The production of Mn-Zn ferrite ceramics by injection moulding

A ceramic injection-moulding technique has been used for the preparation of bars and toroids of Mn-Zn ferrite. The binders were based on a combination of polypropylene, microcrystalline wax and stearic acid. Components up to 4 mm thick were fabricated; extended binder burn-out schedules, up to 8.5 days in duration, in a nitrogen atmosphere were required for the thicker parts. Sintered densities were typically 90% of the theoretical value. Initial permeabilities of the toroids were lower than expected (700–1600 rather than 4000) due to the smaller grain size (4–6 m) of the fired products. Optimization of the sintering schedule should enable the microstructure and magnetic properties to be improved.