Silicon carbide refractory material boasts high hot strength, excellent creep resistance, and thermal conductivity properties that make it popularly used in aluminum markets for casting bricks for sidewalls of aluminum reduction cells.
Oxidation of refractory ceramics at temperatures above 1000 degC is extremely detrimental, as this leads to the formation of cristobalite which affects performance of kiln furniture and further limits its performance.
High Temperature Strength
Silicon carbide is an exceptional refractory ceramic material, offering superior thermal shock resistance and outstanding mechanical strength across a range of temperatures. These features make Silicon Carbide particularly well suited for applications requiring high temperature performance such as in metallurgy, kiln furniture manufacturing and waste-to-energy industries.
Silicon carbide stands out due to its unique chemical makeup as an extremely stable material for use across a range of temperatures and environments, while remaining water and alcohol insoluble – making it highly desirable in harsh environments where aggressive chemicals or conditions could erode other materials more quickly.
Kerui’s silicon carbide refractory castables offer a cost-effective and long-term solution to furnaces that experience intense heat stress, spalling and corrosion. Their low cement content reduces permeability to increase efficiency while eliminating the need for additional refractory materials, thus improving furnace performance and service life.
CUMIFRAC Refractory Bricks are manufactured using a mixture of alumina and silicon carbide raw materials synthesised in a resistance-type electric furnace at temperatures exceeding 2500degC, to produce bricks with higher strength compared to conventional fireclay refractories, are chemically inert, can resist slag attack and flame erosion as well as having 10x greater thermal conductivity than its fireclay counterpart and can even be formed into complex shapes by our state-of-the-art manufacturing facilities.
Corrosion Resistance
Silicon carbide has proven its superior resistance to corrosion across various environments, making it an excellent material choice for applications requiring exposure to chemical environments. Furthermore, silicon carbide’s durability and wear resistance make it suitable for abrasive products, and its strength has lead to its use in other refractory and ceramic applications.
Corrosion resistance can be improved by strengthening oxynitride and nitride bonds in silicon carbide, leading to enhanced passivation of its surface as well as reduced rates of oxidation when exposed to aqueous chemicals.
Enhancement technology has been successfully applied to refractory bricks used as aluminum reduction cell sidewall linings, with impressive results for their oxidation resistance and cryolite corrosion tests. They also scored well during various forms of testing for both oxidation and corrosion.
Silicon carbide stands up well against abrasive and chemical wear. In addition, its thermal shock resistance makes it an excellent choice for environments characterized by extreme temperatures and stress levels. Furthermore, its higher thermal conductivity makes it useful in many refractory applications – it is especially well suited for furnace linings and kiln components; burner nozzles; jet and flame tubes; thermocouple protection tubes are some of the many uses refractories have today; it is used extensively in metal refining applications including vertical tank distillation furnaces, zinc powder furnace liners; aluminum electrolytic cells; copper melting furnace linings among many others.
Thermal Conductivity
Silicon carbide refractory’s thermal conductivity allows it to operate at high temperatures while still remaining strong, as well as resist chemical attack and maintain its chemical purity at higher temperatures, making it a top choice for wafer tray supports and paddles in semiconductor furnaces, with its low thermal expansion making it suitable for substrates, inner walls of fusion reactors and solar concentrators.
Silicon carbide refractories perform well in many environments; however, one drawback in process industry applications lies with their oxidation resistance at temperatures above 900oC. Oxidation occurs when exposed to oxygen combined with heat; this leads to the formation of cristobalite; an irreparably damaging form of silicon dioxide that can compromise shapes and cause internal stress that leads to eventual failure.
Saint-Gobain Ceramic Materials research and development teams created enhanced nitride-bonded silicon carbide and oxynitride-bonded silicon carbide compositions that deliver significantly improved oxidation resistance compared to standard bricks used as kiln furniture in blast furnaces and aluminum electrolysis cells. These enhanced silicon carbide refractory formulations also help extend the lifespan of hearth plates, recuperator tubes and pusher slabs while decreasing energy costs and firing costs significantly.
Thermal Shock Resistance
Silicon carbide is an impressive structural material due to its exceptional high temperature strength, corrosion resistance and thermal conductivity properties. Unfortunately, these depend heavily on the chemical and physical environment in which a brick is being used; one major drawback being its vulnerability to oxidation, leading to volumetric expansion leading to stress-induced damage in refractories.
Oxidation can significantly weaken SiC’s structural integrity. Thus, new silicon carbide refractory compositions that can prevent the formation of cristobalite and other crystalline phases at high temperatures are required. Saint-Gobain Ceramic Materials has developed CUMIFRAC products for use in metallurgy, kiln furniture manufacturing and waste-to-energy sectors that offer increased oxidation protection.
Development of these new refractory compositions involved extensive laboratory testing of both raw fire clay and castables as well as exposure to different furnace conditions to evaluate their ability to resist oxidation. Refractory castables were specifically engineered to contain various volume fractions of SiC particles and Zirconia (ZrO2) bubbles. Mechanical properties of these materials were evaluated both before and after being subject to a custom-designed thermal shock cycle, using elastic modulus and crushing strength measurements as parameters of comparison with thermal shock indices predictions. The most promising compositions were then manufactured as bricks for use in aluminum reduction cell sidewalls.
English 
Swedish