KR20170116726A - Corrosion resistant heat exchanger using the control of alloy composition and potential - Google Patents

Abstract

The present invention relates to the improvement of the corrosion resistance of tubes, fins and headers made of aluminum, which are heat exchanger parts. His composition is; One or more tubes made of a luminescent alloy material, one or more headers, one or more header clades for brazing, one or more fins (or heat sinks), one or more brazing pins Clad; 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; The Cu content of the aluminum alloy is 0.001-0.50% by weight; And the Zn content of the aluminum alloy is 0.001 to 5.00 wt%, and the tube, the header and the fin are joined by the brazing material by the header clad material and the pin clad material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high corrosion resistant heat exchanger system using alloy composition and alloy potential control,

The present invention relates to a heat exchanger system and, more particularly, to improving the corrosion resistance of tubes, fins, and headers of aluminum, which are heat exchanger parts. Particularly, it concerns the selection of the corrosion potential for each part and the improvement of corrosion resistance by the addition of special elements.

For heat exchangers such as evaporators, condensers, and piping, aluminum or aluminum alloy materials, which are generally lightweight and have good thermal conductivity, are used. These heat exchangers consist of a condenser tube, a fin (or heat sink), a header pipe, and various piping of aluminum alloy extruded material. These heat exchangers are generally constructed by assembling a tube and a pin (generally a plate material for brazing to the pin core material is covered or clad) with a predetermined structure, and then brazing in a heating furnace in an inert gas atmosphere. Is completed.

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

Since the extruded tube and piping of the heat exchanger are used as the refrigerant passage pipe, leakage of the refrigerant occurs when the pipe is penetrated by corrosion during use, so that the function as the heat exchanger can not be achieved. For this reason, conventionally, Zn (zinc) is attached to the surface of the extruded tube by spraying or the like in advance, and Zn is diffused by brazing (soldering). As a result, the Zn diffusion layer formed on the surface layer of the tube acts as a sacrificial anode against the deep portion, thereby suppressing corrosion in the plate thickness direction, thereby prolonging the corrosion penetration life. In this case, Zn is required to be attached to the tube after the Zn coating (spraying, etc.) is extruded, resulting in an increase in manufacturing cost.

In particular, in view of the corrosion resistance of the tube, Japanese Patent Laid-Open No. 11-21649 discloses a steel sheet comprising 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, % Of titanium, and 0.003 to 0.010 wt% of titanium, iron / silicon ≥2.5, and the remainder being aluminum and inevitably added.

However, since copper is added as an additive element in order to secure the corrosion resistance of the alloy, a large amount of copper (0.55% by weight) is added to form a large number of Al-Cu intermetallic compounds, There is a problem that the corrosion potential is lowered in the local region of the base material (material) due to precipitation of the intermetallic compound, and the corrosion resistance characteristics are deteriorated.

To improve this, Korean Patent Laid-Open No. 10-2011-0072237 proposes a method in which Zr and B are added to an aluminum alloy containing 15 to 0.45% of copper to omit the Zn spraying process outside the tube have. The literature contains a technical idea that the crystal of the aluminum alloy becomes finer due to the effect of adding Zr or B and the corrosion resistance is increased. However, when the content of copper is 0.1 wt% or more, copper precipitates at the grain boundaries during the operation of the heat exchanger, resulting in increased susceptibility to intergranular corrosion, resulting in generation of grain boundary corrosion and shortening of the corrosion life of the tube .

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

In order to increase the corrosion resistance, copper (Cu) is minimized to 0.01% or less and 0.50 to 1.0% by weight of manganese (Mn) and 0.2% by weight of copper are added, (Zr) of 0.05 to 0.15% by weight is added to the composition of silicon (Si) below, but the advantage of increasing the corrosion potential of Cu due to the removal of Cu is sacrificed, and the potential It is difficult to adopt it in the heat exchanger system because it restricts the design.

Therefore, in order to overcome the drawbacks of the prior art, the present invention attempts to maximize the corrosion resistance by applying the cathode method principle to the individual parts of the heat exchanger.

