A sintered nickel-based alloy with high wear resistance and its preparation method

Abstract

The present invention relates to a sintered nickel-based alloy with high wear resistance and its preparation process. The preparation uses nickel powder as the main powder and adds various alloy powders and pure element powders. Among them, the mass percentage of B4C powder as the strengthening powder is 2.54 - 7.63%, and the mass percentage of Fe-72%Si powder is 2.78 - 8.33%. In the present invention, the preparation process of the sintered nickel-based alloy mainly includes powder mixing of various powders, powder forming of the mixed powder, and segmented sintering of the green body under atmosphere protection. At a relatively low sintering temperature of 1025°C - 1075°C, high-density densification is achieved by partial liquid-phase sintering, and the dimensional stability of the sintered specimen is maintained. The sintered nickel-based alloy prepared by the present invention has hard phases M7(B,C)3 and M 23 (B,C)6 uniformly distributed in the nickel matrix, with a relative density of 95.38% - 98.62%, a hardness of 56.1 - 60.9 HRC. If the wear resistance of 42CrMo quenched and tempered steel is defined as 1, its relative wear resistance is 2.98 - 4.31, having high density, high hardness, and high wear resistance.

Description

Technical Field

[0001] The present invention belongs to the field of nickel-based alloys, and relates to a sintered nickel-based alloy with high hardness and high wear resistance and a preparation method thereof. Technical Background

[0002] Nickel-based alloys are alloys with various advantages such as high hardness, high strength, and high corrosion resistance. They are usually formed by adding alloying elements such as chromium, molybdenum, and iron to nickel. Generally speaking, the hardness of nickel-based alloys is between 30 and 40 HRC, and a few nickel-based alloys can reach 50 HRC. This high-hardness feature enables them to still possess excellent friction and wear performance in relatively extreme environments such as high temperature and high pressure. Therefore, nickel-based alloys are widely used in fields such as aerospace, petrochemical industry, nuclear industry, household appliances, etc. For example, in the aerospace field, nickel-based alloys are often used to prepare high-temperature and high-pressure turbine blades, combustion chambers, etc. Their high hardness and high wear resistance characteristics make them widely used in the industrial field. In addition, the excellent high-temperature strength, corrosion resistance, oxidation resistance, etc. of nickel-based alloys make them increasingly become an indispensable application material for the manufacture of various high-end industrial equipment.

[0003] For currently prepared sintered nickel-based alloys, the hardness rarely exceeds 50 HRC. The limitation of the hardness level hinders the improvement of their wear resistance, thus restricting their further application in various fields. Therefore, it is very important to explore some strengthening substances and regulate their addition amounts to improve the hardness and wear resistance of nickel-based alloys. B4C has extremely high hardness and wear resistance, while Fe-72% Si has the characteristics of deoxidation and improving wear resistance. Therefore, using B4C and Fe-72% Si as strengthening substances can greatly improve the hardness and wear resistance of nickel-based alloys. Powder metallurgy technology can directly obtain parts and components with complex shapes through powder mixing, pressing, and sintering, reducing high machining costs. Using Ni powder as the matrix powder and adding a certain content of B4C powder, Fe-72% Si powder, Cr powder, etc., and sintering and forming through powder metallurgy, it is expected to obtain high-wear-resistant nickel-based alloy parts and components, which has very important application prospects. Summary of the Invention

[0004] The present invention aims to provide a sintered nickel-based alloy with high wear resistance and a preparation method thereof by regulating the powder ratios of Ni, Cu, Mo, B4C, Fe-72% Si, Cr, etc. and the sintering heating process.

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

[0006] The mass percentages of the raw material powders used for the sintered nickel-based alloy are as follows: B4C: 2.54% to 7.63%; Fe-72% Si: 2.78% to 8.33%; Cr: 16% to 25%; Ni, Cu, and Mo: 64.35% to 79.35%; among which the mass ratio of Ni, Cu, and Mo is: 11:1:1; after the powders are mixed, formed, and sintered, the relative density is 95.38% to 98.62%, and the hardness is 56.1 to 60.9 HRC; taking the wear resistance of 42CrMo quenched and tempered steel as 1, the relative wear resistance of the sintered nickel-based alloy is 2.98 to 4.31; this sintered nickel-based alloy has the characteristics of high density, high hardness, and high wear resistance.

[0007] The preparation method of the sintered nickel-based alloy with the above high wear resistance includes the following steps:

[0008] (1) Powder mixing: Prepare B4C powder, Fe-72% Si powder, Cr powder, Ni powder, Cu powder, and Mo powder according to the required proportions; weigh the powders and then mix them; after mixing the powders, perform drying and sieving; the means of powder mixing include planetary ball milling mixing, vibration ball milling mixing, V-type mixing, and drum mixing.

