Mechanical properties of porcelain insulator enhanced with spherical mullite powders
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To enhance the mechanical properties of high-voltage porcelain insulator, the columnar mullite agglomerated sphericalpowder was introduced as a reinforcing phase. High-alumina based porcelain insulator containing varying spherical mullitepowder contents (0–30 wt.%) were fabricated by cold isostatic pressing. The effects of reinforcing phase content on physicaland mechanical properties, phase composite and microstructure were investigated, and the underlying strengthening andtoughening mechanisms were elucidated. The results show that the 12 wt.% spherical mullite powders (S12) added sampleexhibited optimal overall properties. The compressive strength and flexural strength of S12 reached 321 MPa and 107MPa, respectively, showing an obvious improvement over the reference sample S0. Especially, the fracture toughness ofS12 increased by 45.4% to 5.1 MPa·m1/2 and the critical crack size improved by 60.1% to 714 μm compared with S0. Microstructural analysis revealed that the original columnar mullite in spherical particles interlaced with in-situ generatedmullite forming a three-dimensional interlocking network. The formed unique microstructure effectively absorbed elasticstrain energy and suppressed crack propagation, achieving strengthening and toughening of the porcelain insulators.
Abstract
To enhance the mechanical properties of high-voltage porcelain insulator, the columnar mullite agglomerated sphericalpowder was introduced as a reinforcing phase. High-alumina based porcelain insulator containing varying spherical mullitepowder contents (0–30 wt.%) were fabricated by cold isostatic pressing. The effects of reinforcing phase content on physicaland mechanical properties, phase composite and microstructure were investigated, and the underlying strengthening andtoughening mechanisms were elucidated. The results show that the 12 wt.% spherical mullite powders (S12) added sampleexhibited optimal overall properties. The compressive strength and flexural strength of S12 reached 321 MPa and 107MPa, respectively, showing an obvious improvement over the reference sample S0. Especially, the fracture toughness ofS12 increased by 45.4% to 5.1 MPa·m1/2 and the critical crack size improved by 60.1% to 714 μm compared with S0. Microstructural analysis revealed that the original columnar mullite in spherical particles interlaced with in-situ generatedmullite forming a three-dimensional interlocking network. The formed unique microstructure effectively absorbed elasticstrain energy and suppressed crack propagation, achieving strengthening and toughening of the porcelain insulators.