In situ X-ray microtomography characterization of damage in SiCf/SiC minicomposites

Chateau, Camille; Gélebart, Lionel; Bornert, Michel; Crépin, Jérôme; Boller, Élodie; Sauder, Cédric; Ludwig, Wolfgang

doi:10.1016/j.compscitech.2011.02.008

Cited by 104 publications

(55 citation statements)

References 40 publications

(50 reference statements)

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“…The degradation mechanisms are in good agreement with results from a recent study conducted at CEA Saclay, emphasizing the dependence of the crack propagation with loading for CVI-SiC f /SiC minicomposites [8]. …”

Section: Discussionsupporting

confidence: 80%

Influence of an O2 Type Oxidizing Environment on SiCf/SiC Composites: Properties/Microstructure Relationship

et al. 2013

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Abstract. Ceramic matrix composites have been identified as a potential material of core structure for the IV th generation of fission nuclear reactors. Regarding its excellent mechanical behavior in very harsh conditions (high temperature and high irradiation flux), the CVI-SiC f /SiC composites with pyrocarbon interlayer are of prime interest for the fuel cladding in the Gas-cooled Fast Reactor (GFR). Although the working atmosphere is helium in these advanced reactors, presence of oxidizing impurities could have a significant role on the mechanical behavior of materials for a long time exposure. Within this framework, this study is intended to investigate the influence of oxidation on the SiC f /SiC composites mechanical properties. Different pre-damage states were intentionally operated by mechanical tensile tests on plate specimens before performing an oxidation treatment of 1000 hours at 1000°C under helium with 10 ppm of O 2 . The degradation of the composite was determined from the mechanical behavior of post-exposure specimens. Results were correlated both with microstructural observations of the damaged tows and with characterizations of the generated oxides at the surface of the composites. The most severe decline of mechanical properties occurs for the higher predamaged loadings. A degradation mechanism, depending on the damage state, is proposed to explain the mechanical behavior change in accordance to the different examinations.

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Section: Discussionsupporting

confidence: 80%

Influence of an O2 Type Oxidizing Environment on SiCf/SiC Composites: Properties/Microstructure Relationship

et al. 2013

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“…They reported that the damage mechanisms in PA/GF are characterized by matrix plasticization and microcracks, fiber pull out and fracture. X-ray micro-computed tomography (lCT) technique has been used to investigate damage mechanisms in various composite materials [14][15][16][17][18]. Thanks to its inherent 3D analysis capabilities, the damage mechanisms can be identified and quantified in the bulk material, though usually careful data treatments are needed such as to resolve the lower resolution of lCT voxel as compared to the damage size and the presence of artifacts [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

In situ damage mechanisms investigation of PA66/GF30 composite: Effect of relative humidity

Arif

Meraghni

Chemisky

et al. 2014

Composites Part B: Engineering

130

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. b s t r a c tDamage mechanisms of injection molded polyamide-66/short glass fiber 30 wt% composite (PA66/GF30) were analyzed using in situ SEM mechanical tests on specimens conditioned under three relative humidity contents (RH = 0%, 50% and 100%). The validity of these in situ analyses was confirmed by Xray micro-computed tomography (lCT) observations on tensile loaded specimens. Experimental results demonstrated that relative humidity (RH) conditions influence strongly the damage level and damage mechanisms. Indeed, for specimen with RH = 0%, damage initiation occurs at significantly higher load level than those in RH = 50% and RH = 100% specimens. The higher relative humidity condition also results in higher damage level. Damage chronologies have been proposed as damage initiation in the form of fiber-matrix debonding occurs at fiber ends and more generally at locations where fibers are close to each other due to the generation of local stress concentration (for all studied RH contents), and first fiber breakages occur (RH = 0%). These debonded zones further propagate through fiber-matrix interface (for all studied RH contents), and new fiber breakages develop (RH = 0%). At high relative flexural stress, matrix microcracks appear and grow regardless the RH contents. For RH = 100%, these microcracks are also accompanied by many matrix deformation bands. Subsequently, they lead to the damage accumulation and then to the final failure.

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“…Stitched images built from several high resolution images (1 pixel % 0.07 Â 0.07 lm 2 ) are used to get accurate statistical data about fibers and porosity distributions using image analysis. Note that full 3D analyses of the microstructures, based on X-Rays micro-computed tomography (Chateau et al, 2011), have shown that the variations of the pore sections along the fiber direction are small. They are neglected in the present study focused on the influence of the transverse geometry of the tows.…”

Section: Methodsmentioning

confidence: 99%

Micromechanical modeling of the elastic behavior of unidirectional CVI SiC/SiC composites

Chateau

Gélebart

Bornert

et al. 2015

International Journal of Solids and Structures

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International audienceThe elastic behavior of SiC/SiC composite is investigated at the scale of the tow through a micromechanical modeling taking into account the heterogeneous nature of the microstructure. The paper focuses on the sensitivity of transverse properties to the residual porosity resulting from the matrix infiltration process. The full analysis is presented stepwise, starting from the microstructural characterization to the study of the impact of pore shape and volume fraction. Various Volume Elements (VEs) of a virtual microstructure are randomly generated. Their microstructural properties are validated with respect to an experimental characterization based on high definition SEM observations of real materials, using various statistical descriptors. The linear elastic homogenization is performed using finite elements calculations for several VE sizes and boundary conditions. Important fluctuations of the apparent behavior, even for large VEs, reveal that scales are not separated. Nevertheless, a homogeneous equivalent behavior is estimated by averaging apparent behaviors of several VEs smaller than the Representative Volume Element (RVE). Therefore, the impact of the irregular shape of the pores on the overall properties is highlighted by comparison to a simpler cylindrical porous microstructure. Finally, different matrix infiltration qualities are simulated by several matrix thicknesses. A small increase in porosity volume fraction is shown to potentially lead to an important fall of transverse elastic moduli together with high stress concentrations

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In situ X-ray microtomography characterization of damage in SiCf/SiC minicomposites

Cited by 104 publications

References 40 publications

Influence of an O2 Type Oxidizing Environment on SiCf/SiC Composites: Properties/Microstructure Relationship

Influence of an O2 Type Oxidizing Environment on SiCf/SiC Composites: Properties/Microstructure Relationship

In situ damage mechanisms investigation of PA66/GF30 composite: Effect of relative humidity

Micromechanical modeling of the elastic behavior of unidirectional CVI SiC/SiC composites

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