Implementation of a spark plasma sintering facility in a hermetic glovebox for compaction of toxic, radiotoxic, and air sensitive materials

Abstract

Spark plasma sintering (SPS) is a rapidly developing method for densification of powders into compacts. It belongs to the so-called “field assisted sintering techniques” that enable rapid sintering at much lower temperatures than the classical approaches of pressureless sintering of green pellets or hot isostatic pressing. In this paper, we report the successful integration of a SPS device into a hermetic glovebox for the handling of highly radioactive material containing radioisotopes of U, Th, Pu, Np, and Am. The glovebox implantation has been facilitated by the replacement of the hydraulic system to apply pressure with a compact electromechanical unit. The facility has been successfully tested using UO2 powder. Pellets with 97% of the theoretical density were obtained at 1000 °C for 5 min, significantly lower than the ∼1600 °C for 5-10 h used in conventional pellet sintering.

From uranium(IV) oxalate to sintered UO 2 : Consequences of the powders' thermal history on the microstructure

“…2). Such amount would correspond to less than 3.8 wt.% of CO 3 entities, which appears to be in very good agreement with the recent values reported by Tyrpekl et al during the study of uranium(IV) and thorium(IV) nanograined oxalates (i.e., <3.4 wt.% of carbonate) [38]. Nevertheless, the heat treatments combining the use of oxidizing and reducing atmospheres appeared to be much more efficient to operate the carbon elimination.…”

On the Role of the Electrical Field in Spark Plasma Sintering of UO2+x

“…Spark plasma sintering was conducted in an SPS (FCT Systeme GmbH, Rauenstein, Germany) installed in a glovebox for handling radioactive substances6. Both glovebox and SPS chamber were kept under Ar atmosphere.…”

“…Although SPS is now a common tool in materials research, its application to nuclear fuels has not been explored extensively, possibly due to complexity associated with the safe handling of actinides. Recent research in Electric Field Assisted Sintering (EFAS) of actinide oxides and nitrides has shown the great potential of the technique, but has also evidenced the need for a better understanding of the behaviour of actinides during EFAS67891011121314. Uranium oxide, due to its multiple oxidation states and electrical characteristics, is an ideal model material to investigate some of the peculiar effects of the electric field in the processing of ceramic materials.…”

Synthesis of nanostructured ThO2 pellets

“…The powders were compacted in a small‐sized SPS (FCT Systeme GmbH) integrated in a glovebox for the handling of radioactive materials . Sintering was performed under vacuum with 50/5 ms current/pause intervals.…”