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Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Theses and Dissertations
Ultra high temperature ceramics (UHTCs) are leading candidates for aerospace structural applications in high temperature environments, including the leading edges of hypersonic aircraft and thermal protection systems for atmospheric re-entry vehicles. Before UHTCs can be used in such applications, their structural integrity and environmental durability must be assured, which requires a thorough understanding and characterization of their creep and oxidation behavior at relevant service temperatures.
Microstructures And Mechanical Behavior Of Nial-Strengthened Ferritic Alloys At Room And Elevated Temperatures, Zhiqian Sun
Microstructures And Mechanical Behavior Of Nial-Strengthened Ferritic Alloys At Room And Elevated Temperatures, Zhiqian Sun
Doctoral Dissertations
In order to improve the thermal efficiency and decrease the greenhouse gases emission, it is required to increase the steam temperature and pressure in fossil-energy power plants. In the United States, research has been performing in order to push steam temperature to 760 Celsius degree and steam pressure to 35 MPa. However, the highest operational temperature for current commercial heat-resistant ferritic steels is ~ 620 Celsius degree. In this sense, new advanced ferritic alloys with better creep resistance are needed, considering such service conditions in next-generation ultra-supercritical fossil-energy power plants.
Coherent B2-ordered NiAl-type precipitates have been employed to reinforce the …
Rheology Of Cross-Linked Polymers And Polymer Foams: Theory And Experimental Results, John Herman
Rheology Of Cross-Linked Polymers And Polymer Foams: Theory And Experimental Results, John Herman
Wayne State University Dissertations
Typical polymers have a time-dependent response to loading which results in stress relaxation or creep. Models using springs/dashpots or Volterra integrals are capable of predicting the material response, but place little or no emphasis on the reasoning behind the response. This research proposes a microscopic reasoning behind polymer chain movement, while developing a model to predict the creep and stress relaxation of a polymer foam. Based on the theorized slip/stick of polymer chains as they slide past each other, this model successfully predicts the behavior of a PMI polymer foam under tensile loads. This model lends insights into polymer microscopic …