粉煤灰微珠表面包覆机理研究

描述了微珠-氢氧化钙溶液体系中复合微珠的制备和表征方法.探讨了95℃恒温状态下氢氧化钙含量、微珠中活性组分随反应时间的变化规律.分析了体系温度和反应时间对包覆层生长过程的影响,结果表明：体系温度和反应时间是加速氢氧化钙对微珠产生水化作用的重要参数,两者之间具有协同效应;体系温度越高,所需反应时间越短,反之亦然.根据反应体系中氢氧化钙最强衍射峰强的变化规律,研究了微珠表面包覆层生长机制和包覆机理.结果表明：包覆层生长过程经历了诱导期、加速期、稳定期和颗粒快速生长期4个阶段.     

Mechanical Properties of Engineered Cementitious Composites with High Volume Fly Ash

In order to improve the mechanical properties and Greenness of engineered cementitious composites (ECC),four-point bending test,compressive strength and flexural strength test were employed to analyze the effects of fly ash content on the mechanical properties of.ECC.The replacement ratio of cement with fly ash was 50%,60%,70% and 80%,respectively.The experimental results indicate that ECCs with high volume fly ash still remained the characteristic of pseudo-strain hardening and the mid-span deflection in four-point bending test increase remarkably by adding more fly ash.The observations of ECCs indicate that the multiple cracks are saturated and the crack width is relatively smaller for higher volume fly ash ECC,owing to the lower strength of matrix and the improvement ofinterface bonding.Fly ash reduces the compressive strength and flexural strength of ECC at all ages.Therefore,as the compressive strength could meet the requirement of practical engineering,employing the higher volume fly ash ECCs would benefit to obtain relatively high ductility.     

粉煤灰掺量对磷酸镁水泥基复合材料力学性能影响

研究了粉煤灰掺量对磷酸镁水泥基材料的抗压强度、抗折强度、耐磨性和膨胀性能的影响。实验结果表明,随着粉煤灰掺量的增加,磷酸镁水泥净浆的抗压强度先增大后下降,粉煤灰掺量为胶凝材料质量的10%时,抗压强度最大;而材料的抗折强度和耐磨性能随着粉煤灰掺量的增加而下降。其膨     

加筋粉煤灰路用性能模型试验研究

建立了加筋粉煤灰路堤的室内模型,通过不同层厚的碾压工艺,承载板,弯沉及冲击破坏等试验和检测,对加筋粉煤灰路堤的变形特性、稳定性、施工压实工艺及加筋的必要性和作用机理进行了研究,得出了层厚与碾压遍数的关系,强度和变形随养生时间的变化规律,松铺系数的推荐值.试验结果表明,粉煤灰路堤养生28天后强度明显提高,变形明显降低,3∶7粉煤灰的松铺系数在1.114~1.16之间.改良后的加筋粉煤灰路堤可满足二级以上公路设计技术要求,且水稳定性良好.     

Mineralogical and Active Mechanical Excitation Characteristics of Filled Fly Ash Cementitious Materials

To reveal the influence of mechanical activation on the performance of fly ash, the microanalysis(the energy spectroscopy, XRD and SEM), the distribution size of particle of fly ash and cement paste intensity of various age for different grinding time were studied. The relationships of the activity and the composition of fly ash, microstructure and the distribution of particle size by mechanical activation of fly ash were obtained. The internal glass beads with activity were released by grinding fly ash for a certain time. The particle specific surface area was improved and the hydration reaction of the interface and the surface active center was increased by grinding. The granularity distributing of fly-ash trended towards optimization. The polar molecules or ions were easier to intrude into the internal cavity of the vitreous body. The active silica and alumina of fly ash were rapidly depolymerized. Each performance index of fly ash was increased before grinding for 20 min. Cement paste intensity of various age increased along with the grinding time, and the early strength increase range was big, but the later period intensity increase range hastened slightly. The internal part of vitreous of fly ash was destroyed if the fly ash continued to be ground and the activity of fly ash was reduced. It is suggested that Guozhuang's fly ash should be ground for 20 min.     

大掺量粉煤灰超高性能钢纤维混凝土的静动态力学行为

研究了4种不同钢纤维掺量(体积掺量分别为0%,1.0%,1.5%,2.0%)的大掺量粉煤灰超高性能混凝土的单轴压缩强度、弹性模量、单轴抗拉强度、弯曲韧性、断裂韧性、断裂能等静态力学行为,以及高速冲击、压缩作用下的应力波传播规律、应力–应变曲线和破坏特征等动态力学行为.结果表明:掺加钢纤维的大掺量粉煤灰超高性能混凝土的轴心抗压强度、弹性模量和抗拉强度略有增大,韧性指数、残余强度、断裂韧度和断裂能成倍提高;未能增加冲击、压缩作用下的应变率效应程度,但却增大动态应力–应变曲线下的面积,提高试件破坏的应变率阈值,使混凝土存在裂而不散的破坏现象.     

