WO2005030434A1

WO2005030434A1 - Brazing flux powder of aluminum material and method of applying the flux powder

Info

Publication number: WO2005030434A1
Application number: PCT/JP2004/014178
Authority: WO
Inventors: Kazuyoshi Honda; Satoru Saitoh
Original assignee: Jemco Inc.; Mitsubishi Materials Corporation
Priority date: 2003-09-29
Filing date: 2004-09-28
Publication date: 2005-04-07
Also published as: JP2005125406A; JP4845360B2

Abstract

An improved brazing flux powder of aluminum material comprising KAlF4, K2AlF5, K2AlF5·H2O and K3AlF6 wherein Mg is contained in a proportion of 0.1 to 1.0 wt.%. In the composition of this flux powder, the molar ratio of K/Al is in the range of 1.00 to 1.20 while the molar ratio of F/Al is in the range of 3.80 to 4.10. In the X-ray diffractometry of the powder, the intensity of diffraction peak wherein 2θ ascribed to K2AlF5·H2O lies between 44 deg. and 45 deg. is not greater than 12% of the maximum peak intensity ascribed to KAlF4.

Description

Specification

Flux powder for brazing aluminum-based material and method of applying this flux powder

Technical field

The present invention relates to a flux powder suitable for brazing an aluminum-based material containing magnesium and a coating method using the flux powder.

Background art

[0002] Conventionally, in brazing an aluminum-based material, an aluminum silicon (A1-Si) eutectic alloy having a slightly lower melting point than an aluminum-based material has been used as a brazing material. In order to bond the brazing material and the aluminum-based material satisfactorily, it is necessary to remove the oxide film formed on the surface of the aluminum-based material, and a fluoride flux is used to remove the oxide film. ing. Of these, potassium fluoride (KF) -aluminum fluoride (A1F) -based complex

Three

Non-corrosive flux consisting of potassium fluoroaluminate) can be applied or sprayed directly on the surface of aluminum-based material, can be continuously treated in a nitrogen atmosphere furnace, and the flat thin film after brazing is stable. It is the most widely used because it has various excellent performances such as low cost and high quality without the need to remove the generated flux powder. This KF-A1F flux is used in the molten state of KA1F, the main component.

3 4

It reacts with the oxide film on the surface of the minimum material to bond the active aluminum material to the molten brazing material.

[0003] On the other hand, by reducing the thickness of the aluminum member, the amount of material used is reduced, and the cost is reduced. The aluminum-based material containing magnesium (Mg), which has excellent strength and corrosion resistance, is designed to reduce the weight of the member. Use is being considered.

[0004] The KF-A1F-based flux is used for brazing aluminum-based materials containing Mg.

Three

Has the drawback of not exhibiting sufficient performance. Specifically, when brazing an aluminum-based material containing more than 0.4% by weight of Mg, the flux reacts with Mg during brazing as shown in the following equation (1). KA1F, which is the main component, is consumed and

Four

Point KMgF and A1F are generated and precipitated. This KMgF or A1F determines the melting point of the flux layer. And significantly reduce the fluidity during melting. Therefore, the molten flux does not have sufficient spreadability, and KA1F, the main component of the flux, is consumed by the reaction.

Four

The oxide film on the surface of the aluminum-based material is not sufficiently removed.

3Mg + 3KA1F → 3KMgF (s) 丄 + A1F (s) 丄 + 2AU …… (1)

4 3 3

[0005] Accordingly, in the flux currently used, brazing to an aluminum-containing material containing Mg must be performed by applying about 5 times the amount of application to an aluminum-based material without containing Mg. However, there was a problem that sufficient spreadability was not obtained and the oxide film on the surface of the material was not removed.

[0006] Furuoro containing As a measure to solve this problem, a single I匕合product display aluminum fluoride 6 0 50 weight ^_0/0 At, potassium fluoride 40- 50 weight ^_0/0 aluminum potassium © beam or full O b mixed composition 100 by weight ^_0/0 of potassium aluminate and aluminum fluoride, brazing containing aluminum fluoride ammon 5- 15 weight ^_0/0 for the total amount of (See, for example, Patent Document 1.) o The flux described in Patent Document 1 can braze aluminum-based materials with an Mg content of around 2% by weight. I have.

