Thermal spraying of Co,Ti-substituted Ba-hexaferrite coatings for electromagnetic wave absorption applications

Co,Ti-substituted Ba-hexaferrite (BaCoTiFe10O19) coatings for applications as microwave absorbers were deposited by the APS and HVOF techniques, using BaCoTiFe10O19 powders manufactured by solid-state reaction followed by spray-drying. The SEM + EDX, XRD and micro-Raman analyses indicated that impact quenching of molten agglomerates on the substrate hindered the crystallisation of the hexaferrite structure, resulting in poor magnetic properties of the coatings. Adjusted processing conditions enabled the deposition of a coating retaining enough hexaferrite phase, whose magnetic properties, close to bulk BaCoTiFe10O19, are very promising for electromagnetic wave absorption.