Process Optimization of In Situ Magnetic-Anisotropy Spark Plasma Sintering of M-Type-Based Barium Hexaferrite...

This paper introduces a new spark plasma sintering technique that is able to order crystalline anisotropy by in-series/in situ DC electric coupled magnetic field. The process control parameters have been investigated on the production of anisotropic BaFe₁₂O₁₉ magnets based on resulted remanence (Mr). Sintering holding time (H.T.), cooling rate (C.R.), pressure (P), and sintering temperature (S.T.) are optimized by Taguchi with L9 orthogonal array (OA). The remanent magnetization of nanocrystalline BaFe₁₂O₁₉ in parallel (Mr^ǁ) and perpendicular (Mr^Ʇ) to the applied magnetic field was regarded as a measure of performance. The Taguchi study calculated optimum process parameters, which significantly improved the sintering process based on the confirmation tests of BaFe₁₂O₁₉ anisotropy. The magnetic properties in terms of Mr^ǁ and Mr^Ʇ were greatly affected by sintering temperature and pressure according to ANOVA results. In addition, regression models were developed for predicting the Mr^ǁ as well as Mr^Ʇ respectively.