. where many precipitates acting as a cathode are generated.

A macroscopic approach is cathode protection, in which the material to be protected is higher in corrosion potential than other contact materials. In the present invention, a cathode method and a method of controlling an alloy composition are used in combination.

The effects of Cu, Zn, Mn, Fe, Si, Mg on the alloy properties are as follows.

① Cu

The alloying element Cu has a disadvantage in that the solid solution in the matrix (Matrix) increases the strength of the aluminum alloy, but greatly reduces the extrudability compared to Mn. The addition of Cu is known to increase the corrosion potential. In the case where Zn and Cu coexist, in particular, when the Zn content is small, the potential raising effect by Cu is predominant. That is, when there is much Cu content, the electric potential raising effect by Cu becomes more preferable than the electric potential lowering effect by Zn. If 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 is more than 0.45% by weight, the extrudability and corrosion resistance are simultaneously reduced (where the content is a percentage of the total weight of the aluminum alloy. All content indications in the description and claims of the invention are also the same). If the Cu content is higher than the proper content, precipitates tend to form at the grain boundaries, thereby increasing sensitivity to grain boundary corrosion and local corrosion.

② Zn

       Alloy element Zn coexists with Mg to improve mechanical properties. In general, the addition of Zn lowers the corrosion potential, but the change in corrosion potential is smaller than that of Cu.

③ Mn

Alloying element Mn increases the strength of the aluminum alloy. If the Mn content is less than 0.5% by weight, the effect of increasing strength is small, and if it exceeds 1.2 to 1.7% by weight, the extrudability is lowered. The addition of Mn is significantly smaller in the extrudability, in particular the decrease in the limit extrusion speed, compared with the case where the same amount of Si, Cu or Mg is added. It also has the effect of increasing the corrosion potential of the alloy by precipitating with a fine intermetallic compound of Al ₆ Mn. If the content is less than 0.6% by weight, the effect of adding manganese, such as corrosion resistance is less. In addition, there is an effect of eliminating the bad effect of Fe addition and grain refinement effect, and to form a compound that does not impair the corrosion resistance. Therefore, the strength can be improved without reducing the corrosion resistance. However, care should be taken because excess manganese can lower the mechanical strength of aluminum alloys.

       ④ Fe

        Alloying element Fe is an element which precipitates as an intermetallic compound in Al alloy and improves abrasion resistance. If the content is less than 0.1wt%, there is little abrasion resistance effect, and if the content exceeds 0.3wt%, the particles are coarsened and workability is poor.

In addition, even in a very small amount of Al ₃ Fe compound, and combines with Si to form an Al-Fe-Si intermetallic compound is a deterioration factor of the mechanical properties. Even small amounts of surface gloss deteriorate, making the corrosion resistance and ductility weak. In addition, recrystallization coarsening is prevented, there is a grain refinement effect. When Fe is added in an amount of 0.5 wt% or less in the die casting process, there is an effect of preventing sintering in the mold.

⑤ Si

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

⑥ Mg

The alloying element Mg increases the strength by solid solution strengthening in the matrix, but decreases the extrudability as the amount is increased. If the amount is more than 2.0% by weight, a compound having a high melting point is formed due to the flux and the reaction and the like, which tends to significantly reduce the bonding property in the brazing process. In addition, when the content exceeds 3.5% by weight, Mg ₂ Al ₃ is precipitated to increase the susceptibility to grain boundary corrosion and stress corrosion.

In addition, aging reinforcement may occur depending on whether Si and Zn coexist. Excellent machinability, especially corrosion resistance against seawater and shrinkage during solidification. In addition, the fluidity of the molten metal is weakened, and in particular, the bonding force with oxygen is strong, so care must be taken in the inflow of oxides.

The composition of the aluminum alloy for the heat exchanger can be appropriately selected in consideration of the effects on the characteristics of the main alloying elements and the corrosion resistance. Widely used alloys in heat exchangers are A 1XXX series and A 3XXX series alloys. Table 1 below shows the composition of typical alloy types.

