Interface modified diamond / aluminum-based composite material, insulator hardware and preparation process of interface modified diamond / aluminum-based composite material

Abstract

The invention discloses an interface modified diamond / aluminum-based composite material, an insulator fitting and a preparation process of the interface modified diamond / aluminum-based composite material, the composite material takes high-purity aluminum or aluminum alloy as a matrix, micron-sized diamond particles as a main reinforcement phase and carbon nanotubes and silicon carbide nanoparticles as auxiliary materials to form a multi-scale reinforcement body, and the surface of the diamond is plated with titanium, so that the interface modified diamond / aluminum-based composite material is obtained. And through the synergistic effect with titanium and boron elements, a continuous and compact titanium carbide interface layer is generated in situ in the preparation process, and the problems that the wettability of an aluminum and diamond interface is poor, and a harmful phase Al4C3 is likely to be generated are effectively solved. The composite material disclosed by the invention has ultrahigh thermal conductivity, low thermal expansion coefficient, high strength and excellent environmental stability, and the prepared insulator hardware has a remarkable advantage of light weight and can meet the harsh requirements of ultrahigh-voltage transmission lines on high reliability, efficient heat dissipation and long service life.

Description

Technical Field

[0001] This invention relates to the field of insulator fitting manufacturing technology, specifically to an interface-modified diamond / aluminum-based composite material, insulator fittings, and their manufacturing process. Background Technology

[0002] Insulator fittings are critical load-bearing and connecting components in high-voltage and ultra-high-voltage transmission lines. Their core function is to ensure the long-term structural integrity and operational reliability of the insulator string while providing mechanical support and electrical connection. The performance of the insulator fitting materials directly determines the safety level, transmission efficiency, and service life of the transmission line.

[0003] Currently, insulator fittings widely used in high-voltage and ultra-high-voltage lines are mostly made of forged cast iron or high-strength aluminum alloy. While forged cast iron is relatively inexpensive and has high strength, it has two inherent drawbacks: first, its high density makes the insulator fittings bulky, placing a significant burden on transportation, installation, and tower load; second, as a magnetic material, it generates significant eddy current losses in alternating magnetic fields, resulting in energy waste and localized overheating, making it unsuitable for modern power grids with increasingly stringent energy-saving requirements. High-strength aluminum alloy achieves lightweight design, but its thermal conductivity is limited, typically below 200 W / (m·K), and its coefficient of thermal expansion is approximately 23 × 10⁻⁶. -6 / K has a thermal expansion coefficient of 5-6×10⁻⁶ with insulator ceramics and glass cores. -6 Severe K mismatch can lead to huge thermal stress at the interface when subjected to current surges or drastic changes in ambient temperature. This can easily cause the brittle core of the insulator to crack, posing a safety hazard.

[0004] To balance the requirements of high thermal conductivity, low expansion, and lightweight design, researchers have turned their attention to metal matrix composites, particularly silicon carbide particle-reinforced aluminum matrix composites. While these materials offer improvements in lightweight design and thermophysical property matching, their overall performance still falls short of meeting the extreme heat dissipation requirements of next-generation ultra-high voltage power transmission lines. Diamond particle-reinforced aluminum matrix composites are considered highly promising next-generation thermal management materials due to their perfect combination of diamond's extremely high thermal conductivity and aluminum's lightweight and easily machinable properties.

[0005] However, molten aluminum exhibits extremely poor wettability with diamond, making effective bonding difficult. Furthermore, during high-temperature preparation, aluminum readily undergoes harmful interfacial reactions with diamond, generating a brittle and easily hydrolyzed Al4C3 phase. This phase rapidly decomposes in humid environments, leading to interfacial failure and a sharp decline in material properties, severely threatening the long-term service safety of the power grid. In addition, existing composite material preparation processes such as pressureless infiltration and powder metallurgy often suffer from incomplete infiltration, high porosity, and uneven reinforcement distribution when used for high-volume-fraction, large-size diamond-reinforced aluminum matrix composites. This makes it difficult to obtain high-performance and uniform parts, limiting their application in structurally and functionally integrated components.

