Effect of intermolecular and electrostatic cohesive forces on the process of densification of particulate materials

Grechka, V. D.

doi:10.1007/bf00791774

Cited by 2 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considering the density of the green bodies, one can assume that such dehydration could occur through open porosity without generating any additional defects, such as cracks and pores, in the pellet. On the contrary, dehydration could enhance the aggregation then the packing of the powder, leading to the densification of the agglomerates through electrostatic processes [38].…”

Section: Sintering Of Uranium-cerium Hydrated Oxidesmentioning

confidence: 99%

An original precipitation route toward the preparation and the sintering of highly reactive uranium cerium dioxide powders

Martinez

Clavier

Mesbah

et al. 2015

Journal of Nuclear Materials

View full text Add to dashboard Cite

h i g h l i g h t sDense (U,Ce)O 2 pellets were prepared from highly reactive precursors. Nanosized hydrated oxides were first obtained through precipitation route. Direct sintering was performed by heating between 1350°C and 1550°C. Microstructures composed of dense materials with submicrometric grains were achieved. a b s t r a c tThe preparation of dense U 1Àx Ce x O 2 mixed dioxides pellets was achieved from the initial precipitation of highly reactive precursors. In a first step, a wet chemistry route, based on the mixture of U 4+ and Ce 4+ in acidic solution with large excess of NH 4 OH, was set up to reach the precipitation of the cations. The solid phase was then dried under vacuum to avoid aggregation phenomena. Further characterization of the powders by XRD, EDS and TEM revealed the formation of hydrated U 1Àx Ce x O 2 ÁnH 2 O that probably resulted from the aging of hydroxide compounds. Also, microscopy investigations evidenced the nanosized character of the powder which was associated to high values of specific surface area, typically in the 100-150 m 2 g À1 range.The behavior of U 1Àx Ce x O 2 ÁnH 2 O versus temperature was investigated in a second part. If the increase of the heat temperature allowed one to observe an improvement of the crystallization state linked with the growth of crystallites, it was also accompanied by a strong decrease of the powders reactivity. On this basis, sintering tests were conducted in reducing atmosphere on the compounds as prepared. Dilatometry experiments indicated a low densification temperature compared to other ways of preparation reported in the literature. Also, the pellets prepared after firing at different temperatures (1350-1550°C) showed that a wide range of microstructures was achievable. Particularly, bulk materials with densities of 90-95% of the calculated value could be prepared with average grain size ranging from around 100 nm to more than 5 lm. This simple process of elaboration of dense materials from highly reactive hydrated oxide precursor thus appears as a very interesting way to prepare actinide oxides materials.

show abstract

Section: Sintering Of Uranium-cerium Hydrated Oxidesmentioning

confidence: 99%