Silicon carbide heater (SIC)

Multiple models of SIC heaters manufactured according to customer requirements

Silicon carbide heater (SIC) 

The strength of silicon carbide is a non-metallic electric heating element, with high-purity hexagonal silicon carbide as the main raw material, processed and manufactured by siliconization and recrystallization and sintering at high temperature at 2200°C according to a certain proportion of material, the normal service temperature in the oxidizing atmosphere can reach 1450°C, and continuous use can reach 2000 hours. Compared with metal electric heating elements, this element has the characteristics of high usage temperature, oxidation resistance, corrosion resistance, long service life, microdeformation, and convenient installation and maintenance.

Properties of SIC heater 

Component texture: hard and brittle, resistant to cold and heat, not easy to deform at high temperature.

Density: 3.2 g/cm3

Mohs Hardness: 9.5

Specific heat: 0.17 kcal/kg•°C

Thermal conductivity: 20 kcal/m•h•degree

Coefficient of Linear Expansion: 5x10-6 (m/°C)

Silicon carbide heaters have good chemical stability and strong acid resistance. At high temperatures, alkaline substances have an erosive effect on it.

The silicon carbon rod element can interact with oxygen and water vapor for a long time above 1000°C: 1. Sic + 202 → Sio2 + CO2 2. Sic + 4H20 = Sio2 + 4H2 + CO2.

As a result, the SiO2 content in the component gradually increases and the strength slowly increases, resulting in aging. If there is too much water vapor, it will promote the oxidation of SiC, and the H2 produced by the formula 2 reaction will react with 02 in the air and H20 to produce a vicious cycle. Reduced component life. Hydrogen (H2) reduces the mechanical strength of the element. Nitrogen (N2) below 1200°C can prevent the oxidation of SiC above 1350°C and react with SiC, so that SiC can be decomposed, chlorine (CI2) can cause Sic to decompose completely. 

Product Application:

It is widely used in a variety of high-temperature electric furnaces and other electric heating equipment in the industries of magnetic materials, powder metallurgy, ceramics, glass, metallurgy, and machinery.

Production Process:

Our silicon carbide electric heating element has a new cold end production process, with excellent cold and hot end resistance ratio, energy saving, long service life, and avoids damage to the furnace body caused by excessive cold end temperature. The element begins to oxidize when used in air at 800°C, crystallizes cristobalite when the temperature reaches 1000-1300°C, and at 1500°C, the protective film reaches a certain thickness, so the oxidation rate of the element becomes extremely slow and tends to be stable. If the temperature continues to rise above 1627°C, the protective film is damaged and the oxidation rate increases significantly, causing premature damage to the element. Although the oxidation of the component is extremely slow during use, the resistance value will continue to increase after long-term operation, which is called aging. In order to slow down the aging rate, we use a unique technology to coat the surface of the heating part with a protective layer in the production process, which significantly improves the antioxidant performance of the component and prolongs the service life.

Service life

The service life of silicon carbide haters refers to the period from the time the silicon carbide rod is installed to the time the equipment is used until it can no longer function normally. However, according to the rules of the sic resistor industry, their service life refers to the time required for the resistance value of sic heaters to deteriorate (increase) to 4 times the initial value during use. Here we see that the lifespan of the silicon carbon strength does not have a clear time limit, but only a relative value, and now many manufacturers are not very clear about this concept, or do not pay attention, but only care about the time required for the silicon carbon strength to bend,  it breaks or doesn't get hot, which is obviously not scientific. To ensure the service life of silicon carbide heater, its quality must first be guaranteed. It should not bend or break before use, nor should it age to the point that it will no longer generate heat after a short period of use. This is due to poor quality. Second, it must be used in a scientific way. If the quality is the same and used scientifically, the service life of silicon carbide heater will be greatly extended.