Aeronáutica

URI permanente para esta comunidadhttps://digitalpro.inta.es/handle/20.500.12666/37

Muchas de las líneas de investigación del INTA se centran en el ámbito aeronáutico. Estas líneas van encaminadas a reforzar las competencias en nuevas tecnologías, haciendo especial hincapié a las relacionadas con caracterización de emisiones producidas por turborreactores, investigación en tecnologías del hidrógeno y otras energías renovables, motores cohete con propulsante líquido y sólido, estudio de materiales funcionales, diseño y fabricación de superficies hielofóbicas, recubrimientos protectores para la corrosión por biomasa, estructuras activas avanzadas y robótica, generación avanzada de trayectorias sobre UAVs, aprendizaje automático e inteligencia artificial sobre minería de datos aerodinámicos y actuadores de plasma y sus aplicaciones.

La investigación de la Aeronáutica se materializa en proyectos financiados con fondos propios, como por ejemplo GERD, que trata del estudio de las condiciones y las tipologías de formación de hielo en superficies. Actualmente se están finalizando las tareas de implementación del nuevo de viento de engelamiento, único en el país, duplicando la capacidad de realización de ensayos en condiciones de formación de hielo.

En el sector aeronáutico del INTA cabe destaca el CIAR, un centro de ensayos en vuelo innovador, que proporciona apoyo técnico y logístico en la experimentación de sistemas de vuelo no tripulados en el ámbito de operación civil o dual y el CEDEA, un centro de ensayos para caracterización de aeronaves y sus componentes tanto tripuladas como no tripuladas, experimentación de misiles, cohetes e I+D de proyectos aeronáuticos de energía y estudio de la atmósfera.

Otros campos de investigación relacionados con la Aeronáutica son la tecnología del vuelo, la aerodinámica teórica y experimental, materiales y estructuras, desarrollo de pinturas, estudio de nuevas fuentes de energía, con programas de I+D dentro del campo de la propulsión y de su aplicación aeroespacial, estudio del impacto medioambiental de los propulsantes y trabajos relacionados con los combustibles y lubricantes en el ámbito aeroespacial y de la Defensa Nacional.

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Mostrando 1 - 20 de 128

Acceso Abierto
10,000 h molten salt corrosion testing on IN617, uncoated and aluminide ferritic steels at 580 ºC
(Richter C., 2020-12) Agüero, Alina; Audigié, Pauline; Sergio, Rodríguez Catela; European Commission (EC)
Long term testing of two ferritic-martensitic steels (P91 and VM12-SHC) with and without slurry deposited aluminide coatings containing 20 wt.% of Al at the surface was carried out by exposing these materials to the Solar Salt, a eutectic mixture composed of 60 % NaNO3 - 40 % KNO3 at 580ºC. This salt is currently used in operating thermal solar power plants as heat transfer and storage fluid. Tubes made of expensive Ni based alloys are employed to mitigate corrosion. The tested uncoated ferritic materials exhibited very high corrosion rates developing thick, easily detached scales. IN617 was also tested as a reference and experienced very low corrosion up to 5,000 h, but after 10,000 h a 50 ȝm thick, mostly NiO scale had developed with Na0.6CoO2 crystals deposited on top. There was also evidence of significant Cr depletion at the alloy surface. Carcinogenic CrVI was found in the Solar Salt melt in which the three uncoated alloys were immersed. In contrast, the two coated ferritic steels did not show evidence of degradation after 10,000 h and the most significant microstructural change was the development of a very thin protective NaAlO2 layer on their surface. An industrial process to deposit these coatings on the inner surfaces of pipes has already been developed.
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A chamber for studying planetary environments and its applications to astrobiology
(IOP Science Publishing, 2006-07-13) Mateo Marti, Eva; Prieto-Ballesteros, Olga; Sobrado, J. M.; Gómez Elvira, J.; Martín Gago, J. A.; Instituto Nacional de Técnica Aeroespacial (INTA); Comunidad de Madrid
We have built a versatile environmental simulation chamber capable of reproducing atmospheric compositions and surface temperatures for most of the planetary objects. It has been especially developed to make feasible in situ irradiation and characterization of the sample under study. The total pressure in the chamber can range from 5 to 5 × 10−9 mbar. The required atmospheric composition is regulated via a residual gas analyser with ca ppm precision. Temperatures can be set from 4 K to 325 K. The sample under study can be irradiated with ion and electron sources, a deuterium ultraviolet (UV) lamp and a noble-gas discharge UV lamp. One of the main technological challenges of this device is to provide the user the possibility of performing ion and electron irradiation at a total pressure of 0.5 mbar. This is attained by means of an efficient differential pumping system. The in situ analysis techniques implemented are UV spectroscopy and infrared spectroscopy (IR). This machine is especially suitable for following the chemical changes induced in a particular sample by irradiation in a controlled environment. Therefore, it can be used in different disciplines such as planetary geology, astrobiology, environmental chemistry, materials science and for instrumentation testing.
