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High-Quality Corundum Furnace Tube Crucible¹

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Product Description Corundum Furnace TubePurpose:The Corundum Furnace Tube is a pivotal component used as the inner lining of experimental electric furnaces. Its primary roles include isolating heating elements from test materials, enclosing the heating zone, and securely containing test substances. This tube is indispensable in high-temperature testing and analytical instruments, finding its applications in industries like coal testing, metallurgical powder analysis, and chemical/glass laboratory equipment.Material & Manufacturing:Crafted from superior fused alumina, Corundum furnace tubes come in two distinguished types:Ultra-fine powder-bondedClay-bondedThese tubes are meticulously customized to meet user specifications, including essential factors such as operating temperature, wear resistance, and protection against chemical corrosion.Dimensions:Outer diameter: 15-200 mmLength: 100-2000 mmWall thickness: 3-15 mmUsage Guidelines:To ensure optimal performance in high-temperature testing, it is crucial to maintain a gradual heating and cooling process which helps in reducing internal stress from thermal expansion/contraction. This practice significantly lowers the chance of cracking, thereby prolonging the service life of the tube.Corundum CrucibleComposition:Constructed from porous fused alumina, this crucible is renowned for its exceptional durability and remarkable heat resistance.Applications:It is ideally suited for melting samples in the presence of weak alkaline fluxes (such as anhydrous NaCO).Not suitable for exposure to strong alkaline fluxes (like NaO, NaOH) or acidic fluxes (such as KSO).Product Performance:99.70% CorundumMax short-term temperature: 1800°Cpossesses robust mechanical strength in both oxidizing and reducing atmospheres.Features high thermal conductivity and minimal thermal expansion.Operating range: 1650-1700°COutstanding high-temperature insulation &chemically inert to air, steam, hydrogen, carbon monoxide, etc., up to 1700°C.99.35% CorundumMax short-term temperature: 1750°COperating range: 1600-1650°CRemains stable in both oxidizing and reducing environments.85.00% High-AluminaMax short-term temperature: 1400°COperating range: 1290°COffers good insulation properties and mechanical strength in both oxidizing and reducing atmospheres.Boasts high thermal conductivity with low thermal expansion.Chemically inert to air, steam, hydrogen, carbon monoxide, etc.Suitable for long-term use under stable temperature conditions.Quartz Glass TubeQuartz glass tubes are a specialized industrial technical glass made from silicon dioxide (SiO), serving as an exceptional fundamental material. Quartz glass exhibits a series of outstanding physical and chemical properties, including:High-Temperature ResistanceSoftening point: ~1730°CLong-term use: Up to 1100°CShort-term maximum: 1450°CCorrosion ResistanceNearly inert to all acids except (HF).Acid resistance:30× that of ceramics150× that of stainless steelSuperior high-temperature chemical stability, unmatched by other engineering materials.Thermal StabilityExtremely low thermal expansion coefficient.Withstands rapid temperature changes (e.g., heating to 1100°C and quenching in room-temperature water without cracking).Optical TransparencyExcellent light transmission across UV to infrared spectra.Visible light transmittance: >93%UV spectrum transmittance: Up to 80%+Electrical InsulationResistivity: 10,000× higher than ordinary glass.Maintains superb insulation even at high temperatures.Quartz CrucibleUsage & PropertiesCan be used up to 1450°C, available in transparent and opaque variants.Advantages: High purity, excellent temperature resistance, large size with high precision, good thermal insulation, energy-saving, and stable quality.Chemical CompatibilityNot compatible with HF .At high temperatures, reacts easily with caustic alkalis and alkali metal carbonates.Suitable FluxesIdeal for melting samples using KSO (potassium pyrosulfate) or KHSO (potassium bisulfate).Can also be used with NaSO (sodium pyrosulfate, pre-dried at 212°C) for sample processing.Quartz Crucible Usage & MaintenancePrimary chemical composition: Silicon dioxide (SiO).Our New RJ Corundum Furnace Tube Crucible is remarkably resilient, standing chemical attacks from most acids except the notorious hydrofluoric acid (HF). However, it does interact with caustic alkalis and alkali metal carbonates.Exhibiting superior thermal stability, this crucible withstands high temperatures without compromising its integrity.Capable of being directly heated over an