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

An object of the present invention is to solve the above-mentioned problems in order to improve the corrosion resistance of a heat exchanger. It is an object of the present invention to improve the corrosion resistance so that the airtightness of the heat exchanger is maintained even in a harsh environment, thereby preventing the refrigerant from flowing out, thereby prolonging the life of the heat exchanger system.

The purpose of the above is; One or more tubes of aluminum alloy material, one or more headers, one or more header clades for brazing, one or more fins (or heat sinks), one or more brazing pins Clad;

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;

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

Wherein the aluminum alloy has a Zn content of 0.001 to 5.00 wt%

Wherein the tube, header and fin are joined in a brazing process by the header cladding material and the fin cladding material.

According to an aspect of the present invention,

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

According to another aspect of the present invention,

The corrosion potential of the pin clad material may range from -40 mV to +80 mV based on the corrosion potential of the tube.

According to still another aspect of the present invention,

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

According to still another aspect of the present 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 still another aspect 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% by weight.

According to still another aspect of the present invention,

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

Another object of the present invention is to provide

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

The content of Zn is 0.001 to 5.00 wt%;

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

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

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

Resistant heat exchanger system using the alloy composition and the control of the alloy potential, characterized in that it comprises a tube made of an aluminum alloy material satisfying the following formula (M in the following formula is 1 to 5) .

(Equation)

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

R% = atomic numbers 57 (La) to 71 (Lu)),

S% = ((R% / M) + Z%) Here,

The Cu content is 0.001 to 0.12% by weight;

The content of the base is 0.001 to 3.00 wt%

The Fe content is preferably 0.001-0.25 wt%

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

Zr, and B in an amount of 0.01 to 0.07% by weight;

According to still another aspect of the present invention,

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

According to still another aspect of the present invention,

The aluminum alloy may be one selected from the group consisting of Mn, Mg, Si, Fe, Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Sc, Nb, Hf, Or more.

According to the present invention, in the aluminum alloy used in the heat exchanger, corrosion resistance can be improved by adjusting the corrosion potential for each individual component in order to improve the corrosion resistance. Further, by improving the composition by adding special elements such as rare earth metals, the corrosion resistance and the strength can be further improved. As a result, it is possible to simplify the manufacturing process and reduce the cost by increasing the lifetime of the parts, omitting the zinc coating process and omitting the additional post-treatment process.

FIG. 1 is a view showing a preferable corrosion potential distribution of a heat exchanger tube, a fin, a header and a clad according to the present invention.
FIG. 2 is a view showing a more preferable corrosion potential distribution of a heat exchanger tube, a fin, a header, and a 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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a selection of a material for a heat exchanger according to the present invention and a system configuration thereof will be described with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments and configurations described in the present specification are merely the most preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Accordingly, various equivalents and variations And the like.

The heat exchanger system 1 generally has a support structure and includes a header 3 in the form of a pipe and a plurality of tubes 5 which are connected to each other by a header pipe 3 and are thinner than the header 3 And a pin (or heat sink) 7 interposed between the tubes 5 to increase the heat transfer coefficient. The fins 7 may be provided in a corrugated form to increase the heat exchange area as shown. A heating medium can 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. Denoted "pin" means that the heat sink is included in the present invention).

When the tube 5 of aluminum material is corroded in the heat exchanger system 1, the refrigerant flows out and its lifetime ends. Aluminum alloys are sensitive to pitting corrosion, so efforts have been made to prevent formulations. First, as a way through the control of the alloy composition, i.e., a high corrosion potential precipitates, lower the content of Si, Fe, and Cu for forming the like Si, FeAl _3, Cu, CuAl ₂ is the local anode, in combination with Si, Fe There is a way to alloW Mn or Mg to form a phase with a low dislocation. As a heat treatment method, there is a way to avoid heat treatment in the vicinity of 500 DEG C where many precipitates acting as a cathode are generated.

From a macroscopic point of view, there is a cathodic protection scheme to further increase the corrosion potential compared to other contact materials. In the present invention, the cathode method and the alloy composition control method are used in combination.

