Abstract
Metal matrix syntactic foams (MMSFs) are becoming increasingly relevant from the lightweight structural materials point of view. They are also used as energy absorbers and as core materials for sandwich structures. The mechanical properties of MMSFs are extensively influenced by the properties of their filler materials which are used to create and ensure the porosity inside the metal matrix. As the properties of fillers are of such importance in the case of MMSFs, in this paper three different filler materials: (i) ceramic hollow spheres (CHSs), (ii) metallic hollow spheres (MHSs) and (iii) lightweight expanded clay particles (LECAPs), have been investigated in numerous aspects. The investigations cover the microstructural features of the fillers and the basic mechanical properties of the fillers and the produced MMSFs as well. The microstructure was studied by optical and electron microscopy extended by energy-dispersive X-ray spectrometry, while the basic mechanical properties were mapped by standardized compression tests. It was found that in the terms of cost-awareness the LECAPs are the best fillers, because they are ~100 times cheaper than the CHSs or MHSs, but their mechanical properties can be compared to the aforementioned, relatively expensive filler materials and still exceed the properties of the most ‘conventional’ metallic foams.
Highlights
The field of lightweight materials has become one of the most investigated areas today
The aim of this paper is to provide a connection between the features of the filler particles through their applicability as fillers in Metal matrix syntactic foams (MMSFs) to the mechanical properties of the produced MMSFs
Three types of filler materials have been investigated with different methods, these are: ceramic hollow spheres (CHSs), metallic hollow spheres (MHSs) and lightweight expanded clay particles (LECAPs)
Summary
The field of lightweight materials has become one of the most investigated areas today. One of the best way to increase the efficiency of a structure or machine is to reduce its weight. It can be done by using stronger materials which allow to design thinner structures, or by reducing the density while maintaining the strength of the material at a high level. If the choice is to reduce the density, closed-cell metallic foam is one of the best options. They are commonly made by injecting a gas or mixing a foaming agent into molten metal [1,2]. The main application fields are energy absorbers or sandwich panels and filled sections for structural applications [3,4]
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