Defects in silicon carbide

Stevens, R. N.

doi:10.1007/bf00761949

Cited by 58 publications

(12 citation statements)

References 17 publications

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“…The stacking fault energy in 6H±SiC has been estimated to be 1.9 and 2.5 mJ/m 2 , by Stevens [50] and Maeda et al [51], respectively. This stacking fault energy is very low, compared with the stacking fault energies of f.c.c.…”

Section: Microstructural Defects In As-pressed Sic and Ruptured Fragmmentioning

confidence: 98%

Damage evolution in dynamic deformation of silicon carbide

et al. 2000

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AbstractÐDamage evolution was investigated in silicon carbide by subjecting it to dynamic deformation in (a) a compression Hopkinson±Kolsky bar (compressive stresses of 5 GPa), and (b) high-velocity impact under con®nement (compressive stresses of 19±32 GPa) by a cylindrical (rod) tungsten alloy projectile. Considerable evidence of plastic deformation, as dislocations and stacking faults, was found in the fractured specimens. A polytype transformation was observed through a signi®cant increase in the 6H±SiC phase at compressive stresses higher than 4.5 GPa (in the vicinity of the dynamic compressive failure strength). Profuse dislocation activity was evident in the frontal layer in the specimen recovered from the projectile impact. The formation of this frontal layer is proposed to be related to the high lateral con®ne-ment, imposed by the surrounding material. It is shown that plastic deformation is consistent with an analysis based on a ductility parameter D K C at y pc p ). The microstructural defects and their evolution were found to be dependent on the concentration of boron and aluminum, which were added as sintering aids. Several mechanisms are considered for the initiation of fracture: (a) dilatant cracks induced by mismatch in the eective elastic moduli between two adjacent grains, leading to internal tensile stresses and creating transgranular fracture. Finite element calculations show that high tensile stresses are generated due to elastic compatibility strains; (b) Zener±Stroh cracks nucleated by the piled up dislocations along grain boundaries, and resulting in intergranular fracture; (c) cracks due to existing¯aws connected with grain-boundary phases, voids, etc.; and (d) stress concentrations due to twinning and stacking faults. The high dislocation density observed in the impacted specimen is consistent with existing models of microplasticity. 7

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Section: Microstructural Defects In As-pressed Sic and Ruptured Fragmmentioning

confidence: 98%

Damage evolution in dynamic deformation of silicon carbide

et al. 2000

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“…However, the observed dislocations are on the top surface with an extension to a depth of ~5m only; therefore, it is hard to justify that the shear stress generated by the normal and tangent force on the friction interface contributed the development of these dislocation. In fact, these dislocations are more likely develop as those generated through an abrasion process in other ceramics 27,28 On the other hand, plastic deformation could become another mechanism of surface cracking damage, through piling up of dislocations due to constrained mobility of the front of a slip 27 and/or the interaction among the slips, where when a tensile is high enough, microcracking can be initiated. However, an intensive interaction among the slips was not observed in this study, as shown in Figure 6, so was constrained slips.…”

Section: ∑ (20)mentioning

confidence: 99%

Friction and surface fracture of a silicon carbide ceramic brake disc tested against a steel pad

Bian

2015

Journal of the European Ceramic Society

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“…The bright field TEM images showed irregular stacking faults along the {111} planes in the microcrystalline SiC layer. The formation energy for these stacking faults in β-SiC is very low (1.9 mJ/m 2 ) [16] thus they can easily be formed under thermal stresses during sintering. Steps were observed at the SiC-diamond interface, suggesting local etching and roughening of diamond {100} surface.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of SiC crystals growth on {100} and {111} diamond surfaces upon microwave heating

Unifantowicz

Vaucher

Lewandowska

et al. 2010

Materials Characterization

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The subject of this work is focused on characterization of the microstructures and orientations of SiC crystals synthesized in diamond-SiC-Si composites using reactive microwave sintering. The SiC crystals grown on the surfaces of diamonds have either shapes of cubes or hexagonal prisms, dependent on crystallographic orientation of diamond. The selection of a specified plane in diamond lattice for the TEM investigations IntroductionDiamond-SiC composites are considered one of the most promising materials for thermal management applications. In contrast with metal-based diamond composites, diamond-SiC potentially combine high thermal conductivity and relatively low coefficient of thermal expansion of two phases each having a low density. Chemical bonding between the diamond particles and the SiC should be provided by a reaction between carbon and silicon to form 'bridges' structurally integrated with diamond. However, the thermal resistance of SiC-diamond interfaces should be minimised to ensure efficient heat transport in the interconnected diamonds [1,2]. This can be achieved by providing defect-free, coherent interfaces between the diamond and the SiC lattices. It should be noted that the SiC crystals can grow on diamond either in an ordered fashion, resulting in highly strained epitaxial layers, low energy semi-coherent configurations [3,4] or through high-misfit interfaces with lattice defects minimizing the strain energy [5]. Numerous investigations have been carried out on the structure of SiCdiamond interfaces [5][6][7][8][9]. However, to the best knowledge of the authors, the growth mechanism of SiC crystals grown on differently oriented diamond surfaces has not been studied and experimentally verified.The diamond-SiC composites can be fabricated via hightemperature high-pressure sintering of diamond and Si [6-9], infiltration of diamond compacts with precursor gas [10] and more recently by microwave reactive sintering of diamondsilicon powders mixtures [11,12]. In contrast to the conventional processes, microwave sintering has the advantage of internal and phase-selective heat generation which offers high sintering rates [13]. Since silicon has a much higher dielectric loss than diamond, it more readily absorbs microwave energy and is preferentially heated to temperatures above its melting point [14]. The higher heating rate facilitated

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Defects in silicon carbide

Cited by 58 publications

References 17 publications

Damage evolution in dynamic deformation of silicon carbide

Damage evolution in dynamic deformation of silicon carbide

Friction and surface fracture of a silicon carbide ceramic brake disc tested against a steel pad

Mechanism of SiC crystals growth on {100} and {111} diamond surfaces upon microwave heating

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