As the material of exothermic welding mold, graphite has the following characteristics: 1) High temperature resistance: The melting point of graphite is 3850±50℃, and the boiling point is 4250℃. Even if burned by ultra-high temperature arc, the weight loss is very small, and the thermal expansion coefficient is also very small. The strength of graphite increases with increasing temperature. At 2000°C, the strength of graphite doubles. The temperature of the chemical reaction that ignites the exothermic flux during the exothermic welding construction is very high, so the material used in the exothermic welding mold needs to be resistant to high temperatures. 2) Electrical and thermal conductivity: The electrical conductivity of graphite is one hundred times higher than that of general non-metallic minerals. The thermal conductivity exceeds that of metal materials such as steel, iron, and lead. Thermal conductivity decreases with increasing temperature, even at extremely high temperatures, graphite becomes an insulator. Graphite can conduct electricity because each carbon atom in graphite forms only 3 covalent bonds with other carbon atoms, and each carbon atom still retains 1 free electron to transfer charge. In the exothermic welding construction, it is often necessary to weld a lot of points, and the amount of construction is not small. The thermal conductivity of graphite can meet this point, which can withstand high temperatures and can quickly cool down. 3) Lubricity determines the thoroughness of separation: The graphite block of the exothermic welding mold has a small friction coefficient and good lubricity. After the welding is completed, the separation from the welding material is very thorough. 4) Chemical stability determines use and storage life: the finished exothermic welding mold has good chemical stability at room temperature, and is resistant to acid, alkali and organic solvent corrosion. 5) Durability of exothermic welding mold: Graphite has good toughness and can be crushed into very thin flake. Exothermic welding sometimes requires exothermic welding molds of various joint forms. Easy-processing graphite can be machined into exothermic welding molds of different models, specifications, and connection forms. Based on the above necessary characteristics of exothermic welding molds, we choose high-purity graphite to process the molds.Grade: NX82 Grain size(≤): 0.8mm Bulk Density(≥): 1.72g/cm3 Ash (≤): 0.3% Specific Resistance ≤8.5μΩM Compressive Strength ≥35MPa Flexural Strength ≥13.5MPa Coefficient of Thermal Expansion ≤2.2×10-6/℃The ash content can be purified to 30ppm according to the requirement. / The above index data is the standard value, not the guaranteed value.Grade: NX603 Grain Size(≤): 25μm Bulk Density(≥): 1.80g/cm3 Compressive Strength(≥): 60MPa Flexural Strength(≥): 30MPa Porosity(≤): 17% Specific Resistance(≤): 12μΩm Ash Content(≤): 600ppm Shore Hardness: 50 Coefficient of Thermal Expansion(≤): 5×10-6/℃