scholarly journals Synthesis of Cu-CNTs nanocomposites via double pressing double sintering method

2018 ◽  
Vol 23 (4) ◽  
pp. 319-334 ◽  
Author(s):  
Marjan Darabi ◽  
Masoud Rajabi
Keyword(s):  
Electrical Conductivity ◽  
Ball Mill ◽  
Bending Strength ◽  
Sintering Process ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conventional Sintering ◽  
Cold Pressed ◽  
Sintering Method

In this research, copper (Cu)-carbon nanotubes (CNTs) nanocomposites were synthesized with different weight percentages of CNTs by double pressing double sintering (DPDS) method as well as conventional sintering method. A planetary ball mill was used to disperse CNTs in Cu matrix. The milled powders were first cold pressed to 450 MPa in a uniaxial stainless-steel die with cylindrical compacts (diameter: 12 mm and height: 5 mm). The effect of CNTs content and the DPDS method on the properties of the nanocomposites were investigated. The microstructure and phase analysis of Cu-CNTs nanocomposite samples were studied by FESEM and X-Ray Diffraction. The electrical conductivity of nanocomposites was measured and compared to both sintering methods. Mechanical properties of Cu-CNTs nanocomposites were characterized using bending strength and micro-hardness measurements. Enhancements of about 32% in bending strength, 31.6% in hardness and 19.5% in electrical conductivity of Cu-1 wt.% CNTs nanocomposite synthesized by DPDS method were observed as compared to Cu-1 wt.% CNTs nanocomposites fabricated under the similar condition by a conventional sintering process.

Laser Sintering of Greens Compacts of MoSi2

2006 ◽  
Vol 530-531 ◽  
pp. 364-368
Author(s):  
G. de Vasconcelos ◽  
R. Cesar Maia ◽  
Carlos Alberto Alves Cairo ◽  
R. Riva ◽  
N.A.S. Rodrigues ◽  
...  
Keyword(s):  
Cross Section ◽  
Laser Processing ◽  
Single Phase ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heating Source ◽  
Scanning Electron Microcopy ◽  
Conventional Sintering ◽  
Reduced Time

In this study, the results of the feasibility of sintering green compacts of metallic powder of MoSi2 by a CO2 laser beam as the heating source has been investigated. The main advantage of this technique is to promote a dense material in a reduced time when compared to the conventional sintering process. In order to sintering the MoSi2 powder, green compacts of 6mm of diameter and 1.6mm thickness were produced in a steel die in a uniaxial press at 100MPa and after, isostatic pressed at 350MPa. The micrograph of the samples exposed to the laser radiation performed by scanning electron microcopy (SEM) reveal the efficiency of the sintering process and the X-ray diffraction of the powders confirmed the presence of single phase after and before laser processing. The average microhardness of these compacts reached near to 700 Hv0.2 in the cross section to the laser irradiation, indicating the all sintering of the green compact.

Formation of Tricalcium Silicate Prepared by Electric and Microwave Sintering

2010 ◽  
Vol 148-149 ◽  
pp. 1119-1123
Author(s):  
Kai Ke ◽  
Bao Guo Ma ◽  
Xiao Liang Wang ◽  
Xiang Guo Li
Keyword(s):  
Heating Temperature ◽  
Microwave Sintering ◽  
Electric Heating ◽  
Tricalcium Silicate ◽  
Experimental Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conventional Sintering ◽  
Sintering Method

A microwave sintering method was used to prepare C3S from Ca(OH)2, SiO2 and MexOy. f-CaO assay, X-ray diffraction and SEM were used to characterize the sintered samples.The results indicated that ion oxides played a very important role in C3S formation in conventional sintering, the use of MexOy as an additive was so effective in promoting C3S formation. The experimental results showed that samples were heated at an electric heating temperature(1500°C) and then further sintered with microwave for 30~60 min, tricalcium silicate could be formed with kilogram step. The new burning technique can greatly increase the forming speed of tricalcium silicate, MnO2, CuO and Ni2O3 could enhance the microwave sintering.

scholarly journals Investigation of selenium compounds as targets for 76,77Br production using protons of energies up to 34 MeV

2017 ◽  
Vol 105 (10) ◽  
Author(s):  
H. Ebrahim Hassan ◽  
Khaled M. El-Azony ◽  
Ahmed Azzam ◽  
Syed M. Qaim
Keyword(s):  
Phase Composition ◽  
X Ray Diffraction ◽  
Selenium Compounds ◽  
X Ray ◽  
Conventional Sintering ◽  
Sintering Method ◽  
Separation Conditions