[0009] (2) Powder forming: Cold press the dried powders using a mold, or use cold isostatic pressing to obtain a green compact with a certain strength and density; the pressing pressure for cold pressing with a mold is 400 MPa to 600 MPa, and the holding pressure for cold isostatic pressing is 200 MPa to 300 MPa.

[0010] (3) Sintering: Transfer the green compact after powder forming into a sintering furnace that can pass a protective atmosphere, and perform sintering under the protective atmosphere to obtain a sintered nickel-based alloy; a segmented heating program is adopted during sintering, and the heating and sintering are completed under the protection of an argon, nitrogen, or argon + hydrogen mixed atmosphere; the segmented heating program is as follows: Heat the green body from room temperature to 200 °C at a heating rate of 1 °C / min to 2 °C / min, and then hold for 0.5 h to 1 h; then heat to 400 °C at a heating rate of 4 °C / min to 7 °C / min, and hold for 0.5 h to 1 h; then heat to 800 °C at a heating rate of 5 °C / min to 8 °C / min, and hold for 0.5 h to 1 h; then heat to 950 °C at a heating rate of 4 °C / min to 6 °C / min, and hold for 1 h to 1.5 h; then heat to 1025 °C to 1075 °C at a heating rate of 5 °C / min to 7 °C / min, and hold for 1.5 h to 2 h; this segmented heating program is set based on the physical and chemical reaction process of the powder green compact; after sintering is completed, cool to room temperature with the furnace; take out the sintered sample to obtain the sintered nickel-based alloy.

[0011] For the above three steps of preparing the sintered nickel-based alloy, taking the preparation of 100 g of nickel-based powder as an example, the details are as follows:

[0012] Step (1): The specific steps for preparing 100 g of nickel-based powder are as follows:

[0013] Preliminary mixing: Put 2.54 g - 7.63 g of boron carbide (B4C) powder, 2.78 g - 8.33 g of iron-silicon (Fe-72% Si) powder, 10 g - 25 g of chromium (Cr) powder, 54.45 g - 67.15 g of nickel (Ni) powder, 4.95 g - 6.10 g of molybdenum (Mo) powder, and 4.95 g - 6.10 g of copper (Cu) powder into a container, and conduct preliminary stirring and grinding for 20 min;

[0014] Powder mixing: For ball milling and mixing, add the preliminarily mixed powder into a ball milling tank, add ball milling balls according to a ball-to-material ratio of 0.8 - 1.2, and add absolute ethanol according to a ratio of 20 - 30 ml / 100 g of powder; first, conduct preliminary stirring and mixing of the powder, ball milling balls, and absolute ethanol for 5 min, and then place the ball milling tank in a ball mill to start ball milling; the revolution speed of the planetary ball mill for mixing is 200 - 300 r / min, rotating clockwise and counterclockwise alternately, and the single-direction rotation time is 30 min; or the swing vibration frequency of the vibration ball mill for mixing is 400 - 500 times / min, the amplitude of the tank body in the up-and-down direction is 30 - 40 mm, and the amplitude of the tank body in the front-back and left-right directions is 10 - 15 mm; after ball milling and mixing for 18 - 20 h, open the lid of the ball milling tank and place it in a vacuum drying oven for drying for 8 - 10 h, and then pass the dried powder through a sieve to separate the powder and ball milling balls to obtain a uniformly mixed and well-formable mixed powder; or add the preliminarily mixed powder into a roller or V-shaped barrel, set the rotation speed to 18 - 20 r / min, and the mixing time to 20 - 24 h; take out the powder after mixing; place the powder in a vacuum drying oven for drying for 7 - 8 h, and pass the dried powder through a sieve to obtain a uniformly mixed and well-formable mixed powder.

[0015] Step (2): Using the mixed powder obtained in step (1), the specific steps for preparing a green compact with a certain strength and density are as follows:

[0016] Weigh the mixed powder with an electronic balance and fill it into a cold pressing die; the cold pressing pressure is 400 - 600 MPa, and the pressure holding time is 15 - 25 s to obtain a powder-formed green compact; among them, the cold pressing die includes a carbon steel die, an alloy steel die, a stainless steel die, or a cemented carbide die;

[0017] Alternatively, by means of cold isostatic pressing, weigh the mixed powder with an electronic balance, fill the powder into a cold isostatic pressing sleeve made of rubber or plastic, and use a cold isostatic pressing pressure of 200-300 MPa for molding. The pressure holding time is 50-60 minutes to obtain a powder molded green compact.

