生产各向异性轧制磁体用铁氧体磁粉,通常采用的氧化铁Fe_2O_3与氧化锶SrO的摩尔比低于铁氧体摩尔比理论值6.0。由于碱性环境下容易生成Cr^(6+),需通过回火后湿式表面处理工序去除Cr^(6+)。通过调整预烧工艺参数,考察摩尔比在5.65~6.5时...生产各向异性轧制磁体用铁氧体磁粉,通常采用的氧化铁Fe_2O_3与氧化锶SrO的摩尔比低于铁氧体摩尔比理论值6.0。由于碱性环境下容易生成Cr^(6+),需通过回火后湿式表面处理工序去除Cr^(6+)。通过调整预烧工艺参数,考察摩尔比在5.65~6.5时磁粉中的Cr^(6+)含量,并探究省去表面处理工序的可能性。研究发现摩尔比大于6.2时,Cr^(6+)含量<10 ppm。摩尔比在5.9~6.3时,磁粉剩磁>257 m T,内禀矫顽力=270 k A/m。通过调整预烧和添加剂比例,在摩尔比为6.2、添加剂含量3%、1100℃预烧条件下获得磁体剩磁达264 m T的性能。通过对预烧温度对比,在1040~1120℃随预烧温度提高,剩磁逐渐提高,之后继续提高,剩磁逐渐降低。展开更多
经湿磨及干燥工序后,铁氧体磁粉颗粒被解碎成单畴颗粒,由于液桥力的作用,磁粉产生团聚。采用机械分散和表面改性的方式对粉体进行分散,并分析粉体分散对粉体粒度、形貌及磁性能的影响。实验表明,经振磨分散,磁粉中超细颗粒分散均匀,有...经湿磨及干燥工序后,铁氧体磁粉颗粒被解碎成单畴颗粒,由于液桥力的作用,磁粉产生团聚。采用机械分散和表面改性的方式对粉体进行分散,并分析粉体分散对粉体粒度、形貌及磁性能的影响。实验表明,经振磨分散,磁粉中超细颗粒分散均匀,有利于磁体成型和取向,成型过程中超细颗粒未发生团聚现象。粉体经分散处理后,在轧制成型粘结磁体中的最大含粉量从90.3%提高至93.7%,剩磁从263 m T提高到273 m T。展开更多
Tantalum nitride powders with particle size of 20-50 nm were prepared by the homogeneous reduction in liquid ammonia,and were treated at the temperature range from 500 ℃ to 1 170 ℃. The results of XRD analysis indic...Tantalum nitride powders with particle size of 20-50 nm were prepared by the homogeneous reduction in liquid ammonia,and were treated at the temperature range from 500 ℃ to 1 170 ℃. The results of XRD analysis indicate that the powders heated up to 500 ℃ are in the form of amorphous. The powder heated at 600 ℃ tends to transform into crystal,the powder heated to temperatures higher than 700 ℃ is clearly of crystal. The results of surface area analysis by BET show that the surface area of the powder increases as the heating temperature increases,and reaches a maximum value of 21.8 m2/g at the heating temperature around 700 ℃.展开更多
文摘生产各向异性轧制磁体用铁氧体磁粉,通常采用的氧化铁Fe_2O_3与氧化锶SrO的摩尔比低于铁氧体摩尔比理论值6.0。由于碱性环境下容易生成Cr^(6+),需通过回火后湿式表面处理工序去除Cr^(6+)。通过调整预烧工艺参数,考察摩尔比在5.65~6.5时磁粉中的Cr^(6+)含量,并探究省去表面处理工序的可能性。研究发现摩尔比大于6.2时,Cr^(6+)含量<10 ppm。摩尔比在5.9~6.3时,磁粉剩磁>257 m T,内禀矫顽力=270 k A/m。通过调整预烧和添加剂比例,在摩尔比为6.2、添加剂含量3%、1100℃预烧条件下获得磁体剩磁达264 m T的性能。通过对预烧温度对比,在1040~1120℃随预烧温度提高,剩磁逐渐提高,之后继续提高,剩磁逐渐降低。
文摘经湿磨及干燥工序后,铁氧体磁粉颗粒被解碎成单畴颗粒,由于液桥力的作用,磁粉产生团聚。采用机械分散和表面改性的方式对粉体进行分散,并分析粉体分散对粉体粒度、形貌及磁性能的影响。实验表明,经振磨分散,磁粉中超细颗粒分散均匀,有利于磁体成型和取向,成型过程中超细颗粒未发生团聚现象。粉体经分散处理后,在轧制成型粘结磁体中的最大含粉量从90.3%提高至93.7%,剩磁从263 m T提高到273 m T。
基金Project(2003AA302430) supported by the National Hi-tech Research and Development Program of Chinaproject(50374007) supported by the National Natural Science Foundation of China
文摘Tantalum nitride powders with particle size of 20-50 nm were prepared by the homogeneous reduction in liquid ammonia,and were treated at the temperature range from 500 ℃ to 1 170 ℃. The results of XRD analysis indicate that the powders heated up to 500 ℃ are in the form of amorphous. The powder heated at 600 ℃ tends to transform into crystal,the powder heated to temperatures higher than 700 ℃ is clearly of crystal. The results of surface area analysis by BET show that the surface area of the powder increases as the heating temperature increases,and reaches a maximum value of 21.8 m2/g at the heating temperature around 700 ℃.
