Ultra High Temperature Ceramic Matrix Composites

Informazioni relative al progetto

ID dell’accordo di sovvenzione: BRPR950110

Progetto chiuso

Data di avvio 1 Gennaio 1996

Data di completamento 30 Giugno 1999

Finanziato da

• Specific research and technological development programme in the field of industrial and materials technologies, 1994-1998

Costo totale € 0,00

Contributo UE Nessun dato

Coordinato da

UNIVERSITY OF BIRMINGHAM
United Kingdom

Exploitable results

ULTRA HIGH TEMPERATURE CERAMIC MATRIX COMPOSITES

The aim of the programme was to develop a fundamental understanding of the factors controlling the high temperature strength of complex oxide materials and to apply those principles in the development of fibres, interphases and matrices for the fabrication of ultra high temperature CMCs. The UHTCMC programme has been successful in meeting these objectives as evidenced by the achievements presented below. Material Selection Creep behaviour of dense samples of new oxide materials has been tested in air up to14000C . A data base has been established of properties of oxides relevant to the development of oxide-based composites and models for describing the creep behaviour of oxide composites have been critically assessed. A specific quantitative model has been implemented using a simple computer software. Guidelines for the selection of oxides and their microstructures for use in high- temperature composites have been presented. The compatibility and chemical/micro structural stability of new complex oxide material couples has been investigated and a series of pseudo-binary A1203-YAG materials with creep resistant model structures investigated. Polycrystalline Oxide Fibres A pilot scale fibre spinning rig has been constructed enabling multiple small diameter ceramic fibres to be continuously drawn. Small diameter polycrystalline fibres have been prepared from a novel complex multi-component precursor. The raw materials are relatively inexpensive, the precursor sol is stable in air and can be readily extruded in the form of 100 filament tows and fibres are microstructurally stable to at least 1400 C. High room temperature tensile strengths have been recorded (comparable to commercially available oxide fibres) and creep tests indicate significantly higher creep resistance than the best commercial fibre (Nextel 720). Interphase Materials and Deposition Methods A series of potential interphase materials were studied in relation to synthesis/fibre deposition, reactivity with possible CMC fibres and matrices (Al2O3, mullite, YAG, spinel) and interface debond energy with compatible oxides.These complex oxides, with generic formula MXO4, were deposited on a number of different fibre substrates using solution coating and PVD methods. Fibre, interphase and matrix couples with suitable processing and compatibility characteristics were identified, coated fibres were embedded in a matrix and debond capability demonstrated. Composite Processing Techniques CMC processing technology focussed on the development of slurry infiltration techniques followed by pressureless sintering in order to achieve the objective of low cost CMC component manufacture. Several different approaches to slurry infiltration were investigated. A comprehensive slurry development programme was undertaken to maximise matrix density. An optimized single step infiltration process has been developed which simultaneously puts in place both the interphase and the matrix. CMCs fabricated using this process are demonstrating tensile strengths in the range 150-180 MPa with no loss in strength to 1150?C. Fabrication of complex shapes has been demonstrated by the manufacture of a hollow aerofoil component.