Influence of the interface strength on the mechanical properties of discontinuous tungsten fiber-reinforced tungsten composites produced by field assisted sintering technology

Mao, Y.; Coenen, J. W.; Riesch, J.; Sistla, S.; Almanstötter, J.; Jasper, B.; Terra, A.; Höschen, T.; Gietl, H.; Linsmeier, Ch.; Broeckmann, Christoph

doi:10.1016/j.compositesa.2018.01.022

Cited by 78 publications

(74 citation statements)

References 52 publications

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“…Between fiber and matrix, the yttrium oxide interface is still visible after sintering. However the layer also gets partially damaged due to the high temperature and pressure during the sintering process similar to the results in [5,33]. During the production process, the external pressure will deform the yttrium oxide interface as it can be seen in Fig.…”

Section: Microstructuresupporting

confidence: 56%

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Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

et al. 2019

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In future fusion reactors, tungsten is considered as the main candidate material for plasma-facing components. However, the intrinsic brittleness of tungsten is of great concern during operation. To overcome this drawback, tungsten fiber-reinforced tungsten composites (Wf/W) are being 2 developed relying on extrinsic toughening principles. Tungsten (W) fibers with extremely high tensile strength and ductility are used to reinforce a tungsten matrix. In this work, field assisted sintering technology (FAST) is used to produce Wf/W material. Mechanical characterizations including Charpy impact and 3-point bending tests are performed. Based on the 3-point bending test results, the Wf/W materials can facilitate a promising pseudoductile behavior even at room temperature, similar to fiber reinforced ceramic composites. Fracture energy density and fracture toughness together with the crack-resistance curves (R-curves) are measured. Compared to conventional pure tungsten, Wf/W shows significant improvement in fracture toughness.

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Section: Microstructuresupporting

confidence: 56%

“…However, as it is technically difficult to introduce aligned long fibers into the bulk material in the FAST process. Therefore, short fibers with random distribution are used to realize the reinforcement [5].…”

Section: Introductionmentioning

confidence: 99%

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

et al. 2019

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“…Eventually, the maximum compressive stress of sample A reached 117 MPa with ~52% strain (perpendicular to the channels). Such a feature is known as pseudo‐ductility and also occurs in mullite fibrous ceramics . When the compressive load was parallel to the channels (Figure B), the maximum stress of sample A was improved to 114 MPa with a strain of ~17%.…”

Section: Resultsmentioning

confidence: 91%

“…The fiber coating contained both shear and tension stresses when the orientation angles of fibers 1 and 2 to the load direction (α) were within 0‐90°. When α was small, the debonding of the coating was mainly caused by shear stress and occurred according to the following criterion: before the carbon fiber broke, the maximum shear stress ( τ ) of the coating should be higher than the shear strength of the coating ( τ c ). Based on the shear lag model, the shear stress distribution on the fiber coating can be described as follows:

τ = τ_{av} η \frac{l}{2} (sinh η z - coth η \frac{l}{2} cosh η z)

τ_{normalav} = \frac{r_{normalf} σ}{l}

η = \sqrt{\frac{2 G_{i}}{E_{f} (r_{normalm} - r_{normalf}) r_{f}}}

r_{normalm} = r_{normalf} \sqrt{\frac{false(1 + v_{f} false)}{v_{normalf}}}

…”

Section: Resultsmentioning

confidence: 99%

Fabrication of high‐strength porous SiC‐based composites with unidirectional channels

et al. 2019

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Carbon fiber reinforced SiC-based composites with unidirectional channels were obtained by freeze-casting and chemical vapor infiltration techniques, and their microstructure and fracture behavior were investigated. The results indicated that the sizes of the unidirectional channels could be controlled in the 15-70 μm range. The significant pseudo plastic and ductility features of the porous SiC-based composite were demonstrated during the fracture process. The strains of the composites reached 4 ± 1% and 50 ± 6% during bending and compressive experiments, respectively. The bending and compressive strengths, 123 ± 20 and 99 ± 15 MPa, respectively, were far superior to those of homogeneous ceramics presenting the same porosity. Combining the aforesaid method with 3D printing techniques, a SiC-based composite part with controlled macro-micro channels was fabricated, which indicated that this method could be useful for fabricating ceramic parts with complex structure and superior mechanical performance. K E Y W O R D Scarbon fibers, freeze-casting, mechanical properties, SiC-based composite

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“…Thus it is one of the most promising candidates as interface for W f /W. Furthermore Mao could show that reinforcing W f /W samples produced by field assisted sintering technology (FAST) with discontinuous fibers coated with yttrium oxide (Y 2 O 3 ) results in significant toughening [22]. Figure 2 shows a typical force-displacement curve of a push-out test as discussed by Chandra et al [23].…”

Section: Interface Properties Of W F /Wmentioning

confidence: 96%

Insight into single-fiber push-out test of tungsten fiber-reinforced tungsten

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Jasper

Coenen

et al. 2018

Composite Interfaces

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To overcome the intrinsic brittleness of tungsten (W), a tungsten fiber-reinforced tungsten-composite material (W f /W) is a possible solution. The introduction of energy dissipation mechanisms like fiber bridging or fiber pull-out by means of an engineered interface between fiber and matrix mitigate the brittleness of tungsten and lead to a pseudo-ductile material behaviour. The push-out test of single-fiber samples is an experimental method to investigate the properties of the interface between fiber and matrix of composite materials. It is widely used for the investigation of ceramic composites. This method was also used to investigate the debonding and frictional properties of the Er2O3 interface region between fiber and matrix of W f /W single-fiber samples made by CVD-and HIP-processes. In this article finite element calculations are used to get a better understanding of the processes acting in the interface during a push-out test of W f /W. A detailed overview of the debonding progress and of the corresponding stress states of the interface during the different stages of the test is presented. In addition the sensitivity of the push-out behaviour regarding the different interface properties and the plastic flow curve of the tungsten fiber are investigated.

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Influence of the interface strength on the mechanical properties of discontinuous tungsten fiber-reinforced tungsten composites produced by field assisted sintering technology

Cited by 78 publications

References 52 publications

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

Fabrication of high‐strength porous SiC‐based composites with unidirectional channels

Insight into single-fiber push-out test of tungsten fiber-reinforced tungsten

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