JPH01249294A - Precoated brazing filler metal-coated metal sheet, production thereof and using method therefor - Google Patents

Abstract

PURPOSE:To uniformly and simply braze wide joining area of metal sheet at a stroke by coating brazing filler metal suspending in solvent together with organic binder on the surface of the metal plate and removing the solvent by preheating. CONSTITUTION:Coiled stainless steel sheet 1 is rewound and inserted into coating unit 2 and the powdery brazing filler metal (Ni-Cr-P series brazing filler metal, etc.) in a vessel 4, the organic binder (polyvinyl alcohol series, etc.) in a vessel 6 and the solvent are mixed, suspended and coated on the steel plate 1 with spray guns 8. Successively, the continuously running steel sheet 1 is sent into drying unit 10 providing double structure 9 and dried under insert gas atmosphere of Ar, etc., to vaporize the solvent and wound to the coil. By this method, the brazing can be simply executed to the wide joining area of the stainless steel plate 1 under good condition and a heat exchanger is easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to a brazing material such as N1-Cr-P or Ni-
A metal plate material provided with a coating layer made of Cr-3i brazing material,
For example, it relates to stainless steel plate materials, methods of manufacturing the same, and methods of using the same.

(Conventional technology) Conventional general brazing methods include attaching powdered brazing filler metal to the interface between bonding materials and heating it, or solidifying powdered brazing filler metal with a binder into a plate shape. There are methods such as placing a thin plate brazing filler metal or a ribbon-shaped brazing filler metal made by a rapid solidification method at the bonding interface, and these methods are sufficient when the bonding area is small.

By the way, in recent years, large heat exchangers have been used mainly from the viewpoint of energy conservation, such as for the cold energy use of LNG and the recovery of waste heat from factory wastewater, and the surface area of the heat exchanger plate has increased to 4-3.
For example, heat exchangers made of AQ or AQ alloy have been put into practical use. The heat exchanger plate of this large-sized heat exchanger, as shown in FIG.
It is assembled by brazing. This brazing is performed by a furnace brazing method under vacuum conditions using a material clad as a low melting point AQ gold alloy brazing material.

(Problems to be Solved by the Invention) However, in recent years, the heat exchange temperature has become higher and the apparatus itself has become larger. Moreover, heat exchange conditions have become more stringent and they have come to be used in more corrosive environments. Therefore, compared to the above-mentioned M alloy heat exchanger, a heat exchanger that is superior in corrosion resistance, has high high temperature strength, can be used at higher temperatures, and has an excellent heat exchange rate is beginning to be required.

In order to realize such a heat exchanger, it is preferable to use stainless steel W4, which has excellent high temperature resistance and corrosion resistance, as the material.In this case, the brazing material to be used for joining the heat exchanger plates is requires a high melting point type brazing filler metal such as N1-Cr-P type or Ni-Cr-5i type. This high melting point type brazing material has conventionally been used in the form of a powder, a rapidly solidified ribbon, a slab or a plate, and is inserted or applied to the joint interface before brazing.

However, in the method of corrugating steel plates for heat exchanger plates and then brazing them, it is difficult to fix the brazing filler metal at the joining interface when it is in powder form, and it is difficult to fix the brazing filler metal at the joining interface when it is in ribbon form. , the width of the ribbon is generally 100
as, it is difficult to cover a wide area.Furthermore, the method of applying a powder brazing suspension solution before brazing not only requires a lot of time for drying and handling, but also makes it difficult to uniformly coat the brazing material. Because it is difficult to apply, it is difficult to braze with uniform strength.

As mentioned above, N1-Cr-P system or Ni-Cr
It has been practically difficult to braze stainless steel plates over a wide joint area at once using existing high-melting-point brazing materials such as -5i type brazing materials.

By the way, as mentioned above, as a technique for brazing a large joint area at once, in addition to brazing using the Af2/AQ alloy craft material mentioned above, there is also an automotive brazing technique in which press-formed stainless steel sheets and Cuf5 are alternately stacked and brazed. There are methods for manufacturing radiators, etc. However, these examples are possible if the material has a brazing material such as a solder material or Cu foil; When joining with filler metal, add a few percent to lower the melting point of the filler metal.
Due to the influence of P, Si and B, which are added in an amount of about 10%, the processability of the brazing filler metal is extremely poor and it is impossible to obtain shapes such as plates and foils. Furthermore, as in the case of Q alloy, N1-Cr-P or Ni is added to the stainless steel plate.
It is extremely difficult to craft a high melting point type brazing filler metal such as -Cr-5i type.

