A method for preparing iron-nickel-tungsten pre-alloyed powder for diamond tool matrix

Abstract

The present invention provides a method for preparing an iron-nickel-tungsten alloy powder, comprising the following steps: 1) batching: 20-70 parts of pure iron, 10-60 parts of electrolytic nickel, 2-30 parts of tungsten powder, and 0-0.3 parts of carbon particles; (2) smelting: adding each raw material in the order of 1 / 2 pure iron → 1 / 2 electrolytic nickel → 1 / 2 tungsten powder → carbon particles → 1 / 2 pure iron → 1 / 2 electrolytic nickel → 1 / 2 tungsten powder; smelting temperature 1300-1700°C, and continuing smelting for 5-10 minutes after reaching the target temperature; (3) atomization; (4) reduction; (5) crushing and screening. The iron-nickel-tungsten pre-alloy powder prepared by the method has uniform composition and low sintering temperature, which avoids the graphitization of diamond particles caused by excessively high sintering temperature, thereby affecting the service life of diamond tools. The obtained sintered matrix has high density, solves the problems of tungsten segregation, excessively high sintering temperature, and high energy consumption, and has a simple preparation process and is easy to operate.

Description

Technical Field

[0001] The invention relates to a method for preparing iron-nickel-tungsten pre-alloyed powder for a diamond tool matrix for a diamond tool, and belongs to the field of abrasive tools. Background Art

[0002] Iron-nickel alloy has been widely used as the basic pre-alloy powder for diamond tools. Adding tungsten powder to iron-nickel alloy can significantly improve the wear resistance and hardness of diamond tools. Traditional iron-nickel-tungsten alloy mainly uses a mechanical mixing method to mix tungsten powder with iron-nickel alloy for sintering. Tungsten-nickel-copper alloy has the low expansion and wear resistance of tungsten. Tungsten can undergo carburization reaction with diamond on the surface of diamond, thereby improving the holding force of the matrix on diamond.

[0003] However, the diamond tools sintered by the traditional mechanical mixing process have the following disadvantages:

[0004] (1) Density of tungsten (19.35 g / cm 3 ) and the density of iron and nickel (the density of iron is 7.86g / cm 3 , the density of nickel is 8.902g / cm 3 ) are quite different, and different powders are prone to uneven mixing during the mixing process, resulting in segregation of tungsten elements;

[0005] (2) Due to the high melting point of tungsten powder, the sintering temperature is above 950°C. When tungsten powder is used as an additive for diamond tools, if the sintering temperature is too high, it will lead to graphitization of diamond particles in the tool, reduce the impact strength, and affect the service life of the tool;

[0006] (3) The sintering temperature of conventional pre-alloyed powder for diamond tools is generally between 750-850℃, which has the advantage of low energy consumption. However, if the mechanically mixed tungsten pre-alloyed powder is sintered according to the conventional low-temperature process, the tungsten element and other alloy elements will not be able to form a metallurgical bond, resulting in a significant decrease in the densification of the diamond tool matrix material. During use, the excellent properties of tungsten powder cannot be fully utilized, affecting the product performance of iron-nickel-tungsten series tools. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing an iron-nickel-tungsten alloy powder. The iron-nickel-tungsten alloy powder prepared by the method has uniform composition, low sintering temperature, high density and good fluidity, thereby solving the problems of segregation and loose product structure in traditional preparation methods.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for preparing iron-nickel-tungsten pre-alloyed powder for diamond tool matrix comprises the following steps:

[0010] (1) Ingredients: Weigh the following raw materials by weight: 20-70 parts of pure iron, 10-60 parts of electrolytic nickel, 2-30 parts of tungsten powder, and 0-0.3 parts of carbon particles;

[0011] (2) Melting:

[0012] Before smelting, nitrogen is continuously charged; then raw materials are added in the order of 1 / 2 pure iron → 1 / 2 electrolytic nickel → 1 / 2 tungsten powder → carbon particles → 1 / 2 pure iron → 1 / 2 electrolytic nickel → 1 / 2 tungsten powder; the smelting temperature is 1300-1700°C, and after reaching the target temperature, smelting is continued for 5-10 minutes to obtain a high-temperature melt;

[0013] (3) Atomization: Atomize the high-temperature molten metal to obtain the iron-nickel-tungsten pre-alloyed mother powder;

[0014] (4) Reduction: After the iron-nickel-tungsten pre-alloyed mother powder is loosened, it passes through a belt reduction furnace and continuously enters the reduction furnace for reduction annealing treatment;

[0015] (5) Crushing and screening:

[0016] The product is obtained after crushing, screening and mixing by using a pulverizer.

