Experimental investigations on the synthesis of W–Cu nanocomposite through spark plasma sintering (original) (raw)
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Effect of Nano Copper on the Densification of Spark Plasma Sintered W–Cu Composites
Nanomaterials, 2021
In the present work, nano Cu (0, 5, 10, 15, 20, 25 wt.%) was added to W, and W–Cu composites were fabricated using the spark plasma sintering (S.P.S.) technique. The densification, microstructural evolution, tensile strength, micro-hardness, and electrical conductivity of the W–Cu composite samples were evaluated. It was observed that increasing the copper content resulted in increasing the relative sintered density, with the highest being 82.26% in the W75% + Cu25% composite. The XRD phase analysis indicated that there was no evidence of intermetallic phases. The highest ultimate (tensile) strength, micro-hardness, and electrical conductivity obtained was 415 MPa, 341.44 HV0.1, and 28.2% IACS, respectively, for a sample containing 25 wt.% nano-copper. Fractography of the tensile tested samples revealed a mixed-mode of fracture. As anticipated, increasing the nano-copper content in the samples resulted in increased electrical conductivity.
An experimental investigation on the W–Cu composites
Materials & Design, 2009
Fabrication of tungsten-copper net-shapes has become an important issue in recent years due to their unique properties which make them suitable for a wide variety of applications. In this investigation, W-Cu composite powders containing 20 wt.% and 30 wt.% Cu were processed by powder metallurgy technique using two types of prepared powders, namely, Cu-coated tungsten and mixtures of elemental powders. The coating method of tungsten powders was carried out using electroless coating technique. The investigated powders were cold compacted and sintered in vacuum at two sintering temperatures, 1250°C and 1400°C.
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Experimental investigations are performed in order to predict the mechanism of deformation and densification behaviour during cold upset forming operation on sintered Cu- 15%W Nano composite. High-energy mechanical milling was used to produce Cu and W Nano powder composites. Cylindrical preforms with initial theoretical density of 85% possessing three different aspect ratios of 0.40, 0.60 and 0.80 were prepared using a die and punch assembly with a hydraulic press. The preforms are sintered in an electric muffle furnace at 650°C, and subsequently the furnace was cooled. Cold deformation experiments are conducted in incremental deformation steps. The relationships between various parameters are evaluated
Acta Physica Polonica A, 2014
This study reports on the development of some WCuNi materials for use as electrical contacts for low voltage vacuum switching contactors for nominal currents up to 630 A. The contact materials with 85 wt% W, 1214 wt% Cu and 13 wt% Ni were obtained by spark plasma sintering process in vacuum. From very nely dispersed WCuNi powder mixtures there were produced sintered electrical contact pieces that were investigated in terms of physical, microstructural, mechanical, and functional properties. The material sintered at 1200 • C exhibited a near fully dense structure with very low porosity and enhanced mechanical properties: hardness of maximum 480 HV1 and elastic modulus of maximum 220 GPa and low chopping current of maximum 1.77 A.
Materials & Design, 2011
Elemental powders of copper (Cu), tungsten (W) and graphite (C) were mechanically alloyed in a planetary ball mill with different milling durations (0-60 h), compacted and sintered in order to precipitate hard tungsten carbide particles into a copper matrix. Both powder and sintered composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and assessed for hardness and electrical conductivity to investigate the effects of milling time on formation of nanostructured Cu-WC composite and its properties. No carbide peak was detected in the powder mixtures after milling. Carbide WC and W 2 C phases were precipitated only in the sintered composite. The formation of WC began with longer milling times, after W 2 C formation. Prolonged milling time decreased the crystallite size as well as the internal strain of Cu. Hardness of the composite was enhanced but electrical conductivity reduced with increasing milling time.