open flame, our crucible offers unmatched versatility for various heating applications.Designed with an exquisite glassware-like structure, it's as fragile as it is functional.Due to its delicate nature, careful handling is essential to maintain its pristine condition.Compatible Fluxes:Our crucible is compatible with fluxes such as potassium bisulfate (KHSO) and sodium pyrosulfate (NaSO), pre-dried at 212°C.The crucible boasts an impressive maximum melting temperature of 800°C, perfect for high-temperature applications.Essential Handling GuidelinesAs it is both brittle and fragile,exercise utmost care during handling to avoid accidental breakage.Cleaning ProtocolOur crucible can be efficiently cleaned using dilute inorganic acids, with the exception of HF,ensuring longevity and performance.Material Characteristics Overview: Our crucible is hard and brittle, resistant to thermal shock, and maintains its form at elevated temperatures. Delve into its physical properties:Density: 3.2 g/cm3 - offering substantial weight and durability.Mohs Hardness: 9.5 - indicative of its impressive scratch resistance.Specific Heat: 0.17 kcal/kg·°C - ensuring efficient thermal management.Thermal Conductivity: 20 kcal/m·h·°C - delivering excellent heat distribution.Linear Expansion Coefficient: 5×10 (m/°C) - showcasing minimal expansion at high temperatures.Chemical CharacteristicsSilicon carbide rods boast exceptional chemical stability and robust resistance to acids. However, note that alkaline substances may corrode them at elevated temperatures.When employed at temperatures exceeding 1000°C, silicon carbide rods interact with oxygen and water vapor resulting in:SiC + 2O → SiO + CO - increasing SiO content and resistance.SiC + 4HO → SiO + 4H + CO - a gradual alteration increasing resistance and aging.These reactions can enhance SiO content, raising resistance and accelerating aging.Excessive water vapor can accelerate SiC oxidation; H produced may react with O, reformulating HO, creating a vicious cycle shortening the rod's lifespan.Nitrogen (N) protects SiC from oxidation below 1200°C but reacts with SiC beyond 1350°C,decomposing it.Chlorine (Cl) entirely decomposes SiC, necessitating cautious handling.Usage GuidelinesFragility Concerns: Given the hard yet brittle nature of silicon carbide rods, avoid any strong impacts or vibrations during transport and handling.Optimal Heating Zone: Align the heating section with the furnace chamber's width. Extending it into the furnace wall may compromise structural integrity.Appropriate Cold End Length: Ensure the cold end matches the furnace wall thickness plus 50-150 mm for optimal cooling and secure clamping.Furnace Hole Diameter Specification: The diameter should be 1.4-1.6× Ensure the cold end's outer diameter is properly accounted for. Restrictive holes or filler materials may limit thermal expansion, leading to potential breakage. It's essential to install rods in a manner that accommodates this expansion. Experience seamless 360° rotation.Spacing Requirements:Maintain a safe distance from heated materials or the furnace wall: ≥ 3× the heating zone's diameter for optimal performance.Ensure the center-to-center spacing between rods is at least: 4× the heating zone's diameter, ensuring uniform heat distribution.Electrical ConnectionEnhance safety by minimizing contact resistance to reduce the risk of cracking.Resistance Matching: For optimal use, group rods with similar resistance valuesto ensure uniform performance.Connections: Utilize high-quality aluminum braids or foil to connect cold ends securely to the main circuit. Ensure all clamps are tightly fastened for maximum efficiency.Furnace Preheating: Carefully preheat new or long-idle furnaces using either old rods or alternative heat sources to avoid thermal shock.Storage: Store rods in a dry environment. Moisture can degrade the aluminum layer at the cold end, compromising performance.Voltage Control: Implement a voltage regulator to carefully start at 50% of the operating voltage. Gradually increase this to avoid thermal shock and ensure longevity.Operating Limits:For optimal results, surface load and temperature must be carefully managed.Maximum allowable temperature is: ≤1650°C. Ensure this limit is respected to prevent damage.Avoid chemical reactions, especially within corrosive gas environments, to maintain integrity.Replacement: When replacing rods, use those with similar resistance or consider replacing the entire set. Partially used rods may be reused later, provided their resistance is still suitable.Avoid Molten Metal: Contact with molten metal can lead to breakage; ensure precautions are taken.Avoid Alkalis: Alkali metals and oxides