Different methods to synthesize ceramic foams

Abstract

Ceramic foams are cellular structures composed of a three-dimensional network of struts. These highly porous materials have a lot of applications as filters for molten metal, hot gas and diesel engine exhausts filters, catalyst carriers, biomaterials, thermal insulators for furnaces and aerospace applications, gas combustion burners and lightweight building materials. As the application domains for these materials vary widely, the ultimate properties of the foam posed by the specific use are also diverse. As a consequence, different routes for the production of these foams have been developed, each with their own window of properties. In this contribution we focus on three manufacturing techniques: (1) reaction bonded modified polyurethane technique, (2) gel casting and (3) a hollow beads method. The flow sheets of these manufacturing routes are explained with the main accent on the shaping aspect of the method. The advantages and disadvantages of these methods are described on the hand of their structure, characterized by field emission scanning electron microscopy (FESEM), computer-assisted microtomography (μCT), image analysis (IA) and mechanical tests. Finally, some examples of ceramic foam projects are presented as the recycling of Al, the trapping of the particles of diesel engines, and the synthesis of scaffolds for bone substitutes.