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G C Hadjipanayis - One of the best experts on this subject based on the ideXlab platform.

  • influence of octanoic acid on smco5 nanoflakes prepared by surfactant assisted high energy Ball Milling
    Journal of Alloys and Compounds, 2010
    Co-Authors: Baozhi Cui, Liyun Zheng, Nilay G Akdogan, G C Hadjipanayis
    Abstract:

    Abstract High-Energy Ball Milling (HEBM) of magnetically hard SmCo 5 was conducted in heptane with octanoic acid as the surfactant. The effects of octanoic acid on the morphology and magnetic properties of the powders were investigated by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry. The results show an interesting unexpected fact that the SmCo 5 powders processed by octanoic acid-assisted HEBM were in form of nanoflakes with aspect-ratio of 10 2 –10 3 without the presence of nanoparticles. The thickness of nanoflakes decreases with increasing Milling time. X-ray diffraction patterns did not show the sign of oxidation and the diffraction peaks of SmCo 5 were getting broader with the increase of Milling time. The nanoflakes were magnetically anisotropic and had a higher coercivity than the micro-particles prepared by HEBM without surfactant. The coercivity of SmCo 5 increased initially with the Milling time and then it decreased after reaching the maximum value of 15.2 kOe. High-resolution transmission electron microscopy image showed that the SmCo 5 nanoflakes are nanocrystalline with an average crystallite size approximately 12 nm.

  • anisotropic smco5 nanoflakes by surfactant assisted high energy Ball Milling
    Journal of Applied Physics, 2010
    Co-Authors: Baozhi Cui, A M Gabay, M Marinescu, J F Liu, G C Hadjipanayis
    Abstract:

    Crystallographically anisotropic SmCo5 nanoflakes were fabricated directly by one-step surfactant-assisted high energy Ball Milling (HEBM) of Sm17Co83 ingot powders for 5 h in heptane and oleic acid (OA) without preprocessing or further annealing. The SmCo5 nanoflakes have a strong [001] out-of-plane texture. The thickness of nanoflakes is in the range of 8–80 nm while their length is 0.5–8 μm. The surfactant OA plays an important role in the formation of SmCo5 nanoflakes. HEBM of SmCo5 ingots in heptane without OA resulted in the formation of magnetically isotropic more or less equiaxed SmCo5 particles with a size of 2–30 μm. Closely packed “kebablike” SmCo5 nanoflakes were formed by HEBM in heptane with 15 wt % OA. HEBM in 150 wt % OA led to well-separated nanoflakes instead of the closely packed kebablike nanostructure. This resulted in the enhanced [001] out-of-plane texture. In-plane transmission electron microscope examination showed that the SmCo5 nanoflakes were composed of grains with sizes in th...

Ahmed Abuoqail - One of the best experts on this subject based on the ideXlab platform.

  • effect of high energy Ball Milling on strengthening of cu zro2 nanocomposites
    Ceramics International, 2019
    Co-Authors: Ahmed Abuoqail, A Wagih, A Fathy, Omayma A Elkady, A M Kabeel
    Abstract:

    Abstract In this paper, copper matrix nanocomposites reinforced by 5 and 10 wt% ZrO2 particles were produced by mechanical Milling technique at different Milling times. The produced nanocomposite powders were investigated by X-ray diffraction technique and transmission electron microscopy. The effect of high energy Ball Milling on the morphology, microstructure and microhardness of the produced composites has been investigated. After that cold compaction was applied to the prepared powders under a pressure of 700 MPa and sintered at 950 °C for 2 h in hydrogen atmosphere. The results showed that increasing Milling time improves microhardness of the prepared nanocomposites. The microhardness of Cu-10%ZrO2 after 20 h Milling is 3.76 times larger than pure Cu. This improvement is attributed firstly to the presence of ZrO2 nanoparticles in addition to the improvement coming from the grain refinement and crystallite size reduction occurred due to mechanical alloying. So, in spite of the crystallite size of Cu-10%ZrO2 nanocomposite is reduced to 10.75 nm compared to 105.5 nm for pure Cu, the presence of ZrO2 nanoparticles plays a major role on mechanical properties improvement.