can cause corrosion to the rods, so avoidance is crucial.Regular Checks: Routinely monitor amperage, voltage, and temperature levels. Inspect for issues including:Loose or oxidized clamps,Rod fractures,and uneven heating leading to red-hot zones; address promptly to maintain efficiency.Main Applications:The Silicon molybdenum (Si-Mo) heating elements are invaluable in industries such as metallurgy, steelmaking, glass, ceramics, refractory materials, and more. They play a crucial role in the production of high-performance precision ceramics, synthetic crystals, structural cermets, fiberglass, optical fibers, and premium alloy steels, driving innovation and quality across fields.PropertyValueBulk Density5.5 g/cm3Flexural Strength15-25 kg/cm2Vickers Hardness(HV) 570 kg/mm2Porosity7.4%Water Absorption1.2%Thermal Elongation4%Chemical Properties of Silicon Molybdenum RodsIn high-temperature oxidizing atmospheres, silicon molybdenum rods develop a protective quartz (SiO) layer, serving as a shield against further oxidation. Surpassing 1700°C, this layer melts but will regenerate in continued oxidizing conditions, ensuring sustained protection and longevity of the material.Important Notice: Be cautious when using silicon molybdenum rods within the temperature range of 400-700°C, as prolonged exposure in this range can lead to low-temperature oxidation, transforming the element to a powdery state.Understanding Maximum Operating Temperatures Across Various AtmospheresAtmosphereContinuous Use Temp.Short-term Max Temp.NO, CO, O, Air1700°C1800°CHe, Ar, Ne1650°C1750°CSO1600°C1700°CCO, N1500°C1600°CMoist H1400°C1500°CDry H1350°C1450°CEssential Installation Precautions for Silicon Molybdenum RodsSilicon molybdenum (Si-Mo) rods display slight softening when exposed to temperatures exceeding 1500°C. However, at lower temperatures, they become hard and brittle. To effectively reduce thermal stress and accommodate the natural expansion and contraction due to temperature changes, it is advisable to utilize a free-hanging vertical installation approach. This method enhances the ease of hot replacement of rods, eliminating the need to cool down the furnace before changing rods.Critical Installation Guidelines to Follow:Furnace Lining Material SelectionOpt for corundum bricks featuring FeO content less than 1%.Excessive FeO presence can interact with the protective SiO layer, leading to the formation of low-melting silicates, which hasten rod deterioration.Cold-End Sealing MeasuresLeakages of hot gas from cold ends can result in increased heat loss and potential damage to conductive clamps or leads. It is recommended to use asbestos clamps for effective insulation.Handling the Brittle Nature of Si-Mo RodsSilicon molybdenum rods are inherently brittle and possess low flexural strength. Take care to avoid any impacts during the installation process.Ensure that asbestos or ceramic clamps are securely fastened before proceeding to connect conductive straps. Avoid excessive tighteningto maintain integrity.Mounting with Insulating Bricks for ProtectionSelect foamed corundum split bricks to encase rods, effectively reducing mechanical stress during both installation and removal.Furnace Roof Installation MethodologyCarefully insert rod-mounted bricks into the designated pre-cut slots on the furnace roof. Ensure the bricks extend beyond the roof surface to facilitate easier disassembly when required.Connection of Conductive StrapsSecurely connect straps to the pre-installed brackets. Prevent any tension or unnatural bends to avoid undue stress and potential damage.Implementing Anti-Sagging MeasuresEmploy refractory mortar, specifically water glass-based,for joint application, ensuring asbestos clamps are firmly fixed to counter the sagging caused by thermal expansion.Ensuring Proper Positioning ClearancesHeating zone taper specifications: Maintain a clearance of 25-30 mm from the furnace walls.Cold ends: Ensure they extend 75 mm above the furnace roof for optimal performance.Positioning the Lower Heating End: Maintain a distance of at least50 mm from the furnace floor to prevent heat damage.Spacing Considerations Between RodsEnsure the appropriate distance is maintained to avoid thermal interference and ensure efficient operation. The innovative design of our product ensures a center-to-center distance that surpasses the rod spacing specifications, providing optimal performance..Gravity BalanceOur cutting-edge technology focuses on the precise balance weight distribution at both the cold ends and wiring sections to effectively prevent any bending of the heating section, ensuring durability and reliability.

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