1071 results about "Melting point" patented technology

The invention discloses a high-strength silver-free copper-based brazing filler metal which is composed of P, Sn, Ni and Cu. The high-strength silver-free copper-based brazing filler metal is low in cost, safe, environmentally friendly and good in welding effect; through the adding of Sn and Ni, the melting point of brazing filler metal alloy is reduced, and the tensile strength and wettability of the brazing filler metal alloy are enhanced.

The invention provides a long glass fiber reinforced flame-retardant ceramic polypropylene material and a preparation method thereof. Comprising the following components in parts by weight: 0-20 parts of polypropylene, 30-60 parts of flame-retardant long glass fiber master batch and 40-70 parts of ceramic master batch. According to the invention, the multi-gradient melting point glass powder, the phosphorus flame retardant, the tetrapod-like zinc oxide whisker, the long glass fiber and the ceramic forming filler are matched, so that a carbon layer can be kept compact in structure and high in structural strength during combustion, resists flame pressure and is not damaged; an interlayer structure blocks a heat conduction path, the back surface temperature is obviously reduced, and the material is prevented from softening and collapsing. The obvious effects of ablation resistance, good processing, high strength, good flame retardance, low cost and light weight are achieved.

The present invention discloses a medium-high performance neodymium iron boron and a preparation method thereof. Through the master-slave phase double alloy process, the master phase alloy is cerium iron boron with a low total rare earth content, and the slave phase is a neodymium iron boron alloy with a high total rare earth content, avoiding the entry of light rare earths in the master phase into the grain boundaries, while the surplus rare earths in the slave phase enter the grain boundaries and are recombined into rare earth-rich phases. The prepared magnet is processed into a thin magnetic sheet, and a low-melting-point HReM alloy is magnetron sputtered, realizing low-temperature grain boundary diffusion. This alloy improves the grain boundary wettability and also improves the fluidity of the rare earth-rich phase, enabling the cerium-containing neodymium iron boron master and slave phase grains to be quickly isolated during grain boundary diffusion. The low-temperature diffusion avoids the replacement of the diffused heavy rare earths by praseodymium, neodymium, and cerium elements, inhibits the exchange coupling between cerium iron boron grains, and makes the heavy rare earths free in the grain boundaries or interact with the rare earth-rich phase to form a core-shell structure on the surface layer of the master phase grains, enabling the rare earth-rich phase to be continuously and uniformly distributed, effectively enhancing the effectiveness of the grain boundary diffusion of heavy rare earth elements in improving the intrinsic coercivity of the cerium-containing magnet.

The invention discloses a method for purifying electronic-grade hafnium tetrachloride, which comprises the following steps of: removing insoluble substances by adopting an organic solvent matched with hafnium tetrachloride, removing low-melting-point impurities through low-temperature boiling, removing high-melting-point impurities through high-temperature sublimation, and removing substances with different chemical properties and polarities through a complexing and decomplexing method. And finally, sublimating to further remove impurities to finally obtain the electronic-grade hafnium tetrachloride with the purity not lower than 7N grade. The method has the characteristics of good purification effect, multi-method comprehensive impurity removal, industrial large-scale application, stable quality, high yield and simple and easy-to-separate impurity components.

The invention relates to a diffusion source for a neodymium-iron-boron magnet and a preparation method and application of the diffusion source. The invention discloses a rare-earth metal catalyst which comprises the following components in percentage by mass: 46%-49% of an organic solvent, 0.1%-2% of an adhesive, 0.1%-5% of a metal oxide and 46%-49% of rare-earth metal, and the melting point of the metal oxide is higher than that of the neodymium-iron-boron magnet. The specific organic solvent, the adhesive, the metal oxide and the rare earth metal are matched for use according to a specific matching relation, so that the diffusion source is more stable, the diffusion effect is improved, and when the magnet attached with the diffusion source is subjected to thermal diffusion treatment, the rare earth metal can be diffused into the magnet so as to improve the coercive force and other properties of the magnet. In the process, the high-melting-point metal oxide is adhered to the surface of the magnet and then serves as a spacer, the adhesion phenomenon of the magnet in the high-temperature sintering diffusion process is reduced or avoided, grain boundary diffusion is further promoted, and the performance of the magnet is improved.

