Technical Characteristics of Alumina Tubes

Alumina tubes (main component Al₂O₃ ≥99%) are a type of high-performance ceramic material, widely used in high-temperature, corrosive environments, and precision industrial applications. Their main properties are as follows:

1. High-Temperature Resistance

Long-term working temperature: 1600℃
Maximum short-term tolerance temperature: 1800℃
Thermal shock resistance: withstands rapid cooling and heating (1550℃ water quenching 6 times without cracking)
Thermal expansion coefficient: 8.2×10⁻⁶/℃ (20–1000℃), with thermal stability superior to metals

2. Mechanical Strength

Compressive strength: ≥80 MPa (some products up to 350 MPa or even 12000 MPa)
Flexural strength: >350 MPa
Hardness: Mohs hardness 9 (second only to diamond and silicon carbide), with wear resistance more than 20 times that of carbon steel

3. Chemical Corrosion Resistance

Acid and alkali resistance: excellent resistance to most acids, bases, and molten salts (such as KOH, K₂CO₃) (though high-temperature molten alkalis may still cause corrosion)
Oxidation resistance: suitable for vacuum, inert, and reducing atmospheres

4. Physical Properties

Density: 3.80–3.95 g/cm³, porosity <1%, with high compactness
Thermal conductivity: 25 W/m·K, with excellent insulation performance (resistivity at 20℃ >10¹⁴ Ω·cm)
Dielectric constant: 2 (1 MHz), suitable for high-frequency insulation applications

5. Application Fields

High-temperature furnace tubes: vacuum tube furnaces, atmosphere furnaces (such as molybdenum wire furnaces, sintering furnaces)
Industrial measurement: thermocouple protection tubes, continuous steel temperature measurement
Wear-resistant pipelines: transportation of abrasive media in metallurgy and power industries
Special environments: chemical, military, and electronic industries requiring corrosion resistance

6. Specifications and Customization

Size range: inner diameter 0.5 mm to 150 mm, length up to 2500 mm
Custom options: can be processed into single-hole, multi-hole, threaded tubes, and other special structures

Conclusion:
Due to its ultra-high temperature resistance, mechanical strength, and chemical inertness, alumina tubes are an ideal substitute for quartz tubes (not resistant to alkali) and stainless steel (prone to oxidation at high temperatures), showing exceptional performance especially in extreme environments below 1800℃.