JPS61172690A - Heat exchanger fin material and its production - Google Patents

Abstract

PURPOSE:To reduce the weight of a product and to improve corrosion resistance by forming a specific weight % of an alloy layer of Zn on the surface of a Cu base plate as a fin material. CONSTITUTION:Zn or Zn alloy is coated by an electroplating mechanical cladding method, etc. on the Cu alloy plate consisting of Cu-Zn, Cu-Cr, etc. having high conductivity. The base plate is then heated to the diffusion temp. of Zn or above to diffuse the Zn on the surface of the base plate or the base plate is passed through the inside of the vapor of the Zn to coat the Zn on the surface of the base plate and to diffuze the Zn into the surface layer of the base plate. The base plate is further subjected to rolling and tempering to form >=1% Zn alloy layer on the surface. The corrosion resistance of the fin material is improved by the formation of the surface layer of the Zn and the reduction in the weight of the product is made possible by the reduced thickness.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a heat exchanger fin material and a method for manufacturing the same, and in particular, it is possible to improve corrosion resistance and thin the fin without reducing the heat conductivity of the fin. It is especially suitable for heat exchangers used in highly corrosive environments such as automobiles.

[Conventional technology]

Heat dissipation fins used in shell-and-tube heat exchangers are required to have heat conductivity, strength, and corrosion resistance.

For example, radiators for engine cooling and heaters for air conditioning are used as heat exchangers for automobiles, and both use a copper core with fins installed between multiple tubes through which a heat exchange medium flows. A tank is attached to both ends of the tank via seat plates. For example, in a radiator, as shown in Fig. 1, a core (3) is constructed by installing full-gate fins (2) between a plurality of vertical tubes (1) through which a heat exchange medium flows. ) tube〈1) Seating plates (4a) and (4b) are provided at both ends,
Tank (5a) on the corresponding seat plate (4a), (4b)
, (5b) is installed. In the figure (6),
(7) indicates an inlet/outlet for refluxing the heat medium, and (8) and (9) indicate inlets/outlets for the heat exchange medium.

The CU type cocoa of such a radiator usually uses a tube made of brass and a corrugated fin made of Cu or Cu alloy, and the fin is attached between the tubes by soldering to heat the core. The fins have a thickness of 0.025 to 0.
060#Il Cu or Cu alloy strip is used, and small amounts of Sn, Ag, Cd, P, etc. are added to improve strength and heat resistance within a range that does not reduce heat conductivity.

In addition, radiators using CLI cores are painted black for anti-glare purposes, but this treatment is limited to the outer surface of the radiator, and the thickness is less than 10 μm, and thicker coatings are applied to the fins. harmful to heat dissipation.

[Problems to be solved by the invention] In recent years, large amounts of chlorides such as NaCl2 have been sprayed on roads for the purpose of melting snow, etc., and corrosion of car bodies due to these chlorides has become a serious issue, and radiator In automobile heat exchangers such as air conditioners and air conditioners, the fins are subject to severe wear and tear, causing a reduction in heat dissipation. For this reason, it has been considered to use a corrosion-resistant alloy such as a Cu--Ni alloy for the fins, but the heat conductivity is low, and in order to obtain the desired performance, it is necessary to increase the thickness, leading to increased cost and weight. Further, thickening of conventional materials in anticipation of corrosion or coating for anti-corrosion results in similar results and cannot be put to practical use.

On the other hand, from the standpoint of energy conservation, it is desired that automobiles be made lighter.
Although it is desired to reduce the weight of a heat exchanger, which is a component of an automobile, it has been technically difficult to simultaneously satisfy the requirements for preventing salt damage and reducing weight.

[Means for solving problems]

In view of this, as a result of various studies, the present invention has excellent corrosion resistance that can withstand the above-mentioned harsh environments for a long period of time, sufficient heat conductivity, and is resistant to corrosion and wear even when thinned to reduce weight. We have developed a heat exchanger fin material that can exhibit heat dissipation properties over a long period of time, and a method for manufacturing it.

That is, the fin material of the present invention has Zn1w on the surface of the Cu-based substrate.
It is characterized by forming an alloy layer of t% or more.

In addition, the manufacturing method of the present invention provides Zn or Zn on the surface of the Cu-based substrate.
It is characterized in that an alloy layer containing 1 wt % or more of Zn is formed on the surface by coating the alloy and then thermally diffusing Zn, or by performing rolling tempering after the thermal diffusion.

In addition to pure Cu, Cu-Zn is used as the Cu-based substrate.

