亚微米级TATB的制备工艺条件对其粒径的影响

采用溶剂-非溶剂法制备亚微米级TATB,探讨了工艺条件对亚微米级TATB粒径的影响.通过单因素和正交试验对各种影响因素进行了研究,并测试了产品细化前后的能量输出变化.结果表明,影响TATB粒径的主要因素为溶液的质量浓度、溶液与水的温度差、搅拌速率、溶液滴加速率、干燥方式.通过正交实验得到最佳工艺条件为:溶液的质量浓度为23.6 g/100 mL,温度差70℃,搅拌速率1600 r/min,滴加速率为0.75 mL/s,真空冷冻干燥.产品的粒径在较大程度上取决于溶液与水的温度差.细化TATB的能量输出较原料有一定程度的提高.     

联碱碳化塔洗水制备轻质碳酸钙

为了回收联碱厂碳化塔洗水中的CO32--、HCO3-,减少污染物排放,采用复分解法,以碳化塔洗水为原料与饱和氢氧化钙溶液反应制备轻质碳酸钙.通过正交试验和单因素试验探讨了碳化塔洗水滴加速率、反应温度、搅拌速率、添加剂对产物粒径的影响;通过SEM、XRD分析了产物形貌及性质.试验结果表明,在碳化塔洗水以3 mL/min的速率滴加、反应温度为15℃、搅拌速率为700 r/min、op-10的投加量为Ca（OH）2溶液质量分数的0.1％的最佳反应条件下,得到的产物粒径为0.3 ～ 1.0 μm,颗粒分散均匀,粒度分布较窄,晶型为四方形片块状轻质碳酸钙.以碳化塔洗水为原料与饱和氢氧化钙溶液反应制备轻质碳酸钙,为联碱厂废水的处理及资源综合利用提供了新途径.     

均匀沉淀法制备纳米氧化锌和片状氧化锌粉体

以氯化锌、尿素为原料 ,采用均匀沉淀法在一定条件下制备得到纳米级氧化锌粉体。并以TEM、SEM、XRD等测试手段对产物的粉体结构、形貌进行了研究。结果表明 ,在 2 0 0℃下热处理得到的氧化锌粉体结晶性能良好 ;在较大的反应物浓度及反应物浓度比下可以得到较小的晶体粒径 ,平均为 2 0nm ,且分散性好 ;在较小的浓度及较小的浓度比下得到的晶体粒径较大 ,并呈片状生长。阐述了浓度对于粒径大小的影响并得出片状氧化锌微晶生长的最佳条件。     

锌灰酸浸净化制氯化锌新工艺研究

研究了以炼铅厂铅锌烟灰为原料,采用盐酸浸取并以高锰酸钾氧化铁锰、锌粉置换镉铅铜两步法生产氯化锌的新方法。以锌浸出率最高、铅浸出率最低、铁锰镉铅铜除杂最彻底为考察目标,通过实验找到最佳工艺条件:40 g铅锌烟灰在由71 m L浓盐酸和130 m L水配制的混酸中在30℃条件下浸取50 min,然后加入高锰酸钾0.017 g在10℃条件下继续反应2 h,过滤后的滤液中加入锌粉0.15 g在40℃条件下反应50 min,过滤得到浓度为1.65 mol/L的氯化锌溶液。在上述工艺条件下锌的浸出率为95.4%。用制备的氯化锌溶液生产氧化锌,杂质含量满足GB/T 19589—2004《纳米氧化锌》一级品要求。     

柠檬酸三钠对低钠光卤石分解制备氯化钾晶体粒度影响研究

针对光卤石分解制备的氯化钾晶体平均粒径小导致过滤、洗涤损失大以及干燥能耗高的问题,以柠檬酸三钠为成核抑制剂,考察了柠檬酸三钠添加浓度、加入光卤石溶液的浓度、搅拌速率、停留时间、加入光卤石溶液的体积、加液速率对氯化钾晶体粒度的影响。在单因素实验的基础上采用3因素3水平的Box-Behnken响应面优化设计方法做了研究。结果表明：在柠檬酸三钠添加浓度为0.007 mol/L、加入光卤石溶液质量浓度为0.759 g/mL、搅拌速率为372.52 r/min、停留时间为40 min、加入光卤石溶液体积为100 mL、加液速率为2 mL/min的条件下可制得平均粒径为595.892 μm的氯化钾晶体,是未添加柠檬酸三钠、其他实验条件不变时所得氯化钾产品的平均粒径（351.607 μm）的1.69倍,并且氯化钾产品纯度为95.82%,符合GB/T 7118—2008《工业氯化钾》质量标准要求。实验结果为提高氯化钾产品的粒度提供参考。     

