Silicon Nitride Protection Tube
Our high-purity silicon nitride protection tubes are made of dense, high-grade Si₃N₄ ceramic via advanced hot-pressing/atmospheric sintering. It features exceptional non-wetting to molten non-ferrous metals (especially aluminum), extreme thermal shock resistance, strong corrosion resistance, and long service life. Ideal for thermocouple protection, heater element sheathing in aluminum smelting, copper alloy casting, high-temperature furnaces, and semiconductor thermal processing. No adhesion, no contamination, stable temperature measurement, reducing maintenance downtime and costs significantly.
Specifications & Customization
1. Standard OD: 16-60 mm, length: 300-2000 mm; one end closed / both ends open available.
2. Custom sizes, wall thickness and flange connections according to customer drawings.
3. High thermal conductivity & high wear resistance models are provided.
Core Performance Advantages:
1. High temperature resistance & thermal shock resistance: Long-term service temperature up to 1400℃, instantaneous temperature resistance up to 1600℃+; no cracking under rapid water cooling from 1000℃, far superior to alumina and silicon carbide ceramics.
2. Non-wetting & anti-slag adhesion: Contact angle with molten aluminum > 140°, reduces aluminum slag adhesion by 95%. After 12 months of continuous operation, slag thickness is only 0.3mm (compared with 12mm for traditional alumina tubes).
3. Strong corrosion resistance: Reacts only with hydrofluoric acid, resistant to strong acids, alkalis, molten metals and furnace slag corrosion.
4. High mechanical strength: Bending strength 800–1200MPa, impact and vibration resistant, not easy to break.
5. Accurate temperature measurement: Fast response, temperature fluctuation controlled within ±2℃, improves product qualification rate.
6. Extra long service life: Stable service for 18–24 months in molten aluminum working conditions, reduces maintenance cost by 70%.
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Item
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Data
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Density
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3.20+0.04g/cm3
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Apparent Porosity
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＜0.3%
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Elastic Modulus
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300-320GPa
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Compression Strength Ratio
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35-45%(25℃)
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Hardness(HRA)
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92-94Gpa
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Fracture Toughness
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7.0-9.0/Mpa.m1/2
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Bending Strength
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800-1000MPa
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Poisson's Ratio
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0.25
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Webuller Modulus
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11-13
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Thermal Conductivity
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22-24w.(m.k)-1
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Corrosion Resistance
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Good
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Size Stability
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Good
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Standard Size
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||
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OD mm
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ID mm
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Length mm
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16
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8
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300-600
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22
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12
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300-800
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28
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16
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300-900
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30
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18
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300-900
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45
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25
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300-900
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1. Non-ferrous Metals: Temperature measurement and heating element protection for aluminum/aluminum alloy smelting, die-casting, continuous casting; molten systems of copper, zinc and other non-ferrous metals.
2. Metallurgy & Heat Treatment: Thermocouple protection for high-temperature furnaces and heat treatment furnaces in steel plants.
3. Photovoltaic & Semiconductor: Components in high-temperature zones of silicon purification and single crystal furnaces.
4. Chemical Industry: Temperature measuring sleeves for high-temperature reactors and corrosive gas environments.
Frequently Asked Questions
Need help? Be sure to visit our support forums for answers to your questions!
We are a real manufacturer, our factory is specialized in producing refractory materials for more than 30 years. We promise to provide the best price, the best pre-sale and after-sale service.
For each production process, RBT has a complete QC system for chemical composition and physical properties. And we will test the goods, and the quality certificate will be shipped with the goods. If you have special requirements, we will try our best to accommodate them.
Depending on the quantity, our delivery time is different. But we promise to ship as soon as possible with guaranteed quality.
Of course, we provide free samples.
Yes, of course, you are welcome to visit RBT company and our products.
There is no limit, we can provide the best suggestion and solution according to your situation.
We have been making refractory materials for more than 30 years, we have strong technical support and rich experience, we can help customers design different kilns and provide one-stop service.
