scholarly journals Electrical and mechanical properties of Cu-CNT nanocomposites sintered by microwave technique

2018 ◽  
Vol 23 (4) ◽  
pp. 303-317 ◽  
Author(s):  
Marjan Darabi ◽  
Masoud Rajabi
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Microwave Sintering ◽  
Multiwall Carbon Nanotubes ◽  
Physical And Mechanical Properties ◽  
Copper Matrix ◽  
Conventional Sintering ◽  
Novel Method ◽  
Sintering Method ◽  
Multiwall Carbon

In this research, multiwall carbon nanotubes were dispersed in a copper matrix using a planetary ball mill. The mixed powders were compacted using a uniaxial hydraulic presser. A novel method of microwave sintering was applied to consolidate Cu-CNT nanocomposites Conventional sintering method was also used to sinter samples to investigate the effects of applied methods on the properties of the sample. Sintering time was reduced to 20 min using microwave sintering method. The morphology and phase analysis of nanocomposites were studied by FESEM and XRD. The physical and mechanical properties of Cu-CNT nanocomposites were characterized using electrical conductivity, bending strength, and micro-hardness. The results show that the mechanical properties of Cu-CNT nanocomposites are improved significantly by microwave route. The optimum hardness and bending strength were obtained for 4 vol. % CNT as an optimum amount of reinforcement.

MICROWAVE SINTERING OF NANOCRYSTALLINE 8YSZ: EFFECT OF HEATING SCHEDULE ON MICROSTRUCTURE, IONIC CONDUCTIVITY, AND MECHANICAL PROPERTIES

2009 ◽  
Vol 08 (03) ◽  
pp. 293-298
Author(s):  
MAHDIAR VALEFI ◽  
CAVUS FALAMAKI ◽  
AHAD FATTAHI ◽  
TOURAJ EBADZADEH
Keyword(s):  
Mechanical Properties ◽  
Ionic Conductivity ◽  
Microwave Sintering ◽  
The Novel ◽  
Zirconia Powder ◽  
Step Method ◽  
One Step ◽  
Novel Method ◽  
Heating Schedule ◽  
Sintering Method

Nanocrystalline 8 mol.% yttria-stabilized zirconia powder prepared from a combustion synthesis route has been sintered using microwave (MW) energy by two routes: Conventional one-step and a novel two-step method. The final products from the two routes have been compared regarding their microstructure, ion-conductivity, and mechanical properties. It is shown that it is possible to produce highly dense compacts with significant smaller grains using the novel two-step MW sintering method with significant smaller energy consumption with respect to conventional one-step MW assisted sintering. The novel method is able to produce sintered samples with near similar ionic conductivity at temperatures higher than 700°C and slightly lower mechanical properties at room temperature.

Microstructure and Properties of Microwave Sintered 40 wt. % WC Steel-Bonded Carbides

2011 ◽  
Vol 335-336 ◽  
pp. 836-840 ◽  
Author(s):  
Jun Ming Luo ◽  
Zheng Wei ◽  
Ji Lin Xu ◽  
Li Ping Deng
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Bending Strength ◽  
Microwave Sintering ◽  
Strengthening Mechanism ◽  
Sintering Behavior ◽  
Transgranular Fracture ◽  
Strengthening Effect ◽  
Steel Matrix ◽  
Conventional Sintering

40 wt. %WC steel-bonded carbides were prepared by microwave sintering. The sintering behavior and mechanical properties of 40 wt. %WC-Fe were investigated in comparison with 0 wt. %WC-Fe. The green compact of 40 wt. %WC-Fe sintered at 1280 °C, the phase transition between WC and Fe is observed, generating new Fe2W2C phase. The phase transition promotes the densification of the sample, which plays a strengthening effect on the material. Microwave sintering possesses even quicker densification than conventional sintering, as well as substantially higher mechanical properties. The microhardness and bending strength of steel-bonded carbides prepared by microwave sintering are 10% ~ 20% higher than the conventional sintering. The microhardness of 40 wt. %WC-Fe is up to 544 HV, eight times higher than that of 0 wt. %WC-Fe and the bending strength of 40 wt. %WC-Fe is three times higher than that of 0 wt. %WC-Fe. Strengthening mechanism of 40 wt. %WC-Fe samples is that the Fe2W2C rigid phase dispersed over the steel matrix is not deformation, and plays the effect of hindering dislocation motion. The fracture mode is mixed intergranular fracture and transgranular fracture, belonging to brittle fracture.

scholarly journals Effects of directly added or reaction formed TiB2 on the microstructure and mechanical properties of pressureless-sintered B4C–TiB2 composites

2020 ◽  
Author(s):  
Zongjia Li ◽  
Yangwei Wang ◽  
Huanwu Cheng ◽  
Yu Zhu ◽  
Rui An ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Boron Carbide ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Submicron Particles ◽  
Matrix Composites ◽  
Effective Role ◽  
Carbide Matrix ◽  
Sintering Method