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A comparative analysis of helicopter recovery maneuvers on a SFS by means of PIV and balance measurements
(Elsevier, 2023-05-23) Matías García, J. C.; Rafael, Bardera Mora; Franchini, Sebastián; Barroso, Estela; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)
The flow field around a frigate is complex due to flow detachments, high velocity gradients, and flow unsteadiness. These flow patterns can endanger helicopter operations around frigates and increase pilot workload above the flight deck. This paper contains a comparative analysis of three different recovery maneuvers: an approach from the stern in the centerline plane (S); a diagonal maneuver (D); and an L-shaped maneuver. The comparison is made using wind tunnel tests with a scaled frigate and a motorized helicopter. For the three maneuvers, velocity contours around the helicopter with Particle Image Velocimetry are obtained. An internal balance is also used to obtain forces and moments on the helicopter during the flight path of the maneuvers. Those measurements show that the wake of the ship mostly affects longitudinal and thrust forces. In addition, pitch torque is highly reduced when the helicopter is behind the frigate superstructure, and the roll moment is also important when the wind angle increases. In the end, an estimation of pilot workload is presented to conclude that L-shaped maneuver is the best for 0° and small WOD angles and D or S recoveries for moderately high negative WOD angles.
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A Comparative Study on HCN Polymers Synthesized by Polymerization of NH4CN or Diaminomaleonitrile in Aqueous Media: New Perspectives for Prebiotic Chemistry and Materials Science
(Chemistry Europe: European Chemical Societies Publishing, 2019-08-02) Ruiz-Bermejo, Marta; de la fuente, Jose Luis; Carretero González, J.; García Fernández, L.; Rosa Aguilar, M.; Agencia Estatal de Investigación (AEI); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
HCN polymers are a group of complex and heterogeneous substances that are widely known in the fields of astrobiology and prebiotic chemistry. In addition, they have recently received considerable attention as potential functional material coatings. However, the real nature and pathways of formation of HCN polymers remain open questions. It is well established that the tuning of macromolecular structures determines the properties and practical applications of a polymeric material. Herein, different synthetic conditions were explored for the production of HCN polymers from NHCN or diaminomaleonitrile in aqueous media with different concentrations of the starting reactants and several reaction times. By using a systematic methodology, both series of polymers were shown to exhibit similar, but not identical, spectroscopic and thermal fingerprints, which resulted in a clear differentiation of their morphological and electrochemical properties. New macrostructures are proposed for HCN polymers, and promising insights are discussed for prebiotic chemistry and materials science on the basis of the experimental results.
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A comparison of helicopter recovery maneuvers on frigates by means of PIV measurements
(Elsevier, 2021-01-21) Rafael, Bardera Mora; Matías García, J. C.
"Helicopter pilots who have to operate on frigates must deal with turbulent and unsteady flows caused by the incidence of the wind on the non-aerodynamic surfaces of the frigate. In addition, the flight deck is usually placed at the stern, right behind the frigate superstructure where recirculation and low-velocity regions appear. For that reason, studying how the aerodynamic effects influence the helicopter rotor during the approach and landing on the frigate could be essential to guarantee safe operations. The aim of this paper is to present PIV velocity maps with the flow patterns generated by the interaction between the frigate wake and the helicopter rotor working during its landing approach usually named as dynamic-interface. Three different landing maneuvers have been analyzed: rear, diagonal and aft-fore. The jet generated by the rotor will be used to obtain induced velocity profiles under the rotor. With these velocity profiles, rotor asymmetries during its working over the frigate are detected. With all data at each point of the maneuvers, a final comparison will be made to select the best procedure for helicopter recovery on frigates under different wind over deck conditions."