A latent heat storage particle that comprises a core particle and a coating part covering at least a part of the surface of the core particle, wherein: the core particle is composed of an element selected from the group consisting of Al, Mg, Si, Ti, Fe, Ni, Cu, Zn, Sn, Sb, Ga, In, Bi, Pb and Cd or an alloy or a compound mainly composed of the same and has a melting point of 100° C. or higher; the coating part is composed of one or more selected from the group consisting of an element different from the component of the core particle, an alloy and an inorganic compound containing the element and a mixture thereof, which does not undergo a chemical reaction with the core particle in the temperature range of the operating temperature; and at least a part of the coating part is in a particulate shape.

The invention relates to the field of co-extrusion production control, and particularly discloses an efficient film bag feeding control system, which is applied to a multi-raw-material synchronous conveying device of a co-extrusion process, and comprises a full-link data acquisition module, a full-link data processing module and a full-link data processing module, the raw material characteristic parameters comprise a melting point T, a stacking density rho and a magnetic sensitive particle loading amount M; the instantaneous load pressure P of each raw material conveying channel, the temperature Tm of a co-extrusion die head melting area, the real-time thickness H of a co-extrusion film layer, stock bin liquid level data and motor rotating speed data are collected and integrated to obtain a full-link original data set; the single-drive linkage conveying mechanism comprises a main servo motor, a plurality of sets of electromagnetic clutches and a plurality of sets of spiral conveying assemblies, and the main servo motor drives a transmission shaft through a synchronous belt. According to the technical scheme, for the co-extrusion process, the multi-raw-material synchronous conveying precision can be matched, and the problems that parameter adjustment lags behind, adaptability is poor and a downstream process feedback closed loop is lacked are solved.

The invention discloses a crystallization process of o-chloro-p-nitroaniline, which comprises the following steps: feeding a material into a crystallization kettle to crystallize the o-chloro-p-nitroaniline, regulating and controlling the temperature in the kettle body in the crystallization process, cooling to a metastable region of the o-chloro-p-nitroaniline, preserving the heat in the metastable region for a first preset time length, and then cooling to a second preset time length; continuously cooling to a first temperature lower than the melting point of the o-chloro-p-nitroaniline, keeping the temperature at the first temperature for a second preset duration, continuously cooling to a second temperature, and outputting the material out of the crystallization kettle for filtration and separation; in the cooling process, the cooling speed in the kettle body is controlled to be 0.1-0.2 DEG C / min. According to the invention, the interior of the kettle body can be slowly cooled, and the cooling speed of each part in the kettle body can be more uniform, so that the crystallization purity and the product quality of o-chloro-p-nitroaniline are finally improved.

The invention discloses a preparation method of a high-strength, high-hardness and ablation-resistant CuWTaTeAl gradient nano composite material. The method comprises the following steps: 1, mechanically mixing Cu80Al20 spherical coated powder, Cu90W10 spherical coated powder, WTe2 alloy powder, Ta powder and Cu powder, and then carrying out ball milling and mixing; 2, performing SPS (spark plasma sintering); thirdly, after soaking treatment, multi-pass hot rolling deformation is carried out, and then quenching treatment is carried out; and 4, annealing heat treatment. The binary spherical coating powder, the alloy powder and the elementary substance powder are subjected to ball milling and mixing to achieve uniform distribution of all elements, high-melting-point W and Ta are added to improve the ablation-resistant temperature of the composite material, large-scale copper dendrite powder is added to form gradient distribution nanocrystals, the proportion of all the elements is controlled, the lattice distortion degree is increased, and the ablation-resistant temperature of the composite material is improved. The high-strength, high-hardness and ablation-resistant CuWTaTeAl gradient nano composite material is suitable for the fields of contacts, switches, electrical connectors, resistance welding electrodes and the like.

The invention relates to the technical field of ceramic material repairing, in particular to a one-time sintering repairing method for reactive sintering silicon carbide material defects. Comprising the following steps: measuring the defect size of reactive sintering silicon carbide, and cutting a silicon-based alloy block slightly larger than the defect size; carrying out ultrasonic cleaning on the defect part of the reactive sintering silicon carbide by adopting an organic solvent, wherein the ultrasonic time is 20-40 minutes; placing the silicon-aluminum alloy block above the defect of the reactive sintering silicon carbide, and uniformly paving silicon powder on the surface of the reactive sintering silicon carbide; the mass fraction of the silicon powder is 3-8% of that of the reactive sintering silicon carbide; setting a proper sintering temperature, heating according to a heating rate of 3-10 DEG C / min, and keeping the temperature for 1-3 hours after the sintering temperature is reached; the sintering temperature is higher than the melting point of the silicon-based alloy; and polishing the surface of the repaired reactive sintering silicon carbide to obtain the repaired reactive sintering silicon carbide. The method has the advantages that low-porosity and high-density repair of the crack area is guaranteed, and the optical performance of the reflector is not reduced.

