Sep 16

Structural effects on the high temperature performance of the Super High Temperature Additive Manufactured Resistojet (STAR)

Christopher Ogunlesi, Dr Angelo Grubisic, Dr Federico Romei and Matthew Robinson

36th International Electric Propulsion Conference: IEPC

15/09/19 → 20/09/19

Vienna, Austria


This study uses non-destructive techniques to investigate the surface roughness, porosity and overall build quality of tantalum, tungsten and 316L stainless steel versions of the Super High Temperature Additive Manufactured Resistojet (STAR). The analysis serves to validate manufacturing approaches for the additively manufactured components produced by Selective Laser Melting (SLM) by verifying the build quality of a complex geometry. X-ray Computed Tomography (XCT) was successfully utilised in order to produce three-dimensional (3D) surface meshes of the complex internal structures of the thrusters, which were then compared against the original design data generating a nominal (as designed) to actual (as manufactured) comparison. These scans showed that the majority of the heat exchangers deviated less than 150µm from the nominal. However, beam-hardening affects resulted in higher density areas of the thruster difficult to resolve. Optical interferometry showed that the roughness of the tantalum thruster was notably higher (18.03µm Ra average) than that of the 316L thruster (14.06µm Ra average). SEM analysis showed that this was most likely due to the significant amount of balling on the Tantalum surface. Optical microscopy showed that the 316L and tantalum thrusters were both achieved high densification levels (>99% and 98% respectively) however the distribution of pores were found to greatly differ between the two.