阅读说明：本技术 一种用于低真空环境的高温钎焊环及其制备方法 (High-temperature brazing ring for low-vacuum environment and preparation method thereof ) 是由 经敬楠 于 2021-09-15 设计创作，主要内容包括：本发明涉及钎焊材料领域,公开了一种用于低真空环境的高温钎焊环及其制备方法。该高温钎焊环包括以下原料：镍铬铁合金60～95%、单氟磷酸钠1～15%、锰粉1～6%和成形胶5～15%。本发明的高温钎焊环用于不锈钢管/板件的低真空环境钎焊,可实现高效率、高强度的焊接。本发明制备方法可解决镍基合金钎料难以成形为带、片等形状的难题,拓展了镍基钎料的使用方式。(The invention relates to the field of brazing materials, and discloses a high-temperature brazing ring used in a low-vacuum environment and a preparation method thereof. The high-temperature brazing ring comprises the following raw materials: 60-95% of nickel-chromium-iron alloy, 1-15% of sodium monofluorophosphate, 1-6% of manganese powder and 5-15% of forming glue. The high-temperature brazing ring is used for low-vacuum environment brazing of stainless steel pipes/plates, and can realize high-efficiency and high-strength welding. The preparation method of the invention can solve the problem that the nickel-based alloy brazing filler metal is difficult to form into the shapes of strips, sheets and the like, and expands the use mode of the nickel-based brazing filler metal.)

1. A high temperature brazing ring for use in a low vacuum environment, comprising: the method comprises the following raw materials: 60-95% of nickel-chromium-iron alloy, 1-15% of sodium monofluorophosphate, 1-6% of manganese powder and 5-15% of forming glue.

2. The high temperature brazing ring of claim 1, wherein: the method comprises the following raw materials: 65-90% of nickel-chromium-iron alloy, 2-14% of sodium monofluorophosphate, 2-5% of manganese powder and 6-14% of forming glue.

3. The high temperature brazing ring of claim 1, wherein: the size of the welding ring is as follows: the thickness is 0.1-4 mm, the inner diameter is 1-10 mm, and the outer diameter is 2-15 mm.

4. The high temperature brazing ring of claim 1, wherein: the nickel-chromium-iron alloy comprises the following components in percentage by mass: 55-65% of Ni, 10-30% of Cr and 20-30% of Fe.

5. The high temperature brazing ring according to claim 1, 2 or 3, wherein: the nickel-chromium-iron alloy is vacuum atomized alloy powder.

6. The high temperature brazing ring of claim 1, wherein: the manganese powder is electrolytic manganese powder.

7. The high temperature brazing ring of claim 1, wherein: the forming glue is a solution colloid which is completely decomposed and volatilized at 400-600 ℃.

8. The high temperature brazing ring of claim 7, wherein: the forming glue comprises the following components in percentage by mass: 27-31% of polyisobutene, 19-23% of terpene resin and 45-55% of butyl acetate.

9. A method of producing a high temperature brazing ring according to any one of claims 1 to 8, comprising the steps of:

the method comprises the following steps: mixing and dissolving the components of the forming glue, and filtering for later use after the components are fully dissolved;

step two: melting and cooling the nickel-chromium-iron alloy into a bar, preparing vacuum atomized alloy powder by a vacuum atomization process, and filtering the powder by a screen for later use;

step three: mixing the forming glue, the vacuum atomized alloy powder, the sodium monofluorophosphate and the manganese powder according to the proportion, stirring to prepare a paste mixture, and taking out for later use;

step four: rolling the pasty mixture prepared in the step three into a thin strip, and drying the thin strip for later use;

step five: and punching the thin strip manufactured in the fourth step into a welding ring by using a punching machine loaded with a circular ring die.

10. The method of claim 9, wherein: in the second step, the screen is a 100-200 mesh screen.

Technical Field

The invention relates to the field of brazing materials, in particular to a high-temperature brazing ring used in a low-vacuum environment and a preparation method thereof.

