| Customization: | Available |
|---|---|
| After-sales Service: | on-Line Service |
| Warranty: | 1 Years |
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Purpose:
The corundum furnace tube is an integral component of various experimental electric furnaces, acting as the inner lining that crucially separates the heating elements from the test materials. It efficiently encloses the heating zone and securely holds the test substances, making it indispensable in high-temperature testing and analytical instruments. This product finds extensive application across numerous industries, including coal testing, metallurgical powder analysis, and in chemical and glass laboratory equipment.
Material & Manufacturing:
Corundum furnace tubes are predominantly crafted from high-quality fused alumina and are available in two specific variants:
Ultra-fine powder-bonded
Clay-bonded
These specifications are meticulously customized to meet user requirements, considering factors such as operating temperature, wear resistance, and chemical corrosion resistance.
Dimensions:
Outer diameter: 15-200 mm
Length: 100-2000 mm
Wall thickness: 3-15 mm
Usage Guidelines:
When utilizing high-temperature testing equipment, it is vital to ensure gradual heating and cooling to effectively minimize the internal stress induced by thermal expansion and contraction. This precaution significantly reduces the risk of cracking, thereby enhancing the tube's durability and extending its service life.
Composition:
The corundum crucible is expertly constructed from porous fused alumina, providing exceptional durability and superior heat resistance.
Applications:
It is perfectly suited for melting samples with weak alkaline fluxes (e.g., anhydrous NaCO),
but is not compatible with strong alkaline fluxes (e.g., NaO, NaOH) or acidic fluxes (e.g., KSO).
Boasting an impressive 99.70% Corundum content,
the crucible can handle a maximum short-term temperature of 1800°C,
and maintains excellent mechanical strength within oxidizing/reducing atmospheres.
It delivers high thermal conductivity with low thermal expansion.
Operating range: 1650-1700°C
It offers outstanding high-temperature insulation and remains
chemically inert to air, steam, H, CO, etc., up to 1700°C.
With 99.35% Corundum,
the maximum short-term temperature is 1750°C,
and the operating range is 1600-1650°C
with stability in oxidizing/reducing atmospheres.
Composed of 85.00% High-Alumina,
it endures a maximum short-term temperature of 1400°C,
and operates effectively at 1290°C.
It possesses good insulation and mechanical strength even in oxidizing/reducing atmospheres.
Providing high thermal conductivity with low thermal expansion,
the crucible remains chemically inert to air, steam, H, CO, etc.
Suitable for For extended longevity and performance. When maintained under consistent temperature settings.
Quartz glass tubes represent a premier category of industrial technical glass, crafted from silicon dioxide (SiO). This remarkable material is the cornerstone of advanced applications due to its exceptional suite of physical and chemical properties, which include:
Softening point: approximately 1730°C
Long-term usability: enduring up to 1100°C
For short durations, can withstand: 1450°C
Virtually impervious to all acidic substances except hydrofluoric acid (HF).
Acid resistance rating:
30 times more durable than ceramics
150 times more robust than stainless steel
Exceptional chemical stability at elevated temperatures, a feature unparalleled by other engineering materials.
Exhibits an extraordinarily low thermal expansion coefficient.
Capable of withstanding sudden temperature variations (e.g., heating to 1100°C and immediate immersion in room-temperature water without fracturing).
Outstanding transmission of light spanning from UV to infrared wavelengths.
Visible light transmission rate: Exceeds 93%
UV spectrum transmission efficiency: Reaches up to 80%+
Boasts a resistivity that's 10,000 times greater than that of conventional glass.
Retains excellent insulating properties even at elevated temperatures.
Usage & Properties
Capable of being used effectively at temperatures reaching up to 1450°C, available in both transparent and opaque forms.
Key Advantages: High purity, outstanding resistance to temperature, large sizes with precision, superb thermal insulation, energy-efficient, and consistently high quality.
Chemical Compatibility
Incompatible with hydrofluoric acid (HF) .
At high temperatures, prone to reactions with strong alkalis and alkali metal carbonates.
Optimal Fluxes
Perfect for the melting of samples using KSO (potassium pyrosulfate) or KHSO (potassium bisulfate).
Additionally compatible with NaSO (sodium pyrosulfate, dried at 212°C) for detailed sample processing.
Best Practices for Quartz Crucible Usage & Maintenance
Primary Chemical Composition: At the core of our RJ SiC Heating Rods, you'll find the remarkable Silicon dioxide (SiO), a key component that powers its superior functionality.