[0018] Step (3): The specific steps for carrying out atmosphere protection sintering on the green compact to obtain a sintered nickel-based alloy are as follows:

[0019] Put the green compact into a firing boat and place it together in a sintering furnace capable of passing a protective atmosphere. After filling with a protective gas, start sintering; wherein the firing boat includes alumina, zirconia, and magnesia firing boats; the protective atmosphere includes argon, nitrogen, and a mixed gas of argon + 5 vol% - 10 vol% hydrogen; then complete the sintering according to the segmented heating program described in step (3).

[0020] During the above atmosphere sintering process, multi-stage slow heating is adopted to remove moisture and oxygen in the green compact. Under the sintering conditions at a relatively low sintering temperature, the sintering densification of the sample is better achieved, and the size stability of the sample is maintained. Compared with the existing sintered nickel-based alloys, the sintered nickel-based alloy prepared by the present invention has the following advantages:

[0021] (1) This sintered nickel-based alloy involves solid-phase sintering and partial liquid-phase sintering at a temperature of 1025-1075 °C, achieving a relatively high degree of densification of 95.38% - 98.62% at a relatively low sintering temperature, while maintaining the size stability of the sintered product, without significant shrinkage or deformation.

[0022] (2) In this sintered nickel-based alloy, the hard phases M7(B,C)3 and M 23 (B,C)6 are evenly distributed in the nickel matrix, playing a strengthening role and improving the hardness and wear resistance of the sintered nickel-based alloy.

[0023] (3) The hardness of this sintered nickel-based alloy reaches a relatively high level of 56.1 - 60.9 HRC. If the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of the sintered nickel-based alloy prepared by the present invention reaches 2.98 - 4.31, featuring high hardness and high wear resistance.

[0024] (4) The sintered nickel-based alloy produced by the present invention has the advantages of simple process flow, simple equipment, and low cost. Description of the Drawings

[0025] Figure 1 XRD diffraction pattern of the sintered nickel-based alloy prepared in Example 1

[0026] Figure 2 Metallographic photo of the sintered nickel-based alloy prepared in Example 1

[0027] Figure 3 Friction Coefficient Curves of Sintered Nickel-based Alloys and 42CrMo Quenched and Tempered Steels Prepared in Examples 1-6 Detailed Implementation Modes

[0028] Example 1

[0029] 1. Powder mixing: Weigh 5.09% B4C powder, 5.56% Fe-72% Si powder, 16% Cr powder, 62.07% Ni powder, 5.64% Cu powder, and 5.64% Mo powder according to the mass ratio and add them to a mortar for 20 minutes of preliminary stirring and grinding; then add the preliminarily mixed powder to a ball milling tank, add cemented carbide balls according to a ball-to-material ratio of 1.2:1, and add absolute ethanol according to a ratio of 25 ml / 100 g of powder; first, conduct 5 minutes of preliminary stirring and mixing of the powder, ball milling balls, and absolute ethanol, and then place the ball milling tank in a planetary ball mill to start ball milling; the rotation speed is 200 r / min, rotating clockwise and counterclockwise alternately, and the single-direction rotation time is 30 minutes; after ball milling for 18 hours, open the lid of the ball milling tank and place it in a vacuum drying oven for 8 hours of drying, and then pass the dried powder through an 80-mesh sieve to separate the powder and ball milling balls, obtaining a powder with uniform mixing and good formability.

[0030] 2. Powder forming: Weigh 7 g of the mixed powder with an electronic balance and fill it into a carbon steel mold, adopting an up-and-down two-way pressing method; the pressing pressure is 550 MPa, and the pressure holding time is 20 seconds; after demolding, a cuboid green compact with a length of 25.1 mm, a width of 8.1 mm, and a height of 4.2 mm with certain strength and density is obtained.

[0031] 3. Sintering: Place the green compact in an alumina boat and put it into an atmosphere tube furnace together. After filling with argon at normal pressure, start sintering; heat the green compact from room temperature to 200 °C at a heating rate of 1 °C / min and hold for 1 h; then heat it to 400 °C at a heating rate of 5 °C / min and hold for 0.5 h; then heat it to 800 °C at a heating rate of 7 °C / min and hold for 1 h; then heat it to 950 °C at a heating rate of 4 °C / min and hold for 1.5 h; then heat it to 1075 °C at a heating rate of 6 °C / min and hold for 1.5 h; cool it to room temperature with the furnace; take out the sintered sample to obtain a sintered nickel-based alloy.

