共沉淀-超临界干燥法制备纳米Cu/3Y-ZrO2复合材料及脱硫性能研究

研究了共沉淀-超临界干燥法得到的Cu/3Y-ZrO2纳米材料的结构和物相变化,并在模拟烟气中采用气相色谱仪对其脱除SO2的性能进行了比较研究.结果表明,以氨水为沉淀剂,采用共沉淀-超临界干燥法所得的中间产物,经真空热处理后,晶形发育较好且团聚较少,但在铜摩尔负载量为30%以上时才出现以金属Cu形式存在的铜组分衍射峰.铜组分负载量大、比表面积最小的产物,表现出脱硫效率最高;而铜组分负载量小、比表面积最大的产物脱硫活性却最差.总体而言,纳米Cu/3Y-ZrO2催化吸收剂的脱硫率随温度的上升而迅速增加,并在中温(300℃~500℃)脱硫率达到最大值,其稳定性也较好.     

热分解法制备超细活性氧化铝

分别采用超临界流体干燥和真空干燥,经煅烧制备γ-Al2O3粉体,再用TEM和XRD考察不同制备途径对产物晶态、形貌、尺寸的影响.结果显示,①超临界流体干燥能有效地对γ-Al2O3前驱体粉体进行脱水,防止硬团聚的形成.该前驱体在800℃下煅烧2h可制得纤维状及球形、分布较均匀、轻度团聚的γ-Al2O3超细粉体,其纤维长度50～200nm,直径约5～15nm,球形颗粒直径介于30～100nm之间.②真空干燥将导致γ-Al2O3硬团聚.     

纳米掺锶羟基磷灰石的制备及其抗菌性能研究

以硝酸钙、氯化锶、磷酸氢二氨等为原料,采用溶胶-凝胶-超临界流体干燥法,制备了纳米掺锶羟基磷灰石(SrHAP).通过元素含量分析、TEM、XRD、FT-IR等手段对其结构进行了表征,分析了锶的掺入对羟基磷灰石(HAP)的结构、晶形及结晶度的影响;研究了HAP掺入锶后对大肠杆菌、金黄色葡萄球菌、乳酸杆菌的抗菌性能.结果表明:采用溶胶-凝胶-超临界CO2干燥法,可制备结晶性较好的纳米HAP和Sr/[Sr Ca]原子比为0.5的纳米SrHAP;在给定的条件下,锶可以按化学计量比掺入到HAP的结构中;HAP掺入锶后,其主要官能团红外光谱吸收峰的振动频率降低,晶形从HAP的短棒状改变为SrHAP的针状,结晶度降低,对大肠杆菌、金黄色葡萄球菌、乳酸杆菌的抗菌性能提高.     

纳米掺锶羟基磷灰石的制备及其抗菌性能研究

以硝酸钙、氯化锶、磷酸氢二氨等为原料,采用溶胶-凝胶-超临界流体干燥法,制备了纳米掺锶羟基磷灰石(SrHAP)。通过元素含量分析、TEM、XRD、FT-IR等手段对其结构进行了表征,分析了锶的掺入对羟基磷灰石(HAP)的结构、晶形及结晶度的影响;研究了HAP掺入锶后对大肠杆菌、金黄色葡萄球茵、乳酸杆菌的抗茵性能。结果表明:采用溶胶-凝胶-超临界CO_2干燥法,可制备结晶性较好的纳米HAP和Sr/[Sr ca]原子比为0．5的纳米SrHAP;在给定的条件下,锶可以按化学计量比掺入到HAP的结构中;HAP掺入锶后,其主要官能团红外光谱吸收峰的振动频率降低,晶形从HAP的短棒状改变为SrHAP的针状,结晶度降低,对大肠杆菌、金黄色葡萄球菌、乳酸杆茵的抗菌性能提高。     

