Yb and Tb co-doped alloy brazing filler metal, preparation method and brazing process

Abstract

The invention relates to the technical field of brazing, and discloses Yb and Tb co-doped alloy brazing filler metal, a preparation method and a brazing process. The Yb and Tb co-doped alloy brazing filler metal comprises, by mass, 12%-13% of chromium, 3%-4% of boron, 3%-4% of silicon, 4%-5% of iron, 0.5%-2% of terbium, 0.5%-1.5% of ytterbium and the balance nickel. Yb and Tb co-doping effectively inhibits growth of dendrites, rare earth elements are easily enriched at the grain boundary to form a fine isometric crystal structure, the prepared Yb and Tb co-doped alloy brazing filler metal brazed diamond is smaller in thermal damage degree, the brazed surface is smooth and free of accumulation, and the phenomena of wrinkles and holes are reduced to a great extent. The rare earth co-doping is beneficial to improving the wettability of the brazing filler metal, the brazing filler metal and the diamond are subjected to violent chemical metallurgy, the interface bonding strength of the brazing filler metal and the diamond is improved, and therefore the machining performance of a diamond tool is improved.

Description

Technical Field

[0001] The invention relates to the technical field of brazing, and in particular to a Yb and Tb co-doped alloy brazing material, a preparation method and a brazing process. Background Art

[0002] Diamond, due to its ultra-high hardness, excellent wear resistance, and thermal conductivity, is widely used in cutting, grinding, and mining drilling. However, effectively improving the overall performance of brazed diamond tools, particularly enhancing the bond between diamond and brazing filler metal to inhibit thermal damage, remains a research hotspot and a challenge. Rare earth elements (REs) are widely used in metal-matrix composites due to their unique physicochemical properties (such as high surface activity, strong reducing properties, and extremely low solubility). REs not only significantly enhance the wettability of the brazing filler metal but also improve the microstructure and mechanical properties of brazed diamond joints through interfacial reactions.

[0003] Currently, there is a lack of research on the doping effects and modification mechanisms of heavy rare earth elements in the field of diamond brazing. In particular, the interfacial reaction process between the brazing material and diamond after heavy rare earth element doping has not been fully discussed and elucidated. Rare earth doping alone has improved the microstructure of Ni-Cr brazing material to a certain extent, effectively refined the grain size, and alleviated thermal damage to diamond to a certain extent. However, research on single rare earth doping is relatively comprehensive, while research on co-doping with two rare earth elements remains unresolved. Co-doping with two rare earth elements will be a focus of further research. In order to address the technical difficulties of brazing diamond with Ni-Cr brazing material, it is urgent to design a high-performance rare earth-doped Ni-Cr brazing material for diamond brazing. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a Yb and Tb co-doped alloy solder, a preparation method and a brazing process. Yb and Tb co-doping effectively inhibits the growth of dendrites, and rare earth elements are easily enriched at grain boundaries, which can serve as heterogeneous nucleation points to hinder the growth of other phases, thereby forming a fine equiaxed crystal structure. The Yb and Tb co-doped alloy solder brazing diamond has a lower degree of thermal damage, the brazing surface is relatively smooth without accumulation, and the phenomenon of wrinkles and holes is greatly reduced. Rare earth co-doping is conducive to improving the wettability of the solder, and the solder and diamond undergo intense chemical metallurgy, which improves the interface bonding strength between the solder and diamond, thereby improving the processing performance of diamond tools.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a Yb and Tb co-doped alloy solder comprises the following steps: Step (1): grinding nickel, chromium, boron, silicon, iron, terbium, and ytterbium, ultrasonically treating them, taking them out, and drying them to obtain a pre-dried alloy raw material; Step (2): placing the pre-dried alloy raw material in a crucible of a smelting furnace, smelting the alloy, cooling it with the furnace after smelting, and taking it out to obtain a brazing ingot; Step (3): cutting the solder ingot to obtain a flake alloy solder, polishing, and drying to obtain a Yb and Tb co-doped alloy solder.

[0006] Preferably, in step (1), the ultrasonic treatment operation comprises: in an ultrasonic cleaning machine, ultrasonically oscillating and cleaning in acetone for 10-15 minutes, and then transferring to ethanol and continuing ultrasonic treatment for 5-10 minutes.

[0007] Preferably, in step (2), the order of adding the pre-dried alloy raw materials is as follows: placing them in the copper crucible of the smelting furnace according to the gradient distribution of the element melting points.

[0008] Furthermore, in the step (2), the order of adding the pre-dried alloy raw materials is as follows: ytterbium, terbium, silicon, nickel, iron, chromium, and boron are placed in the copper crucible of the smelting furnace in the order of ytterbium, terbium, silicon, nickel, iron, chromium, and boron.

[0009] Preferably, in step (2), the conditions for melting the alloy are: using a mechanical pump to draw a low vacuum to 1×10 -1 Pa, and then use a molecular pump to draw a high vacuum to 3×10 -3 Pa, turn off the molecular pump, and melt the alloy in an Ar atmosphere at a pressure of -0.05 MPa.

[0010] Preferably, in step (2), the smelting operation is as follows: turning on the smelting power supply heating switch to make the voltage between 60-80 V, then performing high-frequency arc ignition to control the heating current in the smelting furnace to be 250-280 A, and repeatedly turning the alloy ingot over and remelting it 3-4 times to make its composition uniform.

[0011] Preferably, in step (3), the specifications of the sheet alloy solder are: length 12-15 mm, thickness 150-180 μm.

[0012] Preferably, in step (3), the mass percentage of each component in the Yb and Tb co-doped alloy solder is: 12-13% chromium, 3-4% boron, 3-4% silicon, 4-5% iron, 0.5-2% terbium, 0.5-1.5% ytterbium, and the balance is nickel.