[0032] The composition phases of the sintered nickel-based alloy prepared by the above method are: γ-Ni, Ni3B, M7(B,C)3, M 23 (B,C)6. Figure 1 is the XRD diffraction pattern of the sintered alloy, indicating that the sintered nickel-based alloy is composed of the above phases. In this sintered nickel-based alloy, the hard phases M7(B,C)3, M 23(B,C)6 is evenly distributed in the nickel matrix. Figure 2 This is the metallographic photo of the sintered alloy. It can be seen from Figure 2 it that the phase M7(B,C)3 shown as white blocks, and the phase M shown as black dendritic 23 (B,C)6. And M7(B,C)3 and M 23 (B,C)6 are evenly distributed in the nickel matrix, where M 23 (B,C)6 is mostly distributed around M7(B,C)3. The relative density of this sintered alloy reaches 98.62%, and the hardness is 60.3 HRC. Figure 3 This shows the friction coefficient curve of this sintered alloy. Its average friction coefficient is 0.189, while the average friction coefficient of 42CrMo quenched and tempered steel is 0.670. The average friction coefficient of this sintered alloy is 0.481 lower than that of 42CrMo quenched and tempered steel. Through the calculation of volume wear rate, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this sintered nickel-based alloy reaches 4.31, featuring high hardness and high wear resistance.

[0033] Example 2

[0034] 1. Powder mixing: Weigh 7.63% B4C powder, 8.33% Fe-72% Si powder, 16% Cr powder, 57.58% Ni powder, 5.23% Cu, and 5.23% Mo powder according to the mass ratio and add them into a mortar for 20 minutes of preliminary stirring and grinding. Then add the preliminarily mixed powder into a ball mill tank, add stainless steel balls according to the ball-to-material ratio of 0.8:1, and add absolute ethanol according to the ratio of 20 ml / 100 g powder. First, conduct 5 minutes of preliminary stirring and mixing of the powder, ball mill balls, and absolute ethanol, and then place the ball mill tank in a vibration ball mill to start ball milling. The swing frequency of the vibration mixer is 400 times / min, the amplitude of the tank body in the up and down direction is 40 mm, and the amplitude of the tank body in the front and back, left and right directions is 15 mm. After ball milling for 20 h, open the lid of the ball mill tank and place it in a vacuum drying oven for 8 h of drying. Then pass the dried powder through an 80-mesh sieve to separate the powder and ball mill balls, obtaining powder with good uniformity and formability.

[0035] 2. Powder forming: Weigh 25 g of the mixed powder with an electronic balance, fill it into a rubber sleeve, and place it in a sealed bag for vacuum sealing treatment. Use a pressure of 200 MPa in a cold isostatic press to hold the pressure for 60 minutes to obtain a cylindrical green compact with a diameter of Φ20 mm and a height of 7.9 mm, having a certain density and strength.

[0036] 3. Sintering: Place the green compact into a zirconia boat and then put it into an atmosphere tube furnace. After filling with argon at atmospheric pressure, start sintering. Heat the green compact from room temperature to 200 °C at a heating rate of 1 °C / min, and then hold for 1 h. Then heat it to 400 °C at a heating rate of 4 °C / min and hold for 1 h. Next, heat it to 800 °C at a heating rate of 7 °C / min and hold for 0.5 h. Then heat it to 950 °C at a heating rate of 4 °C / min and hold for 1 h. Then heat it to 1025 °C at a heating rate of 7 °C / min and hold for 2 h. Cool it to room temperature in the furnace. Take out the sintered sample to obtain the sintered nickel-based alloy.

[0037] The composition phases of the sintered nickel-based alloy prepared by the above method are: γ-Ni, Ni3B, M7(B,C)3, M 23 (B,C)6. The hard phases M7(B,C)3 and M 23 (B,C)6 are uniformly distributed in the nickel matrix, and the hard phase M7(B,C)3 has a larger volume. The relative density of this sintered alloy reaches 97.01%, and the hardness is 59.7 HRC. Figure 3 The friction coefficient curve of this sintered alloy is shown in [reference]. Its average friction coefficient is 0.498, while the average friction coefficient of 42CrMo quenched and tempered steel is 0.670. The average friction coefficient of this sintered alloy is 0.172 lower than that of 42CrMo quenched and tempered steel. After calculating the volume wear rate, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this sintered nickel-based alloy reaches 3.65, featuring high hardness and high wear resistance.

[0038] Example 3

[0039] 1. Powder mixing: Weigh 2.54% B4C powder, 2.78% Fe-72% Si powder, 16% Cr powder, 66.58% Ni powder, 6.05% Cu, and 6.05% Mo powder according to the mass ratio and add them to a mortar for 20 min of preliminary stirring and grinding. Add the preliminarily mixed powder to a V-shaped barrel, set the rotation speed to 20 r / min, and the mixing time to 20 h. After mixing, align the outlet of the mixer with the ground and take out the mixed powder. Place the powder in a vacuum drying oven for 7 h, and then pass the dried powder through an 80-mesh sieve to obtain uniformly mixed powder with good formability.

