A high-efficiency grinding boron-containing high-entropy alloy combined with diamond superhard composite material and its preparation method and application

Abstract

The present invention belongs to the technical field of diamond composite materials, and discloses a high-efficiency grinding boron-containing high-entropy alloy bonded diamond composite material, a preparation method, and an application thereof. The composite material is composed of 75-95 vol.% of a boron-containing high-entropy alloy binder phase and 5-25 vol.% of diamond abrasive particles; the binder phase powder used is prepared by mechanical alloying of iron powder, cobalt powder, chromium powder, nickel powder, and amorphous boron powder for doping. The composite material has the following advantages: the present invention uses amorphous boron powder with higher activity as a raw material, which can shorten the manufacturing cycle and accurately determine the boron content. The prepared composite material has excellent interface bonding and friction and wear properties; compared with doping with metal elements with large atomic radius, boron doping avoids the aggravation of segregation phase, and boron solid solution strengthening more effectively improves the wear resistance of the diamond composite material and the grinding efficiency of ceramic balls. It can be used to prepare tools such as diamond cutter wheels or saw blades for efficiently processing hard materials such as ceramics.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of diamond composite materials, and particularly relates to a high-efficiency grinding boron-containing high-entropy alloy combined with diamond superhard composite material, and a preparation method and application thereof. Background Art

[0002] With the rapid development of high-end fields such as aerospace, photovoltaics, and communications, a large number of hard and brittle materials such as cemented carbide, semiconductors, and especially new materials such as advanced ceramics have been widely used. Their corresponding difficult-to-process characteristics have also put forward higher requirements for the design of processing tools. Superhard abrasive tools made of metal-bonded diamond abrasives are widely used in the grinding of hard and brittle materials due to their high bonding strength, good formability, and long service life (Metals, 8(5)(2018):307). The performance of the metal bond has an important influence on the life and grinding efficiency of diamond tools.

[0003] Currently, metal binders are primarily based on Co, Fe, Cu, and Ni. However, traditional single-component alloys are prone to forming harmful products such as complex intermetallic compounds, making it difficult to maintain structural stability. Their strength, wear resistance, and high-temperature resistance make them difficult to meet the requirements for efficient grinding of hard and brittle materials. High-entropy alloys are a new type of multi-component alloy with a simple structure. Their use as a binder for superhard abrasive tools simplifies composition while achieving solid solution strengthening with multiple elements. They offer high strength, wear resistance, high-temperature resistance, and a wide range of formulation adjustments.

[0004] In recent years, there have been relevant research reports on high entropy alloy-diamond composite materials. For example, Li Jianmin of Yanshan University mixed CuZnFeTiAl and CuCrFeNiAl high entropy alloy powders with body-centered cubic (BCC) main phase with diamond to prepare diamond composite materials, and the corresponding bending strength was as high as 560MPa and 668.35Mpa (Li Jianmin. Preparation and Performance Research of High Entropy Alloy Binder Superhard Abrasive Materials [D]. Yanshan University. 2018). Guo Hongkai et al. also studied Al with body-centered cubic (BCC) main phase. 1.5 CoNiFeCuZnMnY 0.1 and Al 1.5 CoNiFeCuZnY 0.1A high-entropy alloy (HEA) was mixed with diamond and sintered using conventional hot pressing. Due to the difference in thermal expansion coefficients between the HEA and diamond, as well as their poor wettability, the composites exhibited flexural strengths of 316 MPa and 234 MPa, respectively (Guo Hongkai. Research on High-Entropy Alloy Binders for Diamond Tools [D]. Yanshan University. 2016). Further grinding tests on ceramic materials were not conducted. Furthermore, the hard and brittle BCC-based HEA combined with the hard diamond particles resulted in a brittle fracture during tool fabrication (Li Kenan. Research on High-Speed ​​Dynamic Behavior of Ultra-Thin Grinding Wheels and Design of New Binders [D]. Yanshan University. 2019).

