Core-shell-type Fe3O4@carbon nanoparticles and their fabrication using silanic/polymeric amino functionalization

A facile strategy for the fabrication of a carbon shell on Fe₃O₄ nanoparticles with a cluster structure has been proposed. Unlike the conventional solvothermal process using an autoclave, the proposed synthesis method could yield core-shell structured Fe₃O₄@C nanoparticles at low temperature and atmospheric pressure. This synthesis method was based on the chemical bonding among the terminal amine groups, introduced on the Fe₃O₄ surface, and carbonization by the catalytic reaction of glucose (carbon source) with sulfuric acid. The properties of the Fe₃O₄@C nanoparticles so obtained depended on the terminal amine groups that modified the iron oxide surface. The effects of the silane- and polymer-based amination on the fabrication of the carbon shell were investigated.     

Tailoring electromagnetic absorption performances of TiO2/Co/carbon nanofibers through tuning graphitization degrees

Low density, high stability and strong dielectric loss capacity endow carbon-based nanocomposites with superb microwave dissipation performances. Different from grapheme or carbon nanotubes, the graphitization degrees of carbon-based composites derived from the organic precursor pyrolysis can be accurately regulated by controlling the carbonization temperature. As such, their electromagnetic properties can be easily tuned. In this work, we report the preparation of TiO₂/Co/Carbon nanofibers (CNFs) through a combined approach of electrospun and carbonization at different temperatures. The nanofibers with an average diameter of 300 nm were coated by a dense layer of TiO₂ and embedded by Co/CoO nanoparticles. The performance evaluation indicated the composite obtained at 700 °C exhibits remarkably strong absorption of −63.2 dB at 9.8 GHz and wide effective absorption bandwidth of 6.4 GHz with a pretty low filling rate of 15 wt%. Further analysis on the electromagnetic behaviors shows that the composite possesses regulable impedance matching characteristic and absorption performances, implying the huge application potential under various demand conditions.     

杜拉纤维对钢筋混凝土抗压强度、碳化及钢筋腐蚀影响的实验研究

鉴于过去杜拉纤维对钢筋混凝土中钢筋腐蚀影响研究较少的现状,从杜拉纤维对钢筋混凝土的抗压强度、碳化等方面的影响进行了研究,同时用电化学的方法对加入杜拉纤维对钢筋腐蚀影响进行了探讨。结果表明:a)加入杜拉纤维对混凝土试块抗压强度提高不明显,而对钢筋腐蚀有一定的抑制作用,随杜拉纤维掺量增加,钢筋腐蚀电位增加;b)随杜拉纤维掺量增加,钢筋混凝土表面碳化深度减小。     

掺高钙粉煤灰混凝土的强度与耐久性试验

研究了不同粉煤灰掺量的高钙粉煤灰混凝土的抗压强度、抗碳化及抗氯离子渗透性能.结果表明,随着Ⅱ级高钙粉煤灰掺量的增加,28d的抗压强度相比于基准混凝土要低,60d和90d抗压强度则可达到甚至超过基准混凝土.而掺Ⅲ级高钙粉煤灰混凝土28d后的强度增长则不显著;掺Ⅱ级高钙粉煤灰的混凝土均比同龄期基准混凝土的碳化深度小,而掺Ⅲ级高钙粉煤灰时混凝土的碳化深度略大.试验还表明,掺Ⅱ、Ⅲ级高钙粉煤灰混凝土的抗氯离子渗透能力均比基准混凝土好.     

无粘结预应力混凝土结构耐久性研究

对无粘结预应力混凝土结构的耐久性进行了研究 ,分析了混凝土的碳化、无粘结预应力筋防腐润滑油脂的耐久性能和无粘结预应力锚固体系抗腐蚀的性能 ,提出了提高无粘结预应力混凝土结构耐久性的有效途径。     