[0040] 2. Powder forming: Weigh 6 g of the mixed powder with an electronic balance and fill it into an alloy steel mold, using the up-and-down two-way pressing method. The pressing pressure is 600 MPa, and the pressure holding time is 25 s. After demolding, a cuboid green compact with a length of 24.7 mm, a width of 7.8 mm, and a height of 4.0 mm with certain strength and density is obtained.

[0041] 3. Sintering: Place the green compact into a zirconia boat and then put it into an atmosphere box furnace. After filling with nitrogen at normal pressure, start sintering. Heat the green compact from room temperature to 200 °C at a heating rate of 2 °C / min and then hold for 0.5 h; then heat it to 400 °C at a heating rate of 7 °C / min and hold for another 0.5 h; then heat it to 800 °C at a heating rate of 8 °C / min and hold for 1 h; then heat it to 950 °C at a heating rate of 6 °C / min and hold for 1 h; then heat it to 1050 °C at a heating rate of 7 °C / min and hold for 2 h; cool it to room temperature in the furnace; take out the sintered sample to obtain the sintered nickel-based alloy.

[0042] The composition phases of the sintered nickel-based alloy prepared by the above method are: γ-Ni, Ni3B, M7(B,C)3, M 23 (B,C)6. The hard phases M7(B,C)3 and M 23 (B,C)6 are evenly distributed in the nickel matrix, and the hard phase M7(B,C)3 is relatively less and more dispersed. The relative density of the sintered alloy is 96.94%, and the hardness is 56.1 HRC. Figure 3 The friction coefficient curve of the sintered alloy is shown in [reference]. Its average friction coefficient is 0.596, while the average friction coefficient of 42CrMo quenched and tempered steel is 0.670. The average friction coefficient of the sintered alloy is 0.084 lower than that of 42CrMo quenched and tempered steel. After calculating the volume wear rate, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of the sintered nickel-based alloy reaches 2.98, featuring high hardness and high wear resistance.

[0043] Example 4

[0044] 1. Powder mixing: Weigh 5.09% B4C powder, 5.56% Fe-72% Si powder, 25% Cr powder, 54.45% Ni powder, 4.95% Cu, and 4.95% Mo powder according to the mass ratio and add them to a mortar for 20 min of preliminary stirring and grinding. Then add the preliminarily mixed powder to a ball milling jar, add cemented carbide balls according to a ball-to-material ratio of 0.9:1, and add absolute ethanol according to a ratio of 24 ml / 100 g of powder. First, conduct 5 min of preliminary stirring and mixing of the powder, ball milling balls, and absolute ethanol, and then place the ball milling jar in a vibratory ball mill to start ball milling; the swing frequency of the vibratory mixer is 500 times / min, the amplitude of the tank body in the up and down direction is 30 mm, and the amplitude of the tank body in the front-back and left-right directions is 10 mm; after ball milling for 18 h, open the lid of the ball milling jar and place it in a vacuum drying oven for 10 h of drying. Then pass the dried powder through an 80-mesh sieve to separate the powder and ball milling balls, obtaining a powder with uniform mixing and good formability.

[0045] 2. Powder forming: Weigh 15 g of the mixed powder with an electronic balance, fill it into a stainless-steel mold, and adopt the up-and-down double-direction pressing method; the pressing pressure is 400 MPa, and the pressure holding time is 15 seconds; after demolding, a cylindrical green compact with a certain strength and density, with a diameter of Φ19.8 mm and a height of 5.2 mm, is obtained.

[0046] 3. Sintering: Put the green compact into a magnesia crucible, and then put it into an atmosphere tube furnace. After filling with a mixed gas of normal-pressure argon + 10 vol% hydrogen, start sintering. Heat the green body from room temperature to 200 °C at a heating rate of 1 °C / min, and keep it warm for 1 h; then heat it to 400 °C at a heating rate of 5 °C / min and keep it warm for 1 h; then heat it to 800 °C at a heating rate of 6 °C / min and keep it warm for 1 h; then heat it to 950 °C at a heating rate of 6 °C / min and keep it warm for 1 h; then heat it to 1075 °C at a heating rate of 5 °C / min and keep it warm for 1.5 h; cool it to room temperature with the furnace; take out the sintered sample to obtain the sintered nickel-based alloy.

[0047] The composition phases of the sintered nickel-based alloy prepared by the above method are: γ-Ni, Ni3B, M7(B,C)3, M 23 (B,C)6, and the hard phases M7(B,C)3, M 23 (B,C)6 are evenly distributed in the nickel matrix, and the hard phase M7(B,C)3 has a larger volume and a denser distribution. The relative density of this sintered alloy is 95.38%, and the hardness is 60.9 HRC. Figure 3 The friction coefficient curve of this sintered alloy is shown, and its average friction coefficient is 0.500, while the average friction coefficient of 42CrMo quenched and tempered steel is 0.670. The average friction coefficient of this sintered alloy is 0.170 lower than that of 42CrMo quenched and tempered steel. After calculating the volume wear rate, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this sintered nickel-based alloy reaches 3.95, featuring high hardness and high wear resistance.

