A braze coating material and method of making the same

Abstract

The application provides a brazing coating material and a preparation method thereof. The brazing coating material comprises: a brazing material, the brazing material comprises: diamond, alloy powder; compounded heat-conducting filler; and a binder, the binder is used for mixing with the powdery brazing material and the compounded heat-conducting filler to form the brazing coating material in a fluid or paste state. The brazing coating material of the application effectively improves the heat conductivity coefficient of the brazing coating material by adding the compounded heat-conducting filler, improves the heat conduction performance of the coating, effectively reduces the drying time in the preparation stage of the induction brazing coating and the induction heating heat transfer time, and reduces the production cost of the brazing coating process.

Description

Technical Field

[0001] The present invention relates to the technical field of brazing, and in particular to a brazing coating material and a preparation method thereof. Background Art

[0002] Friction and wear are among the main causes of failure and energy loss in key components of engineering equipment. Utilizing surface engineering techniques to create wear-resistant and corrosion-resistant protective coatings on component surfaces can significantly increase workpiece life, extend service life, reduce production costs, and minimize energy consumption. Diamond, as a superabrasive, possesses extremely high hardness, excellent thermal conductivity, and superior wear resistance. Metal-bonded diamond grinding tools, characterized by high bond strength, excellent formability, and long service life, can meet the requirements of high-speed grinding and ultra-precision grinding technologies. They have become essential processing tools for a variety of high-density, high-hardness, and hard and brittle materials.

[0003] Induction brazing technology is an important means of modifying and improving the properties of material surfaces. Induction brazing experiments were conducted using carbon steel and ceramic substrates, systematically studying the temperature variations of powdered and paste-based brazing coatings. The heat transfer mode and path during the brazing process were analyzed. The results show that the coating material cannot be directly heated by induction brazing. The heat source for the brazing coating temperature rise comes almost entirely from heat conduction through the steel substrate. The liquid-solid interface conducts intense heat and advances in stages, promoting the melting and spreading of the metal brazing filler metal. When the substrate is replaced with ceramic instead of conductive and induction-heatable carbon steel, the coating material can only heat up by generating its own heat. Powdered brazing coatings are in a free state, with gas between the powder particles and between the powder particles and the diamond. This makes it difficult for the heat from the substrate to be transferred to the upper layer, preventing the powder from fully melting. However, paste-based coatings with a binder added can melt rapidly during the induction process. The binder has multiple functions, including heat conduction, fluxing, and protection.

[0004] Brazed diamond wear-resistant coating technology utilizes the principles of brazing, utilizing the wetting and spreading of a liquid brazing alloy on the base metal and diamond surfaces to form a coating with special properties. Diamond brazing coating material primarily consists of diamond particles, a bonding material, and a nickel-based brazing filler metal. This paste is then applied to the surface to be brazed.

[0005] Currently, brazing coating materials generally use organic binders. After being applied to the surface, they need to be heated and dried at low temperatures before brazing coating. Generally, the more thorough the drying, the better the coating's formability. However, the long heating and drying time significantly limits the production efficiency of diamond brazing coating products and increases production costs. Summary of the Invention

[0006] To solve the above problems, the present invention provides a solder coating material and a preparation method thereof. The solder coating material of the present invention effectively improves the thermal conductivity of the solder coating material by adding a compound thermally conductive filler, improves the thermal conductivity of the coating, effectively reduces the drying time and induction heating heat transfer time in the preparation stage of induction solder coating, and reduces the production cost of the solder coating process.

[0007] Therefore, a first object of the present invention is to provide a brazing coating material.

[0008] The second object of the present invention is to provide a method for preparing a brazing coating material.

[0009] To achieve the first objective of the present invention, the technical solution of the present invention provides a brazing coating material, which includes: a brazing material, which includes: diamond, alloy powder; a compound thermally conductive filler; and a binder, which is used to mix with the powdered brazing material and the compound thermally conductive filler to form a fluid or paste-like brazing coating material.

