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EBSD studies on microstructure and crystallographic orientation of UO 2-Mo composite fuels
Murali Krishna Tummalapalli,Jerzy A. Szpunar,Anil Prasad,Lukas Bichler 한국원자력학회 2021 Nuclear Engineering and Technology Vol.53 No.12
The microstructure of the fuel pellet plays an essential role in fission gas buildup and release and iscritical for the safe and continued operation of nuclear power stations. Structural analysis of uraniumdioxide (UO2)emolybdenum (Mo) composite fuel pellets prepared at a range of sintering temperaturesfrom 1300 to 1800 C was performed. Mo micro and nanoparticles were used in making the compositepellets. A systematic investigation into the influence of processing parameters during Spark PlasmaSintering (SPS) of the pellets on the microstructure, texture, grain size, and grain boundary characters ofUO2-Mo is presented. UO2-Mo composite show significant differences in the fraction of generalboundaries and also special/coincident site lattice (CSL) boundaries. EBSD orientation maps demonstrated that <111> texturing was observed in the pellets fabricated at 1500 C. The experimental investigations suggest that UO2-Mo composite pellets have favorable microstructural features compared tothe UO2 pellet.
Estimation and validation of maxwell stress of planar dielectric elastomer actuators
Raj Kumar Sahu,Abhishek Saini,Dilshad Ahmad,Karali Patra,Jerzy Szpunar 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1
In this paper, Maxwell stress of circular planar actuator at different applied voltages was estimated and then validated with the uniaxialcompression test of three different dielectric elastomers (VHB, silicone and natural rubber). Pelrine’s equation was revisited to estimateMaxwell stress which causes the actuation in the planar direction. More precise and accurate estimation of Maxwell stress could be madein this work by considering variation of dielectric constant with respect to frequency and pre-strain. Estimated Maxwell stress was validatedthrough (i) out-of-plane strain or thickness strain obtained from measured area strain considering constant volume deformation, and(ii) out-of-plane mechanical compressive test results. The estimated Maxwell stress agrees well with the corresponding experimentalcompressive stress values for different pre-straining cases considered in this work.
Textural Evaluation of Al–Si–Cu Alloy Processed by Route BC-ECAP
Esmaeil Damavandi,Salman Nourouzi,Sayed Mahmood Rabiee,Roohollah Jamaati,Jerzy A. Szpunar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8
In this study, route Bc of the equal channel angular pressing (ECAP) method has been successfully applied to the Al–Si–Cualloy at 400 °C. Scanning electron microscopy (SEM) and electron backscatter difraction (EBSD) were used to analyze themicrostructure. Texture evolution was studied by the X-ray difraction (XRD) technique. The microstructural results showedthat at least four passes of route BC need to access uniform distribution of fne intermetallic compounds (IMCs) and eutecticsilicon particles (ESPs). The particle stimulated nucleation (PSN) and continuous dynamic recrystallization (CDRX) aretwo important mechanisms to refne the aluminum matrix in Al–Si–Cu alloy. The texture results revealed that owing to achange in the rotation direction of route BC in consecutive passes, this process led to creating diferent types of textures, inboth qualitative and quantitative senses. The A*1Ѳ and A*2Ѳ were the strongest texture components after the fourth pass ofroute BC. Regardless of route A, the route BC-ECAP process led to strengthen the {100}⟨001⟩ and {011}⟨100⟩ componentsand weaken the {001}⟨310⟩ component. Three components, {100}⟨110⟩, {021}⟨501⟩, and {013}⟨313⟩ were developed byroute BC. The efects of route BC on texture homogeneity were also studied.
Malakkal Linu,Prasad Anil,Ranasinghe Jayangani,Jossou Ericmoore,Bichler Lukas,Szpunar Jerzy 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.10
Thorium dioxide (ThO2)-silicon carbide (SiC) composite fuel pellets were fabricated via the spark plasmasintering (SPS) method to investigate the role of the addition of SiC in enhancing the thermal conductivity of ThO2 fuel. SiC particles with an average size of 1mm in 10 and 15 vol% were used to manufacture the composite pellets. The changes in the composites' densification, microstructure and thermal conductivity were explored by comparing them with pure ThO2 pellets. The structural and microstructural characterization of the composite pellets has revealed that SPS could manufacture high-quality composite pellets without having any reaction products or intermetallic. The density measurement by the Archimedes principles and the grain size from the electron back-scattered diffraction (EBSD) analysis has indicated that the composites have higher densities and smaller grain sizes than the pellets without SiC addition. Finally, thermal conductivity as a function of temperature has revealed that sintered ThO2eSiC composites showed an increase of up to 56% in thermal conductivity compared to pristine ThO2 pellets