[0007] Furthermore, in terms of a single compound, aluminum fluoride and cesium fluoride have a composition corresponding to a molar ratio of cesium fluoride of 67Z33-126Z74. A brazing flux having a mixed composition strength has been proposed (for example, refer to Patent Document 2). _{0 In the} flux disclosed in Patent Document 2, an aluminum-based material having an Mg content of 1% by weight or less is used. Can be used for brazing.

Patent Document 1: JP-A-60-184490 (Claims (1), page 3, upper left column, line 15, upper right column, second line)

Patent Document 2: JP-A-61-162295 (Claims)

Disclosure of the invention

Problems to be solved by the invention

[0008] However, in the flux disclosed in Patent Document 1, a large amount of harmful fumes of ammonium fluoride (NHF) is generated during the brazing process, so that corrosion of equipment, safety and health, and public safety are required. The harm's perspective has a big problem.

Further, in the flux disclosed in Patent Document 2, since expensive cesium is used as a raw material, it is not economically practical for brazing, which is generally used, because it is expensive. Further, since the cesium compound contained in the cesium-containing flux has a hygroscopic property, the use of the cesium-containing flux causes a problem of corrosion of brazing equipment.

[0009] An object of the present invention is to provide a brazing method for brazing an aluminum-based material containing Mg, which has good spreadability, is non-corrosive, has excellent safety, and is relatively inexpensive and economically excellent. An object of the present invention is to provide a flux powder for brazing an aluminum-based material that can be used for general purposes and a method for applying the flux powder.

Means for solving the problem

[0010] The first embodiment of the present invention relates to a method in which KA1F, KA1F, KA1F

4 2 5 2 5 2 3 6 This is an improvement in the flux powder used for brazing aluminum-based materials containing 0.1% by weight to 1.0% by weight, each containing Mg. Its characteristic composition is that the composition of the powder is κΖ

The molar ratio of A1 is 1.00-1.20 and the molar ratio of FZA1 is 3.80-4.10. When the powder is analyzed by X-ray diffraction analysis, the 2 A force of 4 ° -45deg due to K A1F · Η Η Maximum times between

2 5 2

The folding peak intensity is less than 12% of the maximum peak intensity by KA1F.

Four

[0011] In the present invention, the K A1F when the powder is subjected to X-ray diffraction analysis within the range of the molar ratio of K / A1 of 1.00-1.20 and the molar ratio of F / A1 of 3.804.10. · 2 Θ force 4deg by Η Ο

2 5 2

Maximum diffraction peak intensity existing during 45deg is 12% of the maximum peak intensity by KA1F

Four

The composition and crystallinity of K A1F · Η 形成 are sufficiently formed and grown as specified below.

2 5 2

Control not to. The flux powder defined as above increases the fluidity and spreadability at the time of melting compared to the conventional flux powder and reduces the oxide film on the material surface when brazing the Mg-containing aluminum-based material. The coating amount can be greatly reduced compared to the case where a conventional flux powder is used for an Mg-containing aluminum-based material, and good brazing can be performed. In addition, it is non-corrosive and excellent in safety, relatively inexpensive and economical, and can be widely used for general purposes.

[0012] The flux powder has a K / A1 molar ratio of 1.05-1.15 and an FZA1 molar ratio of 4.00- 4. It may be in the range of 10.

[0013] The flux powder has a melting peak height of 560 ° C detected in a temperature range of 550 ° C to 560 ° C when the powder is subjected to Differential Thermal Analysis (hereinafter, referred to as DTA analysis). It may be higher than the melting peak height detected in the temperature range above C.