  • effect of zro2 content on properties of cu zro2 nanocomposites synthesized by optimized high energy Ball Milling
    Ceramics International, 2019
    Co-Authors: A Fathy, A Wagih, Ahmed Abuoqail
    Abstract:

    Abstract In this paper, copper matrix nanocomposites reinforced by 5, 10 and 15 wt% ZrO2 particles were produced using high energy Ball Milling technique with different Milling time. The optimum Milling time is predicted analytically and validated experimentally. The effect of ZrO2 content on the morphology, microstructure, microhardness, compressive, electrical and wear properties of Cu-ZrO2 nanocomposites has been investigated. The results revealed that the optimum Milling time to produce Cu-ZrO2 nanocomposite with homogenous distribution of reinforcement is 15 h. The compressive strength, the microhardness and wear rate of the Cu-15%ZrO2 nanocomposites are improved by 58.2%, 288% and 19.3%, respectively, compared to pure copper. However, density and electrical conductivity are negatively affected by increasing ZrO2 content. The improvement in the mechanical and wear properties comes from the large reduction of the crystallite size by increasing ZrO2, reaching 32.5, 15.2 and 11.1 nm for samples containing, 5, 10 and 15 wt% ZrO2. Moreover, the reduction in the particle size due to mechanical Milling plays a critical role in the improvement of these properties.

Jie Lian - One of the best experts on this subject based on the ideXlab platform.

  • fabrication of lanthanum doped thorium dioxide by high energy Ball Milling and spark plasma sintering
    Journal of Nuclear Materials, 2017
    Co-Authors: Spencer M Scott, Tiankai Yao, Guoqing Xin, Weiguang Zhu, Jie Lian
    Abstract:

    Abstract Abstract High-Energy Ball Milling was used to synthesize Th1-xLaxO2-0.5x (x = 0.09, 0.23) solid solutions, as well as improve the sinterability of ThO2 powders. Dense La-doped ThO2 pellets with theoretical density above 94% were consolidated by spark plasma sintering at temperatures above 1400 °C for 20 min, and the densification behavior and the non-equilibrium effects on phase and structure were investigated. A lattice contraction of the SPS-densified pellets occurred with increasing Ball Milling duration, and a secondary phase with increased La-content was observed in La-doped pellets. A dependence on the La-content and sintering duration for the onset of localized phase segregation has been proposed. The effects of High-Energy Ball Milling, La-content, and phase formation on the thermal diffusivity were also studied for La-doped ThO2 pellets by laser flash measurement. Increasing La-content and high energy Ball Milling time decreases thermal diffusivity; while the sintering peak temperature and holding time beyond 1600 °C dramatically altered the temperature dependence of the thermal diffusivity beyond 600 °C.

  • facile low temperature solid state synthesis of iodoapatite by high energy Ball Milling
    RSC Advances, 2014
    Co-Authors: Fengyuan Lu, Spencer M Scott, Jinling Xu, Jingxian Wang, Zhili Dong, Rodney C Ewing, Jie Lian
    Abstract:

    The apatite structure-type has been proposed as a potential waste form for the immobilization of long-lived fission products, such as I-129; however, it is difficult to synthesize iodoapatite without significant iodine loss due to its high volatility. In this study, we report a facile low temperature (∼50 °C) solid-state method for successfully synthesizing lead-vanadate iodoapatite by High-Energy Ball Milling (HEBM) of constituent compounds: PbI2, PbO and V2O5. As-milled iodoapatite is in the form of an amorphous matrix embedded with nanocrystals and can be readily crystallized by subsequent thermal annealing at a low temperature of 200 °C with minimal iodine loss. Rietveld refinement of the X-ray diffraction patterns indicates that the thermally-annealed iodoapatite is iodine deficient with an iodine concentration of ∼4.2 at%. Thermal gravimetric analysis (TGA) indicates that low temperature annealing greatly improves the thermal stability and iodine confinement. This novel approach, using HEBM and thermal annealing, is a very promising method for synthesizing advanced materials that can confine highly volatile radionuclides, such as I-129, which pose significant challenges for the successful disposal of high-level nuclear waste.

