What are the advantages and disadvantages of heating elements in vacuum tube furnaces?

The advantages and disadvantages of heating elements in vacuum tube furnaces are analyzed as follows:

resistance wire
advantage:

Low cost: Resistance wire is one of the relatively low-cost heating elements.
Easy to process and install: Resistance wires can be easily manufactured in different shapes, making them easy to install and replace.
Stable performance in high-temperature oxidation atmosphere: In high-temperature oxidation atmosphere, the resistance wire can maintain good performance and is not easily oxidized.
Disadvantages:

Limited applicable temperature range: The maximum operating temperature of the resistance wire is generally below 1200 ℃, suitable for situations where temperature requirements are not too high.
Relatively short service life: After long-term use at high temperatures, the service life of resistance wires may be relatively short and require regular inspection and replacement.
Elema
advantage:

Good high temperature resistance: Silicon carbon rods can work at higher temperatures, usually up to 1400 ℃ or above, with a higher temperature range than resistance wires.
Long service life: Under appropriate usage conditions, silicon carbide rods have a relatively long service life, reducing the frequency of replacement and maintenance costs.
Strong antioxidant properties: Silicon carbon rods will form a dense SiO ₂ protective film on their surface at high temperatures, allowing them to work for long periods of time in air and oxygen environments.
Disadvantages:

Sensitive to moisture: Silicon carbon rods are more sensitive to moisture, and prolonged exposure to humid environments may lead to performance degradation. Therefore, they need to be kept dry during storage.
High cost: The material and manufacturing cost of silicon carbide rods are relatively high, especially in large-scale applications, which may increase the overall cost of the equipment.
Silicon molybdenum rod
advantage:

Excellent high temperature resistance: Silicon molybdenum rods have excellent high temperature resistance and can be used for a long time in high temperature environments below 1700 ℃.
Strong oxidation resistance: The silicon dioxide protective layer generated on the surface of the silicon molybdenum rod can prevent further oxidation and is suitable for high temperature use in air.
Good conductivity: Silicon molybdenum rods have excellent conductivity, stable heating effect, and can provide a stable high-temperature environment for the sintering process.
Good resistance to various chemical media: Silicon molybdenum rods have good resistance to various chemical media and can adapt to complex experimental or production environments.
Disadvantages:

Brittle texture: The silicon molybdenum rod has a brittle texture and requires special care during installation and use to avoid collision and damage.
High cost: Silicon molybdenum rod is one of the more expensive heating elements.
summarize
When selecting heating elements for a vacuum tube furnace, it is necessary to comprehensively consider factors such as specific operating temperature, experimental or production requirements, and budget. Resistive wires are suitable for situations where temperature requirements are not too high, with low cost but relatively short service life; Silicon carbon rods have good high temperature resistance and long service life, but are sensitive to moisture and have a high cost; Silicon molybdenum rods have excellent high temperature resistance and conductivity, but their texture is brittle and expensive.