CN105039776A - Dispersion strengthening copper-based composite material for spot-welding electrode and preparation method of dispersion strengthening copper-based composite material - Google Patents

Abstract

The invention discloses a dispersion-strengthened copper-based composite material for spot welding electrodes and a preparation method thereof, belonging to the technical field of metal-based composite materials. The dispersion-strengthened copper-based composite material for spot welding electrodes consists of the following components in mass percent: TiC5-10%, Ce? 0.5-1%, La ₂ O ₃ ? 0.5-1%, Al ₂ O ₃ ? 0.1-1%, the balance is Cu. Among them, TiC has the characteristics of high hardness, high melting point, and good thermal stability, and TiC and Cu are insoluble in each other. The prepared composite material not only has the characteristics of high strength, high hardness, and high melting point of TiC, but also has the characteristics of high electrical conductivity and high melting point of Cu. High thermal conductivity and other characteristics, TiC can also improve the strength, wear resistance and high temperature resistance of copper; while the light rare earth element Ce and light rare earth oxide La ₂ O ₃ have the effect of strengthening grain boundaries and refining grains, which can improve the composite Material strength and processability.

Description

Dispersion-strengthened copper-based composite material for spot welding electrodes and preparation method thereof

technical field

The invention relates to a dispersion-strengthened copper-based composite material for spot welding electrodes and a preparation method for the composite material, belonging to the technical field of metal-based composite materials.

Background technique

High-strength and high-conductivity copper-based composites are a new type of functional material with excellent comprehensive properties. They not only have excellent electrical conductivity, but also have high strength and superior high-temperature performance. With the development of the electronics industry, especially after the American SCM company developed the Glidcop series Al ₂ O ₃ dispersion strengthened Cu composite materials in the late 1970s, the development and research of high-strength and high-conductivity copper-based composite materials in the United States, Japan and other developed countries is abnormal. Active, and has entered the practical stage. However, the research on this type of material started relatively late in our country. The research on this type of material was carried out in the late 1980s and early 1990s, but it has not yet entered the stage of practical application. It is often difficult to balance the wear resistance, electrical conductivity, strength and high temperature performance of pure copper and copper alloy materials of existing brands, and cannot fully meet the comprehensive performance requirements of the rapid development of aviation, aerospace, microelectronics and other high-tech, such as microelectronics Electrode material requirements for device spot welding: hardness ≥ 110HBS, electrical conductivity ≥ 85% IACS, high temperature softening temperature ≥ 923K.

Dispersed copper is an excellent electronic structural functional material with high wear resistance, high conductivity, high strength, and high resistance to softening temperature. It is widely used in high-power electric vacuum tubes, microelectronic device pins, integrated circuit lead frames, microwave communications, electric power Transportation and other fields are widely used in the defense industry and electronic information industry.

The traditional manufacturing technology of dispersed copper mostly adopts powder metallurgy method, among which powder internal oxidation powder metallurgy method is the most widely used, and its common technical process is: alloy smelting → powder making → internal oxidation → reduction → pressing → sintering → thermal processing → cold processing. Due to the complex process of this manufacturing technology, it is difficult to control the quality of materials and the cost is very high, which greatly limits its popularization and application. Most of the dispersed copper in the Chinese market is the product of American and Japanese companies, and the domestic scale is very small, which is difficult to meet the needs of national defense and social development.

Dispersion-strengthened Al ₂ O ₃ -Cu composite material not only has high strength, electrical conductivity similar to that of pure copper, but also has good resistance to arc ablation, electrical wear resistance and high normal temperature strength and high temperature strength. New structural and functional materials with broad application prospects. With the development of the electronics industry, the demand for such high wear-resistant, high-purity, high-conductivity composite materials is increasing.

The development of dispersion strengthened copper is mainly the development of preparation technology. The key to the preparation technology of dispersion-strengthened copper is how to obtain ultra-fine strengthening particles evenly distributed on the highly conductive pure copper matrix, so as to obtain a high-conductivity copper-based composite material with high dispersion strengthening effect. The main development of its preparation technology has experienced the traditional powder metallurgy method, improved powder metallurgy method and other preparation new technologies.