粉煤灰吸附特性研究

在粉煤灰理化特性分析的基础上,对粉煤灰进行了物理激发和化学激发.研究结果表明：物理激发和化学激发均能提高粉煤灰的吸附活性.化学激发方法在反应温度为90℃、反应时间为12h、灰钙比为5、水固比为15时,粉煤灰的吸附活性提高最大.     

粉煤灰基地质聚合物/水泥复合材料的力学性能

以粉煤灰和水玻璃粉体为原料制备地质聚合物干粉材料,研究不同粉煤灰基地质聚合物干粉掺量对粉煤灰基地质聚合物/水泥复合材料力学性能的影响,通过XRD和SEM分析粉煤灰和粉煤灰基地质聚合物/水泥复合材料的物相组成和微观结构。结果表明,粉煤灰基地质聚合物干粉掺量从0增加到60%,复合材料的抗折强度和抗压强度减少,折压比增加,主要是因为粉煤灰基地质聚合物常温下反应时间长,随着粉煤灰基地质聚合物干粉掺量的增加,反应产物中地质聚合物凝胶比例增加,90d后试样的折压比增加。     

玄武岩纤维布增强环氧树脂复合材料研究

以玄武岩纤维平纹布 (BF) 加入到环氧树脂 (EP) 中,采用模压工艺制备BF／EP 复合材料,研究加入不同层数的玄武岩纤维布对复合材料力学性能和断裂韧性的影响。实验结果表明,BF/EP复合材料的弯曲强度、冲击强度和断裂韧性明显优于环氧树脂;与未加BF的环氧树脂相比,加入三层BF后复合材料的弯曲强度提高了2.76倍,缺口冲击强度提高了19.67倍,无缺口冲击强度提高了5.94倍,KIC提高了2.97倍。     

电厂粉煤灰筑坝的物理力学性质研究

介绍四座电厂粉煤灰作为筑坝材料的物理性质,静力强度指标,动力液化强度及动剪模和阻尼特性.     

碳纤维/环氧树脂复合材料摩擦性能研究

采用液相氧化法合成氧化碳纤维,制备碳纤维/环氧树脂复合材料,研究了复合材料的力学性能和摩擦性能。结果表明,碳纤维经液相氧化后,复合材料的力学强度有所降低,但模量均有明显提高;碳纤维和氧化碳纤维能改善环氧树脂复合材料的摩擦性能,降低摩擦系数和减少磨损率,提高复合材料的耐磨性;复合材料的摩擦系数和磨损率均随着载荷和时间的增加而增大。由材料磨损表面的扫描电镜可知碳纤维/环氧树脂复合材料以磨粒磨损与粘着磨损为主,氧化碳纤维/环氧树脂复合材料以疲劳磨损和磨粒磨损为主。碳纤维和氧化碳纤维可以作为环氧基摩擦材料的增强材料,这一研究对于拓宽摩擦材料领域的研究发展具有重要意义和促进作用。     

石墨烯增强铝基复合材料制备及力学性能研究

针对石墨烯在铝基体中分散不均匀的问题,采用电荷吸引的方法,将用Hummers法制备的带负电荷氧化石墨烯加入到表面处理后带有正电荷的铝粉中,得到氧化石墨烯/铝复合粉末,最后采用粉末冶金制备出石墨烯增强铝基复合材料.使用扫描电子显微镜,X射线衍射仪和傅里叶变换红外光谱仪等对石墨烯增强铝基复合材料的显微组织和力学性能进行研究.实验结果表明:石墨烯均匀的分散在复合材料中,相比于纯铝,石墨烯的质量分数仅为0.5%时,石墨烯增强铝基复合材料的维氏硬度和抗拉强度分别提高了19.7%和20%.     

西安市降尘中粉煤灰的岩石地球化学特征

利用X荧光光谱、化学分析、XRD、激光粒度分析和扫描电镜等方法,对西安不同城市功能区降尘样品中粉煤灰进行分析.结果表明,西安市降尘中粉煤灰颗粒主要为玻璃质物质,具有包裹结构和多孔性特征,降尘中粉煤灰平均含量24.99%,空间分布受电厂排灰控制.降尘中粉煤灰粒度小于10μm,平均粒径仅4.13μm,均属于可吸入颗粒,含有大量亚微米粒子,对人的呼吸系统危害极大.粉煤灰本身重金属含量较降尘低,说明城区的汽车和其它工业污染是更为重要的大气重金属污染源,粉煤灰本身带来的重金属元素在大气粉尘中不占主导地位.     

粉煤灰对高强混凝土性能的影响

在泵送混凝土中掺入适量的粉煤灰,特别是与减水剂复合使用时,不仅经济效益显著,而且能改善混凝土的性能.研究了粉煤灰高强混凝土中粉煤灰的细度、掺量对混凝土流动性、可泵性及强度的影响,最后给出了煤灰在高强混凝土中的最优掺量,可为工程应用借鉴.     

