scholarly journals Exothermic synthesis and consolidation of single-phase ultra-high temperature composite Ta4ZrC5

2019 ◽  
Vol 488 (2) ◽  
pp. 153-156
Author(s):  
V. A. Shcherbakov ◽  
A. N. Gryadunov ◽  
S. G. Vadchenko ◽  
M. I. Alymov
Keyword(s):  
Particle Size ◽  
Phase Composition ◽  
High Temperature ◽  
Ceramic Composite ◽  
Single Phase ◽  
Average Particle Size ◽  
Average Particle ◽  
Refractory Compounds ◽  
Isostatic Compression ◽  
Ultra High Temperature

The paper presents the experimental results of possibility obtaining ultra-high temperature composite Ta4ZrC5 using a single-stage method. The method is based on the use of exothermic synthesis of refractory compounds by electro-thermal explosion (ETE) and their consolidation under conditions of quasi-isostatic compression. The effect of mechanical activation of the reaction mixture of tantalum, zirconium and carbon powders on the formation of the phase composition of the ceramic composite Ta4ZrC5 was studied. The conditions for obtaining a single-phase ultra-high temperature composites had were determined. The composites were prepared with the average particle size of 1-2 µm and a residual porosity of 8-10%.

scholarly journals 3D Online Submicron Scale Observation of Mixed Metal Powder's Microstructure Evolution in High Temperature and Microwave Compound Fields

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Dan Kang ◽  
Feng Xu ◽  
Xiao-fang Hu ◽  
Bo Dong ◽  
Yu Xiao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
High Temperature ◽  
Microstructure Evolution ◽  
Diffusion Mechanism ◽  
Average Particle Size ◽  
Average Particle ◽  
Reconstruction Method ◽  
Neck Size ◽  
Submicron Scale

In order to study the influence on the mechanical properties caused by microstructure evolution of metal powder in extreme environment, 3D real-time observation of the microstructure evolution of Al-Ti mixed powder in high temperature and microwave compound fields was realized by using synchrotron radiation computerized topography (SR-CT) technique; the spatial resolution was enhanced to 0.37 μm/pixel through the designed equipment and the introduction of excellent reconstruction method for the first time. The process of microstructure evolution during sintering was clearly distinguished from 2D and 3D reconstructed images. Typical sintering parameters such as sintering neck size, porosity, and particle size of the sample were presented for quantitative analysis of the influence on the mechanical properties and the sintering kinetics during microwave sintering. The neck size-time curve was obtained and the neck growth exponent was 7.3, which indicated that surface diffusion was the main diffusion mechanism; the reason was the eddy current loss induced by the external microwave fields providing an additional driving force for mass diffusion on the particle surface. From the reconstructed images and the curve of porosity and average particle size versus temperature, it was believed that the presence of liquid phase aluminum accelerated the densification and particle growth.

scholarly journals Crystal structure, optical and magnetic properties of PrFeO3 nanoparticles prepared by modified co-precipitation method

2020 ◽  
Vol 14 (4) ◽  
pp. 355-361
Author(s):  
Anh Nguyen ◽  
Ngoc Nguyen ◽  
Irina Mittova ◽  
Nikolai Perov ◽  
Valentina Mittova ◽  
...  
Keyword(s):  
Particle Size ◽  
Single Phase ◽  
Average Particle Size ◽  
Precipitation Method ◽  
Average Particle ◽  
Strong Adsorption ◽  
Different Temperatures ◽  
Paramagnetic Materials ◽  
Co Precipitation ◽  
Potential Use

In this work, PrFeO3 nanoparticles were synthesized by modified co-precipitation method and annealed at different temperatures up to 850?C. The annealed PrFeO3 nanoparticles have single phase orthorhombic structure and the average particle size of 25-30 nm. Due to the very small particle size the prepared PrFeO3 nanoparticles are capable of being used as photocatalyst materials thanks to their strong adsorption bands at 230-400 nm and 400-800 nm observed from the UV-Vis spectra. Additionally, the PrFeO3 nanoparticles are paramagnetic materials with Hc ~ 10Oe and Mr ~ 0. These findings demonstrate their potential use not only as photocatalysts, but also as magnetic materials.

Research on the Preparation of Cu-Ni-Al Prealloyed Powders

2013 ◽  
Vol 303-306 ◽  
pp. 2490-2494 ◽  
Author(s):  
Peng Lei ◽  
Jian Chen ◽  
Wei Li ◽  
Yan Jie Ren ◽  
Wei Qiu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Particle Size ◽  
Phase Composition ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Spherical Particle ◽  
Average Particle Size ◽  
Average Particle ◽  
Scanning Electron

The method of preparation of Cu-Ni-Al prealloyed powders were studied in this paper. Cu, Ni, Al were smelted at 1500°C and N2 was chosen as atomizing media to produce the Cu-Ni-Al prealloyed powders. The morphology and particle size distribution of Cu-Ni-Al prealloyed powders were analysis with Scanning electron microscopy; the phase composition of Cu-Ni-Al prealloyed powders were analysis XRD. The results show that the morphology of Cu-Ni-Al prealloyed powders are almost nearly spherical, particle size distribution is very uniform and the average particle size is 39μm. The powders are composed of Cu and AlNi phase.

