A method for preparing rare earth-doped WC particle-reinforced iron-based composite materials

Abstract

This invention discloses a method for preparing rare earth-doped WC particle-reinforced iron-based composite materials, belonging to the technical field of wear-resistant and corrosion-resistant composite material preparation. The method involves ball milling rare earth elements with WC particles using paraffin and ethanol, dispersing the rare earth elements onto the surface of the WC particles. After drying in a vacuum environment to remove paraffin and ethanol, the mixture is ball milled again with pure iron powder. The powder is then pressed into discs twice using a tablet press, and sintered in a vacuum sintering furnace at a set temperature. A cyclic heat treatment process of "heating, holding, AC pulse + DC pulse heat treatment" is employed on the preform, followed by cooling to obtain the rare earth-doped WC particle-reinforced iron-based composite material. The rare earth-doped WC particle-reinforced iron-based composite material prepared by this invention exhibits better interfacial metallurgical bonding, reduced porosity defects, and a denser microstructure.

Description

Technical Field

[0001] This invention belongs to the field of wear-resistant and corrosion-resistant composite material preparation technology, specifically relating to a method for preparing rare earth-doped WC particle-reinforced iron-based composite materials. Background Technology

[0002] The interfacial delamination failure of metal-based composite wear-resistant materials poses a threat to wear-resistant parts of in-service machines and causes significant harm to the development of industrial equipment. With the development of modern industry, improving the wear resistance and service life of wear-resistant composite materials should be a major focus. Tungsten carbide particles have high strength, high hardness, good stability, and low cost, and can form a good metallurgical bond with the iron matrix. The traditional preparation process of rare-earth-attached WC particle-reinforced iron-based composite materials typically utilizes a vacuum sintering furnace, setting a suitable temperature for vacuum sintering, resulting in a metallurgical bond at the interface, making the bond tighter. However, samples prepared by a single heat treatment method still exhibit surface porosity, poor density, and unstable interfacial bonding.

[0003] Chinese invention patent application CN108746636A discloses a tungsten carbide steel-based composite material with rare earth-controlled particle micro-interface growth. It uses a mixture of tungsten carbide powder with attached rare earth elements and steel powder as the composite layer, a mixture of tungsten powder and steel powder as the transition layer, and steel powder as the matrix layer. All are pressed together to form a preform, which is then sintered in a vacuum tube furnace. The drawback of this single heat treatment method is that the resulting sample lacks density, leading to easy cracking and insufficient wear resistance during later use. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a method for preparing rare-earth-doped WC particle-reinforced iron-based composite materials. By subjecting the rare-earth-attached WC particle-reinforced iron-based composite material preform to cyclic heat treatment involving heating, heat preservation, and AC pulse + DC pulse, the method aims to refine the grains, improve interfacial bonding strength, and increase the sample density.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0007] (1) WC particles and paraffin are ground and heated in a water bath to obtain WC particles with paraffin attached. Rare earth powder, WC particles with paraffin attached and ethanol are ball-milled to obtain mixture A.

[0008] (2) After drying mixture A, it is mixed with iron powder by ball milling to obtain mixture B, which is then pressed into a preform for cyclic heat treatment. After cyclic heat treatment, it is sintered at 1350℃ for 90 minutes and then cooled to obtain rare earth doped WC particle reinforced iron-based composite material.

[0009] The cyclic heat treatment is performed in the order of sintering, heat preservation, AC pulse, and DC pulse, with a total of 4 cycles. An electric pulse treatment is performed after each sintering heating node to fully utilize the effects of electric pulse treatment on the electroplastic grain refinement, damage repair, and performance recovery of the sample after high-temperature sintering. This results in improved material density, more stable interfacial bonding, grain refinement, and improved and optimized hardness and tensile strength.