Chemical Resistance: Our rods are fundamentally immune to most acids, with the notable exception of hydrofluoric acid (HF). However, they showcase a reactive nature with caustic alkalis and alkali metal carbonates, demonstrating their unique chemical interactions.
Thermal Stability: These rods exhibit outstanding thermal stability, ensuring consistent performance even under extreme heat conditions.Flame Application: Designed for versatility, our rods can withstand direct flame contact, making them ideal for various heating applications.
Glass-Like Fragility: While these rods mirror the fragility of glassware, they demand careful handling to maintain integrity.Handling Caution: Due to their delicate nature, meticulous handling is essential to prevent damage.
Permissible Fluxes: Enhance the functionality with appropriate fluxes:
such as potassium bisulfate (KHSO) and sodium pyrosulfate (NaSO), pre-dried at 212°C, are recommended.
Melting Point: Our rods demonstrate a formidable maximum melting temperature of 800°C, standing strong under intense heat.
Handling Precautions: Essential guidelines for maintaining rod performance and longevity.
Brittle Characteristics: Acknowledging their brittle nature, careful attention is necessary to keep these rods intact.Prevention of Breakage: Handle with precision and care to avert any potential breakage.
Cleaning Guidelines: Maintaining cleanliness to preserve rod efficiency.
Cleaning Methods: Employ suitable cleaning techniques using dilute inorganic acids (excluding HF).
Material Characteristics: Discover the robust features of our heating rods, tailored for optimal performance. Robust Structure: Hard yet fragile, our rods resist thermal shock and maintain form at elevated temperatures. Explore other distinctive physical properties:
Density: 3.2 g/cm³, reflecting a compact and solid composition.
Mohs Hardness: 9.5, showcasing exceptional hardness for demanding applications.
Specific Heat: 0.17 kcal/kg·°C, ensuring efficient heat absorption and retention.
Thermal Conductivity: 20 kcal/m·h·°C, allowing effective heat transfer for enhanced performance.
Linear Expansion Coefficient: 5×10 (m/°C), facilitating stability under temperature fluctuations.
Chemical Stability: With supreme resistance to acids, our SiC rods excel in chemical environments, although caution is advised with alkalis at high temperatures.
High-Temperature Reactions: Used continuously above 1000°C, these rods engage with oxygen and water vapor, undergoing specific reactions:
SiC + 2O → SiO + CO, illustrating its chemical adaptability.
SiC + 4HO → SiO + 4H + CO, maintaining performance while altering composition.
Aging Effect: These reactions boost SiO content, increasing resistance and contributing to the aging process.
Water Vapor Impact: Excess water vapor intensifies SiC oxidation, with resultant H reacting with O to perpetuate HO formation, a cycle that can reduce lifespan.
Nitrogen Influence: The presence of nitrogen (N) prevents SiC oxidation effectively below 1200°C, yet engages with SiC beyond 1350°C,leading to decomposition.
Chlorine Response: An encounter with chlorine (Cl) results in the total decomposition of SiC.
Fragility Alert: Due to their hard and brittle nature, these rods demand caution against impacts or vibrations during transport and use. Silicon carbide rods are hard and brittle-avoid strong impacts or vibrations during transport and handling.
Heating Zone Length: Ensuring alignment with the furnace chamber enhances safety and efficiency. The heating section should match the furnace chamber's width precisely to prevent damage.
Cold End Length: A strategic design for optimal performance. Ensure the cold end matches the furnace wall thickness and includes 50-150 mm of extension outside the wall, facilitating cooling and secure clamping.
Furnace Hole Diameter: Precision is key. Should be carefully calculated for optimal fit and performance. 1.4-1.6× Ensure the cold end's outer diameter is free from restrictions. Tight holes or filler materials can restrict thermal expansion, leading to potential breakage. Install rods with enough space for unhindered movement. 360° rotation.
Spacing Requirements:
Distance to heated materials/furnace wall: ≥ 3× heating zone diameter.
Center-to-center spacing between rods: ≥ 4× heating zone diameter.
Electrical Connection:Avoid loose connections; these increase contact resistance and heighten the risk of rod cracking.
Resistance Matching: Before use, ensure rods are grouped with similar resistance values.
Ensure: Use aluminum braids or foil to connect cold ends securely to the main circuit. Ensure clamps are firmly tightened.
Furnace Preheating: Preheat new or long-idle furnaces with old rods or alternative heat sources for optimal efficiency.
