粉末冶金泡沫铝合金的制备、表征与性能研究

发布时间：2018-08-12 20:11

【摘要】：本文采用成分为AlSi11的预合金化粉、铝硅元素混合粉,成分为AlSi7-4vol%SiC的AlSi11预合金化粉、铝元素粉和SiC粉的混合粉,成分为AlSi7Cu4的铝硅铜元素混合粉四种不同的基体粉末,以TiH2为发泡剂,运用混粉-冷等静压-真空除气-热挤压的工艺制备了致密泡沫铝前驱体。对前驱体加热发泡,获得不同发泡时间的系列泡沫铝样品。通过对不同发泡时间泡沫铝孔结构的分析,研究了前驱体结构对气孔结构演化和泡沫铝孔壁稳定性的影响。实验结果表明:本文所采用的工艺制备出泡沫铝前驱体具有良好的可发泡性,且不同前驱体制备的泡沫铝在孔隙率和孔结构方面有所差异。AlSi11预合金粉前驱体制备的泡沫铝孔隙率最高72%,平均孔径为1.18 mm~3.38 mm,孔径分布很不均匀;AlSi11元素混合粉前驱体制备的泡沫铝,最大孔隙率为85%,平均孔径为1.38mm~1.99 mm,孔径分布较为均匀;AlSi7(AlSi11合金粉与铝元素粉混合)-4vol%SiC前驱体制备的泡沫铝,孔隙率81.6%,平均孔径为0.87 mm~1.23 mm,孔径分布最为均匀;AlSi7Cu4元素混合粉前驱体制备的泡沫铝,样品孔隙最高83.2%,平均孔径1.11 mm~1.32 mm,孔径分布较为均匀。经过分析研究可知,泡沫铝的孔隙率和孔结构的差异,主要是由前驱体组织结构不同引起的。前驱体中陶瓷颗粒与铝基体的结合状态决定了前驱体发泡前期的气孔形核数量和气孔扩展模式;发泡过程中前驱体中的固相成分(包括氧化夹杂物和未熔化的基体颗粒)会对泡沫铝孔结构稳定性产生巨大的影响。对各个前驱体发泡所得泡沫铝进行压缩实验,通过不同角度对比,研究了泡沫铝孔隙率、孔结构以及前驱体成分对其压缩性能和吸能特性的影响。研究结果表明:泡沫铝的压缩性能和吸能特性受孔隙率、孔结构、前驱体成分等多方面因素影响。孔隙率增大,泡沫铝的压缩性能和吸能特性变差;孔径较小且均匀的泡沫铝,力学性能更加优秀。四组样品中,成分为AlSi7-4vol%SiC的前驱体制备的泡沫铝在压缩性能和吸能特性方面,表现要优于其它三组样品。
[Abstract]:In this paper, four kinds of matrix powders, which are pre-alloyed powder of AlSi11, mixed powder of Al-Si element, AlSi11 prealloyed powder of AlSi7-4vol%SiC, mixed powder of aluminum element powder and SiC powder, and aluminum-silicon-copper element mixed powder of AlSi7Cu4, are used. TiH2 is used as foaming agent. A dense aluminum foam precursor was prepared by mixing powder, cold isostatic pressure, vacuum degassing and hot extrusion. A series of aluminum foam samples with different foaming time were obtained by foaming the precursor. The influence of precursor structure on the evolution of pore structure and the stability of aluminum foam wall was studied by analyzing the pore structure of aluminum foam at different foaming times. The experimental results show that the foamed aluminum precursor prepared in this paper has good foaming property. The porosity and pore structure of aluminum foams prepared by different precursors are different. The porosity of aluminum foams prepared by the precursor of AlSi11 prealloyed powder is the highest, the average pore size is 1.18 mm~3.38 / mm, and the pore size distribution is very uneven. Aluminum foam, The maximum porosity is 85, the average pore size is 1.38mm~1.99 mm, and the pore size distribution is more uniform. AlSi7 (AlSi11 alloy powder mixed with aluminum element powder) -4volSiC precursor is used to prepare foamed aluminum. The porosity is 81.6, the average pore size is 0.87 mm~1.23 / mm, and the pore size distribution is the most uniform. The pore size of the sample is 83.2 mm and the average pore size is 1.11 mm~1.32 / mm, and the pore size distribution is more uniform. The results show that the difference of porosity and pore structure of aluminum foams is mainly caused by the different structure of precursor. The combination state of ceramic particles and aluminum matrix in the precursor determines the number of pore nucleation and the pore expansion mode in the early foaming stage of the precursor. During the foaming process, the solid composition of the precursor (including oxidized inclusions and unmelted matrix particles) has a great influence on the pore structure stability of aluminum foams. The effects of porosity, pore structure and precursor composition on the compressive properties and energy absorption of foamed aluminum foams were studied by comparison of different angles. The results show that the compressive and energy absorption properties of aluminum foams are affected by many factors such as porosity, pore structure and precursor composition. With the increase of porosity, the compressive and energy absorption properties of aluminum foam become worse, and the mechanical properties of aluminum foam with small and uniform pore size are better. In the four groups of samples, the performance of foamed aluminum prepared by precursor containing AlSi7-4vol%SiC is superior to that of the other three groups in terms of compression performance and energy absorption characteristics.
【学位授予单位】：北京有色金属研究总院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TF125;TB383.4

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