Method for preparing nano-copper-based composite material through two-step sintering

Abstract

The invention discloses a method for preparing a nano copper-based composite material through two-step sintering, and belongs to the technical field of copper-based composite material preparation, Cu-Ti powder and B powder are used as original powder, precursor powder is obtained through high-energy ball milling, and a TiB2 / Cu composite material is prepared through the two-step sintering method. According to the method for preparing the nano-copper-based composite material through the two-step sintering, the nano-particles are formed through low-temperature sintering, sintering densification is achieved under the condition that the nano-particles are sintered at high temperature to inhibit grain coarsening, and the key technical problem that base body nano-grains grow up in the traditional high-temperature sintering process is solved; the mechanical property of the copper-based composite material is remarkably improved through the obtained nanocrystalline copper matrix and the nanometer dispersion particles together.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper-based composite material preparation, and particularly relates to a method for preparing a nano copper-based composite material through two-step sintering. BACKGROUND

[0002] Metal matrix composite is a strategic key material supporting the progress of multiple technical fields. Since TiB2 ceramic particles have excellent properties such as high melting point, high hardness, high electrical conductivity, good chemical stability and low density, the addition of TiB2 particles as a reinforcing phase in a Cu matrix can not only improve the strength and wear resistance of the material, but also maintain the good electrical conductivity of the Cu matrix. TiB2 / Cu composite material is a kind of copper-based composite material with important uses.

[0003] Powder metallurgy is an important means for preparing copper-based composite materials. A large number of nanocrystals can be introduced into metal powder through pre-stage high-energy ball milling, and nanocrystals are of great significance for improving the mechanical properties of copper-based composite materials. However, the thermal stability of nanocrystalline materials is poor, and will be severely coarsened after high-temperature sintering. Therefore, how to retain the nanostructure introduced in the ball milling stage in the microstructure after high-temperature sintering is the key to greatly improving the mechanical properties of powder metallurgy copper-based composite materials. SUMMARY

[0004] The purpose of the present application is to provide a method for preparing a nano copper-based composite material through two-step sintering, which forms nano particles through low-temperature sintering, and realizes sintering densification under the condition of inhibiting grain coarsening of nano particles through high-temperature sintering, solves the key technical problem of growth of matrix nanocrystalline grains in the traditional high-temperature sintering process, and significantly improves the mechanical properties of copper-based composite materials by the nano-crystalline copper matrix and nano-dispersed particles.

[0005] To achieve the above purpose, the present application provides a method for preparing a nano copper-based composite material through two-step sintering, comprising the following steps:

[0006] S1, Cu-Ti powder and B powder are weighed and placed in a ball mill jar, and stearic acid is added, and a precursor powder is obtained after ball milling;

[0007] S2, the precursor powder is low-temperature sintered to obtain a blank;

[0008] S3, the blank is high-temperature sintered to obtain a TiB2 / Cu composite material.

[0009] Preferably, in S1, the mass fraction of Ti element in Cu-Ti powder is 0.5-3.5%, the mass of B powder is 0.02-1.58% of the mass of Cu-Ti powder, and the mass of stearic acid is 1.67-2.33wt% of the total mass of Cu-Ti powder and B powder.

[0010] Preferably, in S1, argon is filled as a protective gas before ball milling, the ball-to-material ratio is (5-20):1, the ball milling speed is 100-150 r / min, and the ball milling time is 8-20 h.

[0011] Preferably, in S2, the low-temperature sintering temperature is 380-680 DEG C, the heating rate is 40-60 DEG C / min, the sintering pressure is 200-400 MPa, the holding time is 15-45 min, and the blank is obtained after furnace cooling to room temperature after the holding time.

[0012] Preferably, in S2, the low-temperature sintering is carried out in a rapid hot-pressing sintering furnace, and the vacuum degree is kept at 10 -2 ~ 10 -1 Pa during the sintering process.

[0013] Preferably, in S3, the high-temperature sintering temperature is 900-950 DEG C, the sintering pressure is 30-50 MPa, the holding time is 10-60 min, and the TiB2 / Cu composite material is obtained after furnace cooling to room temperature after the holding time.

[0014] Preferably, in S3, the high-temperature sintering is carried out in a vertical atmosphere sintering furnace or a rapid hot-pressing sintering furnace.

[0015] Preferably, when the vertical atmosphere sintering furnace is used for high-temperature sintering, N2 is introduced as a protective gas during the sintering process, and the heating rate is 10-30 DEG C / min.

[0016] Preferably, when the rapid hot-pressing sintering furnace is used for high-temperature sintering, the vacuum degree is kept at 10 -2 ~ 10 -1 Pa during the sintering process, and the heating rate is 25-100 DEG C / min.

