Advantages of graphite accessories and electric heating elements for vacuum furnace

Advantages of graphite accessories and electric heating elements for vacuum furnace

     With the improvement of the level of vacuum valve heat treatment furnace, vacuum heat treatment has unique advantages, and vacuum heat treatment has been loved by people in the industry by virtue of a series of advantages such as degassing, degreasing, oxygen free and automation. However, it is noteworthy that the vacuum heat treatment furnace has a high standard for electric heating elements, such as high-temperature deformation, fracture Volatilization has become an important factor restricting the development of vacuum furnace.
     In order to solve this problem, the industry turned its attention to graphite. Graphite is made of other metals and has impeccable advantages. It is understood that graphite is almost popular in different types of vacuum heat treatment furnaces as an electric heating element.
    Then the advantages of graphite vacuum heat treatment electric heating elements
1) High temperature resistance: the melting point of graphite is 3850 ± 50 ℃ and the boiling point is 4250 ℃. Even if it is burned by ultra-high temperature arc, the weight loss is very small and the coefficient of thermal expansion is very small. The strength of graphite increases with the increase of temperature. At 2000 ℃, the strength of graphite is doubled.
2) Conductivity and thermal conductivity: the conductivity of graphite is 100 times higher than that of general non-metallic minerals. Thermal conductivity exceeds that of steel, iron, lead and other metal materials. The thermal conductivity decreases with the increase of temperature. Even at extremely high temperature, graphite becomes an insulator. Graphite can conduct electricity because each carbon atom in graphite forms only three covalent bonds with other carbon atoms, and each carbon atom still retains one free electron to transfer charge.
3) Lubricity: the lubrication performance of graphite depends on the size of graphite scale. The larger the scale, the smaller the friction coefficient, and the better the lubrication performance. Chemical stability: graphite has good chemical stability at room temperature and can resist acid, alkali and organic solvent corrosion.
4) Plasticity: graphite has good toughness and can be ground into very thin sheets. Thermal shock resistance: when graphite is used at room temperature, it can withstand the drastic change of temperature without damage. When the temperature changes suddenly, the volume of graphite changes little and cracks will not occur.
    When designing and processing the vacuum furnace, we should consider that the resistance of the electric heating element changes little with temperature and the resistivity is stable, so graphite is the preferred material.