Acceso Abierto
A direct comparative study of the corrosion behaviour of Si-free and Si-rich slurry aluminide coatings in molten carbonate melts
(LNEG Laboratorio Nacional de Energia e Geologia, 2022-11-24) Audigié, Pauline; Sergio, Rodríguez Catela; Agüero, Alina; Pedrosa, Fátima; Paiva, Teresa; Diamantino, Teresa
ABSTRACT: This study is focused on the evaluation of the hot corrosion behaviour of two low-cost slurry aluminide coatings with and without Si addition deposited on ferritic-martensitic steels, comparing them with uncoated steel, after 1000-h of exposure to Li, K, Na molten carbonates at 650ºC, under static and dynamic conditions with a high linear velocity (1.3 m/s). Both coatings evidenced a high performance increase in comparison with uncoated substrates after exposure in both conditions. Both coatings behaved in a similar way according to the gravimetric results. However, after dynamic exposure, the Si-free aluminide maintained its morphology and composition after 1000 h with α-LiAlO2 as the only corrosion product while the Si-rich coating showed a higher attack extent in the outer part and developed a large quantity of voids at the coating/substrate interface, leading to substrate corrosion.
Acceso Abierto
A dual perspective on the microwave-assisted synthesis of HCN polymers towards the chemical evolution and design of functional materials
(Nature Research Journals, 2020-12-18) Hortal, Lucia; Pérez Fernández, Cristina; de la fuente, Jose Luis; Valles González, M. P.; Mateo Marti, Eva; Ruiz-Bermejo, Marta; Instituto Nacional de Técnica Aeroespacial (INTA); Agencia Estatal de Investigación (AEI); http://dx.doi.org/10.13039/501100011033; http://dx.doi.org/10.13039/501100010687; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
In this paper, the first study on NH4CN polymerization induced by microwave radiation is described, where a singular kinetic behaviour, especially when this reaction is conducted in the absence of air, is found. As a result, a complex conjugated N-heterocyclic polymer system is obtained, whose properties are very different, and even improved according to morphological features, characterized by their X-ray diffraction patterns and scanning electron microscopy analysis, with respect to those produced under conventional thermal treatment. In addition, a wide variety of relevant bioorganics have been identified, such as amino acids, nucleobases, co-factors, etc., from the synthetized NH4CN polymers. These particular families of polymers are of high interest in the fields of astrobiology and prebiotic chemistry and, more recently, in the development of smart multifunctional materials. From an astrobiological perspective, microwave-driven syntheses may simulate hydrothermal environments, which are considered ideal niches for increasing organic molecular complexity, and eventually as scenarios for an origin of life. From an industrial point of view and for potential applications, a microwave irradiation process leads to a notable decrease in the reaction times, and tune the properties of these new series macromolecular systems. The characteristics found for these materials encourage the development of further systematic research on this alternative HCN polymerization.
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A simple lab screening test to evaluate ice adhesion
(Elsevier, 2025-09) García, Paloma; Mora, Julio; Agüero, Alina; Ministerio de Economía y Competitividad (MINECO)
Ice formation is a major problem for many sectors such as aeronautics, power generation, maritime, communications, etc. and therefore, there is a growing demand for anti-icing surface modification technologies. Being able to compare and evaluate these materials at the laboratory scale is a challenge for which a unified response has not yet been given. There are no standards for evaluating icephobicity despite the fact that there are numerous studies focused on the influence of the surface topography on the wetting behavior. In addition, several testing options have been published both for the evaluation of ice accretion, mainly focused on ice wind tunnels (IWT), and on ice to substrate adhesion, as for instance the zero degree cone test, DLST, Cantilever, centrifugal tests, etc. This article describes a method developed to carry out a simple screening evaluation of ice adhesion by the double lap shear test (DLST) method. This technique can provide qualitative ice adhesion information and is commonly available in research laboratories. Moreover, it does not require icing wing tunnel testing. Its ease of execution and reproducibility makes it a useful tool for a first stage evaluation of anti-icing surfaces despite the fact that ice is formed under static conditions. Various materials and surface finished surfaces with different degree of ice adhesion strength were evaluated and were also tested in a centrifugal adhesion test with ice accreted in an IWT. The results showed that the DLST is valid for ice adhesion classification of materials, but shows limitations for those superhydrophobic materials that are in the Cassie-Baxter state.