制备条件对氢氧化镁和碱式氯化镁组成和形貌的影响

以六水氯化镁和氨水为原料,水热法合成出了氢氧化镁和碱式氯化镁晶须。利用XRD、SEM、TG、FT-IR对产物的组成和形貌进行表征,同时考察了原料浓度、反应温度、反应时间及表面活性剂对产物形貌的影响。结果表明,在低氯化镁浓度和一定氨水滴加量的条件下产物为厚度20～50 nm,具有规则形状的纳米六方片层及其组合玫瑰花球结构的氢氧化镁,增大氯化镁溶液浓度同时减小氨水滴加量产物为直径0.5 μm、长度200 μm的碱式氯化镁单晶。     

镍封新工艺——复合电镀镍–硫酸钡

在普通光亮镍镀液中直接滴加钡配合物溶液(柠檬酸钠+氯化钡)制备含有硫酸钡微粒的复合镀镍(镍封)液。探讨了钡配合物溶液滴加量、滴加速率、温度和搅拌强度对后续微孔铬镀层微孔密度的影响。配制镍封液的较优工艺条件为:滴加量10 m L/L,滴加速率30 s/m L,搅拌强度4级,温度40°C。该镍封工艺简单可行,可以获得Ba SO4粒径基本一致、均匀镶嵌的Ni–Ba SO4复合镀层,最终制得微孔密度高、耐蚀性好的微孔铬镀层。为防止该工艺所得镍封液在存放过程中微粒间发生团聚而影响铬镀层的微孔密度和耐腐蚀性,还需要寻找合适的分散剂。     

水解沉淀法制备超细碱式碳酸锌的试验研究

以碳酸氢铵和氨水浸出锌灰,然后经除杂净化得到高纯锌氨溶液,以高纯锌氨溶液为原料,采用加热水解沉淀法合成超细碱式碳酸锌,碱式碳酸锌经煅烧得到超细氧化锌。研究了加热水解沉淀工艺条件对碱式碳酸锌的粒径分布的影响。结果表明,最佳工艺条件为：搅拌速度为300 r/min、蒸氨温度为90 ℃、锌氨溶液中锌质量浓度为75 g/L、负压为-2 kPa。最佳工艺条件下得到的碱式碳酸锌的D50为0.77 μm,颗粒近似球形;煅烧后的氧化锌为六方晶系纤锌矿结构,D50为0.69 μm。     

基于正交设计的羟基磷灰石生物陶瓷材料的制备研究

文章以硝酸钙和磷酸氢二铵为原料,采用化学沉淀法制备了超细羟基磷灰石微粒,通过正交试验设计,结合红外光谱(FTIR)、粒度分析、X-射线衍射(XRD)对产物的表征,探讨了反应温度、反应物浓度、滴加速率和反应时间对羟基磷灰石的结晶情况、结晶尺寸及粒度的影响。结果表明:四因素影响次序依次为溶液浓度温度滴加速率反应时间。反应温度在20℃,磷酸氢二铵的滴加速率为100 m L/min,反应物浓度为0.5 mol/L,反应时间5 h时,形成粒径最小的羟基磷灰石,小范围的p H的波动对形成羟基磷灰石的影响不大。     

废锌催化剂的铵盐浸出工艺

废锌催化剂是一种含锌废弃物,可采用铵盐浸出工艺回收其中的锌资源。具体步骤：对废锌催化剂先进行预处理,以氯化铵为浸取剂,经浸取反应、过滤分离得到氯化锌溶液。实验得到适宜的工艺条件：废锌粒度为58~ 80 μm、氯化铵质量分数为17%、反应温度为60 ℃、反应时间为2 h。在此条件下,锌浸出率达95.2%,镍残存率为0.7%,实验证实了氯化铵溶液作为浸取剂的优势。XRD测试表明,前驱体为Zn₄CO₃（OH）₆·H2O,得到的样品是氧化锌粉体,粉体粒径为63 nm,纯度为99.3%。     