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

(1) Cu alloys Element Cu increases the strength of aluminum alloys by dissolving in the matrix but has a disadvantage in that the extrudability is greatly lowered compared with 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 the Cu content is large, the effect of increasing the potential by Cu is dominant rather than the effect of lowering the potential by Zn. When the content is less than 0.12% by weight, the effect of adding copper such as corrosion resistance is hardly exhibited. When the content exceeds 0.45% by weight, the extrudability and corrosion resistance are lowered at the same time. All content indications in the description and claims of the present invention are also the same). Precipitates tend to form at the grain boundaries when Cu is above the titration level, which increases susceptibility to intergranular corrosion and local corrosion.

② Zn

The alloy element Zn coexists with Mg to improve the mechanical properties. In general, when Zn is added, the corrosion potential is lowered, but the change in corrosion potential is smaller than that of Cu.

③ Mn

The alloying element Mn increases the strength of the aluminum alloy. If the Mn content is less than 0.5% by weight, the strength increase effect is small, and if the Mn content exceeds 1.2 to 1.7% by weight, the extrudability is deteriorated. The addition of n significantly reduces the extrudability, particularly the limit extrusion rate, as compared with the case where Si, Cu or Mg is added in an equal amount. It also has the effect of precipitating into a fine intermetallic compound of Al ₆ Mn to increase the corrosion potential of the alloy. When the content is less than 0.6% by weight, the effect of adding manganese, such as corrosion resistance, is small. In addition, it has an effect of eliminating the bad effect of Fe addition and an effect of grain refinement, thereby forming a compound which does not deteriorate the corrosion resistance. Therefore, the strength can be improved without deteriorating the corrosion resistance. However, excessive manganese may reduce the mechanical strength of the aluminum alloy.

④ Fe

 Alloying element Fe is an element that precipitates as an intermetallic compound in an Al alloy and improves wear resistance. When the content is less than 0.1 wt%, there is almost no wear resistance effect. When the content is more than 0.3 wt%, the particles are coarsened and the workability is poor.

In addition, the Al ₃ Fe compound is formed in a very small amount and forms an intermetallic compound of Al-Fe-Si by bonding with Si, which is a factor of deterioration of mechanical properties. The surface gloss is deteriorated even in a small amount, and the corrosion resistance and ductility are weakened. In addition, there is an effect of refining grain refinement by preventing recrystallization and coarsening. When Fe is added in an amount of 0.5% by weight or less in the die casting process, the effect of preventing sticking to the mold is prevented.

⑤ Si

The alloy element Si precipitates as an Al-Mn-Si intermetallic compound to inhibit crystal grain growth through interfering with grain boundary movement and reduce the deformation resistance upon extrusion, thereby improving the extrudability. When the content is less than 0.05% by weight, the casting cost increases. When the content is more than 0.10%, the Al-Mn-Si based intermetallic compound is formed in the alloy. This may result in a drop in corrosion potential. On the other hand, when the content exceeds 0.2% by weight, the strength of the alloy is increased and the extrudability is lowered.

⑥ Mg

Alloy 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% by weight, a compound having a high melting point is formed due to reaction with the flux or the like, so that the bonding property tends to be remarkably decreased in the brazing process. On the other hand, if it exceeds 3.5% by weight, Mg ₂ Al ₃ precipitates and becomes susceptible to grain boundary corrosion and stress corrosion.

Also, the aging strengthening characteristics may be generated depending on the coexistence of Si and Zn. The cutting workability is excellent, the corrosion resistance to seawater is particularly good, and the shrinkage rate upon coagulation is reduced. In addition, the flowability of the molten metal is weakened, and the bonding strength with oxygen is particularly strong, so care must be taken for the introduction of oxides. The composition of the aluminum alloy for the heat exchanger can be appropriately selected in consideration of the influence on the characteristics of the main alloy element and the corrosion resistance. Alloys widely used in heat exchangers are the A 1XXX series and the A 3XXX series alloys. Table 1 below shows the compositions of representative alloys.

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 alloys, the corrosion potential is most strongly influenced by Cu and the corrosion potential ranges from -950 mV to -650 mV in the range of 0.01 to 0.5% by weight, depending on the copper content. Therefore, ignoring the influence of other alloying elements, it is possible to easily change the corrosion potential by adding or reducing a small amount of copper in the aluminum alloy. In the case of zinc, since the corrosion potential is reduced by about 30 to 40 mV as the aluminum alloy is increased by 1.0 wt%, the variation of the corrosion resistance is smaller than that of Cu. Therefore, it is possible to further control the corrosion potential by the content of zinc. Mn also has an effect of increasing the corrosion potential and Si has an effect of lowering the corrosion potential. Therefore, the corrosion potential of the aluminum alloy can be easily changed by changing the content of alloying elements such as Cu, Zn, Mn, Si, Mg, and Fe. For example, the corrosion potential of the alloy can be changed by controlling the content of copper and the content of zinc in A1070 and A3003.