Background

In heat exchange devices, there is a wide range of welding between tubes/plates of stainless steel material, and such devices are generally used in high temperature, liquid, and weak corrosive environments, and therefore have high requirements on strength, sealing property, and corrosion resistance of the welded joint. The manufacturing industry commonly adopts BNi71CrSi nickel-based alloy solder to realize the connection of stainless steel pipes/plates by a high-temperature vacuum brazing technology.

Although the nickel-based alloy is widely used as a high-temperature brazing material, due to the high melting point (1452 ℃) of nickel, in order to lower the melting temperature of the nickel-based alloy, non-metallic elements such as silicon, boron, phosphorus and the like are usually added, so that the brittleness of the nickel-based alloy is increased, the processability is seriously deteriorated, and the nickel-based alloy can only be used in a powder state. When stainless steel pipes/plates are welded, particularly when the number of the stainless steel pipes is large, the nickel-based brazing material in a powder state seriously reduces the efficiency of brazing filler metal presetting.

In addition, it has been reported that heat exchanger manufacturers begin to use a low vacuum brazing process to improve production efficiency, which can significantly shorten or even eliminate the high vacuum process, and directly complete the welding process in a low vacuum environment (vacuum degree is less than or equal to 0.1 Pa). However, we find that under the condition of low vacuum, the oxide film on the surface of stainless steel is difficult to remove, and the wettability of the stainless steel by the conventional nickel-based brazing filler metal is reduced, so that the filling performance of the joint gap after welding is poor, and the strength of the joint after welding is reduced, thereby affecting the service life of the workpiece.

Disclosure of Invention

In order to solve the technical problem, the invention provides a high-temperature brazing ring used in a low vacuum environment and a preparation method thereof. The invention aims to provide a high-temperature brazing ring for a low-vacuum environment, which is used for low-vacuum environment brazing of stainless steel pipes/plates and can realize high-efficiency and high-strength welding. The second purpose of the invention is to provide a preparation method of a high-temperature brazing ring used in a low vacuum environment, which solves the problem that the nickel-based alloy brazing filler metal is difficult to form into the shapes of strips, sheets and the like, and expands the use mode of the nickel-based brazing filler metal.

The specific technical scheme of the invention is as follows:

in a first aspect, the present invention provides a high temperature brazing ring for use in a low vacuum environment, comprising the following raw materials: 60-95% of nickel-chromium-iron alloy, 1-15% of sodium monofluorophosphate, 1-6% of manganese powder and 5-15% of forming glue.

The functions of the components in the formula are as follows:

the nickel-chromium-iron alloy is melted at the brazing temperature, the joint gap is filled, and the joint connection is realized through cooling and solidification.

Sodium monofluorophosphate: the sodium monofluorophosphate used is in a powder form, has a melting point of 625 ℃, is easier to mix with the alloy powder and the forming glue compared with other fluorophosphates, and has a melting point slightly higher than the finishing temperature (600 ℃) for decomposition and volatilization of the forming glue, so that the adverse effect of the decomposition and volatilization of the forming glue on the brazing process is avoided. After the brazing temperature reaches 625 ℃, the sodium monofluorophosphate starts to melt and flow, the sodium monofluorophosphate is spread on the front edge of the surface of the joint, and with the rise of the temperature, fluoride ions generated by the decomposition of the sodium monofluorophosphate react with an oxide film on the surface of a workpiece to generate low-melting-point fluoride, so that the effect of removing an oxide film is achieved, and preparation is prepared for the spreading of subsequent alloy solution.

Manganese powder: the nickel-chromium-iron alloy serving as a welding main body of the welding ring has excellent wetting spreading performance on stainless steel, but compared with a high-vacuum environment, the oxygen content in a low-vacuum environment is remarkably increased, the wetting spreading performance of a nickel-chromium-iron alloy liquid phase is reduced, and the filling performance of a joint gap is poor. Therefore, manganese powder is added into the formula, a manganese-nickel phase diagram shows that manganese and nickel are mutually dissolved to form a solid solution, the added manganese powder can be dissolved in a molten nickel-chromium-iron alloy liquid phase in the brazing heating process, manganese is used as a strong reducing agent, dissolved oxygen can be absorbed, the wetting and spreading performance of the alloy liquid phase is improved, and the manganese can play a role in strengthening the alloy phase after the alloy liquid phase is cooled and solidified, so that the strength of a welded joint is improved. In addition, because the melting point of manganese is high (1244 ℃), most of manganese powder still exists in a powder form at the brazing temperature, so that the capillary action of a brazing gap can be enhanced, and the liquid phase alloy can fill the joint gap more fully.