液相共沉淀制备镍铁尖晶石前躯体工艺研究

本文对于溶液均相共沉淀法制备镍铁尖晶石前躯粉体的工艺进行了探索研究。论文以Fe（N02）3和Ni（N02）2的混合溶液为反应物,滴加沉淀剂,进行共沉淀反应。对得到的沉淀产物进行洗涤、过滤、干燥、研磨、压制、烧结制备NiFe2O3尖晶石陶瓷粉体。通过正交试验确定了在共沉淀过程中影响共沉淀颗粒粒度的影响因素的主次顺序依次为：反应温度、搅拌速度、沉淀剂浓度、金属离子浓度;并通过反应温度和沉淀荆浓度对产率的影响试验,最终得到共沉淀反应沉淀的最佳条件。对于所制得的镍铁尖晶石陶瓷粉体检测结果表明：溶液均相共沉淀法得到的镍铁尖晶石前躯体粉末具有纯度高、粒度细的特点,并且制备出的镍铁尖晶石惰性阳极基体材料的强度显著提高。     

用改进的液相沉淀法制备ZnS纳米晶

以ZnSO4、（NH4）2S为原料，通过加入分散剂对传统的液相沉淀法进行改进，制备出ZnS的纳米粉末，并探讨了制备过程中沉淀、洗涤、干燥以及晶化等阶段的反应条件对产物的影响。结果表明：以丙三醇为分散剂、原料配比（n(ZnSO4)/n((NH4)2S)杰1：0.9、料液浓度比1：1，c(ZnSO4)、c((NH4)2S)均为0.2mol/L时为沉淀适宜工艺条件；干燥前对沉淀物用无水乙醇进行脱水处理，可有效地控制硬团聚体的产生；沉淀经400-600℃晶化1h，可得立方晶形β-ZnS纳米晶，产物为均匀球形，分散性较好；400℃晶化的产物晶粒尺寸约为40nm；600℃晶化的产物晶粒尺寸约为50nm。     

纳米Al2O3/ZrO2复合粉体的制备及表征

高性能的复合粉体是制备纳米复相陶瓷材料的关键.采用醇-水溶液加热法结合共沉淀过程制备纳米Al2O3/ZrO2复合粉体,研究了不同沉淀剂对粉体团聚的影响,利用透射电镜、X射线衍射、热重-差热分析、比表面积测定等技术对获得的纳米复合粉体进行了表征.结果表明:采用NH4HCO3作为沉淀剂可以得到几乎无团聚的碱式碳酸盐前驱物,该前驱物在煅烧过程中的物相变化显示四方相氧化锆(t-ZrO2)的形成温度大幅度地提高,同时在较低温度下生成了α-Al2O3,在1 100℃转变为t-ZrO2相和α-Al2O3相;粉体中两相颗粒分散良好、粒径一致、无硬团聚,其平均粒径为15～20 nm,比表面积为69.5 m2·g-1.     

锰锌铁氧体磁流体制备过程中OH-影响规律的研究

采用化学共沉淀法制备了Mn0.78Zn0.22Fe2O4z磁流体,全面分析并探讨了沉淀剂OH-的加入量对于溶液中金属离子共沉淀过程的影响规律及其作用机理.结果表明,溶液中Mn2+、Zn2+及Fe3+的沉淀过程与沉淀剂OH-的加入量密切相关,要保证上述离子的共同沉淀,沉淀剂OH-的加入量必须保证一定的过量比;当OH-过量比达到0.25时,可以保证溶液中金属离子的完全共同沉淀,此时,所制备磁流体的磁性能最好.当OH-过量比超过0.25以后,由于Zn2+不完全沉淀,导致反应产物的化学成分偏离规定的化学计量比,所制备磁流体的磁性能下降.     

