How to choose the material of high-temperature tube furnace tube, the difference between quartz tube and corundum tube

Choosing a high-temperature tube furnace, the furnace tube is the core component that directly determines the upper limit of equipment temperature resistance, atmosphere adaptability, experimental stability, and service life. Many university laboratories and users of new material research and development are torn between choosing quartz tubes or corundum tubes for tube furnace tubes? There is no absolute superiority or inferiority between the two, the core depends on the process temperature, atmosphere type, material system, and experimental requirements. Below, we will compare the differences between the two in detail and provide a clear selection idea for everyone.

A commonly used small mini desktop tube furnace (click on the image to view product details)

1. Introduction to two types of furnace tube foundations
Quartz tube: Made of fused silica (SiO ₂), it belongs to special quartz glass and is transparent throughout. It is a commonly used furnace tube in laboratory tube furnaces.
Corundum tube (alumina tube): generally refers to high-purity alumina ceramic tube, made of white or light pink opaque ceramic material, and is the mainstream choice for high-temperature processes above 1200 ℃.

2. Comparison of core performance differences
(1). Temperature resistance
The recommended long-term safe use temperature for quartz tubes is ≤ 1100 ℃, and the maximum short-term temperature should not exceed 1200 ℃. After exceeding the temperature, quartz will soften, crystallize, and become opaque and deformed; In a vacuum environment, the upper limit of temperature resistance will further decrease.
Corundum tubes have obvious advantages in high temperature resistance. High purity corundum tubes can be stably used for a long time up to 1500-1600 ℃, and can withstand high temperatures of 1700 ℃ in a short time. Corundum furnace tubes are basically standard for high-temperature tube furnaces at 1400 ℃ and 1600 ℃.
(2). Transparency and Visibility
Quartz tubes are transparent and can directly observe the state, color changes, and reaction processes of samples inside the furnace with the naked eye. They are suitable for CVD, pyrolysis, and sample observation experiments.
Corundum tubes are opaque ceramics that cannot observe internal samples, making them suitable for processes that do not require visual observation and mainly rely on high-temperature sintering.
(3). Thermal shock resistance performance
Quartz tubes have a low coefficient of thermal expansion, excellent thermal shock resistance, support fast heating and cooling rates, and are not easily cracked during rapid cooling and heating;
Corundum ceramics are more prone to cracking due to rapid heating and cooling, as well as thermal shock, compared to quartz. It is recommended to slow down the heating and cooling rate during use to avoid rapid introduction of cold gas for cooling.
(4). Chemical corrosion resistance, atmosphere adaptation
Quartz tubes are resistant to most strong acids, but not to hydrofluoric acid (HF), high-temperature strong alkalis, and alkali metal oxides. They will react and corrode with alkaline materials at high temperatures; Suitable for air, inert gas, weak oxidizing atmosphere, and use with caution in some reducing atmospheres.
Corundum tubes have stronger chemical stability, are resistant to acid and alkali, and most high-temperature atmospheres. They have good stability under oxidizing and inert atmospheres; But it should also not come into contact with hydrofluoric acid, as strong alkali can slowly corrode the alumina substrate in a long-term high-temperature environment.
(5). Wear resistance and mechanical strength
Corundum ceramics have high hardness, wear resistance, and good bending strength. Powder materials and particle samples are not easily scratched by friction, making them suitable for rotary tube furnaces and continuous powder sintering conditions;
Quartz has a brittle texture, and the powder is prone to scratching and scratching after long-term erosion. It is more prone to fragmentation under vibration and rotation conditions, making it unsuitable for long-term powder friction scenarios.
(6). cost price
Under the same specifications, the price of quartz tubes is lower, and the cost of procurement and replacement is cheaper; High purity corundum tubes have complex raw materials and firing processes, and are priced higher than quartz tubes.

3. Which process scenarios are suitable for each
✅ Prioritize quartz tubes
-Working temperature ≤ 1100 ℃;
-Real time observation of sample reaction status is required, CVD、 Gas deposition and pyrolysis experiments;
-Need for rapid temperature rise and fall, frequent rapid cooling and heating;
-Teaching experiments, conventional annealing, low-temperature atmosphere heat treatment, limited budget;
-The sample does not contain strong alkali or fluoride.

✅ Prioritize choosing corundum pipes
-Process temperature above 1200 ℃, high-temperature sintering at 1300-1600 ℃;
-High temperature sintering of ceramic powders, hard alloys, and magnetic materials;
-Powder materials and granular materials are continuously fed into a rotary tube furnace;
-No need to observe the sample, pursue long-term stability at high temperatures;
-Long term high-temperature oxidation and inert atmosphere heat treatment.

4. Key points for selecting and avoiding pitfalls
(1). Don’t just look at the nominal temperature of the furnace. If your process is above 1200 ℃ for a long time, even if you use quartz tubes, they are prone to deformation and scrap. Choose corundum tubes directly;
(2). If the material contains alkali metals, hydrofluoric acid system, quartz and ordinary corundum are not suitable, other materials such as silicon carbide and special alloys need to be considered for furnace tubes;
(3). Corundum tubes vary greatly in purity, temperature resistance, and purity. When sintering high-purity materials, high-purity corundum tubes must be selected to reduce impurity contamination of the sample;
(4). Attention should be paid to vacuum working conditions: quartz is more prone to crystallization under high vacuum and high temperature, and high-temperature vacuum sintering prioritizes corundum tubes;
(5). When replacing furnace tubes, the materials of flange seals and sealing rings should also be synchronized with the temperature to avoid premature aging and leakage of seals.

Small vacuum tube furnace (click on the picture to view product details)

5. Conclusion
Summary of selection in a simple sentence: within 1100 ℃, depending on the sample, fast heating, choose quartz tube; High temperature sintering above 1200 ℃, powder process, no need to look at samples, choose corundum tube.
The material of the high-temperature tube furnace directly affects the success rate of the experiment. When customizing a tube furnace, the process temperature, atmosphere, and material composition can be synchronized with the manufacturer, who can match the more suitable tube material. It can also support the switching of multiple different material tubes for backup use in one furnace.Click to learn more tube furnaces! Or click on online customer service to learn more about product information!