高活性纳米铝粉HTPB-TDI包覆组装与表征

采用复合型喷雾造粒工艺对制备态高活性纳米铝粉进行了HTPB-TDI包覆造粒研究,用扫描电子显微镜(SEM)、能谱仪(EDS)、透射电子显微镜(TEM)等对包覆造粒结果进行了表征。结果表明,在包覆剂与活性纳米铝粉质量比为1∶2和1∶5的两种情况下都能实现对高活性纳米铝粉的包覆组装造粒,包覆剂能够高覆盖纳米铝粉表面,且均匀铺展在纳米铝粉表面,厚度分别达到10和5 nm,能很好阻隔或延缓外界氧与纳米铝粉的反应,有望实现高活性纳米铝粉的长期存储。随着包覆剂含量的减少,在相同的组装工艺条件下,组装造粒颗粒品质随之提高,组装颗粒平均粒径减小,但颗粒球型度随之提高。在1∶5的配比下,包覆组装颗粒的活性铝含量超过72%,活性铝含量高,因此,可通过配比和工艺控制进一步提高包覆组装颗粒活性铝含量,实现高活性纳米铝粉在推进剂中的应用。     

薄层纯化纳米铝粉及特性研究

NiAl复合材料热喷涂涂层可以作为陶瓷涂层的粘结底层和抗氧化面层。采用蒸发冷凝方法制备了平均粒度为80 nm的铝粉。把纳米铝粉作为外包覆材料得到铝包镍复合粉末。SAXS检测纳米铝粉的粒度,SEM、HRTEM、TG-DSC检测了纳米铝粉、复合粉末和涂层的结构。表明纳米铝粉包覆材料成分均匀、包覆完整,熔化反应温度更低,放出较多的热量。制备的涂层致密、均匀,为典型的层状结构,与基体的结合强度好。     

不锈钢表面钝化膜特性的研究进展

金属钝化膜的研究已从宏观研究进展到结构和组成等微观研究阶段.通过不锈钢表面自发形成的薄而稳定的钝化膜主要由金属氧化物组成.钝化膜的厚度由不锈钢的成分、溶液pH值、电位、电解液和温度等因素决定,一般不超过10 nm.综述了不锈钢表面钝化膜的厚度、组织和结构,钝化膜的形成和生长机理、半导体性能和耐蚀性,讨论了纳米结构对不锈钢钝化膜性能的影响.当前研究重点是开发高强度和耐磨性、更好耐蚀性的新型不锈钢,而采用纳米技术是有效途径之一.     

金纳米颗粒烧结的分子动力学模拟

采用分子动力学模拟方法研究了不同尺寸Au纳米颗粒在烧结过程中晶型转变及烧结颈长大机制.研究发现纳米颗粒的烧结颈生长主要分为两个阶段:初始烧结颈的快速形成阶段和烧结颈的稳定长大阶段.不同尺寸纳米颗粒烧结过程中烧结颈长大的主要机制不同:当颗粒尺寸为4 nm时,原子迁移主要受晶界（或位错）滑移、表面扩散和黏性流动控制;当尺寸在6nm左右时,原子迁移主要受晶界扩散、表面扩散和黏性流动控制;当颗粒尺寸为9 nm时,原子迁移主要受晶界扩散和表面扩散控制.烧结过程中Au颗粒的fcc结构会向无定形结构转变.此外,小尺寸的纳米颗粒在烧结过程中由于位错或晶界滑移、原子的黏性流动等因素会形成hcp结构.      

铝粉表面的氧化物薄膜对烧结和抗拉强度的影响

三种粒度小于 10 μm的铝粉样品 ,实验编号分别是AF、GF和CPGF ,其中AF铝粉的化学纯度为 99 7% ,以气雾化方法制得 ,AF铝粉的表面有一层较厚的氧化物薄膜 (约 10～ 2 0nm) ,GF为高纯铝粉 ,化学纯度为 99 99% ,CPGF为商业纯铝粉 ,GF和CPGF铝粉表面氧化物薄膜的厚度约为 3～ 5nm ,将上述三种铝粉以热压法在 5 0 0℃、175MPa的压力下压制成形。由于GF和CPGF铝粉表面的氧化膜较薄 ,有利于烧结 ,用GF和CPGF铝粉所制样品比用AF铝粉制作的样品具有较高的密度和更好的延展性 ,用GF和CPGF铝粉制作的样品中孔洞较少 ,颗粒间粘接的…     

废铝液制备水合硅酸铝及其表面修饰

本研究以工业废铝液作为原料,通过反应合成、老化、洗涤、表面修饰等步骤,制备出水合硅酸铝,对差热、SEM等样品进行了化学分析,得出:修饰后样品粒子可达到纳米量级,各项指标均符合通用企业标准要求;加入Tween-80后,其以吸附形式附在硅酸铝颗粒表面,从而起到修饰作用;本体系中硅酸铝的生长过程分为四个阶段,分别受不同工艺条件的控制。     

废铝液制备水合硅酸铝及其表面修饰

本研究以工业废铝液作为原料,通过反应合成、老化、洗涤、表面修饰等步骤,制备出水合硅酸铝,对差热、SEM等样品进行了化学分析,得出:修饰后样品粒子可达到纳米量级,各项指标均符合通用企业标准要求;加入Tween-80后,其以吸附形式附在硅酸铝颗粒表面,从而起到修饰作用;本体系中硅酸铝的生长过程分为四个阶段,分别受不同工艺条件的控制.     