[0013] Preferably, a Yb and Tb co-doped alloy solder is prepared by the method for preparing the Yb and Tb co-doped alloy solder as described above.

[0014] A brazing process for a Yb and Tb co-doped alloy solder, the brazing process comprising the following steps: Take a No. 45 steel block, apply an adhesive on the brazing surface of the steel block, spread the Yb and Tb co-doped alloy brazing material prepared above on the brazing surface coated with the adhesive, and then arrange diamond abrasives in an orderly manner on the upper surface of the flaky alloy brazing material. Place the steel block, flaky alloy brazing material and diamond abrasives in sequence from bottom to top, dry, braze connection, keep warm, cool, cool with the furnace, and take out to obtain Yb and Tb co-doped alloy brazing material brazing diamond.

[0015] Preferably, the size of the No. 45 steel block is 15 mm×10 mm×6 mm, and the coating amount of the adhesive is 3-8 mg.

[0016] Preferably, the heat preservation condition is: at a vacuum degree of 4×10 -4 Pa, heat to 1080°C at a heating rate of 10°C / min and keep warm for 5-8 minutes.

[0017] Preferably, the cooling condition is: cooling to 500° C. at a cooling rate of 5° C. / min.

[0018] Preferably, a Yb and Tb co-doped alloy brazing material is used to braze diamond using the Yb and Tb co-doped alloy brazing material prepared by the brazing process of the Yb and Tb co-doped alloy brazing material as described above.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The Ni-Cr-B-Si-Fe brazing filler metal used in this invention is the most popular brazing filler metal for diamond brazing, offering advantages such as low cost, excellent wear resistance, and high bonding strength, making it the preferred choice for brazing diamond tools. The choice of base material for brazing diamond tools determines the wear resistance and thermal conductivity of the diamond tool during machining, a significant factor influencing machining performance. The 45 steel used in this invention exhibits excellent welding properties and thermal conductivity. 45 steel also exhibits a certain degree of corrosion resistance, effectively preventing oxidation and corrosion. Furthermore, 45 steel is a common medium-carbon steel with a relatively low price, making it suitable for large-scale production and application.

[0020] The vacuum arc melting method adopted in the present invention can effectively avoid impurity contamination such as oxidation and inclusion when preparing solder, and significantly improve the purity of the alloy; it is conducive to the full mixing of various components, ensuring the uniformity of composition to provide a good foundation for subsequent processing, and the quality of the solder can be further improved through multiple smelting; when preparing solder by vacuum arc melting, the raw materials are placed in the copper crucible in the order of the melting points of the elements from low to high, which is to ensure that the high-melting-point elements can be fully melted first in the initial stage. At the same time, the low-melting-point elements are placed in the lower layer to effectively prevent their possible volatilization loss at high temperatures, which helps to accurately control the composition; in addition, this layered loading method causes the high-melting-point elements to melt first near the arc, and then the low-melting-point elements are melted through heat transfer. Compared with randomly placing them together, it can promote the full mixing of elements during the smelting process, improve the uniformity of the alloy during the smelting process, thereby ensuring the stability of the smelting process and the final alloy quality.

[0021] 2. In the present invention, Yb effectively improves brazing filler metal wettability and enhances the chemical metallurgical bonding between the filler metal and diamond, while Tb increases the filler metal hardness while promoting the uniformity and stability of the interfacial reaction. Furthermore, rare earth co-doping forms a denser, more continuous reaction layer at the brazed joint interface, enhancing the joint's bond strength and significantly improving the joint's thermal stability and mechanical properties. Therefore, through the synergistic effect of Yb and Tb co-doping, the present invention offers significant advantages in improving brazing quality, extending product life, and expanding its application range.

[0022] 3. Co-doping of rare earth elements Yb and Tb can effectively refine grains and inhibit dendrite growth. Four rare earth phases, NiTb, Tb3Ni, Ni7Yb2, and NiYb3, are generated in the solder after co-doping. Variations in the co-doping content do not result in changes in the rare earth phases.

[0023] 4. Co-doping with rare earth Yb and Tb improves the brazing material's fluidity, significantly reducing wrinkles and holes. Furthermore, the diamond crystal structure remains relatively intact after brazing. The combined effects of Yb and Tb reduce the chemical corrosion of the diamond caused by the catalytic element Ni.

[0024] 5. Rare earth co-doping improves the wettability of Ni-Cr brazing filler metal, allowing the filler metal to climb the sides of the diamond abrasive grains to a high degree. Diamond brazing with Yb and Tb co-doped alloy fillers exhibits superior mechanical properties.

