Anisotropy analysis of ultra-fine grain graphite and pyrolytic carbon

Campbell, Anne A.; Campbell, K. B.; Was, Gary S.

doi:10.1016/j.carbon.2013.04.054

Cited by 17 publications

(6 citation statements)

References 20 publications

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“…The derivation of the relationship between φ and g is not included here and any reader requiring further detail should consult reference. 62 Using pole intensity data such as that shown in Fig. 13b, Sutton and Howard 48 defined the relationship between bulk CTE and crystal CTE using the following relationship:…”

Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

“…To help the reader understand the basis of the Bacon 46 techniques used by Sutton and Howard 48 the experimental technique is briefly outlined below. However the reader is encouraged to refer to a recent paper by Campbell 62 which describes the experimental technique and method of analysis in detail.…”

Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

“…The derivation of the relationship between φ and is not included here and any reader requiring further detail should consult reference. 62

Figure 13 Experimental setup and typical output used to determine the Bacon Anisotropy Factor (BAF) in graphite. a Transmission XRD experimental set up due to Campbell.…”

Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

“…a Transmission XRD experimental set up due to Campbell. 62 b Typical [0002] pole intensity data for PGA graphite, 0–90 o shown as a function of dispersion angle . This is repeated as a sinusoid pattern around the 360 o …”

Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

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Dimensional change, irradiation creep and thermal/mechanical property changes in nuclear graphite

Marsden

Haverty

Bodel

et al. 2016

International Materials Reviews

106

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Since the start of the 'nuclear age' graphite has been employed as a moderator in around 100 nuclear reactors, and today there are still some 30 graphite-moderated reactors operating and there are plans for new Generation IV high-temperature reactors. Many of the graphite moderator reactors now producing power are operating beyond their original design life. Therefore in some cases, to aid the reactor operators and designers, the existing graphite irradiation databases need to be extended either to a higher temperature or higher neutron fluence. Furthermore, data are needed for the different grades of graphite that are available at present. This can either be achieved by expensive, time consuming irradiation programmes or by improving the understanding of the mechanisms and processes which lead to irradiationinduced dimensional and property changes in the graphite core components. This review looks at three of the most important graphite properties which change with exposure to irradiation, namely dimensional change, irradiation creep and thermal expansion. The behaviour of UK AGR, Magnox and an experimental grade of German reactor graphite are explored in some detail. First graphite reactor core design is briefly discussed, giving examples of typical graphite components and core arrangements. Issues related to aging graphite component and core behaviour are illustrated through examples of component internal and thermal stress generation, and issues related to whole core behaviour are also outlined. Second the manufacture and microstructure of different nuclear graphite grades are discussed, highlighting how the choice of raw materials and manufacturing technique influences the graphite properties. Third the coefficient of thermal expansion, dimensional change and irradiation creep are analysed using microstructural and averaging methods which are used to relate crystal to bulk properties by accounting for graphite crystal orientation and porosity. These techniques, which were first applied to nuclear graphite in the 1960s, are extended and discussed with the aim of trying to lend some understanding to the role the microstructural crystallite and porosity distributions play in defining the dimensional stability and properties of virgin graphite, irradiated graphite and stressed graphite.

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Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

“…The derivation of the relationship between φ and is not included here and any reader requiring further detail should consult reference. 62

Figure 13 Experimental setup and typical output used to determine the Bacon Anisotropy Factor (BAF) in graphite. a Transmission XRD experimental set up due to Campbell.…”

Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

Section: Averaging Porosity and Orientation Relationshipsmentioning

confidence: 99%

See 2 more Smart Citations

Dimensional change, irradiation creep and thermal/mechanical property changes in nuclear graphite

Marsden

Haverty

Bodel

et al. 2016

International Materials Reviews

106

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“…Unirradiated and irradiated Gilsocarbon graphites were machined into plates with l × w × d dimensions of 18 × 8 × 3 mm and a 2.8 mm hole at the centre. The anisotropic properties of Gilsocarbon (1:1.1 ratio as defined by the with and against grain coefficient of thermal expansion ratio in unirradiated graphite), caused by the preferential orientation of crystallite domains and aligned micro/nano-cracks perpendicular to the moulding/pressing (along the billets main axis) direction [38,39], means that the direction of machining requires careful consideration. In order to minimise potential mechanical performance differences resulting from bias within the graphite brick, all samples were machined such that the l × w × d of the plates equated to cuts in the graphite billet axial, radial and azimuth directions, see Fig.…”

mentioning

confidence: 99%

4D synchrotron X-ray microtomography of fracture in nuclear graphite after neutron irradiation and radiolytic oxidation

Wade-Zhu

Krishna

Bodey

et al. 2020

Carbon

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Herein, the first study is presented using 4D synchrotron X-ray microtomography to capture all stages of crack development in neutron irradiated and radiolytically oxidised nuclear graphite.Employing a novel loading setup, specimens of Gilsocarbon graphite, both unirradiated and irradiated at 301 °C to 19.7 x 1020 neutrons/cm2 (~2.6 displacements/atom (dpa)), were loaded to generate a crack.All stages of the fracture process were then captured using synchrotron X-ray imaging. Reconstructed tomographic images and 3D segmented crack volumes have been used to observe and analyse the irradiation-induced evolution of the graphite microstructure as well as corresponding changes in the crack initiation, propagation, and arrest behaviour of graphite after neutron irradiation. Close examination of the applied stress-strain curves highlights the suppression of micro-crack-based damage accumulation in irradiated graphite. Moreover, as well as the crack-bridging and deflection mechanisms characteristic of unirradiated graphite, crack arrest in the irradiated graphite is shown to be significantly influenced by crack tip blunting. This change is associated with the growth of the open pore structure of graphite, specifically the enlargement and increased frequency of macro-pores, resulting from the simultaneous radiolytic oxidation of the graphite microstructure during neutron irradiation.

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Emulating Neutron Irradiation Effects with Ions

Was

2016

Fundamentals of Radiation Materials Science

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Anisotropy analysis of ultra-fine grain graphite and pyrolytic carbon

Cited by 17 publications

References 20 publications

Dimensional change, irradiation creep and thermal/mechanical property changes in nuclear graphite

Dimensional change, irradiation creep and thermal/mechanical property changes in nuclear graphite

4D synchrotron X-ray microtomography of fracture in nuclear graphite after neutron irradiation and radiolytic oxidation

Emulating Neutron Irradiation Effects with Ions

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