[0010] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: In the related technology, in order to improve the formability of the coating, the drying time is 8 to 10 hours, while the induction heating process is only about 1 minute. At the same time, test results confirm that the metal brazing coating material, whether in powder or paste form, cannot be directly induction heated. During induction brazing, the coating material cannot be directly induction heated, and the heat source for the brazing coating layer to heat up comes from the substrate. The poor thermal conductivity of the brazing coating material restricts the thermal conduction efficiency of the brazing coating during induction heating, resulting in a long thermal conduction time. Existing brazing coating materials generally ignore the thermal conductivity of the brazing coating material itself. Long-term heat conduction not only reduces the brazing efficiency, but also requires the substrate to maintain a high temperature for a long time through heat conduction, which can easily cause thermal damage to the steel substrate, cause coarsening of grains, and reduce the mechanical properties of the substrate. Long-term heating leads to increased oxidation of the material, reducing the mechanical properties and connection strength between the coating and the substrate. The brazing coating material of the present invention comprises: a brazing material, which comprises diamond and alloy powder. Diamond, as a superhard abrasive, has extremely high hardness, good thermal conductivity and good wear resistance. The alloy powder combined with the diamond grinding tool has the characteristics of high bonding strength, good formability, long service life, and can meet the requirements of high-speed grinding and ultra-precision grinding technology. The brazing coating material of the present invention comprises: a binder. When an appropriate amount of the binder is added, the brazing material is fully melted. The binder has a crucial fluxing effect. However, the extremely poor thermal conductivity of the organic polymer material itself is one of the factors that restrict the heating and drying time, thereby restricting the drying efficiency. The brazing coating material of the present invention is added with a composite thermally conductive filler to effectively improve the thermal conductivity coefficient of the brazing coating material, improve the thermal conductivity of the coating, greatly reduce the drying time in the brazing coating preparation stage, and reduce the production cost of the brazing coating process.

[0011] Furthermore, the diamond particle size is 200 μm-300 μm.

[0012] The smaller the diamond particle size, the larger its specific surface area, and the easier it is to be burned in the brazing coating material. Those skilled in the art can select the diamond particle size according to the actual usage based on the content of the present invention.

[0013] In one technical solution of the present invention, the composite thermally conductive filler includes boron nitride and carbon nanotubes.

[0014] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: the composite thermal conductive filler of the present invention includes boron nitride and carbon nanotubes, and the thermal conductivity of the adhesive and the brazing coating material is effectively improved by adding carbon nanotubes and boron nitride materials with high thermal conductivity.

[0015] In one technical solution of the present invention, the carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant; and / or the boron nitride includes hexagonal boron nitride modified with epoxy-functionalized silane.

[0016] Further, the epoxy-functional silane includes γ-(2,3-epoxypropoxy)propyltrimethoxysilane, ie, KH560.

[0017] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the boron nitride of the present invention includes hexagonal boron nitride modified with epoxy-functionalized silane, and the hexagonal boron nitride is combined with carbon nanotubes to improve the thermal conductivity of the brazing coating material. By modifying the hexagonal boron nitride with epoxy-functionalized silane, the dispersibility, interfacial adhesion, thermal conductivity, stability and strength of the hexagonal boron nitride can be improved to varying degrees.

[0018] Furthermore, the weakly alkaline surfactant includes sodium cholate.

[0019] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the carbon nanotubes of the present invention include single-walled carbon nanotubes activated by a weakly alkaline surfactant, and the single-walled carbon nanotubes have a high thermal conductivity of 6000W / m·K. In addition, by selecting a weakly alkaline surfactant, the oxidation of the brazing coating material during storage and use can be reduced, and the dispersion stability of the filler after mixing can also be improved.

[0020] In one technical solution of the present invention, the binder includes: any one of polyethylene oxide and polyethylene glycol.

[0021] Compared with existing technologies, this technical solution achieves the following technical benefits: After adding an appropriate amount of binder, the solder fully melts, and the binder plays a crucial role in fluxing. The binder of this invention utilizes a crystalline binder with a high thermal conductivity. Furthermore, the combination of polyethylene oxide and polyethylene glycol with the boron nitride and carbon nanotubes in the solder coating material improves the thermal conductivity of the binder and the solder coating material, significantly reducing drying time during the solder coating preparation stage and production costs.

[0022] In one technical solution of the present invention, the alloy powder comprises: any one of nickel-based alloy powder, copper-clad iron powder and titanium-based alloy powder or a mixture thereof.

[0023] Furthermore, the average particle size of the nickel-based alloy powder is 20 μm to 50 μm.

[0024] Furthermore, the titanium-based alloy powder includes TiH2 powder.

