Effect of cubic boron nitride addition on the properties of aluminium composite foams

Although there are several researches focused on the improvement of strength of metal based foams by adding ceramic particles, the investigations of the effect of cubic boron nitride (cBN) reinforcement on the mechanism or properties of Al foams are very limited so far. In this study, it is aimed to develop and investigate the properties of Al matrix by cBN addition in different amounts (2, 5, 10 wt%). cBN/pure Al composite foams were fabricated by using boric acid (H3BO3) as foaming agent with the mean size of 500 μm under compacting pressure of 150 bar and sintering temperature 620 °C for 3 h at Ar atmosphere. The theoretical densities of sintered composite foams with porosity fraction of 50 vol% were measured according to Archimedes method. The phase analyses were conducted employing an XRD. The microstructures were studied by stereomicroscope equipped with image analyser. Compression tests were performed at the strain rate of 10−3 s−1 for evaluating the compressive behaviour and energy absorption capacity. The effects of cBN on foaming mechanisms and the mechanical properties of foam composites were discussed in detail. cBN-added Al composites showed superior compressive properties in comparison to fabricated Al foams according to the literature.