A coke product configured to be used in foundry cupolas to melt iron and produce cast iron products is disclosed herein. In some embodiments, the coke product has a Coke Reactivity Index (CRI) of at least 30% and an ash fusion temperature (A FT) less than 1316° C. Additionally or alternatively, the coke product can comprise a fixed carbon content of at least 80% and / or a volatile matter content of no more than 1.0%.

The invention relates to the technical field of molten salt, in particular to nitro binary molten salt and a preparation method thereof. The preparation method comprises the following steps: mixing sodium carbonate and a potassium hydroxide solution, and then adding a starch-based grafted crystal inhibitor to inhibit crystallization; adding a nitric acid aqueous solution in two stages, and introducing eutectic seed crystals to guide nucleation at the end of the first stage; crystal distribution is optimized through falling film evaporation and concentration and setting of partial reflux; and after spraying granulation, carrying out short-time melting reforming and controlled cooling in an inert atmosphere. According to the method, the composition uniformity and the structural stability of the molten salt are remarkably improved, so that the product has a melting point close to a theoretical eutectic point, low supercooling degree, high melting latent heat and excellent thermal cycling stability and corrosion resistance, and is suitable for an industrial heat storage system running for a long time.

In a first step S101, the raw material is directly induction heated using a high-frequency induction heating coil (103) while cooling the outer periphery of a raw material (151) to or below the melting point of the raw material by a cooling mechanism (102) to form a raw material melt (152) (raw material melting step). In a second step S102, a seed crystal (161) is brought into contact with the melt (seeding step). In a third step S103, a crystal (153) is grown from the seed crystal (crystal growth step). In the third step S103, the high-frequency induction heating coil and the seed crystal are gradually separated from each other while maintaining the relative distance between the high-frequency induction heating coil and the outer periphery of the raw material, and the crystal is grown in the melt.

The invention relates to the field of furnace lining materials, in particular to a rapid repairing material for a tapping hole and a furnace lining of an intermediate frequency furnace. The rapid repairing material comprises the following components in parts by weight: 50-70 parts of tabular corundum, 10-20 parts of fused magnesite, 8-15 parts of alumina micro powder, 3-8 parts of nano zirconia, 5-12 parts of silicon carbide, 10-15 parts of silica sol and 2-5 parts of a reinforcing agent. Wherein the reinforcing agent is titanium calcium aluminate coated with chromium nickel boride. The tabular corundum is mainly used as an integral framework; the fused magnesite is matched with the alumina micro powder to form magnesium aluminate spinel with a high melting point; the nano zirconium oxide can fill pores and is excellent in toughness; the silicon carbide has the advantages of high hardness, high thermal conductivity and high melting point; the reinforcing agent is titanium calcium aluminate coated with chromium nickel boride, although the adding amount is small, the high-temperature strength, toughness and thermal shock resistance of the repairing material can be remarkably improved, and especially the long-term corrosion resistance can be remarkably improved.

The invention discloses a multi-material plastic plate extrusion molding device which comprises a plurality of double-screw extruders, the output ends of the double-screw extruders are communicated with a conveying pipe, and the end, away from the double-screw extruders, of the conveying pipe is communicated with a conveying shell. The invention relates to the technical field of plastic plate production equipment, through cooperation of the double-screw extruder, the conveying pipe, the conveying shell, the mixing and conveying assembly and the extrusion shaping assembly, extrusion shaping of multi-material plastic plates is achieved, targeted temperature and rotating speed setting can be conducted according to the characteristics of different raw materials, and the production efficiency is improved. Different raw materials are mixed in an optimal molten state, the problems of layering, uneven mixing and the like caused by large differences of melting points and flowability in the mixing process of the different materials are avoided, the overall stability and reliability of the plastic plate are improved, the requirements of the market for the multi-material composite plastic plate are met, and the market prospect is wide. The large-scale application of the plastic plate in more fields is promoted.

