Na_(2)CO_(3)·10H_(2)O-Na_(2)HPO_(4)·12H_(2)O/SiO_(2)复合定形相变材料的制备及应用

以Na_(2)CO_(3)·10H_(2)O(SCD)、Na_(2)HPO_(4)·12H_(2)O(DHPD)为相变主体制备了共晶体系,通过绘制凝固点变化图与DSC测试共同确定在m(SCD)∶m(DHPD)=4∶6时形成共晶,FTIR和XRD结果显示,2种水合盐间没有发生化学反应,但其晶型结构发生改变。通过添加质量分数为2%的Na2SiO3·9H_(2)O作为成核剂降低体系的过冷度,且经历50次相变循环体系未出现相分离,相变焓值仅下降0.25%。进一步使用质量分数为25%的气相SiO_(2)作为支撑材料,采用浸渍法制备了相变前后形状稳定的共晶水合盐/SiO_(2)定形相变材料(SSPCM)。所得SSPCM的相变温度为24.08℃,相变焓值为146.6J/g,过冷度为0.55℃,热导率为0.4571W/(m·K)。同保温泡沫相比,其可将模拟房内部中心温度的升温时间延长了1.81倍,降温时间延长了0.39倍。

Ag_(3)PO_(4)/Cu_(2)O复合材料的制备及其性能研究

对磷酸银复合材料制备及光催化性能进行了研究。讨论了水热温度、反应溶液的酸碱度等对Cu_(2)O制备的影响。同时,比较了不同摩尔百分比Ag_(3)PO_(4)含量的Ag_(3)PO_(4)/Cu_(2)O复合材料的光催化降解活性。结果显示,球状Cu_(2)O颗粒制备条件为:温度100℃,pH值为10。采用直接沉淀法Ag_(3)PO_(4)纳米颗粒能够均匀附着Cu_(2)O表面,达到最佳复合效果。Ag_(3)PO_(4)/Cu_(2)O复合材料光催化活性高于纯Cu_(2)O,随着Ag_(3)PO_(4)的摩尔百分量的增加,复合光催化剂的催化性能先是增强后逐渐减弱。60%Ag_(3)PO_(4)/Cu_(2)O时,催化活性最强,90 min内罗丹明B几乎完全降解。

Synthesis of Y_2O_3 particle enhanced Ni/TiC composite on TC4 Ti alloy by laser cladding

A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer were investigated. The composite layer has graded microstructures and compositions, due to the fast melting followed by rapid solidification and cooling during laser cladding. The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified. The size of TiC dendrites decreases with increasing depth. Y2O3 fine particles distribute in the whole clad layer. The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380, which is 4 times higher than the initial hardness. The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.

Morphology and Frictional Characteristics Under Electrical Currents of Al_2O_3/Cu Composites Prepared by Internal Oxidation

Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and copper against brass are investigated and compared. The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope （SEM） and energy dispersive X-ray spectrum （EDS）. The results show that the wear resistance of the Al2O3/Cu composites is superior to that of copper under the same conditions, Under a given electrical current, the wear rate of Al2O3/Cu composites decreases as the Al2O3-content increases, However, the wear rates of the Al2O3/Cu composites and copper increase as the sliding speed and pressure increase under dry sliding condition. The main wear mechanisms for Al2O3/Cu composites are of abrasion and adhesion; for copper, it is adhesion, although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.

Effect of La_2O_3/Ce O_2 particle size on high-temperature oxidation resistance of electrodeposited Ni-La_2O_3/Ce O_2 composites

Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.

Preparation of Al_2O_3/Au nano-laminated composite coatings and their oxidation resistance on stainless steel

Al2O3/Au nano-laminated composite coatings were prepared by means of magnetron sputtering. The coating was compact and comprised of nano-laminated Al2O3 and Au layers. High temperature cyclic oxidation test was employed to investigate the oxidation resistance of the composite coatings. The results revealed that the applied Al2O3/Au nano-laminated composite coatings improved the oxidation and spallation resistance of the stainless steel substrate significantly. The mechanism accounting for oxidation resistance was related with the suppression of inward oxygen diffusion and selective oxidation of Cr in the substrate. The mechanism accounting for spallation resistance was attributed to the relaxation of thermal stress by the nano-laminated structure.

