Dependence of Compaction Behavior of Spray-Dried Ferrite Powders on the Kinds and Concentrations of Binder Systems

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J. Korean Ceram. Soc. > Volume 32(9); 1995 > Article

Journal of the Korean Ceramic Society 1995;32(9): 1047.

결합제의 종류와 양에 따라 분무건조된 페라이트 분말의 성형특성

홍대영, 변순천, 제해준¹, 홍국선

서울대학교 무기재료공학과
¹한국과학기술연구원 세라믹스연구부

Dependence of Compaction Behavior of Spray-Dried Ferrite Powders on the Kinds and Concentrations of Binder Systems

ABSTRACT

Mn-Zn ferrite granules were formed by a spray-drying method of the slurry containing different kinds and concentrations of binders at various temperatures. The slurry was made by conventional ceramic processing method, that is, by mixing Fe2O3, MnO, ZnO powders (52 : 24 : 24 mol%), calcining and milling. Typical shape of the spray dried granules was spherical. The compaction behavior of these granules was dependent on the spray-drying temperature and the kind and concentration of binders. At lower pressure the granules were displaced and at higher pressure the granules were deformed and fractured to fill pores among the granules. The optimum concentration of the binder was 0.5wt%. The granules containing 0.5wt% PVA 205 were deformed and fractured well and the green density was higher than others. At higher concentrations of the binder the granules were deformed rather than fractured, therefore the green density was lowered because of the remaining unfilled pores. The decomposition temperature and the heat released were increased with increasing the concentration of the binders. The compaction response of the granules containing PVA 205 was more efficient than those containing PVA 217 and PVA 117. Green density was not dependent on the degree of hydrolysis of the binders. The compaction response of the granules spray-dried at 15$0^{circ}C$ was most efficient.

Key words: Spray drying, Ferrite, Compaction, Binder