[0025] Compared with the existing technology, the technical effects achieved by adopting this technical solution are as follows: in the brazing coating material of the present invention, the nickel-based alloy powder can effectively improve the wear resistance and overall performance of the coating, especially enhance the bonding strength, improve the coating structure, enhance the high temperature resistance, enhance the corrosion resistance and decorativeness, thereby improving the processing efficiency of the brazing coating material, and it is relatively friendly to the environment; during the brazing coating process, the melting point of the copper-clad iron powder is higher than that of the nickel-based alloy powder, so that the coating can be nearly semi-solid formed, the iron does not contact the diamond, and excessive thermal damage to the diamond is avoided; the titanium-based alloy powder improves the shear strength of the brazed joint, which is crucial to the connection strength of the brazing coating material, and it can react with boron nitride and carbon nanotubes in the brazing coating stage to generate TiC and TiN reinforcement phases, further improving the comprehensive performance of the brazing coating.

[0026] In one technical solution of the present invention, when the alloy powder includes copper-clad iron powder, the copper-clad iron powder has a core-shell structure, and the copper-clad iron powder includes: a copper alloy shell structure, the copper alloy shell structure includes: Ni0wt%-10wt%, and the balance is copper; an iron-based alloy powder core structure, and the iron-based alloy powder core structure includes: Fe50wt%-55wt%, Ni25wt%-30wt%, Cr10wt%-15wt%, Si2.5wt%-3.5wt%, and B1.5wt%-2.5wt%.

[0027] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: since the copper-clad iron powder of the present invention is covered with a layer of copper on its surface, it can effectively improve the fluidity and filling property of the alloy powder, solve the problems of uneven structure and component segregation, and thus improve the quality of the welded joint. In addition, the present invention uses copper to isolate Fe from diamond, thereby reducing diamond graphitization. The related technologies all belong to metal plating on the surface of diamond, while the present invention is metal plating on metal powder, which plays the role of isolating diamond. Fe easily graphitizes diamond, so Cu is plated, and by specifically limiting the metal element content of the copper alloy shell structure and the iron-based alloy powder core structure, more flexibility is provided for the application of brazing coating materials. In addition, the cost of iron powder is relatively low, which helps to reduce production costs and improve the cost performance of products, and is of great significance for improving the competitiveness of products.

[0028] To achieve the second purpose of the present invention, the technical solution of the present invention provides a method for preparing a brazing coating material, comprising: S10, adding a binder to water, stirring evenly, adding carbon nanotubes, mixing evenly, adding boron nitride, and mixing evenly to obtain a mixed solution; S20, mixing diamond and alloy powder evenly to obtain a mixed powder; S30, adding the mixed powder to the mixed solution, adjusting the viscosity, and obtaining a brazing coating material.

[0029] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the preparation method of the brazing coating material of the present invention improves the thermal conductivity of the binder and the brazing coating material by adding a composite thermal conductive filler including boron nitride and carbon nanotubes to the brazing coating material, effectively reduces the heating time of the substrate during the brazing coating process, improves the limitations of the alloy powder in the application of the brazing coating material, reduces the graphitization and damage of the diamond during the alloy powder brazing coating process, and is of great significance for improving the brazing coating performance of the brazing coating material and reducing the cost.

[0030] In one technical solution of the present invention, when the carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant, the activated single-walled carbon nanotubes are obtained by uniformly mixing the single-walled carbon nanotubes with the weakly alkaline surfactant, and then sequentially performing centrifugal precipitation and drying treatment to obtain the activated single-walled carbon nanotubes.

[0031] Furthermore, the mixing is carried out by ultrasonic shaking for 12 hours to 15 hours.

[0032] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the present invention activates single-walled carbon nanotubes through a weakly alkaline surfactant, thereby reducing the oxidation of single-walled carbon nanotubes during storage and use of brazing coating materials.

[0033] In one technical solution of the present invention, when the boron nitride is hexagonal boron nitride modified with epoxy-functionalized silane, the modified hexagonal boron nitride is obtained by the following method: S11, compounding the hexagonal boron nitride with epoxy-functionalized silane to obtain a compounded powder, adding the compounded powder to an organic solvent, stirring evenly, adding alkali solution, and sequentially performing heating treatment, centrifugal precipitation treatment, and drying and grinding treatment to obtain a mixed powder; S12, adding epoxy-functionalized silane to water, hydrolyzing it, adding the mixed powder, and sequentially performing heating and stirring, filtering, washing, and drying to obtain the modified hexagonal boron nitride.