[0006] In view of this, the present invention proposes an interface-modified diamond / aluminum-based composite material and its preparation process. Through multi-scale interface design and controllable composite forming technology, diamond / aluminum-based composite insulator fittings with high thermal conductivity, low coefficient of thermal expansion and environmental stability are prepared. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides, in one aspect, an interface-modified diamond / aluminum-based composite material, insulator fittings, and their preparation process. In the technical solution of this invention, the interface-modified diamond / aluminum-based composite material comprises, by mass percentage:

[0008] High-purity aluminum / aluminum alloy 82%~88%;

[0009] Diamond particles: 8%–12%;

[0010] Carbon nanotubes 3%–5%;

[0011] Silicon carbide nanoparticles: 2%–4%;

[0012] Titanium and boron mixed nanoparticles, 0.5%–1.5%;

[0013] Nano magnesium oxide 1%–2%;

[0014] Rare earth elements 0.5%–1%;

[0015] The diamond particles have a titanium-carbon compound interface layer on their surface, and the composite material has a thermal conductivity of not less than 550 W / (m·K) and a coefficient of thermal expansion of 8-10×10⁻⁶. -6 / K.

[0016] Furthermore, in the technical solution of the present invention, the titanium-carbon compound interface layer is titanium carbide, and its thickness is 50-200 nanometers.

[0017] Furthermore, in the technical solution of the present invention, the titanium carbide interface layer is a crystalline structure, an amorphous structure, or an amorphous / nanocrystalline composite structure.

[0018] Furthermore, in the technical solution of the present invention, the diamond particles are a mixture of multiple particle sizes, including a first diamond particle with a particle size of 80-120μm, a second diamond particle with a particle size of 10-30μm, and a third diamond particle with a particle size of 5-8μm.

[0019] Furthermore, in the technical solution of the present invention, the surface of the carbon nanotubes is coated with an aluminum oxide layer.

[0020] An insulator fitting is manufactured by computer numerical control machining of the aforementioned interface-modified diamond / aluminum-based composite material.

[0021] A process for manufacturing insulator fittings includes the following steps:

[0022] ① A titanium layer with a thickness of 50-150 nanometers is deposited on the surface of diamond particles by chemical vapor deposition to obtain titanium-plated diamond; stearic acid, surfactant and carbon nanotubes are mixed in proportion and ultrasonically dispersed, a precursor of alumina coating is added, and an alumina layer is coated on the surface of dispersed carbon nanotubes by ball milling.

[0023] ② Aluminum powder or aluminum alloy powder, titanium-plated diamond, coated carbon nanotubes, silicon carbide nanopowder, titanium powder, boron powder, nano magnesium oxide and rare earth compound powder are wet ball-milled in proportion to obtain uniform composite powder.

[0024] ③ The composite powder is cold-pressed into a porous preform by cold isostatic pressing;

[0025] The cold isostatic pressing pressure is 200 MPa, the holding time is 5 minutes, and the relative density of the porous preform is 65%–70%.

[0026] ④ Place the preform and aluminum powder particles in a mold, heat to 780-800℃ in a vacuum environment, apply a pressure of 35-40 MPa, hold for 10-15 minutes, and perform high temperature and high pressure treatment to obtain composite material ingot.

[0027] Among them, the vacuum degree throughout the pressing process is ≤1×10 -2 Pa;

[0028] ⑤ The composite material billet is subjected to hot extrusion or hot rolling to obtain a dense composite material;

[0029] ⑥ Using computer numerical control, the insulator fittings are processed to the final dimensions and precision according to the drawings, thus obtaining the required insulator fittings.

[0030] Furthermore, in the technical solution of the present invention, before the high temperature and high pressure treatment in step ④, the temperature is first heated to 655-665℃ in a vacuum environment and kept at that temperature for 3-5 minutes for preheating treatment.

[0031] Effective gain:

[0032] In the technical solution of this invention, the use of aluminum-based composite materials can reduce the weight of fittings by more than 60%, thereby reducing the tower load and simplifying the installation and maintenance process. At the same time, since it is a non-magnetic material, it completely eliminates the eddy current loss of traditional cast iron fittings, and by combining it with multi-scale micron diamond, it reduces the coefficient of thermal expansion of the material, improves the thermal expansion compatibility with the ceramic core of the insulator, and reduces thermal stress cracking.

