Silicon carbon rod (SiC) is a high-performance electric heating element, and its main raw material is green high-purity hexagonal silicon carbide. After fine processing, high-temperature silicification and 2200℃ high-temperature recrystallization, a rod-shaped non-metallic high-temperature electric heating element is finally formed. The surface temperature of this element can be as high as 1450℃, but it should be noted that when the surface temperature exceeds 1500℃, its aging rate will be significantly accelerated, and it may even burn out. Under reasonable conditions of use, the continuous service life of silicon carbon rods can exceed 2000 hours. Its service life is not only affected by the intrinsic quality, but also related to multiple factors such as surface load, environmental atmosphere, heating method, and series and parallel connection of components.
In addition, silicon carbon rods have excellent physical and chemical properties. It is hard and brittle, has a small expansion coefficient, is resistant to rapid cooling and heating, is not easy to deform, and has good chemical stability. It can remain stable and non-reactive with strong acids. At the same time, the resistance value of silicon carbon rods changes with temperature, showing nonlinear characteristics. From room temperature to about 900℃, its resistance value gradually decreases; and after exceeding 900℃, the resistance value gradually increases. Especially at about 900℃, the resistance value of silicon carbon rods reaches the minimum.
When using silicon carbon rods, pay attention to the following points to ensure their performance and life:
1. The furnace temperature must not exceed the rated temperature for a long time to prevent damage to the heating element. At the same time, it is forbidden to inject flammable liquids or molten metals into the furnace.
2. Since silicon carbon rods are hard and brittle, special care should be taken during loading and unloading to avoid damage.
3. Silicon carbon rods should be stored in a dry environment to protect their aluminum-plated ends from moisture.
4. Molten KOH, NaOH, Na2CO3 and K2CO3 will decompose SiC at high temperatures, so ensure that these substances are isolated from silicon carbon rods. At the same time, silicon carbon rods should not come into contact with alkali, alkaline earth metals, sulfates, borides, etc. to avoid corrosion.
5. When wiring, ensure that the wiring of the silicon carbon rod is in close contact with the white aluminum head at the cold end of the rod to prevent sparking.
6. Silicon carbon rods react with chlorine (Cl2) at 600°C and react with water vapor at a high temperature of 1300-1400°C. It is worth noting that silicon carbon rods will not be oxidized in the temperature range below 1000°C, but when the temperature reaches 1350°C, its oxidation reaction will be significantly accelerated. In this temperature range, a layer of silicon dioxide (SiO2) protective film will form on the surface of the silicon carbon rod, which can prevent further oxidation of the silicon carbon rod.
7. As the silicon carbon rod is used for a longer time, its resistance value will gradually increase. This is because during use, the silicon carbon rod will undergo the following reactions: SiC reacts with oxygen (O2) to generate silicon dioxide (SiO2) and carbon dioxide (CO2), and SiC reacts with water vapor (H2O) to generate silicon dioxide (SiO2), hydrogen (H2) and carbon dioxide (CO2). Since the increase in silicon dioxide (SiO2) content will lead to an increase in the resistance value of the silicon carbon rod, new and old silicon carbon rods should not be mixed to avoid unbalanced resistance values, thereby ensuring the stability of the temperature field and extending the service life of the silicon carbon rod.
Post time: May-04-2025