[0014] In this case, when the powder is subjected to DTA analysis, the melting peak height detected in the temperature range of 550 ° C to 560 ° C is higher than the melting peak height detected in the temperature range exceeding 560 ° C. If so, the composition and crystallinity of K A1F · Η 制 should not be sufficiently formed and grown.

2 5 2

It is half IJ controlled.

[0015] The flux powder may have a content of fine powder having a particle size of 10 m or less of 17 to 33% by weight, and the powder may have a 200 mesh sieve transmittance force of 0% or more.

[0016] Further, the flux powder may have a content of fine powder having a particle size of 10 m or less of 19 to 28% by weight and a powder having a 200 mesh sieve transmittance of 50% or more! .

In this case, by adjusting the particle size to the above-mentioned particle size, a powder suitable for use in electrostatic coating can be obtained.

[0018] The flux powder may have a content of fine powder having a particle diameter of 10 µm or less of 25% by weight or more.

In this case, by adjusting the particle size to the above-mentioned particle size, a powder suitable for use in wet coating can be obtained.

Another embodiment of the present invention is a method for applying a flux powder, wherein the flux powder is applied to a brazing position of an aluminum-based material by electrostatic coating.

[0021] According to the present invention, the washing step and the drying step before and after the coating step, which are performed in the conventional wet coating, are not required, so that the brazing step can be simplified.

The invention's effect

The flux powder of the present invention contains KA1F, KA1F, KA1F.HO and KA1F in the powder.

This is an improvement in the flux powder used for brazing aluminum-based materials containing 4 2 5 2 5 2 3 6 and having a Mg content of 0.1% by weight to 1.0% by weight. Its characteristic composition is that the composition of the powder has a molar ratio of KZA1 of 1.00-1.20 and a molar ratio of FZA1 of 3.80-4.10. The maximum force existing between 2 ° and 4 ° —45 ° due to Ο deg

2 5 2

The diffraction peak intensity is less than 12% of the maximum peak intensity by KA1F.

Four

[0023] The flux powder defined in this manner has a sufficient composition and crystallinity of K A1F · Η Ο It is controlled so that it does not grow and grow, so that when brazing aluminum-based materials with a Mg content of 0.1% by weight to 1.0% by weight, the fluidity and spread when melting compared to conventional flux powders The coating performance is improved, and the oxide film on the material surface is also excellently removed.The coating amount is significantly reduced for Mg-containing aluminum-based materials compared to the case where conventional flux powder is used. You can get brazing. Moreover, it is non-corrosive and excellent in safety, and is relatively inexpensive and economically excellent, and can be widely used for general purposes.

Brief Description of Drawings

FIG. 1 is a flow chart showing a method for producing a flux powder according to the present invention.

FIG. 2 is a diagram showing a DTA curve of No. 1 sample.

FIG. 3 is a view showing a DTA curve of No. 2 sample.

FIG. 4 is a diagram showing a DTA curve of No. 19 sample.

[FIG. 5] FIG. 5 is a graph showing the relationship between the molar ratio of KZA1 and the relative strength in Samples No. 1 to No. 23.

[FIG. 6] FIG. 6 is a graph showing the relationship between the molar ratio of KZA1 and the spreading property in Samples No. 1 to No. 23.

[FIG. 7] FIG. 7 is a diagram showing the relationship between relative intensity and spreadability in Samples No. 1 to No. 23.

FIG. 8 is a graph showing the relationship between the content of fine powder having a particle size of 10 m or less and the transmittance of a 200 mesh sieve in a No. 24-No. 42 flux powder sample.

[FIG. 9] FIG. 9 is a diagram showing the particle size distribution of the No. 24, No. 29, No. 30, and No. 40 flux powder samples.

FIG. 10 is a graph showing the relationship between the particle size distribution of a No. 24-No. 42 flux powder sample and the amount of flux applied to an aluminum plate.

FIG. 11 is a graph showing the relationship between the particle size distribution of No. 24-No. 42 flux powder samples and the amount of flux applied per lm ² .