PREDICTION OF BEHAVIOUR IN FORMING OF SINTERED COPPER-10% TUNGSTEN NANO POWDER COMPOSITE
Experimental investigations are performed in order to predict the mechanism of deformation and densification behaviour during cold upset forming operation on sintered Cu- 10%W Nano composite. High-energy mechanical milling was used to produce Cu and W Nano powder composites. Cylindrical preforms with initial theoretical density of 85% possessing three different aspect ratios of 0.40, 0.60 and 0.80 were prepared using a die and punch assembly with a hydraulic press. The preforms are sintered in an electric muffle furnace at 650°C, and subsequently the furnace was cooled. Cold deformation experiments are conducted in incremental deformation steps. The relationships between various parameters are evaluated
Evaluation of microstructure and contiguity of W/Cu composites prepared by coated tungsten powders
International Journal of Refractory Metals and Hard Materials, 2009
In this paper, infiltration behavior of W/Cu composite compacts made from coated tungsten powder has been investigated. For this purpose, tungsten particles were coated with Ni, NiP and Ni-CuP using electroless plating technique. Then the coated tungsten powders were compacted under selective pressures for control infiltrated copper in range 10-20 wt%. Infiltration process was carried out at 1300°C under a reducing atmosphere. The effect of pre-coat of tungsten particles on microstructure, contiguity and density of infiltrated W/Cu compacts was evaluated by OM/SEM, EDS and Archimedes methods. It was found that electroless plating of tungsten particles leads to more homogeneity microstructure so relative density of 99.3% was achieved for infiltrated compacts. The contiguity of W-W particles in the microstructure of composite made from Ni-CuP coated tungsten powder was lower than to other ones.
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This study investigates the sintering behaviour and properties of WC-based composites in which WC was mixed with W5vol%Ni in concentrations of 10vol% and 20vol%. Colloidal processing in water and spark plasma sintering were employed to disperse the WC particles and facilitate sintering. The addition of W5vol%Ni improved the sintering process, as evident from a lower onset temperature of shrinkage determined through dilatometric studies. All samples exhibited the formation of tungsten monocarbide (W2C), with a more pronounced presence in the WC/20(W5vol%Ni) composite. Sintering reached its maximum rate at 1550 °C and was completed at 1600 °C, resulting in a final density exceeding 99.8%. X-ray diffraction analysis confirmed the detection of WC and W2C phases after sintering. The observed WC content was higher than expected, which may be attributed to carbon diffusion during the process. Macro-scale mechanical characterisations revealed that the WC/10(W5vol%Ni) composite exhibited a h...
Properties of W–Cu composite powder produced by a thermo-mechanical method
International Journal of Refractory Metals and Hard Materials, 2003
In order to improve the process of co-reduction of oxide powder, a new thermo-mechanical method was designed to produce high-dispersed W-Cu composite powder by high temperature oxidation, short time high-energy milling and reduction. The properties of W-Cu composite powder are analyzed in terms of oxygen contents, BET specific surface (BET-S), particle size distributions, morphology of final powder and their sintering behaviors. The results show that the oxygen content of W-Cu composite powder decreases with the increase of milling time, while the BET-S of final powder increases with the milling time. The distributions of final powder are more uniform after reduction at 630°C than at 700°C. After milling of the oxide powder for about 3-10 h, W-Cu composite powder with very low oxygen content can be achieved at the reduction temperature of 630°C owning to the increasing of BET-S of W-Cu oxide powder. The particle size of W-Cu powder after reduction is lower than 0.5 lm and smaller than that reduced at 700°C. After sintering at 1200°C for 60 min, the relative density and thermal conductivity of final products (W-20Cu) can attain 99.5% and 210 W m À1 K À1 respectively.
International Journal of Refractory Metals and Hard Materials, 2012
The properties of W-15 wt.%Cu composites were investigated by preparing two distinct composites of micrometer and nanoscale structures. Micrometer composite was produced by mixing elemental W and Cu powders and nanometer one was synthesized through a mechanochemical reaction between WO 3 and CuO powders. Subsequent compaction and sintering process was performed to ensure maximum possible densification at 1000-1200°C temperatures. Finally, the behavior of produced samples including relative density, hardness, compressive strength, electrical conductivity, coefficient of thermal expansion (CTE) and room temperature corrosion resistance were examined. Among the composites, nano-structured sample sintered at 1200°C exhibited better homogeneity, the highest relative density (94%) and mechanical properties. Furthermore, this composite showed superior electrical conductivity (31.58 IACS) and CTE (9.95384× 10-6) in comparison with micrometer type. This appropriate properties may be mainly attributed to liquid phase sintering with particle rearrangement which induced by higher capillary forces of finer structures.