[0005] Compared with high entropy alloys with refractory metal main elements and BCC main phase, the face-centered cubic (FCC) phase FeCoCrNi high entropy alloy system has the advantages of good room temperature plasticity and high fracture toughness, and its strength and wear resistance can be improved by adding BCC elements such as Al, Ti, Mo with large atomic radius through substitution and solid solution. For example, Zhang et al. from Central South University used spark plasma sintering (SPS) to prepare Fe 24.1 Co 24.1 Cr 24.1 Ni 24.1 Mo 3.6 High entropy alloy-diamond composite materials, and applied them to the processing of Si3N4 superhard ceramics. They found that the bonding phase of the composite material sintered at 950℃ is composed of FCC main phase and chromium-rich BCC phase. The interstitial strengthening effect of C at the interface structure makes the material show excellent mechanical properties: hardness of 630HV, transverse fracture strength of 1310MPa, which is 1.5-2 times higher than the existing diamond composite materials (International Journal of Refractory Metals and Hard Materials, 86(2019):105109). However, Mo has limited solid solubility in FeCoCrNi high entropy alloys. For example, Wang et al. prepared FeCoCrNiMo by gas atomization and SPS. 0.2 It was found that Cr and Mo-rich σ phase precipitated from the metastable FCC matrix (Materials Science & Engineering A, 689 (2017): 233-242). Zhang et al. prepared Fe 24.1 Co 24.1 Cr 24.1 Ni 24.1 Mo 3.6 (FeCoCrNiMo 0.15In the composite material of )-diamond, due to the formation of segregated σ phases such as Cr-rich phase and Mo-rich phase, the wear performance and flexural strength of the composite material decrease, and the wear rate increases. (Entropy, 20(12)(2018):924). Therefore, if the phenomenon of aggravated σ phase precipitation caused by doping elements such as Mo can be avoided, and other elements with higher solid solubility can be introduced to improve the performance of the alloy while maintaining the advantages of the single face-centered cubic high entropy alloy itself, it will have a positive effect on improving the performance of the composite material and the grinding efficiency of ceramics such as Si3N4.

[0006] Boron, as an ideal dopant, can significantly improve the mechanical properties of traditional alloys and high entropy alloys. For example, the document Acta Metall, 33 (2) (1985): 213-229 discloses that by adding boron to Ni3Al, the yield strength can be increased by 242-387 MPa per atomic percentage, and its ductility can also be significantly improved. The document Rare Met. Mater. Eng, 44 (6) (2015): 1418-1422 studies the effect of different boron contents on the microstructure, hardness and wear resistance of FeCoCrNiB HEA coatings. The results show that the addition of boron significantly improves the hardness and wear resistance. The document Rare Met. Mater. Eng. 46 (9) (2017): 2639-2644 discloses that when the molar content of boron is less than 0.25, FeCrNiCoMnB 0.25 Consists of a single FCC phase.

[0007] However, applying boron as a dopant to high-entropy alloy-diamond composites still presents process challenges that need to be addressed. Currently, most research on preparing boron-containing high-entropy alloys uses arc melting and laser cladding methods, with boron added in the form of ferroboron powder. For example, the mass fractions of the ferroboron powder in the literature (Heat Treatment of Metals, DOI: 10.13251 / j.issn.0254-6051.2016.09.018) are as follows: 20% B, 0.5% C, 4.0% Si, 0.2% P, 0.5% Al, and the balance Fe. While arc melting is feasible for preparing high-entropy alloy-diamond composites, patent CN114561565B, for example, uses arc melting to prepare diamond particle-reinforced high-entropy alloy composites containing any of four, five, or six of the seven refractory metal elements: Ti, Zr, Hf, Nb, Ta, W, and Mo. However, this method of adding boron to ferroboron powder introduces impurity elements such as C, Si, and P, and the energy consumption of the smelting process is very high. The cast alloy prepared by smelting has large grain size, serious internal component segregation, and many defects such as voids and shrinkage cavities, which also affects the performance of the cast alloy. It is not suitable for preparing composite materials with high-efficiency grinding performance.