[0017] Step (1) Pure iron is in the form of flakes, blocks or powders, with a purity of Fe≥99.9%; electrolytic nickel is in the form of flakes, blocks or powders, with a purity of Ni≥99.9%; the particle size of tungsten powder is -200 mesh, with a purity of W≥99.9%.

[0018] In step (2), the nitrogen flow rate is 40 L / min; the smelting is carried out in a medium frequency smelting furnace; and the smelting temperature is 1500-1600°C.

[0019] The atomization treatment in step (3) is water atomization or gas atomization.

[0020] In step (3), a high-pressure pump is used for atomization, the atomization pressure is 50-100 MPa, the guide tube is Φ3.0-8.0 mm, and the powder particles are crushed into powder particles under the condition of a protective nitrogen flow rate of 40 L / min. The powder particles naturally fall into cooling water for cooling, and then the water-containing powder is collected and vacuum filtered to obtain an iron-nickel-tungsten pre-alloy mother powder with a water content of 1-10 wt%.

[0021] The guide tube is a silicon dioxide guide tube; the content of -170 mesh particle size in the iron-nickel-tungsten pre-alloy mother powder is more than 95%.

[0022] The high-temperature molten liquid passes through the silica guide pipe at the bottom of the tundish to form a liquid column flowing vertically downward, with a pouring speed of 10-20 kg / min. High-pressure water arranged around the liquid column breaks the liquid column into powder particles.

[0023] After the loosening treatment in step (4), the agglomerate diameter of the iron-nickel-tungsten pre-alloyed mother powder is less than 5 cm; and during the screening treatment in step (5), a 300-mesh sieve is used for the treatment.

[0024] In step (4), the reduction temperature is controlled to be 400-1000° C., the reduction belt speed is 5-20 cm / min, the hydrogen is 0-60 L / min, the nitrogen is 0-60 L / min, and the cloth thickness is 5-40 mm; wherein the flow rates of hydrogen and nitrogen are not zero.

[0025] In step (4), the reduction temperature is controlled to be 600-720°C.

[0026] The present invention uses pure iron (which can be in the form of flakes, blocks, or powder), electrolytic nickel (which can be in the form of flakes, blocks, or powder) and tungsten powder as raw materials, and performs smelting and alloying in a medium frequency smelting furnace, and obtains iron-nickel-tungsten pre-alloyed powder after high-pressure atomization, reduction annealing, crushing and screening. The tungsten powder is added in powder form, because the melting point of block tungsten is high (3410°C), it is not easy to melt in the alloy, and it is difficult to form a uniform alloy. The tungsten powder has a small particle size and high activity, and its melting temperature is about 0.6-0.8 times the melting point of the tungsten block. And because of its small particle size, it is easier to achieve the effect of dispersion. The medium frequency furnace used is a power supply device that converts industrial frequency 50HZ alternating current into medium frequency (300HZ or more to 1000HZ). The medium frequency alternating current generates high-density magnetic lines in the induction coil, and cuts the metal material contained in the induction coil, generating a large eddy current in the metal material. The eddy current drives the metal to turn over easily, promoting the diffusion and mass transfer of alloy elements. Forming a homogeneous alloyed metal.

[0027] The iron-nickel-tungsten pre-alloyed powder prepared by the preparation method of the present invention has uniform composition and low sintering temperature (can reach the general sintering temperature of pre-alloyed powder of 750-850°C), avoiding the graphitization of diamond particles caused by excessively high sintering temperature, which affects the service life of diamond tools. The sintered matrix obtained by the present invention has high density, solves the problems of tungsten segregation, excessively high sintering temperature and high energy consumption in traditional preparation methods, and the preparation process is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Process flow chart of iron-nickel-tungsten pre-alloyed powder.

