An innovative all-oxide fiber-reinforced ceramic matrix composite for high-temperature applications. A primary goal of DLR is the development of environmentally and economically favorable gas turbine engines with stable lean-combustion. The burning chambers of these turbines will be designed with new highly damage-tolerant and corrosion-resistant high-temperature ceramic matrix composites.
Fabrication of WHIPOX™
WHIPOX-components are fabricated using two computer-controlled winding facilities which were developed and assembled at the Institute of Materials Research. Winding bodies with an inner diameter of 500 mm and a width of 800 mm can be obtained. The winding pattern can be varied in a broad range. The typical wall-thickness of components ranges from less than 0.5 up to more than 5 mm. The organic protective coating of as received fibres is thermally removed. After this the fibre roving is infiltrated with a water-based slurry of the matrix precursor powders. The infiltrated fibre roving is pre-dried and wound-up on the winding mandrel. After the winding-process the wound bodies are dried or cut-up and removed form the mandrel. These flexible tapes can be either stored or used immediately for laminating or shaping in the wet state. The final WHIPOX products are obtained after drying, firing and machining.
Properties of WHIPOX™
WHIPOX exhibits high mechanical strength along with low specific weight. Due to the high porosity WHIPOX exhibits an outstanding, non-brittle fracture behavior. WHIPOX is stable against thermal load, oxidation and corrosive media. WHIPOX exhibits an excellent damage tolerance especially under extreme thermal shock or punctual mechanical overload (impact). The typical permeability of WHIPOX can be varied in a broad range by the application of ceramic coatings.
Further Applications of WHIPOX™
Due to its low heat capacity and the highly variable permeability WHIPOX components are also developed for applications in the field of combustion technology. Due to their high thermal shock resistance WHIPOX components are suitable as durable firing-aids or ceramic hot-gas filter elements, especially in the case of very high heating-/cooling rates. The properties of WHIPOX can be controlled by variation of fibres, matrices, fibre-content and winding pattern and therefore can be adapted to specific technical applications.