| Customization: | Available |
|---|---|
| After-sales Service: | on-Line Service |
| Warranty: | 1 Years |
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Purpose:
Our Corundum Furnace Tube is an essential component in the realm of experimental electric furnaces. Meticulously designed to serve as the inner lining, it acts as a robust shield for the heating elements, effectively isolating them from the test materials. This innovative tube encloses the heating zone and safely cradles the test substances, making it an indispensable asset for high-temperature testing and analytical instruments. Widely acclaimed across diverse sectors, including coal testing, metallurgical powder analysis, and chemical/glass laboratory equipment, it stands as a testament to superior engineering.
Material & Manufacturing:
Our corundum furnace tubes are crafted from the finest fused alumina, offered in two distinct types:
Ultra-fine powder-bonded
Clay-bonded
Each tube is tailor-made to meet specific user requirements, ensuring optimum performance in operating temperature, wear resistance, and chemical corrosion resistance.
Dimensions:
Outer diameter ranging from 15 to 200 mm.
Length options vary from 100 to 2000 mm.
Wall thickness available between 3 and 15 mm.
Usage Guidelines:
For optimal use of high-temperature testing equipment, it is imperative to gradually heat and cool the equipment to minimize the internal stress inflicted by thermal expansion and contraction. This practice significantly reduces the risk of cracking, thereby extending the tube's service life.
Composition:
Crafted from high-grade porous fused alumina, this crucible boasts remarkable durability coupled with exceptional heat resistance.
Applications:
It is perfectly suited for melting samples in the presence of weak alkaline fluxes such as anhydrous NaCO.
However, it is not suitable for strong alkaline fluxes (e.g., NaO, NaOH) or acidic fluxes (e.g., KSO).
With a composition of 99.70% Corundum, this product ensures top-tier performance.
It can withstand a maximum short-term temperature of 1800°C,
offering robust mechanical strength even in oxidizing and reducing atmospheres.
Its high thermal conductivity coupled with low thermal expansion makes it a stellar choice.
Operating range: Ideally functions between 1650 to 1700°C,
providing excellent high-temperature insulation and
remaining chemically inert to air, steam, hydrogen, carbon monoxide, etc., up to 1700°C.
99.35% Corundum
This variant can endure a maximum short-term temperature of 1750°C.
Operating range: 1600 to 1650°C,
ensuring stable performance in oxidizing and reducing environments.
85.00% High-Alumina
Supports a maximum short-term temperature of 1400°C,
with an operating range around 1290°C.
Delivers reliable insulation and mechanical strength within oxidizing and reducing atmospheres,
offering high thermal conductivity and low thermal expansion.
Its chemical inertness makes it resistant to air, steam, hydrogen, carbon monoxide, and more.
Perfectly Engineered for extended-lasting performance amidst unwavering temperature environments.
Quartz glass tubes are a highly specialized industrial technical material crafted from silicon dioxide (SiO), renowned for their exceptional properties. This glass offers unparalleled physical and chemical characteristics, highlighted by:
Softening point reaching approximately 1730°C
Designed for prolonged operation at temperatures up to 1100°C
Capable of withstanding maximum short-term temperatures of: 1450°C
Virtually inert against all acids except hydrofluoric acid (HF).
Exhibits acid resistance
30 times greater than ceramics and
150 times superior to that of stainless steel
Extraordinary high-temperature chemical stability, outperforming all other engineering materials.
Boasts an extremely low thermal expansion coefficient.
Effortlessly withstands quick temperature alterations (such as heating to 1100°C and rapid cooling in water without fracturing).
Offers outstanding light transmission across the UV to infrared spectra.
Visible light transmittance of: greater than 93%
UV spectrum transmittance reaching: up to 80%+
Exhibits resistivity: 10,000 times higher than standard glass.
Retains excellent insulation capabilities even at elevated temperatures.
Application & Characteristics
Suitable for use at temperatures up to 1450°C, available in both transparent and opaque forms.
Key Advantages: High purity, remarkable temperature endurance, large dimensions with high precision, excellent thermal insulation, energy-efficient, and reliable quality.
Chemical Compatibility
Unsuitable for use with HF .
At elevated temperatures, reacts readily with strong alkalis and alkali metal carbonates.
Optimal Fluxes
Ideal for melting samples using potassium pyrosulfate (KSO) or potassium bisulfate (KHSO).
Compatible with sodium pyrosulfate (NaSO, pre-dried at 212°C) for effective sample processing.
Quartz Crucible Usage & Maintenance
Primary chemical composition: Silicon dioxide (SiO). This forms the robust foundation of the state-of-the-art Low Noise Molybdenum Disilicide Heating Elements by RJ, offering unparalleled performance.
