DEVELOPMENT AND EVALUATION OF DENSITY AND PORSITY OF ALUMINIUM FOAMS

Abstract

The characteristic of metal foams is a very high porosity typically 75–95% of the volume consists of void spaces making these ultra light materials. The strength of foamed metal possesses a power law relationship to its density; i.e., a 20% dense material is more than twice as strong as a 10% dense material. Methods for producing metal foams are many, but obtaining repeatability in the properties is very difficult. The main challenge posed by the metal foam is that obtaining homogeneous porosity. Metal foams are a new kind of materials with low densities and novel physical, mechanical, thermal, and electrical properties. They can be divided into closed cell and open cell structures Although lot of problems involved in the development of metal foams, research people are attracted to the metal foams because of its attractive properties like acoustic damping, bomb mitigation, light weight etc. By considering the development of Aluminium foams as important aspect, some methods have been adopted and attempts have been made to produce metal foams at lower cost using a different foaming agent which are cheaper than the conventional foaming agent. The methods developed for the Aluminium foams were Aluminium foam production using NaCl crystal as a place holder in the Al melt, Aluminium foam production using NaCl crystal as a place holder in sand salt mould, Aluminium foam production using NaCl crystal as a place holder by simultaneous pouring i.e., fusion including both foaming agent and salt concept. The problems associated in each process and its effect on the density and porosity of the foam are discussed.