A method for preparing a thermal radiation dissipation in-situ ceramic-copper-based composite material layer

Abstract

This invention discloses a method for preparing an in-situ ceramic-copper matrix composite layer for heat radiation dissipation, including raw material weighing, powder mixing, cold pressing, vacuum sintering, processing, and testing. This invention significantly improves the thermal radiation coefficient of a pure copper conductive rod by in-situ synthesizing a ceramic-copper composite layer on its surface. Through reasonable elemental proportions, the thermal radiation coefficient is increased from 0.03-0.05 for pure copper to approximately 0.5-0.7. According to the Stefan-Boltzmann law, the radiation power will increase by 16.7-23.3 times. In the in-situ ceramic-copper matrix composite layer, the in-situ ceramic is distributed in a particulate form within the copper matrix. Therefore, the mesh-like copper matrix and the conductive rod form a chemical bond during sintering, thereby improving the composite layer's resistance to thermal shock and thermal vibration. Furthermore, the exothermic reaction during the in-situ reaction increases the local temperature, promoting metallurgical bonding between the conductive rod and the composite layer interface, and improving the interfacial bonding strength.

Description

Technical Field

[0001] This invention relates to the field of vacuum copper-based composite material thermal radiation layer preparation technology, specifically to a method for preparing an in-situ ceramic-copper composite material layer for thermal radiation heat dissipation. Background Technology

[0002] SF6 gas is widely used in electrical equipment such as GIS due to its excellent insulation and arc-quenching properties. However, its global warming potential (GWP) is 23,500 times that of CO2, making it one of the most potent greenhouse gases known to humankind. It not only causes environmental pollution but also poses hazards to maintenance personnel and equipment. Vacuum circuit breakers, with their environmental friendliness, safety, and reliability, have become the best alternative to SF6 circuit breakers. With the rapid expansion of my country's power grid capacity and the continuous improvement of voltage levels, developing high-reliability transmission-grade vacuum circuit breakers is the only way to achieve a "fluorine ban" in the power equipment sector, and it also represents a significant opportunity and challenge for China's power equipment industry.

[0003] During normal operation, the conductors of a vacuum switch convert some electrical energy into heat energy under continuous operation. However, the vacuum chamber itself has extremely poor heat dissipation capacity, as it cannot conduct heat effectively. Most of the heat generated is dissipated through the following methods: heat on the moving side of the vacuum chamber is transferred to the moving end guide flange via the conductive rod, and then to the moving side conductor; heat on the stationary side of the vacuum chamber is transferred to the stationary side support conductor through the contact surface. Heat is also dissipated through heat transfer between the moving and stationary conductors and the gas inside the circuit breaker. This single heat dissipation channel and poor gas flow result in poor heat dissipation, leading to a significant accumulation of heat on the moving and stationary conductors outside the vacuum chamber. This results in a high temperature rise during circuit breaker operation, making it difficult to meet the rated current requirements. Furthermore, insufficient heat dissipation capacity of the switchgear conductors during long-term operation causes temperature accumulation and overheating. Overheating inside the gas chamber is difficult to detect during routine inspections, and prolonged operation can cause burnout of electrical contact devices, leading to systemic power outages. The long-term heating of the vacuum switch directly affects the safe and reliable operation of the power lines and the service life of the switchgear.

[0004] Therefore, improving the heat dissipation capacity of the conductive rod in a vacuum interrupter and achieving heat accumulation control is not only fundamental to developing a new generation of high-capacity, high-reliability switchgear, but also crucial for extending the service life and reliability of switchgear and ensuring the safe and stable operation of the power grid. For this type of vacuum interrupter, due to the lack of a gaseous medium, convective heat transfer is essentially ineffective, and improving heat dissipation capacity can only be achieved through heat conduction and radiation from the moving and stationary sides of the conductive rod. Heat conduction mainly relies on the heat conduction of the conductive rod and heat dissipation at its ends. However, for high-voltage vacuum interrupters, relying solely on the overall optimization of the conductive rod (pure copper) and heat dissipation structure is insufficient to achieve effective thermal management. Therefore, in addition to structural optimization for heat conduction, further seeking heat radiation dissipation is a key factor in achieving thermal management of the vacuum interrupter. In a vacuum environment, heat can be transferred through electromagnetic waves (infrared radiation), following the Stefan-Boltzmann law: P=εσAT 4 Where P is the radiated power, ε is the emissivity, and σ is the Stefan-Boltzmann constant (5.67 × 10⁻⁶). −8 W / (m 2 ⋅K 4 Let A be the surface area and T be the absolute temperature. For the conductive rod of a vacuum interrupter, both the surface area and temperature are relatively fixed. Therefore, the emissivity of the conductive rod surface is the main factor affecting heat dissipation through radiation. Literature review shows that the emissivity of copper surface is only 0.02-0.05, which is basically insufficient for heat dissipation through radiation. Under the same conditions, for every 0.1 increase in ε, the radiated power increases by approximately 73 W / m² (at 100°C).

