Na_2O含量对包钢稀选尾矿制备微晶玻璃析晶行为和性能的影响

采用DSC、XRD、SEM等方法研究了Na2O含量对以包钢稀选尾矿为主料制备微晶玻璃析晶行为及性能的影响。结果表明:随着Na2O含量的增加,微晶玻璃的晶化温度逐渐降低;当Na2O质量分数大于6.7%时,主晶相由钙铁辉石变为霞石;当Na2O质量分数为3.6%时,微晶玻璃的抗弯强度最大为150.4 MPa,密度最大为3.4 g.cm-3。     

利用废料直接烧结制备CaO-Al2O3-SiO2微晶玻璃及其性能

以废玻璃、粉煤灰和氧化钙为原料,采用直接烧结法制备了CaO-Al2O3-SiO2(CAS)微晶玻璃;研究了CaO加入量和烧结温度对微晶玻璃烧结性能、晶相组成、显微结构和抗弯强度的影响。结果表明:随着CaO加入量的增多以及烧结温度的升高,微晶玻璃的体积密度先增大后减小;高的CaO加入量和烧结温度促进了柱状硅灰石晶相的生成;CAS微晶玻璃抗弯强度与体积密度的变化趋势基本相同;加入CaO质量分数为18%、在1 100℃烧结2h制备的CAS微晶玻璃的体积密度最大,为2.26g.cm-3,其主晶相为单一β-硅灰石,结晶度为50.7%,抗弯强度最大,为81.5MPa。     

水热合成大长径比的γ-AlOOH纳米线及表征

以NaOH和NH3·H2O的混合溶液为沉淀剂,在水热条件下制备了大长径比的γ-AlOOH纳米线;并采用X射线衍射仪和透射电子显微镜对制备的产物进行了表征。结果表明:调节混合沉淀剂中NaOH和NH3·H2O的比例,可得到不同形貌的γ-AlOOH纳米结构;大长径比γ-AlOOH纳米线是由水热反应初期形成的尺寸较大的层状γ-AlOOH通过卷曲而形成的;以体积比1∶1的NaOH和NH3·H2O混合溶液为沉淀剂,在保温时间24h条件下,制备的γ-AlOOH纳米线形态最好,其直径为10~30nm,长度为1~2μm,长径比为60~100,并具有明显的晶面择优取向。     

直接敷铜工艺制备Cu/AlN材料的界面结构及结合性能

通过直接敷铜(DBC)工艺,在AlN陶瓷基板表面于1 000~1 060℃的敷接温度下制备Cu/AlN材料,利用机械剥离机、场发射扫描电子显微镜和X射线衍射仪分析了Cu/AlN的界面结合强度、界面微观形貌和物相组成。结果表明:铜箔和AlN陶瓷基板间的结合强度超过了8.00N·mm~(-1),铜箔和AlN陶瓷之间存在厚度约为2μm的过渡层,过渡层中主要含有Al_2O_3、CuAlO_2和Cu_2O化合物;随着敷接温度升高,Cu/AlN的界面结合强度逐渐增大。     

强迫水解化学还原法制备纳米Cu2O及其光催化性能

以Cu(CH3COO)2.2H2O为铜源,水和乙二醇的混合溶液为溶剂,在回流条件下通过强迫水解化学还原法制备了纳米Cu2O,对影响其结晶程度和晶粒大小的因素进行了分析,并测试了其光催化性能。结果表明:水和乙二醇体积比、回流反应时间和Cu(CH3COO)2初始浓度对产物Cu2O的结晶程度和晶粒大小有着重要的影响;制备的Cu2O在可见光下照射210min后甲基橙的降解率达到89%,其光催化活性优于市售P25TiO2的。     