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

In general 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% by weight depending on the copper content. Therefore, neglecting the influence of other alloying elements, the corrosion potential can be easily changed by adding or decreasing a small amount of copper in an aluminum alloy. In addition, in the case of zinc, since the corrosion potential decreases by about 30 to 40 mV as 1.0 wt% is increased in the general aluminum alloy, the change range is smaller than that of Cu. Therefore, it is possible to further control the corrosion potential 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, the corrosion potential of the aluminum alloy can be easily changed by changing the content of the alloying elements, such as Cu, Zn, Mn, Si, Mg, Fe.

For example, by adjusting the copper content and the zinc content of 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 content of Zn is preferably 5.0% by weight or less, and the content of Cu is preferably 0.5% by weight or less. Therefore, in the case of the tube, since the Cu content is preferably 0.5% by weight or less, the corrosion potential of the tube is preferably in the range of 950 to 650 mV, and more preferably in the range of 850 to 650 mV.

On the other hand, as described above, there is a cathode method as a method of preventing penetration of the tube. At this time, a suitable component as a sacrificial anode is a pin. This is because the fins do not have to worry about leakage of the refrigerant even if the through corrosion occurs. Therefore, in order to cathode the tube, the corrosion potential of the fin should be lower than that of the tube, and the range is preferably in the range of -20 mV to -170 mV, and more preferably in the range of -20 mV to -100 mV. If the difference is too small, the effect of the cathode method is insignificant, and if it is too large, the corrosion rate of the pin is too large. Therefore, when the fin material is A3003, the corrosion potential decreases when the copper content is decreased or the zinc content is increased. Thus, for example, a tube with the copper potential increased by adding copper based on the A3003 material. Combining the pins with the addition of zinc to lower the corrosion potential improves the corrosion resistance of the tube.

Also, a portion where the refrigerant of the heat exchanger is easily leaked due to corrosion is a junction between the tube 5 and the header 3. In particular, although the through corrosion of the header 3 does not occur, even if the header 3 is partially corroded in the vertical direction of the contact surface with the tube at the tube / header junction, leakage occurs, so pay attention to the corrosion potential of the header 3. You should pay attention. On the contrary, since the tube 5 has a constant tube thickness in the depth direction of the joint, leakage of the refrigerant is prevented until the entire thickness thereof is penetrated. Therefore, since the corrosion resistance of the header 3 needs to be strengthened 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.

The heat exchanger system 1 also typically assembles the tubes 5, fins 7 and headers 3 and then joins the parts by brazing, for which purpose the cladding for brazing outside the fin core (fin clad) aluminum alloy is bonded. In the case of the header 3, the cladding material is present at the site where the tube 5 is coupled. This clad material is melted in the brazing process and serves to join the parts. In the case of tube / pin and tube / header junctions, it is desirable to have high resistance to corrosion for electrical contact retention and structural stability.

In the case of the cladding material of the tube / fin, the corrosion potential of the fin 7 is low, and therefore, the range of -40 to +80 mV is preferable, and the range of +0 to +80 mV is more preferable than the corrosion potential of the tube 5. In the case of the cladding material of the tube / header, since the corrosion potential of the header 3 is high, it is preferable that it is rather high compared with the cladding material of the tube / pin. 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 the region of the preferred corrosion potential of the fin 7 and the header 3 and the clad material around the tube 5, and FIG. 2 shows the region of the more preferred corrosion potential.

On the other hand, as a method of alleviating the through corrosion of the tube (5) can be achieved by the addition of the following alloying elements.

      ⑦ Zr (zirconium) and B (boron)

Zirconium (Zr) not only improves the strength by miniaturizing the size of the crystal grains, but also has the effect of suppressing the generation of locally occurring pitting corrosion by finely dispersing precipitates that generate a potential difference. This has the characteristic of inducing corrosion to occur uniformly over the whole area. In addition, the deformation resistance of the extrusion process is reduced to improve the extrusion characteristics, and at the same time, to suppress the grain coarsening after brazing, thereby improving the strength. It is not effective at 0.005 wt% or less, and 0.25 wt% or less is preferable because of the difficulty of extrusion and economical cost increase. Boron has a similar effect to zirconium when added to aluminum alloys.

