Ultrafine pre-alloyed powder, method for producing the same, and diamond sinter

Abstract

The application discloses superfine pre-alloy powder, a preparation method thereof and a diamond sintered body. The superfine pre-alloy powder comprises the following components in percentage by weight: 30-50% of iron, 20-30% of cobalt, 25-40% of copper and 0.5-1% of phosphorus. The preparation method comprises the following steps: dissolving soluble acid salts of iron, cobalt and copper in water to prepare a metal ion solution; mixing the phosphate and the metal ion solution to prepare a mixed system; adding a weak base to the mixed system and stirring to generate a precipitate; washing the precipitate with water and then drying the precipitate to obtain a precursor; reducing the precursor to obtain the superfine pre-alloy powder; and the phosphate is at least one of iron phosphate, cobalt phosphate and copper phosphate. By introducing the appropriate amount of phosphorus element, the sintering temperature is reduced, the density of more than 98% can be achieved under the pressureless sintering at a temperature lower than 1000 DEG C, and the strength and hardness of the product are improved.

Description

Technical Field

[0001] This invention belongs to the field of alloy powder technology, specifically relating to an ultrafine pre-alloyed powder, its preparation method, and a diamond sintered body. Background Technology

[0002] Traditionally, diamond tool matrix materials are produced using a hot-pressing sintering process, where metal powder is subjected to high temperature and pressure treatment in a graphite mold to achieve high density. However, this process has the following drawbacks: it requires expensive graphite molds, increasing manufacturing costs; the tool shape design is not flexible due to mold limitations; the process is complex, requires sophisticated equipment, and consumes a lot of energy.

[0003] Free sintering (also known as pressureless sintering) is an advanced forming technology that requires no molds or external pressure. It relies on heat to induce atomic diffusion and bonding between particles, allowing for the production of complex-shaped parts without external pressure or molds. Compared to traditional hot-pressing sintering, it offers lower equipment costs, higher production efficiency, and greater operational flexibility. However, free sintering requires extremely high levels of powder sintering activity and densification, and currently, it still faces significant challenges.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an ultrafine pre-alloyed powder, its preparation method, and a diamond sintered body. The ultrafine pre-alloyed powder can be used to prepare a sintered body with a density of over 98% under pressureless sintering.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] An ultrafine pre-alloyed powder comprises at least the following components by weight percentage: 30%–50% iron, 20%–30% cobalt, 25%–40% copper, and 0.5%–1% phosphorus.

[0008] In one or more embodiments of the present invention, the Fisher particle size is less than or equal to 2 μm.

[0009] Another specific embodiment of the present invention provides the following technical solution:

[0010] A method for preparing ultrafine pre-alloyed powder includes the following steps:

[0011] A metal ion solution is prepared by dissolving soluble acidic salts of iron, cobalt, and copper in water.

[0012] A mixed system is prepared by mixing phosphate and metal ion solutions;

[0013] Heat the mixture to 40℃~60℃, add a weak base, and stir to react and form a precipitate.

[0014] The precipitate was washed with water and then dried to obtain the precursor.

[0015] The precursor was reduced to obtain ultrafine pre-alloyed powder;

[0016] The phosphate is at least one of iron phosphate, cobalt phosphate, and copper phosphate.

[0017] In one or more embodiments of the present invention, the particle size of the phosphate is 0.5 μm to 2 μm.

[0018] In one or more embodiments of the present invention, the weak base is at least one of sodium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium carbonate, and ammonia water.

[0019] In one or more embodiments of the present invention, when a weak base is added to the mixed system, the amount of weak base added is 5% to 10% in excess, based on the amount of weak base required for the stoichiometric ratio in the precipitate.

[0020] In one or more embodiments of the present invention, the total metal ion concentration in the metal ion solution is 60 g / L to 180 g / L.

[0021] In one or more embodiments of the present invention, the drying temperature is 120°C to 160°C and the drying time is 6h to 8h.

[0022] In one or more embodiments of the present invention, the reduction is carried out in a hydrogen atmosphere at a temperature of 500°C to 700°C for 4 to 6 hours, with a hydrogen volume flux of 0.03 m / s to 0.05 m / s.