[0048] Example 5

[0049] 1. Powder mixing: Weigh 5.09% B4C powder, 5.56% Fe-72% Si powder, 10% Cr powder, 67.15% Ni powder, 6.10% Cu, and 6.10% Mo powder according to the mass ratio, and add them to a mortar for 20 minutes of preliminary stirring and grinding; add the preliminarily mixed powder to a drum barrel, set the rotation speed to 18 r / min, and the mixing time is 24 h; after mixing, align the outlet of the mixer with the ground and take out the mixed powder; place the powder in a vacuum drying oven for 8 h, and then pass the dried powder through an 80-mesh sieve to obtain powder with good uniformity and formability.

[0050] 2. Powder forming: Weigh 22 g of the mixed powder using an electronic balance, fill it into a plastic sheath, place it in a sealed bag and conduct vacuum sealing treatment; use a pressure of 300 MPa in a cold isostatic press and hold the pressure for 50 min to obtain a cylindrical green compact with a diameter of Φ20 mm and a height of 8.2 mm, having a certain density and strength.

[0051] 3. Sintering: Place the green compact in an alumina boat and put it into an atmosphere muffle furnace together. After filling with normal-pressure nitrogen, start sintering. Heat the green body from room temperature to 200 °C at a heating rate of 2 °C / min, then hold for 0.5 h; then heat it to 400 °C at a heating rate of 4 °C / min and hold for 1 h; then heat it to 800 °C at a heating rate of 8 °C / min and hold for 1 h; then heat it to 950 °C at a heating rate of 5 °C / min and hold for 1 h; then heat it to 1050 °C at a heating rate of 6 °C / min and hold for 1.5 h; cool it to room temperature with the furnace; take out the sintered sample to obtain the sintered nickel-based alloy.

[0052] The composition phases of the sintered nickel-based alloy prepared by the above method are: γ-Ni, Ni3B, M7(B,C)3, M 23 (B,C)6. The hard phases M7(B,C)3, M 23 (B,C)6 are uniformly distributed in the nickel matrix, and the content of the hard phases M7(B,C)3, M 23 (B,C)6 is relatively small. The relative density of this sintered alloy is 96.65%, and the hardness is 57.3 HRC. Figure 3 The friction coefficient curve of this sintered alloy is shown in [reference], its average friction coefficient is 0.541, while the average friction coefficient of 42CrMo quenched and tempered steel is 0.670. The average friction coefficient of this sintered alloy is 0.129 lower than that of 42CrMo quenched and tempered steel. Through the calculation of the volume wear rate, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this sintered nickel-based alloy reaches 3.29, featuring high hardness and high wear resistance.

[0053] Example 6

[0054] 1. Powder mixing: Weigh 6.37% B4C powder, 6.96% Fe-72% Si powder, 16% Cr powder, 59.81% Ni powder, 5.43% Cu, and 5.43% Mo powder according to the mass ratio and add them to a mortar for 20 minutes of preliminary stirring and grinding; then add the preliminarily mixed powder to a ball mill jar, add cemented carbide balls according to a ball-to-material ratio of 1.1:1, and add absolute ethanol according to a ratio of 30 ml / 100 g of powder; first, perform 5 minutes of preliminary stirring and mixing of the powder, ball mill balls, and absolute ethanol, and then place the ball mill jar in a planetary ball mill to start ball milling; the rotation speed is 300 r / min, rotating clockwise and counterclockwise alternately, and the single-direction rotation time is 30 minutes; after ball milling for 20 hours, open the lid of the ball mill jar and place it in a vacuum drying oven for drying for 10 hours, and then pass the dried powder through an 80-mesh sieve to separate the powder and ball mill balls to obtain a powder with uniform mixing and good formability.

[0055] 2. Powder forming: Weigh 15 g of the mixed powder with an electronic balance and fill it into a cemented carbide mold, adopting an up-and-down two-way pressing method; the pressing pressure is 450 MPa, and the pressure holding time is 15 seconds; after demolding, a cylindrical green compact with a diameter of Φ19.8 mm and a height of 5.0 mm with a certain strength and density is obtained.

