真空热处理提高烧结钕铁硼镀Cu层结合力的研究

目的提高烧结钕铁硼表面镀Cu膜层结合力,改善可焊性,进一步制备生物友好的强耐蚀性防护薄膜。方法采用磁控溅射技术在钕铁硼表面制备约7μm厚的Cu膜,研究热处理温度和时间对Cu/NdFeB界面组织、膜基结合力和样品磁性能的影响,选取最优化热处理样品电镀约2μm厚的Sn膜,再于280℃在其表面焊接Au片,评估其可焊性。结果 500℃热处理样品的Cu膜与基体间发生了明显扩散,扩散深度及结合力随时间延长而增加。热处理2 h样品的膜基结合力由处理前的11.0 MPa提高至31.5 MPa,膜基分离位置发生在磁体亚表面层,矫顽力、剩磁和最大磁能积等磁性能无显著下降。进一步镀Sn后,在其表面焊接的Au层与Cu膜层基体冶金结合良好,耐腐蚀性能优异。700℃热处理样品的Cu膜与基体间扩散过快,易造成Cu膜消失及钕铁硼基体表面损伤。结论真空热处理温度和时间对Cu/钕铁硼界面组织有根本性影响,通过适宜的热处理可大幅提高磁控溅射的Cu膜与烧结钕铁硼之间的膜基结合力,同时不明显降低磁性能,可采用焊接方法在热处理后的Cu膜表面制备结合力高、长效耐蚀且生物友好的防护薄膜

2008年-2012年山东半岛海域浒苔时空分布特征研究/Research on the Characteristics of Ulva .Proli f era in Shandong Peninsula During 2008-2012 Based on MODIS Data[J]

浒苔是我国近海一种新型的海洋生态灾害，自2008年以来，每年5-8月份在黄海海域周期性暴发与消亡，给沿海地区造成不同的环境影响和经济损失。基于2008年-2012年五年的M ODIS数据，计算了山东半岛海域长时间序列NDVI ，利用阈值分割法提取浒苔信息，并进一步获得爆发的时间、面积、相对聚集密度、影响范围及浒苔漂浮路径。结果表明：2008年以来各年浒苔最早发生在5月中旬至6月上旬，6月中旬至7上旬进入爆发期，浒苔面积、影响范围及浒苔密度达到最大值，其相对聚集密度峰值一般早于或晚于爆发期一个生长阶段，最终于7月下旬或8月上旬进入消亡期，平均持续时间约为71天。浒苔漂浮路径整体为从东南外海逐渐开始向西北近海海域靠近。从浒苔面积、影响范围、相对聚集密度等多项指标综合看，2008年和2009年两年浒苔爆发较为严重

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies