A particle-reinforced solder paste, its preparation method and application

Abstract

The present invention provides a particle-reinforced solder paste, a preparation method thereof, and an application, relating to the technical field of brazing. Specifically, the solder paste includes a filler metal, a brazing flux, and granular cemented carbide; wherein, the cemented carbide includes tungsten carbide. The present invention has different advantages before welding, during welding, and after welding by using cemented carbide particles as components of the solder paste; before welding, the cemented carbide particles play a role in skeleton support and ensure that the filler metal and brazing flux components are not easily extruded; during welding, the welding gap is ensured by high-diameter cemented carbide particles, thereby facilitating the discharge of impurities such as welding slag; after welding, the cemented carbide particles are evenly dispersed in the weld seam, effectively combined with the cemented carbide workpiece to be welded and the filler metal, forming a "pinning" phenomenon, and greatly improving the welding strength. In addition, the preparation method of the solder paste of the present invention is simple and easy to implement, has low cost, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of brazing, and more particularly, to a particle-reinforced solder paste, a preparation method thereof, and an application thereof. Background Art

[0002] Solder paste is a paste formed by mixing alloy solder powder, flux, and optional functional additives, and has a certain viscosity and good thixotropy. Solder paste is a homogeneous and stable mixture. After the solder paste is adhered to a predetermined position of a workpiece to be soldered, when the solder paste is heated to a certain temperature, as the alloy solder powder melts, the solder paste presents a fluid state, and after cooling, a weld is formed between the workpieces to be soldered.

[0003] In the process of brazing hard alloy tools, copper-based brazing filler metals, silver-based brazing filler metals, etc. are widely used due to their low brazing temperature and high welding strength; and solder paste can realize the synergistic effect of solder (brazing filler metal) and flux (brazing flux) and realize quantitative, positioning, and timed mixing and addition, and has the advantages of not being restricted by the shape of the weld, etc., so it is widely used. However, traditional solder paste is easily extruded or flowed out during assembly or welding, resulting in an unfilled weld or lack of soldering; at the same time, the solder slag generated during welding and the residue generated by the binder are not easily discharged, resulting in welding defects and reduced welding strength.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The first object of the present invention is to provide a particle-reinforced solder paste to solve the technical problems of unfilled welds or lack of soldering easily caused by high fluidity and thixotropy of existing solder paste, and at the same time solve the technical problem of low welding strength caused by the difficulty in discharging residues such as solder slag generated during the welding process. To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0006] A particle-reinforced solder paste, the particle-reinforced solder paste comprising a brazing filler metal, a brazing flux, and particulate cemented carbide; wherein, the cemented carbide comprises tungsten carbide.

[0007] Preferably, the particle-reinforced solder paste comprises 40 to 80 parts of brazing filler metal, 5 to 25 parts of brazing flux, and 0.1 to 5 parts of particulate cemented carbide.

[0008] Preferably, the cemented carbide further comprises at least one of titanium carbide, tantalum carbide, and niobium carbide; more preferably, the grade of the cemented carbide comprises at least one of YG, YT, or YW.

[0009] Preferably, the particle size of the cemented carbide is 0.03 mm to 0.5 mm.

[0010] Preferably, the solder includes at least one of a silver-based solder, a copper-based solder, a nickel-based solder, a cobalt-based solder and a palladium-based solder; more preferably, the solder includes one of a silver-based solder or a copper-based solder;

[0011] Further preferably, the silver-based solder includes the following elements: Ag, Cu, Zn, Ni, Mn, Co and Si; specifically, the silver-based solder includes: Cu 10% to 60%, Zn 10% to 40%, Ni 0.1% to 8%, Mn 0.1% to 8%, Co0.1% to 2%, Si 0.01% to 1%, and the balance is Ag; and the sum of the weight percentages of the elements in the silver-based solder is 100%;

[0012] Further preferably, the copper-based solder comprises the following elements: Cu, Zn, Ni, Mn, Co, Si, Fe and P; specifically, the copper-based solder comprises: Zn 20%-60%, Ni 0.5%-25%, Mn 0.5%-25%, Co 0.1%-15%, Si 0.1%-1%, Fe 0.1%-5%, P 0.1%-2%, and the remainder is Cu; and the sum of the weight percentages of each element in the copper-based solder is 100%.

[0013] Preferably, the brazing agent includes at least one of potassium fluoride, calcium fluoride, boric anhydride, boric acid, potassium fluoroborate, potassium borate and dehydrated borax.

[0014] Preferably, the particle-enhanced solder paste further comprises 8 to 30 parts of a binder; more preferably, the binder comprises at least one of vaseline, polyisobutylene and polypropylene carbonate.