尖晶石型CuAl_2O_4的制备及可见光催化性能

分别以硝酸铜、氯化铜、硫酸铜为原料,通过溶胶-凝胶法制备尖晶石型CuAl_2O_4粉体,采用X射线衍射仪、光催化反应器、红外光谱仪、X射线光电子能谱仪等研究了粉体的物相组成、光催化性能和微观结构。结果表明:以硫酸铜为原料,在焙烧温度为700℃,氨水体积20mL条件下合成的CuAl_2O_4粉体的光催化性能最佳,对甲基橙的降解率达到90%;以硫酸铜为原料制备的CuAl_2O_4粉体中存在Cu_2O(SO_4)相,提高了CuAl_2O_4粉体的光催化性能。     

Al2O3 陶瓷墨水的乳化分散制备工艺

以纳米α-Al2O3为原料,用乳化分散法制备Al2O3陶瓷墨水,探讨了制备工艺条件对墨水理化性能的影响.结果表明,以异丙醇/乙醇二元混合溶液为溶剂,通过选择分散剂品种、控制分散剂用量、乳化剪切转速、分散时间、固相含量等条件,可制备出分散稳定性良好的Al2O3陶瓷墨水.打印实验证明乳化分散法制备的Al2O3陶瓷墨水能够满足喷墨打印的要求.     

加热温度对烧结制备Li2O-Al2O3-SiO2系玻璃陶瓷显微结构的影响

以Li2O-Al2O3-SiO2(LAS)系为基础玻璃成分,以碳酸锂、二氧化硅、氧化铝等为原料,采用烧结法制备了LAS系微晶玻璃.使用DTA分析了玻璃的析晶过程,运用XRD、SEM等测试分析手段对材料的晶相和晶粒大小进行了观察和分析,并讨论了加热温度对制品的烧结程度、主晶相及晶粒大小的影响.结果表明:当温度低于940℃时,所制微晶玻璃的主晶相为β-石英固溶体,高于940℃时主晶相转变为β-锂辉石;在1120℃时,烧结效果最好,在1170℃晶化效果最好,晶粒尺寸为0.5～3μm.     

Fe-Al_2O_3磁性磨料制备新工艺

分别以还原铁粉和雾化铁粉作为磁性粉,刚玉粉为磨粒,高温无机粘结剂为胶粘剂,并对铁粉进行表面改性后,采用烧结法制备了四种不同的Fe-Al2O3磁性磨料;采用X射线衍射仪和扫描电子显微镜分析了磁性磨料的物相组成和外观形貌,测试了磁性磨料的研磨性能,研究了铁粉种类以及表面改性处理对磁性磨料性能的影响。结果表明:制备的磁性磨料主要由-αFe、Al2O3、Fe2O3、AlFeO3(、Al,Fe)7BO3(SiO4)3O3等相组成,其形状多为不规则的棱状颗粒;制备的磁性磨料均具有良好的研磨效果和较长的耐用度,研磨工件的表面粗糙度可达到0.15μm,使用时间达到24 min;采用还原铁粉比用雾化铁粉、用表面改性的铁粉比用未改性的铁粉所制备磁性磨料的研磨性能要好。     

表面修饰硼酸镧纳米粒子的制备及摩擦学性能

以La(NO3)3.6H2O和Na2B4O7.10H2O为原料,添加硅烷偶联剂KH550,采用化学沉淀法制备出表面被修饰的硼酸镧纳米粒子;将制备的纳米颗粒按2%的比例加入纯基础油中制备成液固相分散体系,采用透射电子显微镜对体系的分散性进行表征,采用MMU-10G摩擦磨损试验机测试该分散体系对钢摩擦副的摩擦学性能。结果表明:该润滑油分散体系具有优异的抗磨性能以及良好的减摩效果,与纯基础油相比,在250 N、450 r/min转速下摩擦运行30 h的磨损率下降83%,摩擦因数下降30%。SEM、EDX分析表明,在摩擦过程中硼酸镧纳米材料参与了摩擦表面的成膜反应,起到了修复作用。     