[0025] 6. Rare earth co-doping forms denser carbides, which alleviate stress concentration and crack formation to a certain extent, thereby significantly improving the thermal stability and mechanical properties of the joint, and improving the wear resistance and processing performance of the diamond sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is a microstructure diagram of the Yb and Tb co-doped alloy solder prepared in Example 1-6; Figure 2 is a microstructure diagram of the Ni-Cr solder prepared in Comparative Examples 1-3; Figure 3 1 is a microstructure surface scan of the Ni-Cr CFA2 solder prepared in Example 2; Figure 4 is the XRD pattern of the Yb and Tb co-doped alloy solder prepared in Example 1-6; Figure 5 is a histogram of the microhardness of the Yb and Tb co-doped alloy solders prepared in Examples 1-6; Figure 6 is a morphology picture of diamond brazed with Yb and Tb co-doped alloy brazing filler metal prepared in Example 7; Figure 7 This is a morphology image of diamond brazed with Ni-Cr solder prepared in Comparative Example 4; Figure 8 This is an EDS scan of the diamond surface brazed with Ni-Cr CFA2 brazing filler metal prepared in Example 7; Figure 9 This is a diagram showing the diamond exposure during brazing using the Yb and Tb co-doped alloy brazing material prepared in Example 7; Figure 10 This is a morphology of carbide on the surface of diamond brazed with the Yb and Tb co-doped alloy brazing filler metal prepared in Example 7; Figure 11 This is a morphology of carbide on the surface of diamond brazed with Ni-Cr brazing filler metal prepared in Comparative Example 4; Figure 12 This is a Raman spectrum of diamond brazed with Yb and Tb co-doped alloy solder prepared in Example 7; Figure 13 This is a Raman test result of diamond brazing with Ni-Cr solder prepared in Comparative Example 4; Figure 14 is a bar graph of the static pressure strength of diamond brazed with the Yb and Tb co-doped alloy brazing filler metal prepared in Example 7; Figure 15 This is a wear morphology of diamond brazed with Yb and Tb co-doped alloy brazing filler metal prepared in Example 7; Figure 16 The friction coefficient curve and the alumina ceramic removal amount histogram of the Yb and Tb co-doped alloy brazing material prepared in Example 7 are shown; Figure 17 This is an EDS surface scan of the interface between the brazing filler metal and the diamond in the brazing of diamond using the Ni-Cr CFA1 brazing filler metal prepared in Example 7; Figure 18This is an EDS line scan image of the interface between the brazing filler metal and the diamond in the brazing of diamond using the Ni-Cr CFA1 brazing filler metal prepared in Example 7; Figure 19 This is an EDS surface scan of the interface between the brazing filler metal and the diamond in the brazing of diamond using the Ni-Cr CFA2 brazing filler metal prepared in Example 7; Figure 20 This is an EDS line scan image of the interface between the brazing filler metal and the diamond in the brazing of diamond using Ni-Cr CFA2 brazing filler metal prepared in Example 7; Figure 21 This is an EDS surface scan of the interface between the brazing filler metal and the diamond in the brazing of diamond using the Ni-Cr CFA3 brazing filler metal prepared in Example 7; Figure 22 This is an EDS line scan image of the interface between the brazing filler metal and the diamond in the brazing of diamond using the Ni-Cr CFA3 brazing filler metal prepared in Example 7; Figure 23 This is an EDS surface scan of the interface between the brazing filler metal and the diamond in the brazing of diamond using the Ni-Cr CFA4 brazing filler metal prepared in Example 7; Figure 24 This is an EDS line scan image of the interface between the brazing filler metal and the diamond in the brazing of diamond using the Ni-Cr CFA4 brazing filler metal prepared in Example 7; Figure 25 This is an EDS surface scan of the interface between the brazing filler metal and the diamond in the brazing of diamond with the Ni-Cr CFA5 brazing filler metal prepared in Example 7; Figure 26 This is an EDS line scan image of the interface between the brazing filler metal and the diamond in the brazing of diamond with the Ni-Cr CFA5 brazing filler metal prepared in Example 7; Figure 27 This is an EDS surface scan of the interface between the brazing filler metal and the diamond in the brazing of diamond using Ni-Cr CFA6 brazing filler metal prepared in Example 7; Figure 28 This is an EDS line scan image of the interface between the brazing filler metal and the diamond in the brazing of diamond using Ni-Cr CFA6 brazing filler metal prepared in Example 7; In the picture: Figure 1(a) is the Ni-Cr CFA1 prepared in Example 1, the left picture is the SEM picture at the scale of 10 μm, and the right picture is the SEM picture at the scale of 3 μm; (b) is the Ni-Cr CFA2 prepared in Example 2, the left picture is the SEM picture at the scale of 10 μm, and the right picture is the SEM picture at the scale of 3 μm; (c) is the Ni-Cr CFA3 prepared in Example 3, the left picture is the SEM picture at the scale of 10 μm, and the right picture is the SEM picture at the scale of 3 μm; (d) is the Ni-Cr CFA4 prepared in Example 4, the left picture is the SEM picture at the scale of 10 μm, and the right picture is the SEM picture at the scale of 3 μm; (e) is the Ni-Cr CFA5 prepared in Example 5, the left picture is the SEM picture at the scale of 10 μm, and the right picture is the SEM picture at the scale of 3 μm; (f) is the Ni-Cr prepared in Example 6 CFA6, the left image is a SEM image with a 10 μm scale, and the right image is a SEM image with a 3 μm scale; Figure 2 (a) is Ni-Cr 1 prepared in Comparative Example 1; (b) is Ni-Cr 2 prepared in Comparative Example 2; (c) is Ni-Cr 3 prepared in Comparative Example 3; Figure 3 A, B, and C in the figure are the points of EDS point scanning; Figure 6 (a) is the Ni-Cr CFA1 brazing filler metal brazed diamond prepared in Example 7, the left picture is the SEM picture at 100 μm scale, and the right picture is the SEM picture at 30 μm scale; (b) is the Ni-Cr CFA2 brazing filler metal brazed diamond prepared in Example 7, the left picture is the SEM picture at 100 μm scale, and the right picture is the SEM picture at 30 μm scale; (c) is the Ni-Cr CFA3 brazing filler metal brazed diamond prepared in Example 7, the left picture is the SEM picture at 100 μm scale, and the right picture is the SEM picture at 30 μm scale; (d) is the Ni-Cr CFA4 brazing filler metal brazed diamond prepared in Example 7, the left picture is the SEM picture at 100 μm scale, and the right picture is the SEM picture at 30 μm scale; (e) is the Ni-Cr Diamond brazed with CFA5 filler metal, the left image is a SEM image at a 100 μm scale, and the right image is a SEM image at a 30 μm scale; (f) Diamond brazed with Ni-Cr CFA6 filler metal, prepared in Example 7, the left image is a SEM image at a 100 μm scale, and the right image is a SEM image at a 30 μm scale; Figure 7 (a) is the Ni-Cr 1 brazed diamond prepared in Comparative Example 1; (b) is the Ni-Cr 2 brazed diamond prepared in Comparative Example 2; (c) is the Ni-Cr 3 brazed diamond prepared in Comparative Example 3; Figure 11(a) is the Ni-Cr 1 brazing filler metal brazed diamond prepared in Comparative Example 4; (b) is the Ni-Cr 2 brazing filler metal brazed diamond prepared in Comparative Example 4; (c) is the Ni-Cr 3 brazing filler metal brazed diamond prepared in Comparative Example 4; Figure 9 、 Figure 10 、 Figure 15 (a) is the diamond brazed with Ni-Cr CFA1 solder prepared in Example 7; (b) is the diamond brazed with Ni-Cr CFA2 solder prepared in Example 7; (c) is the diamond brazed with Ni-Cr CFA3 solder prepared in Example 7; (d) is the diamond brazed with Ni-Cr CFA4 solder prepared in Example 7; (e) is the diamond brazed with Ni-Cr CFA5 solder prepared in Example 7; (f) is the diamond brazed with Ni-Cr CFA6 solder prepared in Example 7. Figure 16 (a) is the friction coefficient curve, and (b) is the histogram of the alumina ceramic removal amount. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment discloses a method for preparing a Yb and Tb co-doped alloy solder, comprising the following steps: Step (1): Use sandpaper to polish nickel, chromium, boron, silicon, iron, terbium, and ytterbium to remove surface oxide films and impurities, place them in an ultrasonic cleaning machine, ultrasonically clean them in acetone for 10 minutes, transfer them to ethanol and continue ultrasonic treatment for 5 minutes, take them out, and dry them to obtain a pre-dried alloy raw material; Step (2): Place the pre-dried alloy raw materials in the order of ytterbium, terbium, silicon, nickel, iron, chromium, and boron into the copper crucible of the smelting furnace, and first use a mechanical pump to draw a low vacuum to 1×10 -1 Pa, and then use a molecular pump to draw a high vacuum to 3×10 -3 Pa, turn off the molecular pump, and melt the alloy in an Ar gas atmosphere at a pressure of -0.05 MPa. After the melting is completed, cool it with the furnace and take it out to obtain a brazing ingot; The smelting operation is as follows: turn on the smelting power heating switch to make the voltage between 60-80 V, then perform high-frequency arc ignition to control the heating current in the smelting furnace to 260 A, and repeatedly turn the alloy ingot over and remelt it three times to make its composition uniform; Step (3): The brazing ingot was cut with a diamond wire cutting machine to obtain a sheet alloy brazing material with a length of 15 mm and a thickness of 150 μm. The surface of the sheet brazing material was polished smooth with a metallographic polishing machine and dried at 50°C to obtain a Yb and Tb co-doped alloy brazing material, which was recorded as Ni-Cr CFA1. Among them, in the Yb and Tb co-doped alloy solder, the mass percentage of each component is: 76% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), 1.5% terbium (Tb), and 0.5% ytterbium (Yb).

