【作者】 王永胜；

【导师】 左孝青；

【作者基本信息】 昆明理工大学 ， 材料学， 2009， 硕士

【摘要】 泡沫铝是复合材料,由金属相和气孔组成,可应用于多个领域,倍受人们关注。本文主要研究了小孔径泡沫铝的制备工艺、细化机理及力学性能。本文用熔体法制备出孔径为1.3mm、孔隙率为70.5%结构均匀的泡沫铝,并得到其工艺参数：铝液温度为685℃；加入的钙为1.5%、镁为0.5%、发泡剂为0.3%；钙、镁加入后的搅拌5min；处理发泡剂400℃/6h+500℃/1h；发泡剂分散60s；分散速度为3000rpm；保温发泡1.5min。对小孔径泡沫铝的制备机理进行了研究,研究表明：(1)气泡稳定性主要受到熔体粘度及其表面张力的影响,高粘度和低表面张力有利于气泡稳定性的提高；(2)高粘度与低速搅拌(1000rpm)均不利于发泡剂的分散,受发泡剂分解时间的影响,搅拌时间不宜过长(<70s),改变工艺条件,可降低发泡剂的团聚现象,有利于制备结构均匀的小孔径泡沫铝试样；(3)经过氧化预处理可推迟发泡剂TiH2的分解时间,降低其分解率。处理温度越高(450℃-520℃),分解时间的推迟越明显,发泡剂TiH2释放的氢气量降低(185ml-125ml)。经过合适的氧化预处理的发泡剂配合适当的搅拌发泡时间可以在保证气泡分布均匀的基础上获得较小的平均孔径；(4)金属熔体中的TiH2等固相颗粒均可成为气泡非均匀形核的核心。研究了小孔径泡沫铝静态压缩性能,结果表明：孔隙率在63.5%-76%范围的纯铝基小孔径泡沫铝,屈服强度在5.2MPa-14.8Mpa范围,能量吸收性能在5.2MJ/m3-11.5MJ/m3范围；当试验制的的泡沫铝平均孔径的减小时,其屈服强度和能量吸收能力提高。更多还原

【Abstract】 Aluminum foam is a composite material which is consisted metallic matrix and gas bubbles. It has an extensive application in many different areas. Tremendous research activities about aluminum foam have been implemented. Preparation and mechanics of pore diameter reducing and Compressive property was researched in this paper.Aluminum foam with fine cell structure was made successfully by melt foaming in this paper. The average cell diameter of aluminum foam is about 1.3 millimeter, The porosity is 70.5%. The cell structures are distributing uniformly. The optimal processing parameters is:melting temperature of aluminum 685℃; content of Calcium 1.5%; content of Magnesium 0.5%; stirring time 5min; content of foaming agent 0.3%; foaming agent being treated on 400℃6h and 500℃1h; foaming time 60s; stirring speed 3000rpm; time of heat insulation 1.5min.Preparation mechanism of Al foam with fine cell structure was researched in the paper. The result illustrated that:(1) Bubble stabilization has close relationship with melt viscosity and surface tension. When melt viscosity increased and surface tension decreased, bubble stabilization will be improved. (2) When melt viscosity increased and stirring speed slowed, dispersion of foaming agent will be lower. The stirring time could not very long(<70s), becouse of the available dispersion time of TiH2. The aggregation of foaming agent can be improved and aluminum foam with fine cell structure can be preparation by changing the condition of processing. (3) Oxidizing of foaming agent could delay the starting decomposition time and slow the decomposition rate. When the temperature of oxidizing of foaming agent increased from 450℃to 520℃, the effect of slower the decomposition rate will enhanced. However, the volume of decomposition foaming agent will reduced from 185ml to 125ml. When the temperature of oxidizing of foaming agent and stirring time matched, aluminum foam with fine cell structure will be maded. (4) Solid-phase particles in the aluminum melt could act as the nuclei during heterogeneous nucleation.Compressions of Al foam with fine cell structure was researched in the paper. Yield strength of aluminum foam (porosity between 63.5%-76%) is 5.2 MPa to 14.8 MPa and energy absorption capability is 5.2 MJ/m3 to 11.5 MJ/m3. Yield strength and energy absorption will be improved with cell diameter reducing.更多还原