Preparation of La1-xSrxMnO3 Materials by High Temperature Solid Phase Method

2012 ◽  
Vol 562-564 ◽  
pp. 482-485
Author(s):  
Zeng Gang Li ◽  
Zeng Yong Chu ◽  
Yong Jiang Zhou ◽  
Hai Feng Cheng
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
High Temperature ◽  
Solid Phase ◽  
Average Particle Size ◽  
Phase Method ◽  
Average Particle ◽  
Structure And Morphology ◽  
Solid Phase Method ◽  
Perovskite Type

La1-xSrxMnO3 (LSMO) (x=0.1, 0.2, 0.3, 0.4)powders were synthesized by high temperature solid phase method, and the crystal structure and morphology were characterized by XRD and SEM. Results indicated that the pure perovskite type LSMO could be obtained after sintered at the temperature of 1000°C for 6h. The average particle size of the powders decreases with the increasing concentration of Strontium.

Self-Propagating High-Temperature Synthesis of TiB2-Ti(C, N) Cermets Composite Powder

2012 ◽  
Vol 468-471 ◽  
pp. 1247-1250 ◽  
Author(s):  
Fang Yang ◽  
Zhi Meng Guo ◽  
Jun Jie Hao ◽  
Yong Liang Shi
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Ni Addition ◽  
Brittle Phase

The ultra-fine TiB2-Ti(C, N) composite powders were prepared by self-propagating high-temperature synthesis (SHS) with Ti, BN and C powders as its starting materials. The morphology of the products was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed the composite powders were consisted of the mainly phases Ti(C, N), TiB2 and a small amount of TiN phase. With the Ni addition, the brittle phase Ni3B was appeared. SEM results revealed that the composite powders had a uniform particle size, a round grain-shaped structure and a narrow size distribution and the average particle size of which is less than 1μm.

Synthesis and Properties of Superparamagnetic Fe3O4 Nanoparticles by Co-Precipitation Process

2013 ◽  
Vol 377 ◽  
pp. 173-179 ◽  
Author(s):  
Chan Yin ◽  
Xiao Yi Wei ◽  
Ji Hua Li ◽  
Fei Wang
Keyword(s):  
Particle Size ◽  
Saturation Magnetization ◽  
Single Phase ◽  
Average Particle Size ◽  
Particle Surface ◽  
Anhydrous Ethanol ◽  
Precipitation Process ◽  
Average Particle ◽  
Agglomeration Of Nanoparticles ◽  
Co Precipitation

Superparamagnetic Fe3O4nanoparticle with single phase has been synthesized successfully by a co-precipitation process. On the other hand, the effect of additive anhydrous ethanol in synthesis procedure was investigated for the magnetic properties of nanoparticles in this paper. The structure properties of synthetic Fe3O4particle were measured through XRD, FT-IR and TG-DSC devices. The characteristic peaks of Fe3O4have been observed to testify Fe3O4with single phase. The particle size and shape were observed by SEM and TEM measurements. The addition of anhydrous ethanol could enhance the dispersion of Fe3O4nanoparticles and restrain the agglomeration of nanoparticles. Therefore, the average particle size was about 18.2 nm, smaller than that of Fe3O4particles prepared without anhydrous ethanol of 24.3 nm. Correspondingly, the saturation magnetization (Ms) of Fe3O4prepared with and without anhydrous ethanol was determined to be 53.28 emu/g and 65.28 emu/g, respectively, lower than bulk magnetite particles of 90 emu/g. That is because, synthetic Fe3O4with smaller particle size obtains the higher surface curvature, which could enhance the disordered crystal orientation on the particle surface, so the saturation magnetization was decreased.

scholarly journals Preparation and Evaluation of Sunflower Oil Nanoemulsion As a Sunscreen

2019 ◽  
Vol 7 (22) ◽  
pp. 3757-3761
Author(s):  
Anayanti Arianto ◽  
Cindy Cindy
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Sunflower Oil ◽  
Room Temperature ◽  
Ph Value ◽  
Average Particle Size ◽  
Tween 80 ◽  
Average Particle ◽  
Spontaneous Emulsification