[0010] In a preferred embodiment of the present invention, step (2) specifically includes the cyclic heat treatment:

[0011] S1: Heat the preform to 1000℃ for sintering, hold for 10-15 minutes, and then introduce an AC pulse with a frequency of 1-10Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 1~10 Hz, a pulse interval of 50~100 μs, and a pulse current density of 500~1000 A / mm. 2 The total pulse heat treatment time for both DC and AC pulses shall not be less than 10 seconds;

[0012] S2: Heat the preform after S1 heat treatment to 1100℃ for sintering, hold for 10-15 min, and then pass an AC pulse with a pulse frequency of 20-30 Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 20-30 Hz, a pulse interval of 50-100 μs, and a pulse current density of 500-1000 A / mm. 2 The total pulse heat treatment time for both DC and AC pulses shall not be less than 10 seconds;

[0013] S3: Heat the preform after S2 heat treatment to 1200℃ for sintering, hold for 10-15 min, and then introduce an AC pulse with a pulse frequency of 30-40 Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 30–40 Hz, a pulse interval of 50–100 μs, and a pulse current density of 500–1000 A / mm. 2The total pulse heat treatment time for both DC and AC pulses shall not be less than 10 seconds;

[0014] S4: Heat the preform after S3 heat treatment to 1300℃ for sintering, hold for 10-15 min, and then introduce an AC pulse with a pulse frequency of 40-50 Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 40-50 Hz, a pulse interval of 50-100 μs, and a pulse current density of 500-1000 A / mm. 2 The total pulse heat treatment time for both DC and AC is no less than 10 seconds.

[0015] In a preferred embodiment of the present invention, the rare earth powder has a particle size of 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0016] In a preferred embodiment of the present invention, in step (1), the rare earth powder is one of La, Ce, Y and Nd.

[0017] As a preferred embodiment of the present invention, in step (1), the ball milling process is as follows: during ball milling, first rotate forward for 50-60 minutes, then stop for 15-20 minutes, then rotate in reverse for 50-60 minutes, and finally stop for 15-20 minutes, with a rotation speed of 280-300 r / min.

[0018] As a preferred embodiment of the present invention, in step (1), the mass of the rare earth powder is 0.6-1% of the total mass of the rare earth elements and the WC particles attached to the paraffin.

[0019] In a preferred embodiment of the present invention, in step (1), the mass ratio of paraffin wax to WC particles is 1:40.

[0020] In a preferred embodiment of the present invention, in step (2), the mass percentage of iron powder in mixture B is 59-60%.

[0021] In a preferred embodiment of the present invention, in step (2), a vacuum drying oven is used for drying, with a vacuum degree of 6.0 × 10⁻⁶. -1 Pa, dry at 70-75℃ for 5-6 hours, then heat to 200℃ for 11-12 hours.

[0022] As a preferred embodiment of the present invention, in step (2), the pressure is increased to 500-600MPa and held for 3-5 minutes; then the pressure is released and the pressure is increased to 600-700MPa again and held for 8-10 minutes to obtain the preform.

[0023] As a preferred embodiment of the present invention, in step (2), the ball milling process is as follows: first rotate forward for 60-90 minutes, then stop for 10-15 minutes, and then rotate in reverse for 60-90 minutes at 180-200 r / min.

[0024] As a preferred embodiment of the present invention, in step (2), the sintering and cooling process is as follows: from room temperature to 500°C, the rate does not exceed 5°C / min; from 500°C to 800°C, the rate does not exceed 10°C / min; from 800°C to 1000°C, the rate does not exceed 5°C / min; from 1000°C to 1350°C, the rate does not exceed 3°C / min, and the cooling rate is opposite to the heating rate.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] Compared to using a single sintering method, the cyclic heat treatment of rare-earth-attached WC particle-reinforced iron-based composite preforms—combining sintering, heat preservation, and AC pulse + DC pulse heat treatment—allows for vacuum sintering to promote interfacial metallurgical reactions, while pulse treatment induces various phenomena within the sample, such as recrystallization phase transformation, crack healing, and amorphous crystallization. This achieves electroplastic grain refinement, damage repair, and performance recovery. This invention combines cyclic heat treatment and pulse treatment to synergistically regulate the composite material interface, improve sample density, and enhance its mechanical properties. Attached Figure Description

[0027] Figure 1 Metallographic micrographs of rare earth-doped WC particle-reinforced iron-based composite materials prepared in Examples 1-3 and Comparative Example 1, (a) Example 1, (b) Example 2, (c) Example 3, (d) Comparative Example 1.