[0005] As shown above, applying a material with high emissivity to the surface of the conductive rod can significantly improve its heat dissipation capacity. In comparison, ceramics are a preferred material due to their naturally high emissivity (ε≈0.85–0.95), with a stable radiant power of 600–700 W / m² (at 100°C). Currently, researchers often use processes such as spraying, vapor deposition, and magnetron sputtering to coat ceramic layers. However, directly applying a pure ceramic coating to the surface of the conductive rod in a vacuum interrupter has the following key drawbacks: Insufficient interfacial bonding strength: The thermal expansion coefficients of ceramic and copper substrates differ significantly, and stress concentration is easily generated at the interface during thermal cycling, leading to coating peeling.

[0006] Poor thermal shock resistance: During the switching process of a vacuum switch, the conductive rod experiences instantaneous temperature changes and impacts. The brittle nature of pure ceramics makes it prone to crack initiation under thermal shock, which then propagates along the interface and leads to failure.

[0007] To address the aforementioned issues, there is an urgent need to develop and research key fabrication technologies for thermal radiation heat dissipation layers for conductive rods in vacuum environments. The aim is to enhance the interfacial bonding strength and thermal shock resistance between the heat dissipation layer and the conductive rod while ensuring good thermal radiation heat dissipation capabilities, thereby breaking through the bottleneck in improving the performance of thermal radiation layers and promoting the further development of thermal management technologies for vacuum interrupters and similar service environments. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: An in-situ ceramic-copper-based composite material layer with high heat dissipation capacity, wherein the in-situ ceramic-copper-based composite material layer is an in-situ ceramic-doped copper-based composite material, and its raw materials include matrix components and reinforcing components; The matrix components are composed of the following raw materials by weight: 30-50 parts copper; The reinforcing component is composed of the following raw materials by weight: 50 to 70 parts of titanium, graphite or boron carbide. The proportions of titanium powder, graphite powder, or boron carbide powder added are determined according to the in-situ reaction equation: Ti + C = TiC or 3Ti + B⁴C = 2TiB² + TiC To enable complete reaction between titanium powder and graphite powder or boron carbide; The Cu powder and Ti powder have a particle size of 10~48μm, and the C powder or B4C powder has a particle size of 100nm~1μm.

[0009] Preferably, by adjusting the amount of each element added in the reinforcing component, the difference between the density and porosity of the composite material layer phase is less than 3%.

[0010] This invention also discloses a method for preparing an in-situ ceramic-reinforced copper-based composite material layer, comprising the following steps: (1) Raw material weighing: Calculate the volume of the gap between the conductive rod and the mold, i.e. the volume of the composite material layer, to obtain the total weight of the required raw materials. Weigh the matrix components and reinforcing components according to the design ratio. (2) Powder mixing: Add the raw material powder weighed in step (1) to a planetary ball mill, use Al2O3 balls as the grinding medium, control the ball-to-material ratio between 1:6 and 1:10, mix for 24 to 30 hours at a speed of 50 to 80 rad / min to obtain a uniform mixed powder; (3) Cold pressing: When the conductive rod is a small diameter conductive rod, the mixed powder obtained in step (2) and the conductive rod are placed in mold I. During the powder loading process, every 80~100g of powder is loaded, and the punch is pressed once. After multiple powder loading and punch pressing, the mold is filled. After filling, a pressure of 20~100MPa is applied, and the pressure is held for 2~8min before the pressure is released to obtain the initial pressed blank. (4) Vacuum sintering: Place the initial compact obtained in step (3) into a crucible and put it into a vacuum sintering furnace. Heat it at a rate of 50~80℃ / min, and hold it at 350~400℃ and 650~700℃ for 30~40min each. Then continue to heat it to the in-situ reaction temperature of 750~850℃. After the reaction is completed, hold it for 8~10min. Finally, cool it to room temperature with the furnace to obtain the in-situ ceramic composite material layer blank. (5) Processing and testing: After cooling, the blank is machined by turning and other mechanical processing, and surface defects such as burrs are removed and polished to obtain the finished composite coated conductive rod; the heat dissipation capacity of the finished product is tested, and it can be applied on a large scale if it meets the expected standard.