RJ's heating elements are chemically resilient, remaining inert against most acids (barring HF), but they're reactive with caustic alkalis and alkali metal carbonates. This ensures their longevity and adaptability in diverse environments.
Boasting excellent thermal stability, these heating elements maintain their structure and efficacy even under intense thermal conditions, ensuring reliable performance during continuous operation.Engineered for versatility, these elements can be directly heated over a flame, providing flexibility across various heating applications.
Fragile like exquisite glassware, these elements require the same level of care and attention to maintain their pristine condition and optimal performance.Due to their delicate nature, careful handling is imperative to prevent damage and ensure the longevity of the heating elements.
Permissible fluxes for optimal performance include::
KHSO (potassium bisulfate) and NaSO (sodium pyrosulfate, pre-dried at 212°C) are recommended for use to achieve optimal chemical reactions without compromising the integrity of the heating elements.
Maximum melting temperature: 800°C. This high threshold ensures that RJ's heating elements perform consistently and efficiently in demanding thermal environments.
Handling Precautions: Ensure careful handling to maintain the structural integrity and performance of these advanced heating elements.
Brittle and fragile, these elements require meticulous handling to prevent breakage and maintain their high-performance standards.-handle with care to avoid breakage. This attention to detail ensures the longevity and durability of the heating elements.
Cleaning: To maintain their pristine condition and functionality, clean these elements with suitable solutions.
Can be cleaned with dilute inorganic acids (except HF). This careful cleaning regime ensures the elements remain in peak condition without compromising their structure..
Material Characteristics: the exceptional qualities designed for high performance and durability. Hard, brittle, and resistant to thermal shock, these elements maintain stability and do not easily deform at elevated temperatures. Their physical prowess is further delineated by the following attributes:
Density: 3.2 g/cm³ - This density ensures robust structural integrity across various operational conditions.
Mohs Hardness: 9.5 - A testament to their durability and resistance to wear and tear during regular use.
Specific Heat: 0.17 kcal/kg·°C - Facilitates efficient heat management and energy consumption.
Thermal Conductivity: 20 kcal/m·h·°C - Ensures rapid and uniform heat distribution, enhancing process efficiency.
Linear Expansion Coefficient: 5×10 (m/°C) - Guarantees dimensional stability under thermal strain.
While these rods offer impressive chemical stability, they are susceptible to corrosion by alkaline substances at elevated temperatures, necessitating careful operational planning.
When used long-term above 1000°C, silicon carbide rods react with environmental elements, resulting in: 1000°C, silicon carbide rods react with oxygen and water vapor as follows, impacting their longevity:
SiC + 2O → SiO + CO - This reaction gradually alters the rod's composition, demanding attention to mitigate resistance increase and aging.
SiC + 4HO → SiO + 4H + CO - Ongoing reactions contribute to rising SiO content, thereby increasing resistance and accelerating aging.
These reactions gradually increase the SiO content in the rod, leading to higher resistance and aging. Such changes necessitate proactive management to sustain performance.
Excessive water vapor accelerates SiC oxidation, creating a detrimental cycle that compromises the rod's lifespan and performance.
Nitrogen (N) acts as a protective shield, preventing SiC oxidation below 1200°C, thus preserving the material's integrity. prevents SiC oxidation below 1200°C but reacts with SiC above 1350°C, leading to decomposition and necessitating operational caution to prevent material degradation. 1350°C, decomposing it.
Chlorine (Cl) is known to completely decompose SiC, thus extreme care must be taken to avoid exposure. completely decomposes SiC.
Fragility: Silicon carbide rods are hard and brittle. Avoid strong impacts or vibrations to preserve their structural integrity. Silicon carbide rods are hard and brittle-avoid strong impacts or vibrations during transport and handling. This preserves their optimal functionality and extends their lifespan.
Heating Zone Length: Ensure the heating section corresponds to the furnace chamber's width, avoiding wall damage and optimizing performance. The heating section should match the furnace chamber's width. Extending it into the furnace wall may damage the wall.
Cold End Length: For effective cooling and clamping, ensure the cold end aligns with the furnace wall thickness plus an additional 50-150 mm of extension. The cold end should equal the furnace wall thickness plus 50-150 mm of extension outside the wall for cooling and clamping.
Furnace Hole Diameter: Ensure precision in furnace hole specifications to promote seamless integration and optimal performance of the heating elements. Ensure the installation process accounts for thermal expansion to avoid any breakage. The installation should allow for an outer diameter of 1.4-1.6× the cold end. Avoid tight holes or filler materials that may restrict this expansion. 1.4-1.6× the cold end's outer diameter. Tight holes or filler materials can restrict thermal expansion, causing breakage. Install rods to allow Ensure a 360° rotation capability, enhancing the operational flexibility and longevity of the equipment..
Spacing Requirements:
Maintain a safe distance to heated materials and furnace walls, ensuring it is at least 3× the diameter of the heating zone for optimal performance and safety.
