碳纤维用PAN原丝超声波水洗新技术

为降低PAN原丝中的DMSO(二甲基亚砜)残留量,减少其对原丝的拉伸、预氧化处理等过程的不利影响而造成的碳纤维的结构缺陷、强度降低,将超声波水洗技术应用到PAN原丝水洗工艺中.结果证明,新方法明显提高了水洗效果,能够快速有效地降低原丝中DMSO残留量.     

吸气模式激光推进空气等离子体光谱

利用实验室自行研制的紫外预电离CO2激光器进行了激光等离子体实验,实验采用底面直径均为60mm,焦距分别为5 mm和10 mm的两种抛物面光船。介绍了激光等离子体光谱和明显的特征谱线,以及激光等离子体温度估计模型;分析了两种光船对激光等离子体的影响。实验表明:相同底面直径10 mm焦距光船产生的等离子体信号峰值和持续时间均略大于5 mm焦距光船;10 mm焦距光船产生的等离子体温度明显高于5 mm的,最大温度产生时间比5 mm光船要晚一些。     

镀钴碳纳米管/环氧树脂基复合材料的制备及其微波吸收特性研究

采用化学镀法制备了表面镀钴的多壁碳纳米管，并将其均匀分散在环氧树脂基体中固化成膜，形成镀钴碳纳米管／环氧树脂基复合材料。采用透射电镜、X射线衍射及振动样品磁强计等对镀钴碳纳米管的形貌、微结构与磁性能进行了表征，还采用数字化网络分析仪对该复合材料在0．5～40GHz频段内的微波吸收特性进行了研究。结果表明：在相同的碳管质量分数(1％)和吸波介质层厚度(2．0mm)等条件下，与纯碳纳米管相比，表面镀钴碳纳米管的吸收峰往高频方向移动，吸收强度略有增加，但吸收频带并没有宽化趋势。     

环氧树脂基导电复合材料力电性能研究

实验研究了填充炭黑的环氧树脂基导电复合材料的导电机理,不同炭黑掺量复合材料在一次加载及反复加载卸载下的力电效应。结果表明,炭黑掺量为20%试件的力电效应明显且稳定;各掺量试件卸载后均存在较大残余电阻,经多次加载卸载后,电阻变化率逐渐减小并趋于稳定值;卸载后电阻恢复率不断增加,最终可完全恢复。     

无纬碳布增强针刺毡C/C复合材料性能的研究

比较了几种不同工艺制备的针刺毡C/C复合材料。对针刺碳毡织物首先进行预增密处理,得到初始密度和碳纤维含量较高的坯料,然后用树脂浸渍法进一步致密化。研究表明,用该方法制备的C/C复合材料比未经预处理的试样,拉伸强度提高39%,压缩强度提高14%,层间剪切强度提高36%。通过SEM观察和常温力学性能的测试,分析表明工艺的改进是强度提高的主要原因。     

碳纤维增强陶瓷基复合材料抗氧化涂层研究进展

对碳纤维增强陶瓷材料抗氧化涂层的要求、组成与制备工艺以及最近抗氧化涂层体系的发展做了综述。并且对今后抗氧化涂层的发展作了一些展望。     

高能CO2激光腔镜高反介质薄膜的传输特性

为了获得适用于高能CO2激光器的高抗破坏阈值高反薄膜,以10.6μm高反膜ZnSe/YbF3,PbTe/BaF2膜系为例,数值模拟了激光在高反介质膜中的传输的场特性;给出了激光在多层介质膜中的场强分布、温度场分布及热应力分布。结果表明硅镜基体上的PbTe/BaF2膜系所需膜层厚度小、膜层数少,反射率可高达99.98%。     

复合材料薄壁加筋抛物面天线仿真与优化

采用Patran/Nastran有限元软件对复合材料薄壁加筋抛物面天线进行了建模和仿真分析。重点分析了反射面铺层方式、加筋结构形式以及加强筋铺层对抛物面天线基频的影响。分析结果表明:采用[0/45/-45/90]s铺层形式的反射面基频最高;增加径向和环向筋可大幅提高天线基频,其中加筋结构采用[0/30/90/-30]s铺层可进一步提高天线基频。通过有限元分析确定了基频最佳的复合材料抛物面天线结构,为制备薄壁加筋抛物面天线提供了指导。     

Grinding temperature and energy ratio coefficient in MQL grinding of high-temperature nickel-base alloy by using different vegetable oils as base oil

Vegetable oil can be used as a base oil in minimal quantity of lubrication(MQL). This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force,and a clip-type thermocouple was used to determine grinding temperature. The grinding force, grinding temperature, and energy ratio coefficient of MQL grinding were compared among the seven vegetable oil types. Results revealed that(1) castor oil-based MQL grinding yields the lowest grinding force but exhibits the highest grinding temperature and energy ratio coefficient;(2) palm oil-based MQL grinding generates the second lowest grinding force but shows the lowest grinding temperature and energy ratio coefficient;(3) MQL grinding based on the five other vegetable oils produces similar grinding forces, grinding temperatures, and energy ratio coefficients, with values ranging between those of castor oil and palm oil;(4) viscosity significantly influences grinding force and grinding temperature to a greater extent than fatty acid varieties and contents in vegetable oils;(5) although more viscous vegetable oil exhibits greater lubrication and significantly lower grinding force than less viscous vegetable oil, high viscosity reduces the heat exchange capability of vegetable oil and thus yields a high grinding temperature;(6) saturated fatty acid is a more efficient lubricant than unsaturated fatty acid; and(7) a short carbon chain transfers heat more effectively than a long carbon chain. Palm oil is the optimum base oil of MQL grinding, and this base oil yields 26.98 N tangential grinding force,87.10 N normal grinding force, 119.6 °C grinding temperature, and 42.7% energy ratio coefficient.