Hydrothermal Deposition of ZnO Layer on Fe-Based Amorphous Fibres Used for the Preparation of Cold Sintered Fibre-Based Soft Magnetic Composites

Abstract

This paper presents findings on the influence of hydrothermal deposition processing parameters (precursor concentration and deposition duration) on the characteristics of ZnO layers deposited on the surface of amorphous Fe-based fibres. The characteristics of the coated fibres, especially the deposited layer, were investigated from structural, morphological, chemical, thermal and magnetic points of view. It was found that the use of a zinc acetate-based solution of 0.05 M concentration and a deposition duration of 24 h leads to a continuous, thin and adherent layer of ZnO on the surface of the fibres. The thickness of the ZnO layer is 450–500 nm, as shown by TEM-EDX investigations. The ZnO coated fibres were used to prepare fibre-based soft magnetic composites via a cold sintering process. The composites obtained are the first reported soft magnetic composites based on amorphous fibres. The coercive field of the cold sintered composites is 3.5 to 8.6 times lower, and the maximum relative permeability is 2.4 times larger, than the best coercive field and the maximum relative permeability reported until now for a crystalline fibre-based soft magnetic composite. The initial relative permeability of cold sintered composites is constant up to the frequency of 1000 Hz.