Hexagonal boron nitride and its composite materials prepared by hot press sintering are ideal high-temperature thermal insulation materials for their excellent high-temperature resistance, resistance to metal melt and slag corrosion, high thermal conductivity and high electrical insulation, as well as easy processing performance, high processing accuracy (up to 0.01mm), low density, lubricating and non-toxic. Its main properties: 1. High heat resistance: oxidation starts at 900℃ in an oxidation atmosphere, and can be safely used to 2000℃ under vacuum, and 2800℃ does not soften in an inert gas; its strength is 1800℃ twice that of room temperature, 2. High thermal conductivity: The hot pressed product is 33W
Hexagonal boron nitride and its composite materials prepared by hot press sintering are ideal high-temperature thermal insulation materials for their excellent high-temperature resistance, resistance to metal melt and slag corrosion, high thermal conductivity and high electrical insulation, as well as easy processing performance, high processing accuracy (up to 0.01mm), low density, lubricating and non-toxic.
Its main performance:
1. High heat resistance: oxidation starts at 900℃ in an oxidation atmosphere, and can be safely used to 2000℃ under vacuum, and 2800℃ does not soften in an inert gas; its strength is 1800℃ twice that of room temperature.
2. High thermal conductivity: The hot-pressed product is 33W/m·k, just like pure iron, and is a material with a high thermal conductivity of ceramic materials above 530℃;
3. Low thermal expansion coefficient: The expansion coefficient of 2×10-6 is second only to quartz glass, and is small and medium-sized ceramics.
4. Excellent electrical properties: good high-temperature insulation, 25℃ is 1014Ω-cm, and 2000℃ can also reach 103Ω-cm. It is a good high-temperature insulation material in ceramics, with a breakdown voltage of 3KV/mm. Low dielectric loss, 2~5×10-4 at 108Hz, dielectric constant is 4, and can transmit microwave and infrared rays;
5. Good corrosion resistance: does not react with general metals (iron, copper, aluminum, lead, etc.), rare earth metals, precious metals, semiconductor materials (germanium, silicon, potassium arsenide,), glass, molten salts (crystalline stone, fluoride, slag), inorganic acids and alkalis;
6. Low friction coefficient: μ is 0.16, and does not increase at high temperature;
7. Mechanical machining: Its hardness is Mohs 2, so it can be processed into parts and products with high accuracy by general machining methods, with processing accuracy up to 0.01mm.
According to the above properties, boron nitride and its composite materials have many uses in cutting-edge technologies such as electronics, metallurgy, chemicals, and aerospace:
1. Using the excellent chemical stability of hexagonal boron nitride ceramics, it can be used as crucibles for melting evaporated metals, boats, liquid metal conveying pipes, crucibles for synthesizing GaAs crystals, rocket nozzles, high-power device bases, pipelines for melting metals, pump parts, molds for cast steel, etc.;
2. Using the heat and corrosion resistance of hexagonal boron nitride ceramics, high-temperature components, rocket combustion chamber linings, spacecraft heat shielding, corrosion-resistant parts of magneto-flow generators, etc.;
3. Using the insulating properties of hexagonal boron nitride ceramics, it can be used for insulators of high-voltage and high-frequency electrical equipment and plasma arcs, insulators of various heaters, heating pipe sleeves, and insulating materials for high-frequency electric furnaces.
4. Using the high insulation and high thermal conductivity of hexagonal boron nitride ceramics, the insulated heat dissipation base plate of semiconductor components, the filler of transformers, and high-temperature, high-frequency, and high-voltage insulated heat dissipation components;
5. Using the heat resistance, corrosion resistance and insulation properties of hexagonal boron nitride ceramics, high-temperature insulating components of plasma arcs, plasma welding tools, thermocouple protection tubes for molten metals, and separation rings for horizontal continuous casting, etc.;
6. Using the high frequency low loss, microwave energy transmission windows can be made, and a solid diffusion source with high B content can be used as semiconductors.