Ensure that the center-to-center spacing between rods is no less than 4× the diameter of the heating zone to maintain functional efficacy and safety.
Electrical Connections:Avoid increasing contact resistance or risk of cracking by ensuring connections are secure and resistance is low.
Resistance Matching: Group rods meticulously, selecting those with similar resistance valuesto ensure uniform heating and prolong rod lifespan.
Connections: Utilize high-quality aluminum braids or foil for secure connection of cold ends to the main circuit, ensuring clamps are firmly tightened to prevent slippage.
Furnace Preheating: For optimal performance, preheat new or long-idle furnaces using old rods or other heat sources, ensuring a gradual increase in temperature.
Storage: To maintain integrity, keep rods in a dry environment, as moisture can degrade the aluminum layer of the cold end.
Voltage Control: To prevent thermal shock, initiate operations with a voltage regulator starting at 50% of the operating voltage, and then gradually increase to the desired level.
Operating Limits:
Optimize surface load and temperature to ensure the best performance.
Max temperature: Keep operations at or below ≤1650°Cto prevent damage and maintain functionality.
Avoid usage in corrosive gas environments to prevent detrimental chemical reactions.
Replacement: For consistent performance, replace rods with those of similar resistance or consider replacing the entire set. Partially used rods, if suitable in resistance, can be reused effectively.
Avoid Molten Metal: Protect rods from contact with molten metal to prevent potential breakage.
Avoid Alkalis: Prevent exposure to alkali metals and oxides as they can corrode the rods, compromising their longevity.
Regular Checks: Conduct routine checks on amperage, voltage, and temperature. Be vigilant for:
Loose or oxidized clamps,
Rod fractures,
and any signs of uneven heating, such as 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 environments, silicon molybdenum rods form a protective quartz (SiO) layer on their surface, safeguarding against further oxidation. When temperatures exceed 1700°C, this quartz layer melts, but remarkably regenerates when continued use occurs in oxidizing conditions.
Important Note: It is crucial to avoid long-term usage of silicon molybdenum rods within the 400-700°C range. This is because low-temperature oxidation can lead to the degradation of the element, turning it into powder form. Protect your investment by monitoring temperature ranges diligently.
| 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 are known for their slight softening at extremely high temperatures, specifically above 1500°C. However, at lower temperatures, these rods become hard and brittle. To effectively minimize thermal stress and accommodate the natural thermal expansion and contraction process, a free-hanging vertical installation is recommended. This innovative method also enables hot replacement of rods, eliminating the need to wait for the furnace to cool down, saving you valuable time.
Furnace Lining Material
Use corundum bricks with FeO content <1%. This is essential because higher FeO levels can react with the protective SiO layer, forming low-melting silicates that significantly accelerate rod degradation, compromising performance and longevity.
Cold-End Sealing
Prevent hot gas leakage from cold ends as it increases heat loss and potentially damages the conductive clamps and leads. To ensure optimal insulation, use asbestos clamps for superior performance and reliability.
Handling Fragility
Si-Mo rods are brittle with low flexural strength. It is important to avoid any impacts during installation to maintain their integrity.
Secure asbestos/ceramic clamps prior to connecting conductive straps. Do not overtightenas this may cause damage.
Mounting with Insulating Bricks
Use foamed corundum split bricks to securely house rods, minimizing mechanical stress during both installation and removal, thereby prolonging their service life.
Furnace Roof Installation
Insert rod-mounted bricks into the pre-cut slots of the furnace roof. Ensure bricks extend beyond the roof surface for easier access and disassembly when needed.
Conductive Strap Connection
Connect straps to the pre-installed brackets. Avoid tension or unnatural bends to prevent any undue stress that could compromise the system.
Anti-Sagging Measure
Apply refractory mortar (water glass-based) at the joints to firmly secure the asbestos clamps and counteract any sagging induced by thermal expansion, ensuring stability.
Positioning Clearances
Heating zone taper: Maintain 25-30 mm from furnace walls to ensure optimal performance and safety.
Cold ends: Extend 75 mm above the furnace roof, allowing for efficient heat dissipation.
Lower heating end: Keep ≥50 mm from the furnace floor to prevent overheating and ensure reliable operation.
Spacing Between Rods
Ensure Center-to-Center Distance: With a focus on precision and efficiency, our low noise molybdenum disilicide heating elements feature an optimal center-to-center distance that meets or exceeds rod spacing specifications, ensuring superior performance and reliability.Discover the exceptional engineering behind our heating elements.
Gravity Balance: Our innovative design incorporates advanced gravity balance technology,
ensuring meticulous balance weight distribution at strategic points, including both cold ends and wiring parts, to effectively prevent any bending of the heating section, thus enhancing durability and longevity.
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