铜掺杂磷酸锌钠的制备及其太阳光反射性能研究

采用共沉淀法制备铜掺杂磷酸锌钠作为热反射材料,通过XRD、SEM、UV-VIS-NIR分光光度计对产物进行表征,探讨了溶液p H值、掺杂量与热处理温度对产物晶体结构、表面形貌以及反射性能的影响。结果表明,当溶液p H从6增加到10时,样品NaZn0.5(Cu)_(0.5)PO_4的近红外反射率先升高后降低,当溶液p H值为9时,其近红外反射性能最优;随着铜掺杂量的增加,样品Na Zn1-x(Cu)_xPO_4的近红外反射率先升高后降低,当x=0.5时,其近红外反射率最高;热处理温度从400℃升高至700℃后,样品Na Zn0.5(Cu)0.5PO4的近红外反射率逐渐升高,经700℃热处理后近红外反射率高达60.4%。     

交叉共沉淀法制备Skutterudite纳米粉体的研究

探索了交叉共沉淀法制备纳米方钴矿化合物CoSb₃. 以钴和锑的氯化物为原料, NaOH和氨水为沉淀剂, 室温下调节pH=5~10, 经过滤、洗涤、超声分散和真空干燥后得到了Co(OH)₂和Sb₂O₃前驱体. 研究了还原热处理过程中还原气氛、温度、时间、原料配比对还原产物的相组成和粉体粒径的影响. 结果表明, 采用纯H₂为还原气氛, 500℃下还原3h, 当Sb/Co摩尔比为3.15时, 可得到粒径均匀、平均粒径约为100nm的单相CoSb₃粉体.     

Elemental blended powders semisolid forming of Ti-Al based alloys

Ti-6Al and Ti-6Al-4V alloys fabricated by semisolid forming are investigated with microscopic observation, density measurements, X-ray diffraction and mechanical property tests. The effects of the forming pressure, the forming temperature, and the forming loading time on the density of the green compacts are discussed. The shaped green-compact that is prepared by semisolid forming method transforms into intermetallics during the further alloying heat treatment. Pore-free green compacts are obtained under almost all the selective forming conditions. However, pores often appear after alloying heat treatment. The forming loading time has a relatively strong influence on the density of the compact. Experiments have also been carried out on various alloying treatments and the effects of the alloying treatment conditions on the mechanical properties of the compacts. It has been demonstrated that Ti-6Al-4V alloy can be fabricated by semisolid forming and the optimum alloying treatment conditions are at 1473 K treating for 7.2 ks, which can result in the best ultimate tensile strength of 1050 MPa and the elongation of 10% in excess of that of the plastic materials.     

制备条件对纳米NiO微粉的影响

用化学沉淀法制备了纳米立方NiO的微粉 ,研究了介质 pH、不同沉淀剂和热处理温度对纳米NiO粒子大小和聚结状态的影响。用NaOH作沉淀剂 ,控制介质 pH为 9～10 ,经 2 70～ 30 0℃热处理 4h ,制备得到粒子尺寸约 5nm ,在水中易重新分散的纳米NiO微粉     

Influence of graphite oxide drying temperature on ultra-fast microwave synthesis of graphene

Ultra-fast synthesis of graphene has been reported by microwave assisted graphene oxide reduction. In this article, the graphene oxide was initially dried above room temperature. The initial heat treatment of graphene oxide demonstrates a distinct improvement of exfoliation rate of graphene sheets. This method provides an efficient way for mass production of high quality graphene sheets. Raman spectroscopy, scanning electron microscopy, and X-ray diffraction techniques has been used to characterize reduced graphene sheets. The quality of reduced graphene was found to be affected by the initial drying temperature of graphite oxide.     

Morphology,Oxidation, and Mechanical Behavior of Nanoporous Cu Foams

Nanoporous copper foams (65–80% porosity) are synthesized by dealloying different copper alloys, including Cu₂₀Zn₈₀, Cu₃₅Zn₆₅, and Cu₃₀Al₇₀. Ligament sizes, porosity, and oxide content are examined by scanning electron microscopy, Raman spectroscopy, and X‐ray powder diffraction to determine the nanoporous foam's structure and thermal stability. The pores and ligaments of the copper foams can range in size from 35 to 220 nm. Both parameters can be controlled by either the dealloying process or a subsequent heat treatment. The results show no copper oxide peaks for the as‐prepared samples; however, any heat treatments above 200 °C lead to the formation of Cu oxide (CuO and Cu₂O). These foams are shown to retain their structural integrity even after oxidation. A novel method is thus developed for synthesizing nanoporous Cu oxide foams by heat treating nanoporous copper.     

