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研究生:沈國宏
研究生(外文):Shen, Kwo-Hung
論文名稱:鎳鋅銅鐵氧磁體晶粒控制之研究
論文名稱(外文):The Study of Grain Size Control of Ni-Zn-Mn Ferrite
指導教授:魏萬益
指導教授(外文):Wan-Yi Wei
學位類別:碩士
校院名稱:大同工學院
系所名稱:材料工程學系
學門:工程學門
學類:材料工程學類
論文種類:學術論文
論文出版年:1997
畢業學年度:85
語文別:中文
論文頁數:75
中文關鍵詞:鐵氧磁體微觀組織磁特性穿晶沿晶破裂
外文關鍵詞:ferrite systemmicrostructuremagnetic propertiestransgranularintergranular
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摘要本研究以Ni0.28Zn0.54Cu0.18Fe2O4為主成分,分別加入ZrO2、Ta2O5
、Bi2O3等添加劑,以瞭解ZrO2、Ta2O5、Bi2O3等對微觀組織的影響,並
進而瞭解微觀組織與磁特性間之關係。由實驗發現duplex成長對組成敏感
,可藉由添加劑來影響,且隨著燒結溫度下降或添加劑的量增加,破斷面
有由穿晶轉為沿晶破裂的趨勢,這乃因組織均勻性變差,使得晶界與晶粒
的強度不同而造成。研究中亦發現,磁性相的組成對燒結溫度極為敏感,
以本系統而言,有最佳之磁性燒結溫度約在1025℃∼1050℃之間。另外,
液相燒結固然可以使晶粒間的物質傳輸容易,使化學均勻性較好,但也帶
來提高了晶粒成長的驅動力,所以對於鐵氧磁體而言,要利用液相作低溫
燒結來控制晶粒大小,許多動力學的因素必須考慮,方能得到良好的燒結
效果。從功率損失的觀點來看,本系統中Hysteresis loss佔極重要的份
量,可知Domain wall的移動,所必須克服的異方向能量是造成Total
power loss貢獻的主因。而1025℃燒結時有最低的k值,所以Hysteresis
loss小,同時其μi亦高。因此對本系統來講,Power loss的改善應以改
善磁特性之方向為主要手段。
Abstract In this study, the ferrite system, Ni0.28Zn0.54Cu0.18
Fe2O3, was prepared under different sintering temperature and
adding different additives, ZrO2, Ta2O5, and Bi2O3. The purpose
of this study is to investigate the effect of additives on the
microstructure of Ni-Zn-Cu ferrite, and try to find the
relationship between microstructure and magnetic properties.
From the optical observation, the growth of duplex is sensitive
to the chemical compositions and could be effected by additive
concentrations. The SEM photographs of fractured surface show
that as the sintering temperature decreasing or additives amount
increasing the fracture mode changes from transgranular to
intergranular. This is due to the degrade of microstructure
uniformity and different strength of grain and grain boundary.
At the same time, we also find that the composition of magnetic
phase is very sensitive to sintering temperature. In this
system, the best magnetic sintering temperature is between
1025℃and 1050℃. Although liquid phase sintering is one of the
densification mechanism of powder compaction. This process could
enhance mass transportation between grain and grain, which
results to chemical homogeneity of grains. However, it is also
promotes grain growth. Since grain size of ferrite is lose-
related to magnetic properties, application of liquid phase
sintering to ferrite system, special attention has to be paid.
From the results of power loss measurement, we found the
hysteresis loss is dominate. This result is consistent with m-T
property. Another importance is that the hysteresis loss bear
the most of total power loss, it means that the energy of moving
domain wall (Magnetocrystalline anisotropy energy) is the major
contribution of total power loss, and as sintered at 1025℃,
there is the minimum anisotropy constant k, due to low
hysteresis loss. As a result that to decrease power loss the
enhancement of magnetic properties is very important for this
system.
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