| Customization: | Available |
|---|---|
| After-sales Service: | on-Line Service |
| Warranty: | 1 Years |
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Purpose:
The furnace tube serves as the inner lining of various experimental electric furnaces, primarily isolating the heating elements from the test materials, enclosing the heating zone, and holding the test substances. It is widely used in high-temperature testing and analytical instruments across industries such as coal testing, metallurgical powder analysis, and chemical/glass laboratory equipment.
Material & Manufacturing:
Corundum furnace tubes are mainly made of fused alumina, available in two types:
Ultra-fine powder-bonded
Clay-bonded
The specifications are customized based on user requirements, including 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 using high-temperature testing equipment, ensure gradual heating and cooling to minimize internal stress caused by thermal expansion/contraction. This reduces the risk of cracking and extends the tube's service life.
Composition:
Made of porous fused alumina, offering high durability and heat resistance.
Applications:
Suitable for melting samples with weak alkaline fluxes (e.g., anhydrous NaCO).
Not suitable for strong alkaline fluxes (e.g., NaO, NaOH) or acidic fluxes (e.g., KSO).
99.70% Corundum
Max short-term temperature: 1800°C
mechanical strength in oxidizing/reducing atmospheres.
High thermal conductivity, low thermal expansion.
Operating range: 1650-1700°C
Excellent high-temperature insulation &
Chemically inert to air, steam, H, CO, etc., up to 1700°C.
99.35% Corundum
Max short-term temperature: 1750°C
Operating range: 1600-1650°C
Stable in oxidizing/reducing atmospheres.
85.00% High-Alumina
Max short-term temperature: 1400°C
Operating range: 1290°C
Good insulation & mechanical strength in oxidizing/reducing atmospheres.
High thermal conductivity, low thermal expansion.
Chemically inert to air, steam, H, CO, etc.
Suitable for Experience the unparalleled endurance of our products with long-term use, designed to deliver reliable performance over extended periods. Our products excel under stable temperature conditions, ensuring consistent and optimal functionality.
Quartz glass tubes, meticulously crafted from silicon dioxide (SiO), represent a pinnacle of industrial technical glass, offering an exceptional foundation with a mesmerizing array of superior physical and chemical attributes, such as:
With an impressive softening point of approximately 1730°C,
our products are engineered for long-term use at temperatures reaching up to 1100°C, providing unmatched durability.
Even in short-term scenarios, they can withstand maximum temperatures of: 1450°C, showcasing their remarkable resilience.
Boasting near inertness to all acids, except for the formidable hydrofluoric acid (HF),our products exemplify exceptional durability.
With acid resistance that is:
a staggering 30 times that of traditional ceramics,
and a remarkable 150 times that of stainless steel, our offerings stand unparalleled.
Experience superior high-temperature chemical stability that remainsunmatched by any other engineering material, ensuring reliability in demanding conditions.
Featuring an extremely low thermal expansion coefficient,
these products withstand rapid temperature changes effortlessly, such as heating to 1100°C and immediate quenching in room-temperature water without any cracking or damage.
Our quartz glass offers outstanding light transmission across spectra spanning from ultraviolet to infrared,providing unparalleled clarity.
With visible light transmittance exceeding: 93%,
and UV spectrum transmittance reaching: up to an impressive 80%+, our products ensure superior optical performance.
Our products exhibit a resistivity that is: 10,000 times greater than that of ordinary glass,
maintaining exceptional insulation capabilities even at elevated temperatures.
Usage & Properties
Our crucibles are designed for use up to: 1450°C, and are available inboth transparent and opaque variants, allowing for versatile applications. Variants.
Advantages: Our products boast high purity, exceptional temperature resistance, impressive size with high precision, superior thermal insulation, energy-saving features, and consistent quality,packing a powerful advantage.
Chemical Compatibility
While our products do not interact with HF under standard conditions,
at elevated temperatures, they may react with caustic alkalis and alkali metal carbonates,requiring caution during use.
Suitable Fluxes
Our products are ideal for melting samples using potassium pyrosulfate (KSO) or potassium bisulfate (KHSO),ensuring optimal results.
Additionally, they can be effectively utilized with sodium pyrosulfate (NaSO), after pre-drying at 212°C, for thorough sample processing.
Quartz Crucible Usage & Maintenance
Primary Chemical Composition: Silicon Dioxide (SiO) - the essence of cutting-edge technology in heating elements.
These elements are remarkably resilient, remaining chemically inert against most acids (with the sole exception of HF), yet fully capable of reacting with caustic alkalis and alkali metal carbonates.
Outstanding Thermal Stability - these elements are engineered to withstand the highest temperatures.Versatility at Its Best - can be heated directly over a flame without concerns.
Delicate as Fine Glassware- Handle these precious components with the utmost care.
Permissible Fluxes:
Include KHSO (potassium bisulfate), NaSO (sodium pyrosulfate, pre-dried meticulously at 212°C), and more.
Maximum Melting Temperature: A robust 800°C.
Handling Precautions
Brittle and Fragile- Ensure careful manipulation to prevent any breaking incidents.
Cleaning
Easily maintained with dilute inorganic acids (excluding HF for safety).
Material Characteristics: Hard and brittle, these elements are masters of resisting thermal shock and laugh in the face of high temperatures, boasting these impressive physical properties:
Density: 3.2 g/cm³ - a testament to their sturdy nature.
Mohs Hardness: 9.5 - nearly as hard as diamond.
Specific Heat: 0.17 kcal/kg·°C - ensuring efficient energy usage.