       ⑧ Rare Earth metal (RE)

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

Rare earth metals of atomic number 57 (La) to 71 (Lu) mitigate local corrosion by reducing the local corrosion cathodic reaction due to precipitates precipitated in the matrix, and consequently reducing local corrosion To act. In addition, to reduce the components of Fe, Ni, etc., which are fragile corrosion resistance elements present in the molten metal during the manufacture of aluminum to enhance the corrosion resistance. Therefore, even when the impurity concentration such as Fe is more than 0.2% by weight, it helps to maintain corrosion resistance.

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

In addition, by improving the ductility and adhesion of the oxide film formed at the grain boundary or the surface, the lifetime of the oxide film is extended to improve corrosion resistance. In addition, by increasing the strength and fluidity of the aluminum alloy to improve the plastic workability of the metal, there is an effect to improve the brazing properties.

       Corrosion resistance improvement effect of the rare earth metal is about 20% to 100% compared to the effect of Zr, so a similar effect can be realized with a dose of 1 to 5 times that of Zr. This can be a useful means to replace high priced Zr.

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

Because of its beneficial properties, many rare earth metals have been researched and developed, but the development activities are mainly due to the increase of corrosion resistance of magnesium (alloy), the strength increase of some aluminum alloys for casting, and the conversion coating of aluminum alloy surface. The focus has been on increasing corrosion resistance.

However, to date, it is difficult to find related literatures in which rare earth elements are added directly to alloys to improve the corrosion resistance of the 1XXX, 3XXX and 6XXX series and the 4XXX series for brazing.

       However, in very few documents, records can be found for the A 1XXX series and the A 4XXX series. The documents are disclosed in Korean Patent Registration No. 10-1335680, Korean Patent Registration No. 10-1349359 and Korean Patent Registration No. 10-1194970, but the contents are different from the present invention.

      ⑨ Other Elements

In all the above cases, aluminum alloys contain alloying elements (Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Y) that are widely used in the aluminum industry and inevitable impurities. In addition, it may further include.

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

(Actual example)

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

In the present invention, the composition (% by weight) of the aluminum alloy according to one preferred embodiment may be as shown in Table 2 below. These alloys have specifications for the widely used A 3003 and A 4343 alloy compositions, and each alloy may contain additional unavoidable impurities.

Alloy class	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 A 3003 was the basic material of the tube, the pin and the header (alloy symbol b) and the cladding material for the brazing was A4343 as the base material (alloy symbol h). In the case of A3003, the alloy with high corrosion potential by adding copper is indicated by the high corrosion potential 1 (alloy symbol a) of Table 3, and the alloy with low corrosion potential by adding zinc is low corrosion potential 1 (alloy symbol c) of Table 3 ).

       In addition, based on the alloy symbol b, an alloy containing La, which is a rare earth metal, was designated as an improved alloy 1 (alloy symbol d), and an alloy containing Zr was designated as an improved alloy 2 (alloy symbol e). The alloy to which Zr was added at the same time is referred to as improved alloy 3 (alloy symbol f). In addition, an alloy with an increased copper corrosion potential in the cladding alloy symbol h is indicated as a high corrosion potential 2 (alloy symbol g), and an alloy having a reduced copper potential by reducing copper has a low corrosion potential 2 (alloy symbol). i).

Alloy class	Corrosion potential	Alloy sign	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
Base 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 heat exchanger by selecting the type of aluminum alloy prepared as a tube, fin, header and clad material. For example, in the case of Sample No. 1, the material of the tube, the pin and the header is selected by the alloy symbol b and the clad material is selected by the h. A total of 12 samples were made of 3 sets each.