AbstractSelenium compounds of Zn, Sn and Cu were prepared using a conventional sintering method and the phase composition of each compound was investigated using X-ray diffraction. The compounds prepared were tested under variable irradiation and separation conditions for

Fabrication and Characterization of a Feldspar-Alumina for Dental Ceramic

2010 ◽  
Vol 160-162 ◽  
pp. 424-427
Author(s):  
Guang Lei Zhang ◽  
Guo Qiang Qin ◽  
Yuan Hua Zhang ◽  
Pu Cheng ◽  
Chang Tao Shao
Keyword(s):  
Sinter Temperature ◽  
Bending Strength ◽  
Dental Ceramics ◽  
Alumina Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fabrication And Characterization ◽  
Sintering Method ◽  
Scanning Electron

Feldspar-alumina dental ceramics were produced by impressed sintering method and characterized by X-ray diffraction and scanning electron microscope techniques. The machinability of the obtained alumina ceramics was evaluated by grinding capacity in the simulative grinding experiment. The results show that an appropriate amount of feldspar additive can reduce the sinter temperature and improve density, bending strength and machinability of alumina dental ceramics. Under 10 wt% feldspar and 1450 °C sinter temperature, the relative density and bending strength of ceramic reached 93.62% and 235MPa, respectively.

Fabrication of W-Cu/Lu2O3 Composites with High Strength and Electrical Conductivity Prepared by Electroless Plating and Powder Metallurgy

2016 ◽  
Vol 849 ◽  
pp. 825-830
Author(s):  
Ze Long Lu ◽  
Lai Ma Luo ◽  
Jun Zhang ◽  
Yong Qing Qin ◽  
Xin Min Huang ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Powder Metallurgy ◽  
Electroless Plating ◽  
Bending Strength ◽  
High Strength ◽  
National Standard ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Standard Value

W–Cu (0, 0.25, 0.75, 1.5, and 3 wt.%)/Lu2O3 composite materials were prepared through electroless plating with simplified pretreatment method and powder metallurgy. The phases and morphologies of the W–Cu/Lu2O3 composites were characterized by X-ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy. The relative density, microhardness, electrical conductivity, and bending strength of the sintered samples were examined. The experimental results show that W–Cu composites with uniform structures can be obtained with pretreated W using the simplified method, followed by electroless Cu plating. The microstructure and properties of the composites were significantly affected by the addition of Lu2O3 nanoparticles, resulting in high electrical conductivity and strength. The electrical conductivity of W–Cu/1.5 wt.% Lu2O3 composites reached 63.3%, which is higher than the national standard value of 50.71%. The bending strength of W–Cu/1.5 wt. % Lu2O3 reached 1306.7 MPa, which is 65.41% higher than the national standard. These results may be attributed to the uniform distribution of refined particles with Lu2O3 content increased to 1.5 wt. %.

STUDY ON ABNORMAL PHENOMENON ABOUT ENHANCED ELECTRICAL CONDUCTIVITY OF Bi1-xBaxFeO3 CERAMICS

2014 ◽  
Vol 28 (05) ◽  
pp. 1450009 ◽  
Author(s):  
H. J. WANG ◽  
S. Y. WANG ◽  
W. F. LIU ◽  
X. J. XI ◽  
FENG GUO ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Photoelectron Spectroscopy ◽  
Oxygen Vacancies ◽  
Solid Phase ◽  
Electrical Conductance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multiferroic Properties ◽  
Abnormal Phenomenon ◽  
Sintering Method

In order to investigate the effects of Ba doping BiFeO 3 on multiferroic properties, Bi 1-x Ba x FeO 3(0≤x≤1)( Ba x BFO ) ceramics were fabricated via rapid solid phase sintering method, and material's structures and electrical properties were investigated. The phase transitions from rhombohedral to pseudo-cubic (x = 10%) and then to tetragonal (x = 40%) were confirmed by X-ray diffraction investigation. Although the electrical conductivity of Ba x BFO (x = 10%, 20% and 30%) ceramics was low, which is a similar trend to previous reports, an abnormal enhancement of electrical conductance was observed in Ba x BFO (x = 1%, 3% and 5%) ceramics. Such as, the electrical conductivity of Ba 0.03 BFO is calculated to be ~106 Ω⋅ cm that is five orders of magnitude higher than that of the BiFeO 3. This has been discussed and ascribed to more percent of oxygen vacancies and Fe 2+ ions in Ba x BFO ceramics, as confirmed by X-ray photoelectron spectroscopy investigation.

