Characteristics of Fe powders prepared by spray pyrolysis from a spray solution with ethylene glycol as the source material of heat pellet

Fe powders as the heat pellet material for thermal batteries are prepared from iron oxide powders obtained by spray pyrolysis from a spray solution of iron nitrate with ethylene glycol. The iron oxide powders with hollow and thin wall structure produce Fe powders with elongated structure and fine primary particle size at a low reducing temperature of 615 °C. The mean size of the primary Fe powders with elongated structure decreases with increasing concentration of ethylene glycol dissolved into the spray solution. The heat pellets prepared from the fine-size Fe powders with elongated structure have good ignition sensitivities below 1 watt. The heat pellets formed from the Fe powders obtained from the spray solution with 0.5 M EG have an extremely high burn rate of 26 cms^?1.     

Effects of precursors of glass material on the characteristics of silver-glass composite powders prepared by spray pyrolysis

The characteristics of silver-glass composite powders directly prepared by spray pyrolysis from spray solutions with different precursor types of Pb, Si and Ti components were investigated. The composite powders had spherical shape and submicron size irrespective of precursor types of glass material and glass content of the powders. The silver conducting films formed from the composite powders had dense structures irrespective of precursor types of glass material and glass content of the powders. The silver conducting film formed from the composite powders obtained from the spray solution with fumed titania as the source material of the Ti component had the lowest sheet resistance of 2.8 mΩ/sq. The sheet resistances of the silver conducting films changed from 2.8 mΩ/sq to 3.7 mΩ/sq according to the glass content of the composite powders at a firing temperature of 700 °C.     

Nano-sized hydroxyapatite powders prepared by flame spray pyrolysis

Pure and doped CaMnO₃ were synthesized by applying modified glycine/nitrate procedure. The detailed structural characterization of prepared nanometric size powders, their properties, as well as the results on studying sintering and microstructure of the sintered bodies are given. Since the data on additive influence on densification of CaMnO₃ during sintering are difficult to find in the literature, their role in densification is discussed. It was found that increasing Y concentration enhanced densification during sintering, and in addition, suppressed grain growth process. The results of the electrical conductivity measurements as a function of dopant concentration are also discussed.     

Characteristics of fine size Fe-Ni alloy powders directly prepared by spray pyrolysis

Fe-Ni alloy powders with composition of Fe_0.25Ni_0.75 were directly prepared by spray pyrolysis. The powders prepared at temperatures of 1200 and 1400 °C had peaks of pure Fe-Ni₃ alloy phase. The alloy powders with a spherical shape and dense structure were prepared at a temperature of 1400 °C by melting the powders. The composition ratio of Fe and Ni components in the alloy powders prepared at a temperature of 1400 °C coincided well with that of the spray solution. The mean sizes of the alloy powders changed from 0.20 to 0.74 μm when the concentrations of the spray solution changed from 0.02 to 1 M. The alloy powders prepared from the spray solution with a concentration of 0.5M had a maximum saturation magnetization and minimum coercivity values as 96.95 emu g^?1 and 34.67 Oe, respectively.     

Characteristics of nano-sized silver–glass composite powders prepared by flame spray pyrolysis

Nano-sized silver–glass composite powders were directly prepared by high-temperature flame spray pyrolysis applying ultrasonic spray generator. The silver–glass composite powders with various glass contents had nanometer size, spherical shape and non-aggregation characteristics. The mean size of the silver–glass composite powders was 56 nm. The nano-sized silver–glass composite powders had pure Ag crystal structures irrespective of adding amounts of glass. The silver conducting films formed from the nano-sized silver–glass composite powders had dense structures at firing temperatures between 400 and 500 °C. The silver conducting films formed from the nano-sized silver–glass composite powders had lower sheet resistivities than those formed from the nano-sized silver powders irrespective of the firing temperatures. The sheet resistivities of the silver conducting films formed from the nano-sized silver–glass composite powders with 1 wt% glass content were 53, 16 and 11 mΩ/sq at firing temperatures of 400, 450 and 500 °C, respectively.     