In order to evaluate the corrosion resistance of the heat exchanger system, SWAAT evaluation according to ASTM standard was performed and the results are shown in Table 4. In this case, the numerical values were expressed as the average of three sets. SWAAT evaluation was a test according to ASTM standard G85 was added to the glacial Acetic acid to 4.2% by weight of NaCl solution to maintain a pH of 2.8 to 3.0 to perform a test spraying at 0.07MPa pressure under a temperature atmosphere of 49 ℃. At this time, the spray amount was maintained at 1-2 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 Symbols	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 Symbols	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, when the same clad material (alloy symbol h) is used and the corrosion potential of the tube 5, the fin 7 and the header 3 is changed (samples 1 to 7), Sample number 5 shows the best corrosion resistance. This is the case when the order of corrosion potential is header> tube> pin. 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 metals and zirconium was performed. It shows that it strengthens. In the case of Sample Nos. 10 to 12, the corrosion potential of the cladding material was changed based on Sample No. 10. It has been shown that when the potential of the clad material is lower than the tube (sample no. 12), the corrosion resistance is weakened.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

Claims (11)

1.        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), one or more brazing fins Clads;

          The corrosion potential of the tube ranges from -950 mV to 650 mV;

          The corrosion potential of the header ranges from 0 mV to +150 mV based on the corrosion potential of the tube;

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

           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;

           And the tube, the header and the fin are joined by the header cladding material and the pin cladding material in a brazing process.
2.        The method of claim 1,

          Corrosion potential of the fin (or heat sink) is characterized in that the range of 20mV ~ -170mV based on the corrosion potential of the tube, high corrosion resistance heat exchanger system using the control of the alloy composition and alloy potential.
3.        The method of claim 1,

          Corrosion potential of the pin clad material is characterized in that the range of 40mV ~ + 80mV based on the corrosion potential of the tube, high corrosion resistance heat exchanger system using the control of the alloy composition and alloy potential.
4. The method of claim 1,

   The aluminum alloy is characterized in that the change in the content of one or more selected from Cu, Zn, Mn, Si, Fe, or Mg is a control factor of the main corrosion potential, high corrosion resistance heat exchanger system using the control of the alloy composition and alloy potential. .
5. The method of claim 1,

   The aluminum alloy contains at least one selected from rare earth metals of atomic number 57 (La) to 71 (Lu) in the range of 0.005 to 1.00% by weight, high corrosion resistance by controlling the alloy composition and alloy potential Heat exchanger system.
6. The method of claim 1,

   The aluminum alloy is characterized in that containing at least one selected from Zr, B of 0.005 ~ 0.25% by weight, high corrosion resistance heat exchanger system using the control of the alloy composition and alloy potential.
7. The method of claim 1,

   Alloy composition, characterized in that any one of the process of age hardening, zinc coating, chemical coating, resin coating or a combination thereof is further added to any one of the tube, fin (or heat sink), header or a combination thereof. High corrosion resistance heat exchanger system using control of alloy potential.
8.        The content of Cu is 0.001 to 0.50% by weight;

          Zn content is 0.001 to 5.00 wt%;

          The content of at least one selected from Zr and B is 0.001 to 0.25 wt%;

          The at least one content selected from the rare earth metals (atoms 57 (La) to 71 (Lu)) is 0.001 to 1.00% by weight;

          S% in the following formula is 0.05 ~ 0.30% by weight;

   A high corrosion resistance heat exchanger system using a control of an alloy composition and an alloy potential, characterized in that it comprises a tube made of an aluminum alloy material (where M in the formula below is 1 to 5).

       (Equation)

       Z% = one or more contents selected from Zr, B,

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

       S% = ((R% / M) + Z%)
9.        The method of claim 8,

          Content of Cu is 0.001-0.12 weight%;

          Zn content is 0.001 to 3.00 wt%;

          Content of Fe is 0.001-0.25 weight%;

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

          At least one content selected from Zr and B is 0.01 to 0.07 wt%; High corrosion resistance heat exchanger system using a control of the alloy composition and alloy potential, characterized in that it comprises a tube made of an aluminum alloy containing.
10. The method of claim 8,

           A high corrosion resistance heat exchanger system using a control of an alloy composition and an alloy potential, characterized in that the aluminum alloy comprises Fe in the range of 0.40 to 0.70% by weight.
11. The method according to any one of claims 1 to 8,

    The aluminum alloy is selected from Mn, Mg, Si, Fe, Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Sc, Nb, Hf, or Y The highly corrosion-resistant heat exchanger system using the adjustment of an alloy composition and alloy potential further characterized by the above.

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