[0030] Example 2

[0031] The difference from Example 1 is that the mass percentage of each component in the Yb and Tb co-doped alloy solder is changed to: 75.5% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), 1.5% terbium (Tb), and 1% ytterbium (Yb), denoted as Ni-Cr CFA2; other parameters and conditions are the same as in Example 1.

[0032] Example 3

[0033] The difference from Example 1 is that the mass percentage of each component in the Yb and Tb co-doped alloy solder is changed to: 75% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), 1.5% terbium (Tb), and 1.5% ytterbium (Yb), denoted as Ni-Cr CFA3; other parameters and conditions are the same as in Example 1.

[0034] Example 4

[0035] The difference from Example 1 is that the mass percentage of each component in the Yb and Tb co-doped alloy solder is changed to: 76.5% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), 0.5% terbium (Tb), and 1% ytterbium (Yb), denoted as Ni-Cr CFA4; other parameters and conditions are the same as in Example 1.

[0036] Example 5

[0037] The difference from Example 1 is that the mass percentage of each component in the Yb and Tb co-doped alloy solder is changed to: 76% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), 1% terbium (Tb), and 1% ytterbium (Yb), denoted as Ni-Cr CFA5; other parameters and conditions are the same as in Example 1.

[0038] Example 6

[0039] The difference from Example 1 is that the mass percentage of each component in the Yb and Tb co-doped alloy solder is changed to: 75% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), 2% terbium (Tb), and 1% ytterbium (Yb), denoted as Ni-Cr CFA6; other parameters and conditions are the same as in Example 1.

[0040] Example 7

[0041] This embodiment discloses a brazing process for a Yb and Tb co-doped alloy solder, comprising the following steps: A No. 45 steel block with a size of 15 mm × 10 mm × 6 mm was taken, and 5 mg of adhesive was applied to the brazing surface of the steel block. The Yb and Tb co-doped alloy brazing materials prepared in Examples 1-6 were respectively spread flat on the brazing surface coated with the adhesive. Diamond abrasives were then arranged in order on the upper surface of the flaky alloy brazing material. The steel block, flaky alloy brazing material, and diamond abrasives were placed in order from bottom to top, and dried at 50 ° C. After drying, they were placed in a high vacuum molybdenum strip brazing furnace for brazing connection. The vacuum degree was 4×10 -4 Pa, the temperature was increased to 1080℃ at a heating rate of 10℃ / min and kept for 5 min, then cooled to 500℃ at a cooling rate of 5℃ / min, cooled to room temperature with the furnace, and taken out to obtain Yb and Tb co-doped alloy brazing diamond, which were respectively recorded as Ni-Cr CFA1 brazing filler metal brazing diamond, Ni-Cr CFA2 brazing filler metal brazing diamond, Ni-Cr CFA3 brazing filler metal brazing diamond, Ni-Cr CFA4 brazing filler metal brazing diamond, Ni-Cr CFA5 brazing filler metal brazing diamond, and Ni-Cr CFA6 brazing filler metal brazing diamond.