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

On the other hand, as described above, there is a negative electrode method as a method of preventing penetration corrosion of the tube, and a suitable part as a sacrificial anode is a pin. In the case of the pin, even if penetration corrosion occurs, the refrigerant does not leak. Therefore, in order to make the tube cathodic, the corrosion potential of the pin should be lower than the corrosion potential of the tube, and the range is preferably in the range of -20 mV to -170 mV, 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 becomes too large. Therefore, when the material of the fin is A3003, if the content of copper is decreased or the content of zinc is increased, the corrosion potential is lowered. For example, a copper tube is added to the tube of A3003 to increase the corrosion potential When zinc is added to combine the pins with lower corrosion potential, the corrosion resistance of the tube is improved. Also, the portion where the refrigerant of the heat exchanger is likely to leak due to corrosion is a junction between the tube 5 and the header 3. In particular, even though penetration corrosion of the header 3 does not occur, leakage occurs even if only a part of the header 3 is corroded in the vertical direction of the contact surface with the tube at the tube / header joint portion, so pay attention to the corrosion potential of the header 3 You have to lean. On the contrary, in the case of the tube 5, since the tube 5 has a constant tube thickness in the depth direction of the joint portion, leakage of the refrigerant is prevented until the entire thickness thereof is penetrated. Therefore, it is necessary to strengthen the corrosion resistance of the header 3 rather than the tube 5, so that the corrosion potential of the header 3 is preferably 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, the pins 7 and the headers 3 and then joins the components to the brazing. For this purpose, a brazing cladding (fin clad) aluminum alloy is bonded. Also in the case of the header 3, a clad material exists at a portion to be coupled with the tube 5. Such a clad material melts in the brazing process and serves to join the components. In the case of tube / pin and tube / header connections, it is desirable to have high resistance to corrosion for electrical contact retention and structural stability.

In the case of the clad material of the tube / pin, the corrosion potential of the pin 7 is low, so it is preferably in the range of -40 to +80 mV compared to the corrosion potential of the tube 5, more preferably in the range of +0 to +80 mV. In the case of the clad material of the tube / header, the corrosion potential of the header 3 is high, so it is preferable that it is somewhat higher than the clad material of the tube / pin. The range is preferably in the range of -20 to +100 mV with respect to the corrosion potential of the tube (5), more preferably in the range of +10 to +90 mV

  The corrosion potential relationship between these components is shown in Figs. 1 and 2. Fig. FIG. 1 is a view showing a 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 is a diagram showing a more preferable area of the corrosion potential.

On the other hand, a method for alleviating the penetration corrosion of the tube 5 can be achieved by the addition of the following alloying element.

   Zr (zirconium) and B (boron)

Zirconium (Zr) not only improves the strength of the crystal grains by reducing the size of the crystal grains, but also disperses the precipitates which cause the potential difference to suppress the occurrence of locally generated pitting corrosion. This leads to the uniform corrosion of the entire area. In addition, the deformation resistance of the extrusion processing is reduced to improve the extrusion characteristics, and the function of enhancing the strength by suppressing crystal grain coarsening after brazing. If the content is less than 0.005% by weight, there is no effect. If the content is more than 0.25% by weight, extrusion is difficult and economic cost is increased. Boron shows an effect similar 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.

The rare earth metals of atomic number 57 (La) to 71 (Lu) are effective in reducing the local anodic reaction due to precipitates precipitated in the matrix and consequently reducing the local local anodic reaction, . In addition, corrosion resistance is strengthened by reducing components such as Fe and Ni which are vulnerable to corrosion in the molten metal when manufacturing aluminum. Therefore, even when the impurity concentration of Fe or the like is 0.2 wt% or more, corrosion resistance can be maintained.