Synthesis of Nanocrystalline Lithium Zinc Ferrites Using Polyacrylic Acid, and Their Initial Densification

A chemical synthesis technique that uses polyacrylic acid (PAA) to prepare nanocrystalline Li_0.3Zn_0.4Fe_2.3O₄ was investigated. Phase-pure spinel that had an average particle size of ∼13 nm was synthesized at a low temperature (450°C) for 30 min. The average particle size was dependent on the firing temperature and amounts of PAA and Bi₂O₃. The combustion reaction of PAA was believed to be the main reason for the low-temperature synthesis of nanocrystalline lithium zinc (LiZn) ferrites. In addition, a chelating tendency was observed, via infrared (IR) spectroscopy, in the dried gel precipitates that were prepared at a low pH (∼2). The initial densification behavior of the nanopowder compacts was studied using linear-shrinkage data. Densification of the nanopowder without Bi₂O₃ started at low temperatures (∼400°C). The addition of Bi₂O₃ to the nanopowder noticeably did not contribute to reducing the initial densification temperature. This result was supported by the activation-energy calculation for the initial densification. Compared to an activation energy of 280 kJ/mol for grain-boundary diffusion of the nanopowder without Bi₂O₃, a higher value (430 kJ/mol) was obtained in the case of the 3 wt% Bi₂O₃-containing nanopowder.     

Hydrothermal Synthesis of BaTiO3 Nanopowders Using TiO2 Nanoparticles

Anatase TiO₂ nanoparticles, obtained by hydrolyzing titanium isopropoxide in distilled water, were used to synthesize BaTiO₃ (BT) nanopowder by the hydrothermal method. When titanium isopropoxide was used, BT nanopowder with a low tetragonality of 1.0070 was formed because of the presence of OH^? ions in the oxygen sites and Ba vacancies. However, by changing the titanium source from titanium isopropoxide to TiO₂ nanoparticles, a homogeneous BT nanopowder with similar particle size and a high tetragonality of 1.0081 was synthesized. The size of the BT nanopowder particles was decreased by reducing the synthesis time. In particular, the BT nanopowder that was synthesized at 220°C for 16 h with a Ba/Ti molar ratio of 4.0 exhibited a high tetragonality of 1.0083 and a small particle size of 126.0 nm.     

掺锑氧化锡纳米粉体的制备与表征

以SnCl4·5H2O和SbCl3为原料,NH3为共沉淀剂,在表面活性剂存在下,采用室温固相法制备锑掺杂二氧化锡(ATO)纳米粉体。探讨了掺锑量、表面活性剂对ATO粉体性能的影响。运用IR、XRD、TEM、比表面仪(BET)等对ATO粉体进行了表征。结果表明,当锑掺杂量为12.3%时,ATO纳米粉体具有最小电阻率,为3.36Ω·cm,ATO粉体为四方晶红石结构,颗粒形状为近似球形,粒度均匀,一次粒径为10 nm左右。     

液相沉淀法制备In2O3纳米粉

以无机盐为原料,采用液相沉淀法制备纳米In2O3粉体,研究了沉淀反应条件及沉淀后处理等对纳米In2O3粉体质量的影响.利用TG-DSC,FT-IR,XRD,SEM和EDS等分析手段对所制纳米In2O3粉体的结构、粒度、形貌、成分等进行了表征.结果表明:该法制备的In2O3纳米粉具有立方晶系结构、纯度较高、颗粒均匀呈球形、分散性良好、平均粒径为80 nm左右.     