[0029] Figure 2 Scanning electron microscope backscattered photograph of the powder obtained by traditional process (×500).

[0030] Figure 3 A scanning electron microscope backscattered photograph (×500) of the iron-nickel-tungsten alloy powder obtained in the present invention.

[0031] Figure 4Scanning electron microscope surface distribution photograph of the powder obtained by traditional process (×500).

[0032] Figure 5 Scanning electron microscope surface distribution photograph (×500) of the iron-nickel-tungsten alloy powder obtained in the present invention.

[0033] Figure 6 Scanning electron microscope surface distribution photograph of sample 1-1 (×500).

[0034] Figure 7 Scanning electron microscope surface distribution photograph of sample 2-1 (×500). DETAILED DESCRIPTION

[0035] The specific implementation methods of the present invention are further described in detail below in conjunction with the examples. Unless otherwise specified, the instruments and equipment involved in the examples are all conventional instruments and equipment; the raw materials involved are all commercially available conventional raw materials; and the test methods involved are all conventional methods. Example

[0036] A method for preparing iron-nickel-tungsten pre-alloyed powder for diamond tool matrix comprises the following steps:

[0037] (1) Ingredients: Weigh 60 kg of pure iron (purity: Fe ≥ 99.9%), 30 kg of electrolytic nickel block (purity: Ni ≥ 99.9%), 10 kg of tungsten powder (purity: W ≥ 99.9%, particle size: -200 mesh), and 0.3 kg of carbon particles.

[0038] (2) Melting:

[0039] Before smelting begins, nitrogen is continuously filled into the atomizing tube at a nitrogen flow rate of 40L / min to exhaust the air in the atomizing tube;

[0040] Then, in the order of 1 / 2 pure iron (30kg) → 1 / 2 electrolytic nickel (15kg) → 1 / 2 tungsten powder (5kg) → carbon particles (0.3kg) → 1 / 2 pure iron (30kg) → 1 / 2 electrolytic nickel (15kg) → 1 / 2 tungsten powder (5kg), add them into the medium frequency melting furnace for melting and alloying. After reaching the target temperature of 1550℃, continue melting for 5 minutes to obtain a high-temperature melt;

[0041] (3) Atomization:

[0042] The high-temperature molten metal is atomized, the atomization pressure is 70MPa, the silicon dioxide guide tube is Φ6mm, and under the condition of a protective nitrogen flow rate of 40L / min, the high-temperature alloy molten metal passes through the silicon dioxide guide tube at the bottom of the tundish to form a liquid column flowing vertically downward (the pouring speed is 15kg / min), and the high-pressure water set around the liquid column breaks the liquid column into powder particles. The particles naturally fall into the cooling water in the atomization barrel for cooling, and then the water-containing powder is collected by a powder collector and vacuum filtered to obtain an iron-nickel-tungsten pre-alloy mother powder with a water content of about 5wt% (the content of -170 mesh particle size accounts for more than 95%);

[0043] (4) Restore:

[0044] The iron-nickel-tungsten pre-alloyed mother powder with a water content of about 5wt% is loosened (the diameter of the loosened powder agglomerates is less than 5cm), and then passes through a belt reduction furnace. The iron-nickel-tungsten pre-alloyed mother powder continuously enters the reduction furnace for reduction annealing treatment; the reduction temperature is controlled at 650℃, the reduction belt speed is 15cm / min, the hydrogen is 30L / min, the nitrogen is 30L / min, and the cloth thickness is 20mm.

[0045] (5) Crushing and screening

[0046] A universal crusher is used for crushing, and a screening machine with an ultrasonic device is used for sieve separation. The sieve is 300 mesh. The screened material is put into a mixing barrel with a reverse rotating spiral device. After passing the test, it is vacuum packed at 5 kg / bag to obtain an iron-nickel-tungsten pre-alloyed powder product. Example

[0047] A method for preparing iron-nickel-tungsten pre-alloyed powder for diamond tool matrix comprises the following steps:

[0048] (1) Ingredients: Weigh 70 kg of pure iron (purity: Fe ≥ 99.9%), 15 kg of electrolytic nickel (purity: Ni ≥ 99.9%), 15 kg of tungsten powder (purity: W ≥ 99.9%, particle size: -200 mesh), and 0.3 kg of carbon particles.