The forming glue is a key substance for forming the matrix welding powder, is dissolved into a glue body at low temperature and can assist in forming. In the brazing process, the forming glue is completely decomposed and volatilized at high temperature, and no adverse effect is caused on the brazing joint.

In conclusion, the brazing filler metal solves the problem that the nickel-based alloy serving as the brazing filler metal is difficult to process into the shapes of belts, rings and the like due to brittleness, can realize quicker and more accurate brazing filler metal presetting and is convenient for automatic operation when being used for brazing pipes/plates.

Preferably, the high-temperature brazing ring comprises the following raw materials: 65-90% of nickel-chromium-iron alloy, 2-14% of sodium monofluorophosphate, 2-5% of manganese powder and 6-14% of forming glue.

Preferably, the size of the welding ring is as follows: the thickness is 0.1-4 mm, the inner diameter is 1-10 mm, and the outer diameter is 2-15 mm.

Preferably, the nickel-chromium-iron alloy comprises the following components in percentage by mass: 55-65% of Ni, 10-30% of Cr and 20-30% of Fe.

Preferably, the nickel-chromium-iron alloy is vacuum atomized alloy powder.

Preferably, the manganese powder is electrolytic manganese powder.

Preferably, the molding compound is a solution colloid which is completely decomposed and volatilized at 400-600 ℃.

Further, the forming glue comprises the following components in percentage by mass: 27-31% of polyisobutene, 19-23% of terpene resin and 45-55% of butyl acetate.

The forming glue is dissolved at low temperature to form a colloid which is a key substance for forming matrix welding powder, and the forming glue is completely decomposed and volatilized at 400-600 ℃ in the brazing process, so that no adverse effect is caused on a brazed joint.

In a second aspect, the present invention provides a method for preparing a high temperature brazing ring, comprising the steps of:

the method comprises the following steps: mixing and dissolving the components of the forming glue, and filtering for later use after the components are fully dissolved.

Step two: melting and cooling the nickel-chromium-iron alloy into a bar, preparing vacuum atomized alloy powder by a vacuum atomization process, and filtering the powder by a screen for later use.

Step three: mixing the forming glue, the vacuum atomized alloy powder, the sodium monofluorophosphate and the manganese powder according to the proportion, stirring to prepare a paste mixture, and taking out for later use.

Step four: rolling the pasty mixture prepared in the step three into a thin strip, and drying the thin strip for later use.

Step five: and punching the thin strip manufactured in the fourth step into a welding ring by using a punching machine loaded with a circular ring die.

Preferably, in the second step, the screen is a 100-200 mesh screen.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention provides a high-temperature brazing ring for a low-vacuum environment, which can realize high-efficiency and high-strength welding when used for brazing a stainless steel pipe/plate in the low-vacuum environment by optimizing the composition of the high-temperature brazing ring.

(2) The invention provides a preparation method of a high-temperature brazing ring used in a low vacuum environment, which solves the problem that a nickel-based alloy brazing filler metal is difficult to form into a strip, a sheet and the like, and expands the use mode of the nickel-based brazing filler metal.

(3) The high-temperature brazing ring can obviously reduce the brazing temperature and time, thereby improving the brazing efficiency.

Drawings

FIG. 1 is a top view of a high temperature weld ring of the present invention;

fig. 2 is a cross-sectional view a-a of fig. 1.

Detailed Description

The present invention will be further described with reference to the following examples.

General examples

A high temperature brazing ring for use in a low vacuum environment, as shown in fig. 1-2, having dimensions of: the thickness is 0.1-4 mm, the inner diameter is 1-10 mm, and the outer diameter is 2-15 mm. The high-temperature brazing ring comprises the following raw materials: 60-95% of nickel-chromium-iron alloy, 1-15% of sodium monofluorophosphate, 1-6% of manganese powder and 5-15% of forming glue. Further preferably 65-90% of nickel-chromium-iron alloy, 2-14% of sodium monofluorophosphate, 2-5% of manganese powder and 6-14% of forming glue.