Storage: Keep rods dry. Moisture can degrade the cold end's aluminum layer,
Voltage Control: Utilize a voltage regulator. Begin at 50% of operating voltage, gradually increasing to prevent thermal shock.
Operating Limits:
Optimize surface load and temperature for ideal performance.
Max temperature: ≤1650°C.
Avoid chemical reactions in environments with corrosive gases.
Replacement: Replace rods with those of similar resistance or consider replacing the entire set. Partially used rods may be reused later if resistance remains suitable.
Avoid Molten Metal: Contact with molten metal results in breakage.
Avoid Alkalis: Alkali metals and oxides can corrode the rods, leading to damage.
Regular Checks: Consistently monitor amperage, voltage, and temperature. Inspect for the following:
Loose or oxidized clamps,
Rod fractures,
Uneven heating, indicated by red-hot zones.
| Property | Value |
|---|---|
| Bulk Density | 5.5 g/cm³ |
| Flexural Strength | 15-25 kg/cm² |
| Vickers Hardness | (HV) 570 kg/mm² |
| Porosity | 7.4% |
| Water Absorption | 1.2% |
| Thermal Elongation | 4% |
In high-temperature oxidizing atmospheres, silicon molybdenum rods develop a protective quartz (SiO) layer on the surface, effectively preventing further oxidation. When the element temperature surpasses 1700°C, this quartz layer melts. However, if continuous use in oxidizing atmospheres persists, the protective quartz layer will consistently regenerate.
Important Note: It is crucial to avoid using silicon molybdenum rods in the temperature range of 400-700°C for extended periods. This is because low-temperature oxidation during these conditions can result in the element becoming compromised and degrading into a powder form.
| Atmosphere | Continuous Use Temp. | Short-term Max Temp. |
|---|---|---|
| NO, CO, O, Air | 1700°C | 1800°C |
| He, Ar, Ne | 1650°C | 1750°C |
| SO | 1600°C | 1700°C |
| CO, N | 1500°C | 1600°C |
| Moist H | 1400°C | 1500°C |
| Dry H | 1350°C | 1450°C |
Silicon molybdenum (Si-Mo) rods, while demonstrating a slight softening at elevated temperatures (above 1500°C), tend to become hard and brittle at lower temperatures. To effectively manage thermal stress and account for thermal expansion and contraction, a free-hanging vertical installation is recommended. This approach not only mitigates stress but also facilitates the hot replacement of rods, allowing for swift changes without necessitating furnace cooling.
Furnace Lining Material
Use corundum bricks with an FeO content <1%. Higher FeO levels can interact with the protective SiO layer, producing low-melting silicates that expedite rod degradation.
Cold-End Sealing
Preventing hot gas leakage from cold ends is vital as it can increase heat loss and damage conductive clamps or leads. Asbestos clamps are recommended for optimal insulation.
Handling Fragility
Si-Mo rods are brittle with low flexural strength. It is imperative to avoid impacts during the installation process.
Secure asbestos/ceramic clamps prior to connecting conductive straps to ensure stability. Do not overtighten.
Mounting with Insulating Bricks
Use foamed corundum split bricks to house the rods, effectively minimizing mechanical stress during both installation and removal.
Furnace Roof Installation
Insert rod-mounted bricks into pre-cut furnace roof slots. Extend bricks beyond the roof surface to facilitate easier disassembly and maintenance access.
Conductive Strap Connection
Connect straps to the brackets that have been pre-installed. Avoid placing tension or unnatural bends on the straps to prevent undue stress and potential damage.
Anti-Sagging Measure
Apply refractory mortar (water glass-based) to the joints, ensuring asbestos clamps are fixed firmly to counteract any thermal expansion-induced drooping.
Positioning Clearances
Heating zone taper: Maintain a clearance of 25-30 mm from the furnace walls to ensure optimal performance.
Cold ends: Extend 75 mm above the furnace roof to allow for appropriate heat dissipation.
Lower heating end: Keep at least50 mm from the furnace floor to prevent excessive heat exposure.
Spacing Between Rods
Ensure The center-to-center distance exceeds the rod spacing specifications, ensuring optimal performance and structural integrity..
Achieve perfect gravity balance with our innovative design.
Expertly crafted with precise balance weight distribution, strategically placed at both the cold ends and wiring parts, this feature effectively prevents any bending of the heating section, safeguarding efficiency and durability.
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