C／C复合材料石墨化度的测定和评价

用Ｘ射线衍射方法对不同热处理温度下Ｃ／Ｃ复合材料石墨化度进行了测定，并对衍射峰进行了分峰处理。得出该材料由三种不同组元构成，即树脂炭，碳纤维和热解炭，求出各组元的石墨化度值及所占比例，进而得到试样的加权平均石墨化度。     

碳纤维高温处理过程中石墨片层堆叠的温度效应

采用二维广角X-射线衍射法(WAXD)研究了国产聚丙烯腈基碳纤维在高温处理过程中石墨片层结构的堆叠过程,分析了温度因素对于堆叠结构的影响。实验结果表明,随着热处理温度的升高,碳纤维中的类石墨片层堆叠层数不断增加,结构趋于规整致密,并且在1 900℃后堆叠速率加快。同时,通过元素分析和Raman光谱的研究,解释了堆叠速率提高的原因,随着非碳元素的脱除和碳化学结构向SP2杂化转变,结构缺陷不断减少,有利于石墨片层的堆叠。     

Biological features of an early-maturity mutant of sweet sorghum induced by carbon ions irradiation and its genetic polymorphism

It is well known that heavy ions irradiation is characterized by a high linear energy transfer (LET) and relative biological effectiveness (RBE). These characters are believed to increase mutation frequency and mutation spectrum of plants or mammalian cells irradiated by heavy ions. Here we describe an early-maturity mutant of sweet sorghum induced by carbon ion irradiation. The growth period of this mutant was shortened by about 20 days compared to the wild type. The proline content of the mutant was increased by 11.05% while the malondialdehyde content was significantly lower than that of wild type. In addition, the RAPD analysis indicated that the percentage of polymorphism between the mutant KFJT-1 and the control KFJT-CK reached 5.26%. The gain of early-maturity might solve the problem in the northwest region of China where seeds of sweet sorghum cannot be mature because of early frost. The early-maturity mutant may be important for future space cultivation.     

Protective effects of melatonin against C beam irradiation-induced oxidative stress and DNA injury in the mouse brain

The purpose of this experiment was to estimate the protective effects of melatonin against radiation-induced brain damages in mice induced by heavy ion beams. Kun-Ming mice were randomly divided into five groups: normal control group, irradiation control group, and three different doses of melatonin (5, 10, and 20 mg/kg, i.p.) treated groups. Apart from the normal control group, the other four groups were exposed to whole-body 4.0 Gy carbon ion beam irradiation (approximately 0.5 Gy/min) after i.p. administration of normal saline or melatonin 1 h before irradiation. The oxidative redox status of brain tissue was assessed by measurement of malondiadehyde (MDA) levels, total superoxide dismutase (T-SOD), cytosolic superoxide dismutase (Cu/ZnSOD, SOD1) and mitochondrial superoxide dismutase (MnSOD, SOD2) activities at 8 h after irradiation. DNA damages were determined using the Comet assay and apoptosis and cell cycle distribution were detected by flow cytometric analyses. A dramatic dose-dependent decrease in MDA levels, tail moment, rates of tailing cells, and apoptosis, and a dose-dependent increase in T-SOD and SOD2 activities, in brain tissues in the melatonin-treated groups were detected compared with the irradiation only group. Furthermore, flow cytometric analysis demonstrated that the percentage of brain cells in the G0/G1 phase decreased significantly, while those in the S and G2/M stage increased dramatically, with mice pretreated with melatonin compared to the irradiation control group. These data indicate that melatonin has protective effects against irradiation-induced brain injury, and that its underlying protective mechanisms may relate to modulation of oxidative stress induced by heavy ionirradiation.     

碳纳米管在吸波材料中的研究与应用

碳纳米管是一种有前途的微波吸收剂,可以作为潜在的隐身材料、电磁屏蔽材料或暗室吸波材料使用.本文综述了近年来国内外通过碳纳米管碳化学镀改性、纳米管与聚合物共混、纳米管与铁磁材料杂化来制备微波吸收剂的研究成果和存在的问题,提出了碳纳米管作为吸波材料今后的发展方向.     