[0023] Another specific embodiment of the present invention provides the following technical solution:

[0024] A diamond sintered body is prepared by using at least the above-mentioned ultrafine pre-alloyed powder or ultrafine pre-alloyed powder obtained by the above-mentioned method for preparing ultrafine pre-alloyed powder.

[0025] Compared with the prior art, the present invention introduces a specific amount of phosphorus element to lower the melting point of alloy powder, thereby reducing the sintering temperature. It can use a pressureless sintering process to prepare diamond sintered bodies with a density of over 98%, and can also improve the hardness and strength of diamond sintered bodies. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the preparation process of ultrafine pre-alloyed powder in one embodiment of the present invention;

[0028] Figure 2 This is a scanning electron microscope image of the ultrafine pre-alloyed powder in Example 1 of the present invention;

[0029] Figure 3 This is a second scanning electron microscope image of the ultrafine pre-alloyed powder in Example 1 of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0031] Diamond tools are primarily manufactured by mixing metal powder with diamond particles and then using a hot-pressing sintering process (heating and pressurizing simultaneously). Since diamond particles are composed of carbon, they cannot withstand temperatures exceeding 1000°C, as this would cause them to graphitize. Therefore, the traditional process uses hot-pressing sintering, where the mixture of metal powder and diamond is placed in a graphite mold and heated and pressurized in a hot-pressing sintering machine to form a product with a density exceeding 98%. However, hot-pressing is energy-intensive, has low production efficiency, and consumes a large amount of graphite molds. Therefore, pressureless sintering has become the development direction.

[0032] Pressureless sintering only requires cold pressing with steel molds to achieve a density of over 98% in a sintering furnace without the need for pressure. However, the iron-cobalt-copper powders used in previous studies require high sintering temperatures due to their high melting points, making it impossible to achieve a density of over 98% under conditions of no pressure and below 1000℃. Therefore, they cannot be directly used in pressureless sintering processes.

[0033] This invention introduces an appropriate amount of phosphorus to lower the melting point of the powder, thereby reducing the sintering temperature. In pressureless sintering, a density of over 98% can be achieved at a sintering temperature below 1000℃, effectively reducing energy consumption while ensuring product quality.

[0034] One specific embodiment of the present invention provides an ultrafine pre-alloyed powder, comprising at least the following components by weight percentage: 30%–50% iron, 20%–30% cobalt, 25%–40% copper, and 0.5%–1% phosphorus.

[0035] Specifically, in terms of composition design, iron and copper are used as the main elements, providing good basic properties while being relatively inexpensive, thus reducing costs. Additionally, cobalt is used for solid solution strengthening of the iron and copper. However, it is difficult to achieve a density of over 98% below 1000℃ using only iron-cobalt-copper ternary alloys for pressureless sintering. Existing methods add low-melting-point metals such as tin to lower the sintering temperature, but the addition of tin reduces the product's strength. This invention, by adding an appropriate amount of phosphorus, not only lowers the melting point of the powder, thus reducing the sintering temperature, but also allows the phosphide to achieve a liquid-phase sintering effect, resulting in better particle fusion and dispersion strengthening, thereby further improving the hardness and strength of the sintered product.

[0036] Regarding the phosphorus content, if the content is too low, the sintering temperature will not decrease significantly and will not be able to improve the sintering density of the final product. If the content is too high, the toughness of the sintered product will be relatively low, thereby reducing the product quality.

[0037] Furthermore, the Fehling particle size is less than or equal to 2 μm.

[0038] Specifically, diamond graphitizes during high-temperature sintering, which reduces its tool performance. Therefore, it needs to be sintered at a lower temperature to densify it and prevent graphitization. The finer the powder, the higher the sintering activity, and the lower the sintering temperature. This invention ensures the sintering effect by controlling the Fisher particle size of the pre-alloyed powder.

[0039] More specifically, the higher the Fisher particle size of the pre-alloyed powder, the higher the sintering temperature is required. However, high sintering temperatures can cause diamond to graphitize and lose its function. By controlling the Fisher particle size to within 2μm, it can be sintered and densified at a lower temperature, which can ensure that the matrix after sintering has sufficient density and that the diamond will not graphitize.

