高取向度石墨基复合材料力学性能及微观结构研究

以Zr B2和Si C为烧结助剂,采用流延-叠层-热压工艺制备高取向石墨基复合材料,并对其抗弯强度、断裂韧性、断裂行为以及微观结构进行了研究。结果表明:该石墨基复合材料结构完整,其中片状石墨颗粒平行热压面高度定向排列。弯曲强度和断裂性能及致密度都得到大幅度提高,垂直片层和平行片层方向测试的抗弯强度和断裂韧性分别为104 MPa、2.07 MPa·m1/2和84 MPa、1.97 MPa·m1/2。高取向石墨基复合材料受到不同方向力冲击时的断裂行为显著不同,垂直层面加压时断裂由脆性破坏变为非脆性破坏行为,断裂功达到145 J/m2为平行层面测试的2倍。非脆性破坏行为主要归因于层界和高度定向的片状石墨颗粒诱导裂纹偏转分叉以及片状石墨颗粒桥联拔出。

静电纺自集束法制备高取向度纤维

采用线性螺旋金属丝取代传统的针式纺丝喷头,利用静电纺丝方法制备了聚丙烯腈(PAN)纳米纤维。通过添加四正丁基溴化铵调节了纺丝液的电学性能。观察了纺丝过程中纺丝电流大小及射流运动轨迹,并对所纺纤维形貌及力学性能进行了表征与测试。实验结果表明,当四正丁基溴化铵的质量浓度为1.5%,纺丝电流大小为0.15~0.25mA时,射流的飞行轨迹从发散型变成集束型,射流集束现象明显,纤维取向度较好;纤维平均直径为920nm,纤维拉伸强度提高了近4倍。

聚酰胺66高取向度纤维的性能和应用

新型高取向低收缩聚酰胺66纤维具有高取向度、低热收缩率、高耐热性能和较好的耐疲劳性能,因此受到轮胎行业高端用户的青睐。介绍了高取向低收缩聚酰胺66纤维的应用前景,认为其作为骨架材料不仅满足了轮胎轻量化、增强安全性等绿色用途,同时用于缆绳、输送带和吊装带也提高了安全性能。

室温下脉冲激光沉积制备高取向度AlN薄膜

用脉冲激光沉积（PLD）方法，在p-Si（100）衬底上、室温下和不同N2氛围中制备了高度取向的A1N薄膜，并利用X射线衍射（XRD）仪、傅立叶变换红外（FTIR）光谱仪和扫描电子显微镜（SEM）对样品的特征进行了研究。结果表明，在从5×10^-6～5．0Pa的N2气压范围内，制备的薄膜都呈现h＜100〉晶向，并且随着气压的升高，样品的结晶度有明显的提高。另外，随着N2浓度的增大，Al-N键的结合度增强，AlN晶粒的尺寸增大，在样品表面出现杂散晶粒，薄膜的粗糙度增大。

BN织构陶瓷的制备与力学性能研究

以片状的BN为基体粉料,采用流延成型工艺结合热压烧结制备BN织构陶瓷,并对其结构、断面形貌以及力学性能进行了研究。实验结果表明,BN晶粒选择沿(002)晶面择优定向排列。织构陶瓷的力学性能呈现出明显的各向异性:当加载方向垂直于片层时,弯曲强度和断裂韧性分别为53.75 MPa和1.51 MPa·m^(1/2),均优于水平方向的力学性能。垂直方向上良好的性能归因于加载时片状颗粒引起的裂纹偏转。

An orientation method and analysis of optical radiation sources based on polyhedron and parallel incident light

The spatial orientation of optical radiation sources has long been the hot topic in the aerospace and the military applications.Current researches mainly focus on the high precision orientation on the partial field of view.Thus,combination of several partial fields of view is required to achieve orientation when the field of view exceeds 180°,which results in the increase of size,weight,power consumption and the cost.By defining radiation energy and direction of the optical radiation source as a vector and applying the cosine law of radiation and vector theorem,it is shown that the vector can be obtained from unit normal vectors on the three un-coplanar surfaces and from the energy projected by the optical radiation source.Based on this,an orientation method with 360° full field of view by a polyhedron is suggested,the mathematical formula for anti-multipath interference is supposed and the error upper limit is derived.The feasibility and effectiveness of this method are validated by measurements and simulation.An accuracy better than 2.866° and 0.574° is achieved when the ratio of measurement error of energy on arbitrary surface and the true value are 5% and 1%,respectively,given the matrix composed of unit normal vectors on three measurement surfaces is orthogonal.