[0049] (2) Melting:

[0050] Before smelting begins, nitrogen is continuously filled into the atomizing tube at a nitrogen flow rate of 40L / min to exhaust the air in the atomizing tube;

[0051] Then, in the order of 1 / 2 pure iron (35kg) → 1 / 2 electrolytic nickel (7.5kg) → 1 / 2 tungsten powder (7.5kg) → carbon particles (0.3kg) → 1 / 2 pure iron (35kg) → 1 / 2 electrolytic nickel (7.5kg) → 1 / 2 tungsten powder (7.5kg), add them into the medium frequency melting furnace in turn for melting and alloying. After reaching the target temperature of 1600℃, continue melting for 5 minutes to obtain a high-temperature melt;

[0052] (3) Atomization:

[0053] The high-temperature molten metal is atomized, the atomization pressure is 70MPa, the silicon dioxide guide tube is Φ6mm, and under the condition of a protective nitrogen flow rate of 40L / min, the high-temperature alloy molten metal passes through the silicon dioxide guide tube at the bottom of the tundish to form a liquid column flowing vertically downward (the pouring speed is 15kg / min), and the high-pressure water set around the liquid column breaks the liquid column into powder particles. The particles naturally fall into the cooling water in the atomization barrel for cooling, and then the water-containing powder is collected by a powder collector and vacuum filtered to obtain an iron-nickel-tungsten pre-alloy mother powder with a water content of about 5wt% (the content of -170 mesh particle size accounts for more than 95%);

[0054] (4) Restore:

[0055] The iron-nickel-tungsten pre-alloyed mother powder with a water content of about 5wt% is loosened (the diameter of the loosened powder agglomerates is less than 5cm), and then passes through a belt reduction furnace. The iron-nickel-tungsten pre-alloyed mother powder continuously enters the reduction furnace for reduction annealing treatment; the reduction temperature is controlled at 600℃, the reduction belt speed is 13cm / min, the hydrogen is 30L / min, the nitrogen is 30L / min, and the cloth thickness is 20mm.

[0056] (5) Crushing and screening

[0057] A universal crusher is used for crushing, and a screening machine with an ultrasonic device is used for sieve separation. The sieve is 300 mesh. The screened material is put into a mixing barrel with a reverse rotating spiral device. After passing the test, it is vacuum packed at 5 kg / bag to obtain an iron-nickel-tungsten pre-alloyed powder product. Example

[0058] A method for preparing iron-nickel-tungsten pre-alloyed powder for diamond tool matrix comprises the following steps:

[0059] (1) Ingredients: Weigh 20 kg of pure iron (purity: Fe ≥ 99.9%), 60 kg of electrolytic nickel (purity: Ni ≥ 99.9%), and 20 kg of tungsten powder (purity: W ≥ 99.9%, particle size: -200 mesh).

[0060] (2) Melting:

[0061] Before smelting begins, nitrogen is continuously filled into the atomizing tube at a nitrogen flow rate of 40L / min to exhaust the air in the atomizing tube;

[0062] Then, 1 / 2 pure iron (10kg) → 1 / 2 electrolytic nickel (30kg) → 1 / 2 tungsten powder (10kg) → 1 / 2 pure iron (10kg) → 1 / 2 electrolytic nickel (30kg) → 1 / 2 tungsten powder (10kg) are added into the medium frequency melting furnace in the order of melting and alloying. After reaching the target temperature of 1550°C, the melting is continued for 10 minutes to obtain a high-temperature melt.

[0063] (3) Atomization:

[0064] The high-temperature molten metal is atomized, the atomization pressure is 90 MPa, the silicon dioxide guide tube is Φ 8 mm, and under the condition of a protective nitrogen flow rate of 40 L / min, the high-temperature alloy molten metal passes through the silicon dioxide guide tube at the bottom of the tundish to form a liquid column flowing vertically downward (the pouring speed is 20 kg / min), and the high-pressure water set around the liquid column breaks the liquid column into powder particles. The particles naturally fall into the cooling water in the atomization barrel for cooling, and then the water-containing powder is collected by a powder collector and vacuum filtered to obtain an iron-nickel-tungsten pre-alloy mother powder with a water content of about 5wt% (the content of -170 mesh particle size accounts for more than 95%).

