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Selective Material Characterisation of Ceramic Matrix Composites for Advanced Gas Turbines
Abstract
fossil combustibles;high temperature performance;ceramic matrix composite;gas turbines;rank materials
The development of aero-engine and aircraft industry is aimed to hypersonic technology, efficiency enhancements and pollutant emission reductions. This objective can only be reached by increasing the operating temperatures, utilising new materials which mechanical properties are retained up to high temperatures. SiC matrix composites reinforced with carbon fibres (C/SiC) are good examples with very good bending and thermal shock resistance at temperatures up to 1600ºC as well as low density. However, the fact which currently inhibits the application of these materials is the high oxidation rate of carbon fibres at temperatures above 450ºC. In the first part of the paper, a review of the most important properties and oxidation mechanisms of C and SiC has been carried out. The influence of each material disposition, individually and as composite, has been analysed.
El desarrollo de la industria aeroespacial se orienta actualmente hacia la tecnología hipersónica, el incremento en el rendimiento de las reacciones de combustión y la reducción de la emisión de contaminantes. Estos objetivos sólo pueden alcanzarse aumentando la temperatura de combustión, para lo cual es necesario desarrollar nuevos materiales que conserven sus propiedades mecánicas hasta temperaturas muy elevadas. Entre ellos se encuentran los materiales compuestos de matriz de SiC reforzada con fibra continua de carbono (C/SiC), cuyas propiedades más importantes son una elevada resistencia a flexión y al choque térmico desde temperatura ambiente hasta 1600ºCy su reducido peso específico. Sin embargo, el principal problema que acompaña a los materiales compuestos C/SiC es la elevada velocidad de oxidación de la fibra de carbono a partir de 450ºC. En la primera parte del trabajo se realiza una revisión de las características más relevantes del carbono y SiC, y de su comportamiento frente a la oxidación, tanto por separado como formando parte de materiales compuestos de matriz de SiC y fibra de C.
Lifetime predictions for carbon-fiber based ceramic matrix composite components working under transients and cyclic environmental and mechanical load was carried out in a straight-forward manner with the presented `real material' modelling strategy. This includes the prediction of lifetimes of entire components as well as the assessment of existing material systems and subsystems for material selection purposes, and the definition of improvement requirements for material development. Modelling provides also valuable contribution to the theoretical understanding of mass loss mechanisms during stationary and transient operation, and the assessment of the representativity of the chosen test conditions.
For future reentry vehicles ceramic matrix composites (CMC) are very favorable materials for hot structures and thermal protection systems. This paper describes the fabrication and evaluation of CMC-components manufactured by the liquid impregnation technique. This process offers the potential for a low-cost CMC production for all components which can be fabricated by resin transfer molding (RTM) or other techniques for reinforcing polymers. The two main fabrication steps, the component shaping and the matrix conversion to ceramics, are described in detail. Experimental data on infiltration parameters as well as mechanical properties and oxidation resistance of the produced fiber ceramics were determined. Emphasis was given on manufacturing real components like panels with integrated stringers to demonstrate the feasibility of the process.
Ceramic Matrix Composites For Advanced Power Generation, Advanced Materials and Mechanical Properties: Proceedings of ICAM 96
- F. Rosatelli
- C. Luzzatto
- K. Iffländer
- C. Mao