Recent Advances in the Analysis, Measurement, and Properties of Composite Metal Foams

Abstract

Composite metal foam (CMF) is a novel lightweight metal matrix composite material with lightweight, high strength to density ratio and high energy absorption capabilities. The material can be made out of many different metals, alloys, and combinations, e.g. aluminum, steel, titanium, etc. For example, it can be made 100% out of steel, but, due to its porosities, it will weigh as light as aluminum. CMF is made of closely packed metallic hollow spheres with a metallic matrix that fills the empty spaces in between spheres. In every combination of the spheres and matrix materials, the final product weight will be ~30–35% of the weight of the parent material; the rest would be the air trapped inside its porosities. In this study, a scaled-down version of the torch fire experiments specified in 49 Code of Federal Regulation (CFR) Part 179, Appendix B was developed to provide initial data on evaluating the thermal protection performance of steel-steel composite metal foam (S-S CMF) in the torch fire conditions. S-S CMF panels of 30 × 30 cm dimensions are manufactured and tested to evaluate their survivability when exposed to a 30-minute torch fire condition of high velocity jet fire with a gas temperature of 1204°C in accordance with 49 CFR Part 179. Testing was performed to characterize the jet burner gas temperature and velocity flow field, and a calibration fire test was conducted using steel only as required by the test specification. The assembly was tested in duplicate in two consecutive simulated torch fire exposures as specified in 49 CFR Part 179, Appendix B. Based on the experimental results, a 15 mm thick steel-steel composite metal foam tested as novel insulation system met the acceptance criteria for the simulated torch fire testing and is expected to pass when tested at a full size of 122 × 122 cm dimensions. The main factor for fire resistance and thermal protection performance of S-S CMF is attributed to the large air content in the material.