[0011] The mold I includes an inner mold ring and an outer mold ring that are connected together. The inner mold ring consists of two semi-circular rings arranged opposite each other. A small-diameter conductive rod is provided inside the inner mold ring. A base for mounting the conductive rod and the inner mold ring is provided at the bottom of the inner mold ring. A positioning ring for mounting the conductive rod is provided at the center of the base. A cold-pressing punch is provided at the top of the outer mold ring and is sleeved on the conductive rod.

[0012] Preferably, the thickness of the outer ring of the mold is 30~40mm, and the ratio of the outer diameter d1 of the outer ring of the mold to the diameter d4 of the conductive rod is 2.0~2.2∶1; The ratio of the inner diameter d2 of the outer ring of the mold to the diameter d4 of the conductive rod is 1.3~1.5∶1; The thickness of the inner ring of the mold is 10-15mm, and the ratio of the inner diameter d3 of the inner ring of the mold to the diameter d4 of the conductive rod is 1.1-1.2:1. The thickness h1 of the base is 20~35mm, the inner diameter of the positioning ring is consistent with the diameter d4 of the conductive rod, and the height h2 of the positioning ring is 3~5mm. The ratio of the overall height of mold I to the height of the conductive rod is 1.1~1.2:1, wherein the height of the outer ring and the inner ring of the mold are consistent, and the ratio of the height of the cold pressing punch to the height of the mold is 0.5~0.8:1; The inner and outer rings of the mold are fitted with a clearance, with a tolerance of 0.12~0.15mm. The inner ring and base of mold I are made of graphite, while the remaining parts are made of heat-resistant mold steel.

[0013] Preferably, the outer in-situ ceramic-copper composite material layer is distributed on the outer side of the conductive rod and the inner side of the inner ring of the mold, with a thickness of 3 to 6 mm and distributed radially.

[0014] Preferably, when the conductive rod is large, step (3) uses mold II for cold pressing molding process, and the specific steps are as follows: (3.1) Powder loading: Place the mixed powder and conductive rod into mold II, place the rubber cap I at the bottom of the rubber sleeve, and place the whole thing on the horizontal vibrating table of the vibrator. While loading the powder, keep the vibrator running and tap the outside of the sleeve with a rubber mallet; leave a space of less than 1 / 6 of the sleeve volume, put on the rubber cap, and use a cold press to manually cold press. Then continue to load the powder and cold press until the powder is compacted and sealed. The gap between the rubber cap F and the sleeve is at most 2~3mm. (3.2) Cold isostatic pressing: Seal the rubber sleeve filled in (3.1) above. First, wrap the top and bottom of the rubber sleeve with rubber rings for two turns each, then wrap with tape in the radial direction, and finally vacuum pack with a vacuum bag. Place the packaged individual in a cold isostatic press, with water or oil as the medium, maintain the pressure at 180~220 MPa, and remove after holding the pressure for 5-15 minutes.

[0015] Mold II includes a hollow rubber sleeve, inside which a large-diameter conductive rod is placed. The upper and lower ends of the rubber sleeve are respectively provided with an upper rubber cover and a lower rubber cover. Both the upper and lower rubber covers include a rubber cover base and a boss protruding from the rubber cover base. The upper surface of the boss in the lower rubber cover is provided with a positioning columnar groove for the conductive rod.

[0016] Preferably, the ratio of the height of the rubber sleeve to the height of the conductive rod is 3:2, and the wall thickness of the rubber sleeve is 5~8mm; The ratio of the outer diameter d5 of the rubber sleeve to the diameter d7 of the conductive rod is 1.3~1.4:1, and the ratio of the inner diameter d6 to d7 of the rubber sleeve is 1.1~1.2:1. The upper and lower adhesive caps are at the same height, and the height of the upper and lower adhesive caps is 1 / 6 of the height of the adhesive sleeve. The ratio of the height h3 of the outer edge of the rubber cap base to the height h4 of the boss is 1:8; The outer wall of the boss is inclined, and the angle θ between it and the vertical direction is 1°~3°. The inner diameter of the positioning column groove is consistent with the diameter d7 of the conductive rod, and the height h5 of the positioning column groove is 3~5mm.

