Effect of residual carbon on the sintering behavior of MOX pellets

None

朝倉 浩一; 武内 健太郎 

Asakura, Koichi; Takeuchi, Kentaro

MOX燃料ペレットの焼結挙動への残留炭素の影響を研究するため、異なる量の炭素(2901735ppm)を含むMOXペレットの焼結挙動を10732023Kの温度範囲で調査した。加熱中の試料の収縮は非接触型のディラトメータで測定した。高炭素残留濃度の2試料は、低残留炭素濃度2試料と比較し、12731523Kの温度範囲において約6倍の収縮を示した。この挙動は、高残留炭素濃度試料においては、COガスの生成によりO/Mが低下し、結果として金属イオンの相互拡散係数が大きく増加したと考えることに理解できる。低残留炭素濃度試料では、COガスの生成量が小さいため、相互拡散係数には影響しない。2種類の試料における収縮挙動の違いは、セラミックスの初期焼結段階に適用される理論モデルからも議論されている。

Sintering behavior of MOX compacts containing defferent amounts of carbon (290 to 1,735 ppm) was investigated at temperatures from 1,073 to 2,023 K to study the effect of residual carbon. Specimen shrinkages were measured with a non-contact type optical dilatmeter during heating. The compact shrinkage from 1,273 to 1,523 K was about 6 times larger in the two spcimens with high residual carbon content than in the two specimens with low residual content. This behavior could be understood by considering that shrinkage of former specimens was enhanced in this temperature range by the decrease of O/M ratio due to the evolution of CO gas and consequently the significant increase of the metal ion inter-diffusion conefficient. In the specimens with low residual carbon content, the amount of CO gas evolution was too small to affect the inter-diffusion coefficient. This differece in shrinkage between the two kinds of specimens was also discussed from a theoretical model applied to the initial sintering stage of ceramics.