Oxide evolution in NdDy-Fe-B magnet during aging process

Sintered NdDy-Fe-B magnets were made from strip cast flakes by powder metallurgy method. For the magnet with 6wt.% Dy substituted Nd, a remarkable coercivity increase of 70% was obtained after aging at 900°C for 2h and a high coercivity of 23.5 kOe was achieved after aging at 520°C for 2h. The average diameter of the oxide particles decreased during the following 900°C aging treatment. Dy and O diffusion from oxide particles to Nd-rich phase during the aging process was observed. The oxide evolution and Dy element diffusion were helpful to the coercivity enhancement.     

浅议水泥石灰石矿山的优化利用

随着水泥生产规模的不断扩大,石灰石矿山的需求量也在不断增加,要求水泥企业进一步提高矿山石灰石的利用率。制定合理的石灰石矿山优化利用方案是提高石灰石利用率的关键所在。首先分析石灰石矿山的利用原则和优化条件,然后研究石灰石矿山优化的技术措施。结果表明,采用取样检测与在线检测相结合,建立数字化矿山模型等措施能够最大程度地实现石灰石矿山的优化利用。     

氢化度与丙烯腈含量对HNBR硫化胶性能的影响

研究了氢化度和丙烯腈含量对氢化丁腈橡胶(HNBR)硫化特性、力学性能、热老化性能以及热性能的影响。利用核磁共振(NMR)考察了不同型号HNBR橡胶的交联性能;并采用凝胶色谱法(GPC)对生胶的分子量和分子量分布进行了测定,给出了橡胶门尼黏度与其分子量和分子量分布之间的关系。结果表明,随着氢化度与丙烯腈含量的增加,Tg升高;硫化胶的交联密度随着不饱和度和丙烯腈含量的增加而增加;氢化度升高,硫化胶的拉伸强度变化不大,扯断伸长率和撕裂强度降低,100%定伸增加;丙烯腈含量升高,硫化胶的拉伸强度、撕裂强度和100%定伸提高,扯断伸长率变化不大。     

La掺杂CeO_2电子结构的密度泛函计算

根据密度泛函理论(DFT),采用"总体能量平面波"超软赝势方法,对不同La掺杂浓度的CeO_2晶体几何结构进行了优化,从理论上给出了La掺杂CeO_2晶体结构参数及性质,为CeO_2材料的掺杂改性研究提供了理论依据.计算了La掺杂情况下 CeO_2晶体的总体能量、能带结构、总体态密度.分析了La掺杂对CeO_2晶体电子结构的影响.     

医用一次性防护服号型规格检测结果差异探究

本文探究医用一次性防护服松紧带在不施加外力的自然收缩状态和拉伸至极限状态对产品质量检测的影响。选取10件不同号型规格的医用一次性防护服,根据GB 19082—2009标准的要求,分别在样品松紧带不施加外力的自然收缩状态和拉伸至极限状态进行号型规格的检测,并对比松紧带的弹性伸长比。结果发现3件样品的号型规格在松紧带不施加外力的自然收缩状态下合格,拉伸至极限状态不合格;7件样品的号型规格在两种状态下均不合格。该研究旨在提高生产企业与检测机构对医用一次性防护服的相关指标理解的重视程度,为提升检测规范性提供依据与参考。     

Model of temperature field for the preparation process of melt-spun NdFeB powders

Melt-spun ribbons which are the important raw material for hot-deformed magnets can be prepared by single-roller melt-spinning. In order to prepare well-structured ribbons, the model of temperature field for single-roller melt-spinning process was constructed in this work. The heat conduction in this process was simplified as one dimensional heat conduction problem. It was shown by modeling that, the temperature field in the melt-spinning before solidification in this model could be described as this equation T(x,t)=Tmoexp[–k(x–x0)–k2αt]+T0. The temperature T(x,t) of the alloy melts decreased with increased position x and cooling time t exponentially from the wheel-free surface to the wheel-side surface. The constant k determined the decrease speed of alloy temperature T(x,t), which was proportional to the interfacial heat transfer coefficient h and the interfacial area of heat conduction A0, but inversely proportional to the thermal conductivity K. x0 was the thickness of the alloy melt. With increased x0, the temperature difference between wheel-free surface and the wheel-side surface became larger, which would lead to larger difference in grain size. In experiments, the influence of melt-spinning process parameters on the temperature field model was discussed, such as cooling roller materials, wheel speed, and so on. Melt-spun ribbons prepared by single-roller melt spinning at different wheel speed were investigated and magnetic properties of die-upset magnets from melt-spun ribbons on different cooling roller were analyzed. The variation of grain size in the depth direction consisted with temperature field model. This model provided directions for the preparation of melt-spun ribbons with uniformly distributed fine grains, which were very necessary for producing hot-deformed magnets with high magnetic performance.     

中子活化多元素分析仪:有色领域的绿色仪表

正有色金属领域属于高耗能工业领域,其生产环节的节能减排一直是企业降低成本提高竞争力的重要途径,本文针对有色金属的实际应用,介绍了一种有色金属领域的绿色仪表——中子活化多元素分析仪,并简述了其在有色金属领域对节能减排这一难题所起到的实质性作用。随着近年来我国经济的高速发展,工业类能源的消耗也在进一步增加,随之而来的便是对环境的破坏,如何在提高工业产能的同时,进一步节能减排,是有色金属、电力、钢铁、石化等产业一直面临的难题。     

对城市公共交通工作的思考与探索

回顾了运城市公交行业的过去，介绍了经过改革后的现状，着重阐述了运城市公交公司在面临冲击与困扰的低谷中，通过四项重大的改革措施，顽强拼搏，落实强硬措施，从而走出困境，走向振兴的过程。提出只要具有超前的思路和改革的举措，就能找开新局面，重振企业雄风。     

基于量子粒子群算法的热电偶动态校准及动态补偿技术研究

为了实现热电偶传感器的动态校准及动态补偿,有效改善热电偶的动态特性,利用半导体激光加热高、加热快的优点,构建了可溯源温度动态校准系统,实现了热电偶的可溯源动态校准,测得了C型热电偶的时间常数。应用量子粒子群优化算法建立了热电偶传感器的动态补偿滤波器模型,有效改善了热电偶的动态特性,减小了热电偶传感器的动态误差。