Grain size dependence of dielectric properties of ultrafine BaTiO3 prepared by a sol-crystal method

Ultrafine BaTiO3 prepared by a decomposition of an organometallic crystal with unity of Ba/Ti ratio (sol-crystal method) has been characterized. While the as-prepared product resulting from the decomposition of the organometallic crystal at room temperature was BaTiO3 with pseudo-cubic structure, the well-crystallized tetragonal polymorph was obtained by firing the as-prepared product above 1000°C. Residual organic compounds, CO2-3 and OH- ions in the samples prevent the grain growth and tetragonal distortion of BaTiO3. We obtained quite higher room temperature permittivity (3700) at 1 kHz for the sample fired at 1200°C than that (630) prepared by conventional solid-state reaction starting from BaCO3 and TiO2. Such a high value was probably due to the accomplishment of homogeneous cation stoichiometry, which was achieved by this preparation method via the organometallic crystal with stoichiometric Ba/Ti ratio. This revised version was published online in November 2006 with corrections to the Cover Date.     

喷雾干燥法金刚石-陶瓷结合剂复合烧结体的制备及表征

以金刚石和无机溶胶为原料,采用喷雾干燥法制备金刚石-陶瓷结合剂复合粉体,将粉体压制、烧结,获得金刚石-陶瓷结合剂烧结体。采用扫描电镜和激光粒度分析仪对复合粉体的形貌和粒径分布进行表征,借助综合热分析仪选取复合体的烧结温度,利用抗折试验机、扫描电镜和X射线衍射分别对喷雾干燥法和熔融法所制烧结试样的抗弯强度、断面形貌及物相进行分析。结果表明:经喷雾干燥的复合粉体为球形,易于成型,且复合粉体尺寸分布范围较宽,利于提高坯体致密度;选取金刚石-陶瓷结合剂复合体的烧结温度为820℃,在此温度下结合剂可实现对金刚石的黏结和包裹;烧结后,随陶瓷结合剂含量增加,两种工艺所制试样的抗弯强度均有提高,气孔率都相应降低;当结合剂含量为32%(质量分数)时,喷雾干燥法所制烧结试样的微观结构均匀,易析晶,抗弯强度和气孔率分别为99.46MPa和38.55%;熔融法所制试样的抗弯强度和气孔率分别为72.42MPa和39.89%。     

Properties of copper-detonation nanodiamond composites obtained by spray drying

Nanostructural copper-detonation nanodiamond (DND) composites have been obtained by the method of spray drying. The technological process consists in spraying and drying a mixture of an aqueous copper salt solution and DND suspension, followed by thermal treatment in a reductive atmosphere. The DND content in copper powder was varied from 0.5 to 5.0 mass %. The average DND particle size in suspension was 4–6 nm. Copper-DND nanocomposite powders consist of nearly spherical particles with average size within 20–30 μm. Composition and structure of obtained materials have been studied.     

电喷雾法制备药物-高分子固体分散体

以灰黄霉素（GRIS）-聚乙烯吡咯烷酮（PVP）体系为例,研究了电喷雾法制备药物-高分子固体分散体,并采用偏光显微镜（POM）、X射线衍射仪（XRD）和差示扫描量热仪（DSC）等方法对体系进行表征。电喷雾法制备得到的微米级固体分散体样品中,体系玻璃化转变温度,很好地符合半经验公式Fox方程,说明GRIS在体系中分散均匀...     

柠檬酸助微波水热法制备纳米ZnS及其光催化性能研究

以锌粉和硫化钠为原料,利用柠檬酸助微波水热法制备得到了纳米ZnS光催化剂。XRD、TEM、PSD、FTIR分析结果表明,获得的产品属于高纯的立方形(闪锌矿)晶相,微粒粒径小,粒径分布窄。与水热法相比,反应时间明显缩短。CBW水溶液的光催化降解活性测试结果证实,与直接水热法获得的ZnS光催化剂相比较,微波水热法制得的产品表现出更高的催化活性。