[0028] Figure 2 The process flow diagram of the cyclic heat treatment and cooling process of the present invention is as follows: (a) is the first cyclic heat treatment; (b) is the second cyclic heat treatment; (c) is the third cyclic heat treatment; (d) is the fourth cyclic heat treatment; and (e) is sintering at 1350°C. Detailed Implementation

[0029] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Example 1

[0030] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0031] (1) Preparation of WC particles with rare earth element dispersion and adhesion treatment: WC particles and paraffin wax are ground and heated in a water bath at a temperature of 60-70℃. The paraffin wax is slowly stirred to adhere to the WC surface. Then, 0.6% rare earth powder Y is added to the ball mill jar containing the paraffin-coated WC particles, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100nm, and the WC particles are spherical cast WC powder with a particle size of 200-250nm.

[0032] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0033] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0034] (3) The obtained rare earth-attached WC particles were ball-milled and mixed with pure iron powder for 2 hours.

[0035] (4) The obtained mixed powder is pressed into a preform by pressing twice with a tablet press.

[0036] (5) The obtained preform is placed in a vacuum tube furnace for sintering. When the sintering temperature reaches 1000℃, it is held for 10 min, and an AC pulse is introduced with a pulse frequency of 1 Hz, a pulse width of 10 μs, a pulse interval of 10 μs, and a pulse current density of 600 A / mm. 2 A DC pulse is applied with a frequency of 10 Hz, a pulse interval of 70 μs, and a pulse current density of 500 A / mm². 2 The total pulse heat treatment time is 18 s.

[0037] (6) The obtained preform is heated to 1100℃ and held for 15 min. An AC pulse is then introduced with a pulse frequency of 25 Hz, a pulse width of 1 μs, a pulse interval of 60 μs, and a pulse current density of 50 A / mm². 2 A DC pulse is applied with a frequency of 25 Hz, a pulse interval of 50 μs, and a pulse current density of 600 A / mm². 2 The total pulse heat treatment time is 10 s.

[0038] (7) The obtained preform is heated to 1200℃ and held for 15 min. An AC pulse is then introduced with a pulse frequency of 40 Hz, a pulse width of 10 μs, a pulse interval of 10 μs, and a pulse current density of 700 A / mm². 2 A DC pulse is applied with a frequency of 40 Hz, a pulse interval of 70 μs, and a pulse current density of 500 A / mm². 2The total pulse heat treatment time is 10 s.

[0039] (8) The obtained preform is heated to 1300℃ and held for 13 min. An AC pulse is then introduced with a pulse frequency of 45 Hz, a pulse width of 10 μs, a pulse interval of 80 μs, and a pulse current density of 50 A / mm². 2 A DC pulse is applied with a frequency of 40 Hz, a pulse interval of 50 μs, and a pulse current density of 1000 A / mm². 2 The total pulse heat treatment time is 10 s.

[0040] (9) The obtained preform is heated to 1350℃, kept at that temperature for 90 minutes and then cooled. Example 2

[0041] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0042] (1) Preparation of rare earth element dispersion and attachment treatment of WC particles: WC particles and paraffin are ground and heated in a water bath. The mixture is slowly stirred to allow the paraffin to adhere to the WC surface. Then, 1% by mass of rare earth powder Nd is added to a ball mill jar containing WC particles with paraffin attachment, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0043] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0044] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0045] (3) The obtained rare earth-attached WC particles are ball-milled and mixed with pure iron powder for 1 hour.

[0046] (4) The obtained mixed powder is pressed into a preform by pressing twice with a tablet press.

[0047] (5) The obtained preform is placed in a vacuum tube furnace for sintering. When the sintering temperature reaches 1000℃, it is held for 15 minutes. An AC pulse is then introduced with a pulse frequency of 10 Hz, a pulse width of 20 μs, a pulse interval of 100 μs, and a pulse current density of 1000 A / mm. 2 A DC pulse is applied with a frequency of 1 Hz, a pulse interval of 100 μs, and a pulse current density of 1000 A / mm. 2 The total pulse heat treatment time is 15 s.

