SURFACE MODIFICATION AND PROTECTION OF ODS-ALLOYS

Información del proyecto

Identificador del acuerdo de subvención: MA1E0012

Proyecto cerrado

Fecha de inicio 1 Enero 1988

Fecha de finalización 31 Diciembre 1990

Financiado con arreglo a

• Research programme (EEC) on materials (raw materials and advanced materials) - Advanced materials (EURAM) -, 1986-1989

Coste total

Sin datos

Aportación de la UE

Sin datos

Coordinado por

NL ORGAN. VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK
Netherlands

Objetivo

ODS-alloys are important metal base alloys for h igh temperature applications such as advanced gas turbines, coal conversion and combined cycle plants. However, it must be protected against oxidation and/or corrosion in an aggressive atmosphrere. FeCrAlY-coatings are, among others, most promising. Composition will change by diffusion of Ni from the substrate and Al from the coating, which results in degradation of the specific coatings properties. The objectives of the research are: - the development of suitable diffusion barriers by CVD or PVD; - improvement of the adhesion of barrier and coating by ion implantation; - improvement of the coating properties by laser beam remelting; - evaluation of the promising coating-substrate materials by laboratory and pilot plant testing.
MA 6000 is an example of an oxide dispersion strengthened (ODS) alloy. Protection by a iron-chromium-aluminium-yttrium coating leads to brittle intermeltings by diffusion of Ni. A diffusion barrier would help. Atmospheric attack could be diminished by sealing of the plasma sprayed coating, which will always contain pores even by spraying under low pressure.

To extend the application of the ODS alloys to more severe conditions, the following details were established regarding coating adhesion and diffusion barrier behaviour:
sputter conditions were established for application of titanium nitride and hafnium nitride coatings on MA 6000 with very good adhesion;
good adhesion of plasma and detonation gun sprayed iron-chromium-aluminium-yttrium coating could be obtained by gradual transition of the titanium nitride and hafnium nitride coatings to metallic titanium and hafnium by decreasing the nitrogen flow during sputtering;
a further improvement of the adhesion of the sputtered layers by ion implantation could not be established;
adhesion was determined by in situ scratch testing;
controlled laser remelting could be obtained under pulsed conditions with a carbon dioxide laser;
pore and crack free surface layers could be obtained up to a depth of 0.12 mm; cracks that formed at the transition from remelted to nonmelted coating disappeared by remelting in succeeding pulses;
during remelting segregation occurred between the metallic and ceramic phase; the much lighter ceramic phase solidified on top of the metallic phase;
the remelted layer exhibited a much better wear resistance at room temperature; short erosion tests at 900 C showed a slight improvement;
long term exposure in a hot salt injected burner rig and in an atmospheric fluid bed combustor pilot plant showed an improved behaviour; presence of cracks was very detrimental.
THE PROJECT WILL BE CARRIED OUT IN 3 PHASES:

1.- THE PILOT PRODUCTION OF A LARGE NUMBER OF DIFFUSION BARRIERS OF SEVERAL TYPES ON SMALL TEST PIECES OF MA 6000. TEST PIECES WILL BE ION IMPLANTED TO MODEIFY THE STRUCTURE OF THE BASE MATERIAL FOR BETTER ADHESION. OTHER PIECES WILL BE ION IMPLANTED TO IMPROVE ADHESION BY ION BEAM MIXING.
2.- THICK CORROSION RESISTANT COATINGS OF FRCRALY WILL BE APPLIED AND COMBINED COATINGS WILL BE TESTED FOR ADHESION. THE LASER BEAM REMELTING EXPERIMENTS WILL BE FOCUSED ON PROMISING SUBSTRATE-BARRIER COATING COMBINATIONS.
3.- THE BEST COATING COMBINATIONS WILL BE SUBMITTED TO MECHANICAL AND CORROSION TESTING ON MA 6000. TENSILE TESTING AND CYCLIC TESTING WILL BE CARRIED OUT. CORROSION EXPERIMENTS ARE ENVISAGED IN CORROSION TEST RIGS AND IN A FBC TEST FACILITY.

THE APPLICABILITY OF HIGH STRENGTH MATERIALS IN AGGRESSIVE ENVIRONMENTS BY THE USE OF SUITABLE COATING TECHNIQUES IS A KEY ASPECT IN THE FURTHER DEVELOPMENT OF ADVANCED GAS TURBINES, COAL CONVERSION AND COMBINED CYCLE PLANTS, AND MAY ELIMINATE THE LIMITATIONS ENCOUNTERED IN SEVERAL OTHER PROCESS INSTALLATIONS. THIS WILL LEAD TO SUBSTANTIAL ECONOMICAL BENEFITS.
TECHNOLOGICAL BENEFITS ARE RELATED TO THE DEVELOPMENT OF SUITABLE DIFFUSION BARRIERS, WHICH CAN BE APPLIED BY WELL KNOWN TECHNIQUES AND THE IMPROVEMENT IN THE ADHESION OF THE DIFFUSION BARRIER COATINGS AND THEIR CORROSION PROPERTIES BY ION IMPLANTATION TECHNIQUES, WHICH CAN ALSO BE USED FOR JOINING CERAMICS AND METALS.

Ámbito científico (EuroSciVoc)

• ciencias naturales › ciencias químicas › química inorgánica › metales de transición
• ingeniería y tecnología › ingeniería ambiental › energía y combustibles › energía fósil › carbón
• ingeniería y tecnología › ingeniería de materiales › recubrimiento y películas
• ingeniería y tecnología › ingeniería de materiales › cerámica
• ciencias naturales › ciencias físicas › óptica › física del láser

Programa(s)

• FP1-EURAM - Research programme (EEC) on materials (raw materials and advanced materials) - Advanced materials (EURAM) -, 1986-1989

Tema(s)

Datos no disponibles

Convocatoria de propuestas

Datos no disponibles

Régimen de financiación

CSC - Cost-sharing contracts

Coordinador

NL ORGAN. VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK

• Aportación de la UE: Sin datos
• Dirección: LAAN VAN WESTENENK 301 ; 7334 DT APELDOORN ; Países Bajos
• Coste total: Sin datos

Participantes (2)

STUDVIK ENERGITEKNIK

Suecia

• Aportación de la UE: Sin datos
• Coste total: Sin datos

UNIVERSITY OF TAMPERE

• Aportación de la UE: Sin datos
• Coste total: Sin datos