Acceso Abierto
A slurry coating for Cd replacement for aircraft components
(Mondragon Unibertsitatea, 2008-07-25) Agüero, Alina; Blanco, C; Gutiérrez del Olmo, Marcos; García Martínez, María
Acceso Abierto
Adhesives Based on Poly(glycidyl methacrylate-co-butyl acrylate) with Controlled Structure: Curing Behavior and Adhesion Properties on Metal Substrates
(Wiley, 2023-10-26) Cañamero, Pedro; Fernández García, Marta; de la fuente, Jose Luis; Ministerio de Ciencia e Innovación (MICINN); Instituto Nacional de Técnica Aeroespacial (INTA)
The adhesion properties of poly(glycidyl methacrylate (GMA)-co-butyl acrylate (BA)) statistical copolymers, synthesized by atom transfer radical polymerization (ATRP), are investigated employing three different curing agents or hardeners, such as diethanolamine (DEA), dicyandiamide (DICY), and 2-cyanoacetamide (2-CA) on copper, iron, brass, aluminum, and titanium metal surfaces. This work describes the treatment of the different surfaces, establishes the optimal curing conditions from differential scanning calorimetry (DSC) analysis of these novel adhesive systems, and evaluates the results of the single-lap shear test for metal joints. Thus, by dynamic DSC measurements of the mixtures, a low curing temperature of 90 °C is defined when DEA is used as a curative; while systems based on DICY and 2-CA require temperatures of 150 °C and 160 °C, respectively. In addition, the curing process of this controlled acrylic copolymer with DICY exhibits a singular behavior, possibly due to the curing reaction mechanism, where multiple epoxy-amine ring-opening polyaddition reactions take place between DICY's active hydrogens and epoxy groups of poly(GMA-co-BA). This latter curing system shows the highest adhesion features with lap-shear strength at room temperature of 15.5 MPa, using copper as metallic substrate; however, the best results are obtained using 2-CA as curing agent with aluminum and iron.
Acceso Abierto
Aerodynamic investigation of a morphing wing for micro air vehicle by means of PIV
(MDPI, 2020-10) Rafael, Bardera Mora; Rodríguez Sevillano, A.; García-Magariño, Adelaida; Ministerio de Defensa; García Magariño, A. [0000-0002-6039-8407]
A wind tunnel tests campaign has been conducted to investigate the aerodynamic flow around a wing morphing to be used in a micro air vehicle. Non-intrusive whole field measurements were obtained by using PIV, in order to compare the velocity and turbulence intensity maps for the modified and the original version of an adaptive wing designed to be used in a micro air vehicle. Four sections and six angles of attack have been tested. Due to the low aspect ratio of the wing and the low Reynold number tested of 6.4 × 104, the influence of the 3D effects has been proved to be important. At high angles of attack, the modified model prevented the detachment of the stream, increased the lift of the wing and reduced the turbulence intensity level on the upper surface of the airfoil and in the wake.
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Al Slurry Coatings for Molten Carbonate Fuel Cell Separator Plates
(Scientific.Net, 2001-01-20) Agüero, Alina; García, M. C.; Muelas Gamo, Raúl; Sánchez, A.; Pérez, Francisco J.; Duday, David; Hierro, M. P.; Gómez, Consuelo
The corrosion behaviour of Al slurry coated AISI 310 stainless steel, with and without diffusion heat treatment, was investigated as a wet seal material for molten carbonate fuel cell (MCFC) at 650°C. The results were compared with IVD Al coated AISI 310. Characterization of the samples before and after exposure to the eutectic 62 mol% Li2CO3-38 mol% K2CO3 mixture at 650°C for 1000 h by SEM-EDS and XRD was carried out. The presence of LiAlO2 on the coated samples was confirmed by XRD. The slurry Al-coated stainless steels performed at least as well as the IVD Al coating.