喷雾热分解法制备超细银粉及其形貌控制

采用超声雾化热分解装置,对喷雾热分解法制备超细银粉进行了系统研究。考察了炉子温度、硝酸银水溶液浓度、超声雾化装置功率、硝酸银溶液及载气流量等因素对产物粒子形貌、粒度分布的控制行为。研究结果证实,喷雾热分解制备微米级球形金属银粉技术具有广泛应用前景。     

Nanocrystalline LiMn2O4 thin film cathode material prepared by polymer spray pyrolysis method for Li-ion battery

Nanocrystalline cubic spinel lithium manganese oxide thin film was prepared by a polymer spray pyrolysis method using lithium acetate and manganese acetate precursor solution and polyethylene glycol-4000 as a polymeric binder. The substrate temperature was selected from the thermogravimetric analysis by finding the complete crystallization temperature of LiMn₂O₄ precursor sample. The deposited LiMn₂O₄ thin films were annealed at 450, 500 and 600 °C for 30 min. The thin film annealed at 600 °C was found to be the sufficient temperature to form high phase pure nanocrystalline LiMn₂O₄ thin film. The formation of cubic spinel thin film was confirmed by X-ray diffraction study. Scanning electron microscopy and atomic force microscopy analysis revealed that the thin film annealed at 600 °C was found to be nanocrystalline in nature and the surface of the films were uniform without any crack. The electrochemical charge/discharge studies of the prepared LiMn₂O₄ film was found to be better compared to the conventional spray pyrolysed thin film material.     

Microstructure characteristics of coating with amorphous phases prepared from Fe-based alloy powders by plasma spray

In this paper, alloy powders mixed with a molar ratio of Fe ： P ： C of 80 ： 13 ： 7 were sprayed on Q235 steel by plasma spray method to prepare coating with amorphous phases. The phase composition of the mixed alloy powders and prepared coating were characterized by X-ray diffraction （ XRD ）. The morphology and the composition cf the coating were analyzed by scanning eleetron microscopy （SEM） nnd energy dispersive apectroscopy （ EDS ）. In addition, the thermal stability ef the coating with amorphous phases was characterized by differential thermal analyzer （ DTA ）. Tile results showed that, usirtg mixed alloy powders with a molar ratio of Fe： P： C of 80：13：7, the coating containing certain amount of amorphous alloys was suceessathlly prepared through atmospheric plasma spray technique. In the coating, the main phases were determined to be Fe, FeP aad Fe2P. The crystallization of the coating started from about 461°. Tile coating was mechanically adhered to the substrate.     

Pb-free glass frits prepared by spray pyrolysis as inorganic binders of Al electrodes in Si solar cells

Pb-free glass frits prepared by spray pyrolysis for Al electrodes were of fine size, spherical morphology and dense structure. Their mean size and geometric standard deviation when prepared at 1,200 °C were 1.0 μm and 1.4, respectively. Their glass transition temperature (T_g) was 374 °C. An Al electrode formed from Al paste with glass frits had a dense structure and good adhesion to the Si substrate. It had a well-developed back-surface field layer of 17.5 μm thickness. Al electrodes formed from Al paste without glass frits had sheet resistances between 21 and 32 mΩ sq⁻¹ as the firing temperature changed from 600 to 900 °C. This compared with values from electrodes formed with frits that decreased from 20 to 7 mΩ sq⁻¹ over the same range of firing temperatures.     

Characterization of cobalt oxide thin films prepared by a facile spray pyrolysis technique using perfume atomizer

Cobalt oxide (Co₃O₄) thin films were prepared by a facile spray pyrolysis technique using perfume atomizer from aqueous solution of hydrated cobalt chloride salt (CoCl₂·6H₂O) as source of cobalt. The films were deposited onto the amorphous glass substrates kept at different temperatures (300-500 °C). The influences of molar concentration of the starting solution and substrate temperature on the structural, morphological and optical properties of (Co₃O₄) thin films were studied. It was found from X-ray diffraction (XRD) analysis that the films prepared with molar concentration greater than 0.025 M/L were polycrystalline spinel type cubic structure. The preferred orientation of the crystallites of these films changes gradually from (6 2 2) to (1 1 1) when the substrate temperature increases. By Raman spectroscopy, five Raman active modes characteristic of Co₃O₄ spinel type cubic structure were found and identified at 194, 484, 522, 620 and 691 cm⁻¹. The scanning electron microscopy (SEM) images showed micro porous structure with very fine grains less than 50 nm in diameter. These films exhibited also a transmittance value of about 70% in the visible and infra red range.     