粉末冶金泡沫铝制备相关参数研究

在粉末冶金发泡法制备泡沫铝的基础上,研究发泡剂、发泡温度等参数对泡沫铝制备的影响。结果表明,Ti H2的分解峰值温度与铝的熔点十分接近,为640℃,其分解的气体体积是相同质量Ca CO3的30倍,是一种制备高孔隙泡沫铝较好的发泡剂;通过比较研究,发现铝发泡的合适温度为700~750℃,发泡时间宜选择在900 s左右;铝粉表面氧化膜对泡沫铝产生影响,氧化膜质量分数在9.8%左右时,孔隙率达到最大值77%,在氧化膜质量分数为8.2%左右时,孔径最不均匀。     

废铝液制备水合硅酸铝及其表面修饰

本研究以工业废铝液作为原料，通过反应合成、老化、洗涤、表面修饰等步骤，制备出水合硅酸铝，对差热、SEM等样品进行了化学分析，得出：修饰后样品粒子可达到纳米量级，各项指标均符合通用企业标准要求；加入Tween-80后，其以吸附形式附在硅酸铝颗粒表面，从而起到修饰作用；本体系中硅酸铝的生长过程分为四个阶段，分别受不同工艺条件的控制。     

氧化锌纳米结构的热蒸发沉积合成及生长机理

以ZnO粉末为原料,用N2作为载气,采用无催化辅助的热蒸发法沉积制备ZnO纳米结构,分别用X线衍射仪、扫描电镜和透射电镜对ZnO的物相、形貌和结构进行表征,并结合晶体生长理论和实验条件,对ZnO产物的形貌变化和纳米带生长方向进行研究。结果表明:离气源较近的位置到离出口较近的位置,ZnO纳米结构的形貌由连续颗粒膜逐渐向纳米带、直径大于100 nm和直径小于100 nm的纳米线变化。特别是发现ZnO纳米带除了常见的[001]生长方向外,还有[101]和[203]两种极为罕见的生长方向,这些纳米带都具有上下表面均由(±010)晶面组成的特点。ZnO产物的形貌变化是其生长过程由动力学控制为主转向热力学控制为主的结果,纳米带生长方向不同,可能与其晶核形成过程中的竞争生长有关。     

Preparation and performance of CeO_2 hollow spheres and nanoparticles

CeO_2 hollow spheres were synthesized by polystryrene sphere(PS) templates and CeO_2 nanoparticles were prepared by a facile method. The as-obtained products were characterized by scanning electron microscopy(SEM), N_2 adsorption-desorption, X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR) and UV-vis diffuse reflectance spectra. The results showed that the structure of the obtained CeO_2 hollow spheres was hollow microsphere with a diameter of 380 nm and the average particle size of CeO_2 nanoparticles was about 1700 nm. The two samples' Brunauer-Emmett-Teller(BET) surface area was 67.1 and 37.2 m~2/g. The CeO_2 hollow spheres had a better performance than nanoparticles at UV-shielding because of higher surface area and the structure of hollow sphere.     

Synthesis and characterization of yttrium and antimony codoped SnO₂ conductive nanoparticles

Y was used as a dopant in preparing conductive powder to improve its performance. Y and Sb co-doped SnO2 conductive nanoparticles were prepared by the complexation-coprecipitation method with Sn,Sb2O3 and Y2O3 as the raw materials. Crystal phase,thermal behavior and structure of the prepared conductive nanoparticles were characterized by X-ray diffraction(XRD) ,thermal analysis(TG-DSC) ,Fourier transform infrared(FTIR) and transmission electron microscopy(TEM) techniques,respectively. The Y and Sb co-doped SnO2 conductive nanoparticles with a structure of tetragonal rutile had intense absorption in 4000-2500 cm-1,and the diameter ranged from 10 to 30 nm. The resistivity of Y and Sb co-doped SnO2 conductive nanoparticles was as low as 0.09 Ω·cm which was 4.6 times lower than that of Sb doped SnO2 conductive nanoparticles.     

Photoluminescence properties of LaF3：Eu^3＋ nanoparticles prepared by refluxing method

The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), UV-vis diffuse reflectance spectrum, and photoluminescence spectra. The results of XRD indicated that the obtained LaF3: Eu3+ nanoparticles were well crystallized with a hexagonal structure. The FE-SEM image illustrated that the LaF3: Eu3+ nanoparticles were spherical with an average size around 30 nm. Under irradiation of UV light, the emission spectrum of LaF3: Eu3+ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ (J=1, 2, 3, 4) transitions of the Eu3+ ions, with the dominating emission centered at 590 nm. In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies (-350 cm-1) of LaF3 matrix. The optimum doping concentration for LaF3: Eu3+ nanoparticles was determined to be 20mol.%.     