[0048] (6) The obtained preform is heated to 1100℃ and held for 10 min. An AC pulse is then introduced with a pulse frequency of 30 Hz, a pulse width of 20 μs, a pulse interval of 10 μs, and a pulse current density of 1000 A / mm. 2 A DC pulse is applied with a frequency of 20 Hz, a pulse interval of 100 μs, and a pulse current density of 500 A / mm². 2 The total pulse heat treatment time is 12 s.

[0049] (7) The obtained preform is heated to 1200℃ and held for 10 min. An AC pulse is then introduced with a pulse frequency of 30 Hz, a pulse width of 1 μs, a pulse interval of 100 μs, and a pulse current density of 1000 A / mm. 2 A DC pulse is applied with a frequency of 30 Hz, a pulse interval of 50 μs, and a pulse current density of 1000 A / mm². 2 The total pulse heat treatment time is 15 s.

[0050] (8) The obtained preform is heated to 1300℃ and held for 10 min. An AC pulse is then introduced with a pulse frequency of 40 Hz, a pulse width of 20 μs, a pulse interval of 100 μs, and a pulse current density of 1000 A / mm. 2 A DC pulse is applied with a frequency of 50 Hz, a pulse interval of 100 μs, and a pulse current density of 500 A / mm². 2 The total pulse heat treatment time is 15 s.

[0051] (9) The obtained preform is heated to 1350℃, kept at that temperature for 90 minutes and then cooled. Example 3

[0052] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0053] (1) Preparation of rare earth element dispersion and attachment treatment of WC particles: WC particles and paraffin are ground and heated in a water bath. The mixture is slowly stirred to allow the paraffin to adhere to the WC surface. Then, 0.8% by mass of rare earth powder La is added to the ball milling jar containing the paraffin-attached WC particles, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0054] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0055] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0056] (3) The obtained rare earth-attached WC particles are ball-milled and mixed with pure iron powder for 1.5 hours.

[0057] (4) The obtained mixed powder is pressed into a preform by pressing twice with a tablet press.

[0058] (5) The obtained preform is placed in a vacuum tube furnace for sintering. When the sintering temperature reaches 1000℃, it is held for 12 minutes. An AC pulse is then introduced with a pulse frequency of 6 Hz, a pulse width of 1 μs, a pulse interval of 50 μs, and a pulse current density of 50 A / mm². 2 A DC pulse is applied with a frequency of 6 Hz, a pulse interval of 50 μs, and a pulse current density of 800 A / mm². 2 The total pulse heat treatment time is 10 s.

[0059] (6) The obtained preform is heated to 1100℃ and held for 12 min. An AC pulse is then introduced with a pulse frequency of 20 Hz, a pulse width of 10 μs, a pulse interval of 100 μs, and a pulse current density of 500 A / mm². 2 A DC pulse is applied with a frequency of 30 Hz, a pulse interval of 70 μs, and a pulse current density of 1000 A / mm². 2 The total pulse heat treatment time is 20 s.

[0060] (7) The obtained preform is heated to 1200℃ and held for 12 min. An AC pulse is then introduced with a pulse frequency of 35 Hz, a pulse width of 20 μs, a pulse interval of 80 μs, and a pulse current density of 50 A / mm. 2 A DC pulse is applied with a frequency of 35 Hz, a pulse interval of 100 μs, and a pulse current density of 600 A / mm². 2 The total pulse heat treatment time is 12 seconds.

[0061] (8) The obtained preform is heated to 1300℃ and held for 15 min. An AC pulse is then introduced with a pulse frequency of 50 Hz, a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 500 A / mm². 2 A DC pulse is applied with a frequency of 45 Hz, a pulse interval of 50 μs, and a pulse current density of 800 A / mm². 2 The total pulse heat treatment time is 12 s.

[0062] (9) The obtained preform is heated to 1350℃, kept at that temperature for 90 minutes and then cooled.

