基于不同氢化物发泡剂的泡沫铝孔径分析及压缩性能

Pore size analysis and compressive properties of aluminum foams based on different hydride blowing agents

采用熔体发泡法制备泡沫铝,研究了氢化物系发泡剂的热分解行为与发泡效果的关联性,比较分析了泡沫铝静态压缩的实验力学行为及变形机制,考察了相对密度对闭孔泡沫铝材料的能量吸收能力和效率等性能参数的影响.结果表明:发泡剂的释氢行为会影响泡沫铝的发泡效果,在合适的分解温度下ZrH2可制备出孔径相对均匀、小孔率(孔径<1.5 mm)为80%的泡沫铝,而TiH2制备的泡沫铝孔径偏大,大孔率超过30%;利用SEM,EDS和XRD等检测方法发现孔壁及孔棱有氧化物和金属间化合物形成,可为气泡的稳定提供核心作用;ZrH2制备的泡沫铝屈服强度、弹性模量和能量吸收能力均小于TiH2制备的泡沫铝,但二者能量吸收效率较相似;而ZrH2制备的泡沫铝具有较长的屈服平台区,相对密度对泡沫铝压缩性能影响显著,当相对密度增加32%,吸能量增加81%,且相对密度与屈服强度的关系可取φ=0.6进行理论估算.

Aluminum foam was prepared by melt foaming method.The relationship between thermal decomposition behavior and foaming effect of foaming agent was studied.Besides,the static compressive experimental mechanical behavior and deformation mechanism of foamed aluminum were compared and analyzed.Further more,the effects of relative density on the performance parameters such as energy absorption capacity and efficiency of closed-cell aluminum foam were investigated.The results show that the foaming effect is affected by behavior of foaming agent.ZrH2 can produce aluminum foams with relatively uniform pore size and 80%small porosity(<1.5 mm)due to the matching decomposition temperature,while TiH2 can produce aluminum foams with larger pore size of more than 30%.It is found by SEM,EDS and XRD that the formation of oxides and intermetallic compounds on the pore walls and edges can provide a key role for bubble stabilization.The static compression experiments show that the yield strength,elastic modulus and energy absorption capacity of aluminum foams prepared by ZrH2 are smaller than those of aluminum foams prepared by TiH2,and the energy absorption efficiency of aluminum foams is similar,but have a longer yield plateau region.It has been found that the relative density has a significant effect on the compressive properties of aluminum foams.When the relative density increases by 32%,the energy absorption capacity increases by 81%,and the relationship between relative density and yield strength can be calculated theoretically withφ=0.6.