Additively Manufactured Titanium Alloy Sandwich Structures for Thermal Protection

Abstract

Additively manufactured titanium alloy sandwich structures with lattice core have a potential use for thermal protection systems. To investigate the influence of the lattice core structure, four samples were manufactured in Ti-6Al-4V using electron beam melting. Two sample thicknesses and two lattice densities were realised. Plasma wind tunnel testing in the arc-heated facility L2K at the German Aerospace Center (DLR) was carried out to characterise their performance. Each sample was subjected to hypersonic air flow during four heating steps with an exposure time of 180 s each. Nominal cold-wall heat fluxes of 100 kW/m², 200 kW/m² and 500 kW/m² were achieved. All samples survived the test procedure. The formation of a liquid film was observed during the exposure to highest heat flux level. Within the investigated parameter space, the lattice core structure had negligible influence on the front temperature but affected the back temperature considerably. For the lowest heat flux condition, the thick sample with the light lattice showed the lowest maximum back temperature of 390°C . The sample thickness showed a higher effect on the maximum back temperature whereas the lattice density had the greater effect on the insulation-to-density performance.