[0063] Comparative Example 1

[0064] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0065] (1) Preparation of rare earth element dispersion and attachment treatment of WC particles: WC particles and paraffin are ground and heated in a water bath. The mixture is slowly stirred to allow the paraffin to adhere to the WC surface. Then, 0.8% by mass of rare earth powder La is added to the ball milling jar containing the paraffin-attached WC particles, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0066] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0067] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0068] (3) The obtained rare earth-attached WC particles are ball-milled and mixed with pure iron powder for 1.5 hours.

[0069] (4) The obtained mixed powder is pressed into a preform twice using a tablet press;

[0070] (5) The obtained preform is placed in a vacuum tube furnace for sintering. The final sintering temperature is set to 1350℃ and the holding time is 90min before cooling.

[0071] Comparative Example 2

[0072] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0073] (1) Preparation of rare earth element dispersion and attachment treatment of WC particles: WC particles and paraffin are ground and heated in a water bath. The mixture is slowly stirred to allow the paraffin to adhere to the WC surface. Then, 0.8% by mass of rare earth powder La is added to the ball milling jar containing the paraffin-attached WC particles, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0074] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0075] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0076] (3) The obtained rare earth-attached WC particles are ball-milled and mixed with pure iron powder for 1.5 hours.

[0077] (4) The obtained mixed powder is pressed into a preform by pressing twice with a tablet press.

[0078] (5) The obtained preform is placed in a vacuum tube furnace for sintering. When the sintering temperature reaches 1000℃, it is held for 12 minutes; the temperature is raised to 1100℃ and held for 12 minutes; the temperature is raised to 1200℃ and held for 12 minutes; the temperature is raised to 1300℃ and held for 15 minutes; the temperature is raised to 1350℃ and held for 90 minutes before cooling.

[0079] Comparative Example 3

[0080] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0081] (1) Preparation of rare earth element dispersion and attachment treatment of WC particles: WC particles and paraffin are ground and heated in a water bath. The mixture is slowly stirred to allow the paraffin to adhere to the WC surface. Then, 0.8% by mass of rare earth powder La is added to the ball milling jar containing the paraffin-attached WC particles, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0082] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0083] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0084] (3) The obtained rare earth-attached WC particles are ball-milled and mixed with pure iron powder for 1.5 hours.

[0085] (4) The obtained mixed powder is pressed into a preform by pressing twice with a tablet press.

[0086] (5) An AC pulse is passed through the obtained preform with a pulse frequency of 50 Hz, a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 500 A / mm. 2 A DC pulse is applied with a frequency of 45 Hz, a pulse interval of 50 μs, and a pulse current density of 800 A / mm². 2 The total pulse heat treatment time is 44 s.

[0087] Comparative Example 4

[0088] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0089] (1) Preparation of rare earth element dispersion and attachment treatment of WC particles: WC particles and paraffin are ground and heated in a water bath. The mixture is slowly stirred to allow the paraffin to adhere to the WC surface. Then, 0.8% by mass of rare earth powder La is added to the ball milling jar containing the paraffin-attached WC particles, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0090] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0091] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0092] (3) The obtained rare earth-attached WC particles are ball-milled and mixed with pure iron powder for 1.5 hours.

[0093] (4) The obtained mixed powder is pressed into a preform by pressing twice with a tablet press.

[0094] (5) An AC pulse is passed through the obtained preform with a pulse frequency of 6 Hz, a pulse width of 1 μs, a pulse interval of 50 μs, and a pulse current density of 50 A / mm. 2 A DC pulse is applied with a frequency of 6 Hz, a pulse interval of 50 μs, and a pulse current density of 800 A / mm². 2 The total pulse heat treatment time is 10 s.

[0095] (6) Pass an AC pulse into the pre-formed material obtained in step (5), with a pulse frequency of 20 Hz, a pulse width of 10 μs, a pulse interval of 100 μs, and a pulse current density of 500 A / mm. 2 A DC pulse is applied with a frequency of 30 Hz, a pulse interval of 70 μs, and a pulse current density of 1000 A / mm². 2 The total pulse heat treatment time is 20 s.

