搅拌摩擦焊制备泡沫铝发泡规律研究

Research on Foaming of Aluminum Foam by Friction Stir Welding

采用搅拌摩擦焊(FSW)工艺制备了粉末混合均匀、无缺陷的泡沫铝(AF)预制坯。对获取的高质量预制坯的发泡过程进行研究,探究最佳发泡温度和发泡时间,制备出孔径结构均匀、高孔隙率的铝合金泡沫夹芯板。运用FLUENT中VOF模型,对气泡在熔融铝液中的行为进行了模拟仿真,研究了泡孔在铝基体中的形成、生长、稳定和聚结过程。结果表明,当发泡温度为700℃、发泡时间为110 s时,孔隙率最高,为55.87%。由数值模拟可得,气泡在熔融铝中上浮的过程中伴随着变形,由圆形逐步变成扁平月牙状。在气泡运动过程中,气泡会与周围气泡发生聚合,变成大气泡。

The preforms of aluminum foam(AF)that foaming power was mixed evenly without defects were prepared by friction stir welding(FSW).The foaming process of the high-quality preform was studied,and the optimum foaming temperature and foaming time were explored.The aluminum foam with uniform pore size and high porosity were successfully prepared.VOF model in fluent was used to simulate the behavior of bubbles in molten aluminum,and the formation,growth,stability and coalescence process of bubbles in aluminum matrix were studied.The results show that when the foaming temperature is 700℃ and the foaming time is 110 s,the porosity is highest,55.87%.The numerical simulation shows that the bubble floats up in molten aluminum with deformation,and gradually changes from round to flat crescent.During the bubble movement,bubbles aggregate with the surrounding bubbles and become big bubbles.