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| Brand Name : | KEGU |
| Price : | 200-500 yuan/kg |
| Payment Terms : | L/C,D/A,D/P,T/T,Western Union,MoneyGram |
| Supply Ability : | 2,000 pcs/month |
| Model Number : | Customizable |
Product Description
Our advanced silicon nitride ceramic heater protection tubes are engineered to deliver superior performance in aluminum melting and holding applications. With enhanced thermal and mechanical properties compared to conventional materials, silicon nitride enables reliable, long-lasting protection for your heating systems.
Key Advantages of Silicon Nitride Protection Tubes
Excellent High-Temperature Performance: Si3N4 is the ideal material for electric and gas heater protection tubes, offering superior high-temperature strength and thermal shock resistance (ΔT 400–500°C).
Extended Service Life: Withstands prolonged thermal loads from heating elements or burners, providing reliable operation for over one year.
Improved Energy Efficiency: Submerged heating with silicon nitride protection tubes can achieve 20–30% higher energy efficiency compared to traditional top radiant heating methods.
Prevents Molten Aluminum Oxidation: Minimizes overheating and oxidation of the upper aluminum layer, ensuring better metal quality.
Non-Reactive with Molten Aluminum: Does not contaminate the molten aluminum bath, helping to maintain metal purity and consistency.

Category | Property | Unit | 99% Al₂O₃ | S-SiC | ZrO₂ | Si₃N₄ |
Physical | Density | g/cm³ | 3.9 | 3.1 | 6.0 | 3.2 |
Water Absorption | % | 0 | 0.1 | 0 | 0.1 | |
Sintering Temperature | °C | 1700 | 2200 | 1500 | 1800 | |
Mechanical | Hardness (HV) | HV | 1700 | 2200 | 1300 | 1400 |
Flexural Strength | MPa (kgf/mm²) | ~343 (3500) | ~392 (4000) | ~882 (9000) | ~686 (7000) | |
Compressive Strength | MPa (kgf/mm²) | ~2942 (30000) | ~1961 (20000) | ~1961 (20000) | ~2255 (23000) | |
Thermal | Max Working Temperature | °C | 1500 | 1600 | 1300 | 1400 |
Thermal Expansion Coefficient (0-1000°C) | 10⁻⁶/°C | 8.0 | 4.1 (0-500°C) | 9.5 | 2.0 (0-500°C) | |
5.2 (500-1000°C) | 4.0 (500-1000°C) | |||||
Thermal Shock Resistance | ΔT (°C) | 200 | 250 | 300 | 400-500 | |
Thermal Conductivity (25°C) | W/m·K | 31 | 100 | 3 | 25 | |
Thermal Conductivity (300°C) | W/m·K | 16 | 100 | 3 | 25 | |
Electrical | Volume Resistivity (20°C) | Ω·cm | >10¹² | 10⁶–10⁸ | >10¹⁰ | >10¹¹ |
Volume Resistivity (100°C) | Ω·cm | 10¹²–10¹³ | – | – | >10¹¹ | |
Volume Resistivity (300°C) | Ω·cm | >10¹² | – | – | >10¹¹ | |
Dielectric Strength | kV/mm | 18 | Semiconductor | 9 | 17.7 | |
Dielectric Constant (1 MHz) | ε | 10 | – | 29 | 7 | |
Dielectric Loss Tangent | tan δ | 0.4 × 10⁻³ | – | – | – |


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