[0033] Meanwhile, by leveraging the dominant thermal effect of multi-scale micron-diamonds, dispersive strengthening of materials with nano-SiC, and bridging toughening through Al2O3-coated carbon nanotubes, a multi-scale reinforcement system is constructed using materials of different dimensions. This solves the bottleneck problem of single-scale reinforcement, enabling the material to possess both high thermal conductivity and excellent toughness and fatigue resistance, thus meeting the needs of frequent power grid start-ups and shutdowns and load changes.

[0034] Moreover, by combining titanium plating on the diamond surface with titanium / boron dual-element powder doping, a continuous and dense TiC interface layer is formed in situ on the diamond surface, effectively suppressing the formation of the easily hydrolyzable Al4C3 phase. This allows the composite material to maintain a thermal conductivity decay rate of <8% after 1000 hours of aging in a harsh environment of 85℃ / 85% relative humidity, far exceeding that of traditional composite materials, thus extending its service life in harsh environments such as coastal areas and industrial zones.

[0035] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0036] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0037] Figure 1 This is a flowchart illustrating the preparation process of the interface-modified diamond / aluminum-based composite material of the present invention. Detailed Implementation

[0038] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] This invention proposes an interface-modified diamond / aluminum-based composite material, wherein the raw materials comprise, by mass percentage;

[0040] High-purity aluminum / aluminum alloy 82%~88%;

[0041] Diamond particles: 8%–12%;

[0042] Carbon nanotubes 3%–5%;

[0043] Silicon carbide nanoparticles: 2%–4%;

[0044] Titanium and boron mixed nanoparticles, 0.5%–1.5%;

[0045] Nano-sized magnesium oxide 1%–2%;

[0046] Rare earth elements: 0.5%–1%.

[0047] The diamond particles have a titanium-carbon compound interface layer on their surface, and the composite material has a thermal conductivity of not less than 550 W / (m·K) and a coefficient of thermal expansion of 8-10×10⁻⁶. -6 The titanium-carbon compound interface layer is titanium carbide with a thickness of 50-200 nanometers, and preferably, the interface layer is a crystalline structure, an amorphous structure, or an amorphous / nanocrystalline composite structure.

[0048] In this embodiment, the diamond particles are a mixture of multiple particle sizes, including first diamond particles with a particle size of 80-120 μm, second diamond particles with a particle size of 10-30 μm, and third diamond particles with a particle size of 5-8 μm. The diamond particles serve as the core thermally conductive framework, constructing the main thermal conduction pathways within the material. They possess extremely high thermal conductivity, improving the thermal conductivity of the composite material, and the multi-particle-size gradation increases the packing density.

[0049] In this embodiment, the high-purity aluminum alloy / aluminum alloy is spherical particles selected from Jiangsu Boqian New Materials. The aluminum alloy type is 6061 / 6063, with a purity of ≥99.7%. After melting, the high-purity aluminum alloy / aluminum alloy forms a continuous phase, providing plasticity, toughness, and basic thermal conductivity, serving as the basis for material forming and processing.

[0050] In this embodiment, the carbon nanotubes are coated with an alumina layer. Specifically, the carbon nanotubes are multi-walled tubes with a diameter of 20-50 nm and a length of 10-20 μm. As nanoscale reinforcing fibers, the carbon nanotubes bridge the diamond particles and the matrix, improving the material's strength, toughness, and the integrity of the thermal conductivity network.

[0051] In this embodiment, silicon carbide D50 is 50 nm and serves as a dispersion strengthening phase. It pins dislocations through the Orovan mechanism, thereby improving the strength, hardness, and thermal stability of the material. At the same time, it works in conjunction with carbon nanotubes and diamond particles to form a multi-dimensional thermally conductive network to assist in heat conduction.

[0052] In this embodiment, the mass ratio of titanium to boron powder is 1-1.5:1, and the powder particle size is 1-5 μm, serving as an interfacial bonding molecular bridge. Titanium reacts in situ with C on the diamond surface to form a TiC transition layer, enhancing the bonding; boron inhibits the formation of the harmful Al4C3 phase, improving the stability of the material's internal environment.

