Reaction-bonded silicon carbide square beams are suitable for the load-bearing structural frames of tunnel kilns, shuttle kilns, double-layer roller hearth kilns, and other industrial kilns. This product offers high load-bearing capacity at elevated temperatures, does not bend or deform during long-term use, and has a service life several times longer than that of materials made from other substances. It is an ideal kiln furniture for industries such as sanitary ceramics and electrical porcelain. The product exhibits excellent high-temperature flexural strength, thermal shock resistance, and oxidation resistance. It remains deformation-free over prolonged use, significantly reduces energy consumption, and does not increase the weight of the kiln car.