CN108380875B - A kind of tungsten-tungsten-plated diamond composite material with high thermal conductivity and its preparation method - Google Patents

Abstract

The invention discloses a tungsten-tungsten-coated diamond composite material with high thermal conductivity and a preparation method thereof, wherein the tungsten-tungsten-coated diamond composite material is made by mixing tungsten and tungsten-coated diamond according to the volume ratio, wherein the tungsten-coated diamond The mass fraction of diamond is 2%‑15%. The present invention uses tungsten-coated diamond particles for doping, and the existence of the tungsten-coated layer is more conducive to the diffusion between tungsten and carbon during the sintering process, so that the interface between the diamond and the tungsten substrate is better bonded, thereby obtaining better thermal conductivity . In the harsh thermal load environment of the reactor, it can reduce the damage of the PFM and the impact of plasma pollution caused by the damage of the material.

Description

A kind of tungsten-tungsten-plated diamond composite material with high thermal conductivity and its preparation method

technical field

The invention relates to a tungsten-based composite material and a preparation method thereof, in particular to a tungsten-tungsten-plated diamond composite material with high thermal conductivity and a preparation method thereof.

Background technique

With the development of human society, the demand for energy is increasing day by day, and the fusion energy produced by the fusion reaction of light atoms may become an effective solution to the energy problems faced by human beings. Tokamak is by far the most likely successful device for controlled thermonuclear fusion. However, in the fusion device, especially the plasma-facing material (PFM), it bears the influence of high H and He ion flux and high-energy neutron irradiation brought by the fusion reaction, and at the same time it is in direct contact with the edge plasma, a large amount of thermal energy The release of high-energy particles and electromagnetic radiation will cause serious surface damage to plasma-facing materials, degrade thermal and mechanical properties, and further affect the service life of materials. Therefore, there are high requirements on the performance of the material. Tungsten has the characteristics of high melting point (3410°C), low physical sputtering rate, low tritium retention, and low swelling. It is considered to be the most potential candidate material for the first wall.

However, tungsten-based materials still face many problems in the actual reactor environment, and PFM will be exposed to steady-state thermal loads and several types of transient thermal loads. These intense thermal loads can lead to cracks, surface melting, evaporation, droplet ejection, and fatigue fracture, which can lead to damage and plasma contamination of the PFM. Therefore, the material needs to have high thermal conductivity, and the general method of strengthening tungsten-based materials is to add a second phase (such as rare earth oxides and carbides) to the tungsten matrix to strengthen the material, but none of them can improve the thermal conductivity of tungsten-based materials. Conductivity, but will reduce the thermal conductivity of the material. Due to the excellent thermal conductivity of diamond itself, doping it into the tungsten matrix can greatly improve the thermal conductivity of the material and reduce the damage of the tungsten-based material in a high thermal load environment.

Contents of the invention

The invention aims to provide a tungsten-tungsten-plated diamond composite material with high thermal conductivity and a preparation method thereof. Compared with pure tungsten, the thermal conductivity of tungsten-tungsten-coated diamond composite prepared by sintering is significantly improved.

The tungsten-tungsten-coated diamond composite material with high thermal conductivity of the invention is made by mixing tungsten and tungsten-coated diamond according to volume ratio, wherein the mass fraction of tungsten-coated diamond is 2%-15%.

The present invention has the preparation method of the tungsten-tungsten-plated diamond composite material with high thermal conductivity, comprising the following steps:

Step 1: Milling

Stir and mix the pure tungsten powder and tungsten-coated diamond in a powder mixer at 300 rpm to obtain a mixed powder;

In step 1, the purity of the pure tungsten powder is 99.9%, and the particle size is 1.0-1.3 μm; the average particle size of the tungsten-coated diamond is 300 μm, and the thickness of the tungsten-coated layer is 200-300 nm.