The invention relates to thermal fatigue resistant ceramic and a production process thereof, and belongs to the technical field of ceramic material preparation, the thermal fatigue resistant ceramic comprises the following raw materials by mass: 90-100 parts of a base material, 5-10 parts of a flexibilizer, 1-3 parts of a sintering aid and 1-3 parts of an additive; wherein the base material is obtained by mixing calcium carbonate, talc, aluminum oxide, kaolin and a nano zirconium oxide precursor according to the mass ratio of (0.75-1.25): (2-3): (80-85): (3-4): (3-4). The base material in the thermal fatigue-resistant ceramic selects the aluminum oxide as a main component, and the aluminum oxide has extremely high melting point and hardness and excellent chemical stability, so that the ceramic can keep stable physical and chemical properties in a high-temperature environment, and the thermal fatigue resistance of the ceramic is remarkably enhanced.

According to the low-temperature separation and enrichment system and method for the elements in the multi-element complex metallurgical material, the multi-element complex metallurgical material is pretreated to form powder with a certain particle size, the powder is mixed with pulverized coal and subjected to a reduction reaction with hydrogen in a reaction chamber, meanwhile, different valuable metal elements are separated and enriched through the difference between melting points and boiling points, and the elements in the multi-element complex metallurgical material are separated and enriched. The method not only realizes efficient separation and recovery of elements such as iron, lead, zinc, potassium and sodium in the multi-element complex metallurgical material, but also solves the problems of high energy consumption, low reduction rate and the like in the reduction process of the multi-element complex metallurgical material, and has the advantages of short flow, less equipment, safety in operation, economy, high efficiency and easiness in industrial large-scale production.

To provide a multi-layer biaxially oriented film that is resistant to tearing and the like even when stretched at high ratios, and that exhibits excellent heat resistance, particularly heat seal resistance (low shrinkage during heat sealing).SOLUTION: A multi-layer biaxially oriented film comprises an A layer and a B layer, wherein the A layer comprises: a resin composition comprising 75-99 mass% of a polymer satisfying (I) to (II); and 1-25 mass% of a copolymer satisfying (III) to (IV). (I): A content of a constituent unit derived from 4-methyl-1-pentene is 90.0-100 mol%, and a content of a constituent unit derived from a C3-20 α-olefin other than 4-methyl-1-pentene is 0.0 to 10.0 mol%. (II): A melting point is 200-250°C. (III): A content of a constituent unit derived from 4-methyl-1-pentene is 65.0-96.0 mol%, and a content of a constituent unit derived from a C8-20 α-olefin is 4.0 to 35.0 mol%. (IV): A melting point is not observed or is 100 to 199°C.SELECTED DRAWING: None

The invention discloses a method for preparing a transdermal microneedle based on gallium-based liquid metal, which comprises the following steps: (1) heating the gallium-based liquid metal at a temperature higher than the melting point of the liquid metal, so that the gallium-based liquid metal is completely molten into a liquid state; (2) sucking the liquid metal preheated in the step (1) by using a microsyringe or a pipettor, and quickly injecting the liquid metal into a microneedle mold, so that the liquid metal is spread and completely covers a cavity of a needle tip in the mold; (3) transferring the mold in the step (2) into a constant-temperature vacuum box, and decompressing and degassing under vacuum; in the degassing process, the degassing temperature enables the liquid metal to be kept in a flowing liquid state all the time, and vacuumizing is conducted till the pressure is not higher than 10 Pa; the degassing time is not less than 5 hours; (4) continuously injecting the preheated gallium-based liquid metal or a degradable polymer solution into the mold to form a substrate of the microneedle; and (5) transferring the mold in the step (4) to a temperature far lower than the melting point of the liquid metal, and freezing and forming to obtain the transdermal microneedle.

The invention relates to the technical field of computational material science, in particular to a high-entropy ceramic phase change strengthened silver-based electric contact material component screening method, which comprises the following steps of: firstly, based on first principle calculation and Monte Carlo molecular dynamics simulation, combining experimental data correction, and screening out a (MgCoNiCuZn) O component proportion of which the phase change temperature is close to a silver melting point and the single-phase enthalpy value is high; secondly, dynamically simulating wetting behaviors of liquid silver and O with different component proportions (MgCoNiCuZn) through molecular dynamics, and selecting a component proportion with the best wettability with the liquid silver in combination with phase boundary energy calculation and wetting angle experimental verification; and finally, preparing a sample based on spark plasma sintering, actually measuring a wetting angle by using a seat drop method, and feeding back and correcting simulation parameters to form closed-loop optimization. The method is suitable for wettability collaborative optimization screening of a rare earth element doped high-entropy oxide system and liquid metal, proper components can be efficiently and accurately screened out, and the performance of the silver-based electric contact material is improved.

