Effect of PyC interface phase on the cyclic ablation resistance and flexural properties of two-dimensional Cf/HfC composites

Composites based on hafnium carbide and reinforced with continuous naked carbon fiber with and without PyC interface were prepared at low temperature by precursor infiltration and pyrolysis and chemical vapor deposition method. The microstructure, mechanical property, cyclic ablation and fiber bundle push-in tests of the composites were investigated. The results show that after three times ablation cycles, the bending strength of samples without PyC interface decreased by 63.6 %; the bending strength of samples with PyC interface only decreased by 37.8 %. The force displacement curve of the samples with PyC interface presented a well pseudoplastic deformation state. The mechanical behavior difference of two kinds of composites was due to crucial function of PyC interface phase including protection of fiber and weakening of fiber/matrix interface.     

碳/碳复合材料CVI工艺中热解碳形成机理的研究

对碳碳复合材料CVI或（CVD）工艺中热碳组织的类型，沉积机理等研究情况进行了简要的综述，并对其进一步研究提出了相应观点。     

碳/碳复合材料MoSi2/SiC涂层在动态氧化环境下的性能研究

为了考察MoSi₂/SiC防氧化涂层体系在动态氧化环境下的防护能力,对碳/碳复合材料MoSi₂/SiC涂层试样在1100~1500℃下进行了高温燃气高质流冲刷环境下的氧化试验。结果表明,在1100~1500℃的燃气动态环境下,具有稳定的氧化失重速率,氧化失重曲线近似呈直线关系,氧化失重和氧化失重速率均随着氧化温度的升高而降低,表现出该涂层抗高质流冲刷和氧化的能力随温度的升高而提高,在该温度区间内,随着温度的升高,具有更优异的抗氧化和抗高质流冲刷的能力。     

热光双稳态的临界入射功率与临界温升

本文考虑到F—P腔夹层介质和后反射镜均具有一定的吸收时,推导出产生热致色散光学双稳态的临界入射光功率P_c和临界温升△T_c的数学解析表达式。理论计算的 △T_c值与实验值非常符合。为了得到最佳光学双稳态回线和避免腔内的纵向温度梯度,夹层介质和后反射镜应具有一定的匹配吸收。     

电流密度对声电沉积生物活性透钙磷石涂层结构和形貌的影响

通过声电沉积工艺在碳／碳复合材料表面制备了生物活性透钙磷石涂层，采用SEM、FFIR、XRD研究了超声场中电流密度对涂层组成结构和形貌的影响。发现在一定工艺条件下，随电流密度增加，涂层的平均晶粒尺寸减小，致密度增加；当电流密度小于l0mA／cm^2时涂层形貌为片状，l0mA／cm^2-26mA／cm^2时为粒状，32mA／cm^2时为花菜心状。且涂层中透钙磷石晶体的择优取向也发生变化，择优晶面依次为(021)、(111)、(220)。同时还讨论了涂层微观结构变化机理。     

焦炭颗粒的粒度分布及其微观结构研究

焦炭颗粒是生产碳石墨制品的主要原料，它的粒度组成、分布及其微观结构不仅对碳石墨制品的机械性能和理化性能有一定的影响，而且还直接影响到各生产工序的成品率．为此，主要对粉碎后几种焦炭颗粒的粒度组成、分布及其微观结构进行了研究．并通过分析，确立了焦炭颗粒的粒度组成及其分布规律与粉碎方式和焦炭强度之间的内在关系．     

Preparation and characterization of a PMMA/Ce(OH)3, Pr2O3/graphite nanosheet composite

An easy process for the synthesis of poly(methyl methacrylate)/Ce(OH)₃, Pr₂O₃/graphite nanosheet (PMMA/Ce(OH)₃, Pr₂O₃/NanoG) composite was developed. Graphite nanosheets (NanoG) were prepared by treating the expanded graphite with sonication in aqueous alcohol solution. The PMMA/Ce(OH)₃, Pr₂O₃/NanoG composites were prepared via in situ polymerization of MMA monomer in the presence of graphite nanosheets and Ce(OH)₃, Pr₂O₃ through reverse micelle template, in which the methyl methacrylate was designated as the oily phase. The composites were then dispersed with chloroform and coated on glass slides to form films. Scanning and transmission electron microscopy were used to characterize the structure and dispersion of the graphite nanosheets and the composites. The results showed that the high-aspect-ratio structure of the nanosheets played an important role in forming a conducting network in the PMMA matrix. From thermogravimetric analysis, the introduction of graphite nanosheets and inorganic nanopartices exhibited a beneficial effect on the thermal stability of PMMA.     

基于RFID的监狱智能定位系统的设计与实现

为解决在押犯人管理困难的问题,该文介绍了一种基于射频识别技术的CC1110 RSSI定位系统。系统主要由腕带标签、读卡器、无线中继和服务器组成。标签主要负责对读卡器发送相关信息,读卡器负责接收标签的数据并转发给无线中继,中继通过以太网把读卡器传送过来的数据发送给服务器,服务器负责对数据的处理、分析并进行相关管理操作。该系统结构简单、硬件成本较低、易部署、适应性较强。实际测试表明,该系统能够用于监狱在押人员的定位,降低非视距误差。     

液态挤压过程变形特征研究

液态挤压是近几年开发的融液态模锻和热挤压为一体的全新金属成形工艺，本文对其凝固过程、受力状态、变形特征进行了分析，探讨了液态挤压制件的微观组织形貌及正常和非正常组织的成因，在此基础上，对液态挤压的成形规律性问题及保证过程稳定进行的条件提出了独到见解。     

Effect of SiC whiskers on the oxidation protective properties of SiC coatings for carbon/carbon composites

In order to effectively employ the unique high temperature mechanical properties of carbon/carbon composite substrates, SiC coatings reinforced by SiC whiskers were prepared by pack cementation method. The effect of SiC whiskers on the oxidation resistance properties of the single-layer coating and double-layer coating was investigated. SiC whiskers in the single-layer SiC coating have little effect on the anti-oxidation property but obviously improve the thermal shock property. The double-layer coating with inner-layer reinforced coating exhibits more perfect anti-oxidation ability than the double-layer coating with SiC inner-layer coating.