One object of the present invention is to braze temporary stainless steel W4 over a wide joint area at once using a high melting point brazing filler metal such as N1-Cr-P or Ni-Cr-Si brazing filler metal. The purpose is to provide materials and methods of manufacturing them.

Another object of the present invention is to provide a method for manufacturing a heat exchanger plate for a stainless steel heat exchanger and a stainless steel craft steel plate having extremely excellent corrosion resistance using the above-mentioned brazing method.

Furthermore, another object of the present invention is to provide a method for manufacturing a metal material with a corrosion-resistant, heat-resistant and scale-resistant coating layer using the above-mentioned brazing method.

(Means for Solving the Problems) As a result of studying various brazing methods with the intention of improving the above-mentioned drawbacks, the present inventors found that stainless steel plates, etc. The present invention was completed based on the knowledge that by using a so-called pre-coated plate of brazing material, in which a brazing material layer is previously provided on the surface of the metal material, it is possible to braze a large area all at once.

The gist of the present invention is a pre-coated brazing material coated metal sheet material, which is characterized by having a brazing material coating layer made of an organic binder and a brazing material on the surface of the metal sheet material.

Another aspect of the present invention is to apply a brazing filler metal in which a solvent is suspended together with an organic binder to the surface of a metal plate, and then remove the solvent by preheating to form a coating layer of the brazing filler metal. This is a manufacturing method for pre-coated brazing metal coated metal sheets.

Here, the metal plate material mentioned above is a thin plate of stainless steel,
It includes not only foil plates, but also thin plates of Fθ-NI electronic materials, foil plates, thin plates of high alloys such as Incoloy and Inconel, and fi temporary. Due to the nature of the present invention, the metal material can be applied to general metals without any limitations, but the brazing filler metal may be N1-Cr-P or Nj-Cr-3.
This is because when considering the combination with the i-based brazing filler metal, the effects of the present invention are particularly noticeable in the case of the above-mentioned high-grade corrosion-resistant alloy.

Examples of brazing materials other than those mentioned above include Cu-based brazing material, Ag-based brazing material, N1-based brazing material, and the like. All of these are powders and are suspended in a solvent together with an organic binder such as polyvinyl alcohol or methacrylate alcohol, and preferably have an average particle size of 50 μm or less.

In addition, in the case of using a strip coil as the plate material to be treated in the present invention, it becomes possible to perform continuous treatment by applying the brazing material-containing suspension, drying, and heating in a continuous line.

Next, in the brazing method according to the present invention, first, the surface of the pre-coated brazing material-coated metal plate produced as described above is bonded to a mating material (this may be the same pre-coated brazing material-coated metal plate as the case may be). The organic binder is removed by heating the brazing material to a temperature of 300° C. or higher and lower than the melting point of the brazing material under vacuum or an inert gas atmosphere, and then heating to the brazing temperature.

By heating to the brazing temperature, the brazing material provided on the entire surface melts and forms a uniform coating layer on the entire surface. Since a material which itself exhibits excellent corrosion resistance is used as the brazing material, a corrosion-resistant coating layer is thus provided over the whole, and the corrosion resistance of the soldered article is further improved.

, the above vacuum conditions are 10-'' to 10-'a+m1
A vacuum of 1 g or more is preferred. Furthermore, an example of the inert gas is an inert gas such as argon gas. In the case of nitrogen gas, it may be undesirable in some cases because it may dissolve in the molten brazing material.

When manufacturing a heat exchanger plate using the pre-coated brazing metal coated metal plate according to the present invention, a flat plate material that is the pre-coated brazing metal coated metal plate and a different type or the same type of metal formed into a corrugated, corrugated or veined shape are used. At least one set of plate materials is stacked and fixed alternately, and then the organic binder is removed by heating to a temperature of 300°C or higher and lower than the melting point of the brazing material under vacuum or an inert gas atmosphere, and then the brazing temperature is Just heat it to .

According to such a method, the assembly of the heat exchanger plate becomes extremely easy, and operations such as installing, coating, and inserting the brazing material can be omitted, and the effect of cost reduction is particularly remarkable.

Furthermore, as an application example of the present invention, the above-mentioned pre-coated brazing material coated metal material and other metal plate materials are laminated and then heated to a temperature of 300°C or more and below the melting point of the brazing material in a vacuum or an inert gas atmosphere. By removing the organic binder and then heating to brazing temperature, it becomes possible to manufacture a wide range of metal clad materials.