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] In addition to KA1F in the KF-A1F flux powder, if K A1F or A1F is present,

3 4 2 5 3 6

For Mg-containing aluminum-based materials, the reactions shown in the following equations (2) and (3) occur 3Mg 2KA1F K A1F-3KMgF (s) i KA1F 2AU (2)

4 2 5 3

3Mg 2KA1F K A1F-3KMgF (s) i K A1F-2AU (3)

3 6 2 5

[0026] By such a reaction, consumption of KA1F is suppressed, and precipitation of high melting point A1F is also prevented.

4 3

be able to. Production of conventionally used KF-A1F flux powder

Three

Is produced by a wet reaction represented by (a)-(c) in FIG. 1 and the following equation (4) and equation (6).

Al (OH) + 4HF → HA1F + 3H 0 …… (4)

3 4 2

HA1F + KOH → KA1F \ …… (5)

4 4

HA1F + HF + 2KOH → K A1F · Η 0 丄 + Η 0 …… (6)

4 2 5 2 2

[0027] The obtained reaction product is subjected to a filtration and washing step, a step of drying the flux powder, and a particle size distribution and particle shape of the powder, as shown in (d) to (f) in Fig. 1, respectively. It is commercialized through the process of controlling

On the other hand, the obtained flux powder is subjected to K A1F · Η by a wet reaction represented by the formula (6).

2 5 2

Crystal grains of the form Ο will be present. K A1F containing this water of crystallization

2 5 2

In addition, water vapor is generated in the brazing process to increase the oxidation film on the surface of the aluminum-based material. Therefore, the fluidity of the flux is reduced.

[0029] The present inventors have found that in brazing an Mg-containing aluminum-based material, it is possible to improve the fluidity of the flux during melting and suppress the reaction between Mg and the flux on the surface of the Mg-containing aluminum-based material. We proceeded with the development of a flux that can be used to braze the contained aluminum-based material. The composition of the reaction product obtained by the production method shown in (a)-(c) in Fig. 1 is calculated as K / A1 mono kttl. 1.20, F / A1 mono ktt3. The composition and crystal of K A1F · Η となっ which are factors that reduce the fluidity of flux by specifying within the range of 80 to 4.10

2 5 2

The crystallinity is controlled so as not to form and grow sufficiently, and K A1F

2 5 2

It has been found that by using particles having crystal defects, a flux powder having excellent spreadability at the time of melting at a low melting temperature can be obtained. The flux powder having such a composition has an increased fluidity and spreadability upon melting, and is not only excellent in removing an oxidized film on the surface of the material, but also has an excellent effect on the exchange of Mg and flux on the surface of the aluminum-based material. Good brazing while suppressing the reaction It has been found that dispersibility can be obtained.

[0030] The flux powder of the present invention contains KA1F, KA1F, KA1F.HO and KA1F in the powder.

2 5 2

The diffraction peak intensity is less than 12% of the maximum peak intensity by KA1F. Powder

Four

Composition power of powder ZA1 molar ratio 1.00-1.20, FZA1 molar ratio 3.80-4.10. Within the range of K A1F · Η 分析 when powder is analyzed by X-ray diffraction 44 ° 45deg Exists between

2 5 2

The maximum diffraction peak intensity to 12% or less of the maximum peak intensity by KA1F.

Four

Control so that the composition and crystallinity of K A1F · Η しない do not form and grow sufficiently

2 5 2

I do. The flux powder specified in this manner increases the fluidity and spreadability during melting when brazing an Mg-containing aluminum-based material compared to conventional flux powder, and removes the oxide film on the material surface. The coating amount can be greatly reduced compared to the case where the conventional flux powder is used for the Mg-containing aluminum-based material, and good brazing can be obtained. In addition, it is non-corrosive and excellent in safety, relatively inexpensive and economical, and can be widely used for general purposes. The flux powder of the present invention is a flux powder used for brazing an aluminum-based material having a Mg content of 0.1% by weight to 1.0% by weight, and particularly an aluminum powder having a Mg content exceeding 0.5% by weight. It is suitable for use as a system material. The composition of the powder is in the range of KZA1 molar ratio 1.00-1.20, FZA1 molar ratio 3.80-4.10, preferably KZA1 molar ratio 1.05-1.15, FZA1 molar ratio 4.00. —4. In the range of 10. X-ray diffraction analysis of K A1F · Η 2 at 2 4 force 4deg—

2 5 2

The maximum diffraction peak intensity existing during 45 deg is the maximum peak intensity of KA1F.