A Decisive Study on Dielectric Response of Bi2O3/Polystyrene &Bi2O3/PVDF Composite as Flexible Electrodes for Energy Storage

In this manuscript a comparative study on Bi2O3/polystyrene and Bi2O3/PVDF composites has been executed via analysis of structural, bonding, surface morphology and dielectric response of composites for energy storage. The composites have been synthesized using solution cast method by varying concentrations of Bi2O3 (BO = 1 - 5 mw%) into polystyrene (PS) and polyvinylidene fluoride (PVDF) polymers respectively. X-ray diffraction confirms the generation of crystallinity, Fourier transform infrared (FT-IR) spectroscopy confirms bonding behavior and scanning electron microscopy (SEM) confirms uniform distribution of Bi2O3 (BO) in PS and PVDF polymers. Impedance spectroscopy has been employed for determination of dielectric response of the fabricated composites. The dielectric constant has been found to be increased as 1.4 times of pristine PS to BO5%PS95% composites and 1.8 times of pristine PVDF to BO5%PVDF95% composites respectively. These high dielectric composite electrodes are useful for flexible energy storage devices.

Kinetics and Mechanism of Oxidation Induced Contraction of MgAl2O4 Spinel Carbon Composites Reinforced by Al4C3 in situ Reaction

Kinetics and mechanism of oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced by Al4C3 in situ reaction were researched in air using vertical high temperature thermal dilatometer from 25℃to 1400℃.It is shown that oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced Al4C3 in situ reaction is the common logarithm of oxidation time t and the oxygen partial pressure P inside MgAl2O4 spinel carbon composites reinforced by Al4C3 in situ reaction in air at 1400℃is as follows:P=F(-2.75×10^-4A+2.13×10^-3)lnt.The nonsteady diffusion kinetic equation of O2 at 1400℃inside the composites is as follows:J=De lnt.Acceleration of the total diffusional?flux of oxygen inside the composites at 1400℃is in inverse proportion to the oxidation time.The nonsteady state effective diffusion coefficient De of O2(g)inside the composites decreases in direct proportional to the increase of the amount of metallic aluminium.The method of preventing the oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced by Al4C3 in situ reaction is to increase the amount of Al.The slag erosion index of MgO-Al2O3 spinel carbon composite reinforced by Al4C3 in situ reaction is 0.47 times that of MgO-CaO brick used in the lining above slag line area of a VOD stainless steel-making vessel.HMOR of MgO-Al2O3 spinel carbon composite reinforced by Al4C3 in situ reaction is 26.7 MPa,HMOR of the composite is 3.6 times the same as that of MgO-CaO brick used in the lining above slag line area of a VOD vessel.Its service life is two times as many as that of MgO-CaO brick.

Preparation,characterization and catalytic behavior of hierachically porous CuO/α-Fe_2O_3/SiO_2 composite material for CO and o-DCB oxidation

Hierachically porous （HP） CuO/α-Fe2O3/SiO2 composite material was fabricated by sol-gel method and multi-hydrothermal processes using HP-SiO2 as support.The resulting material was characterized by N2 adsorption-desorption,X-ray diffraction and scanning electron microscopy.The as-prepared CuO/Fe2O3/HP-SiO2 sample,with α-Fe2O3 and CuO nanocrystals,possessed a co-continuous skeleton,through-macroporous and mesoporous structure.Its catalytic behavior for CO and o-DCB oxidation was investigated.The result showed that CuO/Fe2O3/HP-SiO2 catalyst exhibited high catalytic activity for both CO and o-DCB oxidation,indicating its potential application in combined abatement of CO and chlorinated volatile organic compounds.

