Fracture behavior of lightweight mullite-SiC refractories with porous aggregates coated with glass ceramic

Owing to the periodic mechanical stresses frequently suffered by refractories applied in cement rotary kilns, the study of fracture behavior is particularly significant for long life, safety, and reliable operation. In this work, bauxite aggregates and lightweight mullite aggregates with and without glass ceramic coatings were utilized in mullite-SiC refractories, and the fracture properties of the refractories were investigated and compared using the Brazilian test, digital image correlation technology, crack propagation path analysis, etc. The results show that the application of a glass ceramic coating on the surface of lightweight aggregates strengthens the interface between the porous mullite aggregates and the matrix, not only improving the compressive and tensile strength of the material but also increasing the number of crack branches and further improving fracture toughness. The compressive strength, tensile strength, and tensile displacement of refractories with 50 vol% coated lightweight aggregate increased by 53.1%, 67.6%, and 42.3%, respectively, compared to traditional mullite-SiC refractories.