High purity graphite crucible material has the advantages of high sublimation temperature, high mechanical strength, self lubrication and heat shock resistance, but it is oxidized in the oxygen atmosphere higher than 4500C. In order to further improve the graphite plate, graphite rod graphite products, high temperature resistance, wear resistance and corrosion resistance, has been the emergence of a coated graphite materials, graphite products in surface impregnated or coated with a layer of metal or metal compounds in order to improve the performance of graphite.
The main application of high purity graphite crucible:
The main purpose of high purity graphite crucible is melting and experiment of metal. Because of the high boiling point of metal melting, other materials and ordinary ceramic crucibles will also melt, which does not meet the requirements. The melting point of graphite is ideal at 3652 degrees, and corrosion resistance and strength are good.
The main advantages of high purity graphite crucible:
High purity graphite has the advantages of small resistance coefficient, high temperature resistance, corrosion resistance, oxidation resistance, good thermal shock resistance, small conductivity, thermal conductivity, low expansion coefficient, self lubrication, easy precision machining and so on.
1. high temperature resistance type: Graphite melting point is 3850 + 50 degrees, boiling point is 4250 degrees, even if the ultra-high temperature arc ignition, the weight loss is very small, the thermal expansion coefficient is very small. The strength of graphite increases with the increase of temperature, and the strength of graphite is doubled at 2000.
2. conductivity and thermal conductivity: the conductivity of graphite is one hundred times higher than that of ordinary non-metallic minerals. Thermal conductivity is higher than that of steel, iron, lead and other metal materials. The thermal conductivity decreases with the increase of temperature, even at extremely high temperature. Graphite can conduct electricity because each carbon atom in graphite has only 3 covalent bonds with other carbon atoms, and each carbon atom still retains 1 free electrons to transport charges.
3. lubricity: graphite lubrication performance depends on the size of graphite scales, the larger the scale, the smaller the friction coefficient, the better the lubrication performance.
4. chemical stability: graphite has good chemical stability at room temperature, and can resist acid, alkali and organic solvent corrosion.
5. plasticity: the toughness of graphite is good, can be rolled into very thin sheet.
6. thermal shock resistance: when graphite is used at room temperature, it can withstand the drastic change of temperature without damaging. When the temperature changes suddenly, the volume of graphite changes little, and cracks do not occur.