Zirconium carbide (ZrC) is a promising ultra-high-temperature ceramic (UHTC) for thermal protection systems (TPS) due to its high melting point, thermal stability, and mechanical strength. However, its susceptibility to oxidative degradation and limited thermal shock resistance poses challenges for aerospace applications. This thesis investigates how prior oxidation history (defined by exposure temperature and duration) influences the thermal shock response of the zirconia oxide scale on monolithic ZrC. Samples were oxidized at 600°C, 700°C, and 800°C for varying durations, followed by thermal shock via water quenching. Post-exposure analysis using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and mass change measurements showed that increasing oxidation severity leads to thicker, brittle oxide scales with higher monoclinic ZrO2 content and elevated crack densities. A transition to failure-prone behavior occurs between 700°C and 800°C, with failure thresholds defined by a ≥10% surface crack density and monoclinic ZrO2 content exceeding 10%. These results establish oxidation-dependent limits for ZrC’s thermal shock resistance.

In this report, the preliminary design and sizing of a long-duration stationary Venus lander named KYTHERA is performed. In contrast with previous Venus landers, KYTHERA is designed to survive on the hellish Venusian surface for at least 200 Earth days to study long-term atmospheric and seismic phenomena. In addition to the chemical analysis of the atmosphere and seismic measurements, the lander is capable to do 20 individual chemical analyses of surface rock material, using Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy. To meet the duration goal, the lander is actively cooled, using a Stirling-generator-cooler chain to remove heat from the inside, powered by the radioactive decay of plutonium. The corrosion and heat resistant structure is sized to survive 120 Earth G-s of acceleration during entry and a landing impact speed of 8.5 m/s, as well as 93 bars of pressure difference at 460 °C. To maximize insulation efficiency, the internal structure of the lander (the coldbox) is separated from the outer shell (the hotbox) by 3.5 cm of vacuum. Although the mission is expected to fit within the required mass budget, the cost is likely to be exceeded, as the power system is more expensive than initially anticipated. The lander weighs 350 kg and is expected to cost around 300 million euros.