[0053] In this embodiment, nano-magnesium oxide with a particle size of 30-50 nm serves as a sintering aid, pinning grain boundaries, inhibiting grain growth, and promoting sintering densification. The rare earth element, specifically either Ce or La, purifies the melt, refines grains, optimizes the microstructure, and improves thermal stability and corrosion resistance by forming rare earth intermetallic compounds with impurities.

[0054] In another aspect, the present invention provides an insulator fitting made from the aforementioned interface-modified diamond / aluminum-based composite material.

[0055] This invention also proposes a process for manufacturing insulator fittings, comprising the following steps:

[0056] ① A titanium layer with a thickness of 50-150 nanometers was deposited on the surface of diamond particles by chemical vapor deposition to obtain titanium-plated diamond; stearic acid, 0.1% to 0.3% of surfactant by total volume were mixed with carbon nanotubes in a certain proportion and ultrasonically dispersed, a precursor for alumina coating was added, and an alumina layer was coated on the surface of the dispersed carbon nanotubes by ball milling.

[0057] The ultrasonic power was 800W, the dispersion time was 30min, the ball milling speed was 300-500rpm, and the ball milling time was 30-50min.

[0058] Specifically, the mass ratio of stearic acid to carbon nanotubes is 1-1.5:1; the precursor for the alumina coating is either aluminum isopropoxide or aluminum sec-butoxide. The molar ratio of aluminum ions to carbon nanotubes in the alumina coating precursor is 0.5-1:1. The carbon nanotubes and the alumina coating precursor are ball-milled and mixed, then hydrolyzed and calcined to form an Al2O3 coating.

[0059] In this embodiment, the specific process of coating the carbon nanotube surface with an alumina layer includes:

[0060] Carbon nanotubes, stearic acid, and a surfactant were added together to a beaker containing an appropriate amount of anhydrous ethanol. The beaker was then placed in an ultrasonic disperser and ultrasonically treated at 400–600 W for 30–60 minutes to obtain a uniform black suspension.

[0061] Add the precursor of the alumina coating layer in the appropriate proportion to the above suspension and stir magnetically until completely dissolved to obtain a mixed slurry.

[0062] The mixed slurry was transferred to a ball mill jar with a ball-to-material ratio of 10-20:1 and a rotation speed of 300-400 rpm. The mixture was then ball-milled for 6-12 hours in a sealed environment. During the ball milling process, the precursor of the alumina coating layer underwent a slow sol-gel reaction with moisture in the air, generating amorphous aluminum hydroxide, which was then uniformly coated onto the surface of the carbon nanotubes under the mechanical force of the ball mill.

[0063] After ball milling, the filter cake was washed repeatedly with anhydrous ethanol to remove excess stearic acid, surfactants and reaction byproducts. The filter cake was then dried in a vacuum drying oven at 60-80℃ for 12 hours to obtain Al2O3 precursor coated carbon nanotubes.

[0064] The dried Al2O3 precursor coated carbon nanotubes are placed in a muffle furnace or tube furnace and heated to 450-500℃ at a rate of 2-5℃ / min under an air or oxygen atmosphere, and held at that temperature for 2 hours to obtain carbon nanotubes with an alumina coating on the surface.

[0065] Understandably, during the sintering process, stearic acid and surfactants are completely decomposed and burned off at 300-400℃, and amorphous aluminum hydroxide is transformed into crystalline γ-Al2O3, forming a strong and dense protective layer on the surface of carbon nanotubes.

[0066] ② Aluminum powder or aluminum alloy powder, titanium-plated diamond, coated carbon nanotubes, silicon carbide nanopowder, titanium powder, boron powder, nano magnesium oxide and rare earth compound powder are wet ball-milled in proportion to obtain uniform composite powder.

[0067] The process involved using ethanol as the medium, a ball-to-material ratio of 5:1, a rotation speed of 300 rpm, and a time of 12–18 hours.

[0068] ③ The composite powder is cold-pressed into a porous preform by cold isostatic pressing;

[0069] The pressure is 200 MPa, and the pressure is held for 5 minutes. The relative density of the porous preform is 65% to 70%.

[0070] Understandably, the preform provides a continuous and stable pore channel for subsequent aluminum liquid infiltration and fixes the position of the reinforcing phase particles to prevent drift.

