High-temperature resistant alumina ceramic tubes high-purity Al₂O₃ insulation tubes

Alumina ceramic tubes are tubular ceramic products made from industrial alumina (Al₂O₃) through molding and high-temperature sintering. Performance varies significantly depending on the purity of the alumina (commonly available values from 95% to 99.9%). 

Higher purity results in better performance but also higher cost.

The performance of alumina ceramic tubes directly determines their application areas. Key features include:

• High hardness and excellent wear resistance: Alumina ceramics have a Mohs hardness of up to 9 (second only to diamond and silicon carbide), making them an ideal wear-resistant material and effectively resisting the impact of particles and fluids.
• High temperature resistance: Alumina ceramics can withstand long-term use in environments with temperatures up to 1600°C and can withstand short-term extreme temperatures up to 1800°C. They also offer excellent thermal stability and are not prone to deformation.
• Corrosion resistance: They offer excellent resistance to most acidic and alkaline media and organic solvents, are rust-resistant, and are resistant to oxidation.
• Excellent electrical insulation: They possess extremely high resistivity at both room and elevated temperatures, making them an excellent insulating material.
• High mechanical strength: They offer high compressive strength, but relatively low flexural strength and brittleness are drawbacks.
• Good chemical stability: does not react with most substances and has low pollution.

Performance Indicators	Unit	75% - 85% Alumina	95% - 96% Alumina	99% - 99.9% Alumina
Physical Properties
Alumina Content (Al₂O₃)	%	75 - 85	95 - 96	99 - 99.9
Color	-	Ivory White/Beige	White	White/Ivory
Density	g/cm³	3.4 - 3.6	3.6 - 3.75	3.8 - 3.95
Mechanical Properties
Rockwell Hardness (HRA)	-	80 - 85	85 - 87	88 - 90
Flexural Strength	MPa (20°C)	280 - 300	300 - 340	370 - 450
Compressive Strength	MPa	1200 - 1500	2000 - 2500	2500 - 3000
Fracture Toughness	MPa·m¹/²	3.0 - 3.5	3.5 - 4.0	4.0 - 4.5
Elastic Modulus	GPa	280 - 300	320 - 340	370 - 390
Thermal Properties
Max Use Temp	°C (In air)	1400 - 1500	1550 - 1650	1700 - 1800
Thermal Conductivity	W/m·K (20°C)	16 - 18	20 - 25	28 - 35
Coefficient of Thermal Expansion	×10⁻⁶/°C (20-500°C)	7.0 - 7.5	7.0 - 7.5	7.5 - 8.0
Thermal Shock Resistance	ΔT °C	180 - 200	200 - 220	200 - 230
Electrical Properties
Volume Resistivity	Ω·cm (20°C)	>10¹⁴	>10¹⁴	>10¹⁴
	Ω·cm (500°C)	10⁶ - 10⁷	10⁷ - 10⁸	10⁸ - 10⁹
Dielectric Strength	kV/mm	10 - 12	12 - 15	15 - 18
Dielectric Constant	@1MHz	8.0 - 8.5	9.0 - 9.5	9.5 - 10.0
Dielectric Loss	×10⁻⁴ @1MHz	3 - 5	2 - 4	1 - 3

Due to these properties, alumina ceramic tubes play an important role in various industrial fields:

1. High-Temperature and Heat Treatment Industry (Core Application)

• Kiln Tubes: Serving as tubes in muffle furnaces, atmosphere furnaces, and vacuum furnaces, they are used for heat treatment processes such as sintering, annealing, and brazing. They protect heating elements and create the required working atmosphere (such as inert gas).
• Thermocouple Protection Tubes: Enclose thermocouples, enabling them to be directly inserted into molten metal, salt baths, or other corrosive, high-temperature media for accurate temperature measurement.
• Glass Industry: Used as temperature measuring tubes for molten glass and sight glass tubes in glass melting furnaces.

2. Mechanical and Wear-Resistant Applications

• Wear-Resistant Lined Pipes: Lined inside metal pipes, they are used to transport highly abrasive materials such as pulverized coal, slurry, ash, and sand and gravel. Their service life is dozens of times longer than that of metal pipes.
• Guide Tubes and Sleeves: Used as guide rollers and bushings in mechanical design due to their wear resistance and low friction coefficient.

3. Electronics and Electrical Applications

• Insulating Porcelain Bushings: Used as insulating supports or protective casings in electrical equipment, sensors, and semiconductor manufacturing equipment (such as diffusion furnaces).
• Arc Tubes: Containers for the arc in high-intensity gas discharge lamps (such as metal halide lamps and high-pressure sodium lamps), they withstand high temperatures and chemical corrosion.

4. Chemical and Laboratory Applications

• Laboratory Equipment: Used as reaction tubes and combustion tubes in tube furnaces, as well as corrosion-resistant and high-temperature containers in laboratories.
• Chemical Pipelines: Pipelines or liners used to transport corrosive chemical media.

5. Other Applications

• Laser Components: Serves as the discharge tube of a CO₂ laser. Medical equipment: used for insulation and wear-resistant parts in some medical equipment.

Hunan Guoci Ceramics, leveraging its strong material R&D capabilities and advanced production processes, offers custom-made ceramic tubes such as alumina protective tubes, sleeves, and liners that are heat-resistant, wear-resistant, high-hardness, and insulated.

If you are looking for a reliable industrial ceramics manufacturer, please contact us for custom technical ceramic solutions.

Email: Marketing@guociceramic.com