泡沫铝夹芯板粉末冶金发泡机理的SR-CT研究

利用同步辐射装置的SR-CT,通过图像的断层扫描及3D重建,对轧制复合-粉末冶金发泡工艺制备的泡沫铝夹芯板(AFS)进行了泡孔结构演化的研究,分析了发泡过程中孔隙率的变化及大尺寸连通孔的形成原因。研究结果表明:具有微米级空间分辨率的SR-CT可清晰地观测到泡孔萌生及生长各阶段的泡沫结构。泡孔在发泡15~30 s阶段生成,形状为垂直于轧制方向的类裂纹孔。发泡45 s时,泡孔开始发生明显合并,继续延长发泡时间易导致形成大尺寸连通孔。芯层泡沫铝的孔隙率在泡孔的萌生阶段及合并阶段增长幅度较大,减少混料时发泡剂的"团聚"及提高芯层粉末致密度可获得良好的芯层泡沫结构。

Study on Powder Metallurgical Foaming Mechanism of Aluminum Foam Sandwich Using SR-CT

The research of cellular structure evolution of aluminum foam sandwich that made by the pack rolling/powder metallurgy foaming process has been done using SR-CT, and also the variation of porosity of aluminum foam and occurring of oversize connected pores have been analyzed. The results show that the cellular structure can be observed clearly during the appearing and growing stages by using SR-CT with the spatial resolution of micrometer. The bubble hole that similar to spalttupfel which is perpendicular to the rolling direction generated from 15 to 30 seconds, and then it is an obvious merge at about 45 seconds. With time going on, the large size connected hole form more easily. The porosity of aluminum foam grow quickly at the stage of appearing and merging process. So in order to gain excellent foaming structure of sandwich layer, the reduction of the reunion of foaming agent during mixing material and improvement of powder density of the sandwich layer is necessary.