[0071] ④ Place the preform and aluminum powder particles in a mold, heat to 655-665℃ in a vacuum environment, hold for 3-5 minutes, then raise the temperature to 780-800℃ and apply a pressure of 35-40 MPa, hold for 10-15 minutes, so that the molten aluminum liquid permeates the preform. During this period, the titanium layer on the diamond surface reacts with carbon atoms in situ to generate a titanium-carbon compound interface layer, and finally obtains the composite material ingot.

[0072] Among them, the vacuum degree is ≤1×10 -2 Pa;

[0073] Understandably, when aluminum melts into a liquid state, Ti reacts with C atoms on the diamond surface to form a TiC interface layer. Furthermore, the Ti layer deposited on the diamond surface undergoes in-situ interface reactions at specific points and in specific quantities on each diamond surface. Ti powder acts as a global supplement and system purifier, repairing potentially damaged interfaces and thermodynamically inhibiting harmful phases. Botanical diffusion inhibits Al4C3 formation. Under high pressure, the molten aluminum completely fills the pores of the preform through infiltration, resulting in a high-density composite material ingot.

[0074] ⑤ The composite material billet is subjected to hot extrusion or hot rolling to obtain a dense composite material;

[0075] The heat treatment temperature is 450-500℃, the extrusion ratio is 10:1, and the internal micropores of the weld are treated; the sintered neck is broken to form a directional fiber texture, thereby improving the uniformity of the longitudinal mechanical properties and thermal conductivity of the material.

[0076] ⑥ Through computer numerical control (CNC) machining, according to the drawing requirements of the insulator fittings (such as flanges and ball heads), the fittings are machined to the final size and accuracy to obtain the required insulator fittings.

[0077] To further understand the present invention, the insulator fittings provided by the present invention will be described below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0078] Example 1

[0079] Preparation of carbon nanotubes coated with an alumina layer:

[0080] 1g of carbon nanotubes, 1.5g of stearic acid, and 0.3% of surfactant were added to a beaker containing 200ml of anhydrous ethanol. The beaker was placed in an ultrasonic disperser and ultrasonicated at 400W for 30 minutes to obtain a uniform black suspension.

[0081] Add 12.8g of aluminum isopropoxide to the above suspension and stir magnetically until completely dissolved to obtain a mixed slurry.

[0082] The mixed slurry was transferred to a ball mill jar with a ball-to-material ratio of 10:1 and a rotation speed of 300 rpm. The mixture was then ball-milled for 6 hours in a sealed environment.

[0083] After ball milling, the filter cake was washed repeatedly by vacuum filtration with anhydrous ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain Al2O3 precursor coated carbon nanotubes.

[0084] The dried Al2O3 precursor coated carbon nanotubes are placed in a muffle furnace or tube furnace and heated to 450°C at a rate of 2°C / min under air atmosphere, and held for 2 hours to obtain carbon nanotubes with an alumina coating.

[0085] Example 2

[0086] Preparation of interface-modified diamond / aluminum matrix composites:

[0087] ① A titanium-plated diamond is obtained by coating a 50-nanometer-thick titanium layer onto the surface of diamond particles using chemical vapor deposition.

[0088] ② 84% aluminum powder, 8% titanium-plated diamond, 3% coated carbon nanotubes prepared in Example 1, 2% silicon carbide nanoparticles, 1% titanium powder, 0.5% boron powder, 1% nano magnesium oxide and 0.5% Ce powder were wet-milled for 12 hours at 300 rpm with ethanol as medium and a ball-to-material ratio of 5:1 to obtain a uniform composite powder.

[0089] ③The composite powder is cold-pressed into a porous preform by applying a cold isostatic pressure of 200 MPa and holding it for 5 minutes.

[0090] ④ Place the preform and aluminum source in the mold, and ensure a vacuum degree ≤ 1×10 -2 Heating to 655℃ under Pa environment, holding for 3 minutes, then raising the temperature to 800℃ and applying a pressure of 40 MPa, holding for 15 minutes, yields composite material billet.

[0091] ⑤ The composite material billet is hot-rolled at a heat treatment temperature of 450℃ and an extrusion ratio of 10:1 to obtain a dense composite material.

[0092] ⑥ The insulator fittings are manufactured by computer numerical control according to the requirements of the insulator fitting flange drawings.