Acceso Abierto
Aluminide Coatings by Means of Slurry Application: A Low Cost, Versatile and Simple Technology
(MPDI, 2024-09-29) Agüero, Alina; Audigié, Pauline; Lorente Sánchez, Cristina; Gutiérrez del Olmo, Marcos; Mora, Julio; Sergio, Rodríguez Catela; European Commission; Agencia Estatal de Investigación (España)
The present study focused on demonstrating the versatility of the slurry deposition technique to produce aluminide coatings to protect components from high-temperature corrosion in a broad temperature range, from 400 to 1400 °C. This is a simpler and low-cost coating technology used as an alternative to CVD and pack cementation, which also allows the coating of complex geometries and offers improved and simple repairability for a lot of industrial applications, along with avoiding the use of non-hazardous components. Slurry aluminide coatings from a proprietary water-based-Cr6+ free slurry were produced onto four different substrates: A516 carbon steel, 310H AC austenitic steel, Ti6246 Ti-based alloy and TZM, a Mo-based alloy. The resulting coatings were thoroughly characterised by FESEM and XRD, mainly so that the identification of microstructures and appropriate phases was reported for each coating. The importance of surface preparation and heat treatment as key parameters for the coating final microstructures was also evidenced, and how those parameters can be optimised to obtain stable intermetallic phases rich in Al to sustain the formation of a protective Al2O3 oxide scale. These coating systems have applications in diverse industrial environments in which high-temperature corrosion limits the lifetime of the components.
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Aluminum slurry coatings to replace cadmium for aeronautic applications
(Elsevier, 2012-10-27) Agüero, Alina; del Hoyo Gordillo, Juan Carlos; García de Blas, Javier; García, M.; Gutiérrez, M.; Madueño, L.; Ulargui, S.
Cadmium has been widely used as a coating to provide protection against galvanic corrosion for steels and for its natural lubricity on threaded applications. However, it is a toxic metal and a known carcinogenic agent, which is plated from an aqueous bath containing cyanide salts. For these reasons, the use of cadmium has been banned in Europe for most industrial applications. However, the aerospace industry is still exempt due to the stringent technical and safety requirements associated with aeronautical applications, as an acceptable replacement is yet to be found. Al slurry coatings have been developed as an alternative to replace cadmium coatings. The coatings were deposited on AISI 4340 steel and have been characterized by optical and electron microscopy. Testing included salt fog corrosion exposure, fluid corrosion exposure (immersion), humidity resistance, coating-substrate and paint-coating adhesion, electric conductivity, galvanic corrosion, embrittlement and fatigue. The results indicated that Al slurry coatings are an excellent alternative for Cd replacement.
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Analysis of void formation in Pt-rich γ-γ’ bond-coatings for TBC system application
(Elsevier, 2025-02-21) Audigié, Pauline; Vande Put, Aurélie; Malard, Benoit; Malié, André; Monceau, Daniel
Pt-rich γ-γ’ bond-coatings for thermal barrier coating systems may lead to detrimental pore formation. An extensive analysis of literature on voids nucleation and growth in the different metallic components of several kinds of TBC systems was performed. The study then focused on Pt-rich γ-γ’ bond-coating/Ni-based superalloy systems employing an original statistical analysis of voids formation and spatial distribution through secondary electron microscopy with focused ion beam sequential cross sectioning and synchrotron X-Ray tomography. It was found that pores at the Pt-rich γ-γ’ bond-coating/superalloy interface form due to the Kirkendall effect, with the highest concentration located at the Pt diffusion front.
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Analytic adjoint solution for incompressible potential flows
(AIP Publishing, 2025-06-10) Lozano, Carlos; Ponsin Roca, Jorge; Instituto Nacional de Técnica Aeroespacial (INTA)
We obtain the analytic adjoint solution for two-dimensional incompressible potential flow for a cost function measuring aerodynamic force using the connection of the adjoint approach to Green's functions and also by establishing and exploiting its relation to the adjoint incompressible Euler equations. By comparison with the analytic solution, it is shown that the naïve approach based on solving Laplace's equation for the adjoint variables can be ill-defined. The analysis of the boundary behavior of the analytic solution is used to discuss the proper formulation of the adjoint problem as well as the mechanism for incorporating the Kutta condition in the adjoint formulation.
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Analytic adjoint solutions for the 2-D incompressible Euler equations using the Green's function approach
(Cambridge University Press, 2022-06-13) Lozano, Carlos; Ponsin Roca, Jorge; Instituto Nacional de Técnica Aeroespacial (INTA)
The Green's function approach of Giles and Pierce (J. Fluid Mech., vol. 426, 2001, pp. 327–345) is used to build the lift and drag based analytic adjoint solutions for the two-dimensional incompressible Euler equations around irrotational base flows. The drag-based adjoint solution turns out to have a very simple closed form in terms of the flow variables and is smooth throughout the flow domain, while the lift-based solution is singular at rear stagnation points and sharp trailing edges owing to the Kutta condition. This singularity is propagated to the whole dividing streamline (which includes the incoming stagnation streamline and the wall) upstream of the rear singularity (trailing edge or rear stagnation point) by the sensitivity of the Kutta condition to changes in the stagnation pressure.