[0034] Further, in S11, hexagonal boron nitride and epoxy-functionalized silane are compounded in a mass ratio of 2:1; and / or in S11, the stirring is ultrasonic oscillation, and the time is 15h-20h; and / or in S11, the concentration of the alkali solution is 150g / L-200g / L; and / or in S11, the temperature of the heating treatment is 100℃-150℃, and the time is 24h-48h; and / or in S12, the mass fraction of the epoxy-functionalized silane is 0.5%; and / or in S12, the hydrolysis treatment is ultrasonic oscillation, and the time is 10min-20min; and / or in S12, the temperature of the heating and stirring is 70℃-100℃, and magnetic stirring is performed simultaneously with ultrasonic oscillation, and the time is 15h-30h.

[0035] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: the present invention modifies hexagonal boron nitride through epoxy-functionalized silane, which not only improves its compatibility and interaction, but also helps to improve the mechanical properties of the brazing coating and further improves the thermal conductivity of the brazing coating material.

[0036] In one technical solution of the present invention, in S10, the mixing is carried out by ultrasonic oscillation for 10 minutes to 20 minutes; and / or in S10, the mass fraction of the binder is 5% to 8%; and / or in S10, the mass fraction of the carbon nanotubes is 4% to 7%; and / or in S10, the mass fraction of the boron nitride is 5% to 10%; and / or in S20, when the alloy powder includes at least two of nickel-based alloy powder, copper-clad iron powder and titanium-based alloy powder, the added diamond and alloy powder need to be mixed evenly in pairs; and / or in S30, the viscosity is adjusted to 200Pa·s-600Pa·s.

[0037] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the present invention prepares the brazing coating material by specifically setting the conditions of each reaction step in the preparation method of the brazing coating material, especially in S20, the powders are mixed evenly in pairs and then another alloy powder is added, which effectively prevents the agglomeration of the mixed powders, which is of great significance to the uniformity of the brazing coating material. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0039] An embodiment of the present invention provides a brazing coating material, which includes: a brazing material, which includes: diamond, alloy powder; a compound thermally conductive filler; and a binder, which is used to mix with the powdered brazing material and the compound thermally conductive filler to form a fluid or paste-like brazing coating material.

[0040] In related technologies, in order to improve the formability of the coating, the drying time is 8 to 10 hours, while the induction heating process is only about 1 minute. At the same time, test results confirm that metal brazing coating materials, whether in powder or paste form, cannot be directly induction heated. During induction brazing, the coating material cannot be directly induction heated, and the heat source for the brazing coating layer to heat up comes from the substrate. The poor thermal conductivity of the brazing coating material restricts the thermal conduction efficiency of the brazing coating during induction heating, resulting in a longer thermal conduction time. Existing brazing coating materials generally ignore the thermal conductivity of the brazing coating material itself. Long-term heat conduction not only reduces the brazing efficiency, but also requires the substrate to maintain a high temperature for a long time through heat conduction, which can easily cause thermal damage to the steel substrate, cause coarse grains, and reduce the mechanical properties of the substrate. Long-term heating leads to an increase in the degree of oxidation of the material, which reduces the mechanical properties and connection strength of the coating and the substrate. The brazing coating material of the present invention comprises: a brazing material, which comprises diamond and alloy powder. Diamond, as a superhard abrasive, has extremely high hardness, good thermal conductivity and good wear resistance. The alloy powder combined with the diamond grinding tool has the characteristics of high bonding strength, good formability, long service life, and can meet the requirements of high-speed grinding and ultra-precision grinding technology. The brazing coating material of the present invention comprises: a binder. When an appropriate amount of the binder is added, the brazing material is fully melted. The binder has a crucial fluxing effect. However, the extremely poor thermal conductivity of the organic polymer material itself is one of the factors that restrict the heating and drying time, thereby restricting the drying efficiency. The brazing coating material of the present invention is added with a composite thermally conductive filler to effectively improve the thermal conductivity coefficient of the brazing coating material, improve the thermal conductivity of the coating, greatly reduce the drying time in the brazing coating preparation stage, and reduce the production cost of the brazing coating process.

[0041] For example, the diamond particle size is 200 μm-300 μm.

[0042] The smaller the diamond particle size, the larger its specific surface area, and the easier it is to be burned in the brazing coating material. Those skilled in the art can select the diamond particle size according to the actual usage based on the content of the present invention.

[0043] Specifically, in the embodiment of the present invention, the composite thermal conductive filler includes boron nitride and carbon nanotubes.

[0044] The composite heat-conductive filler of the present invention comprises boron nitride and carbon nanotubes. By adding carbon nanotubes and boron nitride materials with high thermal conductivity, the thermal conductivity of the adhesive and the brazing coating material is effectively improved.