增钙灰的粉煤灰效应分析

本文从定性、定量两方面分析了增钙灰的“粉煤灰效应”．研究表明,品质好的增钙灰具有明显的“粉煤灰效应”,可用做掺合料配制较高强度的混凝土,“粉煤灰效应”包含形态效应、活性效应、微集料效应三方面的综合作周,定量分析便于把握材料的性质,指导材料的应用。     

空心陶瓷/AZ91D复合材料组织的研究

通过搅熔铸造法制备了平均粒径为100μm,质量分数为6%空心陶瓷增强镁合金复合材料（AZ91D/FAC）.研究不同质量分数的空心陶瓷对复合材料的组织的影响,利用XRD分析了AZ91D/FAC复合材料的物相,界面形貌及成分由配置能谱分析（EDS）的扫描电镜（SEM）来确定.结果表明,空心陶瓷增强AZ91D镁合金复合材料的布氏硬度比基体有较大的提高.通过O-lympus对组织的观察发现基体引入空心陶瓷后,组织细化,AZ91D镁合金铸态网状Mg17Al12消失.根据EDS分析及热力学计算,可知基体内有Mg2Si生成,界面产物为MgAl2O4.     

利用高钙粉煤灰生产粉煤灰水泥的试验研究

研究了高钙粉煤灰水泥的细度及活性激发剂对其物理性能的影响。研究结果表明,高钙粉煤灰水泥的安定性和各龄期的抗折、抗压强度均随着水泥的细度的提高和活性激发剂的掺入而提高,活性激发剂具有加速水泥矿物和ｆ Ｃａ Ｏ 水化的作用。采用５２５＃ 熟料,掺加３０％ 的高钙粉煤灰时,水泥的比表面积在３４０～４００ ｍ ２ ／ｋｇ 和掺入１％ 的活性激发剂,能够稳定生产４２５＃ 高钙粉煤灰水泥。     

Electromagnetic Interference Shielding Properties of Electroless Nickel-coated Carbon Fiber Paper Reinforced Epoxy Composites

Carbon fibers(CFs) were coated with a nickel-phosphorus(Ni-P) film using an electroless plating process. The morphology, elemental composition and phases in the coating layer of the CFs were investigated by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD), respectively. Wet paper-making method was used to prepare nickle coated carbon fiber paper(NCFP). Vacuum assisted infusion molding process(VAIMP) was employed to manufacture the NCFP reinforced epoxy composites, and carbon fiber paper(CFP) reinforced epoxy composites were also produced as a comparison. Electromagnetic interference(EMI) shielding properties of the composites were measured in the 3.22-4.9 GHz frequency range using waveguide method. Both NCFP and CFP reinforced epoxy composites of 0.5 mm thickness exhibited high EMI shielding effectiveness(SE) at 8wt% fiber content, 35 d B and 30 d B, respectively, and reflection was the dominant shielding mechanism.     

粉煤灰掺量对水工混凝土力学性能的影响

通过粉煤灰混凝土基本力学性能试验,分析了粉煤灰掺量、水灰比、龄期等因素对水工混凝土抗压强度、劈拉强度和抗压弹模的影响,探讨了粉煤灰对混凝土力学性能的影响机理.试验结果表明,随着粉煤灰掺量的增加,混凝土的早期强度有所降低,后期强度有明显提高.     

Synthesis and Electric Properties of Polyethylene Grlycol-modified Fly Ash Floating Bead/polyaniline Composites

Fly ash floating bead(FAFB) was modified by the nonionic surfactant polyethylene glycol(PEG) under various concentrations to improve its hydrophobility,and then PEG modified FAFB composited with polyaniline(FAFB-PEG/PAn) by emulsion polymerization method using different feed ratios of FAFBPEG.The chemical structure,phase structure,microstructure,conductivity,and dielectric properties were studied by FT-IR,XRD,SEM,four-probe technique,and LCR digital bridge,respectively.It was demonstrated that the optimal concentration of PEG was 1 mol/L and the corresponding grafting ratio was 1.42%.The phase structure of FAFB was not destroyed after modification by PEG,while the surface became smoother and could be coated by PAn successfully according to SEM technique.Compared to that of dodecylbenzenesulfonic acid doped PAn(PAn-DBSA),the conductivity of FAFB-PEG/PAn was decreased by 10-100 times after introduction of various amounts of FAFB-PEG,especially the value could be decreased to 0.01 S cm~(-1) if 50 wt%of FAFBPEG was provided.Additionally,the dielectric constant and loss factor of FAFB-PEG/PAn composites gradually decreased with increasing amount of FAFB-PEG in the frequency range of 100 KHz-2 MHz,namely,the dielectric constant could be still kept at 500 and correspondingly the loss factor decreased to 4.7 at 100 KHz if50 wt%of FAFB-PEG was provided.The leaking current phenomenon derived from PAn-DBSA could also be weakened by FAFB-PEG.