The invention relates to the technical field of refractory materials, in particular to an antioxidant and application thereof in steel ladle slag line bricks, and the antioxidant comprises a Si / SiC multiphase material, modified nano Al2O3 and CaF2; the ladle slag line brick comprises an antioxidant, fused magnesite, crystalline flake graphite and phenolic resin. Si-SiC compound waste is subjected to magnetic separation and acid pickling, then a SiO2 passivation layer is formed through pre-oxidation, moisture and air in the storage period are isolated, and a titanate coupling agent is introduced to improve the wettability and compatibility with phenolic resin. P2O5 released by phosphate on the surface of the modified nano Al2O3 at a high temperature reacts with alkali (earth) metal migrated to a SiO2 oxide layer to prevent the alkali (earth) metal from forming a low-melting-point eutectic substance, CaF2 reacts with SiO2 along with temperature rise, a passivation layer is broken, internal Si and SiC are directly exposed, and boron oxide of the modified nano Al2O3 remarkably reduces activation energy and a temperature threshold value of the reaction of CaF2 and SiO2.

The invention relates to a high-purity high-temperature alloy and a preparation method thereof, and belongs to the technical field of high-temperature alloys. The preparation method comprises the following steps: proportioning and melting: proportioning by using a Ni-Cr-Nb intermediate alloy; wherein the oxygen content and the nitrogen content are both smaller than 100 ppm; the melting point is below 1250 DEG C; in the refining stage, after the raw materials are completely melted, the temperature is gradually increased to the refining temperature of 1490-1510 DEG C, and then the refining stage is started; in the refining process, the vacuum degree is kept to be smaller than or equal to 1 Pa; the tapping temperature is adjusted to 1440 DEG C to 1460 DEG C, electrified pouring is carried out under the power of 200 Kw to 300 Kw and the vacuum condition, demolding is carried out after cooling, and the high-temperature alloy is prepared. The content of oxygen and the content of nitrogen are both smaller than 100 ppm; according to the Ni-Cr-Nb intermediate alloy with the melting point being 1250 DEG C or below, the smelting time is shortened, the power consumption needed by smelting is reduced, and the purity of the obtained high-temperature alloy is high.

The present inventions concerns a copolymer of ethylene and an C3 to C8 alpha-olefin, wherein the copolymer has a density of 870 to 890 kg / m3 measured according to ISO 1183, a MFR2 of 0.5 to 8.0 g / 10 min measured according to ISO 1133, wherein the alpha-olefin is present in the copolymer in an amount of 20 to 35 wt.-%, wherein the copolymer has a first melting temperature Tm1 measured according to ISO 11357-3, characterized in that the first melt point Tm1 is between 90 and 115° C.

The invention relates to the technical field of casting materials, and particularly discloses a rare earth alloying nucleating agent. According to the rare earth alloying nucleating agent, rare earth elements are added on the basis of a traditional silicon-based nucleating agent, the rare earth elements can react with S, O and N in molten iron to generate rare earth sulfide, oxide and nitride particles, and the particles can serve as nucleation substrates of graphite. The melting point of the particles is higher than the temperature of molten iron, so that the nucleation number of rare earth inoculation is large, the anti-recession time is long, the inoculation effect can be ensured, graphite is finer, and the strength of a casting is improved.

The invention discloses alloy material smelting equipment, and relates to the technical field of alloy smelting, the alloy material smelting equipment comprises supporting seats, a discharging assembly and a crushing assembly, the two supporting seats are connected with first rotating shafts through bearings, a smelting box is fixedly connected between the two first rotating shafts, and an inner container and a heating coil are arranged in the smelting box; a crushing assembly is arranged above the supporting seat; the crushing assembly comprises a crushing box, and a feeding hole is formed in the top of the crushing box. An alloy material is crushed through the crushing assembly, the crushed alloy material is divided into a plurality of parts, the size is reduced, and heat can be quickly transferred from the surface to the interior during heating, so that the overall temperature of the alloy material is quickly increased, the alloy material is easier to reach a melting point to be melted, rapid smelting of the alloy material is realized, and the smelting efficiency is improved; the size of the crushed alloy material is smaller, and the internal space of the smelting box is fully utilized, so that more alloy materials can be accommodated in the smelting box.

