Binder burnout-material-process interaction during sintering of MnZn-ferrites

Abstract The binder burnout process step for MnZn-ferrite materials has been investigated in order to explain the origin of the binder burnout cracks that occur during the sintering of MnZn-ferrites. The binder burnout reaction extends to temperature regions where oxidation of the ferrite material (i.e. Mn 2+ ≧Mn 3+ ≧Mn 4+ ) occurs simultaneously. Under such conditions, the oxidation of the binder is favoured relative to that of the ferrite until the binder burn out oxidation has been completed. As a consequence, the ferrite oxidation occurs at higher temperatures and at higher reaction rates. The associated material shrinkage rates are therefore also increased, enhancing defect formation and eventual crack development within the products. When ferrite products of large dimensions are considered, the developed temperature gradients across the body provide a position dependency of these reactions, which results in the development of high stresses and ultimately in product cracking.