AlSi12合金泡沫的真空发泡制备工艺研究

On the Vacuum Foaming Fabricating Processing of AlSi12 Alloy Foam

摘要:

为克服现有熔体发泡制备泡沫铝工艺中发泡剂含量高所带来的成本高、分散性差、与发泡工艺匹配难、降低材料性能等负面影响，本文采用新型真空发泡法制备AlSi12合金泡沫，并对其中的初始气孔及真空发泡AlSi12合金泡沫孔结构的形成及控制工艺进行了研究，结果表明：（1）AlSi12合金在620℃熔化保温1h、添加1%SiC和2?以2000r/min的速度搅拌10min增粘、添加微量（0.02%wt）TiH2以2000r/min的速度搅拌6min的条件下可获得均匀细小的初始气孔；（2）在真空度为5Pa下发泡10s，真空下冷却6min的条件下，获得了平均孔径2.4mm，孔隙率83.7%，孔结构均匀的AlSi12合金泡沫；（3）初始气孔以SiC、Al2O3、SiO2等第二相为气泡非均质形核的核心。

Abstract:

To overcome these shortcomings of the blowing agent, which is used too much as the foaming agent for fabricating aluminum foams in melt foaming processing, as high cost, poor dispersion, difficult to match the foaming process and degrade the performance of the material, a new vacuum foaming processing was employed to prepare AlSi12 alloy foams. The processes that related to the initial pores and the cell structure of the vacuum foamed AlSi12 foams were studied. The results showed that: (1) Well-distribution, fine initial pores were obtained by the processing parameters: melting AlSi12 alloy at 620℃ for 1h, adding 1%SiC and 2% Ca into the melt and stirring the melt for 10min with stirring speed 2000r/mm to increasing the melt viscosity, then adding a few of TiH2 (0.02%) into the melt and stirring the melt for 6min with stirring speed 2000r/min; (2) AlSi12 alloy foams with uniform cell structure, average pore diameter 2.4mm and porosity 83.7% were obtained by the vacuum foaming processing: foaming the melt for 10s with vacuum degree of 5Pa, and cooling the melt foams for 6min in vacuum surroundings; (3) The bobble nucleation of the initial pores in the AlSi12 alloy melt were heterogeneous nucleation, and these phases, SiC, Al2O3, SiO2, etc., acted as the nuclei of the heterogeneous nucleation.