Graphite Felt for Single-Crystal and Polycrystalline Silicon Smelting Furnaces

Product Description

Core Applications

In furnaces used for the smelting of monocrystalline and polycrystalline silicon, graphite felt serves primarily as a high-performance thermal insulation material. It effectively maintains the stability of the internal temperature field, reduces energy consumption, and enhances both the quality of crystal growth and the operational lifespan of the equipment.

These high-temperature furnaces are required to operate in non-oxidizing atmospheres at temperatures exceeding 2000°C, placing extremely stringent demands on the thermal resistance and chemical stability of the materials used. By virtue of its unique physical structure and superior properties, graphite felt has become an indispensable and critical component within these thermal field systems.

1. Thermal Insulation Cylinders and Heat Shields
Encasing the heater and crucible systems, the felt forms a highly efficient thermal insulation layer that significantly reduces heat loss and improves energy utilization efficiency. By precisely adjusting the thickness and layering of the felt, axial and radial temperature gradients can be accurately controlled to meet the specific thermal field requirements of different stages of crystal growth (such as "shouldering" and "constant diameter" growth).

2. Furnace Bottom and Wall Insulation Layers
Installed within the interior of the furnace body, these layers prevent the conduction of high temperatures to the exterior, thereby protecting the metal shell and sealing structures while simultaneously maintaining temperature uniformity within the furnace chamber.

3. Flow Guide Tubes and Support Structure Linings
When used in combination with rigid graphite materials, the felt enhances resistance to gas flow erosion, optimizes gas flow paths within the furnace, minimizes impurity disturbance, and improves the purity of the monocrystalline silicon.

Furthermore, high-purity graphite felt (with a carbon content of ≥99.99%) is capable of adsorbing impurities present in silicon monoxide (SiO) vapor and halogen gases, thereby mitigating the risk of contamination and extending the service life of thermal field components.

performance

1. Corrosion Resistance: Suitable for chemically corrosive environments, not easily damaged by long-term use, suitable for photovoltaic, battery manufacturing, and other industrial fields.

2. High Temperature Resistance: Remains stable at 2800ºC (in an oxygen-free environment or under inert gas protection), suitable for high-temperature furnaces, single crystal production equipment, etc.

3. Application Characteristics:
Shape Retention: Maintains its original structure after long-term use, suitable for vacuum insulation and heat insulation materials.
Purity: Ash content below 500 ppm, suitable for high-precision equipment.

Characteristics

Advantages

1. High Conductivity and Mass Transfer Efficiency
PAN-based graphite felt possesses high conductivity (electron mobility up to 10 S/m), and its three-dimensional network structure shortens the vanadium ion transport path, significantly improving charge transfer efficiency. Experimental data shows that its charge transfer impedance can be reduced to 70 mΩ·cm², approximately 90% lower than that of unmodified electrodes.

2. Antioxidant and High-Temperature Stability
PAN-based graphite felt, through carbonization, forms a stable carbon framework structure with excellent antioxidant properties, maintaining material integrity even at high temperatures. This is crucial for the electrolyte stability of vanadium-ion batteries, preventing material decomposition during high-temperature operation.

3. Low-Temperature Activation Performance
Its catalytic activity can be further enhanced through surface modification (such as nitrogen doping or vertical graphene modification). For example, the team at Southern University of Science and Technology (SUSTech) fabricated a nitrogen-doped vertical graphene/graphite felt electrode using a metal-free CVD method. After 1500 cycles at a current density of 300 mA/cm², the electrode maintained an energy efficiency of 80.2% and achieved a peak power density of 1308.56 mW/cm².

4. Mechanical Strength and Corrosion Resistance
PAN-based materials inherently possess high tensile strength (300 MPa) and good chemical stability, maintaining structural integrity for extended periods in acidic electrolytes. This characteristic ensures the mechanical stability of the battery during frequent charge-discharge cycles, extending its lifespan.