Characteristics of BaO-B2O3-SiO2 nano glass powders prepared by flame spray pyrolysis as the sintering agent of BaTiO3 ceramics

Nanosized BaO-B₂O₃-SiO₂ glass powders are directly prepared by flame spray pyrolysis. The mean size of the BaO-B₂O₃-SiO₂ glass powders with amorphous phase and spherical shape is 30 nm. The effects of glass powders on the sintering characteristics of the BaTiO₃ pellet formed from the nanosized BaTiO₃ powders are investigated. The mean size and BET surface area of the BaTiO₃ powders prepared by spray pyrolysis are 110 nm and 9.1 m²/g. The BaTiO₃ pellet with glass additive has large grain size with several microns, dense structure and pure tetragonal crystal structure at a sintering temperature of 1000 °C. The XRD pattern of the pellet has distinct split of (2 0 0) and (0 0 2) peaks at 2θ ≈ 44.95°. The dielectric constant of the pellet without glass additive is 2180. However, the dielectric constants of the pellets with 1, 3, 5 and 7 wt% glass additive with respect to BaTiO₃ are 2496, 2514, 2700 and 2225, respectively.     

喷雾造粒制备SiC-AIN复合粉体特性及烧结性能

采用水基料浆与流态化喷雾造粒相结合制备SiC-AIN复合粉体,分析复合粉体的粉体特性、成形性能及烧结特性,探讨SiC-AIN复相陶瓷的增强增韧机制.结果表明:喷雾造粒后,复合粉体的流动特性显著提高,粒度级配合理;随着压强增加,坏体密度在40～80、80～160和160～220 MPa范围内呈现阶梯式增长,160 MPa以上成形后素坯均匀致密,无硬球颗粒存在;无压烧结SiC-AIN复相陶瓷具有优越的烧结性能和力学性能,这是由于AIN对SiC晶粒形成生长势垒,并反应生成2H型固溶体,从而细化晶粒,导致裂纹扩展产生了绕道与偏转效应,呈现晶粒撕裂与拨出现象,协同改善了复相陶瓷的强度及断裂韧性.     

Photoelectrochemical investigations of cadmium sulphide (CdS) thin film electrodes prepared by spray pyrolysis

Polycrystalline cadmium sulphide (CdS) thin films have been prepared by spraying a mixture of an equimolar aqueous solutions of cadmium chloride and thiourea on preheated fluorine doped tin oxide (FTO) coated glass substrates at different substrate temperatures. The cell configurations n-CdS/1 M (NaOH + Na₂S + S)/C were used for studying the capacitance-voltage (C-V) characteristics in dark, current-voltage (I-V) characteristics in dark and under illumination, photovoltaic power output and spectral response characteristics of the as deposited thin films. Photoelectrochemical study shows that as deposited CdS thin films exhibits n-type of conductivity. The spectral response characteristics of the films at room temperature show a prominent sharp peak at 500 nm leading to optical bandgap energy of 2.48 eV. It is found that fill factor and efficiency are maximum for photoelectrode deposited at 300 °C. This is due to low resistance; high flat band potential, maximum open circuit voltage as well as maximum short-circuit current. The measured values of efficiency (η) and fill factor (FF) are found to be 0.17% and 0.38 respectively for film deposited at 300 °C.     

喷射成形Al-Fe-V-Si系耐热铝合金的制备工艺和性能

采用喷射成形方法制备了不同成分的Al-Fe-V-Si耐热铝合金，对喷射成形工艺参数进行了优化，对沉积坯件的热挤压工艺进行了探索，对材料的组织进行了分析，并对不同成分材料的性能进行了比较。结果表明：当喷射成形工艺参数选择合理时，沉积坯件具有良好的成形性与致密度，在随后的热挤压过程中，通过较低的挤压比即可使材料达到全致密；沉积坯件热挤压温度的降低有利于使材料获得更高的力学性能；同时，通过对合金成分的优化，可以获得加工和使用性能更加优良的Al-Fe-V-Si耐热铝合金。     

Characteristics of ZnO-B2O3-SiO2-CaO glass frits prepared by spray pyrolysis as inorganic binder for Cu electrode

ZnO-B₂O₃-SiO₂-CaO glass frits were directly prepared by high temperature spray pyrolysis for use in Cu electrodes. The frits prepared at temperatures above 1400 °C were spherical, amorphous, of fine size and dense structure. The mean particle size and geometric standard deviation of the frits prepared at 1400 °C were 0.87 μm and 1.37, respectively. The temperatures of glass transition, crystallization and melting were 454, 534 and 800 °C, respectively. The glass layer fired at 800 °C had a dense structure due to the material's complete melting, despite some crystals being observed by SEM. A copper electrode formed from copper paste with glass frits had a dense structure when fired at 800 °C. The specific resistances of electrodes formed from copper paste with and without glass frits were 2.5 and 8.5 μΩ cm, respectively.     

