To enhance the mechanical properties of high-voltage porcelain insulator, the columnar mullite agglomerated spherical powder was introduced as a reinforcing phase. High-alumina based porcelain insulator containing varying spherical mullite powder contents (0–30 wt.%) were fabricated by cold isostatic pressing. The effects of reinforcing phase content on physical and mechanical properties, phase composite and microstructure were investigated, and the underlying strengthening and toughening mechanisms were elucidated. The results show that the 12 wt.% spherical mullite powders (S12) added sample exhibited optimal overall properties. The compressive strength and flexural strength of S12 reached 321 MPa and 107 MPa, respectively, showing an obvious improvement over the reference sample S0. Especially, the fracture toughness of S12 increased by 45.4% to 5.1 MPa·m^1/2 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 generated mullite forming a three-dimensional interlocking network. The formed unique microstructure effectively absorbed elastic strain energy and suppressed crack propagation, achieving strengthening and toughening of the porcelain insulators.

Keywords: Porcelain insulators, Spherical mullite powders, Enhancing and toughening.

The authors acknowledge Ms. Yunqin Gao and Ms. Xing Hou, High-Temperature Ceramics Institute of Xi'an University of Architecture and Technology, for their assistance with the preparation and performance test of refractories.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

This work was supported by the Funding of 2024 Science and Technology Plan Project of Inner Mongolia Power Company (No. 2024-4-30, No. 2024-4-32).

Yonggang Yue: Conceptualization, Methodology, Supervision, Writing, Funding Acquisition; Xiaoyun Tian: Data Curation, Formal Analysis, Writing; Xiaochuan Chong: Experimental Work, Software, Writing, Original Draft Preparation; Donghai Ding: Resources, Review & Editing; Guoqing Xiao: Investigation, Validation, Writing, Review & Editing; Liming Wang: Project Administration, Data Interpretation, Writing; Bin Cao: Methodology, Project Administration, Writing; Lanjun Yang: Formal Analysis, Data Curation, Writing.

The data that support the findings of this study are available from the corresponding author upon reasonable request.