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.
Technical Property Comparison: Silicon Nitride vs. Other Ceramics
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 | – | – | – |