  • zno graphene nanocomposite fabricated by high energy Ball Milling with greatly enhanced lithium storage capability
    Electrochemistry Communications, 2013
    Co-Authors: Dali Shao, Xiang Sun, Hongtao Sun, Gongkai Wang, Shayla Sawyer, Hong Qiu, Jie Lian
    Abstract:

    Abstract The ZnO/graphene nanocomposite was synthesized by high energy Ball Milling and evaluated as an anode material for lithium-ion batteries. EDX elemental mapping indicated that graphene was dispersed homogeneously in the ZnO matrix. The nanocomposite exhibits an initial reversible capacity of 783 mAh/g and maintained a capacity of 610 mAh/g after 500 cycles at 100 mA/g. Moreover, it shows excellent rate capability and cycling stability even at 10,000 mA/g, which can be attributed to the unique structure and the synergistic effect between the nanosized ZnO and graphene.

Alexander S Mukasyan - One of the best experts on this subject based on the ideXlab platform.

  • bulk cu cr nanocomposites by high energy Ball Milling and spark plasma sintering
    Journal of Alloys and Compounds, 2014
    Co-Authors: N F Shkodich, Alexander S Rogachev, S G Vadchenko, D O Moskovskikh, N V Sachkova, Sergei Rouvimov, Alexander S Mukasyan
    Abstract:

    Abstract A set of nanocomposite Cu–Cr powders with the grain size of these immiscible metals below 5 nm were prepared by High-Energy Ball Milling. The powders were then consolidated by short-term (5 min) spark plasma sintering at 700–900 °C under pressure (50 MPa) to obtain essentially pore-free pseudo-alloys. The grain sizes in the produced bulk materials remained within the ranges 5–60 nm for Cr-based phase and 200–300 nm for Cu-based matrix. These nanocomposites have a Vickers microhardness up to 3.9 GPa and a specific electrical resistivity in the range 6–9.6 μΩ cm, which make them promising candidates for the application in high-voltage circuit breakers.

Huaiwu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Fabrication of nanopowders by high energy Ball Milling and low temperature sintering of Mg2SiO4 microwave dielectrics
    Journal of Alloys and Compounds, 2012
    Co-Authors: Lin Cheng, Wencheng Niu, Guoguang Yao, Xiaogang Zhao, Peng Liu, Qian Liu, Xiaoming Chen, Cheng Liu, Huaiwu Zhang
    Abstract:

    Mg2SiO4 nanopowders were prepared from MgO and SiO2 mixtures by using a high energy Ball Milling method, combined with subsequent calcination at low temperatures. After Milling for 30h, pure phase Mg2SiO4 nanopowders with an average grain size of 147.4nm were obtained at 850°C, 300°C lower than that required by a conventional solid state reaction process. Mg2SiO4 ceramics sintered at a low temperature of 1075°C showed almost full density and excellent microwave dielectric properties (ɛr=7.2, Q×f=193,800GHz, τf=−58ppm/°C).

  • low temperature synthesis of mg4nb2o9 nanopowders by high energy Ball Milling method
    Journal of Alloys and Compounds, 2010
    Co-Authors: Zhifen Fu, Xiaoming Chen, Huaiwu Zhang
    Abstract:

    Abstract The effects of High-Energy Ball Milling and subsequent calcinations on the mixture of MgO and Nb2O5 were investigated. It was found that the formation temperature of the single-phase Mg4Nb2O9 powders had a consanguineous connection with Milling time, calcinations temperature and dwell time. With increasing Milling time, calcinations temperature and dwell time, the qualitative concentration of Mg4Nb2O9 phase increased. Pure Mg4Nb2O9 nanopowders with average particle size of 72.5 nm were primary synthesized at 900 °C for 3 h from 60 h powders. The Mg4Nb2O9 ceramics with almost full density and an excellent microwave dielectric properties (ɛr = 12.6, Q × f = 175,810 GHz) were obtained after annealing at 1200 °C from the milled 60 h powders.