Effect of modified tabular alumina aggregates on mechanical properties and microstructure of Al2O3–Al–C material

Abstract

Al2O3–Al–C material was prepared by tabular alumina aggregates (1–3 mm, 0–1 mm, 0.045 mm), modified tabular alumina aggregates (0.5–3 mm), ultra fine α-Al2O3 powder, aluminum powder, flaky graphite as the raw materials, and thermosetting phenolic resin as binder. The coating strength of the modified tabular alumina aggregates was tested, and the physical properties of the specimens at room and high temperature were examined. The phase composition and microstructure of the specimens were analyzed by XRD and SEM. The results showed that: (1) After mixing and wear experiment, the dropping ratio of the coated Al particles was 2.58%, and the coating strength was fairly good; (2) The coated Al particles reacted with C and N2in situ generated acicular and fibrous Al4C3 and AlN, enhancing the bonding strength between the aggregates and matrix, improving the hot modulus of rupture (HMOR) of the material. In addition, Al4C3 and AlN have a lower coefficient of thermal expansion and higher thermal conductivity, which can absorb the thermal expansion of the particles, alleviate the thermal stress inside the material, and improve the thermal shock resistance of the material.