[0096] (7) Pass the pre-formed AC pulse obtained in step (6) with a pulse frequency of 35 Hz, a pulse width of 20 μs, a pulse interval of 80 μs, and a pulse current density of 50 A / mm. 2A DC pulse is applied with a frequency of 35 Hz, a pulse interval of 100 μs, and a pulse current density of 600 A / mm². 2 The total pulse heat treatment time is 12 seconds.

[0097] (8) Pass the pre-formed AC pulse obtained in step (7) with a pulse frequency of 50 Hz, a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 500 A / mm. 2 A DC pulse is applied with a frequency of 45 Hz, a pulse interval of 50 μs, and a pulse current density of 800 A / mm². 2 The total pulse heat treatment time is 12 s.

[0098] Comparative Example 5

[0099] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0100] (1) Preparation of rare earth element dispersion and attachment treatment of WC particles: WC particles and paraffin are ground and heated in a water bath. The mixture is slowly stirred to allow the paraffin to adhere to the WC surface. Then, 0.8% by mass of rare earth powder La is added to the ball milling jar containing the paraffin-attached WC particles, and ethanol is added for ball milling. The particle size of the rare earth powder is 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

[0101] The ball milling process is as follows: First, rotate clockwise for 60 minutes, then stop for 20 minutes, then rotate counterclockwise for 60 minutes, and finally stop for 20 minutes. The rotation speed is 300 r / min. The above process is repeated 3 times.

[0102] (2) Take out the mixture and put it into a vacuum drying oven to remove ethanol at 70°C and paraffin at 200°C.

[0103] (3) The obtained rare earth-attached WC particles are ball-milled and mixed with pure iron powder for 1.5 hours.

[0104] (4) The obtained mixed powder is pressed into a preform by pressing twice with a tablet press.

[0105] (5) The obtained preform is placed in a vacuum tube furnace for sintering. When the sintering temperature reaches 1000℃, it is held for 12 minutes. An AC pulse is then introduced with a pulse frequency of 6 Hz, a pulse width of 1 μs, a pulse interval of 50 μs, and a pulse current density of 50 A / mm². 2 The pulse heat treatment time is 10 s.

[0106] (6) The obtained preform is heated to 1100℃ and held for 12 min. An AC pulse is then introduced with a pulse frequency of 20 Hz, a pulse width of 10 μs, a pulse interval of 100 μs, and a pulse current density of 500 A / mm². 2 The pulse heat treatment time is 20 s.

[0107] (7) The obtained preform is heated to 1200℃ and held for 12 min. An AC pulse is then introduced with a pulse frequency of 35 Hz, a pulse width of 20 μs, a pulse interval of 80 μs, and a pulse current density of 50 A / mm. 2 The pulse heat treatment time is 12 s.

[0108] (8) The obtained preform is heated to 1300℃ and held for 15 min. An AC pulse is then introduced with a pulse frequency of 50 Hz, a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 500 A / mm². 2 The pulse heat treatment time is 12 s.

[0109] (9) The obtained preform is heated to 1350℃, kept at that temperature for 90 minutes and then cooled.

[0110] Comparative Example 6

[0111] A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material includes the following steps:

[0112] (1) The WC particles and pure iron powder were ball-milled and mixed for 1.5 hours.

[0113] (2) The obtained mixed powder is pressed into a preform by two presses using a tablet press.

[0114] (3) The obtained preform is placed in a vacuum tube furnace for sintering. When the sintering temperature reaches 1000℃, it is held for 12 minutes. An AC pulse is then introduced with a pulse frequency of 6 Hz, a pulse width of 1 μs, a pulse interval of 50 μs, and a pulse current density of 50 A / mm. 2 A DC pulse is applied with a frequency of 6 Hz, a pulse interval of 50 μs, and a pulse current density of 800 A / mm². 2 The total pulse heat treatment time is 10 s.

[0115] (4) The obtained preform is heated to 1100℃ and held for 12 min. An AC pulse is then introduced with a pulse frequency of 20 Hz, a pulse width of 10 μs, a pulse interval of 100 μs, and a pulse current density of 500 A / mm². 2 A DC pulse is applied with a frequency of 30 Hz, a pulse interval of 70 μs, and a pulse current density of 1000 A / mm². 2The total pulse heat treatment time is 20 s.