Four

% Or less.

[0031] The flux powder of the present invention has a melting peak height detected in a temperature range of 550 ° C to 560 ° C when the powder is subjected to DTA analysis, and a melting peak height detected in a temperature range exceeding 560 ° C. It is defined to be higher than the peak height. 550 ° C — Melting peak height at 560 ° C If the melting peak height is higher than the temperature range above 560 ° C, the composition of K A1F

2 5 2 It can be seen that the crystallinity is controlled so as not to form and grow sufficiently.

When the flux powder of the present invention is used in an electrostatic coating method, the content of the fine powder having a particle size of 10 m or less is 17 to 33% by weight, and the powder has a 200 mesh sieve transmittance force of 0% or more. It is preferable that By adjusting the flux powder within the above range, high paintability can be obtained without the flux powder adhering to the pipes or nozzles of the electrostatic coating device or causing blockage. This is because the properties of the flux powder of the present invention are different from those of the conventional flux fine powder containing a large amount of columnar particles, so that even if the content of the fine powder having a particle size of 10 m or less is increased, the sieve transmittance and the like are increased. This is because the powder fluidity does not decrease. If the content of the fine powder having a particle size of 10 m or less is less than the lower limit, if the amount applied to the Mg-containing aluminum material exceeds the upper limit that is not practically sufficient, it will adhere to the piping and nozzles of the electrostatic coating equipment. Or may cause blockage. Among them, it is particularly preferable to carry out electrostatic coating using a flux powder having a content of fine powder having a particle size of 10 m or less of 19 to 28% by weight and a transmittance of a 200 mesh sieve of 50% or more. . When the flat powder of the present invention is used in a wet coating method, the content of the fine powder having a particle size of 10 m or less is preferably 25% by weight or more.

[0033] The flux powder of the present invention makes it difficult to braze in the past and barely carried out by applying a large amount of flux to achieve an aluminum content of 0.1 wt%-1.0 wt%. Brazing Strength of Pummeled Material It is possible to reduce the amount to be applied to an aluminum-based material to almost the same amount without containing Mg, and to achieve good brazing property.

Next, a method for applying a flux powder of the present invention will be described.

In the coating method using the flux powder of the present invention, the flux powder of the present invention, preferably a fine powder having a particle size of 10 μm or less and having a content of 20% by weight or more, is dispersed and dispersed in a solvent. Good coating can be performed by adjusting the liquid and applying the dispersion to the brazing position of the Mg-containing aluminum-based material by wet coating. Flux powder with a content of fine powder with a particle size of 10 m or less with a content of 20% by weight or more has low sedimentation in a solvent and is suitable for application with a slurry in which such flux powder is dispersed. Excellent adhesion to brazing surface.

[0035] On the other hand, in the conventional method of applying a flux powder, the flux powder is dispersed in water. It is common to apply about 5 to 10 g / m ^{2 to the} material to be coated by spraying or dipping using a slurry. In this wet coating, the material is coated before coating. A solvent washing process for the material, a drying process after coating, and a drying facility are required. In this wet coating, the performance of brazing Mg-containing aluminum-based materials cannot be demonstrated, as the amount of moisture brought into the furnace for brazing may increase.