[0045] Specifically, in the embodiments of the present invention, the carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant; and / or the boron nitride includes hexagonal boron nitride modified with epoxy-functionalized silane.

[0046] By way of example, epoxy-functional silanes include gamma-(2,3-glycidoxy)propyltrimethoxysilane, ie, KH560.

[0047] The boron nitride of the present invention includes hexagonal boron nitride modified with epoxy-functionalized silane. The hexagonal boron nitride is combined with carbon nanotubes to improve the thermal conductivity of the brazing coating material. By modifying the hexagonal boron nitride with epoxy-functionalized silane, the dispersibility, interfacial adhesion, thermal conductivity, stability and strength of the hexagonal boron nitride can be improved to varying degrees.

[0048] By way of example, weakly alkaline surfactants include sodium cholate.

[0049] The carbon nanotubes of the present invention include single-walled carbon nanotubes activated by a weakly alkaline surfactant. The single-walled carbon nanotubes have a high thermal conductivity of 6000 W / m·K. The use of a weakly alkaline surfactant can reduce the oxidation of the brazing coating material during storage and use, and can also improve the dispersion stability of the brazing filler after mixing.

[0050] Specifically, in the embodiment of the present invention, the binder includes: any one of polyethylene oxide and polyethylene glycol.

[0051] After adding an appropriate amount of binder, the solder fully melts, and the binder plays a crucial role in fluxing. The present invention utilizes a crystalline binder with a high thermal conductivity. The combination of polyethylene oxide and polyethylene glycol with the boron nitride and carbon nanotubes in the brazing coating material improves the thermal conductivity of the binder and the brazing coating material, significantly reducing drying time during the brazing coating preparation phase and the production cost of the brazing coating process.

[0052] Specifically, the alloy powder in the embodiment of the present invention includes: any one of nickel-based alloy powder, copper-clad iron powder and titanium-based alloy powder, or a mixture thereof.

[0053] For example, the average particle size of the nickel-based alloy powder is 20 μm to 50 μm.

[0054] For example, titanium-based alloy powder includes TiH2 powder

[0055] In the brazing coating material of the present invention, the nickel-based alloy powder can effectively improve the wear resistance and overall performance of the coating, especially enhance the bonding strength, improve the coating structure, enhance the high-temperature resistance, enhance the corrosion resistance and decorative properties, thereby improving the processing efficiency of the brazing coating material, and the material is relatively environmentally friendly. During the brazing coating process, the melting point of the copper-clad iron powder is higher than that of the nickel-based alloy powder, so that the coating is nearly semi-solid and the iron does not contact the diamond, thereby avoiding excessive thermal damage to the diamond. The titanium-based alloy powder improves the shear strength of the brazed joint, which is crucial to the connection strength of the brazing coating material. In addition, the titanium-based alloy powder can react with boron nitride and carbon nanotubes during the brazing coating stage to generate TiC and TiN reinforcement phases, further improving the comprehensive performance of the brazing coating.

[0056] Specifically, in the embodiment of the present invention, when the alloy powder includes copper-clad iron powder, the copper-clad iron powder is a core-shell structure, and the copper-clad iron powder includes: a copper alloy shell structure, the copper alloy shell structure includes: Ni0wt%-10wt%, and the balance is copper; an iron-based alloy powder core structure, and the iron-based alloy powder core structure includes: Fe50wt%-55wt%, Ni25wt%-30wt%, Cr10wt%-15wt%, Si2.5wt%-3.5wt%, and B1.5wt%-2.5wt%.

[0057] The copper-clad iron powder of the present invention is covered with a layer of copper on its surface, which can effectively improve the fluidity and filling properties of the alloy powder, solve the problems of uneven structure and component segregation, and thus improve the quality of the welded joint. In addition, the present invention uses copper to isolate Fe from diamond, thereby reducing diamond graphitization. The related technologies all involve metal plating on the diamond surface, while the present invention is metal plating on metal powder to isolate the diamond. Fe easily causes diamond graphitization, so Cu is plated. By specifically limiting the metal element content of the copper alloy shell structure and the iron-based alloy powder core structure, more flexibility is provided for the application of the brazing coating material. In addition, the iron powder has a low cost, which helps to reduce production costs and improve the cost-effectiveness of the product, and is of great significance for improving the competitiveness of the product.

