Effect of organic solvent on the cold sintering processing of SrFe12O19 platelet-based permanent magnets

TL;DR

This study explores how different organic solvents influence the cold sintering process of SrFe12O19 platelet-based permanent magnets, affecting their structural, morphological, and magnetic properties, with post-thermal treatment improving mechanical integrity.

Contribution

It introduces the use of various organic solvents in cold sintering of SrFe12O19 magnets and analyzes their effects on properties and magnetic response, optimizing processing conditions.

Findings

Organic solvents modify morphological and structural properties.

Post-annealing enhances mechanical integrity and density.

Glacial acetic acid yields the highest coercivity.

Abstract

In this work we have investigated the effect of the solvent during the processing of SrFe12O19 platelet-based permanent magnets by cold sintering process (CSP) plus a post-thermal treatment. Several organic solvents: glacial acetic acid, oleic acid and oleylamine have been analyzed, optimizing the CSP temperatures at 190-270 {\deg}C, under pressures of 375-670 MPa and 6-50 wt% of solvent. Modifications in the morphological and structural properties are identified depending on the solvent, which impacts on the magnetic response. Independently of the solvent, the mechanical integrity of ferrite magnets obtained by CSP is improved by a post-annealing at 1100 {\deg}C for 2 h, resulting in relative densities around 92 % with an average grain size of 1 {\mu}m and a fraction of SrFe12O19 phase > 91 %. Hc > 2.1 kOe and MS of 73 emu/g are obtained in the final sintered ceramic magnets, exhibiting the highest HC value of 2.8 kOe for the magnet sintered using glacial acetic acid.