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dc.rights.licenseRestricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.
dc.contributorLian, Jie
dc.contributorBorca-Tasçiuc, Theodorian
dc.contributorLiu, Li (Emily)
dc.contributorHe, Xiaozheng (Sean)
dc.contributor.authorWang, Yachun
dc.date.accessioned2021-11-03T09:22:15Z
dc.date.available2021-11-03T09:22:15Z
dc.date.created2021-02-22T15:32:44Z
dc.date.issued2020-08
dc.identifier.urihttps://hdl.handle.net/20.500.13015/2622
dc.descriptionAugust 2020
dc.descriptionSchool of Engineering
dc.description.abstractThe corrosion interactions between a metallic canister material, stainless steel 316, and IAPT ceramic in a chloride solution was explored. Crevice corrosion of the SS in close proximity to the IAPT resulted in the development of an aggressive environment at the interface of the two materials, which was acidic and enriched in Cl− anions. The enrichment of Cl− anions within the occluded crevice space as the result of SS crevice corrosion drastically enhanced the corrosion of IAPT. The release of radioactive iodine from this apatite waste form could be accelerated owing to this mechanism. This is evidenced by a substantial depletion of iodine from the I-APT matrix and a large amount of Cl-bearing precipitates on the surfaces of both SS and I-APT. On the other hand, the corrosion of IAPT leads to the precipitation of a V- and Pb-rich layer, which inhibits the localized corrosion of SS to an extent. This study reveals a new near-field corrosion mechanism for ceramic waste forms when they are exposed to aggressive local conditions created by the electrochemical reactions of nearby metals. This study advances the understanding of the near-field corrosion interactions between metallic canisters and ceramic waste forms and could be beneficial for a more accurate prediction of waste form degradation.
dc.description.abstractEnvironmental induced material degradation is a big challenge in nuclear industry. The safe and effective management and disposal of nuclear waste has become a critical issue in the development of nuclear energy. Neutron irradiation induced mechanical property degradation in critical structural component nuclear reactors has raised up safe operation concerns when facing the extension of service life for the currently in-service nuclear power plants. In the present dissertation, towards understanding the environmental durability and degradation mechanism of ceramic (apatite and perovskite ceramic material) and metallic (stainless steel 316 and X-750 superalloy) materials used in nuclear industry, a series of comprehensive investigation was conducted.
dc.description.abstractGrain boundaries (GBs), known as two-dimensional defects, are omnipresent in metallic polycrystalline alloys and then influence a wide range of mechanical properties under different environmental conditions like irradiation and corrosion. In order to quantify the grain boundary strength for neutron irradiated X-750 alloy, a site-specific grain boundary was extracted and fabricated into micro-tensile specimens and further tested by using an in-situ push-to-pull (PTP) method in the FIB/SEM system. The micro-tensile specimen fabrication method guarantees that the grain boundary plane is nearly perpendicular to the tensile direction, expecting to greatly benefit the development of grain boundary strength measurement at micro or nano scale in a wide scope of materials. The neutron irradiated high grain boundary was tested to have comparable ultimate tensile strength as that of non-irradiated sample, while the former one gave a slightly reduced ductility in comparison to the latter sample, showing the irradiation-induced embrittlement.
dc.description.abstractCs2SnCl6 ceramic material holds promise as a potential nuclear waste form due to its high mass loadings of problematic radionuclide Cl. In this work, a concept of artificial passivation was applied by depositing a protective TiO2 coating of 10 nm thick on the surface of Cs2SnCl6 perovskite in order to enhance its water stability in aqueous environments. The water/environmental stability of Cs2SnCl6 can be enhanced by the artificially-coated TiO2 passivation film in the initial short term. An amorphous-to-crystalline phase transition occurs in the passivation film, possibly leading to degradation of the water stability in Cs2SnCl6. Mechanical degradation of the TiO2 passivation film occurs upon a cyclic hydration-dehydration process during semi-dynamic leaching testing, resulting in film breakdown and increased elemental release. Fine control of the structure/interaction of the artificial passivation with materials matrix and environment is necessary to mitigate the potential structural, chemical and mechanical degradation and thus further improve materials’ environmental stability and chemical durability.
dc.description.abstractThe degradation mechanism of a potential ceramic waste material, lead-vanado-iodoapatite (IAPT, Pb9.85(VO4)6I1.7), in NaCl solutions at 90 ºC was investigated through systematic characterization of surface morphology, microstructure, and microchemistry evolution of the alteration layer. Nano-scale characterization indicated that IAPT crystals degraded from grain boundaries toward inner grains, forming ultrafine Cl-bearing crystallites. A coupled interface dissolution-reprecipitation replacement mechanism and the ion exchange between Cl− and I− across the degradation zone may together play roles in determining the nano-scale degradation behavior of IAPT. This work highlights the degradation through multiple reactions and elemental transport across the liquid-solid and solid-solid interfaces at length scales from sub-millimeter to nanoscale.
dc.language.isoENG
dc.publisherRensselaer Polytechnic Institute, Troy, NY
dc.relation.ispartofRensselaer Theses and Dissertations Online Collection
dc.subjectNuclear engineering
dc.titleInterfacial degradation of ceramic and metallic materials under corrosion and irradiation conditions
dc.typeElectronic thesis
dc.typeThesis
dc.digitool.pid180360
dc.digitool.pid180361
dc.digitool.pid180362
dc.rights.holderThis electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
dc.description.degreePhD
dc.relation.departmentDept. of Mechanical, Aerospace, and Nuclear Engineering


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