绒球状结构氧化钨的制备

通过W粉和Ni(NO3)2·6H2O在钼包套内反应,制备出微米尺度的绒球状结构氧化钨.绒球状结构由长度达数百微米、外径1～10 μm的微米管和直径100～500 nm的亚微米纤维组成.X射线衍射和透射电子显微镜分析表明:产物为具有良好晶体结构的沿[010]方向生长的单斜结构的W18O49.这些通过Vapor-Solid(V-S)生长机制形成的绒球状结构氧化钨因为具有巨大的表面积,在微型半导体敏感元件方面具有巨大的应用前景.     

W_(18)O_(49)@Cu_2O纳/微米复合材料的制备及其光催化性能

首先用热蒸发方法制备了W_(18)O_(49)纳微米棒,然后经醋酸铜饱和溶液浸泡后再热处理在W_(18)O_(49)纳微米棒表面负载Cu_2O制得了W_(18)O_(49)@Cu_2O纳微米复合材料;采用X射线衍射仪、扫描电子显微镜、X射线能谱分析及透射电子显微镜对样品进行分析表征;最后选用亚甲基蓝溶液作为目标降解物,模拟污水处理测试材料的光催化性能。结果表明,W_(18)O_(49)纳微米棒在饱和醋酸铜溶液中浸泡时间越长,所得到的催化剂中Cu_2O的负载量越多,且所制备的W_(18)O_(49)@Cu_2O的纳微米复合材料相对于纯W_(18)O_(49)纳微米棒,其光催化效率得到了显著提高。     

稀土金属Tb催化制备GaN纳米棒(英文)

利用稀土金属Tb作为催化剂,通过氨化磁控溅射在Si(111)衬底上的Ga2O3/Tb薄膜制备出GaN纳米棒。X射线衍射和傅里叶红外吸收谱测试结果表明,制备的样品为六方结构的GaN。利用扫描电子显微镜、透射电子显微镜和高分辨透射电子显微镜对样品进行测试,结果显示样品为单晶结构的纳米棒,直径为80～200nm,长度达几十微米。最后简单地讨论了GaN纳米棒的生长机制。     

W18O49@Cu2O纳微米复合材料的制备及其光催化性能研究

本文首先用热蒸发方法制备得到了W₁₈O₄₉纳微米棒,然后经醋酸铜饱和溶液浸泡后再热处理的办法成功在W₁₈O₄₉纳微米棒表面负载Cu₂O制得得到了W₁₈O₄₉@Cu₂O纳微米复合材料;采用X-射线衍射仪、扫描电子显微镜、X-射线能谱分析及透射电子显微镜对样品进行分析表征;最后选用亚甲基蓝溶液作为目标降解物模拟污水处理测试材料的光催化性能。实验结果表明,W₁₈O₄₉纳微米棒在饱和醋酸铜溶液中浸泡时间越长,所得到的催化剂中Cu₂O的负载量越多,且所制备的W₁₈O₄₉@Cu₂O的纳微米复合材料相对于纯W₁₈O₄₉纳微米棒,其光催化效率得到了显著提高。     

Preparation of GaN Nanorods by Rare Earth Metal Tb Catalyst-Assisted Process

利用稀土金属Tb作为催化剂,通过氨化磁控溅射在Si(111)衬底上的Ga203/Tb薄膜制备出GaN纳米棒.X射线衍射和傅里叶红外吸收谱测试结果表明,制备的样品为六方结构的GaN.利用扫描电子显微镜、透射电子显微镜和高分辨透射电子显微镜对样品进行测试,结果显示样品为单晶结构的纳米棒,直径为80～200 nm,长度达几十微米.最后简单地讨论了GaN纳米棒的生长机制.     

氧化铋亚微米棒在水热条件下的可控生长研究(英文)

用水热法制备了单斜结构的氧化铋亚微米棒,而且通过控制硝酸铋的浓度和水热反应时间,能有效地控制氧化铋亚微米棒的直径和长径比。氧化铋亚微米棒的晶体结构、尺寸和形状用 X-射线衍射、扫描电子显微镜和透射电子显微镜进行了表征。研究发现:随着硝酸铋浓度的降低,氧化铋粒子的尺寸逐渐减小;随着反应时间的增加,氧化铋亚微米棒的直径和长度逐渐增加。此外,还讨论了氧化铋亚微米棒的形成机理。     