The strength of dispersion-strengthened materials depends not only on the nature of the matrix and dispersed phase, but also on the content, particle size and distribution, shape, and combination of the dispersed phase and the matrix, as well as on the preparation process (such as processing methods, processing conditions) related. Due to the low ductility of dispersion strengthened materials, it needs to be paid attention to and improved, but the superiority of dispersion strengthened materials in performance still dominates.

Chinese patent (Application No.: 201210361535.2) discloses a preparation method of a high-wear-resistant, high-strength, high-conductivity spot welding electrode, which includes the following steps: (1) Weigh Cu ₂ O, Cu-Al, and TiC powders respectively, mix them in Ball mill for 12 to 16 hours at a rotational speed of 30 rpm; the particle size of Cu ₂ O powder is 200 mesh, and the dosage is 2.5 to 5% of the mass of the Cu-Al alloy; the particle size of Cu-Al powder is 200 mesh, and the aluminum content in Cu-Al is not more than 0.5 wt%; the particle size of the TiC powder is 20-60mm, accounting for 12.14-26.56% of the total mass of the mixed powder; (2) the mixed powder after ball milling is packed into a graphite mold, and pre-compressed for 5min under the condition of 30MPa; (3) the step (2) The pre-pressed mold filled with mixed powder is placed in a vacuum hot-pressing sintering furnace, and hot-pressed at a sintering temperature of 900-1000°C, a vacuum degree of 1.5×10 ^-2 MPa, and a pressing pressure of 20-40 MPa. Sintering for 1-2 hours, then removing the pressure and sintering for 1-4 hours to obtain fully internally oxidized dispersed copper; (4) Process the dispersed copper in step (3) into a product of required size. The dispersed copper spot welding electrode prepared by this method has the characteristics of high wear resistance, high strength, high electrical conductivity, and high resistance to softening temperature, wherein the electrical conductivity of the dispersed copper-TiC (30%) is 82.6% IACS, and the microhardness is 175HV. The density is 99.15%, the thermal conductivity is 90.14W·m ^-1 ·K ^-1 , the service life of spot welding electrodes (soldering spots) is 68,000 to 72,000 times, and the softening temperature is higher than 650°C. However, the electrical conductivity of the spot welding electrode material is lower than the electrical conductivity ≥ 85% IACS standard of the spot welding electrode material for microelectronic devices, and the softening temperature, electrical conductivity and softening resistance still need to be improved.

Contents of the invention

The object of the present invention is to provide a dispersion-strengthened copper-based composite material for spot welding electrodes.

At the same time, the present invention also provides a preparation method of the above-mentioned dispersion strengthened copper-based composite material.

In order to achieve the above object, the technical solution adopted in the present invention is:

A dispersion-strengthened copper-based composite material for spot welding electrodes, which consists of the following components in mass percentages: TiC 5-10%, Ce 0.5-1%, La ₂ O ₃ 0.5-1%, Al ₂ O ₃ 0.1-1 %, the balance is Cu. The composite material can be prepared by the method described in the background art, except that Ce powder and La ₂ O ₃ powder are added in step (1).

A dispersion-strengthened copper-based composite material for spot welding electrodes, which is made of the following raw materials in mass percentages: 5-10% of TiC powder, 0.5-1% _of Ce powder, 0.5-1% of _La2O3 powder, and a reaction amount of Cu ₂ O powder, the balance is Cu-Al alloy powder, and the Al content in the Cu-Al alloy powder is not more than 0.5wt%.

The particle size of the TiC powder is 5-15 μm, and the median particle size is 10 μm.

The particle size of the Ce (used as interface binding agent) powder is 0.5-3 μm.

The particle size of the La ₂ O ₃ (used as an activator) powder is 0.2-1 μm.

The Al content in the Cu-Al alloy powder is preferably 0.1-0.5 wt%, and correspondingly, the mass percentage of Cu ₂ O powder in the raw material is 0.5-4%.

