Evaluation of Ultra High Temperature Ceramics and Coating-Systems for their Application in Orbital and Air-Breathing Propulsion

摘要

Combustion chambers of orbital thrusters and components of dual-mode ramjets require materials which are able to withstand high aerodynamic and thermo-mechanical loads during typical operation. Higher combustion efficiency and/or performance lead to higher combustion temperatures and therefore higher material working temperatures in the range of 1600°C to 1900°C. In addition to that severe thermo-chemical interactions between the combustion products and the substrate (e.g. oxidation, carburetion, nitruration) complete this harsh environment. Such demanding requirements in combination with a high thrust to weight ration limit the field of possible material candidates to ultra-high-temperature ceramics, ceramic matrix composites (CMCs) (e.g. C/SiC, C/C-SiC...) and coating systems (e.g. P-SiC, HfC, ZrB_2, HfB_2...). Using the novel established EADS ERBURIG~K (Environmental Relevant Burner Rig-Kerosene) testing facility different CMCs with Ultra-High-Temperature Coatings (UHTCs) were investigated in the temperature range from 1300°C to 2050°C and under relevant operational conditions. Different C/SiC materials with different refractory based ceramic coatings were tested in the ERBURIG~K test-rig in kerosene/oxygen combustion environments in oxidizing and reducing atmospheres and at high gas velocities to assess its suitability for combustion chamber relevant environments. During these tests, different test set-ups and test conditions on flat sample specimens were investigated. Sample temperature, weight loss, coating recession and surface composition were analyzed. Finally tests with coated CMC micro combustion chambers and fuel injection struts of a ramjet heat exchanger will cover a possible geometrical influence.