Completed funded project

The efficiency of thermal processes increases with the available temperature interval. The temperature range of the metallic superalloys used today is limited by their maximum operating temperature. In order for ceramics to be used in thermomechanically highly stressed areas, such as in gas turbines, the naturally brittle ceramics must be reinforced with ceramic fibres resistant to high temperatures. The fibres are embedded in a ceramic matrix. If fibres and matrix consist of oxide ceramics, this is called O-CMC (Oxide Ceramic Matrix Composites). Until now, O-CMCs have had an open-pored matrix. Their maximum application temperature is limited to approx. 1100 °C.

The aim of the project is to develop an O-CMC that can be used at significantly higher temperatures up to approx. 1250 °C. In addition, a demonstrator component made of this novel material is to be developed: a stator for micro gas turbines. The open-pored matrix of the O-CMC is to be replaced by a dense oxide ceramic matrix. In addition, fibre coatings are to be developed to bond the fibres to the matrix. It is to be shown that the efficiency of micro gas turbines can be significantly increased with the new material.

• Development of a multilayer fiber coating with YDS (yttrium disilicate), YMS (yttrium monolilicate), AlP (aluminum phosphate), alumina and carbon for ductile bonding of matrix fiber in an oxide dense CMC
• Coating of roving and fabric
• Development of a dense oxide ceramic matrix with process temperatures < 1250 °C.
  • Sealing of the matrix via infiltration with SiOC-forming resins or with crystalline glasses as glass melts
• Surface sealing of O-CMC components by means of glass-ceramic coatings
• Production of prototype components - stator - for a micro gas turbine made of silica fabric with low sintering Al₂O₃-SiO₂ matrix and sealing by means of glaze