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99.9% High-Purity Alumina Ceramic Protection Tube
99.9% high-purity alumina ceramic protection tube is made of ultra-high purity alumina powder through high-temperature precision sintering, belonging to high-purity corundum ceramic products. It features ultra-high temperature resistance, excellent oxidation resistance, strong insulation, corrosion resistance and high cleanliness without precipitation. It is mainly used for protection and isolation of temperature measuring elements, sensing components and electrodes under high-temperature conditions.Widely suitable for extreme high-temperature detection in metallurgy, heat treatment, semiconductor, chemical industry, glass manufacturing and other industries, it can effectively protect internal components from high-temperature oxidation, dust erosion, molten material scouring and corrosive gas damage, ensuring accurate temperature measurement, stable operation and prolonged service life.Application EnvironmentSuitable for air, inert gas, vacuum and other atmospheres; withstands long-term high temperature within 1600℃, resists high-temperature dust, corrosive flue gas, molten metal/glass splashing; ideal for static high-temperature measurement, continuous high-temperature monitoring and sensor protection in high-temperature furnaces; not suitable for long-term use in strong reducing atmosphere.
- Metallurgy Industry: Temperature measurement for molten steel, molten aluminum, thermocouple protection for heat treatment furnaces and annealing furnaces
- Semiconductor Manufacturing: Temperature tubes for high-temperature diffusion furnaces, CVD furnaces, annealing furnaces, no metal contamination in high-purity conditions
- Glass & Ceramic Industry: High-temperature detection and component protection for glass melting furnaces and ceramic sintering kilns
- Chemical Industry: Temperature measurement in high-temperature corrosive gas environment, sensor protection for high-temperature reactors
- Industrial Furnaces: Thermocouple protection tubes and temperature measuring sleeves for various high-temperature kilns, muffle furnaces and tube furnaces
Advantages
- Excellent Ultra-High Temperature Stability: No deformation, softening or oxidation weight loss during long-term use at 1600℃. Stable high-temperature structural strength ensures no deformation offset during temperature measurement, guaranteeing accurate data.
- Super Insulation Without Interference: Maintains ultra-high resistivity at high temperatures, eliminating leakage and signal interference. Suitable for precision temperature measurement and sensing equipment with stable and undistorted detection signals.
- High Cleanliness Without Contamination: 99.9% ultra-high purity, no impurity volatilization and no metal ion precipitation. Ideal for semiconductor, high-purity material sintering and other strict cleanliness scenarios without polluting tested materials.
- Corrosion & Erosion Resistance for Long Service Life: Resists high-temperature acid-base flue gas and molten splashing, not easy to corrode, wear or break. Greatly prolongs service life compared with ordinary ceramic and metal protection tubes, reducing replacement frequency and maintenance costs.
- Accurate Temperature Measurement & Reliable Response: Dense material with stable thermal conductivity, which can isolate harsh external environment and ensure accurate temperature transmission, realizing real-time, accurate and stable temperature monitoring under high-temperature conditions.
- Strong Oxidation Resistance & Long Lifespan: Excellent oxidation resistance in high-temperature aerobic environment, no surface oxidation, pulverization or cracking. Stable performance for long-term use, suitable for continuous production high-temperature detection scenarios.
Technical Parameters
- Alumina Purity: ≥99.9%
- Total Impurities: ≤100 ppm
- Bulk Density: ≥3.92 g/cm³
- Porosity: ≤0.05%
- Bending Strength: ≥450 MPa
- Long-term Service Temperature: 1600~1700℃
- Volume Resistivity: ≥10¹⁴ Ω·cm
- Product Characteristics: Ultra-long dimension, high straightness, uniform wall thickness, smooth inner wall
99.9% Alumina Ceramic vs Pressureless Sintered SiC Ceramic
Comparison for High-Temperature Applications
1. Core Performance Comparison Table
Performance Index 99.9% High-Purity Alumina Ceramic Pressureless Sintered SiC Ceramic Advantage Maximum Working Temperature Long-term ≤1600℃, short-term 1700℃ in air Long-term ≤1200℃ in air; rapid oxidation above 1300℃ Alumina High-Temperature Oxidation Resistance Excellent, stable at 1600℃ Fair; SiO₂ layer forms and peels off above 1300℃ Alumina Thermal Conductivity (25℃) 32–35 W/(m·K) 120–150 W/(m·K) SiC Thermal Expansion Coefficient 8.1×10⁻⁶/℃ 4.0×10⁻⁶/℃ SiC Thermal Shock Resistance Moderate, prone to cracking under large temperature difference Excellent, withstands rapid heating & cooling SiC Hardness (HV) 1800–2000 2500–2800 SiC Corrosion Resistance Resists most acids & alkalis (except HF & hot concentrated phosphoric acid) Extremely strong, resistant to most corrosive media SiC Electrical Insulation Excellent insulator at high temperatures Semiconductor, conductive at medium-high temperature Alumina Purity & Cleanliness 99.9% purity, low ion precipitation High purity but semiconductor property Alumina Cost Moderate Relatively high Alumina 2. Key Differences in High-Temperature Fields
High-temperature use in air atmosphere99.9% Al₂O₃ performs stably at 1600℃ without oxidation or deformation, ideal for high-temperature tubes and furnaces.Pressureless sintered SiC will oxidize severely above 1300℃, so it is not suitable for long-term service over 1200℃ in air.
High-temperature performance in vacuum / inert atmosphereBoth can withstand higher temperatures, while SiC retains higher strength at elevated temperatures.
Thermal shock resistanceSiC features low thermal expansion and high thermal conductivity, making it superior for frequent thermal cycling conditions.
3. Typical Application Selection
Recommended 99.9% Alumina Ceramic when:
- Working temperature exceeds 1300℃ in air
- High-temperature electrical insulation is required
- Ultra-clean, low-precipitation environment (semiconductor, pharmaceutical, analytical instruments)
- High-temperature furnace tubes, thermocouple protection tubes
Recommended Pressureless Sintered SiC Ceramic when:
- Severe wear and strong corrosion resistance needed (pumps, valves, seals)
- Frequent rapid heating and cooling cycles
- High thermal conductivity for heat dissipation components
- High-temperature structural parts in vacuum or inert atmosphere
- Above 1300℃ in air + insulation + high cleanliness → 99.9% Alumina
- Below 1200℃ + wear/thermal shock/corrosion resistance + high thermal conductivity → Pressureless Sintered SiC
4. Summary for Technical Selection
