Technical progress examples of the application of graphite powder in heat conduction and heat dissipation materials

Graphite is a kind of carbon material widely used in many fields of national economy. It is an allotrope of carbon with carbon black, diamond, carbon 60, carbon nanotube, graphene and so on. In brief, graphite has the characteristics of temperature resistance, conductivity, thermal conductivity, lubricity, chemical inertia, plasticity and other characteristics. Graphite is commonly used in the manufacture of refractory materials, conductive materials, wear-resistant materials, lubricating materials, high-temperature sealing materials, corrosion-resistant materials, thermal insulation materials, adsorption materials, friction materials and radiation protection materials.

Examples of new technological progress of graphite powder in the field of heat conduction and heat dissipation materials:

Patent CN 111040696 A published a high thermal conductivity magnetic shielding high-strength waterproof potting adhesive made of graphite powder. It has high thermal conductivity, good waterproof performance and high tensile strength, and has good application prospects.

The raw material formula of the high thermal conductivity magnetic shielding high strength waterproof potting adhesive described in the patent includes one or more of the following raw materials by weight: alumina 25-35, silicon carbide 5-15 and aluminum nitride 5-35 or more; One or more of flake nickel powder 1-8 parts, hydroxyl iron powder 3-15 parts, iron silicon aluminum 2-40 parts, iron nickel powder 10-38 parts; One or more of 5-40 parts of graphene, 1-9 parts of graphite powder, 3-18 parts of graphite powder; Epoxy 2-7 parts, polyurethane 1-9 parts.

The high thermal conductivity magnetic shielding high-strength waterproof potting adhesive prepared by the invention is used for electronic potting and has high strength, waterproof, good thermal conductivity effect, good insulation and magnetic shielding effect, and the preparation process of the high thermal conductivity magnetic shielding high-strength waterproof potting adhesive is simple, low production energy consumption and no "three wastes".

Patent CN 111149442 A published a method for producing a thermal conductive film using synthetic graphite powder. Compared with the existing natural graphite film or metal film, the thermal conductive film has excellent thermal conductivity and lower production cost.

The existing production process of thermally conductive graphite film calcines expensive polymer films such as polyimide film at 2000℃ to 3000℃. The cost of raw materials and equipment is relatively high, and it is difficult to produce roll products with large width (such as 1000mm).

The manufacturing method of the thermal conductive film includes:

① Pretreatment of synthetic graphite powder under pressure or reduced pressure;

② Adding an embedding agent to the pretreated synthetic graphite powder;

③ The synthetic graphite powder with intercalation agent was heat treated;

④ Rolling heat treated synthetic graphite powder.

Patent CN 110436940 A published a preparation method of high thermal conductivity carbon/carbon composites. Due to the excellent high temperature mechanical properties and good ablation resistance of carbon/carbon composites, they have been successfully used to prepare key components of solid rocket motors such as throat lining and gas rudder.

Based on the technical problem that the crushing process of graphite is not disclosed in the existing technical scheme, which is easy to cause too large gap in the finished carbon/carbon composite and affect the quality, the invention proposes a preparation method of high thermal conductivity carbon composite.

Firstly, the graphite is placed on the ultrasonic cleaning machine, and the KOH aqueous solution configured according to 2.5% is poured into the ultrasonic cleaning machine. The graphite is cleaned by ultrasonic. After cleaning, it is put into the hot air box for drying, and the graphite is cut by the cutter to make it a block with uniform size.

Put the cut graphite into the pulverizer for preliminary crushing, and put the crushed graphite particles into the vibrating screen, so as to obtain graphite particles with uniform size. At the same time, because the graphite is in the shape of particles with uniform size, it is convenient to crush the graphite, and then place the crushed graphite particles on the grinding machine, In this way, the graphite particles are ground by the grinding machine to make the graphite particles present particles with basically the same size. Finally, the graphite particles are put into the oscillation box to vibrate the graphite to make the graphite present a fluffy state.

By cleaning, cutting, crushing and grinding the graphite, the invention can realize uniform crushing of the graphite, so that the obtained graphite can form powder particles with uniform size. Therefore, when the graphite is pressed later, there will be no gap and quality problems.

Patent CN 111154271 A published a thermal conductive silicone grease with high thermal conductivity and a preparation process thereof. It relates to the technical field of thermal conductive interface materials for high-power electronic and electrical equipment. The thermal grease of the invention is composed of the following components: powder 60-90; Silicone oil 10-0 parts; Coupling agent 1-5 parts; The powder is a mixture of alumina, zinc oxide and graphite powder, wherein, the powder is composed of the following components by weight: alumina: 20-35; Zinc oxide: 10-15 parts; Graphite powder: 60-70 parts. The particle size of alumina is 10-40 microns, the particle size of graphite powder is 1-30 microns, and the particle size of zinc oxide is 1-5 microns.

The invention can further reduce the thermal resistance of thermal silicone grease and accelerate the heat absorption of thermal silicone grease to the heat source by matching a variety of powder with different particle sizes.Alumina and zinc oxide with graphite powder, can form a kind of modified coated graphite powder. The modified coated graphite powder has a good bonding interface in the silicone oil, the main component of thermal conductive silicone grease, which is conducive to its dispersion in thermal conductive silicone grease, and can improve their compatibility and affinity, so as to reduce the contact thermal resistance between the two interfaces and improve the thermal conductivity. The thermal conductivity of graphite powder as one of the additives is 150-300W/(M·K). The addition of graphite powder greatly improves the overall thermal conductivity of the product. Low cost, suitable for industrial production and use, the related technical news talk with us.