[0040] Another specific embodiment of the present invention provides a method for preparing ultrafine pre-alloyed powder, including steps 1-4.

[0041] Step 1: Dissolve soluble acidic salts of iron, cobalt, and copper in water to prepare metal ion solutions.

[0042] Specifically, the soluble acidic salts of iron are at least one of iron sulfate, nitrate, and chloride; the soluble acidic salts of cobalt are at least one of iron sulfate, nitrate, and chloride; and the soluble acidic salts of copper are at least one of iron sulfate, nitrate, and chloride. The total metal ion concentration in the metal ion solution is 60 g / L to 180 g / L.

[0043] Step 2: Mix the phosphate and the first solution to form a mixed system.

[0044] Specifically, the phosphate is at least one of iron phosphate, cobalt phosphate, and copper phosphate. These types of phosphates are insoluble in water and are dispersed in a mixed system.

[0045] Furthermore, the phosphate particle size is 0.5 μm to 2 μm. By controlling the phosphate particle size, on the one hand, it is beneficial to obtain pre-alloyed powder with a Fisher particle size of less than or equal to 2 μm; on the other hand, during the subsequent precipitation process, the precipitate and phosphate can be better mixed, allowing the phosphate to be evenly distributed among other metal elements, thereby forming a more uniform phosphorus-containing alloy phase during the subsequent reduction and sintering processes.

[0046] Step 3: Heat the mixture to 40℃~60℃, add a weak base, and stir to react and generate a precipitate.

[0047] Specifically, the stirring speed is 60 r / min to 120 r / min, and the weak base is at least one of sodium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium carbonate, or ammonia. When using it, the weak base (such as sodium carbonate, ammonium bicarbonate, ammonium oxalate, or ammonium carbonate) is prepared as an aqueous solution with a mass concentration controlled at 40 g / L to 120 g / L. After the weak base is added to the mixed system, acid-base neutralization produces a corresponding coprecipitate. Based on the required amount of weak base according to the stoichiometric ratio of the precipitate, an excess of 5% to 10% of the weak base is actually added to promote the precipitation of all metal ions.

[0048] The phosphate used in this invention is insoluble in water and does not react with the aforementioned weak bases under normal pressure. Upon addition of the weak base, it reacts with metal ions to form a precipitate. Because the precipitate forms within the system, it is evenly distributed with the phosphate, resulting in a uniform distribution of phosphorus among the other metal elements in the final pre-alloyed powder. This effectively lowers the sintering temperature of the pre-alloyed powder while maintaining its performance. Furthermore, even if the phosphate reacts with the aforementioned weak bases, the reaction is only mild and minimal. Considering this factor, the amount of phosphate added to the second solution can be appropriately increased to compensate for the loss caused by the reaction with the weak base, ensuring that the final pre-alloyed powder contains the required phosphorus content.

[0049] Step 4: Wash the precipitate with water and then dry it to obtain the precursor.

[0050] Specifically, the precipitate obtained in step 3 is washed with water until the chloride ion concentration in the filtrate is less than 50 ppm, and then dried at 120℃~160℃ for 6h~8h. After drying, the coprecipitate forms the corresponding metal oxide, and the metal oxide and phosphate together constitute the precursor.

[0051] Step 5: Reduce the precursor to obtain ultrafine pre-alloyed powder.

[0052] Specifically, the reduction is carried out in a hydrogen atmosphere at a temperature of 500℃ to 700℃ for 4 to 6 hours, with a hydrogen volume flux of 0.03 to 0.05 m / s. During this process, the metal oxides in the precursor are reduced, and simultaneously, the phosphate is reduced, with phosphorus diffusing into other metal elements to achieve alloying.

[0053] Another specific embodiment of the present invention provides a diamond sintered body, which is prepared by at least the above-mentioned ultrafine pre-alloyed powder.

[0054] The present invention will be further described in detail below with reference to specific embodiments.

[0055] Example 1

[0056] Weigh out 22.5 kg of ferrous sulfate heptahydrate, 11.8 kg of copper sulfate pentahydrate, and 12.2 kg of cobalt sulfate heptahydrate, dissolve them in deionized water, and add water to make the total solution volume 100 L to obtain a metal ion solution. The concentration of iron ions in the solution is 45 g / L, the concentration of cobalt ions is 25 g / L, and the concentration of copper ions is 30 g / L.