The Cu ₂ O powder has a particle size of 20-60 μm, with a median particle size of 30 μm, and mainly provides an oxygen source for internal oxidation.

The particle size of the Cu-Al alloy (low solid solubility alloy) powder is lower than 200 mesh. Cu-Al alloy powder can be prepared by conventional water spray method.

A preparation method of a dispersion-strengthened copper-based composite material for a spot welding electrode, comprising the following steps:

(1) Take each raw material according to the mass percentage, mix and ball-mill the five kinds of powders until the particle size is less than 200 mesh but not more than 400 mesh;

(2) Put the mixed powder after ball milling into a mold, and carry out vacuum hot pressing sintering. The sintering temperature is 980-1030°C, the internal oxidation time is 1-3h, the pressing pressure is 35-55MPa, and the total pressing time is 0.5- After 1h, the dispersed copper-based composite material was obtained.

The ball milling in the step (1) can adopt QM-3SP20 planetary ball mill, and ball milling at 35-45 rpm for 1.5-3 hours.

After the mixed powder is loaded into the mold in step (2), it is pre-pressed first, and then vacuum hot-pressed and sintered. The pressure of pre-compression is 50-100MPa, and the time is 10-20min. The purpose of pre-compacting is to ensure complete compaction of the mixed powder.

The vacuum hot pressing sintering in step (2) uses a VPF-350 vacuum hot pressing furnace, and the whole pre-pressed mold with the mixed powder is placed in the vacuum hot pressing furnace for vacuum hot pressing sintering and internal oxidation.

In the step (2), the vacuum degree of the vacuum hot pressing sintering is 1.0×10 ^-2 ~1.0×10 ^-4 Pa.

In the process of vacuum hot pressing sintering in step (2), there is a pressurization-relieving operation, and the total pressurization time is the sum of several sections of pressing time, which does not include the pre-pressing time.

After the dispersed copper-based composite material is obtained in step (2), it is processed and deformed to obtain a spot welding electrode. The processing deformation is cold extrusion deformation, hot extrusion deformation or rolling deformation. For complex-shaped microelectronic devices or spot welding electrode parts, while meeting the size requirements, the strength of dispersed copper can be further improved by cold deformation, and due to the dispersed distribution of nano-alumina particles and fine-grained titanium carbide, this The deformation hardening effect is retained to higher temperatures. Cold (hot) extrusion deformation can be formed by one-time extrusion or multi-pass rolling.

Beneficial effects of the present invention:

In the present invention, the dispersed copper-based composite material adopts TiC, light rare earth Ce and light rare earth _{oxide La2O3} powder, wherein TiC has the characteristics of high hardness, high melting point and good thermal stability, and TiC particles (or fiber), TiC and Cu are insoluble in each other, and the prepared composite material not only has the characteristics of high strength, high hardness, and high melting point of TiC, but also has the characteristics of high electrical conductivity and high thermal conductivity of Cu. In addition, TiC can also improve the strength and resistance of copper. Abrasion resistance and high temperature resistance. The light rare earth element Ce and the light rare earth oxide La ₂ O ₃ can strengthen the grain boundary and refine the grain, which can improve the strength and processability of the composite material.

The spot welding electrode prepared by using the dispersed copper-based composite material of the present invention has characteristics such as high strength, high wear resistance, high conductivity, high resistance to softening temperature, and high resistance to arc erosion. The electrical conductivity is above 85% IACS, and the density is higher than 98%, the service life is 9 to 10 times higher than that of conventional copper alloy spot welding electrodes, and the softening temperature reaches above 690 ° C. It can be used for high-power electric vacuum tubes, microelectronic device pins, integrated circuit lead frames, microwave communications, power transmission, etc. It is also widely used in national defense industry and electronic information industry.

The preparation method of the dispersed copper-based composite material in the invention has the advantages of short internal oxidation time, low cost and high efficiency, and is suitable for large-scale industrial production.