In addition, since rare earth metals have an effect of raising the corrosion potential, it is also possible to minimize Cu addition for the purpose of raising the corrosion potential or to replace Cu. Therefore, when the Cu content is increased to increase the corrosion potential, the side effect is minimized and the corrosion resistance is improved.

In addition, by improving the ductility and adhesion of the oxide film formed on the grain boundary or on the surface, the lifetime of the oxide film is extended and the corrosion resistance is improved. In addition, the strength and fluidity of the aluminum alloy are increased, thereby improving the plastic workability of the metal and improving the brazing property.

The effect of improving the corrosion resistance of rare earth metals is 20% to 100% compared with the effect of Zr, so that a similar effect can be achieved with a dosage of 1 to 5 times the Zr. This can be a useful alternative to high-priced Zr.

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

Rare earth metals are undergoing much research and development due to their beneficial properties, but their development activities are mainly in the fields of increasing the corrosion resistance of magnesium (alloys), increasing the strength of aluminum alloys for some castings, Corrosion resistance.

However, to date, there is no literature to add rare earth elements directly to alloys in order to improve the corrosion resistance of 1XXX, 3XXX and 6XXX series and 4XXX series for brazing aluminum alloys.

However, in very few documents, you can find records for the A 1XXX series and the A 4XXX series. The document is disclosed in Korean Patent No. 10-1335680, Korean Patent No. 10-1349359, and Korean Patent No. 10-1194970, but is different from the present invention.

   Other elements

In all of the above-mentioned cases, the aluminum alloys are made of alloying elements (Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Y) and inevitable impurities And may further include additional ones.

According to the present invention, zinc coating (spraying or the like) treatment is applied to any one of the tube 5, the pin 7, the header 3, or a combination thereof to obtain a sacrificial anode effect May be added, and corrosion resistance may be increased by further applying a chemical conversion coating. Further, the surface of the heat exchanger according to the present invention may be further coated with silicone or a resin coating to further improve the corrosion resistance. Further, if necessary, an additional age hardening heat treatment may be performed to increase the strength.

(Example)

Hereinafter, the present invention will be described more specifically in order to facilitate understanding of the present invention. However, the following examples are only illustrative of the present invention, and the scope of the present invention is not limited thereto.

The composition (% by weight) of the aluminum alloy according to one preferred embodiment of the present invention may be as shown in Table 2 below. This alloy is the specification of the currently widely used A 3003 alloy and A 4343 alloy composition, which may contain additional inevitable impurities in each alloy.

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 kinds of alloys used in the present invention. A 3003 is made of the base material (alloy symbol b) of the tube, the pin and the header, and the material of the clad material for brazing is A4343 (alloy symbol h). In case of A3003, alloys with increased corrosion potential by adding copper are represented by high corrosion potential 1 (alloy symbol a) in Table 3, and alloys with low corrosion potential by adding zinc have low corrosion potential 1 (alloy symbol c ).

In addition, an alloy with the base of alloy symbol b and the addition of La as a rare earth metal is indicated by the modified alloy 1 (alloy symbol d), the alloy with Zr is indicated by the improved alloy 2 (alloy symbol e) Zr at the same time is referred to as an improved alloy 3 (alloy symbol f). In addition, alloys with increased corrosion potential by increasing the copper in the alloy symbol h of the clad material are denoted by high corrosion potential 2 (alloy symbol g) and alloys with reduced corrosion potential by decreasing copper are called low corrosion potential 2 i).

Alloy type Corrosion potential Alloy symbol Zn Mn Si Cu Fe etc. La Zr  Al High corrosion potential 1 -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 potential 1 -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 potential 2 -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 potential 2 -740 i 0.10 0.05 7.5 0.15 0.45 0.15max - - Rem

Table 4 shows the results of assembling the thus-produced aluminum alloy as a material for tubes, fins, headers, and clad, and assembling it with a heat exchanger. For example, in case of Sample No. 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 prepared for each sample.