[0042] Comparative Example 1 The difference from Example 1 is that in the Ni-Cr solder, the mass percentage of each component is changed to: 78% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), and 4% iron (Fe), denoted as Ni-Cr1; other parameters and conditions are the same as in Example 1.

[0043] Comparative Example 2 The difference from Example 1 is that in the Ni-Cr solder, the mass percentage of each component is changed to: 77% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), and 1% ytterbium (Yb), denoted as Ni-Cr2; other parameters and conditions are the same as in Example 1.

[0044] Comparative Example 3 The difference from Example 1 is that in the Ni-Cr solder, the mass percentage of each component is changed to: 76.5% nickel (Ni), 12% chromium (Cr), 3% boron (B), 3% silicon (Si), 4% iron (Fe), and 1.5% terbium (Tb), denoted as Ni-Cr3; other parameters and conditions are the same as in Example 1.

[0045] Comparative Example 4 The difference from Example 7 is that the Ni-Cr brazing filler metal used is the brazing filler metal prepared in Comparative Examples 1-3; the other parameters and conditions are the same as those in Example 7, and the obtained Ni-Cr brazing filler metal brazed diamonds are respectively recorded as Ni-Cr1 brazing filler metal brazed diamond, Ni-Cr2 brazing filler metal brazed diamond, and Ni-Cr3 brazing filler metal brazed diamond.

[0046] In the above embodiments and comparative examples: the raw materials of nickel (99.9%), chromium (99.9%), boron (99.9%), silicon (99.9%), iron (99.9%), terbium (99.9%), and ytterbium (99.9%) are provided by Chengshuo Metal Materials Co., Ltd. in granular form; the binder is provided by Yantai Guguang Company and the specification is ZT-W02 type.

[0047] Experimental data characterization and performance testing like Figure 1 As shown, the solders prepared in Examples 1-6 and Comparative Examples 1-3 were tested by scanning electron microscopy. according to Figure 1 The test results show that the microstructure of the Ni-Cr CFA1 solder prepared in Example 1 is mainly composed of cellular crystals, with equiaxed crystals formed in local areas; the Ni-Cr CFA2 solder prepared in Example 2 is co-doped with the optimal doping amount of Yb and the optimal doping amount of Tb, and its structure is mainly composed of fine equiaxed crystals; as the doping amount of Yb increases, the Ni-Cr CFA3 solder prepared in Example 3 begins to form secondary dendrites, and the grain size is larger. This is mainly due to the large total doping amount of rare earth, which reduces the supercooling of the solder and slows down the cooling rate, resulting in weakened grain refinement and increased grain size, which is conducive to the formation of dendrites. Figure 2From the test results, it can be seen that the microstructure of the Ni-Cr 1 solder prepared in Comparative Example 1 is mainly composed of coarse dendrites and secondary dendrites with large spacing; the microstructure of the Ni-Cr 2 solder prepared in Comparative Example 2 is refined, but shows an obvious dendritic structure, with dendrite dissolution occurring in some parts of the dendrites and a cellular crystal structure appearing locally; the microstructure of the Ni-Cr 3 solder prepared in Comparative Example 3 has a slightly reduced size of dendrites, but is still dominated by an obvious dendritic structure.

[0048] In summary, when the optimal Yb doping level is fixed and the Tb doping level is varied, the solder microstructure shows no equiaxed grains and is dominated by cellular and columnar grains, achieving superior microstructure refinement compared to conventional Ni-Cr solders without rare earth doping. The solder microstructure demonstrates that the most significant grain refinement occurs when the optimal Yb doping level is co-doped with the optimal Tb doping level.

[0049] Since the Ni-Cr CFA2 solder prepared in Example 2 has an obvious microstructure refinement effect, an EDS surface scan is performed on the Ni-CrCFA2 solder prepared in Example 2. Figure 3 As shown; according to Figure 3 The test results show that rare earth Yb and Tb tend to be enriched at the grain boundaries, hindering the growth of other phases, thereby achieving the purpose of grain refinement. Studies have shown that the rare earth phase formed is small and can serve as a heterogeneous nucleation point, prompting the grains to nucleate and grow at the nucleation point, increasing the nucleation rate and playing the role of a nucleating agent. However, the rare earth content should not be too high, which is also related to Figure 3 is consistent with the research results.

[0050] In order to explore the possible phases generated in the solder, as shown in Table 1, EDS point scanning was performed on the Ni-enriched area, Cr-enriched area, and rare earth element-enriched area in the Ni-Cr CFA2 solder prepared in Example 2; Table 1

[0051] According to the test results in Table 1, it can be seen that rare earth compounds are generated at the grain boundaries, which indicates that rare earth elements are easily enriched at the grain boundaries, effectively inhibiting the growth of grains, and thus obtaining a refined solder structure.

[0052] like Figure 4 As shown, XRD tests were performed on the solders prepared in Examples 1-6 respectively; according to Figure 4The test results show that the Yb and Tb co-doped alloy solders prepared in Examples 1-6 primarily form phases such as γ-Ni, Ni3Fe, CrB, and Ni3Si2, as well as rare earth phases such as NiYb3, Ni7Yb2, Tb3Ni, and NiTb, confirming the results in Table 1. Furthermore, the rare earth phases generated by co-doping Yb and Tb with Ni are identical to those generated by single doping, indicating that co-doping does not affect the formation of rare earth phases in the solder.

