On Morphological and Microstructural Changes in Uranium Dioxide Powder during Binder-Free Hot Pressing

Plasticity of oxide fuel based on uranium dioxide is one of the less-covered topics in nuclear materials science. A useful tool to study the deformation mechanisms in this material at elevated temperatures is hot pressing. In this work, UO$_{2.06}$ powder prepared via~ADU route was uniaxially compacted at temperatures within the~$250$--$600$~{\textdegree}C range under a compressive axial stress from~$95$ to~$220$~MPa applied for a time interval between~$10$ and~$60$~min. Examinations performed with scanning electron microscopy~(SEM) and density measurements revealed a temperature effect on densification when increasing the compaction temperature from~$400$ to~$600$~\textdegree{C} with other conditions being equal. By varying the loading duration for hot pressing at~$600$~{\textdegree}C under constant compressive stress~$95$~MPa, different stages of compactions were analyzed. In addition,~XRD measurements revealed a texture developing in the material during compaction and a possible increase in dislocation density. It is argumented that dislocation-mediated plasticity contributes to densification at elevated temperatures.

[1]  D. Siegele,et al.  Cleavage fracture assessment of transient thermo-mechanical loading situations by local approach , 2017 .

[2]  A. Lunev,et al.  Glide mobility of the 1/2[1 1 0](0 0 1) edge dislocation in UO2 from molecular dynamics simulation , 2017 .

[3]  M. Isaenkova,et al.  Express method of construction of accurate inverse pole figures , 2016 .

[4]  V. G. Baranov,et al.  An attempt to reproduce high burn-up structure by ion irradiation of SIMFUEL , 2014 .

[5]  M. Isaenkova,et al.  The Role of Residual Elastic Stress in Shrinkage of Cold-Pressed and Sintered Fuel Tablets , 2014 .

[6]  J. Crocombette,et al.  Diffusion model of the non-stoichiometric uranium dioxide , 2013 .

[7]  G. Delette,et al.  Green strength of binder-free ceramics , 2013 .

[8]  V. G. Baranov,et al.  Sintering particulars of pelletized oxide nuclear fuel , 2011 .

[9]  J. Halloran,et al.  Compaction Behavior of Spray-Dried Alumina , 2006 .

[10]  S. L. Rough,et al.  The effects of wall friction in powder compaction , 1998 .

[11]  I. Uslu,et al.  Powder characteristics and microstructure of uranium dioxide and uranium dioxide-gadolinium oxide fuel , 1996 .

[12]  G. Briggs,et al.  Scanning tunneling microscopy of the UO2 (111) surface , 1996 .

[13]  Huang Ching-Tsven.  Dry-ADU process for UO2 production , 1992 .

[14]  A. Heuer,et al.  Plastic deformation in nonstoichiometric UO2+x single crystals. I: Deformation at low temperatures , 1988 .

[15]  Pan Yi-ming,et al.  The conversion of UO2 via ammonium uranyl carbonate: Study of precipitation, chemical variation and powder properties , 1981 .

[16]  R. Delhez,et al.  The elimination of an approximation in the Warren–Averbach analysis , 1976 .

[17]  J. Marin,et al.  Uranium and oxygen self-diffusion in UO2 , 1969 .

[18]  I. Amato,et al.  Hot-pressing of uranium dioxide , 1966 .

[19]  Robert L. Coble,et al.  A Model for Boundary Diffusion Controlled Creep in Polycrystalline Materials , 1963 .

[20]  C. Ang,et al.  Sintering of high density uranium dioxide bodies , 1960 .

[21]  B. Warren,et al.  The Effect of Cold‐Work Distortion on X‐Ray Patterns , 1950 .

[22]  V. G. Baranov,et al.  Sintering of oxide nuclear fuel: Plastic flow mechanism , 2013 .

[23]  T. Abe,et al.  2.15 – Uranium Oxide and MOX Production , 2012 .

[24]  P. Balakrishna,et al.  Light attrition of uranium dioxide powder , 2003 .

[25]  R. Crawford,et al.  Solid phase compaction of polymeric powders: effects of compaction conditions on pressure and density variations , 1982 .