[0058] In some embodiments of the embodiments of the present application, the embodiments of the present invention provide a method for preparing a brazing coating material, including: S10, adding a binder to water, stirring evenly, adding carbon nanotubes, mixing evenly, adding boron nitride, and mixing evenly to obtain a mixed solution; S20, mixing diamond and alloy powder evenly to obtain a mixed powder; S30, adding the mixed powder to the mixed solution, adjusting the viscosity, and obtaining a brazing coating material.

[0059] The preparation method of the brazing coating material of the present invention improves the thermal conductivity of the binder and the brazing coating material by adding a composite thermal conductive filler including boron nitride and carbon nanotubes to the brazing coating material, effectively reduces the heating time of the substrate during the brazing coating process, improves the limitations of the alloy powder in the application of the brazing coating material, and reduces the graphitization and damage of the diamond during the brazing coating process of the alloy powder. It is of great significance for improving the brazing coating performance of the brazing coating material and reducing the cost.

[0060] Specifically, in an embodiment of the present invention, when the carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant, the activated single-walled carbon nanotubes are obtained by uniformly mixing the single-walled carbon nanotubes and the weakly alkaline surfactant, and then sequentially performing centrifugal precipitation and drying treatment to obtain the activated single-walled carbon nanotubes.

[0061] For example, the mixing is carried out by ultrasonic shaking for 12 hours to 15 hours.

[0062] The invention activates the single-walled carbon nanotubes through a weakly alkaline surfactant, thereby reducing the oxidation of the single-walled carbon nanotubes during storage and use of the brazing coating material.

[0063] Specifically, in the embodiment of the present invention, when the boron nitride is hexagonal boron nitride modified with epoxy-functionalized silane, the modified hexagonal boron nitride is obtained by the following method: S11, compounding hexagonal boron nitride with epoxy-functionalized silane to obtain a compounded powder, adding the compounded powder to an organic solvent, stirring evenly, adding alkali solution, and sequentially performing heating treatment, centrifugal precipitation treatment, and drying and grinding treatment to obtain a mixed powder; S12, adding epoxy-functionalized silane to water, after hydrolysis treatment, adding the mixed powder, and sequentially performing heating and stirring, filtering, washing, and drying to obtain modified hexagonal boron nitride.

[0064] For example, in S11, hexagonal boron nitride and epoxy-functionalized silane are compounded in a mass ratio of 2:1; and / or in S11, the stirring is ultrasonic oscillation, and the time is 15h-20h; and / or in S11, the concentration of the alkali solution is 150g / L-200g / L; and / or in S11, the temperature of the heating treatment is 100℃-150℃, and the time is 24h-48h; and / or in S12, the mass fraction of the epoxy-functionalized silane is 0.5%; and / or in S12, the hydrolysis treatment is ultrasonic oscillation, and the time is 10min-20min; and / or in S12, the temperature of the heating and stirring is 70℃-100℃, and magnetic stirring is performed simultaneously with ultrasonic oscillation, and the time is 15h-30h.

[0065] The present invention modifies hexagonal boron nitride by epoxy-functionalized silane, which not only improves its compatibility and interaction, but also helps to enhance the corrosion resistance of the brazing coating material, improves the physical properties and mechanical strength to enhance the mechanical properties of the brazing coating, and further enhances the thermal conductivity of the brazing coating material.

[0066] Specifically, in an embodiment of the present invention, in S10, the mixing is uniformly performed by ultrasonic oscillation for 10 minutes to 20 minutes; and / or in S10, the mass fraction of the binder is 5% to 8%; and / or in S10, the mass fraction of the carbon nanotubes is 4% to 7%; and / or in S10, the mass fraction of boron nitride is 5% to 10%; and / or in S20, when the alloy powder includes at least two of nickel-based alloy powder, copper-clad iron powder and titanium-based alloy powder, the added diamond and alloy powder need to be uniformly mixed in pairs; and / or in S30, the viscosity is adjusted to 200Pa·s-600Pa·s.

[0067] The present invention specifically prepares the brazing coating material by setting the conditions of each reaction step in the preparation method of the brazing coating material. In particular, in S20, the powders are mixed evenly in pairs before adding another alloy powder, which effectively prevents the agglomeration of the mixed powders, which is of great significance to the uniformity of the brazing coating material.