Cu-Cr, Cu-Ao, Cu-8n
, Cu-Cd, Cu-Pb-8
n, Cu-In, Cu-■e
A dilute copper alloy plate with high electrical conductivity (high thermal conductivity) that can improve strength due to the alloy effect, such as a dilute copper alloy plate with an electrical conductivity of 85% lAC3 or more, preferably 90 to 98% lAC3
Zn or Zn is coated on these substrates using highly conductive alloy plates.
Alloys, such as pure Zn or Cu-Zn, Zn-8
n, ln-Cd.

Zn-Ni, Zn-Fe, Zn-Ply
, Zn-Bi-Pb, Zn-Ni-Co, and other alloys are coated by electroplating, hot-dipping, PVD, mechanical or rad methods, etc., and this is heated to a temperature higher than the Zn diffusion temperature to diffuse Zn onto the substrate surface. Alternatively, the substrate may be passed through Zn vapor to coat the surface of the substrate with Zn and simultaneously diffuse it into the surface layer of the substrate. If necessary, this is subjected to heat treatment such as rolling and annealing to finish it to the desired dimensions, and an alloy layer containing Zn of 1wt% or more, preferably 3wt% or more is formed on the surface, and the thickness of the alloy layer is 5μm. It is desirable to set the above.

Usually the fin material has a thickness of 0.05 to 0.025. Since the Zn diffusion layer is used as a strip material, it is preferable to form the above-mentioned Zn diffusion layer on a substrate with a thickness of about 1.0 mm, and then perform heat treatment such as rolling and annealing to obtain a desired size.

[For production]

The fin material of the present invention improves corrosion resistance under the above-mentioned salt damage conditions by forming an alloy layer containing Zn1wt% or more on the surface of a Qu-based substrate, and has high conductivity (high heat conductivity) due to the core made of an alloy containing Zn1wt% or less. ), this made it possible to take measures against salt damage and make the jar lighter.

In other words, it was experimentally found that the addition of Zn to Cu is effective in preventing salt damage corrosion. Demonstrates corrosion resistance.

Although the exact action and mechanism of Zn is unknown, it is thought that the Zn component selectively stops the attack of chlorine on CIJ.

On the other hand, it is known that the addition of Zn to Cu lowers the electrical conductivity of Cu, especially when Zn is dissolved in solid solution.
, 3 wt% decreases to around 10% lAC3. Therefore, if an attempt is made to obtain the desired corrosion resistance simply by adding Zn, the conductivity (thermal conductivity) will decrease, making it unsuitable for fins. Therefore, the present invention provides Zn1 on the surface of a Cu-based substrate.
wt%, preferably 3 wt% or more, is formed to a thickness of 5 μm or more to improve corrosion resistance under the salt damage conditions, and to prevent a decrease in electrical conductivity by limiting the alloy layer with a high Zn content to the surface layer. This is what I did. Furthermore, in the material of the present invention, since the surface alloy layer is generally anodic compared to the lower alloy layer, especially the Cu alloy in the core, pitting corrosion that penetrates the core is less likely to occur, and the fins are Strength reduction can be effectively suppressed.

Further, the fin material of the present invention can be coated with industrially simple methods such as electroplating, hot-deep coating, PVD, II mechanical hybridization, etc., and a Zn spreading layer can be formed on the surface thereof by thermal diffusion. In particular, electroplating provides a uniform coating of Zn or Zn alloy with a precise thickness. Further, in order to form an alloy layer with a predetermined thickness, heat treatment may be performed at a temperature of 250 to 100°C or higher. In addition, C in ln steam at 500°C or higher
By using the LI-based substrate, Zn coating and its diffusion can be carried out all at once.

[Example (1)] Using a heat-resistant CIJ strip (conductivity 95.9% IAC8) containing 6 wt% QdO,O with a thickness of 0.07 s, Zn was added to the strip using the bath shown in Table 1. After electroplating to the thickness shown in Table 1, this was subjected to a diffusion treatment under the conditions shown in Table 1, and then rolled to obtain a fin material having a thickness of 0.038 as+.

The electrical conductivity of these fins was measured, and the cross section was analyzed using an X-ray microanalyzer to analyze the surface and 70 minutes at a depth of 5 μm below the surface. In addition, the following corrosion test was conducted, and the average amount of corrosion was determined by gravimetric method.
Furthermore, a tensile test was conducted on the fins before and after corrosion to determine the rate of strength reduction due to corrosion. Simply convert these results into Zn
Table 1 shows a comparison between the plated heat-resistant 01 strip and the untreated heat-resistant 01 strip.