[0057] Weigh 245g of ferric phosphate and add it to the metal ion solution.

[0058] Weigh 20.1 kg of sodium carbonate and add it to deionized water. Add water until the total solution volume is 201 L to obtain a sodium carbonate solution with a sodium carbonate concentration of 100 g / L.

[0059] Both the metal ion solution and the sodium carbonate solution were heated to 60°C. The sodium carbonate solution was slowly added to the metal ion solution while stirring at 100 r / min. After the addition was complete, stirring was continued for 30 minutes until the precipitation reaction was complete.

[0060] The reaction product was filtered and washed repeatedly with water until the chloride ion concentration in the filtrate was less than 50 ppm, thus obtaining a precipitate.

[0061] The precipitate was placed in an oven and dried at 150°C for 6 hours to obtain the precursor.

[0062] The precursor was placed in a hydrogen reduction furnace and reduced at 620°C for 4 hours, with the hydrogen volumetric flux set to 0.03 m / s.

[0063] The reduction product was crushed and sieved to obtain ultrafine pre-alloyed powder.

[0064] In this embodiment, the composition of the ultrafine pre-alloyed powder is: 44.9 wt% iron, 24.7 wt% cobalt, 29.5 wt% copper, 0.5 wt% phosphorus, 0.3 wt% oxygen, with the balance being unavoidable impurities, and its Fisher particle size is 1.4 μm.

[0065] The pre-alloyed powder is loaded into a steel mold with dimensions of 50*10*5mm and cold-pressed under a pressure of 2 tons / square centimeter. The formed blank is then placed in a hydrogen atmosphere sintering furnace and sintered at 900℃ for 60 minutes to obtain a diamond tool sintered body.

[0066] Testing revealed that the diamond sintered body had a density of 98.6%, a Rockwell hardness of HRB106, a flexural strength of 1500 MPa, and an impact toughness of 32 J / cm². 2 .

[0067] Example 2

[0068] Weigh out 21.5 kg of ferrous sulfate heptahydrate, 12.5 kg of copper sulfate pentahydrate, and 12.2 kg of cobalt sulfate heptahydrate, dissolve them in deionized water, and add water to make the total solution volume 100 L to obtain a metal ion solution. The concentration of iron ions in the solution is 43 g / L, the concentration of cobalt ions is 25 g / L, and the concentration of copper ions is 32 g / L.

[0069] Weigh 490g of ferric phosphate and add it to the metal ion solution.

[0070] Weigh 19.55 kg of sodium carbonate and add it to deionized water. Add water until the total solution volume is 195.5 L to obtain a sodium carbonate solution with a sodium carbonate concentration of 100 g / L.

[0071] Both the metal ion solution and the sodium carbonate solution were heated to 50°C. The sodium carbonate solution was slowly added to the metal ion solution while stirring at 120 r / min. After the addition was complete, stirring was continued for 30 minutes until the precipitation reaction was complete.

[0072] The reaction product was filtered and washed repeatedly with water until the chloride ion concentration in the filtrate was less than 50 ppm, thus obtaining a precipitate.

[0073] The precipitate was placed in an oven and dried at 130°C for 8 hours to obtain the precursor.

[0074] The precursor was placed in a hydrogen reduction furnace and reduced at 600°C for 5 hours, with the hydrogen volumetric flux set to 0.03 m / s.

[0075] The reduction product was crushed and sieved to obtain ultrafine pre-alloyed powder.

[0076] In this embodiment, the composition of the ultrafine pre-alloyed powder is: 42.5 wt% iron, 24.5 wt% cobalt, 31.5 wt% copper, 1 wt% phosphorus, 0.4 wt% oxygen, with the balance being unavoidable impurities, and its Fisher particle size is 1.2 μm.

[0077] The pre-alloyed powder is loaded into a steel mold with dimensions of 50*10*5mm and cold-pressed under a pressure of 2 tons / square centimeter. The formed blank is then placed in a hydrogen atmosphere sintering furnace and sintered at 900℃ for 60 minutes to obtain a diamond tool sintered body.

