Fine-grained Nd10.79Pr2.8Al0.4B7.72Fe78.29 magnets were prepared by low temperature pre-sintering and subsequent hot pressing. The grain size of the magnets is just about 1–3 μm because the low sintering temperature...Fine-grained Nd10.79Pr2.8Al0.4B7.72Fe78.29 magnets were prepared by low temperature pre-sintering and subsequent hot pressing. The grain size of the magnets is just about 1–3 μm because the low sintering temperature results in no grain growth. The orientation degree, microstructure, and magnetic properties were studied. Some grains＇ easy axes deviate from the orientation direction, possibly due to grain rotation during the hot pressing. By subsequent annealing, the magnetic properties were significantly enhanced. Especially, the squareness of the demagnetization curve was improved greatly.The enhancement of coercivity by annealing can be explained by an improvement of both grain boundaries and magnetic isolation, which decouples the exchange interaction between neighboring grains.展开更多
The microstructure and characteristics of pre-sintered strontium ferrite powder were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The present study shows that t...The microstructure and characteristics of pre-sintered strontium ferrite powder were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The present study shows that the pre-sintered strontium ferrite powder is provided with a certain particle size distribution, which results in high-density magnets. The strontium ferrite particle has a laminar hexagonal structure with a size similar to ferrite single domain. Ferric oxide phase due to an incomplete solid phase reaction in the first sintering is discovered, which will deteriorate the magnetic properties of ferrite magnet. In addition, the waste ferrite magnets with needle shape arranging along C axis in good order into the powders are found, which have no negative effects on finished product quality.展开更多
[目的]烧结钕铁硼(Nd Fe B)的电镀前处理技术还不够成熟,开发适宜的前处理工艺极其重要。[方法]在电镀铜前,先采用以羟基乙叉二膦酸(HEDP)为主配位剂的溶液对NdFeB进行预浸。预浸液组成和工艺条件为:HEDP 20~30 g/L,氢氧化钾20~25 g/L,...[目的]烧结钕铁硼(Nd Fe B)的电镀前处理技术还不够成熟,开发适宜的前处理工艺极其重要。[方法]在电镀铜前,先采用以羟基乙叉二膦酸(HEDP)为主配位剂的溶液对NdFeB进行预浸。预浸液组成和工艺条件为:HEDP 20~30 g/L,氢氧化钾20~25 g/L,碳酸钾10~15 g/L,葡萄糖酸钾1~2 g/L,乙酸0.5~1.0 g/L,室温,时间60 s。通过电化学测试对比了Nd Fe B基体有无预浸处理时,铜在其表面的电沉积行为,并通过金相显微镜、扫描电镜、能谱仪和荧光光谱测厚仪,对比了有无预浸处理的Nd FeB基体表面Cu镀层的宏观和微观表面形貌、截面形貌、元素分布及厚度分布均匀性。[结果]Nd Fe B基体预浸后表面被活化,静态电位降低。预浸液能够填满基体表面的孔隙并形成一层水薄膜,在后续电镀铜时保护基体不被腐蚀。预浸处理的Nd Fe B基体表面所得Cu镀层均匀、致密,不易氧化发黑,结合力和耐蚀性较好。[结论]对烧结钕铁硼进行预浸处理,能够保证其在后续电镀铜过程不被腐蚀,提高Cu镀层的综合性能。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51101167)the National Science and Technology Major Project,China(Grant No.2012ZX02702006-005)+2 种基金the Local Cooperation Project of Chinese Academy of Sciences(Grant No.DBSH-2011-013)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ14E010007)the Natural Science Foundation of Ningbo,China(Grant No.2014A610161)
文摘Fine-grained Nd10.79Pr2.8Al0.4B7.72Fe78.29 magnets were prepared by low temperature pre-sintering and subsequent hot pressing. The grain size of the magnets is just about 1–3 μm because the low sintering temperature results in no grain growth. The orientation degree, microstructure, and magnetic properties were studied. Some grains＇ easy axes deviate from the orientation direction, possibly due to grain rotation during the hot pressing. By subsequent annealing, the magnetic properties were significantly enhanced. Especially, the squareness of the demagnetization curve was improved greatly.The enhancement of coercivity by annealing can be explained by an improvement of both grain boundaries and magnetic isolation, which decouples the exchange interaction between neighboring grains.
基金This work was financially supported by the Key Technologies R&D Program of Guangdong Province, China (No. 2004B10301009).
文摘The microstructure and characteristics of pre-sintered strontium ferrite powder were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The present study shows that the pre-sintered strontium ferrite powder is provided with a certain particle size distribution, which results in high-density magnets. The strontium ferrite particle has a laminar hexagonal structure with a size similar to ferrite single domain. Ferric oxide phase due to an incomplete solid phase reaction in the first sintering is discovered, which will deteriorate the magnetic properties of ferrite magnet. In addition, the waste ferrite magnets with needle shape arranging along C axis in good order into the powders are found, which have no negative effects on finished product quality.
文摘[目的]烧结钕铁硼(Nd Fe B)的电镀前处理技术还不够成熟,开发适宜的前处理工艺极其重要。[方法]在电镀铜前,先采用以羟基乙叉二膦酸(HEDP)为主配位剂的溶液对NdFeB进行预浸。预浸液组成和工艺条件为:HEDP 20~30 g/L,氢氧化钾20~25 g/L,碳酸钾10~15 g/L,葡萄糖酸钾1~2 g/L,乙酸0.5~1.0 g/L,室温,时间60 s。通过电化学测试对比了Nd Fe B基体有无预浸处理时,铜在其表面的电沉积行为,并通过金相显微镜、扫描电镜、能谱仪和荧光光谱测厚仪,对比了有无预浸处理的Nd FeB基体表面Cu镀层的宏观和微观表面形貌、截面形貌、元素分布及厚度分布均匀性。[结果]Nd Fe B基体预浸后表面被活化,静态电位降低。预浸液能够填满基体表面的孔隙并形成一层水薄膜,在后续电镀铜时保护基体不被腐蚀。预浸处理的Nd Fe B基体表面所得Cu镀层均匀、致密,不易氧化发黑,结合力和耐蚀性较好。[结论]对烧结钕铁硼进行预浸处理,能够保证其在后续电镀铜过程不被腐蚀,提高Cu镀层的综合性能。
