Current trends in CMC research & development across DLR’s technology programs

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CMC Materials for Aircraft Brakes

Übersucht zur Herstellung von C/C-SiC und dessen Werkstoffeigenschaften. Entwicklung von Reibbelägen für Airbus A 400M. Neue Preformtechniken und Sandwichsrukturen für Bremsscheiben

Combination of PIP and LSI processes for SiC/SiC ceramic matrix composites

Silicon carbide fiber-reinforced silicon carbide matrix composites (SiC/SiC CMCs) are promising candidates for hot gas components in jet engines. Three common manufacturing routes are chemical vapor infiltration, reactive melt infiltration (RMI) and polymer infiltration and pyrolysis (PIP). A combination of the processes seems attractive: the remaining porosity after PIP process can be closed by subsequent siliconization, resulting in a dense material. This work describes a new approach of a combined PIP and RMI process. SiC/SiC CMCs were manufactured by PIP process using Hi-Nicalon Type S fibers. An additional RMI was carried out after a reduced number of PIP cycles. Microstructure was examined via microCT, SEM and EDS. Bending strength was determined to 433 ​MPa; strain to failure was 0.60%. The overall processing time was reduced by 55% compared to standard PIP route. The hybrid material contained 70% less unreacted carbon than material produced by LSI process alone

Three-dimensional preforming via wet-laid nonwoven technology for ceramic matrix composites

In this study, a new 3D preforming method was developed using wet-laid nonwoven technology, for application in manufacturing ceramic matrix composites (CMC). For this purpose, a process setup was developed and tested on an example geometry (radome). HTS 45 carbon fibers and Nextel610 alumina fibers were used for the preforming. The resulting C/C-SiC and OXIPOL materials were mechanically characterized and the microstructure was investigated. A radome was manufactured from each material and subjected to DLR's L2K and VMK wind tunnels. The tests have been successful with the C/C-SiC and OXIPOL radome. Overall the application-oriented tests show that load-bearing components can be produced with the newly developed preform method and that they also prove themselves in the application. The knowledge gained, demonstrates the potential of the 3D wet-laid nonwoven preforming method and represents a new possibility for CMC production with complex shapes

CMC-TurbAn: Optimisation of CVI fibre coating thickness in melt-infiltrated SiC/SiC CMCs & Development of environmental barrier coatings (EBC) for turbine applications

Vorstellung von Ergebnissen aus dem LuFo Projekt CMC_TurbA