The nickel-chromium-iron alloy is vacuum atomized alloy powder and comprises the following components in percentage by mass: 55-65% of Ni, 10-30% of Cr and 20-30% of Fe. The manganese powder is electrolytic manganese powder. The forming glue is a solution colloid which is completely decomposed and volatilized at 400-600 ℃, and comprises the following components in percentage by mass: 27-31% of polyisobutene, 19-23% of terpene resin and 45-55% of butyl acetate.

A preparation method of a high-temperature brazing ring comprises the following steps:

the method comprises the following steps: mixing and dissolving the components of the forming glue, and filtering for later use after the components are fully dissolved.

Step two: melting and cooling the nickel-chromium-iron alloy into a bar, preparing vacuum atomized alloy powder by a vacuum atomization process, and filtering the powder by a 100-mesh and 200-mesh screen for later use.

Step three: mixing the forming glue, the vacuum atomized alloy powder, the sodium monofluorophosphate and the manganese powder according to the proportion, stirring to prepare a paste mixture, and taking out for later use.

Step four: rolling the pasty mixture prepared in the step three into a thin strip, and drying the thin strip for later use.

Step five: and punching the thin strip manufactured in the fourth step into a welding ring by using a punching machine loaded with a circular ring die.

Example 1

A high-temperature brazing ring for a low vacuum environment comprises the following components in percentage by mass: 84% of nickel-chromium-iron alloy, 3% of sodium monofluorophosphate, 5% of electrolytic manganese powder and 8% of forming glue. The thickness of the welding ring is 0.2mm, the inner diameter is 2mm, and the outer diameter is 3 mm.

The preparation method of the high-temperature brazing ring comprises the following steps:

1. preparation of molding compound: weighing 29% of polyisobutylene, 21% of terpene resin and 50% of butyl acetate according to the mass ratio, putting into a reaction kettle, heating to 70 ℃, continuously stirring for 8 hours, taking out after full dissolution, and filtering for later use.

2. Preparing a nickel-chromium-iron alloy: weighing 60% of Ni, 15% of Cr and 25% of Fe according to the mass ratio, smelting and casting the materials into bars, then preparing alloy powder by adopting a vacuum atomization process, and filtering the alloy powder by using a 150-mesh screen for later use.

3. Mixing materials: and (3) mixing and stirring the sodium monofluorophosphate and the manganese powder obtained in the step (1) and the step (2) according to the mass ratio by adopting a stirrer to prepare a paste mixture, and taking out the mixture for later use after uniformly mixing the mixture.

4. Rolling of the thin strip: and (4) rolling the paste mixture prepared in the step (3) into a thin strip with the thickness of 0.2mm by using a roller press, and drying the thin strip for later use.

5. Preparing a welding ring: and (4) loading a punching machine with the die with the size, and punching the thin strip manufactured in the step (4) into a welding ring.

Example 2

A high-temperature brazing ring for a low vacuum environment comprises the following components in percentage by mass: 81% of nickel-chromium-iron alloy, 5% of sodium monofluorophosphate, 4% of electrolytic manganese powder and 10% of forming glue. The thickness of the welding ring is 0.8mm, the inner diameter is 5mm, and the outer diameter is 7 mm.

The method of making the nickel alloy weld ring is the same as example 1.

Example 3

A high-temperature brazing ring for a low vacuum environment comprises the following components in percentage by mass: 77% of nickel-chromium-iron alloy, 8% of sodium monofluorophosphate, 3% of electrolytic manganese powder and 12% of forming glue. The thickness of the welding ring is 2.0mm, the inner diameter is 7mm, and the outer diameter is 10 mm.

The method of making the nickel alloy weld ring is the same as example 1.

Example 4

A high-temperature brazing ring for a low vacuum environment comprises the following components in percentage by mass: 72% of nickel-chromium-iron alloy, 12% of sodium monofluorophosphate, 2% of electrolytic manganese powder and 14% of forming glue. The thickness of the welding ring is 4.0mm, the inner diameter is 10mm, and the outer diameter is 15 mm.