[0068] [Example 1]

[0069] S10, adding 5% by mass of polyethylene oxide to water, stirring evenly with a magnetic stirrer, adding 4% by mass of carbon nanotubes, ultrasonically shaking for 10 minutes, adding 5% by mass of boron nitride, and ultrasonically shaking for 15 minutes to obtain a mixed solution;

[0070] S20, uniformly mixing nickel-based brazing filler metal powder and copper-clad iron powder in a mixer at a mass ratio of 1:1 to obtain a first mixed powder, uniformly mixing diamond and the mixed powder in a mixer at a mass ratio of 1:9 to obtain a second mixed powder, adding 1% TiH2 to the second mixed powder, and uniformly mixing in a mixer to obtain a mixed powder;

[0071] S30, adding the mixed powder to the mixed solution, adjusting the viscosity to 200 Pa·s, and obtaining a brazing coating material.

[0072] [Example 2]

[0073] S10, adding 7% by mass of polyethylene oxide to water, stirring evenly with a magnetic stirrer, adding 6% by mass of carbon nanotubes, ultrasonically shaking for 10 minutes, adding 8% by mass of boron nitride, and ultrasonically shaking for 10 minutes to obtain a mixed solution;

[0074] S20, uniformly mixing nickel-based brazing filler metal powder and copper-clad iron powder in a mixer at a mass ratio of 2:1 to obtain a first mixed powder, uniformly mixing diamond and the mixed powder in a mixer at a mass ratio of 1:3 to obtain a second mixed powder, adding 3% TiH2 to the second mixed powder, and uniformly mixing in a mixer to obtain a mixed powder;

[0075] S30, adding the mixed powder to the mixed solution and adjusting the viscosity to 400 Pa·s to obtain a brazing coating material;

[0076] Wherein, when the carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant, the activated single-walled carbon nanotubes are obtained by the following method:

[0077] The carbon nanotubes were mixed with an aqueous solution of sodium cholate and ultrasonically dispersed for 13 hours, followed by centrifugal precipitation and drying to obtain activated single-walled carbon nanotubes.

[0078] When the boron nitride is epoxy-functional silane-modified hexagonal boron nitride, the modified hexagonal boron nitride is obtained by the following method:

[0079] S11. Compound hexagonal boron nitride and epoxy-functional silane in a mass ratio of 2:1 to obtain a compounded powder. 20 g of the compounded powder was added to isopropanol, ultrasonically shaken in a water bath for 20 h, and a 150 g / L NaOH solution was added. The mixture was heated at a constant temperature of 100° C. for 24 h, and then the solution was removed and centrifuged and dried and ground to obtain a mixed powder.

[0080] S12. Add 0.5% by mass of epoxy-functionalized silane into water, ultrasonically vibrate for 15 minutes for hydrolysis treatment, add the mixed powder, ultrasonically vibrate at 90° C. and magnetically stir for 24 hours, filter, wash, and dry in sequence to obtain modified hexagonal boron nitride.

[0081] [Example 3]

[0082] S10, adding 8% by mass of polyethylene oxide to water, stirring evenly with a magnetic stirrer, adding 7% by mass of carbon nanotubes, ultrasonically shaking for 15 minutes, adding 10% by mass of boron nitride, and ultrasonically shaking for 15 minutes to obtain a mixed solution;

[0083] S20, uniformly mixing nickel-based brazing filler metal powder and copper-clad iron powder in a mixer at a mass ratio of 2:1 to obtain a first mixed powder, uniformly mixing diamond and the mixed powder in a mixer at a mass ratio of 1:4 to obtain a second mixed powder, adding 5% TiH2 to the second mixed powder, and uniformly mixing in a mixer to obtain a mixed powder;

[0084] S30, adding the mixed powder to the mixed solution and adjusting the viscosity to 600 Pa·s to obtain a brazing coating material;

[0085] Wherein, when the carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant, the activated single-walled carbon nanotubes are obtained by the following method:

[0086] The carbon nanotubes were mixed with an aqueous solution of sodium cholate and subjected to ultrasonic dispersion for 15 hours, followed by centrifugal precipitation and drying to obtain activated single-walled carbon nanotubes;

[0087] When the boron nitride is epoxy-functional silane-modified hexagonal boron nitride, the modified hexagonal boron nitride is obtained by the following method:

[0088] S11. Compound hexagonal boron nitride and epoxy-functional silane in a mass ratio of 2:1 to obtain a compounded powder. 20 g of the compounded powder was added to isopropanol, ultrasonically shaken in a water bath for 15 h, and a 200 g / L NaOH solution was added. The mixture was heated at a constant temperature of 120° C. for 48 h, and then the solution was removed and centrifuged and dried and ground to obtain a mixed powder.