[0008] In addition to arc melting, powder metallurgy is currently more commonly used to prepare high-entropy alloy-diamond composite materials. For example, patent CN114134381 B, patent application number: CN201811116153.7 uses an atomization method to prepare CuNiCoCr and CuNiFeSnTi powders. Although the atomization method has the characteristics of low oxygen content, good uniformity and low pollution, it is also found that there are pores inside the powder in this method. Therefore, the powder prepared by the atomization method still needs to be mechanically ball milled to eliminate atomization defects and refine the grains, thereby improving the density of the sintered block. For example, the document Intermetallics, 68 (2016): 16-22 and patent CN107663607B use gas atomization followed by mechanical alloying to prepare high-entropy alloy powder. On the other hand, for the atomization method, the required materials must be prepared in the form of ingots before atomization and then smelted into alloy melts by induction furnaces, which complicates the preparation process and increases the cost of the process. For alloys doped with boron, they still need to be added in the form of ferroboron blocks. Compared with the atomization method, the use of mechanical ball milling to prepare high-entropy alloy powder can avoid the requirements of the preparation method on the form of elemental raw materials, shorten the powder synthesis cycle, reduce costs, and provide better versatility and timeliness for the preparation of various alloys and tools (reference metals, 10 (9) (2020): 1186). However, since the melting point of boron is 2076 ° C and the activity of crystalline boron is not high, the time required for mechanical ball milling after adding boron element will also be relatively long. Patent CN112342418B uses the ball milling time and method of first ball milling at a speed of 150 r / min for 8 hours and then at a speed of 300 r / min for 60-65 hours after adding boron to the high-entropy alloy. Summary of the Invention

[0009] In order to address the shortcomings and deficiencies of the above-mentioned prior art, the primary purpose of the present invention is to provide a high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material. Due to the relatively high solid solubility of boron in the alloy and the resulting interstitial-strengthened alloy having higher comprehensive strength and toughness properties than the substitutional solid solution, it is proposed to apply boron-doped high-entropy alloys to the production of diamond tools to compensate for the defects of rapid increase in brittleness and easy formation of segregation phases caused by strengthening the existing high-entropy alloy binder by doping with large atomic radius metal elements.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned high-efficiency grinding boron-containing high entropy alloy combined with diamond superhard composite material; the metal base of the present invention is preferably FeCoCrNi-B XThe invention relates to a multi-component alloy. In order to reduce the influence of the preparation method on the element ratio, reduce process costs and shorten the manufacturing cycle, amorphous boron powder with higher activity is selected as the raw material. Boron-containing high-entropy alloy powder is prepared by mechanical alloying. After being uniformly mixed with diamond micropowder, the composite material is densified by spark plasma sintering (SPS) method with the advantages of fast heating rate, low temperature sintering and short sintering time. The performance of the binder and the bonding strength of the diamond / matrix interface are improved. In addition, the present invention can precisely adjust the B content by controlling the mass of the added amorphous boron powder during the mechanical alloying stage, optimize the friction and wear properties of the composite material through gap strengthening, and thus improve the processing efficiency and service life of the prepared superhard composite material.

[0011] Another object of the present invention is to provide an application of the above-mentioned high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material, which can be used to process hard and brittle materials such as Si3N4 and ZrO2 ceramics, and provide a new idea for the enhancement of the performance of diamond composite material binders and the selection and design of components.

[0012] The purpose of the present invention is achieved through the following technical solutions:

[0013] A high-efficiency grinding boron-containing high-entropy alloy combined with diamond superhard composite material consists of 75-95 vol.% of boron-containing high-entropy alloy binder phase powder and 5-25 vol.% of diamond abrasive grains.

[0014] Preferably, the composite material is composed of 80-90 vol.% of boron-containing high entropy alloy binder phase powder and 10-20 vol.% of diamond abrasive grains.

[0015] The boron-containing high-entropy alloy binder phase powder is prepared from powder raw materials with the following atomic ratios: iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder in an atomic ratio of Fe, Co, Cr, Ni and B of (20-30): (20-30): (20-30): (20-30): (1-10).

[0016] As a preferred embodiment, the boron-containing high entropy alloy binder phase powder is prepared from powder raw materials with the following atomic ratio: iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder with an atomic ratio of Fe, Co, Cr, Ni, and B of 1:1:1:1:x, where 0<x≤0.3.

[0017] Preferably, the purity of the iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder is ≥99.9%, and the particle size is 10-75 μm.

[0018] The diamond abrasive grains have a particle size of 45-300 μm; the diamond abrasive grains include at least one of uncoated diamond, tungsten-coated diamond and titanium-coated diamond.

[0019] The size range of the composite material is diameter 0mm<d≤100mm, and thickness 0<h≤20mm.