[0015] The second object of the present invention is to provide a method for preparing the particle-enhanced solder paste, which is simple and easy to implement and is conducive to mass industrial production. In order to achieve the above object of the present invention, the following technical scheme is specially adopted:

[0016] The preparation method of the particle enhanced solder paste comprises the following steps: fully mixing the components to obtain the solder paste.

[0017] Preferably, before the mixing, the method further comprises: pre-treating the solder and the flux until the solder and the flux are in powder form.

[0018] The third object of the present invention is to provide an application of the particle-enhanced solder paste. Specifically, it relates to the use of the particle-enhanced solder paste in brazing;

[0019] Preferably, the particle-enhanced solder paste is used for welding workpieces containing cemented carbide.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The particle-reinforced solder paste of the present invention is mixed with solder, flux and cemented carbide particles at the same time. Before welding, the cemented carbide particles play a role in skeleton support and ensure that the solder and flux components are not easily extruded; during welding, the support of the cemented carbide particles with large particle size ensures the welding gap, thus facilitating the discharge of substances such as welding slag and binder residues; after welding, the cemented carbide particles are uniformly dispersed in the weld seam, forming an effective bond with the cemented carbide workpiece to be welded and the solder, forming a "pinning" phenomenon, which greatly improves the welding strength. Specific embodiments

[0022] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, not all embodiments, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0023] A particle-reinforced solder paste, the particle-reinforced solder paste comprising solder, flux and particulate cemented carbide; wherein the cemented carbide comprises tungsten carbide.

[0024] As a preferred embodiment, the weight parts of each component in the particle-reinforced solder paste include but are not limited to the following parameter values, or the range formed by the following parameter values: solder: 40, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, 80 (parts); flux: 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 (parts); particulate cemented carbide: 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 (parts).

[0025] As a preferred embodiment, the grades of the cemented carbide include at least one of YG, YT or YW; specifically, YG-type cemented carbide, i.e., tungsten-cobalt cemented carbide, mainly consists of the hardening phase tungsten carbide and the bonding metal cobalt, and the optional grades include YG6, YG8, etc.; YT-type cemented carbide, i.e., tungsten-titanium-cobalt cemented carbide, mainly consists of the hardening phase tungsten carbide, titanium carbide and the bonding metal cobalt, and the optional grades include YT14, YT15, etc.; YW-type cemented carbide, i.e., tungsten-titanium-tantalum / niobium cemented carbide, mainly consists of the hardening phase tungsten carbide, titanium carbide, tantalum carbide / niobium carbide and the bonding metal cobalt, and the optional grades include YW1, YW2, etc.

[0026] Cemented carbide has excellent mechanical properties such as high hardness, high wear resistance and high toughness, and is widely used in tool materials or processes such as cutting hard materials; in the present invention, by uniformly mixing a small amount of cemented carbide into the solder paste, different functions are achieved before, during and after welding.

[0027] Before welding, during the process of overlapping the workpieces to be welded and applying the solder paste, the cemented carbide particles with large volume, high gravity and not easy to flow are embedded in the weld seam, playing a supporting role similar to a skeleton, avoiding the loss of the fluid solder paste, and thus ensuring that the components of the filler metal and the flux are not easy to fall off or be extruded. During welding, the welding gap is ensured by the supporting role of the cemented carbide particles with large particle size and relatively high melting point, which is convenient for the discharge of impurities such as welding slag and binder residues. When the workpiece to be welded also contains cemented carbide, the cemented carbide particles in the solder paste achieve metallurgical bonding with the alloy components of the workpiece with similar properties, and the two are tightly bonded through high-temperature reaction, further improving the weld strength. At the same time, after welding, the cemented carbide particles are uniformly dispersed in the weld seam, forming an effective bond with the cemented carbide workpiece to be welded and the filler metal, forming a "pinning" phenomenon, greatly improving the welding strength.

[0028] As a preferred embodiment, the particle size of the cemented carbide includes but is not limited to: 0.03 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm. At the same time, as an optional embodiment, the particle size of the filler metal is 100 mesh to 300 mesh, and the particle size of the flux is less than 100 mesh.

[0029] As a preferred embodiment, the solder includes one of a silver-based solder or a copper-based solder; wherein the silver-based solder includes: Ag 1%-65%, Cu 10%-60%, Zn10%-40%, Ni 0.1%-8%, Mn 0.1%-8%, Co 0.1%-2%, Si 0.01%-1%; the copper-based solder includes: Cu 10%-65%, Zn 20%-60%, Ni 0.5%-25%, Mn 0.5%-25%, Co 0.1%-15%, Si 0.1%-1%, Fe 0.1%-5%, P0.1%-2%.