[0056] 3. Sintering: Place the green compact in an alumina boat and put it into an atmosphere tube furnace together. After filling with a mixed gas of normal pressure argon + 5 vol% hydrogen, start sintering. Heat the green body from room temperature to 200 °C at a heating rate of 1 °C / min and hold for 0.5 h; then heat it to 400 °C at a heating rate of 4 °C / min and hold for 1 h; then heat it to 800 °C at a heating rate of 6 °C / min and hold for 0.5 h; then heat it to 950 °C at a heating rate of 4 °C / min and hold for 1 h; then heat it to 1060 °C at a heating rate of 5 °C / min and hold for 2 h; cool it to room temperature with the furnace; take out the sintered sample to obtain a sintered nickel-based alloy. The composition phases of the sintered nickel-based alloy prepared by the above method are: γ-Ni, Ni3B, M7(B,C)3, M 23 (B,C)6, and the hard phases M7(B,C)3, M 23 (B,C)6 are evenly distributed in the nickel matrix, and the content of the hard phases M7(B,C)3, M 23 (B,C)6 is relatively large. The relative density of the sintered alloy is 98.03%, and the hardness is 59.4 HRC. Figure 3The friction coefficient curve of the sintered alloy is shown, with an average friction coefficient of 0.441, while the average friction coefficient of 42CrMo quenched and tempered steel is 0.670. The average friction coefficient of this sintered alloy is 0.229 lower than that of 42CrMo quenched and tempered steel. Through the calculation of the volume wear rate, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this nickel-based alloy reaches 4.09, featuring high hardness and high wear resistance. The descriptions of the friction test and the calculation of relative wear resistance in the above embodiments are as follows:

[0057] The test method adopted for the friction test is ball-on-disk friction. The counter ball is a Φ6mm silicon nitride ceramic ball, the rotation diameter is 6mm, the load is 30N, the rotation speed is 300r / min, the test time is 30min, and the sampling frequency is 1Hz during the test process; the mass of the specimen is measured before and after the friction test. The volume wear rate of the friction specimen is calculated according to Equation (1), and the relative wear resistance of the sintered nickel-based alloy is calculated according to Equation (2) with the obtained volume wear rate result:

[0058] W = (m1 - m2) / (ρ × F × L) (1)

[0059] β = W / W0 (2) <9000158>In Equation (1), W is the volume wear rate (mm 3 / (N×m)), m1 and m2 are the masses (g) of the specimen before and after the friction test respectively, ρ is the density of the sample (g / cm 3 ), F is the load (N), and L is the sliding distance (m); in Equation (2), β is the relative wear resistance of the sintered nickel-based alloy, W is the volume wear rate of the sintered nickel-based alloy (mm 3 / (N×m)), and W0 is the volume wear rate of 42CrMo quenched and tempered steel (mm 3 / (N×m)).

Claims

1. A sintered nickel-based alloy with high wear resistance, characterized in that: The mass percentages of the raw material powders used are as follows: B4C: 2.54% - 7.63%; Fe-72%Si: 2.78% - 8.33%; Cr: 16% - 25%; Ni, Cu, and Mo: 64.35% - 79.35%; where the mass ratio of Ni, Cu, and Mo is: 11:1:1; after the powders are mixed, formed, and sintered, the relative density is 95.38% - 98.62%, and the hardness is 56.1 - 60.9 HRC; If the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of the sintered nickel-based alloy is 2.98 - 4.31; the sintered nickel-based alloy has the characteristics of high density, high hardness and high wear resistance; the sintered nickel-based alloy involves solid-phase sintering and partial liquid-phase sintering at a temperature of 1025 - 1075 °C, achieving a relatively high degree of densification with a relative density of 95.38% - 98.62% at a lower sintering temperature, while maintaining the dimensional stability of the sintered product without significant shrinkage or deformation; in the sintered nickel-based alloy, the hard phases M7(B,C)3 and M 23 (B,C)6 are evenly distributed in the nickel matrix, playing a strengthening role and improving the hardness and wear resistance of the sintered nickel-based alloy.

