High temperature, long duration plasma torch test of a UHTC nose cone demonstrator

An ultra-high temperature ZrB2-SiC ceramic nose-cone was manufactured and tested in a plasma torch facility for 10 minutes at temperatures above 2300K. The nose-cone model was obtained from an hot-pressed billet via Electrical Discharge Machining. Resistance to oxidation and microstructure modifications subsequent to the expoure to the hot flux were evaluated on crosssections of the relevant portion of the model by using SEM-EDS and XRD analysis. Fluid dynamic numerical calculations were carried out to explain and correlate the experimental results. Spectral directional emissivity measurements were performed on the fly during the test by means of thermography coupled with dual-colour pyrometry, and the results were compared with previous laboratory measurements. The post-test cross-sectioning of the model after exposure showed a promising potential to withstand severe re-entry conditions with temperature exceeding 2300K, thanks to the formation of a steady-state external multiphase oxide scale. The numerical calculations, which simulated the chemical non-equilibrium flow around the model assuming a low catalytic surface behaviour (consistent with the previously measured catalytic properties of the constituent material), are in good accordance with the experimental results.