BACKGROUND: There are a lot of different types of sunscreen products (oils, sticks, gels, creams, lotions) which can be found on the world's market. Sunscreen product that contains active chemical ingredients sometimes has harmful effects on the skin. Sunflower oil contains vitamin E and acts as a natural sunscreen which can absorb UVB light. The average droplet size of nanoemulsion is between 100 and 500 nm and do not show the problems of stability (creaming, flocculation, coalescence, and sedimentation), which are commonly associated with macroemulsions. AIM: The aim of this study was to prepare and evaluate the sunflower oil nanoemulsion as a sunscreen. METHODS: Sunflower oil nanoemulsions were prepared by spontaneous emulsification method with 3 formulas F1 (Tween 80 38%, sorbitol 22%), F2 (Tween 80 36%, sorbitol 24%), F3 (Tween 80 34%, sorbitol 26%) and 5% sunflower oil as a sunscreen substance. The nanoemulsions were evaluated for particle size, physical stability in room temperature (25 ± 2°C), low temperature (4 ± 2°C) and high temperature (40 ± 2°C) during experiment for 12 weeks of storage, centrifugation at 3750 rpm for 5 hours, viscosity, pH, freeze-thaw test and sun protection value (SPF) value by in vitro. RESULTS: The results of nanoemulsion evaluation showed that nanoemulsion formula F1 had the smallest average particle size of 124.47 nm with yellowish colour, clear, transparent, pH value (6.5 ± 0.1), viscosity value (225 ± 25 cP), did not show any separation or creaming in the centrifugation, and stable during experiment for 12 weeks of storage at room temperature, low temperature and high temperature. The SPF value of all nanoemulsion preparations was higher than that of the emulsion. CONCLUSION: The preparation of the sunflower oil nanoemulsion with a ratio of Tween 80 and sorbitol (38: 22) produces a stable nanoemulsion during the experiment for 12 weeks storage at the room, low and high temperature. The nanoemulsion preparation has higher SPF values compared to the emulsion. This nanoemulsion formulation could be considered more effective in sunscreen cosmetic use compare to the emulsion.

scholarly journals Influence of Mn2+ Concentration and UV Irradiation Time on the Luminescence Properties of Mn-doped ZnS Nanocrystals

2009 ◽  
Vol 19 (1) ◽  
pp. 33-38
Author(s):  
Tran Minh Thi
Keyword(s):  
Particle Size ◽  
Uv Irradiation ◽  
Single Phase ◽  
Irradiation Time ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
Wet Chemical ◽  
Mn Doped

ZnS:Mn were prepared by wet chemical method with Mn doping concentration from 0 at% to 12 at%. The structure and particle size of the obtained powders were measured by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and shown that all samples are single phase with sphalerite crystal structure and average particle size of about 5 - 7 nm. The dependence of Mn2+ ions doped concentration, and UV irradiation time on the luminescent intensity of ZnS:Mn nanocrystals was discussed.

CONTROL OF PARTICLE SIZE AND MORPHOLOGY OF COBALT-FERRITE NANOPARTICLES BY SALT-MATRIX DURING ANNEALING

2012 ◽  
Vol 05 ◽  
pp. 177-181
Author(s):  
A. AZIZI ◽  
S.K. SADRNEZHAAD ◽  
M. MOSTAFAVI
Keyword(s):  
Particle Size ◽  
Single Phase ◽  
Cobalt Ferrite ◽  
Average Particle Size ◽  
Average Particle ◽  
Mechanically Alloyed ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Full Annealing ◽  
Salt Matrix

Salt-matrix annealing of mechanically alloyed Co -ferrite nanopowder was used to modify its particle size and morphology. Efficiency improvement due to suppression of sintering and growth resulted in reduction of average particle size from ~100nm for salt-less to ~40nm for salt-full annealing procedure. Nanosized single-phase cobalt-ferrite particles were observed after 2h annealing at 750°C in the samples milled for 20 hours both with and without NaCl . NaCl:CoFe 2 O 4 ratio of 10:1 resulted in cabbage-like clusters containing particles smaller than ~50 nm.

scholarly journals Synthesis of Metal Matrix Composites Based on CrxNiy-TiN for Additive Technology

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5914
Author(s):  
Alexey Matveev ◽  
Vladimir Promakhov ◽  
Nikita Schultz ◽  
Alexander Vorozhtsov
Keyword(s):  
Particle Size ◽  
Phase Composition ◽  
Composite Materials ◽  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Metal Matrix ◽  
Average Particle Size ◽  
Additive Technologies ◽  
Average Particle ◽  
Direct Laser

The novelty of this work consists of obtaining original fundamental data on the laws of synthesis of new metal matrix composite materials for additive technologies. CrN + TiNi composites were obtained using the method of self-propagating high-temperature synthesis. In this work, analysis of the parameters of the synthesis of composite materials as well as their structure and phase composition were carried out. A scheme for the formation of a composite structure is established; it is shown that the phase composition is represented by 54.6 wt.% CrN and 45.4 wt.% TiNi. It was shown that composites based on the system are suitable for machines that make use of direct laser deposition to grow layers of materials. Sample structure and phase parameters were studied. It is shown that titanium nitride particles are uniformly distributed in the CrNi intermetallic matrix, the TiN particle size ranges from 0.3 to 9 μm and the average particle size is 2.8 μm. The results obtained indicate the possibility of synthesizing promising metal matrix composite materials for additive technologies. Such materials may have increased hardness, operating temperature and strength.

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