[0053] like Figure 5 As shown, microhardness tests were performed on the solders prepared in Examples 1-6 and Comparative Example 1; according to Figure 5 The test results show that the Ni-Cr solders prepared in Examples 1-6 after rare earth co-doping have higher microhardness than the Ni-Cr solder prepared in Comparative Example 1 without rare earth doping. The microhardness of the Ni-Cr CFA1 prepared in Example 1 and the Ni-Cr CFA2 prepared in Example 2 are relatively high. This is because the optimal Tb doping amount of 1.5wt.% is fixed and the total rare earth content is relatively low. The microhardness of the Ni-Cr CFA2 solder prepared in Example 2 reaches a maximum of 717.64 HV 0.2 Compared with the Ni-Cr1 solder of comparative example 1 which is not doped with rare earth, the microhardness is 597.73 HV 0.2 It has increased by about 20%. This is because rare earth elements and Ni elements form fine intermetallic compounds, which belong to the second phase strengthening and increase the microhardness of the solder.

[0054] like Figure 6 、 Figure 7 As shown, microscopic morphology tests were performed on the brazing diamonds prepared in Example 7 and Comparative Example 4 respectively; Diamond will be damaged by heat during brazing. The thermal damage mainly includes corrosion pits on the diamond surface, graphitization of diamond and residual stress in the brazed joint. Good diamond morphology is crucial to the mechanical properties of diamond samples. Figure 6 The test results show that after brazing diamond with Yb and Tb co-doped alloy brazing filler metal, the crystal form of the diamond is relatively complete, and no obvious large-scale corrosion pits appear. This shows that during the brazing process, the two rare earth elements work together to chemically react with the Ni element to form a rare earth phase, which reduces the catalytic effect of the Ni element in the brazing filler metal on the diamond. It effectively slows down the weakening of the binding force of the carbon atoms on the diamond surface by the Ni element, preventing the C atoms from dissolving into the brazing filler metal, thereby forming corrosion pits. Figure 7The test results show that larger corrosion pits appear on the surface of diamond brazed with Ni-Cr1 brazing filler metal, the diamond is severely eroded by heat, and the diamond exposure is low; the crystal form of diamond brazed with Ni-Cr2 brazing filler metal is relatively complete, but defects such as obvious cracks and holes appear on the brazing side; larger corrosion pits and corrosion marks appear on the surface of diamond brazed with Ni-Cr3 brazing filler metal, the diamond exposure is low, and the brazing surface is rough, resulting in poor brazing effect.

[0055] In summary, the brazing effect of rare earth co-doping is better than that of undoped and single-doped brazing. The combined effect of the two rare earth elements effectively slows down the weakening of the binding force of carbon atoms on the diamond surface by Ni elements, prevents C atoms from dissolving into the brazing material, reduces the formation of corrosion pits, and thus enables the diamond to maintain its complete crystal form. More cutting edges are more conducive to the grinding effect of diamond abrasives.

[0056] like Figure 8 As shown, EDS surface scanning was performed on the Ni-Cr CFA2 brazing filler metal brazed diamond prepared in Example 7; according to Figure 8 The test results show that the solder spreads freely on the substrate surface, and there is no obvious enrichment of Ni, Cr, Si, Fe, Yb and Tb elements. The elements are close to uniformly distributed, indicating that there is no obvious large-area accumulation of the solder. After rare earth co-doping, the solder has good fluidity, the brazing surface is relatively smooth, and there are no wrinkles, holes or defects.

[0057] like Figure 9 As shown, the exposed height of diamond abrasive grains in the brazing diamond prepared in Example 7 was tested using an ultra-depth-of-field microscope; according to Figure 9 The test results show that the brazing filler metal climbs on the side of the diamond abrasive grains, and the height of the brazing filler metal climbing is relatively high, indicating that the wettability of the Ni-Cr brazing filler metal after rare earth co-doping is better. Figure 9 As shown in (e), it is clearly observed that the brazing material climbs significantly on the side of the diamond, and the exposure of the diamond is relatively low. Figure 9 In (b), the diamond exposure of the Ni-Cr CFA2 brazing filler metal is the highest, which is about 40% of the diamond height.

[0058] like Figure 17-28 As shown, EDS surface scanning and EDS line scanning were performed on the interface between the brazing filler metal and the diamond in the brazing filler metal brazing diamond prepared in Example 7; according to Figure 17-28The test results show that Cr and Si elements appear as distinct, bright bands of enrichment at the interface between diamond and brazing alloy, corresponding to the enrichment of C. Preliminary inference suggests that a carbide layer may form at this location at the interface. Ni elements surrounding the diamond erode the diamond abrasive, allowing more C elements to diffuse from the diamond into the brazing alloy. Cr has a strong affinity with C, attracting Cr elements from the brazing alloy to diffuse toward the diamond and accumulate around it, forming a Cr-enriched zone. The width of the bands in these enriched zones varies, indicating that the thickness of the carbide layer may vary. A small amount of nickel accumulates at the diamond surface, likely related to the wettability of the brazing alloy. Secondly, a line scan perpendicular to the brazing alloy-diamond interface reveals significant fluctuations in C and Cr elements. The width of the fluctuation region indicates the thickness of the carbide layer, and the thicker the carbide layer, the better the brazing alloy's wettability to the diamond. However, an excessively thick carbide layer will intensify the chemical corrosion of the catalyst elements in the brazing material on the diamond, destroying the diamond's own C atomic structure and reducing its mechanical properties. Figure 9 The exposure of diamond in the brazing process proves that the co-doping of Yb and Tb can improve the wettability of Ni-Cr brazing material for diamond and promote the interface reaction between the brazing material and diamond. However, if the co-doping content is too high, the exposure of diamond may be reduced and the thickness of the carbide layer may be too thick, which will aggravate the chemical corrosion of the brazing material.

[0059] like Figure 10 、 Figure 11 As shown, the brazing diamonds prepared in Example 7 and Comparative Example 4 were etched with aqua regia, and the microscopic morphology of the carbide morphology on the diamond surface was tested; Among them, the experimental steps of aqua regia etching are: put the diamond-matrix part of the brazing diamond into aqua regia solution and corrode until the matrix and the brazing layer wrapped around the diamond are removed, so that the carbide layer is completely exposed on the diamond surface.