[0017] Preferably, the outer in-situ ceramic-copper composite material layer is distributed on the outer side of the conductive rod and the inner side of the rubber sleeve, with a thickness of 3-6 mm and distributed radially.

[0018] The advantages of this invention compared to the prior art are: This invention significantly improves the thermal emissivity of a pure copper conductive rod by in-situ synthesizing a ceramic-copper composite layer on its surface. Through a rational elemental ratio, the thermal emissivity is increased from 0.03-0.05 for pure copper to approximately 0.5-0.7. According to the Stefan-Boltzmann law, this translates to a 16.7-23.3-fold increase in radiant power. In the in-situ ceramic-copper composite layer, the ceramic particles are distributed within the copper matrix. Therefore, the mesh-like copper matrix and the conductive rod form a chemical bond during sintering, thereby enhancing the composite layer's resistance to thermal shock and thermal vibration. Furthermore, the exothermic reaction during the in-situ reaction raises the local temperature, promoting metallurgical bonding between the conductive rod and the composite layer interface and improving the interfacial bonding strength. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of mold I and conductive rod of the present invention.

[0020] Figure 2 This is a radial sectional view of the mold I and the conductive rod of the present invention.

[0021] Figure 3 This is a radial sectional view of the base of mold I of the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of mold II and conductive rod of the present invention.

[0023] Figure 5 This is a radial sectional view of the mold II and the conductive rod of the present invention.

[0024] Figure 6 This is a radial sectional view of the glue cap on mold II of the present invention.

[0025] Figure 7 This is a radial sectional view of the lower rubber cap of mold II of the present invention.

[0026] Figure 8 This is a microstructure diagram of the in-situ ceramic-copper-based composite material layer with high heat dissipation capacity prepared according to the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Example

[0028] An in-situ ceramic-copper-based composite material layer with high heat dissipation capacity, wherein the in-situ ceramic-copper-based composite material layer is an in-situ ceramic-doped copper-based composite material, and its raw materials include matrix components and reinforcing components; The matrix components are composed of the following raw materials by weight: 30-50 parts copper; The reinforcing component is composed of the following raw materials by weight: 50 to 70 parts of titanium, graphite or boron carbide. The proportions of titanium powder, graphite powder, or boron carbide powder added are determined according to the in-situ reaction equation: Ti + C = TiC or 3Ti + B⁴C = 2TiB² + TiC To enable complete reaction between titanium powder and graphite powder or boron carbide; The Cu powder and Ti powder have a particle size of 10~48μm, and the C powder or B4C powder has a particle size of 100nm~1μm. By adjusting the amount of each element added in the reinforcing component, the difference between the density and porosity of the composite material layer phase is made less than 3%.

[0029] A method for preparing an in-situ ceramic-reinforced copper-based composite material layer includes the following steps: (1) Raw material weighing: Calculate the volume of the gap between the conductive rod C and the mold I, that is, the volume of the composite material layer, and obtain the total weight of the required raw materials. Weigh the matrix components and reinforcing components according to the design ratio. (2) Powder mixing: Add the raw material powder weighed in step (1) to a planetary ball mill, use Al2O3 balls as the grinding medium, control the ball-to-material ratio between 1:6 and 1:10, mix for 24 to 30 hours at a speed of 50 to 80 rad / min to obtain a uniform mixed powder; (3) Cold pressing: When the conductive rod C is a small diameter conductive rod C, the mixed powder obtained in step (2) and the conductive rod C are placed in mold I. During the powder loading process, every 80~100g of powder is loaded, and the punch is pressed once. After multiple powder loading and punch pressing, the mold is filled. After filling, a pressure of 20~100MPa is applied, and the pressure is held for 2~8min before the pressure is released to obtain the initial pressed blank. (4) Vacuum sintering: Place the initial compact obtained in step (3) into a crucible and put it into a vacuum sintering furnace. Heat it at a rate of 50~80℃ / min, and hold it at 350~400℃ and 650~700℃ for 30~40min each. Then continue to heat it to the in-situ reaction temperature of 750~850℃. After the reaction is completed, hold it for 8~10min. Finally, cool it to room temperature with the furnace to obtain the in-situ ceramic composite material layer blank. (5) Processing and testing: After cooling, the blank is machined by turning and other mechanical processing, and surface defects such as burrs are removed and polished to obtain the finished composite coated conductive rod; the heat dissipation capacity of the finished product is tested, and it can be applied on a large scale if it meets the expected standard.

