The Processing and Properties of Syntactic Al Foams Containing Low Cost Expanded Glass Particles

• Published in: Advanced engineering materials Vol. 19; no. 11
• Main Authors: Wright, Andrew, Kennedy, Andrew
• Format: Journal Article
• Language: English
• Published: 01.11.2017
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.201600467

Expanded glass particles (EGP) are used to manufacture Al syntactic foams using a simple vacuum casting method. Clamping of the casting in the stainless steel mold is observed when preheating the mold to >400 C, causing damage to the EGP, resulting in a weaker foam but with the significant advantage of eliminating the yield drop, improving the energy absorption characteristics. The same effect in castings that are not clamped (for mold preheats <400 °C) can be achieved by quenching in liquid nitrogen. These “low strength” syntactic metal foams are a cost‐effective alternative to metal foams and porous metals (in terms of specific strength, stiffness, and energy absorption) rather than “conventional” syntactic foams which contain smaller, stronger, hollow microspheres. Foamed glass spheres can be used to make Al syntactic foams with low densities via a simple casting method. Paradoxically, enhanced energy absorption is achieved when the spheres are extensively damaged during processing or via an additional quenching step. These “low strength” foams are a cost‐effective alternative to metal foams and porous metals rather than “traditional” syntactic foams.