铁氧体颗粒聚集状态及烧结工艺对晶粒生长与微结构的影响

The Influence of Ferrite Particle Agglomerating State and Sintering Processing on the Microstructure and Grain Growth

研究了ＮｉＣｕＺｎ 铁氧体颗粒聚集状态以及烧结工艺对晶粒生长与微结构的影响。指出，松散粉料烧结后，其平均晶粒尺寸要比经成型烧结后的磁环表面的颗粒尺寸小得多，而磁环表面平均晶粒尺寸却又大大小于内部晶粒尺寸。用化学方法制得的低温烧结ＮｉＣｕＺｎ 铁氧体具有很高的烧结活性，在８８０℃左右烧结即可获得较高的烧结密度以及细而均匀的微结构。但当烧结温度超过１０００℃时，由于低熔点的ＣｕＯ 导致液相烧结，从而会导致晶粒狂长。烧结过程中，升温速率过快，会导致大量气孔来不及消除，而残留于晶粒内部，使烧结体的密度降低。当烧结温度过高（１１００℃左右），在晶界将会有“孤岛”状的析出物，电子探针表明该析出物为ＣｕＯ。

The influence of ferrite particle agglomerating state and sintering processing on the microstructure and grain growth was studied in this paper.It was shown that,after the sintering of loosely agglomerated powder,the average grain size is smaller than that of the surface of sintered ferrite toroid,while the average grain size of the toroidal surface is much smaller than that of internal of the toroid.As the low temperature sintered NiCuZn ferrite made by chemical method has quite good sintering activity,higher density and uniform microstructure were obtained at a sintering temperature of about 880℃.But,when the sintering temperature is above 1000℃,the liquid phase sintering resulted from CuO with low melting point will cause ferrite grain to grow rapidly.The island shaped CuO which precipitated at the grain boundary of the ferrite body sintered at 1100℃ was observed by SEM and EDAX techniques.