Plating bath NaCN 50g/I Zn (CN)2 709/J2NaO8100
g/J! Bath temperature 30℃Current density
3 A/de2 corrosion test: Salt water spray based on JIS Z2371 for 1 hour,
After that, it was placed in a constant temperature and humidity chamber at 60℃ and 95% at 23:00.
This was repeated 30 times.

As is clear from Table 1, the average amount of corrosion for Zn plated fins 11Q4 and untreated fins in order 5 is 8 to 9μ? FL(
(one side), the strength reduction rate was around 85%, that is, it became almost tattered. On the other hand, it can be seen that fins 1 and 2 of the present invention, in which an alloy layer containing 1 wt % or more of Zn was formed on the surface, suffered only slight corrosion deterioration. In particular, the reason why the amount of corrosion and the rate of decrease in strength are small is that pitting corrosion, which greatly affects strength deterioration, is stopped by the diffusion of Zn in the surface layer.

On the other hand, in fin NQ3, in which the Zn content in the alloy layer at a depth of 5 μm in the surface layer is less than 1 wt%, the amount of corrosion and the rate of decrease in strength are lower than those of NQ1.
- It is inferior to 2, and it can be seen that the improvement is insufficient under severe conditions.

[Example (2)] Using the following plating bath instead of Zn plating in Example (1), Z-low Swt%Ni alloy and Zn-10wt%Cd alloy were electroplated to the thickness shown in Table 2, This is the second
After diffusion treatment under the conditions shown in the table, it is rolled to a thickness of 0.
The fin material was 038am+. Examples of this (
A test similar to 1) was carried out, and the results were simply compared to Zn-sw.
A comparison was made with fin materials plated with t%N1 alloy and Zn-10wt%Cd alloy.

Zn-5wt%Ni alloy plating bath Zn5O+ 759/12Ni S
o 10 609/, eCH5COONa
209/A H5BOs 159/, e pH3 bath Waterfall 45℃ current density
7.5A/di2Zn-10wt%Cd alloy plating bath Zn (CN)2 76SF/lCd0
49/l NaCN 45g/l NaO880g/l! Bath temperature 35℃ Current density
2A/d■2 As is clear from Table 2, Zn-5wt%Ni alloy and Z
It can be seen that the fins IIQ6 to IIQ7 of the present invention, which were plated with n-10wt% Cd alloy and then subjected to diffusion treatment to form an alloy layer containing 1wt% or more Zn on the surface, suffered only slight corrosion deterioration. On the other hand, even if the surface 70 minutes is 1wt5 or more, 5
When the fin Nα8 is less than 1% in the μ part, the corrosion resistance is improved6.
, 7, it can be seen that it is insufficient under severe usage conditions.

(Example (3)) Using a heat-resistant 00 strip (conductivity 98% IAC8) containing 0.06 m thick A O0909wt%, the strip was heated at H2
Zn diffusion treatment was performed by exposing the material to a molten Zn bath at 590° C. for 15 seconds in an atmosphere, which also served as intermediate annealing. This was rolled to a thickness of 0.035 mm to obtain a fin material. Regarding this, the same tests as in the examples were conducted, and the results are shown in Table 3 in comparison with the fins in which the above treatment was omitted.

Shocking Laj! As is clear from Table 3, the corrosion resistance of the fins of the present invention is significantly improved compared to untreated fins.

〔Effect of the invention〕

As described above, the fins of the present invention have excellent corrosion resistance and heat conductivity, do not lose their function as fins for a long period of time even in harsh environments, and can be made thin and lightweight, making them particularly suitable for use in automobile heat exchangers. This has significant industrial effects, including not only weight reduction but also improved service life.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of an automobile radiator. 1... Tube 2... Fin 3... Core 4a, 4b... Seat plate 5a, 5b... Tank

Claims (5)

[Claims] (1) A heat exchanger fin material characterized in that an alloy layer containing 1wt% or more of Zn is formed on the surface of a Cu-based substrate. (2) The fin material for a heat exchanger according to claim 1, wherein the thickness of the alloy layer containing 1 wt % or more of Zn is 5 μm or more. (3) The surface of the Cu-based substrate is coated with Zn or a Zn alloy and then the Zn is thermally diffused, or after the thermal diffusion, rolling tempering is performed to form an alloy layer containing 1 wt% or more of Zn on the surface. A method for manufacturing heat exchanger fin material. (4) The method for manufacturing a heat exchanger fin material according to claim 3, wherein Zn or Zn alloy is coated by electroplating and then subjected to heat diffusion treatment. (5) A method for manufacturing a heat exchanger fin material according to claim 3, in which a Cu-based substrate is passed through Zn vapor to coat Zn and simultaneously perform thermal diffusion.