Rh_2O_3/monoclinic CePO_4 composite catalysts for N_2O decomposition and CO oxidation

CePO4 （in particular, monoclinic CePO4） has been rarely used to make supported catalysts. Herein, monoclinic CeP04 nanoparticles were prepared by calcining hexagonal CePO4 nanomds （prepared by precipitation） in air at 900 ℃. Monoclinic CePO4 nanowires were prepared by calcining hexagonal CePO4 nanowires （prepared by hydrothermal synthesis at 150 ℃） in air at 900 ℃. Both monoclinic CePO4 materials were used to support Rh2O3 by impregnation using Rh（NO3）3 as a precursor （followed by calcination）. The catalytic performance of Rh2O3/monoclinic CePO4 composite materials in N2O decomposition and CO oxidation was investigated. It was found that Rh2O3 supported on monoclinic CePO4 nanowims was much more active than Rh2O3 supported on monoclinic CePO4 nanoparticles. The stability of catalysts as a function of reaction time on stream was studied in both reactions. The influence of co-fed CO2, O2, and H2O on the catalytic activity in N20 decomposition was also studied. These catalysts were characterized by employing N2 adsorption-desorption, ICP-OES, XRD, TEM, XPS, H2-TPR, O2-TPD, and CO2-TPD. The correlation between physicochemical properties and catalytic properties was discussed.

Si_3N_4-Fe对Al_2O_3-SiC-C质铁沟浇注料性能的影响

利用Si3N4 的优良性质及金属塑性相Fe的作用 ,将其添加到高炉出铁沟用Al2 O3-SiC -C浇注料中 ,以改善材料的力学性能和抗氧化性能。对高温处理后试样强度、显气孔率测试以及对氧化层的SEM分析 ,结果表明 ,添加适量的Si3N4 -Fe ,材料的显气孔率降低 ,强度提高 ,抗氧化性增强。

Heterogeneous catalytic activation of peroxymonosulfate for efficient degradation of organic pollutants by magnetic Cu^0/Fe_3O_4 submicron composites

Magnetic Cu^0/Fe3O4 submicron composites were prepared using a hydrothermal method and used as heterogeneous catalysts for the activation of peroxymonosulfate（PMS） and the degradation of organic pollutants.The as-prepared magnetic Cu^0/Fe3O4 submicron composites were composed of Cu^0 and Fe3O4 crystals and had an average size of approximately 220 nm.The Cu^0/Fe3O4 composites could efficiently catalyze the activation of PMS to generate singlet oxygen,and thus induced the rapid degradation of rhodamine B,methylene blue,orange Ⅱ,phenol and 4-chlorophenol.The use of0.1 g/L of the Cu^0/Fe3O4 composites induced the complete removal of rhodamine B（20 μmol/L） in15 min,methylene blue（20 μmol/L） in 5 min,orange Ⅱ（20 μmol/L） in 10 min,phenol（0.1mmol/L） in 30 min and 4-chlorophenol（0.1 mmol/L） in 15 min with an initial pH value of 7.0 and a PMS concentration of 0.5 mmol/L.The total organic carbon（TOC） removal higher than 85%for all of these five pollutants was obtained in 30 min when the PMS concentration was 2.5 mmol/L.The rate of degradation was considerably higher than that obtained with Cu^0 or Fe3O4 particles alone.The enhanced catalytic activity of the Cu^0/Fe3O4 composites in the activation of PMS was attributed to the synergistic effect of the Cu^0 and Fe3O4 crystals in the composites.Singlet oxygen was identified as the primary reactive oxygen species responsible for pollutant degradation by electron spin resonance and radical quenching experiments.A possible mechanism for the activation of PMS by Cu^0/Fe3O4 composites is proposed as electron transfer from the organic pollutants to PMS induces the activation of PMS to generate ^1O2,which induces the degradation of the organic pollutants.As a magnetic catalyst,the Cu^0/Fe3O4 composites were easily recovered by magnetic separation,and exhibited excellent stability over five successive degradation cycles.The present study provides a facile and green heterogeneous catalysis method for the oxidative removal of organic pollutants.