[0065] (4) Restore:

[0066] The iron-nickel-tungsten pre-alloyed mother powder with a water content of about 5wt% is loosened (the diameter of the loosened powder agglomerates is less than 5cm), and then passes through a belt reduction furnace. The iron-nickel-tungsten pre-alloyed mother powder continuously enters the reduction furnace for reduction annealing treatment; the reduction temperature is controlled at 700℃, the reduction belt speed is 8 cm / min, the hydrogen is 40 L / min, the nitrogen is 40 L / min, and the cloth thickness is 30 mm.

[0067] (5) Crushing and screening

[0068] A universal crusher is used for crushing, and a screening machine with an ultrasonic device is used for sieve separation. The sieve is 300 mesh. The screened material is put into a mixing barrel with a reverse rotating spiral device. After passing the test, it is vacuum packed at 5 kg / bag to obtain an iron-nickel-tungsten pre-alloyed powder product. Example

[0069] A method for preparing iron-nickel-tungsten pre-alloyed powder for diamond tool matrix comprises the following steps:

[0070] (1) Ingredients: Weigh 50 kg of pure iron (purity: Fe ≥ 99.9%), 30 kg of electrolytic nickel (purity: Ni ≥ 99.9%), 20 kg of tungsten powder (purity: W ≥ 99.9%, particle size: -200 mesh), and 0.1 kg of carbon particles.

[0071] (2) Melting:

[0072] Before smelting begins, nitrogen is continuously filled into the atomizing tube at a nitrogen flow rate of 40L / min to exhaust the air in the atomizing tube;

[0073] Then, in the order of 1 / 2 pure iron (25kg) → 1 / 2 electrolytic nickel (15kg) → 1 / 2 tungsten powder (10kg) → carbon particles (0.1kg) → 1 / 2 pure iron (25kg) → 1 / 2 electrolytic nickel (15kg) → 1 / 2 tungsten powder (10kg), they were added into the medium frequency melting furnace for melting and alloying. After reaching the target temperature of 1550°C, the melting was continued for 5 minutes to obtain a high-temperature melt.

[0074] (3) Atomization:

[0075] The high-temperature molten metal is atomized, the atomization pressure is 80MPa, the silicon dioxide guide tube is Φ 4.5mm, and under the condition of a protective nitrogen flow rate of 40L / min, the high-temperature alloy molten metal passes through the silicon dioxide guide tube at the bottom of the tundish to form a liquid column flowing vertically downward (the pouring speed is 12 kg / min), and the high-pressure water set around the liquid column breaks the liquid column into powder particles, and the particles naturally fall into the cooling water in the atomization barrel for cooling, and then the water-containing powder is collected by a powder collector, and vacuum filtered to obtain an iron-nickel-tungsten pre-alloy mother powder with a water content of about 5wt% (the content of -170 mesh particle size accounts for more than 95%);

[0076] (4) Restore:

[0077] The iron-nickel-tungsten pre-alloyed mother powder with a water content of about 5wt% is loosened (the diameter of the loosened powder agglomerates is less than 5cm), and then passes through a belt reduction furnace. The iron-nickel-tungsten pre-alloyed mother powder continuously enters the reduction furnace for reduction annealing treatment; the reduction temperature is controlled at 720℃, the reduction belt speed is 20 cm / min, the hydrogen is 40 L / min, the nitrogen is 40 L / min, and the cloth thickness is 15 mm.

[0078] (5) Crushing and screening

[0079] A universal crusher is used for crushing, and a screening machine with an ultrasonic device is used for sieve separation. The sieve is 300 mesh. The screened material is put into a mixing barrel with a reverse rotating spiral device. After passing the test, it is vacuum packed at 5 kg / bag to obtain an iron-nickel-tungsten pre-alloyed powder product.

[0080] According to the conventional method, the iron-nickel pre-alloyed powder and the tungsten powder are mixed in a mixer to obtain a mechanically mixed iron-nickel-tungsten powder.