When laminating the metal plates mentioned above, the sheets are initially laminated somewhat loosely to facilitate the escape of gas components when removing the binder, and then heated to the brazing temperature after the gas components from the binder have been sufficiently removed. It is best to fix both plates together.

In yet another application example of the present invention, the metal material provided with the pre-coated brazing filler metal coating layer described above is heated as it is under vacuum or in an inert gas atmosphere to a temperature of 300°C or higher and below the melting point of the brazing filler metal. There is a method of producing a corrosion-resistant surface-coated metal material by removing the mechanical binder and then heating it to a brazing temperature to form a corrosion-resistant coating layer of brazing material.

In this case, since a corrosion-resistant coating is provided on the upper layer of the metal material to be treated, it may be a material that itself does not have much corrosion resistance, such as carbon steel, and its form may also be plate-like. However, it may take any form. Therefore, this method is an extremely simple metal coating method, and the coating thickness can be adjusted simply by adjusting the amount of coating, which has great practical benefits.

(Function) Next, the present invention will be described in detail with reference to the accompanying drawings. Taking a stainless steel plate as a specific example, the present invention will be described in detail. The adhesion properties, a method for manufacturing a heat exchanger plate for a stainless steel heat exchanger, and a method for manufacturing a surface-treated steel sheet obtained using the brazing method of the present invention will be described.

Pre-coated brazing metal and its method; Figure 1 is a schematic explanatory diagram of a continuous manufacturing apparatus for pre-coated brazing metal coated metal sheets. In the figure, a coiled stainless steel sheet 1 is unwound and first inserted into a coating unit 2. be done. The coating unit 2 is composed of a powder brazing material container 4, an organic binder and solvent container 6, and a spray gun 8. The brazing material, organic binder, and solvent are supplied from these containers and mixed and mixed in the spray gun 8. It is suspended and applied to the surface of the steel plate. The continuously running steel strip is then sent to a drying unit 10 equipped with a double seal structure 9,
It is dried under an inert gas atmosphere to evaporate the solvent. As a result, the brazing filler metal powder bound by the binder forms a film on the stainless steel surface, and is firmly fixed to the extent that it will not peel off even if it is subsequently wound into a coil.

Therefore, the brazing material coating layer will not peel off even if it is pre-processed or assembled during brazing.Heating in the drying unit 10 is performed by the induction heater 12.

FIG. 2 is an enlarged schematic diagram of the brazing material coating layer obtained in this manner, in which the shape of each particle 22 of the brazing material powder applied to the metal surface 20 is maintained as it is. The layer thickness of the organic binder 24 is preferably limited to 10 μm or less. The amount of brazing material is not particularly limited, but is generally about 200 to 500 g/m'.

For example, 300% organic binder is applied prior to brazing.
It is decomposed and removed by heating at ~500°C.

Heating should be done with care so that organic matter does not remain as heating residue.

The organic binder used in the present invention is preferably one that can be decomposed and removed by heating as described above, but other desired properties include: (1) ease of application and drying; (2) strong adhesion and flexibility at room temperature. Examples include the fact that it has good properties and does not peel off during coil winding, shear cutting, etc.

In addition, it is preferable to use as little binder as possible within the range that achieves the performance described in (1) above. If it is used in excess, the amount of gas decomposed and generated during heating during brazing will increase, so it is difficult to use in a vacuum atmosphere. , it is difficult to maintain the vacuum atmosphere, and there is an increased tendency for air bubbles to form in the brazed parts.
Causes problems.

Stainless steel brazing method: Apply Ni-Cr-P or Ni-Cr-5t brazing powder to a solvent containing an organic binder on both sides or one side of a cut stainless steel plate or coiled steel plate with a thickness of 1m+w or less. Mixed brazing filler metal? A'! Apply solution A by spraying. After the suspension is applied, the solvent is dried and removed by preheating, leaving a coating layer consisting of the brazing material and organic binder. The brazed test fabric surface of this stainless steel plate was laminated alternately with the stainless thin steel plate to be joined, and
The binder mixed in the solution is decomposed and evaporated by heating for several tens of minutes at a temperature above 300°C and below the melting point of the brazing filler metal under reduced pressure of 1g or more or in an Ar gas atmosphere. After that, brazing is completed by heating to a temperature suitable for each brazing material, holding it for several tens of minutes, and slowly cooling it to room temperature.As a result of the above, conventional brazing methods were industrially impossible. Highly corrosion resistant Ni-
It becomes possible to braze all at once using a Cr-based brazing filler metal.