[0036] Therefore, in the method for applying a flux powder of the present invention, the flux powder of the present invention is used, and dry flux powder is applied by an electrostatic coating method to perform dry coating. In this dry coating, the content of fine powder having a particle size of 10 / zm or less is 17 to 33% by weight, preferably 20 to 25% by weight, and the powder has a 200 mesh sieve permeability of 0% or more. The obtained flux powder is suitable. Flux powder with a content of fine powder with a particle size of 10 / zm or less of 17-33% by weight and a powder power of 200 mesh sieve permeability of 0% or more is required for dispersibility required for powder dispersion. And has fluidity. Therefore, the washing step and the drying step before and after the coating step performed in the conventional wet coating are not required, so that the brazing step can be simplified. Therefore, it is advantageous in terms of cost, and a greater economic effect can be produced by combining the flux powder of the present invention with the coating method using the flux powder of the present invention.

[0037] When the content of the fine powder having a particle size of 10 m or less is 25% by weight or more in the flux powder of the present invention, satisfactory coating can be performed even by a wet coating method.

Example

Next, examples of the present invention will be described in detail together with comparative examples.

First, flux powder samples having the composition ratios shown in the following Table 1 were manufactured up to No. 1 to No. 5. The manufactured No. 1-No. 5 samples had a KZA1 molar ratio within the range of 1.05-1.17 and an FZA1 molar ratio within the range of 3.84-4.08. The relative strength at 2 deg. 4.5deg by A1F · Η Η was 5-10%. No.

2 5 2

Fig. 2 shows a DTA curve obtained by DTA analysis of one sample, and Fig. 3 shows a DTA curve obtained by DTA analysis of No. 2 sample.

[0039] As is clear from Figs. 2 and 3, each of the No. 1 and No. 2 sampnoles 550 ^o C-560 Melting peak height force detected in the temperature range of ° C The melting peak height is higher than the melting peak height detected in the temperature range exceeding 560 ° C, and the composition and crystallinity of K A1F

2 5 2

It grows and grows.

Next, an aluminum-based material A having a Mg content of 0.8% by weight was prepared. Next, 2 mg of the sample was applied to the surface of the material A, placed in an atmosphere furnace maintained at 600 ° C, and held for about 6 minutes. After heating, the material was taken out of the atmosphere furnace, and the spreadability of the sample melted on the material surface was measured. Table 1 shows the spreadability test results for aluminum material A. Fig. 5 shows the relationship between the KZA1 molar ratio and the relative strength, Fig. 6 shows the relationship between the KZA1 molar ratio and the broadening property, and Fig. 6 shows the relationship between the relative strength and the spreading property. Figure 7 shows each of them.

The spreadability was measured in the same manner as in Example 1 except that flux powder samples No. 6 to No. 23 having the composition ratios shown in Table 1 below were used. The samples No. 6, No. 7, No. 9, No. 11, No. 14, No. 16—No. 20, No. 22 and No. 23 used were KZA1 mole ratio, FZA1 mole. The ratio and relative strength are out of the range of the present invention, respectively, and the samples of No. 8, No. 10 and No. 12 have the KZAl molar ratio and the relative strength out of the range of the present invention, and No. 13 and No. In each of the 15 samples, the KZAl molar ratio and the FZA1 molar ratio were out of the range of the present invention, and in the No. 21 sample, the FZA1 molar ratio was out of the range of the present invention. FIG. 4 shows a DTA curve diagram obtained by subjecting the No. 19 sample to DTA analysis.

[0042] As is clear from Fig. 4, the No. 19 sample has a melting peak height detected in a temperature range of 550 ° C to 560 ° C, and a melting peak height detected in a temperature range exceeding 560 ° C. And the composition and crystallinity of K A1F · Η Ο are sufficiently formed and grown.

2 5 2

I understand.

[Table 1]

As is clear from Fig. 5, the flux powders of No. 6—No. 20, No. 22 and No. 23, whose K / A1 molar ratio indicated by diamonds in the figure exceeds 1.20, Medium, square It can be seen that the relative strength tends to be higher than the flux powder within the indicated KZAl molar ratio of 1.00-1.20. Also, as is evident from FIG. 6, flux powder having a KZA1 molar ratio exceeding 1.20 tends to have a lower spreadability than flux powder having a KZA1 molar ratio in the range of 1.00-1.20. There is not enough wide strength S required for Mg-containing aluminum material. Further, as is clear from FIG. 7, the fluxes of No. 6—No. 12, No. 14, No. 16—No. 20, No. 22, and No. It can be seen that the spreadability tends to be lower than that of a flux powder with a strength of 12% or less.