[0030] The mold I includes an inner mold ring B and an outer mold ring A connected together. The inner mold ring B consists of two semicircular rings arranged opposite each other. A small-diameter conductive rod C is disposed inside the inner mold ring B. A base D for mounting the conductive rod C and the inner mold ring B is disposed at the bottom of the inner mold ring B. A positioning ring for mounting the conductive rod C is disposed at the center of the base D. A cold-pressing punch E is disposed at the top of the outer mold ring A and is sleeved on the outside of the conductive rod C.

[0031] The thickness of the outer ring A of the mold is 30~40mm, and the ratio of the outer diameter d1 of the outer ring A of the mold to the diameter d4 of the conductive rod C is 2.0~2.2∶1; The ratio of the inner diameter d2 of the outer ring A of the mold to the diameter d4 of the conductive rod C is 1.3~1.5∶1; The thickness of the inner ring B of the mold is 10-15 mm, and the ratio of the inner diameter d3 of the inner ring B of the mold to the diameter d4 of the conductive rod C is 1.1-1.2:1. The thickness h1 of the base D is 20~35mm, the inner diameter of the positioning ring is consistent with the diameter d4 of the conductive rod C, and the height h2 of the positioning ring is 3~5mm. The height ratio of the mold I to the conductive rod C is 1.1~1.2:1, wherein the mold outer ring A and the mold inner ring B have the same mold height, and the height ratio of the cold pressing punch E to the mold height is 0.5~0.8:1. The inner ring B and outer ring A of the mold are fitted with a clearance fit, with a fit tolerance of 0.12~0.15mm; The inner ring B and base D of mold I are made of graphite, while the remaining parts are made of heat-resistant mold steel.

[0032] The outermost in-situ ceramic-copper composite material layer is distributed on the outer side of the conductive rod and the inner side of the inner ring B of the mold, with a thickness of 3-6 mm and distributed radially.

[0033] When the size of the conductive rod H is large, step (3) uses mold II for cold pressing molding process, and the specific steps are as follows: (3.1) Powder loading: Place the mixed powder and conductive rod H into mold II, place the rubber cap I at the bottom of the rubber sleeve G, and place the whole thing on the horizontal vibrating table of the vibrator. While loading the powder, keep the vibrator running and tap the outside of the sleeve with a rubber mallet; leave a space of less than 1 / 6 of the sleeve volume, put on the rubber cap F, and use a cold press to manually cold press. Then continue to load the powder and cold press until the powder is compacted and sealed. The gap between the rubber cap FF and the sleeve is at most 2~3mm. (3.2) Cold isostatic pressing: Seal the rubber sleeve G filled in (3.1) above. First, wrap the top and bottom of the rubber sleeve G with rubber rings for two turns each, then wrap it radially with tape, and finally vacuum pack it with a vacuum bag. Place the packaged individual in a cold isostatic press, with water or oil as the medium, maintain the pressure at 180~220 MPa, and remove it after holding the pressure for 5-15 minutes.

[0034] Mold II includes a hollow rubber sleeve G, inside which a large-diameter conductive rod H is placed. The upper and lower ends of the rubber sleeve G are respectively provided with an upper rubber cover F and a lower rubber cover I. Both the upper rubber cover F and the lower rubber cover I include a rubber cover base J and a boss K protruding from the rubber cover base J. The upper surface of the boss K in the lower rubber cover I is provided with a positioning columnar groove L for the conductive rod H.

[0035] The height ratio of the rubber sleeve G to the height of the conductive rod H is 3:2, and the wall thickness of the rubber sleeve G is 5~8mm; The ratio of the outer diameter d5 of the rubber sleeve G to the diameter d7 of the conductive rod H is 1.3~1.4:1, and the ratio of the inner diameter d6 to d7 of the rubber sleeve G is 1.1~1.2:1. The upper adhesive cap F and the lower adhesive cap I have the same height, and the height of the upper adhesive cap F and the lower adhesive cap I is 1 / 6 of the height of the adhesive sleeve G; The ratio of the height h3 of the outer edge of the rubber cap base J to the height h4 of the boss K is 1:8; The outer wall of the boss K is inclined, and the angle θ between it and the vertical direction is 1°~3°; The inner diameter of the positioning columnar groove L is consistent with the diameter d7 of the conductive rod H, and the height h5 of the positioning columnar groove L is 3~5mm.