Synthesis and characterization of chlorapatite–ZnO composite nanopowders

The influence of zinc oxide content on the formation of chlorapatite-based composite nanopowders in the mechanically alloyed CaO–CaCl₂–P₂O₅–ZnO system was studied. To mechanosynthesize composite nanopowders, different amounts of hydrothermally synthesized zinc oxide nanoparticles (0–10 wt%) were mixed with ingredients and then were mechanically activated for 5 h. Results showed that in the absence of zinc oxide, high crystalline chlorapatite nanopowder was obtained after 5 h of milling. In the presence of 4 and 7 wt% zinc oxide, the main product of milling for 5 h was chlorapatite–zinc oxide composite nanopowder. On increasing the zinc oxide content to 10 wt%, composite nanopowder was not formed due to improper stoichiometric ratio of the reactants. The crystallite size, lattice strain, volume fraction of grain boundary, and crystallinity degree of the samples fluctuated significantly during the milling process. In the presence of 7 wt% zinc oxide, the crystallite size and crystallinity degree reached 51±2 nm and 79±2%, respectively. During annealing at 900 °C for 1 h, the crystallization of composite nanopowder occurred and as a result the crystallinity degree rose sharply to 96±3%. In addition, the crystallite size increased to 77±2 nm after annealing at 900 °C. According to SEM and TEM images, the composite nanopowder was composed of both ellipse-like and polygonal particles with a mean size of about 98 nm.     

单分散纳米硫酸锶粉体的制备

利用过饱和溶液存在介稳区且其宽度可调节的原理,使反应物在沉淀形成前充分微混,制备出纳米硫酸锶粉体.分析了反应条件的改变对产品粒径和粒度分布的影响,利用正交试验确定适宜的工艺条件.产品用TEM及X射线粉末衍射进行表征,并测定其粒度分布.结果表明：通过改变溶液介稳区宽度可以制备粒度分布窄、晶型一致的纳米硫酸锶粉体.并从唯象层面上推测了向反应体系中加入EDTA和乙醇的作用机理.     

氧化铟纳米粉制备及表征研究

以无机盐为原料，采用液相沉淀法制备纳米氧化铟粉体。研究了沉淀反应条件及沉淀后处理等对纳米氧化铟粉体质量的影响，利用TG-DSC、FT-IR、XRD、SEM和EDS等分析手段对所制纳米氧化铟粉体的结构、粒度、形貌、成分等进行了表征。结果表明：该法制备的氧化铟纳米粉具有立方晶系结构、纯度较高、颗粒均匀呈球形、分散性良好、平均粒径为50nm左右。     

Computational Fluid Dynamic Modeling of a Flame Reaction Process for Silica Nanopowder Synthesis from Tetraethylorthosilicate

The process of synthesizing silica nanopowder by the gas phase thermal oxidation of tetraethylorthosilicate in a diffusion flame reactor was simulated using a commercial computational fluid dynamic code. The fuel combustion process and silica particle formation and growth in the flame were modeled. The temperature, velocity, and particle size distribution (PSD) fields inside the reactor were computed. Chemical reaction rate and a population balance model were used to calculate the particle formation and growth and PSD. Satisfactory results were obtained for the temperature profile and PSD. Computed values of the average size of the final products were consistent with those obtained in a previous experimental work.     

Synthesis and characterization of bioactive forsterite nanopowder

Forsterite ceramic is a new bioceramic with good biocompatibility. However, the degradation rate of forsterite ceramic is extremely low, and the apatite-formation ability is also poor. On the other hand, nanostructured bioceramics are expected to have better bioactivity than coarser crystals. The aim of this work was preparation, characterization and bioactivity evaluation of forsterite nanopowder. Forsterite nanopowder was synthesized by the sol–gel process. Bioactivity evaluation was preformed by immersing the forsterite powder in the simulated body fluid (SBF) and apatite formation on the surface of the immersed forsterite nanopowders was investigated. Results showed the particle size of pure forsterite was 25–45 nm. During immersion in SBF, the dissolution rate of the forsterite nanopowder was higher than conventional forsterite powders and apatite was formed after soaking for 14 days. Our study indicated that forsterite nanopowder unlike micron-sized forsterite possessed apatite-formation ability and might be used for preparation of new biomaterials.     

Effect of vibro-milling time on phase formation and particle size of barium titanate nanopowders

Barium titanate (BT) nanopowder was synthesized by a solid state reaction via a rapid vibro-milling technique. The effect of milling time on phase formation and particle size of BT powder was investigated. Powder samples were characterized using XRD (X-ray diffraction) and SEM techniques. It was found that the resulting BT powders have a range of particle size depending on milling times. Production of a single-phase BT nanopowder can be successfully achieved by employing a combination of 30 h milling time and calcination conditions of 1200 °C for 2 h.