[Bmim]NTf2离子液体介质中Ni纳米粒子的制备与表征

在含有1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺盐([Bmim]NTf2)离子液体和pH11的水合肼-碳酸钠的还原性溶液中,Ni2+离子被还原为黑色的晶体Ni纳米粒子。通过XRD、TEM、TG和DTA对所制备的Ni纳米粒子进行分析,表明Ni纳米粒子呈不规则的类球形,为面心立方结构,具有较窄的尺寸范围,粒径3~32 nm。还原过程中,[Bmim]NTf2离子液体同时起到了溶剂和修饰剂的作用,在所生成的Ni纳米粒子的表面形成了修饰层,稳定了纳米颗粒粒径,阻止了纳米粒子之间的团聚,同时也提高了纳米粒子的热稳定性。     

离子液体[Bmim]PF6中铜纳米粒子的制备与结构表征

在离子液体l-丁基-3-甲基咪唑六氟磷酸盐([Bmim]PF6)介质中,Cu2+在抗坏血酸的还原作用下,制备了金属铜纳米粒子。通过XRD、TEM和TGA对铜纳米粒子结构的表征,表明铜纳米粒子呈球形,具有较窄的尺寸范围,粒径10~30 nm。在还原过程中,离子液体同时起到了溶剂和修饰剂的作用,在所生成的铜纳米微粒的表面形成了一层离子液体的修饰层,稳定了铜纳米颗粒粒径,阻止了铜纳米粒子之间的团聚,同时也提高了铜纳米粒子的热稳定性,这有利于拓宽铜纳米粒子应用的温度范围。     

Hydrothermal synthesis,structure study and luminescent properties of YbPO₄:Tb³⁺ nanoparticles

YbPO4:Tb3+ were synthesized by mild hydrothermal method.The luminescent properties,morphologies and structure of the obtained powders were characterized by photoluminescence(PL) spectra,FESEM,X-ray diffractometer(XRD) and FTIR.The results showed that the prepared YbPO4:Tb3+ nanoparticles were pure tetragonal phase and the average grain size varied with increasing of Tb3+ concentration.Hydrothermal temperature was revealed to be the key factor to enhance the emission intensity of YbPO4:Tb3+ phosphors.The spherical nanoparticles could be effectively excited by near UV(369 nm) light and exhibited green performance at 543 nm(5D4→7F5),489 nm(5D4→7F6) and 586 nm(5D4→7F4).The CIE chromaticity was calculated to be x=0.298,y=0.560.The YbPO4:Tb3+ nanoparticles exhibited potential to act as UV absorber for solar cells to enhance the conversion efficiency.     

微波辐射下纳米银粒子的制备及表征

以硝酸银为银源,六亚甲基四胺为还原剂,聚乙烯吡咯烷酮为表面活性剂和稳定剂,在微波辐射下制备出平均粒径约30nm的纳米银颗粒。利用X射线衍射仪、透射电子显微镜对样品的晶体结构和形貌进行表征;用红外吸收光谱对样品结构组成进行定性分析;用紫外-可见分光光度法研究样品的光学性能。结果表明:该法简单、快捷,所制备的纳米银粒子为纯立方晶型的多晶,其粒径小,分布窄,分散性好。     

Synthesis and photoluminescent properties of water-soluble TbF_3 nanoparticles

Monodispersed and water-soluble TbF3 nanoparticles were synthesized at a relatively low temperature in aqueous solution using citric acid as an additive,and characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM),Fourier transform infrared spectra(FTIR),photoluminescence(PL) spectra and lifetime.The as-prepared TbF3 nanoparticles had orthorhombic structure and were composed of monodispersed spherical particles with an average particle size of 50 nm.The excitation spectrum...     

金属Ni、Al纳米材料的制备及其表征

用爆炸法制备金属镍、铝纳米粉,对其纳米颗粒的形貌特征、成分、晶体结构等进行了实际测定,结果表明:Al的粒度分布比较窄,一般在30~80 nm,镍的粒度分布约30~100 nm。     

热分解法制备二硫化钼纳米粉末的研究

以硫钼酸铵为原料，热分解法制备出了二硫化钼纳米粉末，采用TEM，SEM，XRD和ED等方法检测了产物的形貌、组成、结构。结果表明：制备出的灰黑色二硫化钼纳米颗粒平均直径为几十纳米；XRD谱图与标准衍射谱比较，产物属六方晶系，a=0．316nm，c=1，229nm；基本无杂质，较纯净；ED分析还表明纳米颗粒为多晶，晶化程度好，(0004)、(011^-0)、(011^-2)等品面的衍射环连续、清晰，与XRD的分析结果一致。并对二硫化纳米粉末形成的影响因素如反应温度、反应时间、料层厚度、反应气体流速、反应物的粒度等进行了讨论。