The heat exchanger uses the aforementioned stainless steel plate brazing method.

This section describes the method applied to the heat exchanger plate assembly method.

First, two stainless steel plates on which a brazing metal coating layer is provided by spraying a brazing metal suspension solution on both or one side and preheating are alternately laminated with a stainless steel plate formed and processed into a corrugated shape. Charge this material into a vacuum heating furnace and
The organic binder is decomposed and evaporated by heating for several tens of minutes under a reduced pressure of -'m+mt 1 g or more or in an Ar gas atmosphere at a temperature of 300° C. or higher and lower than the melting point of the brazing material, and the powder brazing material is brought into close contact with the interface of the stainless steel plate. Thereafter, the brazing material is heated to a temperature suitable for each brazing material, held for several tens of minutes, and slowly cooled to room temperature to complete brazing, thereby assembling a heat exchanger plate for a stainless steel heat exchanger.

Table 11 LJL4 Sen 1 Kita: A method for manufacturing surface-treated steel sheets using part of the brazing method for stainless steel sheets described above will be described.

First, a brazing material suspension fA solution whose main component is a high-temperature corrosion-resistant metal composition (e.g., 50Cr-5ON i alloy) or a highly corrosion-resistant alloy composition (e.g., Inconel 625, Hastelloy, etc.) is applied to a carbon steel plate, stainless steel plate, or After coating on both sides or one side of other metal plates, a coating layer of brazing material is applied by preheating. Number 1 in the range below the melting point of
Heat for 0 minutes to bring the solder powder into close contact with the surface of the steel plate. After that, the steel plate is heated to a temperature suitable for each brazing filler metal.
This is a surface treatment method in which a desired film is obtained by coating the surface of the base material with a brazing material by holding for a minute and slowly cooling it. Depending on the purpose and shape of the steel sheet, this manufacturing method involves removing the solvent through preheating, then slowly cooling it to room temperature, using it as a raw material for surface-treated steel sheets, and then heating it to a temperature suitable for powder brazing filler metal after processing such as cutting. It is also possible to perform surface treatment by removing and melting the brazing filler metal.

Next, examples of the present invention will be shown, but these are illustrative of the present invention and are not intended to unduly limit the present invention.

Large flame thickness 0.5mm, length 100~300mm+, width 1
Ni-Cr with an average particle size of 30 to 50 μm was coated on the surface of a stainless steel plate (SUS304) test piece with a diameter of 00 to 300 mm.
A suspension solution obtained by mixing -5i powder brazing filler metal (trade name "Niclo Blaze") in a solvent (such as trichloroethane) containing an acrylic resin-based organic binder was applied by spraying.

The amount of brazing filler metal applied was 400 g/m''.Drying temperature 8
The film thickness when the solvent was removed at 0° C. was about 50 μm.

The thus obtained pre-coated brazing material coated test piece was
Sample materials were fabricated by processing the combinations and shapes shown in Figures 4, 5, and 6.

That is, FIG. 3 shows a sample material (referred to as sample wall 1) in which a test piece 30 coated with filler metal on one side and a stainless steel plate 32 are stacked and fixed with an overlap margin of 30 nm. Figure 4 shows a stainless steel plate (SIJS304) processed into a corrugated shape between two test pieces 40.40 coated with filler metal on one side.
42 is laminated and fixed (referred to as sample material 2). Figure 5 shows a sample material (referred to as sample magnet 3) in which a test piece coated with brazing filler metal on both sides was laminated and fixed between two stainless steel plates 50.5 mm, and Figure 6 shows a carbon steel plate (SS41 ) 6'0 and a sample material (referred to as 4 for sample 1'41) coated with a brazing filler metal 62 on one side.

These sample materials were brazed in a vacuum heating furnace with a reduced pressure of about I.times.10-' Torr while the coated surface was held horizontally and the heating cycle shown in FIG. 7 was applied.

That is, after heating in the range of 500 to 900°C for about 20 minutes, it was further heated to about 1130°C (the melting temperature of the brazing material used in this sample is about 1100°C), held for about 20 minutes, and then slowly cooled.

After each sample was prepared, tensile tests were conducted on sample 11ml at two levels: room temperature and high temperature. The results are summarized in Table 1 along with the test conditions.

As can be seen from Table 1, the bonding strength was sufficient in all cases, as can be seen from the fact that the fracture occurred at the base material.

Regarding sample 11k12, when the joint state of each corrugated plate was visually inspected, no defective joints were found. Furthermore, no deformation was observed even when pressure was applied by hand. It can be seen that the material has sufficient performance as a material for heat exchanger plates for heat exchangers.