Abstract The boron carbide matrix composites containing boron carbide (B 4 C), titanium diboride (TiB 2 ; 20 wt% and 30 wt%) and titanium carbide (TiC) were fabricated at 2130 °C using the pressureless sintering method. Different amounts of TiB 2 and TiC particles were added to B 4 C, and the TiB 2 content was chosen as the main variable to study the effect on the composites. The density, hardness, bending strength and fracture toughness measurements were performed to obtain the physical and mechanical properties of the samples. The obtained results indicate that by adding 30 wt% TiB 2 submicron particles at 2130 °C, the bending strength and fracture toughness of 277.6 MPa and 5.38 MPa·m 1/2 are obtained for the composite. The particle pullout and crack microbridging play an effective role in toughening the composite ceramics. The main toughening mechanisms of the B 4 C-TiB 2 composites are noted to be microcrack and crack deflection toughening owing to the residual stresses resulting from the mismatch of the thermal expansion coefficient between TiB 2 and B 4 C.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

scholarly journals Eco-Friendly, High-Density Fiberboards Bonded with Urea-Formaldehyde and Ammonium Lignosulfonate

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 220
Author(s):  
Petar Antov ◽  
Viktor Savov ◽  
Ľuboš Krišťák ◽  
Roman Réh ◽  
George I. Mantanis
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Urea Formaldehyde ◽  
Physical And Mechanical Properties ◽  
High Density ◽  
Thickness Swelling ◽  
Formaldehyde Content ◽  
Uf Resin ◽  
Natural Wood ◽  
European Standards

The potential of producing eco-friendly, formaldehyde-free, high-density fiberboard (HDF) panels from hardwood fibers bonded with urea-formaldehyde (UF) resin and a novel ammonium lignosulfonate (ALS) is investigated in this paper. HDF panels were fabricated in the laboratory by applying a very low UF gluing factor (3%) and ALS content varying from 6% to 10% (based on the dry fibers). The physical and mechanical properties of the fiberboards, such as water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), bending strength (MOR), internal bond strength (IB), as well as formaldehyde content, were determined in accordance with the corresponding European standards. Overall, the HDF panels exhibited very satisfactory physical and mechanical properties, fully complying with the standard requirements of HDF for use in load-bearing applications in humid conditions. Markedly, the formaldehyde content of the laboratory fabricated panels was extremely low, ranging between 0.7–1.0 mg/100 g, which is, in fact, equivalent to the formaldehyde release of natural wood.

scholarly journals Effect of Sintering Temperature on Microstructure and Mechanical Properties of Hot-Pressed Fe/FeAl2O4 Composite

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 422
Author(s):  
Kuai Zhang ◽  
Yungang Li ◽  
Hongyan Yan ◽  
Chuang Wang ◽  
Hui Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Hot Press ◽  
Microstructure And Mechanical Properties ◽  
Powder Particles ◽  
Hot Press Sintering ◽  
Sintering Method

An Fe/FeAl2O4 composite was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method. The mass ratio was 6:1:2, sintering pressure was 30 MPa, and holding time was 120 min. The raw materials for the powder particles were respectively 1 µm (Fe), 0.5 µm (Fe2O3), and 1 µm (Al2O3) in diameter. The effect of sintering temperature on the microstructure and mechanical properties of Fe/FeAl2O4 composite was studied. The results showed that Fe/FeAl2O4 composite was formed by in situ reaction at 1300 °C–1500 °C. With the increased sintering temperature, the microstructure and mechanical properties of the Fe/FeAl2O4 composite showed a change law that initially became better and then became worse. The best microstructure and optimal mechanical properties were obtained at 1400 °C. At this temperature, the grain size of Fe and FeAl2O4 phases in Fe/FeAl2O4 composite was uniform, the relative density was 96.7%, and the Vickers hardness and bending strength were 1.88 GPa and 280.0 MPa, respectively. The wettability between Fe and FeAl2O4 was enhanced with increased sintering temperature. And then the densification process was accelerated. Finally, the microstructure and mechanical properties of the Fe/FeAl2O4 composite were improved.

scholarly journals A novel method of sintering hybrid steels in an improved semiclosed container system

2013 ◽  
Vol 45 (3) ◽  
pp. 379-383 ◽  
Author(s):  
A. Cias
Keyword(s):  
Mechanical Properties ◽  
Structural Steels ◽  
Laboratory Scale ◽  
The Other ◽  
Reduction Reactions ◽  
High Affinity ◽  
Conventional Sintering ◽  
Superior Mechanical Properties ◽  
Novel Method

Conventional sintering techniques for structural steels have been developed principally for Cu and Ni containing alloys. Applying these to Cr and Mn steels (successful products of traditional metallurgy) encounter the problem of the high affinity for oxygen of these elements. A solution is employing a microatmosphere in a semiclosed container which favours reduction reactions. This has already proved successful on a laboratory scale, especially with nitrogen as the furnace gas. Further modifications to the system, now described, include the use of two sintering boxes, one inside the other. Superior mechanical properties, even using air as the furnace gas, are attainable.

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