[0078] Testing revealed that the sintered diamond tool body had a density of 99.1%, a Rockwell hardness of HRB110, a flexural strength of 1350 MPa, and an impact toughness of 29 J / cm². 2 .

[0079] Comparative Example 1

[0080] Weigh out 22.96 kg of ferrous sulfate heptahydrate, 11.8 kg of copper sulfate pentahydrate, and 12.2 kg of cobalt sulfate heptahydrate, dissolve them in deionized water, and add water to make the total solution volume 100 L to obtain a metal ion solution. The concentration of iron ions in the solution is 45 g / L, the concentration of cobalt ions is 25 g / L, and the concentration of copper ions is 30 g / L.

[0081] Weigh 103.69g of ferric phosphate and add it to the metal ion solution.

[0082] Weigh 20 kg of sodium carbonate and add it to deionized water. Add water until the total solution volume is 200 L to obtain a sodium carbonate solution with a sodium carbonate concentration of 100 g / L.

[0083] Both the metal ion solution and the sodium carbonate solution were heated to 60°C. The sodium carbonate solution was slowly added to the metal ion solution while stirring at 100 r / min. After the addition was complete, stirring was continued for 30 minutes until the precipitation reaction was complete.

[0084] The reaction product was filtered and washed repeatedly with water until the chloride ion concentration in the filtrate was less than 50 ppm, thus obtaining a precipitate.

[0085] The precipitate was placed in an oven and dried at 150°C for 6 hours to obtain the precursor.

[0086] The precursor was placed in a hydrogen reduction furnace and reduced at 620°C for 4 hours, with the hydrogen volumetric flux set to 0.03 m / s.

[0087] The reduction product was crushed and sieved to obtain ultrafine pre-alloyed powder.

[0088] The composition of the ultrafine pre-alloyed powder in this embodiment is: 45.3 wt% iron, 24.7 wt% cobalt, 29.5 wt% copper, 0.2 wt% phosphorus, 0.2 wt% oxygen, with the balance being unavoidable impurities, and its Fisher particle size is 1.4 μm.

[0089] The pre-alloyed powder is loaded into a steel mold with dimensions of 50*10*5mm and cold-pressed under a pressure of 2 tons / square centimeter. The formed blank is then placed in a hydrogen atmosphere sintering furnace and sintered at 900℃ for 60 minutes to obtain a diamond tool sintered body.

[0090] Testing revealed that the sintered diamond tool body has a density of 92%, a Rockwell hardness of HRB100, a flexural strength of 1235 MPa, and an impact toughness of 25 J / cm². 2 .

[0091] Comparative Example 2

[0092] Weigh out 21.89 kg of ferrous sulfate heptahydrate, 11.8 kg of copper sulfate pentahydrate, and 12.2 kg of cobalt sulfate heptahydrate, dissolve them in deionized water, and add water to make the total solution volume 100 L to obtain a metal ion solution. The concentration of iron ions in the solution is 45 g / L, the concentration of cobalt ions is 25 g / L, and the concentration of copper ions is 30 g / L.

[0093] Weigh 1037g of ferric phosphate and add it to the metal ion solution.

[0094] Weigh 19 kg of sodium carbonate and add it to deionized water. Add water until the total solution volume is 190 L to obtain a sodium carbonate solution with a sodium carbonate concentration of 100 g / L.

[0095] Both the metal ion solution and the sodium carbonate solution were heated to 60°C. The sodium carbonate solution was slowly added to the metal ion solution while stirring at 100 r / min. After the addition was complete, stirring was continued for 30 minutes until the precipitation reaction was complete.

[0096] The reaction product was filtered and washed repeatedly with water until the chloride ion concentration in the filtrate was less than 50 ppm, thus obtaining a precipitate.

[0097] The precipitate was placed in an oven and dried at 150°C for 6 hours to obtain the precursor.

[0098] The precursor was placed in a hydrogen reduction furnace and reduced at 620°C for 4 hours, with the hydrogen volumetric flux set to 0.03 m / s.

[0099] The reduction product was crushed and sieved to obtain ultrafine pre-alloyed powder.