[0036] The outermost in-situ ceramic-copper composite material layer is distributed on the outer side of the conductive rod and the inner side of the rubber sleeve G, with a thickness of 3-6 mm and distributed radially.

[0037] Specifically, an in-situ ceramic-copper composite layer with a volume fraction of 50% (mass fraction) was prepared. The in-situ ceramic was TiB2, with a content of 50% by volume fraction (33% by mass fraction). The microstructure is shown in the figure below. Figure 8As shown, the prepared in-situ ceramic-copper composite layer contains granular ceramic particles distributed within the copper matrix. Since the microstructure diagram reflects the morphology after corrosion, the copper matrix content is relatively low. In fact, the copper matrix accounts for 50% of the total volume and exhibits a network distribution.

[0038] The thermal emissivity was obtained by testing with an infrared thermal imager and a heating platform. The thermal emissivity of the in-situ ceramic-copper composite material layer was 0.45 at 100℃ and 0.39 at 150℃, which is much higher than that of pure copper (~0.03).

[0039] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A heat radiation in-situ ceramic-copper based composite material layer, characterized in that, The in-situ ceramic-copper composite material layer is an in-situ ceramic-doped copper-based composite material, the raw materials of which include matrix components and reinforcing components; The matrix components are composed of the following raw materials by weight: 30-50 parts copper; The reinforcing component is composed of the following raw materials by weight: 50 to 70 parts of titanium, graphite or boron carbide. The proportions of titanium powder, graphite powder, or boron carbide powder added are determined according to the in-situ reaction equation: Ti + C = TiC or 3Ti + B⁴C = 2TiB² + TiC To enable complete reaction between titanium powder and graphite powder or boron carbide; The Cu powder and Ti powder have a particle size of 10~48μm, and the C powder or B4C powder has a particle size of 100nm~1μm.

2. The heat radiation in-situ ceramic-copper matrix composite material layer according to claim 1, characterized in that, By adjusting the amount of each element added in the reinforcing component, the difference between the density and porosity of the composite material layer phase is made less than 3%.

3. A mold I for preparing the thermal radiation heat dissipation in-situ ceramic-copper matrix composite material layer of claim 1, characterized in that, The mold I includes an inner mold ring and an outer mold ring that are connected together. The inner mold ring consists of two semi-circular rings arranged opposite each other. A small-diameter conductive rod is provided inside the inner mold ring. A base for mounting the conductive rod and the inner mold ring is provided at the bottom of the inner mold ring. A positioning ring for mounting the conductive rod is provided at the center of the base. A cold-pressing punch is provided at the top of the outer mold ring and is sleeved on the conductive rod.

4. The mold I according to claim 3, characterized by The thickness of the outer ring of the mold is 30~40mm, and the ratio of the outer diameter d1 of the outer ring of the mold to the diameter d4 of the conductive rod is 2.0~2.2∶1; The ratio of the inner diameter d2 of the outer ring of the mold to the diameter d4 of the conductive rod is 1.3~1.5∶1; The thickness of the inner ring of the mold is 10-15mm, and the ratio of the inner diameter d3 of the inner ring of the mold to the diameter d4 of the conductive rod is 1.1-1.2:

1. The thickness h1 of the base is 20~35mm, the inner diameter of the positioning ring is consistent with the diameter d4 of the conductive rod, and the height h2 of the positioning ring is 3~5mm. The ratio of the overall height of mold I to the height of the conductive rod is 1.1~1.2:1, wherein the height of the outer ring and the inner ring of the mold are consistent, and the ratio of the height of the cold pressing punch to the height of the mold is 0.5~0.8:1; The inner and outer rings of the mold are fitted with a clearance, with a tolerance of 0.12~0.15mm. The inner ring and base of mold I are made of graphite, while the remaining parts are made of heat-resistant mold steel.

5. The mold I according to claim 3, wherein The outermost in-situ ceramic-copper composite material layer is distributed on the outer side of the conductive rod and the inner side of the inner ring of the mold, with a thickness of 3 to 6 mm and distributed radially.

