Dynamic Non-Equilibrium Thermal Gravimetric Analysis of Oxidation Rate Measurements for Ultra-High Temperature Ceramics up to 1600° C
Start Date
28-2-2012 10:20 AM
End Date
1-3-2012 12:30 PM
Description
During hypersonic flight, vehicles need materials such as ultra-high temperature ceramics (UHTCs) for thermal protection system in order to withstand temperatures greater than 2000°C; therefore, understanding the oxidation behavior of these materials is important. We examine oxidation behavior of ZrB2-SiC composites by investigating the ratio of total specimen edge length to total specimen surface area and determine its relevance for developing reliable oxidation methods. We also investigate dynamic non-equilibrium thermogravimetric analysis (DNE TGA), which differ from conventional oxidation rate measurements by not including mass changes from heating and cooling. This method of DNE TGA is used to oxidize UHTCs and carbon to obtain isothermal rate measurements from 1000-1600°C and 0.29-19 kPa pO2. We determine, for reliable data, specimen parts with ratios less than 0.5 should be used for oxidation testing due to the reduced effect of edge and corner oxidation compared to bulk oxidation for UHTCs. Isothermal in situ mass measurements follow similar trends with temperature for DNE TGA; with increasing temperature, overall mass gains increase for UHTCs. Pressure dependence of DNE TGA results in mass gain from 8.9-19 kPa pO2 and mass loss from 0.29-2.0 kPa pO2 for UHTCs.
Dynamic Non-Equilibrium Thermal Gravimetric Analysis of Oxidation Rate Measurements for Ultra-High Temperature Ceramics up to 1600° C
During hypersonic flight, vehicles need materials such as ultra-high temperature ceramics (UHTCs) for thermal protection system in order to withstand temperatures greater than 2000°C; therefore, understanding the oxidation behavior of these materials is important. We examine oxidation behavior of ZrB2-SiC composites by investigating the ratio of total specimen edge length to total specimen surface area and determine its relevance for developing reliable oxidation methods. We also investigate dynamic non-equilibrium thermogravimetric analysis (DNE TGA), which differ from conventional oxidation rate measurements by not including mass changes from heating and cooling. This method of DNE TGA is used to oxidize UHTCs and carbon to obtain isothermal rate measurements from 1000-1600°C and 0.29-19 kPa pO2. We determine, for reliable data, specimen parts with ratios less than 0.5 should be used for oxidation testing due to the reduced effect of edge and corner oxidation compared to bulk oxidation for UHTCs. Isothermal in situ mass measurements follow similar trends with temperature for DNE TGA; with increasing temperature, overall mass gains increase for UHTCs. Pressure dependence of DNE TGA results in mass gain from 8.9-19 kPa pO2 and mass loss from 0.29-2.0 kPa pO2 for UHTCs.