[0116] (5) The obtained preform is heated to 1200℃ and held for 12 min. An AC pulse is then introduced with a pulse frequency of 35 Hz, a pulse width of 20 μs, a pulse interval of 80 μs, and a pulse current density of 50 A / mm. 2 A DC pulse is applied with a frequency of 35 Hz, a pulse interval of 100 μs, and a pulse current density of 600 A / mm². 2 The total pulse heat treatment time is 12 seconds.

[0117] (6) The obtained preform is heated to 1300℃ and held for 15 min. An AC pulse is then introduced with a pulse frequency of 50 Hz, a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 500 A / mm². 2 A DC pulse is applied with a frequency of 45 Hz, a pulse interval of 50 μs, and a pulse current density of 800 A / mm². 2 The total pulse heat treatment time is 12 s.

[0118] (7) The obtained preform is heated to 1350℃, kept at that temperature for 90 minutes and then cooled.

[0119] The rare earth element-doped WC particle-reinforced iron-based composite materials prepared according to the examples and comparative examples were tested, and the results are shown in Table 1.

[0120] Table 1

[0121] Sample number Interfacial reaction zone hardness (HV) Matrix hardness (HV) Compressive strength (MPa) Example 1 1498 446 598 Example 2 1389 395 463 Example 3 1325 369 659 Comparative Example 1 1211 308 388 Comparative Example 2 1215 305 392 Comparative Example 3 982 212 309 Comparative Example 4 962 204 310 Comparative Example 5 1221 310 351 Comparative Example 6 1102 298 366

[0122] As can be seen from Table 1:

[0123] Compared to Comparative Examples 1-2 and Examples 1-3, it can be seen that Comparative Examples 1-2 did not use the "heating, holding, AC pulse + DC pulse heat treatment" cycle for heat treatment of the preform. The resulting samples had lower hardness and compressive strength, lower hardness in the interface reaction zone, and lower hardness in the matrix. Compared to the samples of Comparative Examples 1-2 with a single sintering method, the samples heat-treated using the "heating, holding, AC pulse + DC pulse heat treatment" cycle exhibit various phenomena such as recrystallization phase transformation, crack healing, and amorphous crystallization within the material, thereby achieving electroplastic grain refinement, damage repair, and performance recovery. This further improves the material's density, strengthens the interfacial bonding, refines the grains, and improves and optimizes hardness and tensile strength. Furthermore, according to... Figure 1 It can be seen that the sample surface of Example 1 has fewer pores, is denser, and has significantly better interfacial bonding.

[0124] Compared to Comparative Examples 3-4 and Example 3, the thermal effect generated by a single electric pulse treatment, compared to the cyclic treatment of "heating, heat preservation, and AC pulse heat treatment," is insufficient to metallurgically bond WC with the iron matrix. The element diffusion rate is reduced, and no interface is formed. Therefore, the bond between the matrix and the WC reinforcement is merely physical, without the formation of an interfacial phase. During material friction and wear service, cracking at the interface is highly likely.

[0125] Compared to Comparative Example 5, Example 3 can more fully utilize the auxiliary effect of electrical pulse treatment. The synergistic effect of AC and DC electrical pulses can promote the movement of solute atoms at different sintering stages, increasing the number of precipitates at grain boundaries, reducing their size, and dispersing their distribution. It also fully leverages the effects of electrical pulse treatment on the electroplastic grain refinement, damage repair, and performance recovery of samples after high-temperature sintering. This results in improved material density, stronger interfacial bonding, refined grains, and improved and optimized hardness and tensile strength.

