Oral Poster Presentation
Manufacturing and comparison of AlSi12 matrix unimodal and bimodal syntactic metal foamsWednesday (07.10.2020) 18:49 - 18:52
Metallic foams (MFs) are increasingly used in the automotive industry due to their relatively low weight and high specific energy absorbing capacity. MFs are materials that contain a certain amount of porosity in the base metallic material. In special MFs, called syntactic foams, the second, porosity ensuring phase is usually formed with hollow spheres or closed-wall porous materials responsible for gas intake.
During our research, metal matrix syntactic foam (MMSF) samples were produced using two grades of ceramic hollow spheres (CHSs) of different diameters as filler material. The CHSs are made of high-purity alumina ceramic with nominal diameters of Ød1=7 mm and Ød2=2.4 mm. Three types of samples were compared: MMSFs with unmixed small, large and mixed CHSs in 1:1 ratio (uniformly distributed). AlSi12 alloy was infiltrated amongst the CHSs with low-pressure infiltration to form the desired cellular material. Manufacturing parameters have a significant influence on the quality of the samples. Different preheating and melt temperatures, infiltration pressures and time was applied to reach proper infiltration. The samples were evaluated and compared based on the standardized upsetting tests. The compressive strength, plateau stress and energy-absorbing capacity values were the main comparison factors of the specimens.
The importance of this research is to develop high-performance bimodal MMSFs which have higher specific mechanical properties than conventional MFs. This helps to achieve additional weight reduction, primarily as machine bumper parts or automotive components.