High temperature properties of AlN coatings deposited by chemical vapor deposition for solar central receivers

D. Chen (1) , J. Colas , Michel Pons (1) , Frédéric Mercier (1) , R. Boichot (1) , L. Charpentier (2) , C. Escape (2) , M. Balat-Pichelin (2)

1 SIMaP - Science et Ingénierie des Matériaux et Procédés
2 PROMES - Procédés, Matériaux et Energie Solaire

There is an increasing interest for tower concentrated solar power (CSP) systems which can work at temperatures higher than 1073 K to optimize the efficiency. One of the challenges is to design the receiver that will be heated at high temperatures. On the contrary to coatings in gas turbine engine, the coating/substrate system must have a high thermal conductivity to ensure a good heat transfer to the fluid. Aluminum nitride (AlN) coating, deposited by chemical vapor deposition at 1373 K at a growth rate of 10-50 µm h-1 , was selected for its high thermal conductivity, low thermal expansion coefficient, high temperature stability and its ability to develop stable alumina scales above 1273 K. Cast and ODS (Oxide Dispersion Strengthened) FeCrAl alloys, also alumina-formers, were chosen as model substrates to reduce the influencing parameters in real-life receivers and to study the potential of these coatings. Accelerated cyclic oxidation tests and emissivity measurements allowed the evaluation of AlN coatings as materials for high temperature CSP receivers. The multilayered systems showed low degradation after hundreds of thermal cycles at 1073 K in air and can support higher temperatures (1373 K) for 100 to 500 h depending on the coating thickness. Nevertheless the fast cyclic oxidations in solar furnace generated cracks through the coatings. The measurement of the optical properties also revealed a decrease of the absorptivity after oxidation.

Domaines: Matériaux

D. Chen, J. Colas, Michel Pons, Frédéric Mercier, R. Boichot, et al.. High temperature properties of AlN coatings deposited by chemical vapor deposition for solar central receivers. Surface and Coatings Technology, 2019, 377, pp.124872. ⟨10.1016/j.surfcoat.2019.07.083⟩. ⟨hal-02906185⟩