What are the advantages of graphite crucibles? A corundum crucible manufacturer explains.

      Corundum crucible The manufacturer believes High-purity graphite crucible materials have excellent properties such as high sublimation temperature, high high-temperature mechanical strength, good self-lubrication, and good thermal shock resistance, but they will be oxidized at temperatures above 450 in an oxygen-containing atmosphere. In order to further improve the high-temperature resistance, wear resistance, and corrosion resistance of graphite products such as graphite plates and graphite rods, a coated graphite material has emerged, which is to coat or impregnate a layer of metal or metal compound on the surface of graphite products to improve the performance of graphite.

　　 Corundum crucible The manufacturer believes Main uses of high-purity graphite crucibles: The main uses of high-purity graphite crucibles are metal smelting and experiments. Due to the high melting and boiling points of metals, other materials and ordinary ceramic crucibles will also melt and do not meet the requirements. The melting point of graphite is 3652, which is relatively ideal, and it has good corrosion resistance and strength.

　　 Corundum crucible The manufacturer believes Main advantages of high-purity graphite crucibles: High-purity graphite has advantages such as low resistivity, high temperature resistance, corrosion resistance, oxidation resistance, good thermal shock resistance, low conductivity, low thermal expansion coefficient, self-lubrication, and easy precision processing.

　　1. High-temperature resistant type: Graphite melting is 3850, boiling point 4250. Even with ultra-high-temperature arc combustion, the weight loss is very small, and the thermal expansion coefficient is also very small. The strength of graphite increases with increasing temperature, doubling at 2000.

　　2. Electrical conductivity and thermal conductivity: Corundum crucible The manufacturer believes The electrical conductivity of graphite is one hundred times higher than that of ordinary non-metallic minerals. The thermal conductivity exceeds that of steel, iron, lead, and other metal materials. The thermal conductivity decreases with increasing temperature, and even at extremely high temperatures, graphite will become an insulator. Graphite can conduct electricity because each carbon atom in graphite only forms three covalent bonds with other carbon atoms, and each carbon atom retains a free electron to transfer charge.

　　3. Lubricity: The lubricity of graphite depends on the size of the graphite flakes. The larger the flakes, the smaller the coefficient of friction and the better the lubricity.

　　4. Chemical stability: Graphite has good chemical stability at room temperature and can resist corrosion by acids, alkalis, and organic solvents.

　　5. Plasticity: Graphite has good toughness and can be ground into thin sheets.

　　6. Thermal shock resistance: Corundum crucible The manufacturer believes When used at room temperature, graphite can withstand drastic temperature changes without damage. When the temperature changes suddenly, the volume change of graphite is small, and no cracks will appear.

　 　Corundum crucible The manufacturer believes that graphite is the main raw material for producing crucibles, accounting for 45 ~ 55% of the ingredients, especially flake graphite and acicular (block) graphite. Flake graphite is widely used in the production of graphite crucibles in China, and the carbon content is generally 85 ~ 93%. The graphite particle size is selected according to the performance, use, model, and specifications of the crucible. Usually, large crucibles with a volume greater than 100# are made of large-size graphite above 32 mesh. Medium crucibles with a volume of 60 ~ 80# use 80-mesh flake graphite; small crucibles with a volume of less than 50# are made of 100-mesh flake graphite; and irregularly shaped crucibles made by hand use -100-mesh fine flake graphite.