JPH0413093A - Heat exchanger made of aluminum, seldom causing separation of fin - Google Patents

Abstract

PURPOSE:To obtain a heat exchanger made of aluminum, which is seldom causing the separation of fins and capable of retaining excellent heat exchanging performance for a long period of time, by a method wherein a tube and fins are connected through a brazing material layer, generated by heating them after applying connecting slurry having principal constituents of zinc chloride, copper compound and solvent and constituted of the principal constituents of zinc and copper. CONSTITUTION:Tubes 2, corrugate fins 3 and coupling members 4 made of aluminum are assembled and, thereafter, the assembly is dipped into connecting slurry consisting of zinc chloride, copper chloride and solvent. Subsequently, the assembly is taken out of the slurry and, thereafter, is heated by a gas burner while the heat exchanger is manufactured by washing the assembly with water after finishing the heating to remove remaining slurry. The tubes and the fins are connected through the brazing material layer consisting of the principal constituents of zinc and copper generated by heating after applying the connecting slurry in such a manner whereby the heat exchanger seldom causes the separation of fins and is capable of retaining excellent heat exchanging performance for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an aluminum heat exchanger that is used in, for example, condensers, evaporators, radiators, etc., and is less likely to peel off its fins.

In this specification, aluminum includes not only pure aluminum but also aluminum alloys.

Conventional technology In the past, when manufacturing aluminum heat exchangers, after combining aluminum tubes and fins, a bonding slurry containing zinc chloride and a solvent as the main components was applied to the areas where they came into contact. , by heating,
It is already known to join a tube and a fin through a layer of brazing material containing zinc as a main component.

Problems to be Solved by the Invention However, in the aluminum heat exchanger manufactured by the above-mentioned conventional method, since the structure of the joint part is not dense, for example, in a corrosion resistance test, the boundary part of the joint part between the fin and the brazing metal layer is particularly The problem is that the fins are eroded, cracks occur from the boundary portions, and the fins are relatively easy to peel off, resulting in a decrease in heat exchange performance and poor durability.

An object of the present invention is to solve the problems of the prior art described above, and to provide a heat exchanger in which tubes and fins are brazed by the method described above, the brazing is of good quality and the structure of the joint part is a dense dendrite structure. Therefore, it is an object of the present invention to provide an aluminum heat exchanger which has very little peeling of fins, can maintain excellent heat exchange performance for a long period of time, and has excellent durability.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a method in which a tube and a fin are coated with a bonding slurry mainly composed of zinc chloride, a copper compound, and a solvent, and then heated. The gist of this paper is an aluminum heat exchanger with less fin peeling, which is characterized by being bonded via a brazing material layer mainly composed of zinc and copper.

In the above, ordinary pure aluminum and aluminum alloy are used as the aluminum material constituting the fins and tubes.

The bonding slurry is mainly composed of zinc chloride, a copper compound, and a solvent.

Examples of the copper compound include copper chloride (CuC12) and fluorinated steel (Cub, .2H20).

Further, as the above-mentioned solvent, ketones such as acetone, alcohols, aldehydes, water, nitriles, esters, lactones, ethers, etc. are used alone or in combination.

In the above, the amounts of zinc chloride and solvent used in the bonding slurry composition containing zinc chloride and a solvent as main components are preferably \'1.1.

Further, the amount of the copper compound added is 0.5 to 5% by weight, preferably 1 to 3% by weight based on the total amount of the bonding slurry.

The above bonding slurry may contain ammonium decaide such as ammonium chloride, sodium fluoride, sodium iodide, sodium bromide, acidic sodium fluoride, acidic potassium fluoride, potassium fluoride, lithium fluoride, etc. as a flux. may be added.

When manufacturing an aluminum heat exchanger, according to the present invention, the bonding slurry mainly contains zinc chloride, a copper compound such as copper chloride or fluorinated steel, and a solvent, and the bonding slurry is made of aluminum material. with the fins and tubes of
If the fins and tubes are joined through a brazing material layer mainly composed of zinc and copper, which is created by applying and heating this joining slurry, the brazing properties will be extremely good and the structure of the joint will be dense. It becomes a dendrite structure.

Therefore, cracks do not occur at the bonding boundary between the fins and the brazing material layer, and the fins are less likely to peel off.