[0017] Therefore, the method for preparing the nano copper-based composite material by the two-step sintering has the following beneficial effects:

[0018] (1) The Cu-Ti powder and the B powder are used as the original powder, the precursor powder is obtained through high-energy ball milling, and the TiB2 / Cu composite material is prepared by the two-step sintering method.

[0019] (2) The present application adopts two-step sintering method, sintering under low temperature and high pressure conditions. Since the sintering temperature is lower than the recrystallization temperature, the nanocrystals do not grow. Part of Ti reacts with B in situ to form nanometer TiB2 particles, which are dispersed in the Cu matrix. In the high-temperature sintering stage, the nanometer TiB2 particles play a pinning effect on the grain boundary, hindering the coarsening of the nanocrystalline Cu matrix formed in the ball milling stage, so that more nanocrystalline grains are retained, thereby realizing the fine-grain strengthening of the copper-based composite material. At the same time, the nanometer TiB2 particles are uniformly distributed in the Cu matrix, playing a role of dispersion strengthening. The nanocrystalline copper matrix obtained by two-step sintering and the nanometer dispersed particles together significantly improve the mechanical properties of the copper-based composite material.

[0020] The technical solutions of the present application will be further described in detail below by means of the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 2 is a TEM image of the TiB2 / Cu composite material produced by the method for preparing nanometer copper-based composite material by two-step sintering according to the present application, which is an embodiment 2. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be further described in detail below by means of the drawings and examples.

[0023] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those skilled in the art to which the present application belongs.

[0024] Example 1

[0025] The present application provides a method for preparing nanometer copper-based composite material by two-step sintering, comprising the following steps:

[0026] S1, taking Cu-Ti powder and B powder as the original powder, weighing 30g of Cu-Ti powder, the mass fraction of Ti element in the Cu-Ti powder is 3.02%, and the mass of B powder is 1.36% of the mass of Cu-Ti powder; the weighed original powder is placed in a ball milling tank, the ball-to-material ratio is 5:1, 0.7g of stearic acid is added to the ball milling tank, and the assembled ball milling tank is placed in a planetary ball mill; before ball milling, argon gas is filled into the tank as a protective gas; the ball milling speed is set to 100r / min, and the ball milling time is 8h; after ball milling, a precursor powder is obtained;

[0027] S2, placing the precursor powder in a hard alloy mold and placing it in a rapid hot-pressing sintering furnace for low-temperature sintering. The vacuum degree is maintained at 5×10 -2Pa; at room temperature, gradually pressurized to 300 MPa, then heated from room temperature to 680℃ at a rate of 50℃ / min, and kept for 15 min, and the pressure was kept until the end of the holding period, and then cooled and furnace-cooled to room temperature, to obtain a blank;

[0028] S3, the blank was placed in a graphite mold and put into a vertical atmosphere sintering furnace, N2 was introduced as a protective gas, and heated from room temperature to 950℃ at a rate of 20℃ / min, and kept for 60 min, and then a pressure of 30 MPa was applied, and the pressure was kept during the holding period, and then furnace-cooled after the holding period, and the pressure was kept until the temperature cooled to 700℃, and then the sample was taken out when the furnace cooled to room temperature, and finally a TiB2 / Cu composite material was obtained.

[0029] Example 2

[0030] The operation of this example was the same as that of Example 1, except that in S1, the ball-to-material ratio was 20:1, the ball milling speed was 125 r / min, and the ball milling time was 12 h; and in S2, the holding time was 30 min.

[0031] Example 3

[0032] The operation of this example was the same as that of Example 1, except that in S1, the ball-to-material ratio was 20:1, the ball milling speed was 150 r / min, and the ball milling time was 20 h; and in S2, the holding time was 45 min.

[0033] Example 4

[0034] The operation of this example was the same as that of Example 1, except that in S1, the ball-to-material ratio was 20:1, the ball milling speed was 125 r / min, and the ball milling time was 12 h; in S2, the temperature was raised from room temperature to 380℃, and the holding time was 30 min; and in S3, high-temperature sintering was carried out in a rapid hot-pressing sintering furnace, and the vacuum degree was kept at 5×10 -2 Pa, and heated from room temperature to 850℃ at a rate of 100℃ / min, then heated to 900℃ at a rate of 25℃ / min, and pressurized to 50 MPa, and kept for 10 min, and then cooled and furnace-cooled to room temperature after the holding period.

[0035] Example 5

[0036] The operation of this example was the same as that of Example 4, except that in S2, after the sample was put into the rapid hot-pressing sintering furnace, vacuum was started, and the vacuum degree was kept below 5×10 -2 Pa, and then heated from room temperature to 480℃ at a rate of 50℃ / min, and pressurized to 300 MPa, and kept for 30 min.