[0093] Example 3

[0094] ① A titanium-plated diamond is obtained by coating a 150-nanometer-thick titanium layer onto the surface of diamond particles using chemical vapor deposition.

[0095] ② 82.5% aluminum alloy, 10% titanium-plated diamond, 3% coated carbon nanotubes prepared in Example 1, 2% silicon carbide nanopowder, 0.5% titanium powder, 0.25% boron powder, 1% nano magnesium oxide and 0.75% La powder were wet ball-milled at 400 rpm for 16 hours with ethanol as medium and ball-to-material ratio of 10:1 to obtain a uniform composite powder.

[0096] ③The composite powder is cold-pressed into a porous preform by applying a cold isostatic pressure of 200 MPa and holding it for 5 minutes.

[0097] ④ Place the preform and aluminum source in the mold, and ensure a vacuum degree ≤ 1×10 -2 Heating to 665℃ under Pa environment, holding for 5 minutes, then raising the temperature to 780℃ and applying a pressure of 35 MPa, holding for 10 minutes, yields composite material billet.

[0098] ⑤ The composite material billet is hot-rolled at a heat treatment temperature of 450℃ and an extrusion ratio of 10:1 to obtain a dense composite material.

[0099] ⑥ The insulator fittings are manufactured by computer numerical control according to the requirements of the insulator fitting flange drawings.

[0100] Example 4

[0101] ① A titanium-plated diamond is obtained by coating a 100-nanometer-thick titanium layer onto the surface of diamond particles using chemical vapor deposition.

[0102] ② 82.5% aluminum alloy, 10% titanium-plated diamond, 3% coated carbon nanotubes prepared in Example 1, 2% silicon carbide nanopowder, 0.5% titanium powder, 0.25% boron powder, 1% nano magnesium oxide and 0.75% La powder were wet ball-milled at 400 rpm for 16 hours with ethanol as medium and ball-to-material ratio of 10:1 to obtain a uniform composite powder.

[0103] ③The composite powder is cold-pressed into a porous preform by applying a cold isostatic pressure of 200 MPa and holding it for 5 minutes.

[0104] ④ Place the preform and aluminum source in the mold, and ensure a vacuum degree ≤ 1×10 -2 Heating to 665℃ under Pa environment, holding for 5 minutes, then raising the temperature to 790℃ and applying a pressure of 35 MPa, holding for 10 minutes, yields a composite material billet.

[0105] ⑤ The composite material billet is hot-rolled at a heat treatment temperature of 450℃ and an extrusion ratio of 10:1 to obtain a dense composite material.

[0106] ⑥ The insulator fittings are manufactured by computer numerical control according to the requirements of the insulator fitting flange drawings.

[0107] Comparative Example 1

[0108] The commercially available insulator fitting flange is from Nanjing Electric, model WS-16.

[0109] Comparative Example 2

[0110] ① 82.5% aluminum alloy, 10% diamond, 3% coated carbon nanotubes prepared in Example 1, 2% silicon carbide nanopowder, 0.5% titanium powder, 0.25% boron powder, 1% nano magnesium oxide and 0.75% La powder were wet ball-milled for 16 hours at 400 rpm with ethanol as medium and ball-to-material ratio of 10:1 to obtain a uniform composite powder.

[0111] ②The composite powder is cold-pressed into a porous preform by applying a cold isostatic pressure of 200 MPa and holding it for 5 minutes.

[0112] ③ Place the preform and aluminum source in the mold, and apply pressure at a vacuum level ≤ 1×10⁻⁶. -2 Heating to 665℃ under Pa environment, holding for 5 minutes, then raising the temperature to 800℃ and applying a pressure of 35 MPa, holding for 10 minutes, yields composite material billet.

[0113] ④ The composite material billet is hot-rolled at a heat treatment temperature of 450℃ and an extrusion ratio of 10:1 to obtain a dense composite material.

[0114] ⑤ The insulator fittings are manufactured by computer numerical control according to the requirements of the insulator fitting flange drawings;

[0115] Comparative Example 3

[0116] ① A titanium-plated diamond is obtained by coating a 150-nanometer-thick titanium layer onto the surface of diamond particles using chemical vapor deposition.