[0030] As a preferred embodiment, the brazing agent includes at least one of potassium fluoride, calcium fluoride, boric anhydride, boric acid, potassium fluoroborate, potassium borate and dehydrated borax; such as a single component, or a combination of two or three, or a combination of all of the above types, etc. The specific brazing agent selection depends on the type of brazing material, and those skilled in the art can select the most suitable brazing agent type according to the type of brazing material.

[0031] As a preferred embodiment, the particle enhanced solder paste also includes a binder, and the weight percentage of the binder includes but is not limited to the following parameter values, or an interval range formed by the following parameter values: 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30 (parts).

[0032] As a more preferred embodiment, the particle-enhanced solder paste is composed of the following components by mass percentage: 40% to 80% solder, 5% to 25% flux, 0.1% to 5% granular cemented carbide, and 8% to 30% binder.

[0033] Example 1

[0034] (1) Cu 53.5%, Zn 34%, Ni 6%, Mn 4%, Co 1.5%, Si 0.2%, Fe 0.6%, P 0.2% are weighed in the form of single elements or intermediate alloys, and a copper-based alloy powder with a size of less than 200 mesh is obtained by atomizing.

[0035] (2) Select YG8 as the cemented carbide particles and grind them to an average particle size of 0.1 mm to 0.15 mm.

[0036] (3) A 100-mesh mixed powder was prepared by a planetary grinder with 4% potassium fluoride, 13% calcium fluoride, 62% boric anhydride, 2% potassium fluoroborate, and 19% dehydrated borax, and then mechanically mixed for 2 hours.

[0037] (4) Mix the powders and vaseline from steps (1), (2), and (3); among them, the weight parts of the alloy powder, cemented carbide particles, flux mixed powder, and vaseline are 65, 2, 15, and 18 (parts) respectively, stir evenly and prepare a copper-based solder paste.

[0038] Example 2

[0039] (1) Weigh the corresponding weights in the form of elemental elements or master alloys in the proportion of Ag 25%, Cu 37.3%, Zn 33%, Ni 2%, Mn 2%, Co 0.5%, Si 0.2%, and obtain silver-based alloy powder with a particle size less than 200 mesh by gas atomization powder making.

[0040] (2) Select YG8 for the cemented carbide particles and grind them to an average particle size of 0.1 mm to 0.15 mm.

[0041] (3) Prepare a 100-mesh mixed powder with 41% potassium fluoride, 1% calcium fluoride, 35% boric anhydride, and 23% potassium fluoroborate by a planetary mill, and then mechanically mix for 2 hours.

[0042] (4) Mix the powders and vaseline from steps (1), (2), and (3); among them, the weight parts of the alloy powder, cemented carbide particles, flux mixed powder, and vaseline are 65, 2, 15, and 18 (parts) respectively, stir evenly and prepare a silver-based solder paste.

[0043] Example 3

[0044] Basically the same as Example 1, the only difference is:

[0045] In step (4), the weight parts of the alloy powder, cemented carbide particles, flux mixed powder, and vaseline are 40, 0.1, 5, and 8 (parts) respectively.

[0046] Example 4

[0047] Basically the same as Example 1, the only difference is:

[0048] In step (4), the weight parts of the alloy powder, cemented carbide particles, flux mixed powder, and vaseline are 80, 5, 25, and 30 (parts) respectively.

[0049] Example 5

[0050] Basically the same as Example 2, the only difference is:

[0051] In step (4), the weight parts of the alloy powder, cemented carbide particles, flux mixed powder, and vaseline are 40, 0.1, 5, and 8 (parts) respectively.

[0052] Example 6

[0053] It is basically the same as Example 2, with the only difference being that:

[0054] In step (4), the weight parts of the alloy powder, cemented carbide particles, flux mixed powder, and vaseline are 80, 5, 25, and 30 (parts) respectively.

[0055] Comparative Example 1

[0056] It is basically the same as Example 1, with the only difference being that:

[0057] Step (2) is not carried out, and cemented carbide particles are not added in step (4) either. The weight parts of the alloy powder, flux mixed powder, and vaseline are 65, 15, and 18 (parts) respectively.

[0058] Comparative Example 2

[0059] It is basically the same as Example 2, with the only difference being that:

[0060] Step (2) is not carried out, and cemented carbide particles are not added in step (4) either. The weight parts of the alloy powder, flux mixed powder, and vaseline are 65, 15, and 18 (parts) respectively.