[0020] The composite material is used to process silicon nitride balls with a diameter of 5 mm, and the silicon nitride balls are worn to a diameter greater than 3 mm. Silicon nitride ceramics are used as dual balls, and a ball-on-disc friction and wear tester is used to perform a friction and wear test on the composite material in dry air. The loading load is 1000 g, the wear radius is 5 mm, the rotation speed is 1000 r / min, and the test time is 30 minutes. The friction coefficient of the composite material is measured to be less than 0.15.

[0021] The above-mentioned method for preparing a high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material comprises the following steps:

[0022] (1) placing a mixture of iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder into a cemented carbide tungsten carbide ball mill, and ball milling on an omnidirectional planetary ball mill for 10-50 h, a ball-to-material ratio of 4-10:1, a rotation speed of 200-1400 r / min, and passing through a 200 mesh sieve to obtain a boron-containing high entropy alloy binder phase powder;

[0023] (2) mixing the boron-containing high entropy alloy binder phase powder and diamond abrasive grains in a mixing drum for 20-60 min, loading the mixed raw materials into a graphite abrasive tool, and pre-pressing at a pressure of 2-5 MPa;

[0024] (3) Spark plasma sintering is performed with a sintering pressure of 10-30 MPa, a sintering temperature of 850-1000°C, a holding time of 300-600s, and a heating rate of 100-150°C / min to obtain a high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material.

[0025] The ball milling in step (1) is carried out under the protection of an inert gas; the average particle size of the obtained boron-containing multi-principal alloy binder phase powder is 15-72 μm.

[0026] The spark plasma sintering in step (3) is carried out in an argon atmosphere, and the gas pressure in the sintering furnace used is 15mbar-30mbar.

[0027] The above-mentioned high-efficiency grinding boron-containing high entropy alloy combined with diamond superhard composite material is used in preparing the working layer of diamond tools for high-efficiency grinding and cutting of superhard materials.

[0028] The present invention has the following advantages and effects compared to the prior art:

[0029] (1) The present invention mixes iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder, adopts mechanical alloying method to prepare boron-containing high entropy alloy powder, and combines diamond to prepare boron-containing high entropy alloy-diamond superhard composite material. The whole preparation method is simple, the manufacturing cycle is short, the controllability is high, and the prepared composite material has excellent interface bonding and diamond stability. Compared with the grinding performance degradation caused by the easy precipitation of σ precipitation phase caused by large atomic radius elements, the high entropy alloy doped with non-metallic boron elements of equal atomic ratio can avoid the aggravation of the precipitation phase caused by the addition of large atomic radius elements, thereby improving the performance of the metal binder and indirectly improving the wear resistance of the composite material and the processing removal rate of the ceramic balls.

[0030] (2) In the friction and wear test of Example 1 of the boron-containing high entropy alloy combined with diamond superhard composite material prepared by the present invention, the friction coefficient of the composite material is lower than 0.15, and the processed diameter of the Φ5mm Si3N4 ball is 3.048mm, which is larger than that of the comparative example 1, i.e., FeCoCrNiMo under the same preparation and test conditions. 0.15 The diameter of the Si3N4 ball corresponding to the high entropy alloy / diamond composite material was processed (2.544mm). The results show that the boron-containing high entropy alloy combined with the diamond composite material has higher grinding efficiency and can be used to prepare the working layer for grinding and cutting diamond tools.

[0031] (3) The following content is a comparison of some specific existing technologies for boron-containing high entropy alloys:

[0032] ① Document DOI: 10.27270 / d.cnki.gsxau.2021.000298. discloses the influence of B on the microstructure and mechanical properties of CoCrFeNi and CrFeNi2 multi-component alloys. However, this document adopts a melt-casting method to prepare high-entropy alloy blocks, and the raw material used is ferroboron blocks, which is different from the preparation method of the present invention and the elemental amorphous boron powder used as the raw material.

[0033] ② The patent application with publication number CN112342418B discloses a face-centered cubic boron-containing high-entropy alloy prepared by microwave sintering and its preparation method. Specifically, Fe, Co, Ni, Cu, and B metal powders are treated by mechanical alloying + microwave sintering. This patent application adds relatively more boron to generate borides, while the boron element of the present invention serves as a dopant and mainly plays a role in gap strengthening without generating borides. In addition, the creative point of this patent application is that microwave sintering is used for densification, which can refine the precipitated borides compared to the melt-casting method.

