Nature inspired novel processing routes for ceramic foams

A closer look at some natural materials from animal and plant sources and the phenomenon driving their use in day to day applications resulted in investigation of their potential in processing of ceramic foams. Ceramic foams were made using aqueous ceramic slurries based on chicken egg white, soap nut fruit extract and sucrose. Egg white and soap nut extract were utilised for their natural foaming ability and binding of ceramic particles. Ceramic foams were produced by foaming the aqueous ceramic slurries by mechanical agitation followed by casting. The egg white based foams were set by coagulation achieved through sprinkling of acid, however use of acid was not successful with foams made from slurries with low and high ceramic loadings. Sucrose was utilised for its moisture retention ability and it not only simplified the egg white based process but also helped to achieve foams with exceptional characteristics including porosity exceeding 95%. Sucrose containing egg white based ceramic foams could be set by heating soon after casting. The soap nut based foams were processed in a similar way and were set simply by drying. Soap nut based foams exhibited a much higher number of interconnections per cell. Foams with a range of porosity and microstructural features could be produced from egg white and soap nut based slurries by using different combinations of ceramic loading and binder content in the premix or by varying the foaming time and slurry to container volume ratio.