Detailed ways

The following examples only illustrate the present invention in further detail, but do not constitute any limitation to the present invention.

Example 1

The dispersion-strengthened copper-based composite material for spot welding electrodes in this embodiment consists of the following components in mass percent: _TiC8 %, _Ce0.7 %, _La2O30.8 %, _Al2O30.1 %, and the balance is Cu. The composite material is prepared with reference to the method described in the background art, except that Ce powder and La ₂ O ₃ powder are added in step (1).

Example 2

The dispersion-strengthened copper-based composite material for spot welding electrodes in this embodiment consists of the following components in mass percentages: _TiC5 %, _Ce0.5 %, _La2O30.5 %, _Al2O30.5 %, and the balance is Cu. The preparation method is the same as in Example 1.

Example 3

The dispersion-strengthened copper-based composite material for spot welding electrodes in this embodiment is composed of the following components in mass percentage: TiC 10%, Ce 1%, La ₂ O ₃ 1%, Al ₂ O ₃ 1%, and the balance is Cu. The preparation method is the same as in Example 1.

Example 4

The dispersion-strengthened copper-based composite material for spot welding electrodes in this embodiment is made of the following raw materials in mass percent: TiC powder (particle size 10 μm) 8%, Ce powder (particle size 1 μm) 0.7%, La ₂ O ₃ powder (particle size 0.5 μm) 0.8%, Cu ₂ O powder (particle size 30 μm) 0.8%, the balance is Cu-Al alloy powder (particle size 200 mesh), the Al content in Cu-Al alloy powder is 0.09%.

A method for preparing a dispersion-strengthened copper-based composite material for spot welding electrodes, comprising the following steps:

(1) Take each raw material according to the above mass percentages, mix the five powders and place them on a QM-3SP20 planetary ball mill, and ball mill them for 2 hours at a speed of 30 rpm to obtain a mixed powder with a particle size of 300 mesh;

(2) Put the ball-milled powder into a graphite mold (the cavity size is φ50mm×30mm), pre-press for 20min under a pressure of 50MPa, and then put the whole mold together in a VPF-350 vacuum hot-press furnace for vacuum hot-press sintering , the vacuum degree is 1.5×10 ^-3 Pa, the sintering temperature is 1000°C, the internal oxidation time is 2h, the internal oxidation is 30min and then pressurized for 20min, the pressing pressure is 45MPa, then the pressure is released for 30min, and then pressurized for 40min, the total pressurization The time is 1 h, and the overall TiC/Ce/La ₂ O ₃ /Cu-Al ₂ O ₃ block with complete internal oxidation and a density of 99.3% is obtained.

The dispersion-strengthened copper-based composite material prepared above contains Cu, Al, Ti, C, Ce, La and O elements, wherein Al and O exist in the form of the second phase of alumina, and the content of Al ₂ O ₃ is 0.17wt%, Ti and C exist in the form of TiC reinforcing phase (content 8wt%), Ce is an interfacial bonding agent (content _0.7wt %), La and O exist as _La2O3 as activator and interfacial bonding enhancer (content 0.8wt%) %), and the balance is Cu.

Cut the overall TiC/Ce/La ₂ O ₃ /Cu-Al ₂ O ₃ pieces into small pieces with a diameter of 7 mm and a length of 30 mm with a sawing machine, heated to 900 ° C in a SXL-1200 box-type resistance furnace, kept it for 30 min, and then Spot welding electrodes for microelectronic devices with a diameter of 4mm are hot-extruded on a YT32-400 four-column hydraulic press. The electrical conductivity of the obtained electric welding electrode material is 86.8%, the hardness is 185HV, the service life of the electric welding electrode is 72,000 to 75,000 times, and the softening temperature is higher than 698°C.

Example 5

The dispersion-strengthened copper-based composite material for spot welding electrodes in this embodiment is made of the following raw materials in mass percent: TiC powder (particle size 10 μm) 5%, Ce powder (particle size 0.5 μm) 0.5%, La ₂ O ₃ powder ( particle size 0.2 μm) 0.5%, Cu ₂ O powder (particle size 30 μm) 2.5%, the balance is Cu-Al alloy powder (particle size 200 mesh), the Al content in Cu-Al alloy powder is 0.3%.

