Molten Aluminum Thermocouple (Sialon / Silicon Nitride)
In the aluminum die-casting and foundry industries, standard cast iron protection tubes are a major pain point. They erode quickly (lasting only 3-4 weeks), contaminate the melt with iron, and require constant replacement. The Hongtai Molten Aluminum Thermocouple utilizes advanced ceramic technology to solve these problems.
Featuring a premium Silicon nitride sheath (often referred to as Sialon), this Foundry temperature sensor offers exceptional thermal shock resistance and a service life of up to 12 months in molten aluminum, zinc, and magnesium. This drastic increase in durability translates to reduced downtime and cleaner metal for high-quality castings.
Key Technical Features & Benefits
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Non-Wetting Surface: The defining feature of a Sialon protection tube is its “Non-wetting” property. Molten aluminum does not stick to the surface. This means no slag buildup, no messy cleaning, and consistently accurate temperature readings.
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12-Month Lifespan: While cast iron tubes fail within a month, Sialon tubes are chemically inert to aluminum attack, providing a lifespan 10-15x longer than traditional metal tubes.
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Iron-Free Purity: Because the sheath is ceramic, there is zero risk of iron leaching into your alloy. This is critical for manufacturing aerospace components and premium automotive wheels.
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High-Strength: Sialon is one of the strongest structural ceramics, capable of withstanding mechanical impact during ladle skimming better than standard oxide ceramics.
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Thermocouple Core: Available with Type K or Tungsten Rhenium (Type W) cores for higher temperature stability.
Technical Specifications (WRN-M Series)
| Parameter | Specification | Notes |
| Product Type | Molten aluminum thermocouple | L-Shape or Straight |
| Protection Tube | Silicon Nitride (Si3N4) / Sialon | Gray color, ultra-smooth |
| Standard Sizes | OD: 16mm, 22mm, 28mm, 45mm | ID matched to core |
| Core Calibration | Type K (NiCr-NiAl), Type N | Standard for Aluminum |
| Temp Range | 0°C – 800°C (Aluminum) | Up to 1200°C (Copper/Brass) |
| Response Time | < 60 seconds | Faster than Cast Iron |
| Mounting | 90° Elbow (L-Shape) | Keeps head away from heat |
| Connection Head | Heavy Duty Cast Aluminum | IP65 Protected |
Application Scenarios
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Aluminum Die Casting: Holding furnaces and ladles where precise temperature control prevents casting defects (porosity/shrinkage).
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Wheel Manufacturing: Low-pressure die casting requires ultra-clean aluminum; our Non-wetting thermocouple ensures no inclusions.
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Smelting & Recycling: Monitoring large reverberatory furnaces.
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Non-Ferrous Alloys: Also suitable for Zinc (Galvanizing) and Magnesium melting.
Why Sialon is the Smart Investment
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Initial Cost: Higher than Cast Iron.
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Operating Cost: Significantly Lower.
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Scenario: If you replace a $50 cast iron tube every month, you spend $600/year + 12 labor hours. A single Sialon tube costs more upfront but lasts the whole year with zero maintenance labor. The ROI is typically achieved within 3-4 months.
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FAQ
Q: Does it require pre-heating?
A: Sialon has excellent thermal shock resistance compared to Alumina, but for maximum longevity, we recommend pre-heating the tube above the melt for 5-10 minutes before plunging it into 700°C aluminum.
Q: Can I use this for molten copper?
A: Yes, but the lifespan will be shorter due to the higher temperatures (1100°C+). For copper, we recommend specific heavy-wall formulations.
See our Wear Resistant Thermocouples for abrasive environments.