[0089] S12. Add 0.5% by mass of epoxy-functionalized silane into water, ultrasonically vibrate for 15 minutes for hydrolysis treatment, add the mixed powder, ultrasonically vibrate at 90° C. and magnetically stir for 24 hours, filter, wash, and dry in sequence to obtain modified hexagonal boron nitride.

[0090] [Comparative Example 1]

[0091] Refer to Example 1, except that no composite thermal conductive material is added.

[0092] [Comparative Example 2]

[0093] Refer to Example 2, except that no composite thermal conductive material is added.

[0094]

[0095] It can be seen from the above experimental data that the solder coating material of the present invention effectively improves the thermal conductivity of the solder coating material by adding compound thermally conductive fillers, improves the thermal conductivity of the coating, effectively reduces the drying time and induction heating heat transfer time in the preparation stage of induction solder coating, and reduces the production cost of the solder coating process.

[0096] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0097] The writing methods of "S10", "S20" and "S30" in this specification are for the convenience of describing the embodiments of the present invention. The present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the order of the specific embodiments written in the above manner.

[0098] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A brazing coating material, characterized in that: The brazing coating material comprises: Brazing material, said brazing material comprising: diamond, alloy powder; Compound thermal conductive filler; A binder, the binder being used to be mixed with the brazing material and the compound thermally conductive filler to form the brazing coating material in a fluid or paste form; The alloy powder comprises: any one of nickel-based alloy powder, copper-clad iron powder and titanium-based alloy powder or a mixture thereof; In the case where the alloy powder includes copper-clad iron powder, the copper-clad iron powder has a core-shell structure, and the copper-clad iron powder includes: A copper alloy shell structure, comprising: Ni 0wt%-10wt%, with the balance being copper; The iron-based alloy powder core structure comprises: 50wt%-55wt% Fe, 25wt%-30wt% Ni, 10wt%-15wt% Cr, 2.5wt%-3.5wt% Si, and 1.5wt%-2.5wt% B.

2. The brazing coating material according to claim 1, wherein The composite thermal conductive filler includes boron nitride and carbon nanotubes.

3. The brazing coating material according to claim 2, wherein The carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant; and / or The boron nitride includes epoxy-functional silane-modified hexagonal boron nitride.

4. The brazing coating material according to claim 1, wherein The binder includes any one of polyethylene oxide and polyethylene glycol.

5. A method for preparing a brazing coating material, characterized in that: The preparation method is used to prepare the brazing coating material according to any one of claims 1 to 4, and the preparation method comprises: S10, adding a binder to water, stirring evenly, adding carbon nanotubes, mixing evenly, adding boron nitride, and mixing evenly to obtain a mixed solution; S20, mixing the diamond and alloy powder uniformly to obtain a mixed powder; S30, adding the mixed powder to the mixed solution, adjusting the viscosity, and obtaining the brazing coating material.

6. The preparation method according to claim 5, characterized in that When the carbon nanotubes include single-walled carbon nanotubes activated by a weakly alkaline surfactant, the activated single-walled carbon nanotubes are obtained by the following method: After the single-walled carbon nanotubes and the weak alkaline surfactant are uniformly mixed, centrifugal precipitation and drying are sequentially performed to obtain the activated single-walled carbon nanotubes.

7. The preparation method according to claim 6, characterized in that When the boron nitride is epoxy-functionalized silane-modified hexagonal boron nitride, the modified hexagonal boron nitride is obtained by the following method: S11, compounding hexagonal boron nitride and epoxy-functional silane to obtain a compound powder, adding the compound powder to an organic solvent, stirring evenly, adding alkali solution, and sequentially performing heating treatment, centrifugal precipitation treatment, and drying and grinding treatment to obtain a mixed powder; S12, adding epoxy functional silane to water, hydrolyzing it, adding the mixed powder, heating and stirring in sequence Stirring, filtering, washing and drying to obtain the modified hexagonal boron nitride.

8. The preparation method according to claim 7, characterized in that In said S10, the uniform mixing is performed by ultrasonic oscillation for 10-20 minutes; and / or In said S10, the mass fraction of said binder is 5%-8%; and / or In said S10, the mass fraction of said carbon nanotubes is 4%-7%; and / or In the S10, the mass fraction of the boron nitride is 5%-10%; and / or In said S20, when said alloy powder comprises at least two of: nickel-based alloy powder, copper-clad iron powder and titanium-based alloy powder, said diamond and alloy powders need to be mixed evenly in pairs; and / or In the S30 , the viscosity is adjusted to 200 Pa·s-600 Pa·s.

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