Silicon carbide has the characteristics of corrosion resistance, high temperature resistance, high strength, good thermal conductivity, and impact resistance. It is widely used in high temperature industries such as ceramics, refractories, and metallurgy. For the cement-bonded high-strength wear-resistant self-flowing castable commonly used in industrial furnaces and kilns in the above-mentioned industries, because most of the parts used are complex in structure and harsh environment, the material needs to have good strength, self-flowing and wear resistance. Therefore, when designing the formulation of high-strength wear-resistant self-flowing castables, in addition to controlling the structure of the aggregate material to ensure the strength and fluidity of the castable, the wear resistance and erosion resistance of the castable are improved by adding an appropriate amount of silicon carbide.
As the particle size of silicon carbide decreases, the rate of change of the castable line decreases, the wear resistance value increases, and the wear resistance decreases. The flexural and compressive strength first increase and then decrease. This is mainly due to the barren water of silicon carbide. It can enhance the density between particles, the smaller the particle size, the smaller the amount of water added to the castable, the denser the structure, and the larger silicon carbide is more wear-resistant than the fine powder; after 1100 ℃ heat treatment, the performance of silicon carbide is weak, and the change in particle size affects linear shrinkage Not obvious. As the silicon carbide particle size decreases, the flexural resistance and pressure resistance increase slowly, the wear resistance change trend does not change; after the temperature rises to 1400 ℃, the smaller the silicon carbide particle size, the more fully sintered the castable, and the denser the structure. The linear rate of change is reduced, and the structural strength is correspondingly increased. However, if the silicon carbide particle size is too small, the degree of oxidation is intensified, excessive liquid phase is generated, and the structural strength is reduced; at the same time, the high temperature liquid phase can promote the sintering of the sample and ease the silicon carbide The impact of particle size on the wear resistance of the material results in little change in the wear resistance value.
As the amount of silicon carbide added increases, the amount of water added to the castable increases and the workability becomes worse. After drying at 110°C, the silicon carbide did not undergo hydration reaction, the castable line shrinkage increased, and the early structural strength was poor and showed a tendency to rise first and then decrease. The wear resistance first increased and then decreased; at 1100°C, the castable was difficult to sinter , The degree of densification is not high, the binding force between particles is not large, the wear resistance is slightly reduced, and the strength change is not obvious; continue to heat up to 1400 ℃, with the increase of silicon carbide, the sample changes from shrinking to expansion and gradually increasing Part of SiC is oxidized to Al₂O₃ and fine Al₂O₃ reacts to form mullite phase. SiO₂ and mullite are deposited in the void and combine to make the material structure denser, the mechanical strength is significantly increased, and the wear resistance gradually increases. When the addition amount of silicon carbide is 20%, its flexural strength and compressive strength reach the highest value, but the addition amount of silicon carbide continues to increase, and more liquid phases are formed on the surface of the castable under high temperature, and the structural strength decreases. Considering the comprehensive performance and cost performance of the castable, it is determined that 20% of silicon carbide is the most appropriate.
