“…Figure 7 shows the abundance of porosities in each composite sample based on the experimental measurement under investigation. As reported by Yusefi et al, 29 minimum porosities were observed in the layer with W70/Cu30 composition, through composition change increased the porosity abundance. According to Figure 7, the minimum porosity belonged to three-layered and four-layered FGCs, which were about 4.47% and 4.65%, respectively.…”
Section: Resultssupporting
confidence: 75%
“…The Archimedes’s method was applied to measure the porosity percent and density of samples, as ASTM B962-14 standard. 29,30 Then, the porosity of the sample was calculated based on theoretical density calculations. Figure 7 shows the abundance of porosities in each composite sample based on the experimental measurement under investigation.…”
In this study, a functionally graded composite (FGC) technique is proposed to produce an electrical contact material made of W/Cu alloy. The prepared composite was sintered and subjected to high-voltage vacuum arc erosion. The composite properties and microstructure are carefully studied based on SEM images before and after exposure to vacuum arc discharge. According to the necking phenomenon observed in the electron micrographs and the quantitative analysis of the particle size, it is evident that the intermediate layer of W/Cu FGC has been in the final stage of the sintering process. The present porosity of FGC samples was less than mono-layered composite (MLC) samples, and the minimum porosity was observed in the three-layered FGC that composed of W70/Cu30 in the first layer. The average hardness of FGC samples was 4% higher than that of MLC samples with an identical composition. The results of the erosion behavior assessment were used to determine the possible arc erosion mechanism. The weight loss was diminished upon erosion when the W/Cu alloys had more than one layer, especially in four-layered FGC. The result also revealed that FGC samples, especially the four-layered composite, had improved heat transfer and prevented heat concentration on the contact surfaces due to higher content of Cu particles in the successive layers and consequently reduced the surface damage.
“…Figure 7 shows the abundance of porosities in each composite sample based on the experimental measurement under investigation. As reported by Yusefi et al, 29 minimum porosities were observed in the layer with W70/Cu30 composition, through composition change increased the porosity abundance. According to Figure 7, the minimum porosity belonged to three-layered and four-layered FGCs, which were about 4.47% and 4.65%, respectively.…”
Section: Resultssupporting
confidence: 75%
“…The Archimedes’s method was applied to measure the porosity percent and density of samples, as ASTM B962-14 standard. 29,30 Then, the porosity of the sample was calculated based on theoretical density calculations. Figure 7 shows the abundance of porosities in each composite sample based on the experimental measurement under investigation.…”
In this study, a functionally graded composite (FGC) technique is proposed to produce an electrical contact material made of W/Cu alloy. The prepared composite was sintered and subjected to high-voltage vacuum arc erosion. The composite properties and microstructure are carefully studied based on SEM images before and after exposure to vacuum arc discharge. According to the necking phenomenon observed in the electron micrographs and the quantitative analysis of the particle size, it is evident that the intermediate layer of W/Cu FGC has been in the final stage of the sintering process. The present porosity of FGC samples was less than mono-layered composite (MLC) samples, and the minimum porosity was observed in the three-layered FGC that composed of W70/Cu30 in the first layer. The average hardness of FGC samples was 4% higher than that of MLC samples with an identical composition. The results of the erosion behavior assessment were used to determine the possible arc erosion mechanism. The weight loss was diminished upon erosion when the W/Cu alloys had more than one layer, especially in four-layered FGC. The result also revealed that FGC samples, especially the four-layered composite, had improved heat transfer and prevented heat concentration on the contact surfaces due to higher content of Cu particles in the successive layers and consequently reduced the surface damage.
“…The effect of various processing parameters such as sintering time, temperature and compaction pressure on the mechanical and wear characteristics were systematically studied. In [19], W–Cu FGCMs were fabricated for potential plasma-facing component applications in future fusion reactors (Figure 13, lower image). The binder alloy was created by mechanically alloying Ni, Cu and Mn metal powders.…”
Section: Manufacturing Methods Of Fgcmsmentioning
confidence: 99%
“…The distribution of both Cu and W particles in the fabricated composites was homogeneous; however, the samples possessed significant residual porosity in the range of 4–8%. Figure 13. Representative microstructures of FGCMs fabricated via pressureless sintering process: (a) optical micrograph of an FGCM starting from pure Ni layer to layers of Ni/WC-Co graded composites (layer C: 25 wt-% WC–Co/75 wt-% Ni, layer B: 50 wt-% WC–Co/50 wt-% Ni, layer A: 75 wt-% WC–Co/25 wt-% Ni). The insets (II–V) show enlarged views of the different interlayer regions [133], and (b) backscattered SEM image of the gradient microstructure in eleven-layered W–Cu FGCM [19] (cited images have been reproduced with due permission from the publisher).…”
Monolithic components are often insufficient when a combination of conflicting properties, or a variation in properties at different regions within a material is required. Functionally graded composite materials (FGCM) are a relatively new class of materials with a systematic variation of the composition, microstructure, and properties along one direction. The graded structure offers tailorable property combinations not achievable with monolithic composites and significant recent research has been carried out on their development. An effort has been made in this article to review the latest developments on bulk FGCMs since 2015. The different processing techniques used for their fabrication have been discussed, highlighting their advantages, limitations, and recent advancements pertaining to FGCM fabrication. Various physical, mechanical, and thermal properties of FGCMs have been treated separately, and wherever possible, summary plots combining data from various research articles have been developed. Finally, potential areas for directing future FGCM research have been identified.
“…A novel approach for fabrication W/Cu FGM with gradients in hardness and electric conductivity via the microwave processing was proposed by Zhou et al [15]. The W-Cu FGM with 11 layers by powder stacking was fabricated by Yusefi et al [16], which has high relative density and excellent sintering behavior. However, among above FGMs fabricated by the powder metallurgy methods, their composition distributions are not continuous.…”
To solve the debonding and fracture problems caused by the different thermal expansion coefficients of the transducer element and the measured object, a new method combined with the powder lamination, pressureless infiltration and hot pressing sintering is proposed to prepare Fe/PZT functionally graded material as the matching layer of transducers. The microstructure and element distribution of the functionally graded layer are analyzed by the SEM and EDS. The results show that the volume fraction and elements of the functionally graded layer after the pressureless infiltration at 1100 °C and the hot pressing at 800 °C are linearly and continuously distributed along the thickness direction. The thermal cycle contrast test shows the well matching performance of the functionally graded disk as the transducer matching layer from room temperature to 180 °C. Finally, Lamb wave propagation experiment at the 180 °C shows that the functionally graded matching layer can be used effectively.
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