纳米Al_2O_3-Fe_3O_4/FeS固体润滑复合层减摩润滑机理

采用离子氮碳共渗与离子渗硫复合处理技术在45钢表面形成FeS固体润滑复合层,然后采用真空浸渍方法将纳米Al2O3和Fe3O4颗粒置入复合层的微纳孔隙中,制备成纳米Al2O3-Fe3O4/FeS固体润滑复合层。在10～60 N的载荷下,纳米Al2O3-Fe3O4/FeS固体润滑复合层表现出优良的减摩与耐磨性能。这是因为,一方面磨损表面生成的化学反应膜,起到了固体润滑和阻碍摩擦表面间金属直接接触的作用;另一方面在摩擦过程中,纳米Al2O3-Fe3O4/FeS固体润滑复合层中的纳米Al2O3和Fe3O4颗粒起到了'微纳滚珠'作用,微观上将'滑动摩擦'部分转变为'滚动摩擦',且纳米颗粒预先置入复合膜层中,在摩擦过程中不易流失,延长了其'微纳滚珠'的作用,从而使其摩擦因数(载荷60 N时)及体积磨损量比涂抹纳米Al2O3/Fe3O4复合添加剂润滑的FeS固体润滑复合层分别降低了7.2%和50%。

桉树遗态Fe_2O_3-Fe_3O_4/C复合材料的制备及其对水中锑(Ⅲ)的吸附研究

以桉树为植物模板,通过氨水浸提、硝酸铁浸渍和马弗炉有氧焙烧等处理制备获取桉树遗态Fe2O3-Fe3O4/C复合材料,借助扫描电镜和X射线衍射分析仪等手段对其进行了结构和性质分析;通过吸附试验研究了初始Sb(Ⅲ)含量、pH、吸附剂投加量以及吸附剂粒径对吸附效果的影响。结果表明,获取的复合材料很好地保留了桉树自身固有的植物本征结构,且Fe2O3和Fe3O4是其主要组成部分,呈现出其对水中Sb(Ⅲ)的良好吸附性能;随着Sb(Ⅲ)初始含量的增加,桉树遗态Fe2O3-Fe3O4/C复合材料对Sb(Ⅲ)的吸附量增大;温度对吸附除Sb(Ⅲ)没有明显影响;初始溶液pH为8时,Sb(Ⅲ)的去除效果最好;适宜吸附剂投加量为0.5 g/50 mL;吸附剂粒径小利于吸附率的提高,但块状材料也显示出良好的吸附性能。

微波催化剂MgFe_2O_4-Fe_2O_3微波催化氧化降解结晶紫废水

提出一种新型的、无需添加氧化剂处理结晶紫废水的方法.通过共沉淀晶化法制备微波催化剂MgFe_2O_4-Fe_2O_3,在微波辐照下降解结晶紫废水,考察了催化剂用量、微波功率、辐照时间对结晶紫去除率的影响.结果表明:在一定条件下,去除率随着催化剂用量的增加、微波功率的增大、微波辐照时间的延长而增加.当微波功率为800 W,辐照时间5min,催化剂用量1g/L时,处理200mg/L的结晶紫废水,去除率可达99.3%.本文还对微波催化氧化机理进行了探究,通过添加不同氧化基团清除剂的实验发现,氧化基团清除剂的添加降低了结晶紫的去除率,并提出了该反应的微观机理:微波催化剂吸收电磁波发生光电效应,产生电子和空穴对,与水等作用产生·OH,·OH再氧化降解废水中的有机物.

Co_(3)O_(4)/CeO_(2)催化剂上丙烷完全氧化反应中载体性质影响

采用不同制备方法合成不同性质的CeO_(2)载体,并制备负载型Co_(3)O_(4)/CeO_(2)催化剂应用于丙烷完全氧化反应。结果表明,部分CO_(2)+进入CeO_(2)晶格中形成固溶体,改变了CeO_(2)的晶格结构并产生氧空位。氧空位的数量与不同性质的CeO_(2)密切相关,影响催化剂上氧物种的可还原性,从而对反应行为产生影响。其中,以沉淀法制备的CeO_(2)为载体的5Co/CeO_(2)-C催化剂活性最佳(T_(90)=320℃),可归因于该催化剂中较高氧空位浓度导致的最佳低温可还原性。此外,该催化剂还具有良好的稳定性和抗水性能。

