Effect of Sintering Process on Densification of UN-30%U3Si2 Pellets
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摘要: 本文基于粉末冶金技术制备了UN-30%U3Si2复合燃料芯块（U3Si2质量百分数为30%），研究了烧结气氛、烧结温度、烧结时间等烧结工艺对芯块烧结密度的影响规律，主要通过芯块的化学成分、物相组成以及微观组织变化等方面进行致密化过程分析。结果表明，UN-30%U3Si2复合燃料芯块真空烧结相比氩气气氛烧结更有利于致密化；随着烧结温度（1600~1675℃）升高，致密度逐渐增加，最高可达97%T.D.（T.D.为理论密度）；当烧结温度高于U3Si2熔点之后，随着温度上升，U3Si2相在高真空条件下会烧损挥发，并且N元素有向U3Si2相扩散的趋势，形成未知USixNy相；烧结温度的升高或者烧结时间的延长，均有利于U3Si2相对UN相形成包覆。
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关键词:
- UN-30%U3Si2复合燃料 /
- 烧结工艺 /
- 致密化过程
Abstract: In this paper, UN-30%U3Si2 composite fuel pellets with 30wt.%U3Si2 content were prepared based on powder metallurgy technology. The influence of sintering atmosphere, sintering temperature, sintering time and other sintering processes on the sintering density of pellets was studied. The densification process was analyzed mainly through the chemical composition, phase composition and microstructure changes of pellets. The results show that vacuum sintering of UN-30%U3Si2 composite fuel pellets is more favorable to densification than argon atmosphere sintering. With the increase of sintering temperature (1600~1675°C), the density increases gradually, up to 97%T.D. When the sintering temperature is higher than the melting point of U3Si2, with the increase of temperature, the U3Si2 phase suffers losses and volatilization during the high vacuum sintering process, and the N element tends to diffuse to the U3Si2 phase, forming the unknown USixNy phase. The increase of sintering temperature or the extension of sintering time is conducive to the formation of coating of U3Si2 relative to UN phase.-
Key words:
- UN-30%U3Si2 composite fuel /
- Sintering process /
- Densification process
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图 1 UN粉末XRD图谱
PDF#xx-xxxx—标准衍射卡片编号；2θ—衍射角度
Figure 1. X-ray Diffraction Pattern of UN Powder
图 4 UN-30%U3Si2复合燃料芯块烧结工艺制度
Figure 4. Sintering Process System of UN-30%U3Si2 Composite Fuel Pellets
图 5 1650℃烧结UN-30%U3Si2复合芯块的微观形貌对比
Figure 5. Comparison of Microstructure of UN-30%U3Si2 Composite Pellets Sintered at 1650°C
图 6 1650℃真空烧结UN-30%U3Si2复合芯块的形貌与背散射结果
Figure 6. Morphology and Backscattering Results of Sintered Composite Pellets in Vacuum at 1650°C
图 7 UN-30%U3Si2复合芯块烧结密度随温度变化规律
Figure 7. Variation of Sintering Density of UN-30%U3Si2 Composite Pellets with Temperature
图 8 不同烧结温度下UN-30%U3Si2复合芯块的SEM形貌照片
Figure 8. SEM Morphology Photos of UN-30%U3Si2 Composite Pellets at Different Sintering Temperatures
图 9 不同烧结温度下UN-30%U3Si2复合芯块的气孔直径变化趋势
Figure 9. Variation Trend of Porosity of UN-30%U3Si2 Composite Pellets at Different Sintering Temperatures
图 10 不同温度下UN-30%U3Si2复合芯块的XRD图谱
Figure 10. X-ray Diffraction Patterns of Sintered UN-30%U3Si2 Composite Pellets at Different Temperatures
图 11 1700℃烧结不同时间的UN-30%U3Si2复合芯块密度变化趋势
Figure 11. Density Variation Trend of N-30%U3Si2 Composite Pellets with Different Sintering Times at 1700°C
图 12 1700℃烧结4 h的UN-30%U3Si2复合芯块边缘金相照片
Figure 12. Metallographic Photo of 30%U3Si2 Composite Pellet Edge Sintered at 1700°C for 4 h
图 13 1700℃下分别烧结1 h、4 h后UN-30%U3Si2复合芯块SEM图片
Figure 13. SEM of 30%U3Si2 Composite Pellets Sintered at 1700°C for 1 h and 4 h Respectively
表 1 真空、氩气气氛烧结UN-30%U3Si2复合芯块的元素含量（1650℃）
Table 1. Elemental Content of Sintered UN-30%U3Si2 Composite Pellets in Vacuum and Argon Atmosphere (1650°C)
烧结条件 元素质量百分数/% U N Si C O 真空 92.09 4.80 2.10 0.16 0.81 氩气 92.33 4.20 2.06 0.22 1.00 
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点 元素质量百分数/% U N Si O EDS Spot 1 84.14 12.73 0 3.13 EDS Spot 2 75.19 3.74 16.16 4.91 EDS Spot 3 82.34 9.96 0 7.70
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表 3 不同烧结温度下UN-30%U3Si2复合芯块的Si、U含量
Table 3. Si and U Contents of UN-30%U3Si2 Composite Pellets at Different Sintering Temperatures
元素 质量百分数/% 1600℃ 1625℃ 1650℃ 1675℃ 1700℃ 1725℃ Si 2.22 2.17 2.18 2.10 1.81 0.97 U 92.06 92.33 91.17 92.09 92.47 93.17
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表 4 1700℃烧结不同时间UN-30%U3Si2复合芯块的Si、U含量
Table 4. Si and U Contents of 30%U3Si2 Composite Pellets Sintered at 1700°C for Different Time
元素 质量百分数/% 1 h 2 h 3 h 4 h Si 1.90 1.81 1.95 2.00 U 91.22 92.47 92.23 92.50
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