Note that if water adheres to the surface of the heat exchanger and a local battery is formed, the brazing metal layer side will gradually corrode because the potential of the brazing metal layer is less noble with respect to the fins and tubes. ,
Since this corrosion is surface corrosion, cracks do not occur at the joint boundary between the two, and the fins are less likely to peel off.

In this case, it is preferable to enlarge the fillets of the brazing material layer protruding from both sides of the joint between the fins and the tubes, as this will slow down the wear of the brazing material layer due to surface corrosion and increase the durability of the heat exchanger. .

As mentioned above, the amount of copper compounds such as copper chloride (CuCI2) and fluorinated steel (CuF2 211□0) added is 0.5 to 5% by weight, preferably 1% by weight, based on the bonding slurry. If the amount of copper compounds added is less than 0.5% by weight relative to the bonding slurry, the amount of copper compounds added is too small and the brazing However, the structure of the joint portion does not form a dense tentorite structure, and the above-mentioned effects cannot be expected. Further, if the amount of these copper compounds added exceeds 5% by weight, this is not preferable since it may cause a problem of poor bonding.

Embodiments Next, embodiments of the present invention will be described together with comparative examples with reference to the drawings.

Example] First, pure aluminum (AIloo) was used as the aluminum material constituting the meandering flat tubes (2) of the heat exchanger (1) shown in Fig. 1, and the corrugated fins (3) were constituted. Aluminum material (thickness 0.1
6 mm), pure aluminum (AIloo) was used.

Next, after combining these tubes (2), corrugated fins (3), and aluminum joint members (4) as shown in Figure 1, this combination was treated with 50% by weight of zinc chloride and copper chloride ( CuCi2) 2. It was immersed in a bonding slurry consisting of 1% by weight of a solvent and 47.9% by weight of acetone. Then, after taking these out from the slurry, they were heated to 420° C. with a gas burner, and after the heating was finished, they were washed with water to remove the remaining slurry, thereby producing a heat exchanger.

Example 2 The same aluminum materials as in the first example were used for the tube (2) and fins (3), but
As a bonding slurry, 50% by weight of zinc chloride, copper fluoride (
A heat exchanger (1) was produced in the same manner as in Example 1 above using a solvent consisting of 48.4 wt.

Comparative Example For comparison, the same aluminum material as in the first embodiment was used for the tubes and fins of the heat exchanger, but 50% zinc chloride was used as the bonding slurry.
A conventional heat exchanger was manufactured as in Example 1 above using a conventional bonding slurry consisting of 50% by weight and a solvent of 50% by weight and acetone.

In order to evaluate the performance of the heat exchanger (1) of Examples 1 and 2 and the heat exchanger of the comparative example, these heat exchangers were subjected to a corrosion resistance test, that is, a CCT test (combined cycle test) for 100 cycles. As a result of the test, in the heat exchangers (1) of Examples 1 and 2, after 100 cycles of the test, only cracks occurred at the boundary between the fins (3) and the brazing metal layer (5), and the fins (3) There was almost no peeling.

On the other hand, in the heat exchanger of the comparative example, the boundary between the fin and the brazing material layer was clearly eroded, and the CCT
After 80 cycles of testing, cracking occurred at the boundary and the fin was peeled off.

Effects of the Invention As described above, in the heat exchanger according to the present invention, the tubes and fins are coated with a bonding slurry containing zinc chloride, a copper compound, and a solvent as main components, and then heated. Since they are joined via a brazing material layer mainly composed of copper, the brazing properties are good, and the structure of the bonded part is a dense dendrite structure. It is difficult for cracks to occur from the boundary parts of the fins, so there is very little peeling of the fins, and excellent heat exchange performance can be maintained for a long period of time, resulting in excellent durability.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a heat exchanger according to an embodiment of the present invention, and FIG. 2 is a partially enlarged front view showing a joint between a tube and a fin in the heat exchanger. (1)...Heat exchanger, (2)...Tube, (3)
... Fin, (5) ... Brazing metal layer. that's all

Claims (1)

[Claims] The tube (2) and the fin (3) are coated with a brazing filler metal layer (5) mainly composed of zinc and copper, which is formed by applying and heating a bonding slurry mainly composed of zinc chloride, a copper compound, and a solvent. ) is an aluminum heat exchanger with less fin peeling.