Refractory materials

Graphite, owing to its unique physicochemical properties, has become a core raw material in the field of refractory materials, with applications spanning multiple industrial sectors such as metallurgy, foundry, and chemical engineering:

I. Core Properties Supporting Refractory Performance

1. High-Temperature Resistance

Graphite has an extremely high melting point of 3,704°C (3,850°C in a vacuum) and remains structurally stable at temperatures up to 3,000°C, making it one of the most heat-resistant non-metallic materials known. For example, in electric arc furnaces for steelmaking, graphite electrodes generate high temperatures (approximately 2,000°C) via electric arcs to melt metals, while remaining unmelted themselves with minimal volatilization loss.

2. Thermal Shock Resistance

Graphite exhibits an exceptionally low coefficient of thermal expansion (averaging just 3.34×10⁻⁶/°C between 25°C and 1,600°C), enabling it to withstand rapid heating and cooling cycles without cracking. For instance, graphite crucibles maintain structural integrity over long-term use due to their superior thermal shock stability during repeated heating and cooling processes.

3. Chemical Stability

Graphite is insoluble in acid, alkali, and salt solutions at room temperature and demonstrates strong resistance to erosion by molten metals and slag. For example, when graphite refractory materials come into contact with molten steel during steelmaking, their surfaces are not easily wetted or corroded, extending equipment lifespan.

4. Thermal Conductivity

Graphite has a high thermal conductivity coefficient (63.8 W/m·°C at 1,000°C), allowing rapid and uniform heat transfer to enhance melting efficiency. For example, graphite crucibles promote even temperature distribution in molten metal by efficiently conducting heat, reducing localized overheating.

II. Application Scenarios

1. Metallurgical Industry: Steelmaking Furnace Linings and Continuous Casting

•Graphite Electrodes: As the core conductive material in electric arc furnaces, graphite electrodes generate high temperatures via electric arcs to melt metals. The global steelmaking industry consumes approximately 70% of all refractory materials in this application.

2. Foundry Industry: Metal Melting and Molding

•Graphite Crucibles: Used for melting non-ferrous metals like copper and aluminum, these crucibles avoid high-temperature cracking due to their low thermal expansion, ensure repeated use through thermal shock stability, and promote uniform heating via high thermal conductivity. For example, after replacing traditional clay crucibles with silicon carbide-graphite crucibles, the consumption of large-flake graphite decreased from 45% to 30%, carbon content dropped to 80%, and costs were reduced while performance remained stable.

•Mold Materials: Graphite molds for ferrous metal casting deliver high dimensional accuracy and smooth surface finishes due to their low expansion coefficient, improving product yield and reducing post-processing costs.

3. Chemical and High-Temperature Industries: Equipment Manufacturing

•Heat Exchangers and Reaction Vessels: Graphite’s corrosion resistance and low permeability make it ideal for fabricating heat exchangers, reaction tanks, coolers, and other equipment in petrochemical and hydrometallurgical applications, replacing metal materials to lower costs.

•High-Temperature Metallurgical Containers: High-purity graphite-processed vessels, such as single-crystal silicon growth crucibles and zone refining containers, meet stringent requirements for high temperatures and chemical stability.