Density and Heat Resistance of Graphite Rods

Main Uses of Graphite Rods: Graphite rods are commonly used in the metallurgy and machinery industries, particularly as heating elements in high-temperature vacuum furnaces, with a maximum operating temperature of up to 3000°C. They are prone to oxidation at high temperatures and can only be used in neutral or reducing atmospheres, except in vacuum conditions.

1. High-Temperature Resistance: Graphite rods are among the most heat-resistant materials known. They have a melting point of 3850°C ± 50°C and a boiling point of 4250°C. When subjected to a 7000°C ultra-high temperature electric arc for 10 seconds, graphite rods exhibit minimal loss, with a weight loss of 0.8%. This demonstrates their outstanding high-temperature performance.
2. Special Thermal Shock Resistance: Graphite rods have excellent thermal shock resistance, meaning they have a low coefficient of thermal expansion and good thermal stability. They do not crack under sudden temperature changes.
3. Thermal and Electrical Conductivity: Graphite rods possess excellent thermal and electrical conductivity, outperforming many materials. Their electrical conductivity is four times higher than stainless steel, twice that of carbon steel, and 100 times that of typical non-metallic materials. Their thermal conductivity surpasses that of steel, iron, and lead, and decreases with increasing temperature, unlike most metals. At extremely high temperatures, graphite can become nearly adiabatic, making its thermal insulation properties very reliable in such conditions.
4. Lubricity: The lubricating properties of graphite rods are similar to molybdenum disulfide, with a friction coefficient of less than 0.1. The larger the graphite flakes, the lower the friction coefficient and the better the lubricating properties.
5. Chemical Stability: Graphite rods exhibit good chemical stability at room temperature, resisting corrosion from acids, alkalis, and organic solvents.

Graphite is a crystalline form of carbon, a non-metallic material that is silver-gray in color, soft, and has a metallic luster. Its Mohs hardness is 1-2, with a specific gravity of 2.2-2.3 and a bulk density generally between 1.5 and 1.8.

Applications of Graphite Rods:

1. Refractory Materials: Graphite rods and products possess high-temperature resistance and high strength, making them suitable for producing graphite lubricants and protecting steel ingots in the metallurgy industry, as well as lining metallurgical furnaces.
2. Conductive Materials: In the electrical industry, graphite rods are used to make electrodes, brushes, carbon rods, carbon tubes, mercury rectifier anodes, graphite gaskets, telephone parts, and TV picture tube coatings.
3. Wear-Resistant Lubricating Materials: In the machinery industry, graphite rods often serve as lubricants, capable of operating at high sliding speeds in temperatures ranging from 200 to 2000°C without the need for lubricating oil. Graphite materials are used for pistons, seals, and bearings in equipment that handles corrosive media, functioning without adding lubricating oil.
4. Chemical Stability: Specially processed graphite rods have properties such as corrosion resistance, good thermal conductivity, and low permeability. They are widely used in heat exchangers, reaction vessels, condensers, combustion towers, absorption towers, coolers, heaters, filters, and pump equipment in industries like petrochemicals, hydrometallurgy, acid-base production, synthetic fiber, and paper manufacturing, saving a significant amount of metal materials.
5. Casting, Molding, and High-Temperature Metallurgical Materials: Graphite rods’ low thermal expansion coefficient and resistance to rapid temperature changes make them suitable for casting molds, yielding precise and smooth castings. They are also used in the powder metallurgy process to make molds and sintering boats.
6. Nuclear and Defense Industries: Graphite rods are excellent neutron moderators for nuclear reactors. The uranium-graphite reactor is one of the most widely used nuclear reactors. Graphite used in reactors must have a high melting point, stability, and corrosion resistance. The graphite purity for reactor use must be high, with impurity content not exceeding a few parts per million (PPM), especially boron, which should be less than 0.5 PPM.
7. Scale Prevention in Boilers: Adding a certain amount of graphite powder to water (about 4-5 grams per ton) can prevent scale formation on boiler surfaces. Graphite rods are also used for corrosion and rust prevention on metal chimneys, roofs, bridges, and pipelines.
8. Pencil Leads, Pigments, and Polishing Agents: Graphite rods can be processed into various special materials for industrial use, such as pencil leads, pigments, and polishing agents.

These characteristics and applications demonstrate the wide-ranging utility of graphite rods in modern industries.