[0100] The composition of the ultrafine pre-alloyed powder in this embodiment is: 43.2 wt% iron, 24.7 wt% cobalt, 29.5 wt% copper, 2 wt% phosphorus, 0.5 wt% oxygen, with the balance being unavoidable impurities, and its Fisher particle size is 1.4 μm.

[0101] The pre-alloyed powder is loaded into a steel mold with dimensions of 50*10*5mm and cold-pressed under a pressure of 2 tons / square centimeter. The formed blank is then placed in a hydrogen atmosphere sintering furnace and sintered at 900℃ for 60 minutes to obtain a diamond tool sintered body.

[0102] Testing revealed that the sintered diamond tool body had a density of 96.1%, a Rockwell hardness of HRB98, a flexural strength of 1074 MPa, and an impact toughness of 5 J / cm². 2 .

[0103] Comparative Example 3

[0104] Weigh out 22.5 kg of ferrous sulfate heptahydrate, 11.8 kg of copper sulfate pentahydrate, and 12.2 kg of cobalt sulfate heptahydrate, dissolve them in deionized water, and add water to make the total solution volume 100 L to obtain a metal ion solution. The concentration of iron ions in the solution is 45 g / L, the concentration of cobalt ions is 25 g / L, and the concentration of copper ions is 30 g / L.

[0105] Weigh 20 kg of sodium carbonate and add it to deionized water. Add water until the total solution volume is 200 L to obtain a sodium carbonate solution with a sodium carbonate concentration of 100 g / L.

[0106] Both the metal ion solution and the sodium carbonate solution were heated to 60°C. The sodium carbonate solution was slowly added to the metal ion solution while stirring at 100 r / min. After the addition was complete, stirring was continued for 30 minutes until the precipitation reaction was complete.

[0107] The reaction product was filtered and washed repeatedly with water until the chloride ion concentration in the filtrate was less than 50 ppm, thus obtaining a precipitate.

[0108] The precipitate was placed in an oven and dried at 150°C for 6 hours. The dried precipitate was then mixed with 245g of ferric phosphate and stirred at 120 rpm for 30 minutes to obtain the precursor.

[0109] The precursor was placed in a hydrogen reduction furnace and reduced at 620°C for 4 hours, with the hydrogen volumetric flux set to 0.03 m / s.

[0110] The reduction product was crushed and sieved to obtain ultrafine pre-alloyed powder.

[0111] In this embodiment, the composition of the ultrafine pre-alloyed powder is: 44.9 wt% iron, 24.7 wt% cobalt, 29.5 wt% copper, 0.5 wt% phosphorus, 0.3 wt% oxygen, with the balance being unavoidable impurities, and its Fisher particle size is 1.4 μm.

[0112] The pre-alloyed powder is loaded into a steel mold with dimensions of 50*10*5mm and cold-pressed under a pressure of 2 tons / square centimeter. The formed blank is then placed in a hydrogen atmosphere sintering furnace and sintered at 900℃ for 60 minutes to obtain a diamond tool sintered body.

[0113] Testing revealed that the sintered diamond tool body had a density of 95.6%, a Rockwell hardness of HRB102, a flexural strength of 1257 MPa, and an impact toughness of 16 J / cm². 2 Analysis suggests that the dried precipitated powder will agglomerate, the particles will become coarser, the uniformity of mechanical mixing will be insufficient, and phosphorus will segregate, resulting in a decrease in product density and toughness.

[0114] Comparative Example 4

[0115] Weigh out 22.5 kg of ferrous sulfate heptahydrate, 11.8 kg of copper sulfate pentahydrate, and 12.2 kg of cobalt sulfate heptahydrate, dissolve them in deionized water, and add water to make the total solution volume 100 L to obtain a metal ion solution. The concentration of iron ions in the solution is 45 g / L, the concentration of cobalt ions is 25 g / L, and the concentration of copper ions is 30 g / L.

[0116] Weigh 20 kg of sodium carbonate and add it to deionized water. Add water until the total solution volume is 200 L to obtain a sodium carbonate solution with a sodium carbonate concentration of 100 g / L.

[0117] Both the metal ion solution and the sodium carbonate solution were heated to 60°C. The sodium carbonate solution was slowly added to the metal ion solution while stirring at 100 r / min. After the addition was complete, stirring was continued for 30 minutes until the precipitation reaction was complete.