[0037] Example 6

[0038] The operation of this embodiment is the same as that of Example 5, except that the temperature is raised to 580℃ in S2.

[0039] The Vickers hardness and tensile strength of the TiB2 / Cu composite materials prepared in Examples 1-6 were tested, wherein the Vickers hardness was tested in accordance with GB / T 4340.1-2024 “Metallic Materials Vickers Hardness Test”, and the tensile strength was tested in accordance with GB / T 228.1-2021 “Metallic Materials Tensile Test”, and the test results are shown in Table 1. As can be seen from Table 1, the results of Examples 1-6 show that the composite material prepared by the present application has good Vickers hardness and tensile strength, and the nano-TiB2 reinforcing particles effectively inhibit the growth of the copper matrix grains, and the grain refinement can improve the strength of the composite material.

[0040] Table 1 Mechanical properties of TiB2 / Cu composite materials produced in Examples 1-6

[0041]

[0042] The microstructure of the TiB2 / Cu composite material prepared in Example 2 was analyzed by transmission electron microscopy, and the results are shown in Figure 1 From Figure 1 it can be seen that the TiB2 reinforcing particles are small in size and have a typical nanostructure, and are clearly visible in the nanocrystalline copper matrix. The nano-TiB2 reinforcing particles are in the form of near-spherical particles, and no obvious defects are observed.

[0043] Therefore, the method for preparing a nano-copper-based composite material in two steps as described above is used, i.e., first low-temperature sintering is performed to form nano-particles, and then sintering densification is achieved under the condition of high-temperature sintering of the nano-particles to inhibit grain coarsening. This solves the key technical problem of the growth of the nanocrystalline grains in the matrix during the traditional high-temperature sintering process, and the nanocrystalline copper matrix and the nano-dispersed particles together significantly improve the mechanical properties of the copper-based composite material.

[0044] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A two-step sintering method for preparing a nano copper-based composite material, characterized in that: The following steps are involved: S1. Weigh Cu-Ti powder and B powder, place them in a ball mill, add stearic acid, and ball mill to obtain a precursor powder; S2, sintering the precursor powder at a low temperature to obtain a blank; S3. Sintering the blank at a high temperature to obtain a TiB2 / Cu composite material.

2. The method for preparing a nano copper-based composite material by two-step sintering according to claim 1, characterized in that: In S1, the mass fraction of Ti element in Cu-Ti powder is 0.5-3.5%, the mass of B powder is 0.02-1.58% of the mass of Cu-Ti powder, and the mass of stearic acid is 1.67-2.33wt% of the total mass of Cu-Ti powder and B powder.

3. The method for preparing a nano copper-based composite material by two-step sintering according to claim 1, characterized in that: In S1, argon gas is filled as a protective gas before ball milling, the ball-to-material ratio is (5-20):1, the ball mill speed is 100-150 r / min, and the ball milling time is 8-20 h.

4. The method for preparing a nano copper-based composite material by two-step sintering according to claim 1, characterized in that: In S2, the low-temperature sintering temperature is 380-680°C, the heating rate is 40-60°C / min, the sintering pressure is 200-400 MPa, the holding time is 15-45 min, and after the holding is completed, the blank is cooled to room temperature with the furnace to obtain a blank.

5. The method for preparing a nano copper-based composite material by two-step sintering according to claim 1, characterized in that: In S2, low temperature sintering is carried out in a rapid hot pressing sintering furnace, and the vacuum degree is always maintained at 10 -2 ~10 -1 Pa.

6. The method for preparing a nano copper-based composite material by two-step sintering according to claim 1, characterized in that: In S3, the high-temperature sintering temperature is 900-950°C, the sintering pressure is 30-50 MPa, the holding time is 10-60 min, and after the holding is completed, the furnace is cooled to room temperature to obtain a TiB2 / Cu composite material.

7. The method for preparing a nano copper-based composite material by two-step sintering according to claim 1, characterized in that: In S3, high-temperature sintering is performed in a vertical atmosphere sintering furnace or a rapid hot pressing sintering furnace.

8. The method for preparing a nano copper-based composite material by two-step sintering according to claim 7, characterized in that: When a vertical atmosphere sintering furnace is used for high-temperature sintering, N2 is introduced as a protective gas during the sintering process, and the heating rate is 10 to 30°C / min.

9. The method for preparing a nano copper-based composite material by two-step sintering according to claim 7, characterized in that: When using a rapid hot pressing sintering furnace for high temperature sintering, the vacuum degree is always maintained at 10 -2 ~10 -1 Pa, heating rate is 25~100℃ / min.

Images