Tube Furnace Widely used in ceramics, metallurgy, electronics, glass, chemical engineering, machinery, refractory materials, new materials development, specialty materials, and building materials, among other fields.

Working principle of the high-temperature tubular electric furnace: The thermocouple converts the furnace temperature into a voltage signal, which is then applied to the microcomputer-based temperature control regulator (as shown in Figure 1). The regulator compares this signal with the programmed setpoint and outputs an adjustable control signal. This adjustable signal is used to drive the trigger circuit, which in turn triggers the voltage regulator, thereby adjusting the furnace voltage and, consequently, the furnace temperature.

Selection of Heating Elements for Tubular Electric Furnaces
Silicon-molybdenum rods (distributed on the left and right sides of the furnace chamber).
Silicon-molybdenum rod electric heating elements are resistance heating components based on molybdenum silicide. When sintered molybdenum silicide products are heated to high temperatures in an oxidizing atmosphere, a dense quartz glass film forms on their surface, which effectively prevents further oxidation. Consequently, silicon-molybdenum rod elements exhibit exceptional high-temperature oxidation resistance. Their maximum service temperature in an oxidizing atmosphere is 1750°C. Moreover, the electrical resistance of these elements remains stable over time—increasing only with rising temperature—meaning they do not age; thus, new and aged elements can be used in combination. Like other ceramic materials, silicon-molybdenum rod elements are brittle at room temperature and prone to fracture; however, such failures can be avoided through proper use and installation.
Silicon carbide rods (distributed on the left, right, or around the furnace chamber)
Carbon rods are non-metallic high-temperature electric heating elements in rod form, manufactured primarily from high-quality, environmentally friendly silicon carbide material through a process involving preliminary shaping, high-temperature siliconization, and subsequent crystallization. Compared with metallic heating elements, carbon rods offer advantages such as higher operating temperatures, excellent oxidation and corrosion resistance, longer service life, minimal thermal deformation, and convenient installation and maintenance. Silicon carbide rods exhibit a relatively high resistivity; when heated in air, the surface temperature of the heating section can reach 1450°C. Their resistance–temperature characteristic curve is negative below 800°C and positive above 800°C. Furthermore, silicon carbide rods possess outstanding chemical stability, and acids have little effect on
It is essentially inert; however, alkali and alkaline earth metal oxides can corrode it under certain temperature conditions. At high temperatures, steam, hydrogen, halogens, sulfur, and other substances can also cause oxidation and corrosion. To ensure uniform furnace temperature and even load distribution on the heating elements, resistance matching must be performed prior to installation, maintaining resistance consistency within ±10%. During long-term operation of the electric furnace, if individual elements are damaged for various reasons and need to be replaced, the replacement elements should be selected based on the current increase in resistance, ensuring that their resistance values are appropriately matched; random selection of new elements for replacement is not permitted. If a large number of elements are damaged or the resistance has increased excessively to the point where the required furnace temperature can no longer be achieved, it is best to replace all elements with new ones. The removed elements should then be re-measured for resistance and used for resistance matching in the low-temperature zone.

Tube-type electric furnace http://www.ctjzh.com/