Silicon Carbide RodsPrecautions:

① Operating Temperature  The higher the temperature of silicon carbide rods, the shorter their lifespan. Especially when the furnace temperature exceeds 1600°C, the oxidation rate accelerates, and the service life of silicon carbide rods decreases. Therefore, try to avoid excessively high surface temperatures of the rods, and it is necessary to minimize the temperature difference between the furnace and the rods.

②Surface Load  Surface load density refers to the rated power allowed per unit surface area of the heating section of the rod. Surface load density = rated power (W) / surface area of the heating section (cm2). Practical experience shows that a higher load density results in a greater temperature difference between the surface of the heating element and the furnace. A higher load density leads to a higher surface temperature of the rod, faster resistance increase, and a shorter lifespan of the SiC rod. Therefore, the surface temperature, load density, furnace atmosphere, and temperature are directly proportional to the aging rate of SiC rods and inversely proportional to their lifespan. The usage range curve in the diagram showing the relationship between furnace temperature and surface load density represents the critical line of surface load density. In practice, maintain a surface load of 1/2 to 1/3 of the critical line.

③ Furnace Atmosphere  During firing, silicon carbide rods may react with various chemical substances volatilized from the materials being fired. If they come into contact with gases such as water, hydrogen, nitrogen, sulfur, halogens, or molten aluminum, alkalis, salts, molten metals, or metal oxides, reactions, corrosion, or oxidation may occur.

④Kiln Operation Mode  Silicon carbide rods have a longer lifespan in continuous kilns compared to intermittent kilns. During use, the surface of silicon carbide rods oxidizes to form a silicon dioxide film. Prolonged use increases this film, leading to an increase in the resistance of the rods. The silicon dioxide film undergoes abnormal expansion and contraction near the crystallization critical point (1527°C). In intermittent kilns, where the temperature fluctuates around this point during cyclic use, the silicon dioxide film is repeatedly damaged, accelerating oxidation.