[0034] ③ Patent application with publication number CN110449580B discloses a powder metallurgy high-strength and toughness boron-containing high-entropy alloy material, its preparation method and application, specifically, Al, Fe, Ni, Co, Cr, B and Y powders are treated by mechanical alloying + ultracentrifugation + spark plasma sintering. The system of this patent application is that the main phase is body-centered cubic phase (BCC) + boride, which is different from the present invention; and this patent application has the steps of ultracentrifugation and ultrasonic treatment of the powder. The creative point is that the preparation method makes the precipitated boride phase small and without large-scale aggregation.

[0035] ④ Patent application with publication number CN104451351B discloses a method for adding rare earths to improve the strength and toughness of boron-containing high-entropy alloys. Specifically, a boron element with a molar fraction of 0.1 to 8% is added to the high-entropy alloy, and a rare earth element such as Y or Ce is added at 0.1 to 4%. Unlike the present invention, this patent application simultaneously adds boron and rare earth elements to the high-entropy alloy. The innovative point is that the addition of rare earth elements improves the strengthening effect of boron in the high-entropy alloy and reduces the precipitation content and size of coarse borides. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 These are the X-ray diffraction patterns of the phases of the molybdenum-containing high-entropy alloy bonded diamond composite material of Comparative Example 1 and the boron-containing high-entropy alloy bonded diamond superhard composite material of Example 1.

[0037] Figure 2 These are scanning electron microscope images of the molybdenum-containing high-entropy alloy bonded diamond composite material of Comparative Example 1 and the boron-containing high-entropy alloy bonded diamond superhard composite material of Example 1, where (a)-(b) are 100 times magnified surfaces of Comparative Example 1; (c)-(b) are 100 times magnified surfaces of Example 1.

[0038] Figure 3 This is an energy spectrum diagram of the interface between the binder and diamond in the molybdenum- and boron-containing high-entropy alloy bonded diamond superhard composite material prepared in Comparative Example 1 and Example 1.

[0039] Figure 4 This is a graph showing the change in friction coefficient versus sliding time in a friction and wear test between the composite materials prepared in Comparative Example 1 and Example 1 and Si3N4 balls with a diameter of 5 mm and the same mass, under a load of 1000 g and a friction stroke of 5 mm for 30 minutes.

[0040] Figure 5 These are scanning electron microscope images of the wear surfaces of the composite materials prepared in Comparative Example 1 and Example 1 after friction and wear tests; the wear surfaces of the composite materials in the figures: (a) is a 100-fold magnified surface of Comparative Example 1, and (c) is a 100-fold magnified surface of Example 1.

[0041] Figure 6It is a scanning electron microscope image of the wear surface of the processed Si3N4 balls corresponding to the composite materials prepared in Comparative Example 1 and Example 1 after the friction and wear test. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0043] Example 1

[0044] A boron-containing high-entropy alloy bonded diamond superhard composite material is prepared by mechanical alloying and spark plasma sintering. The raw materials of the boron-containing high-entropy alloy bonded diamond superhard composite material include 90 vol.% of boron-containing high-entropy alloy binder phase powder and 10 vol.% of diamond powder.

[0045] The method for preparing the boron-containing high-entropy alloy bonded diamond superhard composite material of this embodiment comprises the following steps:

[0046] High-purity elemental powder with a particle size of 50-75 μm was selected. Iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder were weighed in the ratio of 1:1:1:1:0.15 according to atomic percentage and placed in a WC carbide ball mill. The corresponding ball milling medium was WC carbide balls. The balls were placed in a QXQM-4 all-round planetary ball mill for ball milling. The time was set to 20 h, the mass ratio of balls to alloy powder was 10:1, and the rotation speed was 300 r / min. To prevent the oxidation of the powder by air, the entire powder preparation and powder extraction process was carried out in a glove box filled with high-purity argon.