Among the flux powder samples manufactured in Example 1, the flux powder samples shown in Table 2 below were manufactured up to No. 24 to No. 42. The content of these flux powder samples following fine powder particle size 10 m is 11. 6 33.8 weight ^_0/0, 200 mesh sieve permeability of powder 0% 84. - which were prepared in 37% It is. The following electrostatic coating test was performed using the manufactured No. 24-No. 42 flux powder sample.

[0046] In the electrostatic coating test, first, the Mg content of 40mm X 50mm, thickness 1.0mm was 0.4-0.

A 5% by weight aluminum plate, a dried 250 ml polystyrene wide-mouth container, and 10.0 g of the above flux powder sample were prepared. Next, the entire surface of the aluminum lithographic plate was washed with acetone, and the washed aluminum plate was dried at 100 ° C. for 30 minutes, and the weight was measured. Next, 10.0 g of the flux powder sample was placed in the dried polystyrene wide-mouthed container, and the wide-mouthed container was sealed with a polypropylene lid, and the sealed wide-mouthed container was stirred for 2 minutes with a shaker to obtain the wide-mouthed container. The flux powder sample inside was charged. Next, place the aluminum plate that was previously washed with acetone into a polystyrene wide-mouth container, close the lid again, shake the sealed wide-mouth container six times, and remove the charged flux powder sample in the wide-mouth container from aluminum. It was attached to the front and back surfaces of a flat plate. Further, with the force of the shaken wide-mouthed container, the aluminum plate on which the flux powder sample was adhered was taken out with tweezers and its weight was measured. The weight difference between the aluminum plate to which the flux powder sample was attached and the weight difference between the aluminum plate before the acetone-washed flux powder sample and the flux powder sample adhered to the aluminum plate were also determined. The pull weight was calculated. Table 2 below shows the particle size distribution, the cumulative weight at the particle size, and the results of the electrostatic coating test of the No. 24 to No. 42 flux powder samples. Fig. 8 shows the relationship between the content of fine powder having a particle size of 10 μm or less and the transmittance of a 200 mesh sieve in each flux powder sample, and Fig. 9 shows No. 24, No. 29, No. 30, and No. 40 the particle size distribution of the flux powder samples, each flux powder sample in Figure 10 the flux powder sample application amount of relationship to particle size distribution and aluminum plates of each flux powder sample in Figure 11 particle size distributions and lm ² per The relationship between the applied amounts of the flux powder sample is shown.

[Table 2]

As is evident from FIG. 8, the content of fine powder having a particle size of 10 μm or less and the 200-mesh sieve permeability have a correlation, and the smaller the fine powder content, the higher the sieve permeability and the finer the sieve permeability. It can be seen that the sieve transmittance decreases as the fine powder content increases. From this relationship, it can be seen that the higher the proportion of the fine powder, the easier the clogging becomes.

[0049] Generally brazing to the aluminum material, the flux coating amount has been performed in 4 one 10 g / m ² of within range, low to remove the oxide formed on the aluminum material surface layer Kutomo It is considered that a flux of 4 gZm ² or more needs to be applied. Therefore, 0.5 4-0. 5 wt ^_0/0 Mg-containing fluxes powder sample application amount of aluminum flat sided 20cm ² (40mm X 50mm) is 4g / m ² or more, the amount of deposition of an aluminum flat sided Those of 17 mg or more were regarded as acceptance criteria in the electrostatic coating test.

