Relative temperature coefficient of initial permeability 初始磁導(dǎo)率比溫度系數(shù)
Alternating - current initial permeability 交流初透磁率
The raw materials , the composition , the time of milling , the calcining temperature , the different additives , the sintering temperature and the sintering parameters were investigated . the result showed : it was advantaged to obtain high initial permeability mnzn ferrite with stable frequency characteristic using high - purity raw materials ; in order to obtain mnzn ferrite with high properties , we must control strictly the composition ; it could improve the properties of mnzn ferrite by optimizing calcining temperature . the lower calcining temperature made the permeability higher , and the higher calcining temperature could promote the frequency characteristic of permeability ; we chosen the right time of milling according to the requirement of power diameter ; in order to improve the properties of mnzn ferrite , it is necessary to add effective additives . in this dissertation , the influence of bi2o3 、 moo3 、 k2co3 、 co2o3 were investigated ; the sintering temperature , the time of heat - retaining and sintering parameters were the key factors of preparing high permeability mnzn ferrites 研究結(jié)果表明:采用高純度的fe2o3有利于獲得高起始磁導(dǎo)率且頻率特性優(yōu)良的鐵氧體;為了制備所需性能的鐵氧體,需要嚴(yán)格控制配方中各種原材料的含量,優(yōu)化配方;由于粉體活性受預(yù)燒條件的影響,所以對不同要求的鐵氧體選擇的預(yù)燒條件就不一樣,適當(dāng)降低預(yù)燒溫度有利于獲得較高的起始磁導(dǎo)率,而為了獲得良好的頻率特性可以適當(dāng)?shù)靥岣哳A(yù)燒溫度;根據(jù)對粉體顆粒粒徑的不同需求,可以選擇不同的球磨時間;而有效的添加劑是改善材料性能的必要條件,本文在添加劑的研究中主要對bi2o3 、 moo3 、 k2co3 、 co2o3的影響分別作了詳細(xì)地討論;燒結(jié)溫度、保溫時間和燒結(jié)氣氛是高磁導(dǎo)率mnzn鐵氧體制備最關(guān)鍵的工藝,適宜的燒結(jié)工藝可以獲得理想微結(jié)構(gòu)和組成,從而得到高性能的鐵氧體材料;而從材料的微結(jié)構(gòu)上來看,要提高材料的截止頻率,就要適當(dāng)?shù)丶?xì)化晶粒、增加晶粒內(nèi)部的氣孔。
We emphatically discussed how the sintering environment affected initial permeability ( ui ) , and how different contents of zno varied saturation magnetization ( bs ) and curie temperature ( tc ) . the factors of affecting temperature stability of ferrites were analyzed . finally , we compared sol - gel auto - combustion way with conventional ceramic method 其中重點探究了燒結(jié)條件對鐵氧體起始磁導(dǎo)率_ i的影響以及不同原料配方對鐵氧體飽和磁感應(yīng)強度bs和居里溫度tc的影響,而且探討了溫度穩(wěn)定性的產(chǎn)生機理及摻雜co ~ ( 2 + )對鐵氧體溫度穩(wěn)定性的影響。
Thinning the crystal grain and increasing the center vent are effective approach to raise the limiting frequency of high permeability mnzn ferrite . through large quantities of experiments , we made progress in raising limiting frequency of high permeability mnzn ferrite . we prepared the broad band mnzn ferrite of which the initial permeability was 10000 通過采用上述實驗中的優(yōu)化配方、添加劑組合以及制備工藝,我們在高磁導(dǎo)率材料的寬頻特性方面取得了很大的進(jìn)展,研制出了起始磁導(dǎo)率磁導(dǎo)率為10000的寬頻mnzn鐵氧體材料,當(dāng)頻率達(dá)到300khz時,起始磁導(dǎo)率下降不到20 % ,其性能相當(dāng)于epcos公司改進(jìn)的t38材料。