[0081] The iron-nickel-tungsten pre-alloyed powders obtained in Examples 1-4 of the present invention have uniform composition and high sintered matrix density. Taking the iron-nickel-tungsten pre-alloyed powder obtained in Example 1 as an example, its performance is analyzed and measured.

[0082] 1. In order to detect the distribution state of tungsten alloy in alloy powder, a Japanese JSM-6380LA scanning electron microscope was used to perform backscattering analysis, such as Figure 2 and Figure 3 As shown, the element surface distribution photos are as follows Figure 4 and Figure 5 shown.

[0083] Figure 2 and Figure 4 The iron-nickel-tungsten alloy powder produced by the traditional method (mechanical mixing, comparative example 1) is Figure 3 and Figure 5 The iron-nickel-tungsten alloy powder produced by the process used in the present invention (Example 1) is Figure 2 The dark gray part is iron-nickel pre-alloyed powder, and the white part is tungsten powder. Figure 4 The scanning electron microscope distribution photo of tungsten element in the powder corresponds to that in the iron-nickel-tungsten alloy powder produced by the traditional method. Figure 3 No individual tungsten particles were found in the backscattered images. Figure 5 The scanning electron microscope distribution photo of tungsten element in the powder corresponds to that in the powder, indicating that there is no agglomeration of tungsten powder in the iron-nickel-tungsten alloy powder produced by the process method of the present invention.

[0084] 2. In order to further detect the distribution state of elements in the two powder sintered bodies and the performance of the powder sintered bodies, the following sample preparation and testing were carried out.

[0085] (1) Sample preparation process: Weigh two powders of the same weight (respectively: Comparative Example 1: powder obtained by mechanically mixing iron-nickel alloy powder and tungsten powder; Example 1: iron-nickel-tungsten alloy powder obtained by the process of the present invention), and use the same process (sintering temperature 850°C) to sinter into metal samples with a size of 40 mm × 8 mm × 3.2 mm.

[0086] The iron-nickel-tungsten powder obtained by mechanical mixing (comparative example 1) was sintered as sample 1, which was repeated four times and the four samples were marked as 1-1, 1-2, 1-3 and 1-4 respectively; the iron-nickel-tungsten alloy powder prepared by the process of the present invention (example 1) was sintered as sample 2, which was repeated four times and the four samples were marked as 2-1, 2-2, 2-3 and 2-4 respectively.

[0087] (2) Element distribution uniformity test: To determine the uniformity of tungsten elements in the two powder sintered bodies,

[0088] Samples 1-1 and 2-1 were selected and cross-sectional distribution scanning analysis was performed using a Japanese JSM-6380LA scanning electron microscope. Figure 6 and Figure 7 It can be seen that the distribution of iron and nickel in sample 1-1 is relatively uniform, but the distribution of tungsten is in two forms: aggregation and dispersion. Figure 6 The white dots in the tungsten image are scanned images formed by the aggregation of tungsten powder; Figure 7 The iron, nickel and tungsten of sample 2-1 are evenly distributed, because there are no aggregated white spots in the tungsten image, which shows that the iron-nickel-tungsten pre-alloy powder prepared by the present invention has good uniformity.

[0089] 3. Testing of strength, hardness, density and other indicators:

[0090] The eight sintered samples were tested for hardness using a Rockwell hardness tester from Laizhou Dechuan Testing Instrument Co., Ltd., and each sample was tested 4 times. The three-point bending strength of the samples was tested using a universal material testing machine GP-TS2000L from Shenzhen Gaopin Testing Equipment Co., Ltd., China. The density was tested using the Archimedes principle, and each sample was tested 3 times to take the average value, as shown in Table 1.

[0091] Table 1 Sintered matrix performance test

[0092] Hardness comparison: From Table 1, it can be seen that the hardness of sample 2 is 75-77, and the hardness of sample 1 is 68-77. The fluctuation range of sample 2 is smaller than that of sample 1. The main reason is that the tungsten powder in sample 1 is dispersed around the iron and nickel elements in the form of a single substance, and there is agglomeration. When the hardness tester hits this point, the hardness fluctuation is relatively large.