[0047] The high entropy alloy powder after ball milling was sieved using a 200-mesh sieve, and then the high entropy alloy powder was mixed with 10 vol% of 70 / 80 mesh tungsten-coated diamond powder at a rate of 90 vol.%, loaded into a graphite abrasive, and pre-pressed at 2 MPa using a hydraulic press. It was then placed in a spark plasma sintering machine model FCT-D20 for sintering. The sintering pressure was 30 MPa, the sintering temperature was 950 ° C, the holding time was 480 s, and the heating rate was maintained at 100 ° C / min. During the sintering process, the argon pressure in the furnace was set to 30 mbar, and finally a boron-containing high entropy alloy (FeCoCrNiB) with a diameter of 30 mm was obtained. 0.15 ) combined with a diamond superhard composite material. The resulting composite block is polished and finally diamond-edged using a diamond grinding disc and silicon carbide sandpaper.

[0048] The boron-containing high entropy alloy (FeCoCrNiB 0.15) combined with diamond superhard composite materials are mainly composed of face-centered cubic phase (FCC) and diamond phase, such as Figure 1 shown.

[0049] according to Figure 2 The microstructure shown by electron microscope scanning shows that the shape of the diamond remains intact and no falling off occurs. Figure 3 It can be seen from the energy spectrum of the interface between the binder and the diamond that the binder matrix in this example is tightly bonded to the diamond, indicating an excellent bonding interface between the diamond and the matrix, and the diamond does not undergo graphitization after sintering.

[0050] Silicon nitride ceramics were used as the dual balls, and the ball-on-disc friction and wear tester model HT-1000 was used to test the boron-containing high entropy alloy (FeCoCrNiB 0.15 ) Friction and wear tests were carried out on a superhard diamond composite material with a loading load of 1000 g, a wear radius of 5 mm, and a rotational speed of 1000 r / min.

[0051] like Figure 4 As shown, the friction coefficient of the boron-containing high-entropy alloy combined with diamond superhard composite material prepared in this embodiment is 0.137. The running stage of the composite material prepared in this example is about 7 minutes during the test. Then, since the diamond abrasive grains remain relatively intact and exposed, the composite material continues to grind the surface of the silicon nitride ball before the end, and the friction coefficient maintains an upward trend.

[0052] After the friction test, Figure 5 and Figure 6 It can be seen that the high entropy alloy substrate is slightly worn, and the wear diameter of the processed Si3N4 ball is 3.048 mm, indicating that the matrix material of the boron-containing high entropy alloy combined with the diamond superhard composite material of the present invention has excellent grinding performance. Under the same conditions, it has higher grinding efficiency than the molybdenum-doped high entropy alloy binder diamond composite material.

[0053] Example 2

[0054] In order to further reflect the difference in binder performance between the composite materials of Example 1 doped with boron and Comparative Example 1 doped with molybdenum, the present invention prepared a boron-containing high-entropy alloy binder block without adding diamond particles and tested its friction and wear performance. Example 2 is the boron-containing high-entropy alloy binder of Example 1.

[0055] The boron-containing high entropy alloy binder block (i.e., FeCoCrNiB 0.15 A method for preparing a high entropy alloy block comprises the following steps:

[0056] High-purity elemental powder with a particle size of 50-75 μm was selected. Iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder were weighed in the ratio of 1:1:1:1:0.15 according to atomic percentage and placed in a WC carbide ball mill. The corresponding ball milling medium was WC carbide balls. The balls were placed in a QXQM-4 all-round planetary ball mill for ball milling. The time was set to 20 h, the mass ratio of balls to alloy powder was 10:1, and the rotation speed was 300 r / min. To prevent the oxidation of the powder by air, the entire powder preparation and powder extraction process was carried out in a glove box filled with high-purity argon.

[0057] The high entropy alloy powder after ball milling was sieved using a 200-mesh sieve, and the high entropy alloy powder was filled into a graphite grinding tool. After pre-pressing at 2 MPa using a hydraulic press, it was placed in a spark plasma sintering machine model FCT-D20 for sintering. The sintering pressure was 30 MPa, the sintering temperature was 950 ° C, the holding time was 480 s, and the heating rate was maintained at 100 ° C / min. During the sintering process, the argon pressure in the furnace was set to 30 mbar, and finally a FeCoCrNiB with a diameter of 20 mm was obtained. 0.15 High entropy alloy bulk.

[0058] Silicon nitride ceramics were used as the dual ball, and the ball-on-disc friction and wear tester model HT-1000 was used to test the FeCoCrNiB 0.15 The friction and wear test of the high entropy alloy block was carried out with a loading load of 1000 g, a wear radius of 5 mm, and a rotation speed of 300 r / min.

