Thermochemical preparation of W–25%Cu nanocomposite powder through a CVT mechanism

Hashempour, Mazdak; Razavizadeh, H.; Rezaie, Hamid Reza; Salehi, Mohammad Taghi

doi:10.1016/j.matchar.2009.05.001

Cited by 36 publications

(22 citation statements)

References 22 publications

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“…In general, CuWO 4 Á2H 2 O crystals are easily produced by the reaction between copper nitrate and sodium tungstate precursors in aqueous solutions, using specific pH and temperature conditions. Some published papers have reported on the structural features, morphological aspects and electronic properties of this tungstate [3][4][5][6][7][8][9][10][11][12]. Particularly, some of these studies [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

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Structural evolution, growth mechanism and photoluminescence properties of CuWO4 nanocrystals

Souza

Sczancoski

Nogueira

et al. 2017

Ultrasonics Sonochemistry

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Copper tungstate (CuWO) crystals were synthesized by the sonochemistry (SC) method, and then, heat treated in a conventional furnace at different temperatures for 1h. The structural evolution, growth mechanism and photoluminescence (PL) properties of these crystals were thoroughly investigated. X-ray diffraction patterns, micro-Raman spectra and Fourier transformed infrared spectra indicated that crystals heat treated and 100°C and 200°C have water molecules in their lattice (copper tungstate dihydrate (CuWO·2HO) with monoclinic structure), when the crystals are calcinated at 300°C have the presence of two phase (CuWO·2HO and CuWO), while the others heat treated at 400°C and 500°C have a single CuWO triclinic structure. Field emission scanning electron microscopy revealed a change in the morphological features of these crystals with the increase of the heat treatment temperature. Transmission electron microscopy (TEM), high resolution-TEM images and selected area electron diffraction were employed to examine the shape, size and structure of these crystals. Ultraviolet-Visible spectra evidenced a decrease of band gap values with the increase of the temperature, which were correlated with the reduction of intermediary energy levels within the band gap. The intense photoluminescence (PL) emission was detected for the sample heat treat at 300°C for 1h, which have a mixture of CuWO·2HO and CuWO phases. Therefore, there is a synergic effect between the intermediary energy levels arising from these two phases during the electronic transitions responsible for PL emissions.

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Section: Introductionmentioning

confidence: 99%

“…Particularly, some of these studies [3][4][5][6][7]. consider the CuWO 4 Á2H 2 O as a raw or precursor precipitate formed during the initial synthesis stages due to its favorable thermodynamic condition [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Structural evolution, growth mechanism and photoluminescence properties of CuWO4 nanocrystals

Souza

Sczancoski

Nogueira

et al. 2017

Ultrasonics Sonochemistry

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“…Recently, it was shown that the sinterability of the powders was enhanced significantly by using composite powders instead of the mixture ones [6]. Several methods like such as ball milling [7,8], thermochemical [9] sol gel [10] and chemical precipitation [11][12][13] has been applied for synthesizing fine dispersed composite powders such as W/Cu [14,15], W/Ag [16], Ag/ZnO [17] WC/Cu [18] and Cu/Al 2 O 3 [19]. The effect of sintering temperature on densification of the composite powders has been investigated by many researchers.…”

Section: Introductionmentioning

confidence: 99%

Cold compaction behavior and pressureless sinterability of ball milled WC and WC/Cu powders

2016

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In this research, cold compaction behavior and pressureless sinterability of WC, WC-10%wtCu and WC-30%wtCu powders were investigated. WC and WC/Cu powders were milled in a planetary ball mill for 20h. The milled powders were cold compacted at 100, 200, 300 and 400 MPa pressures. The compressibility behavior of the powders was evaluated using the Heckel, Panelli-Ambrosio and Ge models. The results showed that the Panelli-Ambrosio was the preferred equation for description the cold compaction behavior of the milled WC and WC-30%wtCu powders. Also, the most accurate model for describing the compressibility of WC-10%wtCu powders was the Heckel equation. The cold compacts were sintered at 1400 o C. It was found that by increasing the cold compaction pressure of powder compacts before sintering, the sinterability of WC-30%wtCu powder compacts was enhanced. However, the cold compaction magnitude was not affected significantly on the sinterability of WC and WC-10%wtCu powders. The microstructural investigations of the sintered samples by Scanning Electron Microscopy (SEM) confirmed the presence of porosities at the interface of copper-tungsten carbide phases.

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“…For instance, it is usually used as heavy-duty electrical contacts, material for electronic packaging, as well as a device for cooling and heat sinking. Nowadays, an increasing number of reliable components made with W-Cu composite are applied in fields of military or aerospace industries [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Research on vacuum brazing of W-Cu composite to stainless steel with Cu-Mn-Co brazing metal

Liang

Xia

et al. 2015

Science and Engineering of Composite Materials

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Research on vacuum brazing of W-Cu composite to stainless steel with Cu-Mn-Co brazing metalAbstract: This thesis is a discussion on obtaining a vacuum brazing joint of W-Cu alloy and 18-8 stainless steel with Cu-Mn-Co filler metal under the process parameter of a brazing temperature of 1060°C and holding time of 1 h. Four-point bending strength was tested at room temperature. Microstructure, microhardness, and element distribution near the interface of the brazed seam were observed via micro sclerometer, scanning electron microscope (SEM), and energy disperse spectroscopy (EDS) methods. Finally, analysis of the existence for phase composition near the interface was conducted using X-ray diffraction. Corresponding to a four-point bend strength of 780 MPa, there was a plain-interface, dense microstructure without obvious microdefects that formed. Microhardness values increased near the interface of the brazed joint and decreased gradually to the center of the brazed seam. Element distribution indicated that elements (Cu, Mn, Co) from the filler metal diffused into the interface or even substrates, and Fe and Cu element, together with a little of W element, from the substrates dissolved into the brazed seam region. Fracture morphology of the W-Cu/18-8 steel joint was identified as a mixed feature of fracture type. Moreover, the brazing seam contained mainly a Cu-rich phase, W 0.4 Cu 0.6 , α-Fe, and simple substance of W, together with a little of Co 0.7 Fe 0.3 .

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Thermochemical preparation of W–25%Cu nanocomposite powder through a CVT mechanism

Cited by 36 publications

References 22 publications

Structural evolution, growth mechanism and photoluminescence properties of CuWO4 nanocrystals

Structural evolution, growth mechanism and photoluminescence properties of CuWO4 nanocrystals

Cold compaction behavior and pressureless sinterability of ball milled WC and WC/Cu powders

Research on vacuum brazing of W-Cu composite to stainless steel with Cu-Mn-Co brazing metal

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