2. The preparation method of a sintered nickel-based alloy with high wear resistance as described in claim 1, characterized in that: It includes the following steps: (1) Powder mixing: Prepare B4C powder, Fe-72%Si powder, Cr powder, Ni powder, Cu powder, and Mo powder according to the mass percentages of B4C: 2.54% - 7.63%, Fe-72%Si: 2.78% - 8.33%, Cr: 16% - 25%, Ni, Cu, and Mo: 64.35% - 79.35%, and where the mass ratio of Ni, Cu, and Mo is: 11:1:1; after weighing the powders, conduct powder mixing; after powder mixing, perform drying and sieving; the means of powder mixing include planetary ball milling mixing, vibratory ball milling mixing, V-type mixing, and drum mixing; (2) Powder forming: Cold press the dried powder using a mold or by cold isostatic pressing to obtain a green compact with a certain strength and density; the pressing pressure for cold pressing with a mold is 400 MPa - 600 MPa, and the pressure holding pressure for cold isostatic pressing is 200 MPa - 300 MPa; (3) Sintering: Transfer the green compact after powder forming into a sintering furnace capable of passing a protective atmosphere, and conduct sintering under the protective atmosphere to obtain a sintered nickel-based alloy; a segmented heating program is adopted during sintering, and the heating and sintering are completed under the protection of an argon, nitrogen, or argon + hydrogen mixed atmosphere; the segmented heating program is as follows: Heat the green compact from room temperature to 200°C at a heating rate of 1°C / min - 2°C / min, and then hold for 0.5 h - 1 h; then heat to 400°C at a heating rate of 4°C / min - 7°C / min, and hold for 0.5 h - 1 h; then heat to 800°C at a heating rate of 5°C / min - 8°C / min, and hold for 0.5 h - 1 h; then heat to 950°C at a heating rate of 4°C / min - 6°C / min, and hold for 1 h - 1.5 h; then heat to 1025°C - 1075°C at a heating rate of 5°C / min - 7°C / min, and hold for 1.5 h - 2 h; this segmented heating program is established based on the physical and chemical reaction process of the powder green compact; after sintering is completed, cool to room temperature with the furnace; take out the sintered sample to obtain a sintered nickel-based alloy.

3. The preparation method of a sintered nickel-based alloy with high wear resistance according to claim 2, wherein: For the planetary ball milling and mixing in step (1), first add the weighed powder into the ball milling tank, add ball milling balls according to a ball-to-material ratio of 0.8 - 1.2, and add absolute ethanol according to a ratio of 20 - 30 ml / 100 g of powder; first perform a preliminary stirring and mixing of the powder, ball milling balls, and absolute ethanol for 5 minutes, and then place the ball milling tank in the planetary ball mill to start ball milling; the revolution speed of the planetary ball mill is 200 - 300 r / min, rotating clockwise and counterclockwise alternately, and the single-direction rotation time is 30 minutes; after ball milling and mixing for 18 - 20 hours, open the lid of the ball milling tank and place it in a vacuum drying oven to dry for 8 - 10 hours, and then pass the dried powder through a sieve to separate the powder and ball milling balls, obtaining a mixed powder with uniform mixing and good formability.

4. The preparation method of a sintered nickel-based alloy with high wear resistance according to claim 2, characterized in that: For the vibratory ball milling and mixing in step (1), first add the weighed powder into the ball milling tank, add ball milling balls according to a ball-to-material ratio of 0.8 - 1.2, and add absolute ethanol according to a ratio of 20 - 30 ml / 100 g of powder; first perform a preliminary stirring and mixing of the powder, ball milling balls, and absolute ethanol for 5 minutes, and then place the ball milling tank in the vibratory ball mill to start ball milling; the swing frequency of the vibratory ball milling is 400 - 500 times / min, the amplitude of the tank body in the up and down direction is 30 - 40 mm, and the amplitude of the tank body in the front and back, left and right directions is 10 - 15 mm; after ball milling and mixing for 18 - 20 hours, open the lid of the ball milling tank and place it in a vacuum drying oven to dry for 8 - 10 hours, and then pass the dried powder through a sieve to separate the powder and ball milling balls, obtaining a mixed powder with uniform mixing and good formability.

5. The preparation method of a sintered nickel-based alloy with high wear resistance according to claim 2, characterized in that: The powder mixing in step (1) includes V-type mixing and drum mixing, which is to add the weighed powder into a drum or V-type cylinder, set the rotation speed to 18 - 20 r / min, and the mixing time to 20 - 24 hours; after the mixing is completed, take out the powder; place the powder in a vacuum drying oven to dry for 7 - 8 hours, and pass the dried powder through a sieve to obtain a mixed powder with uniform mixing and good formability.

6. The preparation method of a sintered nickel-based alloy with high wear resistance according to claim 2, characterized in that: The sintering in step (3) involves solid-phase sintering and partial liquid-phase sintering at a temperature of 1025 °C - 1075 °C, achieving a relatively high degree of densification of 95.38% - 98.62% at a relatively low sintering temperature, while maintaining the dimensional stability of the sintered product without significant shrinkage and deformation.

7. The preparation method of a sintered nickel-based alloy with high wear resistance according to claim 2, characterized in that: In the sintered nickel-based alloy described in step (3), the hard phases M7(B,C)3 and M 23 (B,C)6 are uniformly distributed in the nickel matrix, playing a strengthening role and improving the hardness and wear resistance of the sintered nickel-based alloy; the hardness reaches a relatively high level of 56.1 - 60.9 HRC. If the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of the sintered nickel-based alloy prepared by the present invention reaches 2.98 - 4.31, featuring high hardness and high wear resistance.

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