[0059] Test the FeCoCrNiB prepared in this example 0.15 The friction coefficient of the high entropy alloy block is 0.793, and the wear scar depth is 16.924 μm, which is significantly smaller than that of FeCoCrNiMo 0.15 The wear scar depth of 27.814 μm indicates that the high entropy alloy material of the present invention has better grinding performance.

[0060] Comparative Example 1

[0061] Other conditions are the same as those in Example 1, except that a Mo element with a large atomic radius is used to dope the high entropy alloy binder, including the following process steps:

[0062] High-purity elemental powder with a particle size of 50-75 μm was selected. According to atomic percentage, iron powder, cobalt powder, chromium powder, nickel powder and molybdenum powder were weighed in a ratio of 1:1:1:1:0.15 and placed in a WC carbide ball mill. The corresponding ball milling medium was WC carbide balls. The ball milling was carried out in a QXQM-4 all-round planetary ball mill. The time was set to 20 h, the mass ratio of balls to alloy powder was 10:1, and the rotation speed was 300 r / min. To prevent the oxidation of the powder by air, the entire powder preparation and powder extraction process was carried out in a glove box filled with high-purity argon.

[0063] The high entropy alloy powder after ball milling was sieved using a 200-mesh sieve, and then the high entropy alloy powder was mixed with 10 vol% of 70 / 80 mesh tungsten-coated diamond powder at a rate of 90 vol.%, loaded into a graphite abrasive, and pre-pressed at 2 MPa using a hydraulic press. The mixture was placed in a spark plasma sintering machine model FCT-D20 for sintering. The sintering pressure was 30 MPa, the sintering temperature was 950 ° C, the holding time was 480 s, and the heating rate was maintained at 100 ° C / min. During the sintering process, the argon pressure in the furnace was set to 30 mbar, and finally a molybdenum-containing high entropy alloy (FeCoCrNiMo) with a diameter of 30 mm was obtained. 0.15 ) combined with diamond composite materials. Diamond grinding discs and silicon carbide sandpaper are used to polish the composite blocks and finally diamond cutting.

[0064] Silicon nitride ceramics were used as the dual balls, and the ball-on-disc friction and wear tester model HT-1000 was used to test the wear of the molybdenum-containing high entropy alloy (FeCoCrNiMo 0.15 ) Friction and wear tests were carried out on diamond composite blocks with a loading load of 1000 g, a wear radius of 5 mm, and a rotational speed of 1000 r / min.

[0065] like Figure 1 As shown, the molybdenum-containing high entropy alloy (FeCoCrNiMo 0.15 ) bonded diamond composite materials are mainly composed of face-centered cubic phase (FCC) and diamond phase, in addition to some σ precipitated phases derived from Mo doping. Figure 2 It can be seen that after sintering, the shape of the diamond in this comparative example remains intact and no falling off occurs.

[0066] like Figure 4 As shown, the molybdenum-containing high entropy alloy (FeCoCrNiMo 0.15 ) The friction coefficient of the diamond composite material is 0.099, the running stage is about 4 minutes, and the friction coefficient rises slightly at the 15th minute, and then the friction coefficient remains stable before the end. Figure 5 and Figure 6It can be seen that after the friction test, the high-entropy alloy substrate undergoes obvious wear, and the diamond is broken after grinding. Some of the broken diamond abrasives are embedded in the substrate. The wear diameter of the processed Si3N4 ball is 2.544mm.

[0067] Comparative Example 2

[0068] The molybdenum-containing high entropy alloy binder of Comparative Example 1 is used. Other conditions are the same as those of Example 2, except that a Mo-doped high entropy alloy binder is used, including the following process steps:

[0069] High-purity elemental powder with a particle size of 50-75 μm was selected. According to atomic percentage, iron powder, cobalt powder, chromium powder, nickel powder and molybdenum powder were weighed in a ratio of 1:1:1:1:0.15 and placed in a WC carbide ball mill. The corresponding ball milling medium was WC carbide balls. The ball milling was carried out in a QXQM-4 all-round planetary ball mill. The time was set to 20 h, the mass ratio of balls to alloy powder was 10:1, and the rotation speed was 300 r / min. To prevent the oxidation of the powder by air, the entire powder preparation and powder extraction process was carried out in a glove box filled with high-purity argon.

