Glass Furnace White Coating Corrosion-Resistant Silicon Carbide Rods

Silicon carbide rods come in various shapes such as equal-diameter type, U-type, right-angle type, large-head type, gate-type, H-type, h-type, threaded type, five-section type, groove type, etc. They are widely used in various high-temperature electric furnaces, including casting furnaces, tempering furnaces, lifting furnaces, vacuum furnaces, atmosphere furnaces, muffle furnaces, laboratory furnaces, smelting furnaces, porcelain furnaces, tube furnaces, as well as large industrial electric furnaces like car-bottom furnaces, mesh belt sintering furnaces, and tunnel kilns. These rods are made from high-purity silicon carbide as the main raw material, with the addition of industrial silicon, carbon powder, and other materials. They are manufactured through multiple processes including molding, drying, high-temperature sintering, cutting, welding, aluminum plating, resistance testing, and multiple inspections, resulting in a non-metallic rod-shaped or tubular high-temperature electric heating element. They exhibit good acid resistance but poor alkali resistance. At room temperature, they are hard and brittle, resistant to rapid cooling and heating, not easily deformed at high temperatures, with high operating temperatures, good oxidation resistance, fast thermal conductivity, strong thermal radiation capability, low thermal expansion coefficient, and high thermal efficiency. They are easy to use, can be connected in parallel, series, or mixed configurations, and can be installed horizontally or vertically, making them a common heating element in medium to high-temperature electric furnaces.

When the temperature in an electric furnace or kiln reaches 800 degrees Celsius, silicon carbide rods begin to oxidize. At temperatures between 1000 and 1300 degrees Celsius, a layer of silicon dioxide protective film forms on the surface of the heating element. Above 1300 degrees Celsius, cristobalite crystals (also known as silicon dioxide, white silica, or white carbon black) are produced. As the temperature continues to rise, the cristobalite layer reaches a certain thickness, which significantly slows down the oxidation rate of the element, making it more stable. However, when the temperature exceeds 1500 degrees Celsius, the protective film is damaged, and the oxidation rate increases noticeably, leading to premature aging of the element. This is why the operating temperature of silicon carbide rods should not exceed 1500 degrees Celsius. The ideal operating temperature range for silicon carbide elements is between 1000 and 1350 degrees Celsius. To extend their service life and maximize their value, it is advisable to avoid exceeding this range and use them rationally.
It is recommended to use the elements continuously whenever possible, as intermittent use in kilns can significantly reduce their lifespan. For wiring, parallel connection is advised, and the resistance between elements should be maintained at around ±0.1 ohms.
Prolonged operation of the elements leads to an increase in resistance. Nowadays, manufacturers add a protective layer to the surface of the heating element, which significantly improves its oxidation resistance and extends its service life. At 1300 degrees Celsius, the element is prone to react with alkalis or alkaline oxides, forming silicates, which can noticeably affect the element's temperature and should be avoided as much as possible.
Dengfeng Minghui High-Temperature Elements Co., Ltd. specializes in custom-made coated silicon carbide heating elements. The company strictly tests raw material quality, including purity, particle size, and impurities, ensuring that each batch meets production technical requirements. During production, attention is paid to detail control, such as ingredient ratios, pressure, density, sintering temperature, and resistance. With ample semi-finished product inventory, fast delivery for custom orders, excellent service, and extensive experience, we welcome your inquiries.