The method of making the nickel alloy weld ring is the same as example 1.

Comparative example 1

This comparative example is different from example 3 in that the weld ring component does not contain manganese powder: 89% of nickel-chromium-iron alloy, 1% of sodium monofluorophosphate and 10% of forming glue.

Comparative example 2

This comparative example is different from example 3 in that the weld ring component does not contain manganese powder: 87% of nickel-chromium-iron alloy, 3% of sodium monofluorophosphate and 10% of forming glue.

Comparative example 3

This comparative example is different from example 3 in that the weld ring component does not contain manganese powder: 82% of nickel-chromium-iron alloy, 8% of sodium monofluorophosphate and 10% of forming glue.

Comparative example 4

This comparative example is different from example 3 in that the weld ring component does not contain manganese powder: 80% of nickel-chromium-iron alloy, 10% of sodium monofluorophosphate and 10% of forming glue.

Comparative example 5

This comparative example is different from example 3 in that the weld ring component does not contain manganese powder: 75% of nickel-chromium-iron alloy, 15% of sodium monofluorophosphate and 10% of forming glue.

Comparative example 6

This comparative example compares to example 3 except that the weld ring component does not contain sodium monofluorophosphate: 89% of nickel-chromium-iron alloy, 1% of manganese powder and 10% of forming glue.

Comparative example 7

This comparative example compares to example 3 except that the weld ring component does not contain sodium monofluorophosphate: 87% of nickel-chromium-iron alloy, 3% of manganese powder and 10% of forming glue.

Comparative example 8

This comparative example compares to example 3 except that the weld ring component does not contain sodium monofluorophosphate: 85% of nickel-chromium-iron alloy, 5% of manganese powder and 10% of forming glue.

Comparative example 9

This comparative example compares to example 3 except that the weld ring component does not contain sodium monofluorophosphate: 83% of nickel-chromium-iron alloy, 7% of manganese powder and 10% of forming glue.

Comparative example 10

The present comparative example differs from example 3 in the weld ring composition: 88% of nickel-chromium-iron alloy, 1% of sodium monofluorophosphate, 1% of manganese powder and 10% of forming glue.

Comparative example 11

The present comparative example differs from example 3 in the weld ring composition: 74% of nickel-chromium-iron alloy, 15% of sodium monofluorophosphate, 1% of manganese powder and 10% of forming glue.

According to the specification of the bar joint test sample in GB/T11363-2008 brazing joint strength test method, 304 stainless steel bars are used as base materials, brazing rings prepared in the above examples and comparative examples are brazed under a low vacuum environment (the vacuum degree is less than or equal to 0.1Pa), different melting temperatures are set in the test, so that the optimal brazing temperature is selected, and finally the joint shear strength at the optimal brazing temperature is tested, wherein the obtained test data are shown in Table 1.

TABLE 1 braze performance test data for examples 1-4 and comparative examples 1-11 and BNi71CrSi braze

From the test data in table 1, it can be seen that the strength of the welding ring with sodium monofluorophosphate added alone in comparative examples 1-5 is not improved compared with that of the BNi71CrSi needle material, and the optimal brazing temperature is not reduced below 1200 ℃. Compared with the welding ring BNi71CrSi brazing filler metal with the manganese powder added alone in the comparative examples 6-9, the joint strength is far lower than that of the latter, and the optimal brazing temperature is higher than that of the latter, and the data of the examples 1-4 show that the joint strength and the optimal brazing temperature are obviously improved only by using the sodium monofluorophosphate and the manganese powder together, but if the two are too small (comparative example 10) or the mixture is not uniform (comparative example 11), the joint strength is still worse than that of the BNi71CrSi brazing filler metal. In addition, compared with the existing BNi71CrSi brazing filler metal which is only in a powder use form and a paste use form, the brazing ring prepared in the embodiment 1-4 is more convenient to be used for brazing stainless steel pipes/plates, the using amount of the brazing filler metal is easier to control, an automatic device can be adopted for welding ring presetting, and the production efficiency can be obviously improved.

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.