基于溶胶凝胶法水热合成WO_3纳米材料及气致变色应用（英文）

以钨粉和氧化钨溶胶干粉作为前驱体,通过水热合成以及溶胶凝胶法制备了纳米氧化钨。通过X射线衍射分析仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外分光光度计(FT-IR)以及拉曼光谱(Raman)对水热产物进行了表征和分析。XRD表征显示2种结构分别属于单斜和六角相的氧化钨.电镜表征显示水热产物为纳米短棒和纳米长棒结构。为进一步研究水热产物对氧化钨气致变色性能的影响,通过将溶胶与不同晶相纳米结构复合的方式制备出了同源WO3复合薄膜.通过紫外分光光度计测试其气致变色性能。结果表明:单斜相复合薄膜降低了氧化钨的首次致色时间,六角相的复合薄膜保持了很好的气致循环特性。     

水热法制备高定向掺铝氧化锌纳米棒阵列

为了制备高定向光电性能优异的掺铝氧化锌(ZAO)纳米棒阵列,采用溶胶-凝胶法在玻璃基片上制备掺铝氧化锌薄膜,以ZAO薄膜为种子层,通过控制掺铝量、稳定荆等工艺参数,采用水热法制备出了高定向ZAO纳米棒阵列.实验表明,铝掺杂量为2%,直径在50nm左右的ZAO纳米棒阵列薄膜具有最好的光致发光性能,表面活性剂可以促进ZAO纳米结构的棒状生长,形成高定向ZAO纳米棒阵列.     

氨化磁控溅射Ga2O3/BN薄膜制备GaN纳米棒

利用射频磁控溅射技术在Si(111)衬底上制备Ga2O3/BN薄膜,在氨气中退火合成了大量的一维GaN纳米棒.用X射线衍射(XRD)、选区电子衍射(SAED)、傅立叶红外透射谱(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和光致发光谱(PL)对样品的晶体结构、元素成分、形貌特征和光学特性进行了分析.结果表明GaN纳米棒为六方纤锌矿结构的单晶相,其直径在150 nm～400 nm左右,长度可达几十微米.室温下光致发光谱的测试发现了较强的372nm处的强紫外发光峰和420nm处的蓝色发光峰.     

氨化磁控溅射Ga2O3/BN薄膜制备GaN纳米棒

利用射频磁控溅射技术在Si(111)衬底上制备Ga2O3/BN薄膜,在氨气中退火合成了大量的一维GaN纳米棒.用X射线衍射(XRD)、选区电子衍射(SAED)、傅立叶红外透射谱(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和光致发光谱(PL)对样品的晶体结构、元素成分、形貌特征和光学特性进行了分析.结果表明:GaN纳米棒为六方纤锌矿结构的单晶相,其直径在150 nm～400 nm左右,长度可达几十微米.室温下光致发光谱的测试发现了较强的372nm处的强紫外发光峰和420nm处的蓝色发光峰.     

Comparison of different tungsten precursors for preparation of tungsten nanopowder by RF induction thermal plasma

Tungsten nanopowders were synthesized using three different precursors: commercial tungsten (W), tungsten trioxide (WO₃), and ammonium paratungstate (APT) by radio-frequency (RF) induction thermal plasma in the presence and absence of H₂. The crystalline structure, morphology, and particle size of the synthesized tungsten nanopowders were analyzed by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The W nanopowder obtained using APT precursor was found to be the most homogeneous and smallest nanoparticles and showed the largest α-W phase (stable) fraction, which is the preferred phase for tungsten because of its superior properties to those of the β-W phase (metastable).     

电冶熔铸WC/钢复合材料的显微缺陷

采用电冶熔铸工艺将废弃的WC钢结硬质合金制备成WC/钢复合材料, 研究了复合材料中显微缺陷的形貌及形成机理.结果表明: 电冶熔铸WC/钢复合材料的气孔及夹杂含量少, 可有效解决WC颗粒的偏析.X射线衍射、扫描电镜和透射电镜分析显示, WC颗粒和钢基体界面上发生了界面反应, 生成了高稳定性的Fe3W3C界面层.     

射频等离子体制备球形钨粉的研究

通过射频等离子体球化处理工艺,以不规则形状钨粉为原料,制备了球形钨粉,并研究了加料速率和粉末粒度对粉末球化率的影响。采用扫描电子显微镜、X射线衍射和激光粒度分析仪对球化处理前后粉末的形貌、物相和粒度分布进行了测试和分析。结果表明：粒度在5.5~26.5 μm范围的不规则形状钨粉,经等离子球化处理后得到表面光滑、分散性好、球化率可达100%的球形钨粉。球化处理后,粉末的粒度略微增大。随加料速率的增加,钨粉的球化率降低。随着钨粉球化率的提高,粉末的松装密度和流动性得到显著改善。松装密度由6.80 g/cm3 提高到11.5 g/cm3,粉末流动性由14.12 s/50 g提高为6.95 s/50 g     

Effect of trace tungsten on the microstructure of TiAl alloys containing Nb and B