A method for preparing a dispersion-strengthened copper-based composite material for spot welding electrodes, comprising the following steps:

(1) Take each raw material according to the above mass percentages, mix the five powders and place them on a QM-3SP20 planetary ball mill, and ball mill them for 2 hours at a speed of 30 rpm to obtain a mixed powder with a particle size of 300 mesh;

(2) Put the ball-milled powder into a graphite mold (the cavity size is φ50mm×30mm), pre-press for 20min under a pressure of 50MPa, and then put the whole mold together in a VPF-350 vacuum hot-press furnace for vacuum hot-press sintering , the vacuum degree is 1.5×10 ^-3 Pa, the sintering temperature is 980°C, the internal oxidation time is 2h, the internal oxidation is 30min and then pressurized for 20min, the pressing pressure is 35MPa, then the pressure is released for 30min, and then pressurized for 40min, the total pressurization The time is 1 h, and the overall TiC/Ce/La ₂ O ₃ /Cu-Al ₂ O ₃ block with complete internal oxidation and a density of 99.0% is obtained.

The dispersion-strengthened copper-based composite material prepared above contains Cu, Al, Ti, C, Ce, La and O elements, wherein Al and O exist in the form of the second phase of alumina, and the content of Al ₂ O ₃ is 0.52wt%, Ti and C exist in the form of TiC reinforcing phase (content 5wt%), Ce is an interfacial bonding agent (content 0.5wt%), La and O exist as _La2O3 as activator and interfacial bonding enhancer (content 0.5wt% ₎ %), and the balance is Cu.

Cut the overall TiC/Ce/La ₂ O ₃ /Cu-Al ₂ O ₃ pieces into small pieces with a diameter of 7 mm and a length of 30 mm with a sawing machine, heated to 900 ° C in a SXL-1200 box-type resistance furnace, kept it for 30 min, and then Spot welding electrodes for microelectronic devices with a diameter of 4mm are hot-extruded on a YT32-400 four-column hydraulic press. The electrical conductivity of the obtained electric welding electrode material is 86.5%, the hardness is 182HV, the service life of the electric welding electrode is 69,000 to 73,000 times, and the softening temperature is higher than 694°C.

Example 6

The dispersion-strengthened copper-based composite material for spot welding electrodes in this embodiment is made of the following raw materials in mass percent: TiC powder (particle size 10 μm) 10%, Ce powder (particle size 3 μm) 1.0%, La ₂ O ₃ powder (particle size 1 μm) 1.0%, Cu ₂ O powder (particle size 30 μm) 3.7%, the balance is Cu-Al alloy powder (particle size 200 mesh), the Al content in Cu-Al alloy powder is 0.42%.

A method for preparing a dispersion-strengthened copper-based composite material for spot welding electrodes, comprising the following steps:

(1) Take each raw material according to the above mass percentages, mix the five powders and place them on a QM-3SP20 planetary ball mill, and ball mill them for 2 hours at a speed of 30 rpm to obtain a mixed powder with a particle size of 300 mesh;

(2) Put the ball-milled powder into a graphite mold (the cavity size is φ50mm×30mm), pre-press for 20min under a pressure of 50MPa, and then put the whole mold together in a VPF-350 vacuum hot-press furnace for vacuum hot-press sintering , the vacuum degree is 1.5×10 ^-3 Pa, the sintering temperature is 1030°C, the internal oxidation time is 2h, the internal oxidation is 30min, and then pressurized for 20min, the pressing pressure is 55MPa, then the pressure is released for 30min, and then pressurized for 40min, the total pressurization The time is 1 h, and the overall TiC/Ce/La ₂ O ₃ /Cu-Al ₂ O ₃ block with complete internal oxidation and a density of 98.7% is obtained.