6. A mold II for preparing the thermal radiation heat dissipation in-situ ceramic-copper matrix composite material layer according to claim 1, characterized in that, The device includes a hollow rubber sleeve, inside which a large-diameter conductive rod is placed. The upper and lower ends of the rubber sleeve are respectively provided with an upper rubber cover and a lower rubber cover. Both the upper and lower rubber covers include a rubber cover base and a boss protruding from the rubber cover base. The upper surface of the boss in the lower rubber cover is provided with a positioning columnar groove for the conductive rod.

7. The mold of claim 6, wherein The ratio of the height of the rubber sleeve to the height of the conductive rod is 3:2, and the wall thickness of the rubber sleeve is 5~8mm; The ratio of the outer diameter d5 of the rubber sleeve to the diameter d7 of the conductive rod is 1.3~1.4:1, and the ratio of the inner diameter d6 to d7 of the rubber sleeve is 1.1~1.2:

1. The upper and lower adhesive caps are at the same height, and the height of the upper and lower adhesive caps is 1 / 6 of the height of the adhesive sleeve. The ratio of the height h3 of the outer edge of the rubber cap base to the height h4 of the boss is 1:8; The outer wall of the boss is inclined, and the angle θ between it and the vertical direction is 1°~3°. The inner diameter of the positioning column groove is consistent with the diameter d7 of the conductive rod, and the height h5 of the positioning column groove is 3~5mm.

8. The mold II according to claim 6, characterized in that, The outer in-situ ceramic-copper composite material layer is distributed on the outer side of the conductive rod and the inner side of the rubber sleeve, with a thickness of 3 to 6 mm and distributed radially.

9. A method for preparing an in-situ ceramic-copper matrix composite material layer for heat radiation dissipation, characterized in that, Includes the following steps: (1) Raw material weighing: Calculate the volume of the gap between the conductive rod and the mold, i.e. the volume of the composite material layer, to obtain the total weight of the required raw materials. Weigh the matrix components and reinforcing components according to the design ratio. (2) Powder mixing: Add the raw material powder weighed in step (1) to a planetary ball mill, use Al2O3 balls as the grinding medium, control the ball-to-material ratio between 1:6 and 1:10, mix for 24 to 30 hours at a speed of 50 to 80 rad / min to obtain a uniform mixed powder; (3) Cold pressing: When the conductive rod is a small diameter conductive rod, the mixed powder obtained in step (2) and the conductive rod are placed in the mold I described in claim 3. During the powder loading process, every 80~100g of powder is loaded, and the punch is pressed once. After multiple powder loading and punch pressing, the mold is filled. After filling, a pressure of 20~100MPa is applied, and the pressure is held for 2~8min before the pressure is released to obtain the initial pressed blank. (4) Vacuum sintering: Place the initial compact obtained in step (3) into a crucible and put it into a vacuum sintering furnace. Heat it at a rate of 50~80℃ / min, and hold it at 350~400℃ and 650~700℃ for 30~40min each. Then continue to heat it to the in-situ reaction temperature of 750~850℃. After the reaction is completed, hold it for 8~10min. Finally, cool it to room temperature with the furnace to obtain the in-situ ceramic composite material layer blank. (5) Processing and testing: After cooling, the blank is machined by turning and other mechanical processing, and surface defects such as burrs are removed and polished to obtain the finished composite coated conductive rod; the heat dissipation capacity of the finished product is tested, and it can be applied on a large scale if it meets the expected standard.

10. The method for preparing an in-situ ceramic-copper matrix composite material layer for heat radiation dissipation according to claim 9, characterized in that, When the conductive rod is large, step (3) uses the mold II described in claim 5 for cold pressing molding process, and the specific steps are as follows: (3.1) Powder loading: Place the mixed powder and conductive rod into mold II, place the rubber cap I at the bottom of the rubber sleeve, and place the whole thing on the horizontal vibrating table of the vibrator. While loading the powder, keep the vibrator running and tap the outside of the sleeve with a rubber mallet; leave a space of less than 1 / 6 of the sleeve volume, put on the rubber cap, and use a cold press to manually cold press. Then continue to load the powder and cold press until the powder is compacted and sealed. The gap between the rubber cap F and the sleeve is at most 2~3mm. (3.2) Cold isostatic pressing: Seal the rubber sleeve filled in (3.1) above. First, wrap the top and bottom of the rubber sleeve with rubber rings for two turns each, then wrap with tape in the radial direction, and finally vacuum pack with a vacuum bag. Place the packaged individual in a cold isostatic press, with water or oil as the medium, maintain the pressure at 180~220 MPa, and remove after holding the pressure for 5-15 minutes.

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