[0118] The reaction product was filtered and washed repeatedly with water until the chloride ion concentration in the filtrate was less than 50 ppm, thus obtaining a precipitate.

[0119] The precipitate was placed in an oven and dried at 150°C for 6 hours to obtain the precursor.

[0120] The precursor was placed in a hydrogen reduction furnace and reduced at 620°C for 4 hours, with the hydrogen volumetric flux set to 0.03 m / s.

[0121] The reduction product was crushed and sieved to obtain ultrafine pre-alloyed powder with a Fisher particle size of 1.4 μm.

[0122] The pre-alloyed powder is loaded into a steel mold with dimensions of 50*10*5mm and cold-pressed under a pressure of 2 tons / square centimeter. The formed blank is then placed in a hydrogen atmosphere sintering furnace and sintered at 900℃ for 60 minutes to obtain a diamond tool sintered body.

[0123] Tests showed that the density of the sintered diamond tool reached 92%, the Rockwell hardness was HRB97, and the bending strength was 1069 MPa.

[0124] Comparative Example 5

[0125] The difference between this comparative example and Comparative Example 4 is that the pre-alloyed powder was loaded into a steel mold with dimensions of 50*10*5mm and cold-pressed at a pressure of 2 tons / square centimeter. The formed blank was placed in a hydrogen atmosphere sintering furnace and sintered at 1000℃ for 60 minutes to obtain a diamond tool sintered body.

[0126] Tests showed that the density of the sintered diamond tool reached 95%, the Rockwell hardness was HRB99, and the bending strength was 1214 MPa.

[0127] Comparative Example 6

[0128] The difference between this comparative example and Example 1 is that the ultrafine pre-alloyed powder obtained by crushing and sieving the reduction product has a Fisher particle size of 5 μm. The prepared diamond tool sintered body has a density of 95%, a Rockwell hardness of HRB98, and a flexural strength of 1176 MPa.

[0129] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0130] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing ultrafine pre-alloyed powder, characterized in that, Includes the following steps: A metal ion solution is prepared by dissolving soluble acidic salts of iron, cobalt, and copper in water. A mixed system is prepared by mixing phosphate and metal ion solutions; Heat the mixture to 40℃~60℃, add a weak base, and stir to react and form a precipitate. The precipitate was washed with water and then dried to obtain the precursor. The precursor was reduced to obtain ultrafine pre-alloyed powder; The phosphate is at least one of iron phosphate, cobalt phosphate, and copper phosphate. The ultrafine pre-alloyed powder comprises at least the following components by weight percentage: 30%–50% iron, 20%–30% cobalt, 25%–40% copper, and 0.5%–1% phosphorus.

2. The method for preparing ultrafine pre-alloyed powder according to claim 1, characterized in that, The phosphate has a particle size of 0.5 μm to 2 μm.

3. The method for preparing ultrafine pre-alloyed powder according to claim 1, characterized in that, The weak base is at least one of sodium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium carbonate, and ammonia water.

4. The method for preparing ultrafine pre-alloyed powder according to claim 1, characterized in that, Based on the amount of weak base required for the stoichiometric ratio in the precipitate, when adding a weak base to the mixed system, the amount of weak base added should be 5% to 10% in excess.

5. The method for preparing ultrafine pre-alloyed powder according to claim 1, characterized in that, The total metal ion concentration in the metal ion solution is 60 g / L to 180 g / L.

6. The method for preparing ultrafine pre-alloyed powder according to claim 1, characterized in that, The drying temperature is 120℃~160℃, and the time is 6h~8h.

7. The method for preparing ultrafine pre-alloyed powder according to claim 1, characterized in that, The reduction is carried out in a hydrogen atmosphere at a temperature of 500℃~700℃ for 4h~6h, with a hydrogen volumetric flux of 0.03m / s~0.05m / s.

8. The method for preparing ultrafine pre-alloyed powder according to claim 1, characterized in that, The Fisher particle size of the ultrafine pre-alloyed powder is less than or equal to 2 μm.

9. A diamond sintered body, characterized in that, It is prepared using at least the ultrafine pre-alloyed powder obtained by the preparation method of the ultrafine pre-alloyed powder according to any one of claims 1-8.

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