[0061] Test Example

[0062] To investigate the welding strength of the particle-reinforced solder paste and the traditional solder paste in the present invention, the following experiments are carried out: The brazing experiments are respectively carried out on Examples 1-6 and Comparative Examples 1-2 of the present invention. The brazing base materials are steel 40Cr and cemented carbide YG8, and lap welding is carried out. The brazing process flow is as follows: (1) The welding surface of the base material is polished with sandpaper, cleaned with alcohol, and then dried at 100 °C for standby. (2) The inventive solder paste is filled into a syringe and quantitatively added to the weld seam by means of dispensing. (3) The workpieces to be welded are fixed with a fixture and placed in an induction welding coil. (4) The high-frequency welding machine is turned on to melt the solder paste and make the excess solder precipitate from the weld seam to ensure that the weld seam is fully welded. (5) After welding, the workpiece is placed in a furnace at 400 °C for 2 hours for heat preservation. (6) It is cooled to room temperature in the furnace, and the excess solder around the weld seam is ground off. (7) A universal testing machine is used for mechanical property testing, and the test results are shown in Table 1.

[0063] Table 1 Test results of brazed joint strength

[0064] Solder paste type Average shear strength of joints / KN Solder paste usage / g Example 1 303 0.35 Example 2 201 0.35 Example 3 293 0.35 Example 4 298 0.35 Example 5 202 0.35 Example 6 209 0.35 Comparative example 1 274 0.35 Comparative example 2 186 0.35

[0065] Although the present invention has been illustrated and described with reference to specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A particle-reinforced solder paste, characterized in that, The particulate-reinforced solder paste comprises, by mass parts: 40 to 80 parts of filler metal, 5 to 25 parts of flux, 0.1 to 5 parts of particulate cemented carbide, and 8 to 30 parts of binder; wherein, the cemented carbide comprises tungsten carbide; The filler metal comprises at least one of silver-based filler metal, copper-based filler metal, nickel-based filler metal, cobalt-based filler metal, and palladium-based filler metal; the copper-based filler metal comprises the following elements: Cu, Zn, Ni, Mn, Co, Si, Fe, and P; The particle size of the cemented carbide is 0.1 mm to 0.5 mm.

2. The particulate-reinforced solder paste according to claim 1, wherein The cemented carbide further comprises at least one of titanium carbide, tantalum carbide, and niobium carbide.

3. The particulate-reinforced solder paste according to claim 1, wherein, The cemented carbide comprises at least one of tungsten-cobalt cemented carbide, tungsten-titanium-cobalt cemented carbide, tungsten-titanium-tantalum cemented carbide, and tungsten-titanium-niobium cemented carbide.

4. The particulate-reinforced solder paste according to claim 1, wherein The filler metal comprises one of silver-based filler metal or copper-based filler metal.

5. The particulate-reinforced solder paste according to claim 1, wherein The silver-based filler metal comprises the following elements: Ag, Cu, Zn, Ni, Mn, Co, and Si.

6. The particulate-reinforced solder paste according to claim 5, wherein The silver-based filler metal comprises: 10% to 60% of Cu, 10% to 40% of Zn, 0.1% to 8% of Ni, 0.1% to 8% of Mn, 0.1% to 2% of Co, 0.01% to 1% of Si, with the balance being Ag.

7. The particulate-reinforced solder paste according to claim 1, wherein, The copper-based filler metal comprises: 20% to 60% of Zn, 0.5% to 25% of Ni, 0.5% to 25% of Mn, 0.1% to 15% of Co, 0.1% to 1% of Si, 0.1% to 5% of Fe, 0.1% to 2% of P, with the balance being Cu.

8. The particulate-reinforced solder paste according to claim 1, wherein The flux comprises at least one of potassium fluoride, calcium fluoride, boric anhydride, boric acid, potassium fluoroborate, potassium borate, and dehydrated borax.

9. The particulate-reinforced solder paste according to claim 1, wherein, The binder comprises at least one of petrolatum, polyisobutylene, and polycarbonate propylene ester.

10. The preparation method of the particle-reinforced solder paste according to any one of claims 1 to 9, characterized in that, It includes the following steps: Fully mix each component to obtain the solder paste; Before performing the mixing, it further includes: pretreating the filler metal and the flux until the filler metal and the flux are in powder form.

11. Use of the particulate-reinforced solder paste according to any one of claims 1 to 9 in brazing.

12. The use according to claim 11, wherein, The particulate-reinforced solder paste is used for welding workpieces containing cemented carbide.