[0117] ② 82.5% aluminum alloy, 10% titanium-plated diamond, 3% coated carbon nanotubes prepared in Example 1, 2% silicon carbide nanopowder, 0.75% boron powder, 1% nano magnesium oxide and 0.75% La powder were wet-milled for 16 hours at 400 rpm with ethanol as medium and a ball-to-material ratio of 10:1 to obtain a uniform composite powder.

[0118] ③The composite powder is cold-pressed into a porous preform by applying a cold isostatic pressure of 200 MPa and holding it for 5 minutes.

[0119] ④ Place the preform and aluminum source in the mold, and ensure a vacuum degree ≤ 1×10 -2Heating to 665℃ under Pa environment, holding for 5 minutes, then raising the temperature to 800℃ and applying a pressure of 35 MPa, holding for 10 minutes, yields composite material billet.

[0120] ⑤ The composite material billet is hot-rolled at a heat treatment temperature of 450℃ and an extrusion ratio of 10:1 to obtain a dense composite material.

[0121] ⑥ The insulator fittings are manufactured by computer numerical control according to the requirements of the insulator fitting flange drawings.

[0122] Comparative Example 4

[0123] ① A titanium-plated diamond is obtained by coating a 150-nanometer-thick titanium layer onto the surface of diamond particles using chemical vapor deposition.

[0124] ② 82.5% aluminum alloy, 10% titanium-plated diamond, 3% coated carbon nanotubes prepared in Example 1, 2% silicon carbide nanopowder, 0.25% boron powder, 1% nano magnesium oxide and 0.75% La powder were wet ball-milled at 400 rpm for 16 hours with ethanol as medium and ball-to-material ratio of 10:1 to obtain a uniform composite powder.

[0125] ③The composite powder is cold-pressed into a porous preform by applying a cold isostatic pressure of 200 MPa and holding it for 5 minutes.

[0126] ④ Place the preform and aluminum source in the mold, and ensure a vacuum degree ≤ 1×10 -2 Heating to 665℃ under Pa environment, holding for 5 minutes, then raising the temperature to 800℃ and applying a pressure of 35 MPa, holding for 10 minutes, yields composite material billet.

[0127] ⑤ The composite material billet is hot-rolled at a heat treatment temperature of 450℃ and an extrusion ratio of 10:1 to obtain a dense composite material.

[0128] ⑥ The insulator fittings are manufactured by computer numerical control according to the requirements of the insulator fitting flange drawings.

[0129] Test example:

[0130] The contact thermal conductivity of the materials and insulator fittings in Examples 2 and 3 and Comparative Examples 1 to 4 was tested according to GB / T 22588-2008 standard. The specific results are shown in Table 1.

[0131] The coefficient of thermal expansion of the materials and insulator fittings in Examples 2 and 3 and Comparative Examples 1 to 4 were tested according to GB / T 4339-2008 standard. The specific results are shown in Table 1.

[0132] Density tests were performed on the materials and insulator fittings in Examples 2 and 3, and Comparative Examples 1 to 4, according to ASTM B311 standard. The specific results are shown in Table 1.

[0133] Bending strength / modulus tests were performed on the materials and insulator fittings in Examples 2 and 3 and Comparative Examples 1 to 4 according to ASTM C1161 standard. The specific results are shown in Table 1.

[0134] According to GB / T 4056-2008 standard, destructive load tests were conducted on the materials and insulator fittings in Examples 2 and 3 and Comparative Examples 1 to 4. The specific results are shown in Table 1.

[0135] Temperature rise tests were conducted on the materials and insulator fittings in Examples 2 and 3 and Comparative Examples 1 to 4 according to the IEEE Std 1043 standard. The specific results are shown in Table 1.

[0136] Thermal shock tests were conducted on the materials and insulator fittings in Examples 2 and 3 and Comparative Examples 1 to 4 according to IEC 61109 standard. The specific results are shown in Table 1.

[0137] Accelerated aging tests were conducted on the materials and insulator fittings in Examples 2 and 3 and Comparative Examples 1 to 4 according to the Double 85 test standard. The specific results are shown in Table 1.