Enhanced electrothermal effect of carbon fibrous composites decorated with high conductive carbon nanotube webs

Literature has demonstrated that Carbon Nanotubes (CNTs) can greatly enhance the electrical conductivity and matrix-dominated mechanical properties of fibrous composites. However, electrothermal coupling effect of CNTs on Carbon Fiber Reinforced Plastics (CFRPs) has scarcely been considered. This work prepared and introduced thin and porous CNT webs to the surface or/and interface of a CFRP to enhance its electrothermal properties. The results show that CNT webs can enhance the transverse electrical conductivities of the CFRP by 231%−519% in a current range of 50–150 mA, when compared to the base-CFRP. Also, the surface temperature of CNT webs decorated CFRP can be improved by 20.5–32.3 °C within 3 min showing a self-heating rate of 6.8–10.8 °C/min just with an applied voltage of 20–30 V, increased by 152%−177% when compared to the base-CFRP (2.7–3.9 °C/min). Also, deicing can be finished within 4–10 min with a voltage of 18 V and an input power of 246 W/m². Moreover, the electrothermal processes nearly have no negative effect on the mechanical properties of the CFRP. The relatively low input power and short response time for deicing make the CNT webs decorated CFRP may be a potential new generation for aeronautical deicing structure.     

三向碳-碳复合材料界面结构研究

本文用透射电子显微术研究了三向碳-碳复合材料的界面结构。结果表明:在碳纤维表面微缺陷区或活性区,存在沉积碳微晶条带“钉扎”结构;在碳纤维表面光滑区,存在一定数量的界面间隙:沥青碳与沉积碳的界面存在一个沉积碳微晶条带与沥青碳石墨条带相互贯穿网络所形成的诱导结构界面相。本文分析了界面缺陷,并讨论了界面结构对纤维束断裂行为的影响。     

碳纤维复合材料气瓶的X射线实时成像技术

针对某型号卫星用碳纤维复合材料气瓶的结构特点,分析了其常见缺陷及其对复合材料性能的影响,运用射线实时成像技术进行在线动态检测,取得了较好的效果.     

Kinetic temperature and carbon dioxide from broadband infrared limb emission measurements taken from the TIMED/SABER instrument

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment is one of four instruments on NASA’s Thermosphere–Ionosphere–Energetics and Dynamics (TIMED) satellite. SABER measures broadband infrared limb emission and derives vertical profiles of kinetic temperature (Tk) from the lower stratosphere to approximately 120 km, and vertical profiles of carbon dioxide (CO₂) volume mixing ratio (vmr) from approximately 70 km to 120 km. In this paper we report on SABER Tk/CO₂ data in the mesosphere and lower thermosphere (MLT) region from the version 1.06 dataset. The continuous SABER measurements provide an excellent dataset to understand the evolution and mechanisms responsible for the global two-level structure of the mesopause altitude. SABER MLT Tk comparisons with ground-based sodium lidar and rocket falling sphere Tk measurements are generally in good agreement. However, SABER CO₂ data differs significantly from TIME-GCM model simulations. Indirect CO₂ validation through SABER-lidar MLT Tk comparisons and SABER-radiation transfer comparisons of nighttime 4.3 μm limb emission suggest the SABER-derived CO₂ data is a better representation of the true atmospheric MLT CO₂ abundance compared to model simulations of CO₂ vmr.     

碳纤维复合材料在发射装置上的应用研究

机载弹射发射装置轻量化设计是现阶段机载武器系统重要的研究课题和难题,碳纤维复合材料应用于制造具有复杂外形的承力结构件,对于航空武器的轻量化设计具有重要意义。选取机载弹射发射装置的典型结构作为研究对象,首先通过结构优化设计和RTM成型工艺获得复合材料结构件;然后,经过各项结构件的试验和整机试验验证,结合应变测量数据,证明其强度满足设计要求,且获得了显著的减重效果。通过对复合材料典型结构件的研究,为其在发射装置领域的应用提供理论指导和依据。