[0126] Compared with the sample without rare earth elements in Comparative Example 6, 0.6-0.8% of rare earth elements were added in all examples. Due to their low electronegativity, they are more likely to be adsorbed at the grain boundaries of the matrix and reinforcement, and react with the reinforcement phase to generate new substances with low interfacial energy, thereby reducing the interfacial energy, improving the wettability of the matrix and reinforcement, purifying the grain boundaries, and improving the overall strength of the composite material.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a rare earth-doped WC particle-reinforced iron-based composite material, characterized in that, Includes the following steps: (1) WC particles and paraffin are ground and heated in a water bath to obtain WC particles with paraffin attached. Rare earth powder, WC particles with paraffin attached and ethanol are ball-milled to obtain mixture A. (2) After drying mixture A, it is mixed with iron powder by ball milling to obtain mixture B, which is then pressed into a preform for cyclic heat treatment. After cyclic heat treatment, it is sintered at 1350℃ for 90 minutes and cooled to obtain rare earth doped WC particle reinforced iron-based composite material. The cyclic heat treatment specifically includes: S1: Heat the preform to 1000℃ for sintering, hold for 10-15 minutes, and then introduce an AC pulse with a frequency of 1-10 Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 1~10 Hz, a pulse interval of 50~100 μs, and a pulse current density of 500~1000 A / mm. 2 The total pulse heat treatment time shall not be less than 10 s; S2: Heat the preform after S1 heat treatment to 1100℃ for sintering, hold for 10-15 min, and then pass an AC pulse with a pulse frequency of 20-30 Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 20-30 Hz, a pulse interval of 50-100 μs, and a pulse current density of 500-1000 A / mm. 2 The total pulse heat treatment time shall not be less than 10 seconds; S3: Heat the preform after S2 heat treatment to 1200℃ for sintering, hold for 10-15 min, and then introduce an AC pulse with a pulse frequency of 30-40 Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 30-40 Hz, a pulse interval of 50-100 μs, and a pulse current density of 500-1000 A / mm. 2 The total pulse heat treatment time shall not be less than 10 seconds; S4: Heat the preform after S3 heat treatment to 1300℃ for sintering, hold for 10-15 min, and then introduce an AC pulse with a pulse frequency of 40-50 Hz, a pulse width of 1-20 μs, a pulse interval of 10-100 μs, and a pulse current density of 50-1000 A / mm². 2 Then, a DC pulse is applied with a frequency of 40-50 Hz, a pulse interval of 50-100 μs, and a pulse current density of 500-1000 A / mm. 2 The total pulse heat treatment time shall not be less than 10 seconds.

2. The preparation method of the rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, In step (1), the rare earth powder is one of La, Ce, Y, and Nd; the mass of the rare earth powder is 0.6-1% of the total mass of the rare earth powder and the WC particles attached to the paraffin.

3. The preparation method of the rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, The rare earth powder has a particle size of 70-100 nm, and the WC particles are spherical cast WC powder with a particle size of 200-250 nm.

4. The preparation method of the rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, In step (1), the ball milling process is as follows: during ball milling, first rotate forward for 50-60 minutes, then stop for 15-20 minutes, then rotate in reverse for 50-60 minutes, and finally stop for 15-20 minutes, with a rotation speed of 280-300 r / min.

5. The preparation method of the rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, In step (2), a vacuum drying oven is used for drying, with a vacuum degree of 6.0 × 10⁻⁶. -1 Pa, dry at 70-75℃ for 5-6 hours, then heat to 200℃ for 11-12 hours.

6. The preparation method of the rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, In step (2), the pressure is increased to 500-600MPa and held for 3-5 minutes; then the pressure is released and increased to 600-700MPa again and held for 8-10 minutes to obtain the preform.

7. The preparation method of the rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, In step (2), the ball milling process is as follows: first rotate forward for 60-90 minutes, then stop for 10-15 minutes, and then rotate in reverse for 60-90 minutes, with a rotation speed of 180-200 r / min.

8. The method for preparing rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, In step (2), the sintering process is as follows: from room temperature to 500℃, the rate does not exceed 5℃ / min; from 500℃ to 800℃, the rate does not exceed 10℃ / min; from 800℃ to 1000℃, the rate does not exceed 5℃ / min; from 1000℃ to 1350℃, the rate does not exceed 3℃ / min.

9. The preparation method of the rare earth-doped WC particle-reinforced iron-based composite material as described in claim 1, characterized in that, In step (2), the mass percentage of iron powder in mixture B is 59-60%.

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