Regarding sample size 3, a micrograph (xlOO) of the cross section of the bonding interface is shown in FIG. In this example, no particular measures were taken to degas the decomposed gas from the organic binder, but as is clear from the photograph in Figure 9, overall there were few remaining bubbles, and there was no decomposition gas. It can be seen that the bonding interface between the material and the base metal is in a good bonded state with no voids, and a sound brazed state has been obtained.

Next, as for sample 1b4, Fig. 10 shows a microstructure photograph of its cross section, and the wettability of the brazing material was extremely good.
It was found that the thickness of the brazing filler metal was also uniform, and Sample 4 was further evaluated by conducting a salt spray test in which 3% saline was sprayed for 100 hours. The results are summarized in Table 2 below.

As can be seen from the results in Table 2, according to the present invention, the corrosion resistance of the metal material provided with the brazing filler metal coating layer is good, and the present invention has no problems as a surface metallizing method. I understand that.

(Effects of the Invention) As detailed above, according to a specific embodiment of the present invention, a stainless steel powder brazing material is mixed with a solvent containing an organic binder, and the mixture is sprayed onto the surface of a stainless steel tone plate. According to the present invention, the main body of the processed product is brazed by heating after processing and assembly, and according to the present invention,
Using the brazing method of the present invention, it is possible to uniformly and easily braze a wide joint area of a stainless steel plate with a stainless steel brazing filler metal, which has significant practical benefits. This makes it possible to industrially easily manufacture a stainless steel heat exchanger, and furthermore, by using the method of coating a brazing material on the surface of a steel plate according to the present invention, a surface-treated steel plate with extremely excellent corrosion resistance can be obtained. The significance of the present invention is remarkable as it enables the following.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a continuous manufacturing apparatus for pre-coated brazing metal coated metal sheets according to the present invention; FIG. 2 is an explanatory diagram of the surface state of the metal sheet according to the present invention; FIGS. 3 to 6 Figure 7 is a graph showing the heating conditions for sample preparation; Figure 8 is a cross-sectional view of the heat exchanger plate; Figure 9 is a diagram showing the overall shape of the test piece obtained in Example. Metal W4 microstructure photograph (xloo) of the bonded cross section of the test piece; and Applicant Nippon Stainless Co., Ltd. Representative Patent Attorney Akira Hirose -, ifE, /I! 1 2 Kyo wo 1 = Buto 8 Spray f1n10 U V field 1;・Lido 2nd concave 22 3 years old 24 Koso (Baishita 1 31st! 1 Hou 4 concave book 50 Steam diagram Ω 7th concave @ C- Tail 8 figure

Claims (6)

[Claims] (1) A pre-coated brazing material coated metal sheet material, characterized in that a brazing material coating layer made of an organic binder and a brazing material is provided on the surface of the metal sheet material. (2) Pre-coated brazing filler metal coating, characterized in that a brazing filler metal in which a solvent is suspended together with an organic binder is applied to the surface of a metal plate, and then the solvent is removed by preheating to form a coating layer of the brazing filler metal. Manufacturing method for metal plate materials. (3) A material to be joined is brought into contact with the surface of the pre-coated brazing material-coated metal plate material according to claim (1), and heated to a temperature of 300° C. or more and below the melting point of the brazing material in a vacuum or an inert gas atmosphere. A brazing method, characterized in that the organic binder is removed and then heated to a brazing temperature. (4) At least one set of the flat plate material, which is the pre-coated brazing metal coated metal plate material according to claim (1), and the metal plate material formed into a corrugated, corrugated or veined shape are alternately stacked and fixed, and then vacuum A method for assembling a heat exchanger plate, comprising heating to a temperature of 300° C. or higher and lower than the melting point of the brazing material under an inert gas atmosphere to remove the organic binder, and then heating to a brazing temperature. (5) The pre-coated brazing metal coated metal plate according to claim (1) and another metal plate are laminated, and then heated to a temperature of 300°C or higher and lower than the melting point of the brazing metal under vacuum or an inert gas atmosphere. A method for producing a metal clad material, the method comprising: removing the organic binder, and then heating to a brazing temperature. (6) A metal plate provided with a pre-coated brazing filler metal coating layer by the method according to claim (2) is heated to a brazing temperature to form a corrosion-resistant, heat-resistant and scale-resistant coating layer made of the brazing filler metal. A method for manufacturing a corrosion-resistant surface-coated metal material.