[0060] according to Figure 10 It can be seen from the test results that a dense layer of carbide is formed on the surface of the diamond after etching with aqua regia. The carbide is formed by the diffusion of Cr atoms to the surface of the diamond after the solder melts, and reacts with the graphitized C atoms. Chromium-carbon compounds play a bridging role, and the generation of chromium-carbon compounds can reduce the thermal expansion coefficient mismatch problem between diamond and solder. Rare earth co-doping forms a relatively dense carbide, which alleviates stress concentration and crack formation to a certain extent. In particular, after brazing with the Ni-Cr CFA2 solder prepared in Example 2, there are no obvious cracks on the carbide surface and the size of the carbide is relatively small. The carbide is evenly distributed at the brazing joint, which plays a certain buffering role. With the continuous increase of the co-doping content, such as Figure 10(c) and (f), the size of the carbides continues to grow, and the length and number of cracks increase. This may be because the brazing filler metal has a high wettability, forming coarse carbides. Due to the existence of residual stress, the cracks extend to the entire carbide layer. Figure 11 The test results show that the carbide morphology on the diamond surface brazed with Ni-Cr1 braze material is mainly composed of coarse lamellar carbides, and wide micro cracks appear on the carbide surface and extend to the entire carbide layer; the carbide morphology on the diamond surface brazed with Ni-Cr2 braze material becomes finer, but the number of micro cracks on the carbide surface is relatively large; the carbide surface cracks on the diamond surface brazed with Ni-Cr3 braze material are longer, which is caused by the large residual stress between the diamond abrasive and the brazing alloy. The cracks in the carbide are prone to further cracking, causing the brazing alloy to lose its ability to hold the diamond abrasive.

[0061] In summary, the carbides on the surface of undoped and single-doped diamonds exhibit coarse, lamellar shapes, and the microcracks on the carbide surface are long and numerous. Rare earth co-doping effectively reduces the size of the carbides. The finer carbides can effectively alleviate residual stress in the brazed joint, thereby effectively reducing the degree of cracking in the carbide layer and improving the bond strength between the brazing filler metal and the diamond abrasive.

[0062] like Figure 12 、 Figure 13 As shown, Raman spectroscopy tests were performed on the brazing materials brazed diamond prepared in Example 7 and Comparative Example 4 respectively; according to Figure 12 The test results show that the graphitization degree of diamond brazed by Ni-Cr CFA2 brazing filler metal is the lowest, and the carbon element structure in the diamond crystal structure is stable, mainly in the form of sp 3 Hybrid bonding, no significant sp 3 To sp 2 Hybrid transformation shows that the hardness and wear resistance of diamond are maintained under Ni-Cr CFA2 brazing. After rare earth co-doping, the brazed diamonds all show a scattering peak (G peak) of graphite structure. This may be because rare earth co-doping improves the wettability of the brazing material, making the brazing material climb higher on the diamond surface. The Ni and Fe elements in the brazing material act as catalyst elements to accelerate the sp 3 To sp 2 Hybridization transformation results in the appearance of different degrees of graphite structure characteristic scattering peaks in the test results. Figure 13The test results show that the G peak intensity of diamond brazed with Ni-Cr1 brazing filler metal is higher, indicating that diamond has undergone serious graphitization and the thermal damage to diamond is more serious; diamond brazed with Ni-Cr2 brazing filler metal still has a high tendency to graphitize, and diamond graphitization will seriously weaken the mechanical properties of diamond; the G peak intensity of diamond brazed with Ni-Cr3 brazing filler metal is lower, but still more obvious, indicating that the internal atomic structure of diamond is composed of sp 3 The hybrid structure gradually shifts to sp 2 The hybrid structure changes and diamond is affected by graphitization.

[0063] In summary, rare earth co-doping can effectively alleviate the catalytic effect of catalyst elements in the brazing alloy on diamond graphitization compared with undoped and single doping. Rare earth Yb and Tb work together with Ni elements to slow down the carbon atoms on the diamond surface from sp 3 To sp 2 The hybrid transformation greatly reduces the graphitization of diamond and retains the mechanical properties of diamond.

[0064] like Figure 14 As shown, the static pressure strength test was carried out on the diamond brazed with Yb and Tb co-doped alloy brazing filler metal prepared in Example 7 and the diamond brazed with Ni-Cr1 brazing filler metal prepared in Comparative Example 4; according to Figure 14 The test results show that the static compressive strength of the diamond brazed with Ni-Cr 1 brazing filler metal, prepared in Comparative Example 4, is 2014.3 MPa. The static compressive strength of diamond brazed with Ni-Cr CFA1, Ni-Cr CFA2, and Ni-Cr CFA3 brazing fillers is approximately 3000 MPa or more, reaching 73% of the original diamond, and the diamond has good mechanical properties. Among them, the static compressive strength of diamond brazed with Ni-Cr CFA3 and Ni-Cr CFA6 brazing fillers is lower. These two brazing fillers have a high degree of graphitization, and the carbon-carbon covalent bonds in the diamond structure are transformed from three-dimensional sp³ bonds to two-dimensional sp² planar layered structures. The sp² bonds in the graphite structure are weak, and the bonding force between atoms is far less strong than the sp³ bonds in diamond. The integrity of the crystal structure is destroyed, making the diamond more fragile and resulting in a reduction in static compressive strength.

[0065] In summary, the static pressure strength of diamond brazed with rare earth co-doped brazing filler metal is about 50% higher than that of diamond brazed with undoped rare earth brazing filler metal. It can be seen that rare earth co-doping reduces the thermal damage of diamond and retains the mechanical properties of diamond.