Step 2: Sintering

Put the mixed powder obtained in step 1 into a graphite mold, then put the mold into a discharge plasma sintering furnace, vacuumize the furnace cavity at room temperature, then raise the temperature to 1600°C and keep it warm for 3 minutes, and then cool it down to room temperature after the heat preservation is completed, that is A tungsten-tungsten-coated diamond composite material is obtained.

In step 2, the heating rate is 100°C/min, and the cooling rate is 100°C/min.

In step 2, the pressure is controlled not to exceed 50 MPa during the sintering process.

The beneficial effects of the present invention are reflected in:

The diamond material itself has extremely high thermal conductivity (1500W/mK), far exceeding common high thermal conductivity materials such as copper (400W/mK). In the research of heat sink materials, diamond has been doped into the copper matrix to greatly improve the thermal conductivity. To improve the thermal conductivity of the material, the present invention dopes diamond into tungsten (160W/mK) to improve the thermal conductivity of the material. The present invention uses tungsten-coated diamond particles for doping, and the existence of the tungsten-coated layer is more conducive to the diffusion between tungsten and carbon during the sintering process, so that the interface between the diamond and the tungsten substrate is better bonded, thereby obtaining better thermal conductivity . In the harsh thermal load environment of the reactor, it can reduce the damage of the PFM and the impact of plasma pollution caused by the damage of the material.

Description of drawings

Figure 1 is a topographical view of tungsten-coated diamond particles. It can be seen from Figure 1 that a layer of tungsten coating is coated on the surface of the diamond particles.

Figure 2 is the fracture morphology of the composite material after sintering. From Figure 2, it can be seen that after sintering, the tungsten-coated diamond particles are evenly distributed in the tungsten matrix, and the interface with the tungsten matrix is well bonded, without obvious holes and voids.

Figure 3 is a line scan diagram of the interface between tungsten-coated diamond particles and the tungsten substrate. It can be seen from Figure 3 that the interdiffusion between tungsten and carbon elements occurs at the interface, and the formation of W _X C _X substances promotes the interfacial interaction. combined.

Figure 4 shows the thermal conductivity of composite materials with different mass fractions. It can be seen from Figure 4 that the doping of tungsten-coated diamond particles improves the thermal conductivity of tungsten-based materials.

Detailed ways

Example 1:

The tungsten-tungsten-coated diamond composite material with high thermal conductivity in this embodiment is made by mixing tungsten and tungsten-coated diamond according to volume ratio, wherein the mass fraction of tungsten-coated diamond is 2%. The purity of pure tungsten powder is 99.9%, and the particle size is 1.0-1.3 μm; the average particle size of tungsten-coated diamond is 300 μm, and the diamond particles are purchased from Henan Huanghe Cyclone Co., Ltd. 300nm.

The preparation method of the tungsten-tungsten-coated diamond composite material with high thermal conductivity in the present embodiment is as follows:

1. Powder making: Stir the pure tungsten powder and tungsten-coated diamond in a powder mixer at 300 rpm for 2 hours, and mix evenly to obtain a mixed powder;

2. Sintering: Put the mixed powder obtained in step 1 into a graphite mold, then put the mold into a discharge plasma sintering furnace, vacuumize the furnace cavity at room temperature, and raise the temperature to 1600°C at a heating rate of 100°C/min for 16 minutes ℃, keep it warm for 3 minutes, and then lower the temperature to room temperature at a cooling rate of 100 ℃/min, and control the pressure during sintering to not exceed 50MPa, that is, a tungsten-tungsten-coated diamond composite material is obtained.

After sintering, the diamond particles in the composite material are evenly distributed, and the thermal conductivity of the material reaches 173.1W/mK, which is higher than 160W/mK of pure W and 164.3W/mK of the uncoated tungsten-diamond composite material with the same mass fraction.

Example 2:

The tungsten-tungsten-coated diamond composite material with high thermal conductivity in this embodiment is made by mixing tungsten and tungsten-coated diamond according to volume ratio, wherein the mass fraction of tungsten-coated diamond is 5%. The purity of pure tungsten powder is 99.9%, and the particle size is 1.0-1.3 μm; the average particle size of tungsten-coated diamond is 300 μm, and the diamond particles are purchased from Henan Huanghe Cyclone Co., Ltd. 300nm.

