Novel thruster reactor made by Selective Laser Melting in metal lattice structures for the catalytic decomposition of H2O2

In the single propellant thruster an important push is coming for the use of non-toxic and rialable materials, as hydrogen peroxide. The exothermic decomposition of hydrogen peroxide with production of water and oxygen gives the necessary thrust to the device; rapid decomposition is promoted by the presence of a catalyst, such as manganese dioxide, inside a reactor. In the state of the art this reactor consists of several parts mounted together through flanges and it contains the catalyst chips through which hydrogen peroxide passes and reacts. This is a heavy structure due to the joints between the parts and the reactor presents a low efficiency; in the aerospace field it is essential to produce very light, reliable and increasingly efficient devices. For this purpose the reactor for the catalytic decomposition of H2O2 was re-designed to be produced in one piece and with the support for the catalyst integrated into the structure inside: this allows to remove the joints between the parts, reducing weight and improving the reliability. The support for catalyst is made of a trabecular structure with high specific surface area, regular and controllable porosity, and on wich it is possible to deposit the appropriate catalyst by electrodeposition or immersion. A product of this complexity can only be produced through Additive Manufacturing technology, such as Selective Laser Melting (SLM). SLM allows to produce complex shapes, as lattice geometries, without additional costs and permits to realize components with high buy to fly ratio. In order to make possible the innovative design proposed, a wide range of experimental tests was conducted: different trabecular structures were studied with two types of materials used for SLM, AlSi10Mg and Ti6Al4V. Specimens were produced following a Design of Experiment to evaluate the effects of the factors: the factors are five cell types, three different solid volume fractions and three different cell sizes. All the specimens were subjected to compression tests. The results were analyzed through the stress-strain curves, while all the evaluations and comparisons on the fracture mechanisms were performed through the optical microscope and the analysis of the high resolution video of the tests. The complete geometry of the reactor with the different cell shapes and the different dimensions was evaluated through CFD simulations with Siemens high fidelity CFD code. Moreover, process efficiency and conversion analysis within the reactor were evaluated with Aspen Plus.