High Temperature Materials: an Introduction to Onera’s Contribution


T. Khan

The third issue of Aerospace Lab is dedicated to high temperature materials.
Onera has been at the forefront of research and development for this
class of materials for the past five decades, especially for aerospace engine
applications. Starting in the mid 1960’s, many new materials and processes
were invented, and cutting-edge research was carried out during this period.
Similarly and concurrently, great progress has been made in mechanical

Potential and Perspectives for Oxide/Oxide Composites


M. Parlier, M.-H. Ritti, A. Jankowiak

The challenge for oxide/oxide composites is to provide an alternative to
SiC/SiC composites with the aim of decreasing the cost of manufacture
and improving the thermal stability in air at high temperature. Oxide/oxide
composites consist of a porous alumina matrix reinforced by fibers of the

Potential of Directionally Solidified Eutectic Ceramics for High Temperature Applications


M. Parlier, R. Valle, L. Perrière, S. Lartigue-Korinek, L. Mazerolles

Directionally solidified eutectic (DSE) ceramics add new potentialities to the advantages of sintered ceramics: a higher strength, almost constant, up to temperatures close to the melting point and a better creep resistance. The microstructure of melt-growth composites (MGC) of ceramic oxides consists in three-dimensional and continuous interconnected networks of single-crystal eutectic phases. After solidification of binary eutectics, the eutectic phases are alumina and either a perovskite or garnet phase.

10 Years-Activities at Onera on Advanced Thermal Barrier Coatings


M.-P. Bacos, J.-M. Dorvaux, S. Landais, O. Lavigne, R. Mévrel, M. Poulain,
C. Rio, M.-H. Vidal-Sétif

Developing thermal barrier coatings operating at higher temperature and/or for very long durations (commercial aircraft applications) is one of the technological and economic challenges for engine manufacturers. This includes the search for (i)low thermal conductivity, high thermal stability and CMAS resistant ceramic top coats, and (ii)alternative low cost bond coats with improved oxidation resistance and chemical compatibility with the substrate.

Advanced Lightweight Silicide and Nitride Based Materials for Turbo-Engine Applications


S. Drawin, J.F. Justin

Refractory metal silicides and nitride-based ceramics combine two properties
that may lead to substantial reductions in aircraft fuel consumption: compared
to the most advanced nickel-based superalloys presently used in aeronautical

Processing and Characterization of TiAl-based Alloys: Towards an Industrial Scale


M. Thomas, M.-P. Bacos

This paper highlights Onera efforts focused on the design of new TiAl-based alloys, the development of a commercially-viable route for the manufacture of aero engine components and the optimization of mechanical properties. The alloy G4, with a duplex microstructure, has been developed with an excellent balance of properties for gas turbine applications up to 800°C. Additionally, a series of TiAl-3(Fe,Zr,Mo) alloys have been designed for applications with good ductility requirements.

On Some Advanced Nickel-Based Superalloys for Disk Applications


D. Locq, P. Caron

Recent work performed at Onera on nickel-based superalloys for disk
applications is presented. In the first section, disk characteristics and
metallurgical routes used to produce these specific aero-engine components
are reviewed. Then, two alloy development programs carried out to satisfy
the requirements of the industrial partners are detailed. Finally, the results

Performance and Degradation Mechanisms of Thermal Barrier Coatings for Turbine Blades: a Review of Onera Activities


M.-P. Bacos, J.-M. Dorvaux, O. Lavigne, R. Mévrel, M. Poulain, C. Rio,
M.-H. Vidal-Sétif

Thermal barrier coatings are used to protect blades and vanes in the hot
sections of gas turbines. They consist of a thick porous ceramic layer
deposited on a alumina forming metallic bond coat in contact with the nickel-
based superalloy substrate. They are designed to prolong the components
lifetimes or to increase gas temperature, and therefore efficiency. In
service, the structure and composition of the various layers evolve, due to

Ultra High Temperature Ceramics: Densification, Properties and Thermal Stability


J.F. Justin, A. Jankowiak

Hypersonic flights, re-entry vehicles, and propulsion applications all require new materials that can perform in oxidizing or corrosive atmospheres attemperatures in excess of 2000°C and sometimes over the course of a longworking life. Ultra High Temperature Ceramics (UHTCs) are good candidates tofulfill these requirements. Within this family, the ZrB2 and HfB2 based composites are the most attractive.


Accelerated video of a 10 minutes test under high-enthalpy hypersonic flow in the L2K arc-jet facility at DLR Cologne (assessment of performance of a HfB2/SiC/TaSi2 disc at ~1500°C)

Recent Studies at Onera on Superalloys for Single Crystal Turbine Blades


P. Caron, O. Lavigne

Recent alloy development works conducted at Onera for single crystal turbine blade applications succeeded in identifying specific nickel-based superalloys suited for very high temperature applications in aircraft engines and for land-based gas turbine applications in a highly corrosive environment.