Precautions for selection of vacuum tube furnace

When choosing a vacuum tube furnace, the following precautions should be considered to ensure that the selected equipment can meet the specific needs of experiments or production:

1、 Temperature range and heating element
Temperature range:
Determine the temperature range of the furnace based on the highest and lowest temperatures required for the experiment or production process. For example, high-temperature ceramic sintering may require a tube furnace capable of reaching temperatures above 1800 ℃, while general metal heat treatment may only require equipment at around 1200 ℃.
To cope with possible temperature fluctuations and changes in future experiments, it is recommended to reserve a temperature margin of 100-200 ℃. For example, if the actual required temperature is 1200 ℃, choosing a tube furnace with a maximum temperature of 1400 ℃ is safer.
Heating element:
Common heating elements include resistance wires, silicon carbide rods, molybdenum wires (or silicon molybdenum rods), etc.
The cost of resistance wire is relatively low, but it is suitable for heating in the medium and low temperature range.
Silicon carbon rods can withstand higher temperatures and are suitable for heating in high-temperature ranges.
Molybdenum wire (or silicon molybdenum rod) is suitable for high temperature and special atmosphere requirements.
2、 Vacuum requirement
Choose the vacuum degree based on the strictness of the vacuum environment in the experiment or production process. For example, the preparation of semiconductor materials may require ultra-high vacuum levels of 10-4 Pa or even higher; And for some simple annealing treatments, a vacuum degree of 10-1 Pa may be sufficient.
3、 Furnace size
Heating zone length:
It determines the uniformity of heating of the sample. A longer heating zone can accommodate more or larger sized samples, ensuring uniform heating of the samples during the heating process.
For the quenching treatment of long rod-shaped materials, a longer temperature zone is required to ensure uniform and consistent structural transformation of the entire rod; For small-scale electronic component heating experiments, a shorter temperature range is sufficient.
Pipe diameter size:
Determine based on the size and quantity of the experimental samples. If a larger reaction vessel is used in the experiment or a large amount of material needs to be processed, a tube furnace with a larger diameter needs to be selected.
When conducting large-scale organic synthesis experiments, larger pipe diameters can ensure sufficient mixing of reactants and smooth reaction progress. However, for experiments with trace samples, a too large diameter is not conducive to the concentration and stable control of heat.
4、 Control accuracy and automation level
Control accuracy:
For processes that require temperature control, such as crystal growth, precision alloy processing, etc., a tube furnace with high temperature control accuracy should be selected, which can usually reach ± 1 ℃ or even higher.
Automation level:
If frequent operation of the same process is required, choosing a tube furnace with automatic temperature control, vacuum control, and program setting functions can improve work efficiency and accuracy.
5、 Furnace body material and structure
Furnace body material:
The stainless steel furnace body has good corrosion resistance and is suitable for most conventional applications.
If the material being processed has strong corrosiveness, it may be necessary to choose furnace bodies made of special materials such as quartz and corundum.
Furnace structure:
The horizontal tube furnace is easy to operate, with convenient loading, unloading, and observation of samples, making it suitable for most routine experiments and production operations.
The vertical tube furnace has a small footprint and is suitable for rapid heating or quenching processes. It also performs outstandingly in some special experiments, such as the growth experiment of thin film materials.
6、 Cooling method and safety
Cooling method:
A fast and effective cooling method can shorten the working cycle. Water cooling is usually faster than air cooling, but it is necessary to consider whether the laboratory has corresponding water cooling facilities and conditions.
Security:
Ensure that the tube furnace is equipped with safety devices such as over temperature protection, vacuum monitoring, and pressure protection to prevent accidents from occurring.
7、 Budget and after-sales service
Budget:
The prices of vacuum tube furnaces with different specifications and performance vary greatly. Reasonably control the budget while meeting the requirements. For example, small laboratories conducting routine annealing of metal materials have limited budgets and can choose tube furnaces with relatively lower prices; Large semiconductor manufacturing enterprises need to choose high-performance and high priced tube furnaces for processing high-purity silicon wafers.
after-sale service:
Brands are usually more guaranteed in terms of quality and performance. At the same time, good after-sales service can ensure timely resolution of equipment problems and reduce the impact on work.
8、 Other special needs
If special gases (such as hydrogen) need to be processed or high-temperature corrosion research needs to be conducted during the experimental process, it may be necessary to choose a tube furnace with special gas processing capabilities.
For certain specific processes, it may be necessary to choose a tube furnace with special features such as rotating design and multi temperature zone control.
In summary, when choosing a vacuum tube furnace, it is necessary to comprehensively consider multiple factors such as temperature range, vacuum requirements, furnace size, control accuracy, automation level, furnace material and structure, cooling method and safety, budget and after-sales service. By carefully evaluating these factors, it can be ensured that the selected equipment can meet the specific needs of the experiment or production.