New TiAl alloys, containing 45 at.% A1, 7 at.% Nb, x at.% W, and 0.15 at.% B （x = 0, 0.2, 0.4, and 0.7） were prepared by arc melting and drop casting consequently. Using optical microscopy, scanning electron microscopy （SEM）, and electron superprobe technologies, the effects of tungsten on the microstructural evolution of the TiA1 alloys, including the colony size and lamellar spacing, were analyzed. It was found that cellular structures and dendrites were formed in the as-cast TiA1 alloys, and heavy metals, such as niobium and tungsten, tend to segregate strongly at the interface of the cellular structures and dendrites. Trace tungsten can effectively impede the grain growth and narrow the interlamellar spacing. 0.4 at.% tungsten is more effective in refuting the microstructure of the TiAI alloys.     

Refinement process and mechanisms of tungsten powder by high energy ball milling

The grain refinement process and mechanisms of tungsten powder during ball milling are explored based on different ball milling time. From the results of scanning electron microscopy (SEM), the model for ball milling process is proposed to include four stages: welding stage, squeezing stage, fracturing stage and dynamic balance stage. Microstructure of tungsten powder examined by transmission electron microscopy (TEM) shows that the tungsten powder ball milled for 50 h has polycrystalline grains and most of them have long strip structure with high angle grain boundaries. Nanocrystalline tungsten powder with minimum grain size of 5 nm was obtained in the final stage of ball milling.     

Laser-assisted synthesis of carbon nanofibers: From arrays to thin films and coatings

Carbon nanofiber assemblies in the form of non-aligned films, arrays of vertically aligned nanofibers, aligned nanofiber mats and composite coatings were produced by laser-assisted catalytic chemical vapor deposition. A visible argon ion laser was used to thermally decompose pure ethylene over alumina supported nickel catalysts. Straight, vermicular, beaded, branched and coiled individual nanofibers were observed. The effects of the laser irradiation time on individual nanofiber characteristics, thus on overall nanofiber assembly characteristics were investigated. The arrays, nanostructured films and coatings were examined by scanning electron microscopy. The individual nanofibers were examined by transmission electron microscopy. Nanofiber texture and nanotexture were assessed by lattice fringe analysis of high resolution transmission electron microscopy images. The observed variation in the interfringe distance along the nanofiber wall suggests a pulsed growth mode. This growth mode and the nanofiber shaping mechanism are discussed. Recommendations on how to control nanofiber characteristics such as shape and internal structure are provided.     

Effect of process parameters on induction plasma reactive deposition of tungsten carbide from tungsten metal powder

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钨含量对高铬铸铁共晶组织及力学性能的影响

通过扫描电镜观察、Leica图像分析以及力学性能检测,探讨了钨含量从(0～4.11)wt%变化对高铬铸铁(27Cr)铸态共晶凝固组织和力学性能的影响。结果表明,当W含量在(0～2.92)wt%之间,随着W的增加,凝固组织共晶团尺寸逐渐减小,试样的冲击韧性随之改善,W在2.92wt%时共晶团尺寸最小,且碳化物分布均匀,对应的冲击韧度值为11 J.cm-2;当W含量从2.92wt%提高到4.11wt%时,共晶团尺寸增大,冲击韧度值由11 J.cm-2降低到9 J.cm-2。     

W-1%La2O3合金的显微组织分析

通过X射线衍射仪、光学显微镜、扫描电镜、透射电镜对聚变堆面向等离子体候选材料W-1%La2O3合金的显微组织进行了研究。结果表明:与纯钨相比,添加了1%La2O3的钨合金组织致密,孔隙与晶界裂缝消失,大量颗粒弥散在钨合金基体上。进一步的化学成分分析并结合电子衍射花样发现,在这些颗粒中不仅存在La2O3以及钨的氧化物,还存在一种镧的钨酸盐La2(WO4)3及非晶态颗粒。同时讨论了W-1%La2O3合金的韧性和存在颗粒的可能形成过程。     

Induction plasma spheroidization of tungsten and molybdenum powders

The melting, evaporation and oxidation behaviors as well as the solidification phenomena of tungsten and molybdenum in induction plasma were studied. Scanning electron microscopy was used to examine the morphology and the cross section of plasma-processed powders. X-ray diffraction was used to analyze the oxides formed on the particle surface of these two metals. The influence of spray chamber pressure on the spheroidization and oxidation phenomena was discussed. The results show that fewer Mo particles than W particles are spheroidized at the same powder feed rate under the same plasma spray condition although molybdenum has a lower melting point. A small fraction of tungsten is evaporized and condensed either on the surface of tungsten particles nearby or on the wall of spray chamber. Tungsten oxides were found in tungsten powder processed under soft vacuum condition. Extremely large grains form inside some spheroidized particles of tungsten powder.