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Anomalous steam oxidation behavior of a creep resistant martensitic 9 wt. % Cr steel
(Elsevier, 2013-06-09) Agüero, Alina; González, Vanessa; Mayr, Peter; Spiradek Hahn, Krystina; Ministerio de Economía y Competitividad (MINECO)
The efficiency of thermal power plants is currently limited by the long-term creep strength and the steam oxidation resistance of the commercially available ferritic/martensitic steel grades. Higher operating pressures and temperatures are essential to increase efficiency but impose important requirements on the materials, from both the mechanical and chemical stability perspective. It has been shown that in general, a Cr wt. % higher than 9 is required for acceptable oxidation rates at 650 °C, but on the other hand such high Cr content is detrimental to the creep strength. Surprisingly, preliminary studies of an experimental 9 wt. % Cr martensitic steel, exhibited very low oxidation rates under flowing steam at 650 °C for exposure times exceeding 20,000 h. A metallographic investigation at different time intervals has been carried out. Moreover, scanning transmission electron microscopy (STEM) analysis of a ground sample exposed to steam for 10,000 h at 650 °C revealed the formation of a complex tri-layered protective oxide comprising a top and bottom Fe and Cr rich spinel layer with a magnetite intermediate layer on top of a very fine grained zone.
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Applications of Quasicrystalline materials as Thermal Barriers in Aeronautics and Future Perspective ofUse for these Materials
(Springer, 1998-05-05) Sánchez, A.; García de Blas, Javier; Algaba, J. M.; Álvarez, J.; Vallés González, Pilar; García Poggio, M. C.; Agtiero, A.
Quasicrystalline materials (QCs) have very interesting properties which make them good candidates to be used as coatings resistant to wear, high temperature oxidation, corrosion, etc. the potential application of AI71Co13Fe8Co8 (QC1), a quasicrystalline approximant alloy, as a thermal barrier coating (TBC) for components of aeronautical and power generation turbines was explored in our laboratories and the results are presented in this paper. QC1 is stable at I 1000°C and has a thermal conductivity similar to that of yttria stabilized zirconia (YSZ), the most commonly used material for TBCs. QC1 powders were low pressure plasma sprayed on IN100 superalloy and coatings of excellent quality were obtained after a series of optimization experiments. the “as deposited” coatings were characterized by XRD, SEM and TEM and the results indicated that the coatings retained the same microstructure and phase composition as the bulk material. However, when coated specimens were heat treated at 950°C, interdifussion between coating and substrate took place resulting in the transformation of the QC approximant phase. To avoid or retard this process, the effect of several diffussion barrier layers, deposited between substrate and coating, was studied and the results showed that some of these barriers were quite efficient in slowing the diffusion process. Extensive cyclic oxidation and hot corrosion studies were carried out, showing promising results for this new type of TBC coatings. A short term ground engine test was carried out with coated blades.
Acceso Abierto
Behaviour of coated and uncoated ferritic steels under isothermal and cyclic steam oxidation conditions
(VTT, 2007-06-14) Agüero, Alina; González, Vanessa; Gutiérrez, M.
Next generation steam turbines are expected to operate at 600-650°C and at these temperatures, currently available high strength ferritic-martensitic steels need to be coated to prevent oxidation. Slurry deposited aluminide coatings have shown excellent performance up to 650°C under isothermal conditions. The behaviour of these coatings as well as that of uncoated P92 under thermal cycling conditions has been studied both in steam and in air at 650°C. The tested specimens were characterized by field emission scanning electron microscopy. A comparison with isothermal steam oxidation has been established. In cyclic oxidation, evidence of scale spallation from uncoated substrates was observed at shorter exposure times than for specimens tested under isothermal conditions. In the coated specimens, cracks originally present in the "as deposited" coating did not propagate or become sites of preferential oxidation during isothermal steam testing. However, the cracks widened and propagated causing substrate oxidation when the specimens were tested by thermal cycling in steam or in air.

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