The invention relates to a high-throughput preparation method of a metal material. The high-throughput preparation method comprises the following steps: 1) preparing a to-be-researched metal material into a component with a set structure; wherein a plurality of grooves are formed in the component, and the plurality of grooves are communicated with one another through communicating grooves; (2) adding an additive material containing an element to be researched into the groove of the component to obtain the component containing the additive material; wherein the melting point of the additive material is lower than that of the metal material to be researched; (3) the component containing the additive material is heated, so that at least part of the additive material is melted to form a liquid phase, and diffusion of elements in the liquid phase is achieved; the temperature of the heating treatment is lower than the melting point of the metal material to be researched. According to the invention, the problem that the traditional diffusion joint can only realize high-throughput preparation of solid / solid phase change component tissue gradient samples and cannot realize high-throughput preparation of liquid / solid component tissue gradient samples is solved, so that an effective method is provided for accelerating the development of novel alloy materials.

A composite material includes a plurality of polypropylene sheet layer unit groups that are sequentially stacked; each polypropylene sheet layer unit group comprises at least one of the same or different polypropylene sheet layer units, the structure of each polypropylene sheet layer unit is BiAiB′i; the structure of the polypropylene composite material is . . . i-th group, . . . second group, first group, second group, . . . i-th group, . . . ; the melting point of polypropylene composition Ai is greater than the melting point of polypropylene compositions Bi and B′i; and the average value of the melting points of all outer layers in the i-th group is greater than the average value of the melting points of all outer layers in an (i-1)th group. The polypropylene composite material has a very good tensile property and very good impact resistance, and also has good interlayer stripping strength at a relatively low hot-pressing temperature.

The invention relates to the technical field of high polymer materials, and particularly discloses a production process of spherical wax micropowder, which comprises the following steps: melting solid wax into a wax melt, and preserving at a constant temperature in an environment which is at least 20 DEG C higher than the melting point of the wax; the wax melt and hot water are mixed according to the flow ratio of 1: (10-20) and then sprayed out to form mist spray, the mist spray enters mist spray pool water with the temperature of the wax melting point + / -5 DEG C, and wax liquid drops in the mist spray are subjected to condensation polymerization in the mist spray pool water to form spherical wax melt; the spherical wax melt gradually rises into cooling water flow in the water of the spraying pool, the temperature of the cooling water flow is 10-20 DEG C lower than the wax melting point, the spherical wax melt flows in the cooling water flow and is cooled, the spherical wax melt is separated from the cooling water flow, and dewatering and drying are conducted to obtain the spherical wax micro powder. The process can improve the sphericity and particle size uniformity of the wax micro powder.

The invention relates to the technical field of metallurgy and chemical industry, in particular to a silicon-manganese alloy smelting method which comprises the following steps of raw material pretreatment, gradient reduction smelting, tapping and refining and flue gas slag cooperative treatment. In the silicon-manganese alloy smelting process, lanthanum-cerium oxide in the rare earth composite material reacts with impurities such as sulfur, phosphorus and oxygen in a melt at high temperature to form a high-melting-point compound which is separated along with slag, the impurity content is effectively reduced, meanwhile, rare earth elements are segregated at the grain boundary, atomic diffusion migration is inhibited, the alloy grain size is remarkably refined, and the alloy yield is improved. And the rare earth composite material optimizes the alloy solidification structure through the double effects of chemical purification and physical modification, the problems of impurity segregation and insufficient toughness in the traditional silicon-manganese alloy smelting process are solved, and the mechanical property of the silicon-manganese alloy is remarkably improved.

The invention relates to a matrix structure for growing a diamond film and a preparation method of the diamond film, the matrix structure comprises a substrate, a buffer layer, a heat conduction layer and a heat conduction substrate, the material of the substrate comprises graphite; the buffer layer covers at least part of the surface of the substrate; the buffer layer is provided with a first surface and a second surface which are oppositely arranged, the first surface comprises a growth surface, the second surface comprises a heat conduction surface, and the growth surface is used for growing a diamond film. The heat-conducting layer is arranged on the heat-conducting surface. The melting point of the heat conduction layer is not higher than the melting point of the heat conduction substrate and the melting point of the buffer layer. The matrix structure is rapid in heat transfer, relatively uniform in temperature, small in thermal stress, free of film cracking during growth of the diamond film, good in growth quality and capable of achieving a relatively large thickness.