连二硫酸锰碳化干渣热解回收硫酸钠的研究

利用软锰矿进行湿法冶金或烟气脱硫技术研究时,因其即可控制大气污染亦可回收锰资源而备受关注。然而,反应过程会生成影响脱硫尾液中硫酸锰的品质的副产物—连二硫酸锰（杂质）,如何回收或去除该杂质是技术研发和推广的难题。本文提出了连二硫酸锰先经碳酸氢钠碳化得到连二硫酸钠和碳酸锰,两产物分离后,结合低温热解的方法将连二硫酸钠制备成无水硫酸钠;实验考察了热解制备过程的各产物和控制反应步骤的温度,进而推理出动力学参数和反应机理。热解实验结果表明：255 ℃（摄氏度）是连二硫酸钠热解制备无水硫酸钠的最佳热解反应温度,并且热解反应过程经历脱硫和脱水两大步骤;热解产物的X射线衍射（XRD）和离子色谱（IC）表征结果表明：产物为单一相的立方体结构硫酸钠晶体。利用热重示差扫描热分析（TG-DSC）对连二硫酸钠热解过程进行表征,结合Kissinger微分法和Coats-Redfern积分法对热解法中脱水和脱硫过程中的活化能进行推算,脱水和脱硫活化能分别在14.75-18.11 kJ/mol（千焦/摩尔）和132.61-137.18 kJ/mol范围内。热解尾气测定结果表明：连二硫酸钠热解制备无水硫酸钠时释放出的尾气主要为二氧化硫。因此,经低温热解工艺处理软锰矿脱硫尾液中连二硫酸根的方法是可行的,不仅可以避免液相处理工艺中酸性废水产生的问题,还可以利用热解制备过程中的尾气去除残留的碳化剂（碳酸钠）,以达到资源化回收目的。     

纳米级炭黑在不同热处理温度下的结构研究

在惰性气氛保护下,对炭黑样品进行不同温度下的热处理,得到具有不同石墨化度的炭黑样品。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、热重分析仪(TG)、以及拉曼分析仪(Raman)等对其进行了结构表征,结果表明随着碳化温度的升高,炭黑样品的石墨化程度显著增大,尤其在经过2 800℃高温热处理的炭黑样品中出现了中空的石墨化结构,有望成为具有较大吸附性能的橡塑弹性体材料的较好补强剂。     

Critical assessment of thermodynamic properties of important polycyclic aromatic hydrocarbon compounds (PAHs) in coal tar pitch at typical temperature ranges of the carbonization process

Because of the importance of thermodynamic behavior of Polycyclic Aromatic Hydrocarbon (PAH) compounds in coal tar pitch carbonization process, a thermodynamic model for the prediction of thermodynamic properties of PAH compounds is developed. Heat capacity functions as well as standard thermodynamic properties of PAHs in solid, liquid, and gas states are estimated using modified group additivity algorithms first proposed by Richard and Helgeson and thermal physical data of those PAHs for which enough experimental data exists in the literature. For the first time, initial calculated thermodynamic properties of PAHs are optimized by applying the CALPHAD (CaLculation of PHAse Diagrams) approach where all thermodynamic data are rendered consistent with phase transitions and vapor pressure data. The heat capacity function of PAHs exhibiting thermal anomaly behavior is modeled as a specific case. This modeling is performed using an order-disorder approach with the Compound Energy Formalism (CEF). Good agreement has been obtained between the predicted thermodynamic properties of PAHs and available experimental data. The proposed model has improved the predictive capacity compared to that of the previous models predicting thermodynamic properties of PAHs at typical temperature ranges of the carbonization process. The application of the model to predict the thermodynamic properties of major and high molecular weight PAHs available in coal tar pitch has been discussed.     

Small Carbon Forms From Polyaniline/Metal

Polymerization of the aniline with camphorsulfonic acid in the presence of PdCl₂, (PhCN)₂PtCl₂ (Ph = phenyl), or ZnO nano-particles was carried out to prepare metal-containing polyaniline. The surface structures were observed with SEM. Carbonization of the metal-containing PANI provided nano-structured carbons. Electron probe microanalyzer spectroscopy measurements evaluated the presence of metal atoms in the carbons.     

钢渣制品的最佳碳化制度

通过对钢渣制品进行碳化养护,确定其最佳的碳化制度.实验结果表明:当液态外加剂掺入量为9.00%,初始成型压力f为3.0 MPa时,钢渣制品在CO2分压为fco2=0.25 MPa、fco2=0.55 MPa和fco2=0.75 MPa的压强下各碳化养护1 h后,其碳化增重率迭11.02%,在最佳的碳化制度下,相对于未碳...