[0070] The high entropy alloy powder after ball milling was sieved using a 200-mesh sieve, and the high entropy alloy powder was filled into a graphite grinding tool. After pre-pressing at 2 MPa using a hydraulic press, the powder was placed in a spark plasma sintering machine model FCT-D20 for sintering. The sintering pressure was 30 MPa, the sintering temperature was 950 ° C, the holding time was 480 s, and the heating rate was maintained at 100 ° C / min. During the sintering process, the argon pressure in the furnace was set to 30 mbar. Finally, a molybdenum-containing high entropy alloy binder block (i.e., FeCoCrNi Mo) with a diameter of 20 mm was obtained. 0.15 high entropy alloy bulk).

[0071] Silicon nitride ceramics were used as the dual balls, and the ball-on-disc friction and wear tester model HT-1000 was used to test the FeCoCrNiMo 0.15 The friction and wear test of the high entropy alloy block was carried out with a loading load of 1000 g, a wear radius of 5 mm, and a rotation speed of 300 r / min.

[0072] Test the FeCoCrNi Mo prepared in this comparative example 0.15 The friction coefficient of the high entropy alloy block is 0.824, and the wear scar depth is 27.814 μm.

[0073] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material, characterized by: The composite material is composed of 75-95 vol.% of boron-containing high entropy alloy binder phase powder and 5-25 vol.% of diamond abrasive grains; The boron-containing high entropy alloy binder phase powder is prepared from powder raw materials with the following atomic ratios: iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder in an atomic ratio of Fe, Co, Cr, Ni and B of 1:1:1:1:x, where 0<x≤0.3; The composite material is prepared according to the following steps: (1) Place a mixture of iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder into a cemented carbide tungsten carbide ball mill, and mill it on an omnidirectional planetary ball mill for 10-50 h, with a ball-to-material ratio of 4-10:1 and a rotation speed of 200-1400 r / min. Pass the mixture through a 200-mesh sieve to obtain a boron-containing high entropy alloy binder phase powder. (2) Mix the boron-containing high-entropy alloy binder phase powder and diamond abrasive grains in a mixing drum for 20-60 min, load the mixed raw materials into a graphite abrasive tool, and pre-press at a pressure of 2-5 MPa; (3) Spark plasma sintering was performed with a sintering pressure of 10-30 MPa, a sintering temperature of 850-1000 °C, a holding time of 300-600 s, and a heating rate of 100-150 °C / min to obtain a high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material.

2. The high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material according to claim 1, characterized in that: The purity of the iron powder, cobalt powder, chromium powder, nickel powder and amorphous boron powder are all ≥99.9%, and the particle size is 10-75 μm.

3. The high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material according to claim 1, characterized in that: The diamond abrasive grains have a particle size of 45-300 μm; the diamond abrasive grains include at least one of uncoated diamond, tungsten-coated diamond and titanium-coated diamond.

4. The high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material according to claim 1, characterized in that: The size range of the composite material is a diameter of 0 mm < d ≤ 100 mm and a thickness of 0 < h ≤ 20 mm.

5. The high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material according to claim 1, characterized in that: The composite material was used to process silicon nitride balls with a diameter of 5 mm, and the silicon nitride balls were worn to a diameter greater than 3 mm. Silicon nitride ceramics were used as dual balls, and a ball-on-disc friction and wear tester was used to conduct a friction and wear test on the composite material in dry air. The loading load was 1000 g, the wear radius was 5 mm, the rotation speed was 1000 r / min, and the test time was 30 min. The friction coefficient of the composite material was measured to be less than 0.

15.

6. The high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material according to claim 1, characterized in that: The ball milling in step (1) is carried out under the protection of an inert gas; the average particle size of the obtained boron-containing high entropy alloy binder phase powder is 15-72 μm.

7. The high-efficiency grinding boron-containing high-entropy alloy bonded diamond superhard composite material according to claim 1, characterized in that: The spark plasma sintering in step (3) is carried out in an argon atmosphere, and the gas pressure in the sintering furnace used is 15 mbar-30 mbar.

8. Use of the high-efficiency grinding boron-containing high entropy alloy combined with diamond superhard composite material according to any one of claims 1 to 5 in preparing a working layer of a diamond tool for high-efficiency grinding and cutting of superhard materials.

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