In order to evaluate the corrosion resistance of the heat exchanger system, the SWAAT evaluation according to the ASTM standard was carried out and the results are shown in Table 4. At this time, the result value is indicated by three sets of average values. The SWAAT evaluation was conducted in accordance with ASTM Standard G85, in which Glacial Acetic acid was added to a 4.2 wt% NaCl solution to maintain the pH of 2.8 to 3.0, and the test was performed at 0.07 MPa pressure under a temperature atmosphere of 49 캜. 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 the above Table 4, when the same clad material (alloy symbol h) is used and the corrosion potential of the tube 5, the pin 7 and the header 3 is changed (Samples 1 to 7) Sample No. 5 shows the best corrosion resistance. This is true when the order of the corrosion potential is header> tube> pin. In addition, in the case of Sample Nos. 8 to 10, the addition of La (Sample No. 8), Zr (Sample No. 9) and La + Zr (Sample No. 10) to the tube in Sample No. 5 and the addition of rare earth metals and zirconium As well. In case of Sample Nos. 10 to 12, the corrosion potential of the clad material was changed based on Sample No. 10. And shows that when the potential of the clad material is lower than the tube (Sample No. 12), the corrosion resistance is weakened.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

1: Heat exchanger system 3: Header
5: tube 7: fin

Claims (11)

One or more tubes of aluminum alloy material, one or more headers, one or more header clades for brazing, one or more fins (or heat sinks), one or more brazing pins Clad;
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;
The Cu content of the aluminum alloy is 0.001-0.50% by weight;
Wherein the aluminum alloy has a Zn content of 0.001 to 5.00 wt%
Wherein the tube, header and fin are joined in a brazing process by the header clad material and the pin clad material.
The method according to claim 1,
Wherein the corrosion potential of the fin (or heat sink) is in the range of -20 mV to -170 mV based on the corrosion potential of the tube.
The method according to claim 1,
Wherein the corrosion potential of the pin clad material is in the range of -40 mV to +80 mV based on the corrosion potential of the tube.
The method according to claim 1,
Wherein the aluminum alloy is a control factor of the main corrosion potential by a change in at least one selected from Cu, Zn, Mn, Si, Fe, or Mg. .
The method according to claim 1,
Wherein the aluminum alloy contains 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. Heat Exchanger System.
The method according to claim 1,
Wherein the aluminum alloy comprises at least one selected from the group consisting of Zr and B in an amount of 0.005 to 0.25% by weight based on the alloy composition and the alloy potential.
The method according to claim 1,
The process according to any one of the preceding claims, characterized in that either one of the above-mentioned tube, fin (or heat sink), header or a combination thereof is further subjected to an aging hardening heat treatment, a zinc coating, a chemical coating, a resin coating, And a high corrosion resistant heat exchanger system using control of alloy potential.
The content of Cu is 0.001-0.50% by weight;
The content of Zn is 0.001 to 5.00 wt%;
The content of at least one selected from Zr and B is 0.001 to 0.25% by weight;
The content of at least one selected from the rare earth metals (atomic number 57 (La) to 71 (Lu)) is 0.001 to 1.00% by weight;
S% in the following formula is 0.05 to 0.30 wt%;
Wherein the alloy comprises a tube made of an aluminum alloy material, wherein the range of M in the following formula is 1 to 5. The high alloy heat exchanger system according to claim 1,
(Equation)
The content of at least one selected from Z% = Zr and B,
R% = atomic numbers 57 (La) to 71 (Lu)),
S% = ((R% / M) + Z%) 9. The method of claim 8,
The content of Cu is 0.001 to 0.12% by weight;
The content of Zn is 0.001 to 3.00 wt%
The content of Fe is 0.001 to 0.25 wt%
The content of at least one selected from the rare earth metals having atomic numbers of 57 (La) to 71 (Lu) is 0.05 to 0.50% by weight;
Zr and B in an amount of 0.01 to 0.07% by weight based on the total weight of the aluminum alloy material.
9. The method of claim 8,
Wherein the aluminum alloy comprises Fe in the range of 0.40 to 0.70 weight percent. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
9. The method according to any one of claims 1 to 8,
The aluminum alloy may be one selected from the group consisting of Mn, Mg, Si, Fe, Ti, Cr, V, Ni, Co, In, Pb, Bi, Ca, Be, Ag, Pd, Sb, Sc, Nb, Hf, Further comprising the step of controlling the composition of the alloy and the alloy potential.

Images