热顶设计对高纯钆铸造靶材缺陷影响的数值模拟研究  

Simulation-based Analysis on Impact of Hot Top Design on Defects in High Purity Gadolinium Casting Targets

作　　者：张永健 ZHANG Yongjian(Fujian Golden Dragon Rare-earth Co.,Ltd.,Fujian Longyan 366309,China;Fujian Enterprise Engineering Technology Research Center for Functional Rare Earth Materials,Fujian Longyan 366309,China)

机构地区：[1]福建省金龙稀土股份有限公司,福建龙岩366309 [2]福建省稀土功能材料企业工程技术研究中心,福建龙岩366309

出　　处：《精密成形工程》2025年第2期167-175,共9页Journal of Netshape Forming Engineering

摘　　要：目的研究热顶设计对凝固过程中高纯稀土钆(Gd)铸造靶材温度分布及铸造缺陷分布的影响,通过优化热顶结构增强液体凝固时的补缩能力,降低高纯稀土Gd铸造靶材出现内部缺陷的概率。方法以铸锭尺寸137 mm×126 mm×190 mm的高纯稀土Gd铸造靶材为研究对象,利用有限元软件Procast对高纯Gd铸锭真空模铸过程进行数值模拟,研究热顶直段高度及热顶材质对Gd铸锭凝固时温度与缺陷分布的影响。结果数值模拟结果表明,热顶结构能够对熔体上层起到保温效果,改变了熔体整体的温度分布情况,强化了熔体自下而上的凝固行为,使缺陷位置上移,缺陷体积减小。当使用氧化镁作为热顶材料时,最佳热顶高度为60 mm,此时Gd铸锭中的缺陷体积最小,为9.4 cm^(3);当使用莫来石作为热顶材料时,最佳热顶高度为50 mm,此时Gd铸锭中的缩孔体积最小,为9.1 cm^(3)。结论热顶结构对高纯稀土Gd铸造靶材的凝固过程产生了显著的影响,延缓了铸模内上层熔体的凝固,因此增强了液相补缩能力,使铸造缺陷位置上升、体积减小。不同的热顶材质保温效果存在差异,相比于氧化镁,莫来石热顶的保温效果更好。The work aims to study the effect of hot top design on temperature distribution and casting defect distribution of high purity gadolinium(Gd)casting targets,enhance the feeding ability of liquid by improving the hot top structure,and reduce the probability of internal defects in high purity Gd casting targets.Taking a high purity rare earth Gd casting target with an in-got size of 137 mm×126 mm×190 mm as the research object,the numerical simulation of the vacuum casting process of the high purity Gd ingot was carried out by finite element software Procast,and the impact of the height of the hot top straight section and the hot top material on the temperature and defect distribution during the solidification of the Gd ingot was studied.The numerical simulation results showed that the hot top structure could insulate the upper layer of the melt,so it affected the overall temperature distribution of the melt,strengthened the solidification behavior of the melt from bottom to top,and made the defect position move up and the defect volume decrease.When magnesium oxide was used as hot top material,the optimum hot top height was 60 mm,and the defect volume in the Gd ingot was the smallest,which was 9.4 cm^(3);When mullite was used as hot top material,the optimum hot top height was 50 mm,and the shrinkage cavity volume in Gd ingot was the smallest,which was 9.1 cm^(3).In conclusion,the hot top structure has a significant influence on the solidification process of high purity rare earth Gd casting targets,delaying the solidification of the upper melt in the mold,thus enhancing the liquid phase feeding ability,making the casting defect position rise and the volume decrease.The thermal insulation effect of different hot top materials is different.Compared with magnesium oxide,mullite hot top has a stronger thermal insulation effect.

关 键 词：高纯稀土 钆 铸造缺陷 热顶设计 数值模拟 

分 类 号：TG249.5[机械工程—精密仪器及机械]