磁性Fe_3O_4/α-Fe_2O_3核壳材料降解水中亚甲基蓝

以Fe_3O_4为核,以α-Fe_2O_3为壳层,合成出一种核壳结构的Fe_3O_4/α-Fe_2O_3纳米复合材料.采用扫描电镜（SEM）、透射电镜（TEM）和X-射线衍射仪（XRD）等表征手段对核壳材料的形貌、组成及结构等进行了表征,并将其应用于亚甲基蓝溶液的降解.结果表明：核壳结构的Fe_3O_4/α-Fe_2O_3纳米粒子粒径约为50-80nm.当H_2O_2用量为0.23mol/L,Fe_3O_4/α-Fe_2O_3投加量为5g/L,pH值为2,亚甲基蓝溶液初始质量浓度为5.0mg/L,60min内亚甲基蓝的降解可达98.7%.Fe_3O_4/α-Fe_2O_3纳米粒子经过3次循环使用后,对亚甲基蓝仍具有较好的降解能力.

α-Fe_2O_3/Fe_3O_4复合负极材料的制备与电化学性能研究

通过固相反应法合成出α-Fe2O3/Fe3O4复合产物,利用XRD、Raman、SEM等技术和恒电流充放电方法,探讨了恒温反应时间对材料微观结构、形貌以及电化学性能的影响。研究表明,恒温反应时间对复合产物中各组分的相对含量、形貌与电化学性能影响较大;除首次循环外,复合负极材料在随后充放电过程中库伦效率可达96%以上,循环性能与倍率性能明显优于单相α-Fe2O3负极材料与Fe3O4负极材料。

磁性Fe_3O_4/α-Fe_2O_3核壳材料的制备及处理含铬(Ⅲ)废水的应用

以Fe3O4为核、α-Fe2O3为壳层,制备出1种核壳结构的Fe3O4/α-Fe2O3负载型纳米复合材料,采用扫描电子显微镜（SEM）、透射电镜（TEM）和X射线衍射仪（XRD）等表征手段对核壳材料的形貌、组成及结构等进行了表征,并考察了该材料对Cr（Ⅲ）的去除性能以及Fe3O4/α-Fe2O3粒子的再生和重复利用性能。结果表明,制备得到的Fe3O4/α-Fe2O3纳米粒子具有典型的核壳结构,粒径约为40~100 nm。在p H为4.5时,Fe3O4/α-Fe2O3对Cr（Ⅲ）的饱和吸附量达到33.34 mg/g。Freundlich方程比Langmuir方程更好地描述了Fe3O4/α-Fe2O3吸附Cr（Ⅲ）的行为,表明此吸附是多层物理吸附。以0.1 mol/L的H2SO4为解吸剂将吸附在核壳Fe3O4/α-Fe2O3上的Cr（Ⅲ）解吸,可以实现很好的再生,再生的Fe3O4/α-Fe2O3经过3次循环使用后,对Cr（Ⅲ）仍具有较好的去除能力。

以固体超强酸SO_4^(2-)/ZrO_2-Fe_2O_3催化合成醋酸异戊酯

以合成醋酸异戊酯为探针反应,筛选出制备固体超强酸SO2-4 /ZrO2- Fe2O3 (SZF -1 )的最佳工艺条件为:ZrOCl2·8H2O9. 7g, FeCl3·6H2O16. 2g, 常温陈化24h, 0. 5mol·L-1 H2SO4 (15mL·g-1 )浸泡5h, 550℃焙烧3h。以SZF 1为催化剂合成醋酸异戊酯的反应条件为:异戊醇200mmol, n(异戊醇)∶n(醋酸) =1. 0∶1. 3, SZF -1 1g(反应物总质量的3% ), 环己烷15mL, 回流反应3h, 酯化率93. 47%。催化剂连续使用6次后酯化率仍在70%以上。