[0066] like Figure 15As shown, the wear resistance of the brazing diamonds brazed with brazing filler metals prepared in Example 7 and the comparative example was tested using a MM-W1B vertical universal friction and wear testing machine, wherein the load was 100 N, the rotation speed was 200 r / min, and the grinding time was 30 min; according to Figure 15 The test results show that Figure 15 (a) The diamond abrasive grains were broken in a small area. This kind of breakage had little effect on the diamond abrasive grains, and most of the cutting edges were retained, so the diamond sample could continue to perform the grinding function. Figure 15 The morphology of the diamond abrasive grains in (b) and (e) is basically intact. This is because the thermal damage to the diamond is relatively small, which greatly preserves the mechanical properties of the diamond. This allows the diamond to perform its grinding function without breaking or shattering on a large scale. Figure 15 (d) The fracture form is plowing, in which diamond abrasive grains produce staggered grooves and furrows in the fracture area. Figure 15 (c) and (f) are intergranular fractures. This is caused by the high impact and stress the diamond abrasives experience during the grinding process, as well as residual stress within the diamond abrasives. The cracks propagate along the interface between the diamond and the brazing material. In this case, the diamond abrasives essentially lose their grinding function, significantly impacting the processing efficiency and service life of the diamond.

[0067] Figure 16 The friction coefficient of diamond abrasives and the amount of alumina ceramic removed are the results. In the initial grinding stage, the cutting edge of the diamond abrasive surface is sharp, and the contact area with the alumina ceramic of the grinding sample is small. As the grinding progresses, local wear and crack expansion lead to an increase in contact area and an increase in local roughness, thereby increasing friction resistance and increasing the friction coefficient. As the grinding time progresses, factors such as diamond wear, interface temperature, chip generation and shedding reach a dynamic balance. At this time, the friction coefficient begins to decrease and finally stabilizes. The average friction coefficient in the stable stage after a grinding time of 300 s was calculated separately. Figure 16 The test results show that diamond brazed with Ni-Cr CF2 braze exhibits the lowest average friction coefficient of approximately 0.092, and the flattest friction curve, demonstrating excellent wear resistance. The removal of alumina ceramics was also statistically analyzed, which indirectly reflects the mechanical properties of diamonds. Diamond brazed with Ni-Cr CF2 braze exhibits low graphitization and excellent mechanical properties, resulting in excellent machining performance when grinding alumina ceramics, with a maximum removal of 45.8 mg.

[0068] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a Yb and Tb co-doped alloy solder, characterized in that: The following steps are involved: Step (1): grinding nickel, chromium, boron, silicon, iron, terbium, and ytterbium, ultrasonically treating them, taking them out, and drying them to obtain a pre-dried alloy raw material; Step (2): melting the pre-dried alloy raw material, cooling it in the furnace after melting, and taking it out to obtain a brazing ingot; Step (3): cutting the solder ingot to obtain a flake alloy solder, polishing, and drying to obtain a Yb and Tb co-doped alloy solder; The mass percentage of each component in the Yb and Tb co-doped alloy solder is: 12-13% chromium, 3-4% boron, 3-4% silicon, 4-5% iron, 0.5-2% terbium, 0.5-1.5% ytterbium, and the balance is nickel.

2. The method for preparing a Yb and Tb co-doped alloy solder according to claim 1, characterized in that: In the step (1), the ultrasonic treatment operation includes: in an ultrasonic cleaning machine, ultrasonically oscillating and cleaning in acetone for 10-15 minutes, and then transferring to ethanol and continuing ultrasonic treatment for 5-10 minutes.

3. The method for preparing a Yb and Tb co-doped alloy solder according to claim 1, characterized in that: In the step (2), the order of adding the pre-dried alloy raw materials is as follows: placing them in the copper crucible of the smelting furnace according to the gradient distribution of the element melting points.

4. The method for preparing a Yb and Tb co-doped alloy solder according to claim 1, characterized in that: In the step (2), the smelting conditions are: using a mechanical pump to pump a low vacuum to 1×10 -1 Pa, and then use a molecular pump to draw a high vacuum to 3×10 -3 Pa, turn off the molecular pump, and melt the alloy in an Ar gas atmosphere at a pressure of -0.05 MPa; the melting operation is as follows: turn on the melting power heating switch to make the voltage between 60-80 V, then perform high-frequency arc ignition to control the heating current in the melting furnace to 250-280 A, and repeatedly turn the alloy ingot over and remelt it 3-4 times to make its composition uniform.

5. The method for preparing a Yb and Tb co-doped alloy solder according to claim 1, characterized in that: In the step (3), the specifications of the sheet alloy solder are: length 12-15 mm, thickness 150-180 μm. 6 . A Yb and Tb co-doped alloy solder prepared by the method for preparing a Yb and Tb co-doped alloy solder according to any one of claims 1 to 5 .

7. A brazing process for Yb and Tb co-doped alloy solder, characterized in that: The brazing process includes the following steps: Take a No. 45 steel block, apply an adhesive on the brazing surface of the steel block, spread the Yb and Tb co-doped alloy brazing material according to claim 6 on the brazing surface coated with the adhesive, and then arrange diamond abrasives in an orderly manner on the upper surface of the flaky alloy brazing material. Place the steel block, flaky alloy brazing material and diamond abrasives in sequence from bottom to top, dry, braze connection, keep warm, cool, cool with the furnace, and take out to obtain Yb and Tb co-doped alloy brazing material brazing diamond.

8. A brazing process for a Yb and Tb co-doped alloy solder according to claim 7, characterized in that: The insulation conditions are: at a vacuum degree of 4×10 -4 Pa, heat to 1080°C at a heating rate of 10°C / min and keep warm for 5-8 minutes.

9. The brazing process of a Yb and Tb co-doped alloy solder according to claim 7, characterized in that: The cooling condition is: cooling to 500° C. at a cooling rate of 5° C. / min.

10. Brazing diamond with a Yb and Tb co-doped alloy brazing material prepared by the brazing process for the Yb and Tb co-doped alloy brazing material according to any one of claims 7 to 9.

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