scholarly journals The influence of compaction pressure on the density and electrical properties of cordierite-based ceramics

2015 ◽  
Vol 47 (1) ◽  
pp. 15-22 ◽  
Author(s):  
N. Obradovic ◽  
N. Djordjevic ◽  
A. Peles ◽  
S. Filipovic ◽  
M. Mitric ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ball Mill ◽  
Compaction Pressure ◽  
High Energy ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Air Atmosphere ◽  
High Energy Ball Mill ◽  
Energy Ball

Due to its characteristics, cordierite, 2MgO?2Al2O3?5SiO2, is a high-temperature ceramic material of a great scientific interest. Mechanical activation of the starting mixtures containing 5.00 mass% TiO2 was performed in a high-energy ball mill for 10 minutes. The compaction pressure varied from 0.5 to 6tcm-2 (49-588 MPa). The sintering process was performed at 1350?C for four hours in the air atmosphere. The phase composition of the activated and sintered samples was analyzed using X-ray diffraction. Scanning electron microscopy was used to analyze the microstructure of both compacted and sintered samples. The authors have investigated the influence of compaction pressure on the sintered samples and their electrical properties.

Li2ZnTi3O8 Microwave Dielectric Ceramics Prepared by the Reaction-Sintering Process

2015 ◽  
Vol 655 ◽  
pp. 164-167 ◽  
Author(s):  
Xu Sheng Hu ◽  
Guo Guang Yao ◽  
Xiu Lao Tian
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Reaction Sintering ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Pure Phase ◽  
Dielectric Ceramics ◽  
Sintering Method

Li2ZnTi3O8ceramics were prepared by reaction-sintering process (calcination free). The crystal phase and microstructure were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). A pure phase of Li2ZnTi3O8ceramics sintered at 1075 °C-1150 °C with cubic spinel structure was confirmed by XRD. The microwave dielectric properties (εr,Qxf) of Li2ZnTi3O8ceramics were strongly dependent on the densification and grain size. The τfof Li2ZnTi3O8ceramics was almost independent with the sintering temperatures. In particular, Li2ZnTi3O8ceramics by reaction-sintering method sintered at 1125 °C for 5 h exhibited good combination microwave dielectric properties of εr=21.7, Q×f=70 500 GHz (at 7.5 GHz) and τf=-13 ppm/°C.

Properties of Si3N4 Based Nanocomposites Prepared by Pressureless Sintering Method

2012 ◽  
Vol 532-533 ◽  
pp. 53-56
Author(s):  
Ming Li Li ◽  
Qiong Yu ◽  
Ying Xu ◽  
Qing Guo Lu ◽  
Chun Jiang Zhou
Keyword(s):  
Dielectric Properties ◽  
Xrd Analysis ◽  
Pressureless Sintering ◽  
Low Density ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Main Crystalline Phase ◽  
Amorphous Si ◽  
Sintering Method

Si3N4 based nanocomposites were prepared with nano-sized amorphous SiO2 and Si3N4 powders by pressureless sintering method. The microstructures, phase composition, mechanical and dielectric properties of the nanocomposites were investigated. The scanning electrical microscope (SEM) photographs reveal that the grains are big and elongated. The X-ray diffraction (XRD) analysis shows that the main crystalline phase in the composites is Si2N2O formed during the sintering process. More β-Si3N4 phases were retained in the nanocomposites with the increase amount of the amorphous Si3N4 powders and no phase of SiO2 were observed. The densities and the strength of the nanocomposites decreased with the increase of amorphous SiO2 content. Despite low density, the flexural strengths of the composites reaches 220MPa and the ceramic has excellent dielectric properties with dielectric constant as low as 3.2-4.7 and dielectric loss in the range 2.6-3.9×10-3.

Study on Microstructure and Mechanical Properties of Ni/TiC Composites by Laser Induced Self-Propagating High-Temperature Synthesis

2011 ◽  
Vol 239-242 ◽  
pp. 1072-1075
Author(s):  
Yu Xin Li ◽  
Pei Kang Bai
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Sintered Density ◽  
Bending Strength ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis

Ni/TiC composites have been produced using laser induced self-propagating high-temperature synthesis. The chemical composition and microstructure were investigated by means of X-ray diffraction and scanning electron microscope. The sintered density and mechanical properties such as bending strength and micro-hardness were also measured. The results showed that the synthesized products were consisted of TiC and Ni phases, which indicated that the TiC was synthesized by the in-situ reaction. Moreover, the results revealed that the sintered density increased and the micro-hardness and bending strength of the synthesized products gradually decreased with the increasing of Ni contents.

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