空心玻璃微珠表面的CoFe_2O_4包覆及其微波吸收性能研究

采用共沉淀法在空心微珠表面上制备出由CoFe2O4铁氧体纳米颗粒均匀包覆层。利用X射线衍射仪(XRD)、能谱仪(EDX)和扫描电镜(SEM)对其进行分析表征,包覆层厚度为200nm。将这种复合材料均匀地分散于酚醛树脂粘合剂中,涂刷在面积为200mm×200mm金属板上,制成测试版,用RAM反射率远场RCS测量法对其进行微波吸收测试。测试结果表明,涂层对频率高于16GHz的微波有良好吸收,微波吸收性能好于CoFe2O4/A l2O3核壳结构纳米颗粒情况。     

Synthesis,characterization and tribological properties of Cu/reduced graphene oxide composites

In this paper, nano-copper/reduced graphene oxide (Cu/rGO) composites were synthesized by the facile one step in-situ reduction method. The as-prepared Cu/rGO composites were characterized by means of transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD) and Raman. Mechanism of reduction and growth of Cu/rGO composites were also discussed. The friction and wear properties of oleic acid (OA) modified composites as additives in poly-alpha-olefin (PAO) were investigated using four-ball wear tester.     

Versatile system for the temperature-controlled preparation of oxide crystal surfaces

We present a versatile system for the preparation of oxide crystal surfaces in the ultra-high vacuum (UHV) at temperatures up to 1300 K. Thermal treatment is accomplished by direct current heating of a tantalum foil in contact with the oxide sample. The sample temperature is measured by a thermocouple at a position close to the crystal and its reading is calibrated against the surface temperature determined by a second thermocouple temporarily attached to the surface. The design of the sample holder is based on a transferable plate originally developed for a commercial UHV scanning probe microscope. The system is, however, also suitable for the use with electron spectroscopy or electron diffraction based surface analytical techniques. We present results for the high-temperature preparation of CeO(2)(111) surfaces with atomically flat terraces exhibiting perfect atomic order and cleanliness as revealed by non-contact atomic force microscopy (NC-AFM) imaging. NC-AFM imaging is, furthermore, used to demonstrate the temperature-controlled aggregation of gold atoms on the CeO(2)(111) surface and their evaporation at high temperatures.     

TEM study of the structural dependence of the epitaxial passive oxide films on crystal facets in polyhedral nanoparticles of chromium

Nanocubes and partially truncated rhombic dodecahedral nanoparticles of Cr have been studied by electron diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. It is found that the nanoparticles of Cr are enclosed by the epitaxial passive oxide films. The oxide films on 100% truncated nanocubes of Cr with only one kind of facets, (100) facets, are face-centered cubic (fcc) structured Cr(2)O(3) with a lattice constant of 0.407nm. There are two kinds of oxide films in partially truncated nanoparticles of Cr with two kinds of crystallographic facets, (100) and (110). The same fcc Cr(2)O(3) is found on the (100) facets while the rhombohedral [Formula: see text] -Cr(2)O(3) is found on the (110) facets. This is similar to the two kinds of oxides, fcc and rhombohedral Fe(2)O(3), which have also been observed in polyhedral nanoparticles of Fe. These passive Cr(2)O(3), found in nanoparticles of Cr which have remained unchanged in water for four years, may have important implications for protective oxide films involving Cr.     

