关键词: 高压电瓷, 片状Al₂O₃, 粒径, 断裂韧性

Abstract: To improve the brittleness and enhance the mechanical properties of electrical porcelain materials,high-alumina porcelain insulators were prepared using spray-granulated powder for porcelain insulators as the raw material,introducing flake alumina (ρ-Al₂O₃) as a two-dimensional reinforcing phase,and pressureless sintering at 1 300 ℃ for 2 h.The effects of the particle size distribution of ρ-Al₂O₃ treated through different dispersion methods (mechanical grinding,vibratory milling,and dry ball milling),on the mechanical properties,phase composition,and microstructure of the insulators were investigated,and the toughening mechanism was analyzed.The results indicate that dry ball milling can most effectively refines ρ-Al₂O₃,reducing its d₅₀ to 3.73 μm while significantly promoting mullite formation and microstructural optimization during sintering.Compared to the sample containing mechanically-ground or vibratorily-milled ρ-Al₂O₃,the one with dry ball-milled ρ-Al₂O₃ exhibits the best overall performance,showing the lowest apparent porosity,flexural strength of 119 MPa,elastic modulus of 172 GPa,Vickers hardness of 30 GPa,and fracture toughness of 7.51 MPa·m^1/2.The fracture toughness significantly increases by 73.8% compared to the sample without ρ-Al₂O₃.This improvement primarily stems from the three-dimensional interlocking network structure constructed by the refined ρ-Al₂O₃ and in situ formed mullite whiskers,which effectively inhibits crack propagation through multiple toughening mechanisms,including crack deflection,branching,and bridging,thereby achieving the strengthening and toughening of high-alumina porcelain insulators.

Key words: high-voltage electrical porcelain, flake alumina, particle size, fracture toughness