液相沉淀-热还原纳米Fe包覆Mo粉末微结构特征

采用液相沉淀-热还原法制备纳米Fe包覆Mo合金粉末,研究还原过程中的晶粒组织及微结构并进行分析.结果表明:还原过程中,粉末晶粒平均晶粒尺寸随还原温度的升高而变小,微观应变在还原温度为600 ℃时最高,Mo晶粒先于Fe晶粒还原并长大至1 μm左右,Fe晶粒粒径最终保持为1.8 nm,并形成20 nm左右的薄层,沉积在Mo颗粒表面.     

Characterization of ultrafine La x Sr1−x MnO3 powder prepared by spray pyrolysis

The characterization of La _x Sr_1−x MnO₃ powders produced by spray pyrolysis using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observation, specific surface area (Brunauer-Emett-Teller), and particle size distribution measurements shows that the resultant large particles are loose agglomerates consisting of many small particles. However, the sintered tiny particles can form hard agglomerates, and the particle size increases remarkably. The structures of the powders before and after sintering were identified by x-ray diffraction (XRD). The study of the electrical property of the powder shows that the powder is a metallic conductor. In a reducing atmosphere, the powder can be decomposed. When the powder is cofired with yttria-stabilized zirconia 5% (YSZ) powder at 1200 °C for 5 h, no new phase is produced, and the powder remains a single provskite hexagonal-rhombohedral structure.     

Microstructures and properties of Ni based composite coatings prepared by plasma spray welding with mixed powders

The Ni based composite coatings have been obtained by using the plasma spray welding process and mixed powders (NiCrBSi + NiCr-Cr₃C₂ + WC). Their microstructures and properties were studied. The results showed that the coatings consist mainly of γ-Ni, WC, Cr₂₃C₆, Cr₇C₃, Ni₃Si, Cr₅B₃, CrB and FeNi₃ phases, and the Ni₃Si, Cr₅B₃, CrB and FeNi₃ phases mainly segregated between the carbide grains. The carbide contents in the coatings increased with increasing the mass fractions of NiCr-Cr₃C₂ and WC powders in the mixed powders, which results in enhancing the coating hardness. The abrasive wear resistance of the coatings depends on their hardness. The higher the coating hardness, the stronger the wear resistance is. When the mixed powder (15wt%WC + 30 wt% NiCr-Cr₃C₂ + 55wt%NiCrBSi) was used, the composite coating has higher hardness and more excellent wear resistance, and the coating hardness and weight loss after wear tests are 991 HV and 8.6 mg, respectively.     

Properties and structure of coatings from PG-SR powders prepared by a plasma method

In recent years, a plasma method for obtaining coatings with the use of a controlled electric arc instead of an uncontrolled welding arc has found wide application in various branches of industry. The Laboratory of Materials Science at the Institute of Coal of the Siberian Branch of the Russian Academy of Sciences is working on the possibility of using plasma strengthening coatings for increasing the wear resistance of parts of mining equipment. A whole spectrum of coated parts for hydraulic supports and the equipment of concentration plants with an increased service life and wear resistance has been suggested. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 26–28, August, 1997.     

AI-Li/SiCp composites and Ti-AI alloy powders and coatings prepared by a plasma spray atomization (PSA) technique

There has been increasing use of Al-Li alloys in the aerospace industry, due mainly to the low density and high elastic modulus of this material. However, the problem of low ductility and fracture toughness of this material has limited its present application to only weight- and stiffness-critical components. Development of Al-Li/ceramic composites is currently being investigated to enhance the service capabilities of this material. The Ti-Al alloy is also of interest to aerospace-type applications, engine components in particular, due to its attractive high-temperature properties. Preparation of fine powders by plasma melting of composite feedstock and coatings formed by plasma spraying was carried out to examine the effect of spray parameters on the microstructure and properties of these materials. Characterization of the powders and coatings was performed using the scanning electron microscope and image analyzer. Examination of the plasma-sprayed powders and coatings has shown that in the Al-Li/SiC composite there is melting of both materials to form a single composite particle. The SiC reinforcement was in the submicron range and contributed to additional strengthening of the composite body, which was formed by a cold isostatic press and consolidated by hot extrusion or hot forging processes. The plasma-sprayed Ti-Al powder showed four categories of microstructures: featureless, dendritic, cellular, and martensite-like.