Synthesis and characterisation of HIP Ca0.80Ce0.20ZrTi1.60Cr0.40O7 zirconolite and observations of the ceramic–canister interface

Blackburn, Lewis R.; Cole, Max R.; Gardner, Laura J.; Bailey, Daniel J.; Kuman, Merve; Mason, Amber R.; Sun, Shi‐Kuan; Maddrell, Ewan R.; Stennett, Martin C.; Corkhill, Claire L.; Hyatt, Neil C.

doi:10.1557/s43580-021-00055-8

Cited by 4 publications

(6 citation statements)

References 21 publications

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“…A Cr‐rich oxide layer of ∼10–20 μm (Figure 3) formed immediately adjacent to the HIP canister, as has been described previously 16,24 . Several EDS spot analyses were undertaken of this Cr‐rich oxide layer, and these showed varying contents of Al (2–5 at.%), Ti (2–8 at.%), Mn (0–8 at.%), Ni (0–5 at.%), and Fe (1–35 at.%).…”

Section: Resultssupporting

confidence: 61%

“…A Cr-rich oxide layer of ∼10-20 μm (Figure 3) formed immediately adjacent to the HIP canister, as has been described previously. 16,24 Several EDS spot analyses were undertaken of this Cr-rich oxide layer, and these showed varying contents of Al (2-5 at.%), Ti (2-8 at.%), Mn (0-8 at.%), Ni (0-5 at.%), and Fe (1-35 at.%). The oxide layer is attributed to the diffusion of Mn, Ni, Fe, and particu-larly Cr out of modified SS canister and subsequent reaction and oxidation by the HIPed material.…”

Section: Chromium-rich Oxidementioning

confidence: 99%

“…Scanning electron microscopy combined with energy‐dispersive X‐ray spectroscopy (SEM‐EDS) analysis detected small amounts of Cr or Fe as far as 500 μm into the wasteform, with Fe generally appearing to be more mobile. Recently, the interaction of an SS HIP canister with zirconolite 24 (nominal composition Ca 0.80 Ce 0.20 ZrTi 1.60 Cr 0.40 O 7 using Cr 3+ as a charge compensator) was inspected following HIPing. This study 24 observed, 5–8 μm of interaction region dominated by a Cr‐rich oxide layer and reported that minor Cr or Fe diffusion did not significantly destabilize the phase assemblage at the canister–ceramic wasteform interface.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the interaction of an SS HIP canister with zirconolite 24 (nominal composition Ca 0.80 Ce 0.20 ZrTi 1.60 Cr 0.40 O 7 using Cr 3+ as a charge compensator) was inspected following HIPing. This study 24 observed, 5–8 μm of interaction region dominated by a Cr‐rich oxide layer and reported that minor Cr or Fe diffusion did not significantly destabilize the phase assemblage at the canister–ceramic wasteform interface. However, the analyses described in the works earlier were undertaken focusing predominantly on the SS HIP canister material and using EDS line‐scans/mapping rather than providing a detailed profile of the elemental distribution within the interaction zone.…”

Section: Introductionmentioning

confidence: 99%

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Profiling hot isostatically pressed canister–wasteform interaction for Pu‐bearing zirconolite‐rich wasteforms

et al. 2022

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Zirconolite‐rich full ceramic wasteforms designed to immobilize Pu‐bearing wastes were produced via hot isostatic pressing (HIP) using stainless steel (SS) and nickel (Ni) HIP canisters. A detailed profiling of the elemental compositions of the major and minor phases over the canister–wasteform interaction zone was performed using scanning electron microscopy combined with energy‐dispersive X‐ray spectroscopy (SEM‐EDS) characterization. Bulk sample analyses from regions near the center of the HIP canister were also conducted for both samples using X‐ray diffraction and SEM‐EDS. The sample with the Ni HIP canister showed almost no interaction zone with only minor diffusion of Ni from the inner wall of the canister into the near‐surface region of the wasteform. The sample with the SS HIP canister showed ∼100–120 μm of interaction zone dominated by high‐temperature Cr diffusion from canister materials to the wasteform with the Cr predominantly incorporated into the durable zirconolite phase. We also examined, for the first time, changes to the HIP canister wall thickness caused by HIPing and demonstrated that no canister wall thinning occurred. Instead, in the areas examined, the canister wall thickness was observed to increase (up to ∼20%) due to the compression occurring during the HIP cycle. Further, only sparse formation of (Cr, Mn)‐rich oxide particles were noted within the HIP canister inner wall area immediately adjacent to the ceramic material, with no evidence for reverse diffusion of ceramic materials. Though the HIP canister–wasteform interaction extends to ∼120 μm when using an SS HIP canister for the system investigated, this translates to <<1 vol.% for an industrial scale HIPed wasteform. Importantly, the HIP canister–wasteform interactions did not produce any obviously less durable phases in the wasteform or had any detrimental impact on the HIP canister properties.

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Section: Resultssupporting

confidence: 61%

Section: Chromium-rich Oxidementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Profiling hot isostatically pressed canister–wasteform interaction for Pu‐bearing zirconolite‐rich wasteforms

et al. 2022

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“…Whilst the phase assemblage, density and microstructural properties of zirconolite ceramics, as a function of dopants and processing conditions, has been widely studied across a variety of discrete compositions, many samples produced by this sintering route retain moderate porosity [13][14][15]. Pressure-assisted sintering routes such as hot isostatic pressing (HIP) have been proposed as alternative processing routes due to an existing knowledge base from industrial practices [16][17][18]. A promising route to improve the densification and optimise the thermal processing cycle of wasteform materials is the use of sintering aid additives.…”

Section: Introductionmentioning

confidence: 99%

Process Development of Zirconolite Ceramics for Pu Disposition: Use of a CuO Sintering Aid

et al. 2023

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Zirconolite-structured ceramics are candidate wasteform materials for the immobilisation of separated Pu. Due to the refractory properties of zirconolite and other titanates, removing residual porosity remains challenging in the final wasteform product when utilising a conventional solid state sintering route. Herein, we demonstrate that the addition of CuO as a sintering aid increases densification and promotes grain growth. Moreover, zirconolite phase formation was enhanced at lower process temperatures than typically required (≥1350 °C). CuO addition allowed an equivalent density to be reached using process temperatures of 250 °C lower than the undoped composition. At 150 °C lower than the undoped zirconolite, the addition of CuO resulted in a favourable microstructure and phase assemblage, as confirmed via X-ray diffraction and scanning electron microscopy. Secondary phases of CaTiO3 and Ca0.25Cu0.75TiO3 were observed at some processing temperatures, which may prove deleterious to wasteform performance. The use of a CuO sintering aid provides an avenue for the further development of the thermal processing of ceramic wasteform materials.

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Characterisation of hot isostatically pressed (HIPed) hollandite wasteform-canister interaction zone

Mann,

Farzana,

Aughterson

et al. 2024

Journal of Nuclear Materials

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Synthesis and characterisation of HIP Ca0.80Ce0.20ZrTi1.60Cr0.40O7 zirconolite and observations of the ceramic–canister interface

Cited by 4 publications

References 21 publications

Profiling hot isostatically pressed canister–wasteform interaction for Pu‐bearing zirconolite‐rich wasteforms

Profiling hot isostatically pressed canister–wasteform interaction for Pu‐bearing zirconolite‐rich wasteforms

Process Development of Zirconolite Ceramics for Pu Disposition: Use of a CuO Sintering Aid

Characterisation of hot isostatically pressed (HIPed) hollandite wasteform-canister interaction zone

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