水热法制备板钛矿型TiO_2纳米颗粒及其表征

采用水热法成功合成板钛矿型TiO2纳米颗粒。利用X射线衍射仪、透射电子显微镜、拉曼光谱仪、激光粒度分析仪对样品进行分析表征,结果表明TiO2纳米颗粒为棒状,直径约为10nm,长度约为100nm。发现所合成的样品随着反应时间,其长度有明显的增加,而直径没有明显的变化。     

离子束增强沉积薄膜的摩擦磨损行为与结构分析

采用离子束增强沉积（IBED）技术在不锈钢1Cr18Ni9Ti衬底表面生长氮化钛薄膜以及氮离子注入,进行了干滑动摩擦磨损试验与组织结构电镜分析,表明增强沉积膜较离子注入具有更高耐磨性能。     

二步阳极氧化法制备氧化铝模板及机理分析

用预处理的铝箔,以草酸为电解液,采用二步阳极氧化法制备多孔有序阳极氧化铝阵列模板,利用透射电镜和X射线衍射仪对其进行表征,并对阵列孔的形成机理进行分析.结果表明:适当提高电压有利于孔的有序化;孔的有序化存在一个最佳阳极氧化时间,本试验条件下为6 h;根据试验结果并结合目前几个常见模型可较圆满解释阵列孔的形成过程.     

TiAlN／SiO2纳米多层刀具涂层的微观结构和超硬效应研究

通过磁控溅射方法制取了一系列不同SiO2厚度的TiAlN／SiO2纳米多层涂层,并用X射线衍射仪（XRD）、扫描电镜（SEM）、高分辨透射电镜（HRTEM）和纳米压痕仪分别对该涂层的微观结构和力学性能进行了表征和测量。研究表明：当非晶态的SiO2厚度约小于1nm时,SiO2在TiAlN模板作用下转变为晶体结构,并与TiAlN呈共格外延生长,出现超硬效应;当SiO2厚度为0．6nm时,其硬度和弹性模量分别高达37GPa和393GPa;当SiO2厚度超过lnm时,SiO2逐渐转变为非晶结构并且破坏了多层涂层的共格外延生长,硬度随之降低。因此,可以利用该方法制备出机械性能好且耐高温氧化性的刀具涂层,以满足现代切削的需要。     

Field emission studies on electrochemically synthesized ZnO nanowires

Nanocrystalline zinc oxide (ZnO) films were synthesized using cathodic reduction of Zn foil in aqueous electrolyte of different molar concentrations containing ZnCl₂ and H₂O₂, followed by annealing at 400 °C in air. An X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used for characterization. The XRD patterns exhibited a set of well-defined diffraction peaks corresponding to the wurtzite phase of ZnO. SEM and TEM images clearly revealed the formation of randomly oriented ZnO nanowires having lengths of several microns and diameters less than 100 nm. From the field emission studies, the threshold field values, required to draw emission current density of ∼1 μA/cm² were found to be 1.44, 1.36 and 1.5 V/μm for nanowires synthesized using 0.002, 0.004 and 0.016 M electrolyte concentrations, respectively. All Folwer–Nordheim (F–N) plots showed non-linear behavior indicating semiconducting nature of the emitters. The ZnO nanowires exhibited good emission current stability at the pre-set value of ∼10 μA over a duration of 6 h. The simplicity of the synthesis route coupled with the promising emission properties made the electrochemically synthesized ZnO nanowires a suitable candidate for high-current density applications.     

Nanohydroxyapatite synthesized from calcium oxide and its characterization

Spherical and nano-sized hydroxyapatite (HAp) was synthesized from calcium oxide by a continuous rapid precipitation method without using any secondary route. The maximum particles have a size around 10 nm according to X-ray diffraction (XRD), 35 nm based on scanning electron microscopy (SEM) and 15 nm according to transmission electron microscopy (TEM) studies. The sintering effects on structural properties of HAp were studied by XRD, Fourier transformation infrared (FTIR), ³¹P solid-state nuclear magnetic resonance (NMR) and Raman spectroscopy. The particle size varied from 5 to 70 nm and nanopores from 10 to 450 nm were revealed by SEM and transmission electron microscopy TEM. This result was also strongly supported by XRD study. The combined effect of heating and centrifuging force exerted by vigorous magnetic stirring causes the dispersion of tiny crystals followed by precipitation to form spherical shaped particles. The chemical structure of HAp was established by FTIR, NMR and Raman spectroscopy.