The preparation method of the tungsten-tungsten-coated diamond composite material with high thermal conductivity in the present embodiment is as follows:

1. Powder making: Stir the pure tungsten powder and tungsten-coated diamond in a powder mixer at 300 rpm for 2 hours, and mix evenly to obtain a mixed powder;

2. Sintering: Put the mixed powder obtained in step 1 into a graphite mold, then put the mold into a discharge plasma sintering furnace, vacuumize the furnace cavity at room temperature, and raise the temperature to 1600°C at a heating rate of 100°C/min for 16 minutes ℃, keep it warm for 3 minutes, and then lower the temperature to room temperature at a cooling rate of 100 ℃/min, and control the pressure during sintering to not exceed 50MPa, that is, a tungsten-tungsten-coated diamond composite material is obtained.

After sintering, the diamond particles are evenly distributed in the composite material, and the thermal conductivity of the material reaches 222.8W/mK, which is higher than 160W/mK of pure W, and higher than 169.3W/mK of the uncoated tungsten-diamond composite material with the same mass fraction.

Example 3:

The tungsten-tungsten-coated diamond composite material with high thermal conductivity in this embodiment is made by mixing tungsten and tungsten-coated diamond according to volume ratio, wherein the mass fraction of tungsten-coated diamond is 15%. The purity of pure tungsten powder is 99.9%, and the particle size is 1.0-1.3 μm; the average particle size of tungsten-coated diamond is 300 μm, and the diamond particles are purchased from Henan Huanghe Cyclone Co., Ltd. 300nm.

The preparation method of the tungsten-tungsten-coated diamond composite material with high thermal conductivity in the present embodiment is as follows:

1. Powder making: Stir the pure tungsten powder and tungsten-coated diamond in a powder mixer at 300 rpm for 2 hours, and mix evenly to obtain a mixed powder;

2. Sintering: Put the mixed powder obtained in step 1 into a graphite mold, then put the mold into a discharge plasma sintering furnace, vacuumize the furnace cavity at room temperature, and raise the temperature to 1600°C at a heating rate of 100°C/min for 16 minutes ℃, keep it warm for 3 minutes, and then lower the temperature to room temperature at a cooling rate of 100 ℃/min, and control the pressure during sintering to not exceed 50MPa, that is, a tungsten-tungsten-coated diamond composite material is obtained.

After sintering, the diamond particles in the composite material are evenly distributed, and the thermal conductivity of the material reaches 241.5W/mK, which is higher than 160W/mK of pure W and 166.7W/mK of the uncoated tungsten-diamond composite material with the same mass fraction.

Claims (4)

1. a preparation method with high thermal conductivity of tungsten-tungsten-plated diamond composite material, is characterized in that comprising the steps: Step 1: Milling Stir and mix the pure tungsten powder and tungsten-coated diamond in a powder mixer at 300 rpm to obtain a mixed powder, in which the mass fraction of tungsten-coated diamond is 2%-15%; Step 2: Sintering Put the mixed powder obtained in step 1 into a graphite mold, then put the mold into a discharge plasma sintering furnace, vacuumize the furnace cavity at room temperature, then raise the temperature to 1600°C and keep it warm for 3 minutes, and then cool it down to room temperature after the heat preservation is completed, that is A tungsten-tungsten-coated diamond composite material is obtained. 2. The preparation method according to claim 1, characterized in that: In step 1, the purity of the pure tungsten powder is 99.9%, and the particle size is 1.0-1.3 μm; the average particle size of the tungsten-coated diamond is 300 μm, and the thickness of the tungsten-coated layer is 200-300 nm. 3. The preparation method according to claim 1, characterized in that: In step 2, the heating rate is 100°C/min, and the cooling rate is 100°C/min. 4. The preparation method according to claim 1, characterized in that: In step 2, the pressure is controlled not to exceed 50 MPa during the sintering process.