[0093] Strength comparison: The strength of sample 2 is about 40MPa higher than that of sample 1 on average. This is mainly due to the high sintering temperature required for the sintering of the tungsten powder and the iron-nickel mixed powder in sample 1. Under the sintering temperature of 850℃, the metallurgical bonding force is weak. The tungsten element in sample 2 is evenly distributed in the iron-nickel lattice through the smelting process, which has the effect of solid solution strengthening and improves the overall strength of the material.

[0094] Density comparison: The average density of the four samples of sample 1 is 91.24%, 91.24%, 91.30% and 91.20%; the average density of the four samples of sample 2 is 94.55%, 94.59%, 94.59% and 94.56%. By comparison, the density of sample 2 is about 3.3% higher than that of sample 1, and the density is higher.

Claims

1. A method for preparing iron-nickel-tungsten prealloyed powder for diamond tool matrix, characterized in that: The following steps are involved: (1) Ingredients: Weigh the following raw materials by weight: 20-70 parts of pure iron, 10-60 parts of electrolytic nickel, 2-30 parts of tungsten powder, and 0-0.3 parts of carbon particles; Among them, pure iron is in the form of flakes, blocks or powders, with a purity of Fe≥99.9%; electrolytic nickel is in the form of flakes, blocks or powders, with a purity of Ni≥99.9%; the particle size of tungsten powder is -200 mesh, with a purity of W≥99.9%; (2) Melting: Before smelting, nitrogen is continuously charged; then raw materials are added in the order of 1 / 2 pure iron → 1 / 2 electrolytic nickel → 1 / 2 tungsten powder → carbon particles → 1 / 2 pure iron → 1 / 2 electrolytic nickel → 1 / 2 tungsten powder; the smelting temperature is 1300-1700°C, and after reaching the target temperature, smelting is continued for 5-10 minutes to obtain a high-temperature melt; (3) Atomization: Atomize the high-temperature molten metal to obtain the iron-nickel-tungsten pre-alloyed mother powder; (4) Reduction: After the iron-nickel-tungsten pre-alloyed mother powder is loosened, it passes through a belt reduction furnace and continuously enters the reduction furnace for reduction annealing treatment; (5) Crushing and screening: The product is obtained after crushing, screening and mixing by using a pulverizer.

2. The preparation method according to claim 1, characterized in that In step (2), the nitrogen flow rate is 40 L / min; the smelting is carried out in a medium frequency smelting furnace; and the smelting temperature is 1500-1600°C.

3. The preparation method according to claim 1, characterized in that: The atomization treatment in step (3) is water atomization or gas atomization.

4. The preparation method according to claim 1, characterized in that: In step (3), a high-pressure pump is used for atomization, the atomization pressure is 50-100 MPa, the guide tube is Φ3.0-8.0 mm, and the powder particles are crushed into powder particles under the condition of a protective nitrogen flow rate of 40 L / min. The powder particles naturally fall into cooling water for cooling, and then the water-containing powder is collected and vacuum filtered to obtain an iron-nickel-tungsten pre-alloy mother powder with a water content of 1-10 wt%.

5. The preparation method according to claim 4, characterized in that: The guide tube is a silicon dioxide guide tube; the content of -170 mesh particle size in the iron-nickel-tungsten pre-alloy mother powder is more than 95%.

6. The preparation method according to claim 4, characterized in that: The high-temperature molten liquid passes through the silica guide pipe at the bottom of the tundish to form a liquid column flowing vertically downward, with a pouring speed of 10-20 kg / min. High-pressure water arranged around the liquid column breaks the liquid column into powder particles.

7. The preparation method according to claim 1, characterized in that: After the loosening treatment in step (4), the agglomerate diameter of the iron-nickel-tungsten pre-alloyed mother powder is less than 5 cm; and during the screening treatment in step (5), a 300-mesh sieve is used for the treatment.

8. The preparation method according to claim 1, characterized in that: In step (4), the reduction temperature is controlled to be 400-1000° C., the reduction belt speed is 5-20 cm / min, the hydrogen is 0-60 L / min, the nitrogen is 0-60 L / min, and the cloth thickness is 5-40 mm; wherein the flow rates of hydrogen and nitrogen are not zero.

9. The preparation method according to claim 8, characterized in that: In step (4), the reduction temperature is controlled to be 600-720°C.

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