Thermal Conductivity: 20 kcal/m·h·°C - perfect for heat transfer.
Linear Expansion Coefficient: 5×10 (m/°C) - stability in every dimension.
Silicon carbide rods possess extraordinary chemical stability, showing strong resistance to acids but making sure to avoid alkaline substances at elevated temperatures.
When used for extended periods above 1000°C, these rods engage in reactions with oxygen and water vapor:
SiC + 2O → SiO + CO
SiC + 4HO → SiO + 4H + CO
These reactions subtly increase SiO within the rod, gradually leading to augmented resistance and the inevitable march of aging.
Excessive water vapor prompts rapid SiC oxidation; the resulting H unites with O to regenerate HO, setting off a detrimental cycle that curtails rod longevity.
Nitrogen (N) guards against SiC oxidation under 1200°C but reacts with SiC beyond 1350°C, leading to decomposition.
Chlorine (Cl) renders SiC to total decomposition.
Fragility: Silicon carbide rods are inherently hard yet brittle - avoid any forceful impacts or vibrations during transportation and handling.
Heating Zone Length: Ensure the heating section is perfectly aligned with the furnace chamber's width. Extending into the furnace wall is a recipe for damage.
Cold End Length: Should mirror the furnace wall's thickness plus 50-150 mm for optimal cooling and clamping, extending just right outside the wall.
Furnace Hole Diameter: Must be precisely calculated for perfect fit. 1.4-1.6× Ensure the cold end's outer diameter is properly considered. Tight holes or filler materials can severely restrict thermal expansion, leading to potential breakage. It's crucial to install rods with care to allow for 360° rotation.
Spacing Requirements:
Maintain a safe distance to heated materials or the furnace wall: ≥ 3× the diameter of the heating zone.
Ensure center-to-center spacing between rods is at least: ≥ 4× the diameter of the heating zone.
Electrical Connection issues can increase contact resistance, escalating the risk of element cracking.
Resistance Matching: Before operational use, group rods that have similar resistance values.
ns: Utilize high-quality aluminum braids or foil to connect cold ends to the main circuit. Ensure all clamps are secure and tight.
Furnace Preheating: Preheat new or long-idle furnaces with old rods or alternative heat sources to ensure optimal performance.
Storage: Store rods in a dry environment. Exposure to moisture can degrade the cold end's aluminum layer.
Voltage Control: Employ a reliable voltage regulator. Begin at 50% of the operating voltage and gradually increase to prevent thermal shock.
Operating Limits:
Optimize surface load and temperature for best results.
Max temperature: ≤1650°C.
Avoid initiating chemical reactions, especially in corrosive gas environments.
Replacement: Replace rods only with those having similar resistance values or consider replacing the entire set. Partially used rods can be reused if their resistance remains suitable.
Avoid Molten Metal: Direct contact with molten metal can result in breakage.
Avoid Alkalis: Alkali metals and their oxides can corrode the rods, compromising integrity.
Regular Checks: Diligently monitor amperage, voltage, and temperature. Regularly inspect for issues such as:
Loose or oxidized clamps,
Rod fractures,
Uneven heating, particularly 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 that prevents further oxidation. However, when the element temperature exceeds 1700°C, this quartz layer melts. If used continually in oxidizing atmospheres, the protective quartz layer will regenerate, ensuring sustained protection.
Important Note: It is crucial to avoid using silicon molybdenum rods long-term within the 400-700°C temperature range. This condition promotes low-temperature oxidation, which gradually breaks down the element into powder form, compromising its integrity.
| 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 demonstrate a slight softening at high temperatures, particularly above 1500°C. However, at lower temperatures, they transition to a hard and brittle state. To effectively manage thermal stress and accommodate both thermal expansion and contraction, a free-hanging vertical installation is recommended. This innovative method also enables the hot replacement of rods without necessitating a complete furnace cool-down.
Furnace Lining Material
Use corundum bricks with FeO content <1%. A higher FeO content reacts detrimentally with the protective SiO layer, leading to the formation of low-melting silicates that significantly accelerate rod degradation.
Cold-End Sealing
Hot gas leakage from cold ends can result in increased heat loss and potential damage to conductive clamps and leads. Asbestos clamps are the preferred choice for effective insulation.
Handling Fragility
Si-Mo rods are brittle and possess low flexural strength. It is imperative to avoid any impacts during installation.
Secure asbestos/ceramic clamps prior to connecting the conductive straps. Do not overtighten.
Mounting with Insulating Bricks
Use foamed corundum split bricks to encase the rods, thereby minimizing mechanical stress during installation or removal.
Furnace Roof Installation
Insert rod-mounted bricks into pre-cut slots on the furnace roof. Extend bricks beyond the roof surface to facilitate easier disassembly.
Conductive Strap Connection
Connect straps to the pre-installed brackets with care. Avoid tension or unnatural bends to prevent undue stress.
Anti-Sagging Measure
Apply refractory mortar (water glass-based) to joints, securing asbestos clamps firmly to counteract drooping caused by thermal expansion.
Positioning Clearances
Heating zone taper: Maintain 25-30 mm away from furnace walls.
Cold ends: Extend 75 mm above the furnace roof to ensure safety.
Lower heating end: Keep at least50 mm from the furnace floor to optimize performance.
Spacing Between Rods
Ensure center-to-center distance is at least the rod spacing specifications.
Gravity Balance
Achieve optimal balance weight distribution at both the cold ends and wiring parts, ensuring stability and preventing any bending in the heating section.
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