[0050] As is clear from Table 2, the results of No. 29- No. 42 flux powder samples fluxing amount 17mg or more to aluminum flat plate, and excellent coating weight 4. 3 g / m ² per lm ² Obtained. In the case of the No. 24 flux powder sample, which has a low content of fine powder, for example, as shown in Fig. 9, the proportion of large particles exceeding 10 m is high.This large particle has a large aluminum surface force. It is considered that the rate of adhesion to the flat plate decreased. From the results of FIGS. 10 and 11, it can be seen that the coating amount increases as the content of the fine powder having a particle size of 10 m or less increases, and the coating amount decreases as the content decreases. The reason is considered to be that if there are many large particles exceeding 10 μm in diameter, the aluminum surface force tends to fall off, and the rate of adhesion to the aluminum flat plate decreases, so that a sufficient coating amount cannot be secured. The conventional flux powder had a disadvantage that the sieve transmittance and the powder fluidity were reduced when the content of particles having a small particle size was increased. Since the particle shape is different from that of the fine powder containing a large amount of fine powder, even if the content of the fine powder having a particle size of 10 μm or less increases, the sieve transmittance and the powder fluidity do not decrease. In addition, when No. 24—No. 42 flux powder samples were applied to aluminum using an electrostatic coating device, pipes and pipes were used for No. 40 and No. 41 flux powder samples with a 200 mesh sieve transmittance of 50% or less. Some nozzle clogging began to occur, and pipes and nozzles were clogged with a No. 42 flux powder sample with a 200 mesh sieve permeability of 0% or less. Therefore, particle size 10 mu m or less fine fine powder content of 17 33 wt ^_0/0, 200 mesh sieve transmittance force of 0% or more of powder No. 29- No. 41 flux powder samples electrostatic Especially suitable for use in electropainting I understood.

[0051] Note that also aluminum flat plate and 0.05 wt ^_0/0 Mg-containing aluminum flat plate containing no Mg, but the electrostatic coating test using a flux powder samples No. 24- No. 42 having conducted, the Test results almost similar to those shown in Table 2 were obtained.

Industrial applicability

[0052] The flux powder of the present invention can be applied not only to brazing of an Mg-containing aluminum material, but also to brazing of an aluminum material containing no Mg.

Claims

The scope of the claims

[1] The powder contains KAIF, KAIF, KAIF

4 2 5 2 5 2 3 6

In a flux powder used for brazing aluminum-based materials with a 0.1% by weight—1.0% by weight

The composition power of the powder has a range of ZA1 molar ratio of 1.00-1.20 and FZA1 molar ratio of 3.80-4.10.

When the powder was analyzed by X-ray diffraction, K A1F · Η 2

2 5 2

The maximum diffraction peak intensity existing between them is 12% or less of the maximum peak intensity by KA1F.

Four

A flux powder for brazing aluminum-based materials, characterized in that:

[2] The flux powder had a K / A1 molar ratio of 1.05-1.15 and an FZA1 molar ratio of 4.00-4.

The flux powder for brazing an aluminum-based material according to claim 1, having a range of 10.

[3] The height of the melting peak detected in the temperature range of 550 ° C-560 ° C when the powder is subjected to differential thermal analysis is higher than the height of the melting peak detected in the temperature range exceeding 560 ° C. Flux powder for brazing aluminum-based materials described in 1.

[4] The brazing of the aluminum-based material according to claim 1, wherein the content of the fine powder having a particle size of 10 m or less is 17 to 33% by weight, and the powder has a 200 mesh sieve permeability of 0% or more. For flux powder.

[5] The brazing of the aluminum-based material according to claim 1, wherein the content of the fine powder having a particle size of 10 µm or less is 19 to 28% by weight, and the powder has a 200 mesh sieve transmittance of 50% or more. Flux powder.

6. The flux powder for brazing aluminum-based material according to claim 1, wherein the content of the fine powder having a particle size of 10 μm or less is 25% by weight or more.

[7] A method for applying a flux powder according to claim 4, wherein the flux powder is applied to a brazing position of an aluminum-based material by electrostatic coating.

[8] A method for applying a flux powder according to claim 6, wherein the flux powder is applied to a brazing position of an aluminum-based material by wet coating.