[0138]

[0139] In summary, this invention provides an interface-modified diamond / aluminum-based composite material, insulator fittings, and their preparation process. By using an aluminum-based composite material, the material density is approximately 3.0 g / cm³. 3 This reduces tower load and simplifies installation and maintenance. Furthermore, the non-magnetic material completely eliminates eddy current losses associated with traditional cast iron fittings, and the combination with multi-scale micron-sized diamond reduces the material's coefficient of thermal expansion to 8-10 × 10⁻⁶. -6 / K improves the thermal expansion compatibility with the ceramic core of the insulator and reduces thermal stress cracking.

[0140] Meanwhile, accelerated aging tests show that by combining titanium plating on the diamond surface with titanium / boron dual-element powder doping, a continuous and dense TiC interface layer is formed in situ on the diamond surface, which can effectively suppress the formation of easily hydrolyzable phase Al4C3. This results in the composite material having a thermal conductivity decay rate of <8% after 1000 hours of aging in a harsh environment of 85℃ / 85% relative humidity.

[0141] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An interface-modified diamond / aluminum-based composite material, characterized in that, Raw materials, by weight percentage, include: High-purity aluminum / aluminum alloy 82%~88%; Diamond particles: 8%–12%; Carbon nanotubes 3%–5%; Silicon carbide nanoparticles: 2%–4%; Titanium and boron mixed nanoparticles, 0.5%–1.5%; Nano magnesium oxide 1%–2%; Rare earth elements 0.5%–1%; The diamond particle surface is constructed with a titanium-carbon compound interface layer formed by in-situ reaction, and the thermal conductivity of the composite material is not less than 550 W / (m*K), and the thermal expansion coefficient is 8-10*10 -6 / K.

2. The interface-modified diamond / aluminum-based composite material according to claim 1, characterized in that, The titanium-carbon compound interface layer is specifically titanium carbide, with a thickness of 50-200 nm.

3. The interface-modified diamond / aluminum-based composite material according to claim 2, characterized in that, The titanium carbide interface layer has a crystalline structure, an amorphous structure, or an amorphous / nanocrystalline composite structure.

4. The interface-modified diamond / aluminum-based composite material according to claim 1, characterized in that, The diamond particles are a mixture of multiple particle sizes, including a first diamond particle with a particle size of 80-120μm, a second diamond particle with a particle size of 10-30μm, and a third diamond particle with a particle size of 5-8μm.

5. The interface-modified diamond / aluminum-based composite material according to claim 1, characterized in that, The carbon nanotubes are coated with an aluminum oxide layer.

6. A method for preparing the composite material as described in any one of claims 1 to 5, characterized in that, Includes the following steps: ① A titanium layer with a thickness of 50-150 nanometers is deposited on the surface of diamond particles by chemical vapor deposition to obtain titanium-plated diamond; stearic acid, surfactant and carbon nanotubes are mixed in proportion and ultrasonically dispersed, a precursor of alumina coating is added, and an alumina layer is coated on the surface of dispersed carbon nanotubes by ball milling. ② Aluminum powder or aluminum alloy powder, titanium-plated diamond, alumina-coated carbon nanotubes, silicon carbide nanoparticles, titanium powder, boron powder, nano magnesium oxide and rare earth compound powder are wet ball-milled in proportion to obtain a uniform composite powder. ③ The composite powder is cold-pressed into a porous preform by cold isostatic pressing; The cold isostatic pressing pressure is 200 MPa, the holding time is 5 minutes, and the relative density of the porous preform is 65%–70%. ④ Place the preform and aluminum source in a mold, heat to 780-800℃ in a vacuum environment, apply a pressure of 35-40 MPa, hold for 10-15 minutes, and perform high temperature and high pressure treatment to obtain composite material billet. In the whole pressing process, the vacuum degree is less than or equal to 1x10 -2 Pa. ⑤ The composite material billet is subjected to hot extrusion or hot rolling to obtain a dense composite material.

7. The method for preparing composite materials according to claim 6, characterized in that, Before the high-temperature and high-pressure treatment in step ④, a preheating treatment is also performed in a vacuum environment at a temperature of 655-665℃ for 3-5 minutes.

8. An insulator fitting, characterized in that, It is made by precision machining of the interface-modified diamond / aluminum matrix composite material as described in any one of claims 1-5.

9. A manufacturing process for insulator fittings, characterized in that, The composite material is prepared using the method described in claim 6 or 7, and then machined to form the insulator fitting.

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