Effect of sintering temperature and time on surface hardness of cold-pressed SrFe₁₂O₁₉ pellets: An orthogonal experimental approach

Abstract

This study explores the influence of sintering temperature and time on the surface hardness and microstructure of cold-pressed SrFe₁₂O₁₉ permanent magnet compacts. A two-factor orthogonal experimental design was employed to construct a regression model with high predictive accuracy (R² = 97.23%, AICc = 55.14). Rietveld refinement of X-ray diffraction (XRD) data confirmed the formation of a single-phase of M-type hexagonal structure, with crystallite sizes ranging from 39.5 to 61.8 nm and microstrain values dependent on sintering conditions. The optimal hardness of 93.63 HV was obtained at 1000 °C for 120 minutes, closely matching the model prediction (95.287 HV) with a deviation of only 1.74%. The results demonstrate that controlling sintering parameters is crucial for minimizing microstrain and maximizing hardness, offering practical insights for the processing of high-performance ferrite-based magnetic ceramics.