The dispersion-strengthened copper-based composite material prepared above contains Cu, Al, Ti, C, Ce, La and O elements, wherein Al and O exist in the form of the _second phase of alumina, and the content of _Al2O3 is 0.8wt%, Ti and C exist in the form of TiC reinforcing phase (content 10wt%), Ce is an interfacial bonding agent (content 1.0wt%), La and O exist as _La2O3 as activator and interfacial bonding enhancer (content 1.0wt% ₎ %), and the balance is Cu.

Cut the overall TiC/Ce/La ₂ O ₃ /Cu-Al ₂ O ₃ pieces into small pieces with a diameter of 7 mm and a length of 30 mm with a sawing machine, heated to 900 ° C in a SXL-1200 box-type resistance furnace, kept it for 30 min, and then Spot welding electrodes for microelectronic devices with a diameter of 4mm are hot-extruded on a YT32-400 four-column hydraulic press. The electrical conductivity of the obtained electric welding electrode material is 85.7%, the hardness is 178HV, the service life of the electric welding electrode is 65,000 to 71,000 times, and the softening temperature is higher than 692°C.

In the above examples, the QM-3SP20 star ball mill was purchased from Henan Brother Instrument Equipment Co., Ltd.; the VPF-350 vacuum hot-pressing sintering furnace was purchased from Yixing Jingwei Electric Furnace Co., Ltd.; the SXL-1200 box-type resistance furnace was purchased from Zhengzhou Honglang Instrument Equipment Co., Ltd. ; The four-column hydraulic press YT32-400 was purchased from Tengzhou Fangteng Machinery Factory.

Claims (10)

1. A dispersion-strengthened copper-based composite material for spot welding electrodes, characterized in that: it consists of the following components in mass percent: TiC5～10%, Ce0.5～1%, La ₂ O ₃ 0.5～1%, Al ₂ O ₃ 0.1-1%, the balance is Cu. 2. A dispersion-strengthened copper-based composite material for spot welding electrodes, characterized in that: it is made of the raw materials in the following mass percentages: TiC powder 5-10%, Ce powder 0.5-1%, La ₂ O ₃ powder 0.5-1 %, Cu ₂ O powder is 0.5-4%, the balance is Cu-Al alloy powder, and the Al content in Cu-Al alloy powder is 0.1-0.5wt%. 3. The dispersion-strengthened copper-based composite material according to claim 2, characterized in that the particle size of the TiC powder is 5-15 μm. 4. The dispersion-strengthened copper-based composite material according to claim 2, characterized in that the particle size of the Ce powder is 0.5-3 μm. 5. The dispersion-strengthened copper-based composite material according to claim 2, characterized in that the particle size of the La ₂ O ₃ powder is 0.2-1 μm. 6 . The dispersion strengthened copper matrix composite material according to claim 2 , characterized in that: the particle size of the Cu ₂ O powder is 20-60 μm. 7. The dispersion strengthened copper matrix composite material according to claim 2, characterized in that the particle size of the Cu-Al alloy powder is lower than 200 mesh. 8. The preparation method of the dispersion-strengthened copper-based composite material for spot welding electrodes as claimed in any one of claims 2 to 7, characterized in that: comprising the following steps: (1) Take each raw material according to the mass percentage, mix and ball-mill the five kinds of powders until the particle size is less than 200 mesh but not more than 400 mesh; (2) Put the mixed powder after ball milling into a mold, and carry out vacuum hot pressing sintering. The sintering temperature is 980-1030°C, the internal oxidation time is 1-3h, the pressing pressure is 35-55MPa, and the total pressing time is 0.5- After 1h, the dispersed copper-based composite material was obtained. 9. The preparation method according to claim 8, characterized in that: after the mixed powder is loaded into the mold in step (2), pre-pressing is carried out first, and then vacuum hot-pressing sintering is carried out, the pre-pressing pressure is 50-100 MPa, the time 10-20 minutes. 10. The preparation method according to claim 8, characterized in that: the vacuum degree of vacuum hot pressing sintering in step (2) is 1.0×10 ^-2 ~1.0×10 ^-4 Pa.