泡沫铝三明治结构粉末冶金法制备工艺及泡孔结构优化

Preparation Technology of Aluminum Foam Sandwich Panels by Powder Metallurgy and Optimization of Cellular Structure

摘要:

粉末冶金法可实现泡沫铝三明治结构面板/芯层的冶金结合,并在制备近终型泡沫铝异型件上优势突出。基于国内研究现状,本文完善了粉末冶金法制备工艺,并优化了泡孔结构。研究发现,芯层采用AlMg4Si8铝合金成分组成,钢质面板经边缘焊接密封处理后,当芯层粉末松装密度为1.12 g/cm_³时,在1500 kN轧制压力、0.06 m/s轧制速度及55％轧制压下率下,对灌满芯层粉末的包覆面板进行450 °C热轧,获得了面板/芯层冶金结合、致密度高的发泡前驱体。另外,当发泡剂TiH₂被低熔点Sn包覆预处理后,在发泡初期分解出的H₂被液态Sn包裹,避免了在固态基体空隙间的扩散,减少了裂纹的产生,发泡前驱体在720 °C发泡300 s后可获得泡孔结构相对均匀、72.7%孔隙率的泡沫铝三明治结构。

Abstract:

The metallurgical bonding of panel and core layer of aluminum foam sandwich can be realized by the powder metallurgy method, and the advantages in the preparation of near net shape aluminum foam part are prominent. Basing on the present situation of domestic research, the preparation process of aluminum foam sandwich by powder metallurgy method was improved, and the cellular structure was optimized in this paper. The results show that the foamable precursor with higher densification degree and metallurgy combination of panel and core layer can be obtained by hot-rolling of the coating panel filled with the core layer, when the density of the core layer powder is 1.12 g/cm_³, and at a rolling pressure of 1500 kN, a rolling speed of 0.06 m/s and a rolling reduction rate of 55%. AlMg4Si8 aluminum alloy was selected as a core layer component, and the edge welding seal preprocessing of the steel panel was carried out. In addition, the H₂ decomposed at the initial stage of foaming is wrapped by the liquid Sn when the blowing agent TiH₂ was pretreated by coating of the low melting point Sn, so that the diffusion of H₂ between the voids in the solid matrix was avoided and the generation of cracks was reduced, finally, aluminum foam sandwich with uniform cellular structure and 72.7% porosity can be obtained by foaming of foamable precursor at 720 °C for 300 s.