A small-angle scattering analysis of the influence of manufacture and thermal induced morphological changes on the thermal conductivity of EB-PVD PYSZ thermal barrier coatings [Elektronische Ressource] / vorgelegt von Arturo Flores Renteria

N.Abarca

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2007
• Nombre de lectures: 7
• Langue: English
• Poids de l'ouvrage: 14 Mo

Extrait

A small-angle scattering analysis of the influence of manufacture and
thermal induced morphological changes on the thermal conductivity of EB-
PVD PYSZ Thermal Barrier Coatings







Von der Fakultät für Georessourcen und Materialtechnik der
Rheinisch -Westfälischen Technischen Hochschule Aachen


zur Erlangung des akademischen Grades eines

Doktors der Ingenieurwissenschaften


genehmigte Dissertation

vorgelegt von Master of Science


Arturo Flores Renteria



aus Moyahua de Estrada – México




Berichter: Univ. Prof. Dr.rer.nat. Wolfgang A. Kaysser
Univ. Prof. Dr.-Ing. Wolfgang Bleck





Tag der mündlichen Prüfung: 11. Januar 2007



Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar
























































Acknowledgments

The present work was originated during my scientific activities in the Institute of Materials
Research (Institut für Werkstoff-Forschung) of the German Aerospace Center (Deutsches
Zentrum für Luft- und Raumfahrt).
I would like to express my deep gratitude to Univ.-Prof. Dr. rer. nat. W.A. Kaysser for giving
me the opportunity of develop my research work in the Institute of Materials Research, and
the scientific tutoring and evaluation of my work as first assessor.
I am very grateful to Univ.-Prof. Dr.-Ing. W. Bleck for his interest and the evaluation of my
work as co-assessor.
I would like to emphasize my gratitude to Dr. habil. Bilge Saruhan-Brings for the scientific
and organizational tutoring of my work.
I am especially thankful to Dr. Ing. U. Schulz for his intensive commitment in the scientific
and technical accomplishment of my work, and Dr. M. Peters for the organizational support to
the execution of my research activities.
My thanks to Dr. H.-J. Rätzer-Scheibe, Dr. Ing. K. Fritscher, and Dr. B. Hildmann for the
important information received during our scientific and technical discussions.
I would like to acknowledge and express gratitude to the exceptional technical support
received during the execution of my research activities by C. Kröder, J. Brien, H. Mangers, R.
Borath, K. Baumann, U. Krebber, and W. Schönau.
I am especially grateful to the colleagues of the High Temperature and Functional Coatings,
and in general to all the personnel working in the Institute of Materials Research for the
pleasant moments during our co-working activities.
I want to acknowledge the intensive support of Dr. J. Ilavsky and P. R. Jemian from the
Intense Advanced Photon Source in Argonne National Laboratory during the USAXS
measurements and the modeling of the data. The use of the Advanced Photon Source was
supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy
Sciences, under Contract No. W-31-109-ENG-38.
I also like to acknowledge the support of Dr. J. Haug and Dr. H. Wiedenmann from the Berlin
Neutron Scattering Center for the measurement and calculations of the polar surface area
distribution via SANS.
At the same time, I would like to acknowledge the support of Dr. C.-K. Loong, Dr. G. Liang,
and D.G. Wozniak from the Intense Pulsed Neutron Source in Argonne National Laboratory
during the surface area change measurements via SANS.
This work was supported by the Consejo Nacional de Ciencia y Tecnología (CONACyT) and
the Deutscher Akademischer Austauschdienst (DAAD). The Deutsches Zentrum für Luft- und
Raumfahrt was additionally involved in the financial sponsoring of the work.

I am most indebted to my beloved wife Nelida for her unconditional support during the
accomplishment of this work.



I
Index

1 Introduction ..................................................................................................................1

2 Background and literature survey..............................................................................5
2.1 Use of TBCs on aircraft gas turbine engines........................................................... 5
2.2 Description of the TBC system ............................................................................... 6
2.3 EB-PVD process...................................................................................................... 8
2.3.1 Fundamentals..................................................................................................... 9
2.3.2 Growth of PYSZ columnar crystals in EB-PVD coatings............................... 10
2.3.3 Microstructure of the EB-PVD coatings ......................................................... 12
2.3.4 Distribution of porosity in EB-PVD coatings ................................................. 14
2.3.5 Influence of process parameters on the microstructure of EB-PVD coatings. 16
2.4 Thermal conductivity............................................................................................. 17
2.4.1 Fundamentals................................................................................................... 17
2.4.2 Thermal conductivity of EB-PVD TBCs ........................................................ 19
2.4.3 Non-interacting approximation modeling of the thermal conductivity
of EB-PVD TBCs 20
2.5 Review of the effect of heat treatments on the morphology and thermal
conductivity of EB-PVD PYSZ TBCs ................................................................. 22
2.6 Sintering phenomena of EB-PVD PYSZ TBCs .................................................... 23

3 Resume of the different themes and motivation of the investigation.....................25

4 Experimental description...........................................................................................27
4.1 Manufacture of the coatings .................................................................................. 27
4.1.1 Materials and physical characteristics of the substrates .................................. 27
4.1.2 Deposition of the bond coats via EB-PVD process......................................... 28
4.1.3 Deposition of the top coats using different parameters conditions via
EB-PVD process (characteristics and equipment) .......................................... 28
4.2 Manufacture of the specimens............................................................................... 30
4.2.1 Specimens for thermal conductivity measurements ........................................ 30
4.2.2 Specimens for SANS-BET measurements ...................................................... 31
4.2.3 Specimens for USAXS measurements ............................................................ 31
4.3 Methods of characterization .................................................................................. 32
4.3.1 Characterization of the porosity ...................................................................... 32
4.3.1.1 Microscopy ................................................................................................ 33
4.3.1.2 Ultrasmall-Angle X-rays Scattering .......................................................... 33
4.3.1.3 Small-Angle Neutron Scattering ............................................................... 38
4.3.1.4 Brunauer-Emmett -Teller Method............................................................. 41
4.3.1.5 Archimedes Method 42
4.3.2 Measurements of the thermal conductivity ..................................................... 43
4.3.2.1 Laser Flash Analysis Method (LFA)......................................................... 43
5 Results..........................................................................................................................48
5.1 Morphology of the five manufactured EB-PVD PYSZ TBCs .............................. 48
5.2 Effect of the sintering phenomena on the morphology of “intermediate”
EB-PVD PYSZ TBCs............................................................................................ 49
5.3 Manufacture and thermally induced morphological changes................................ 53
5.3.1 Results of the microstructural analysis via SANS-BET on five
morphologies ................................................................................................... 53 II
5.3.2 Results of the microstructural analysis via USAXS measurements on
three morphologies .......................................................................................... 55
5.3.2.1 USAXS measurements on coatings in as-coated conditions..................... 55
5.3.2.2 USAXS ments on coatings after ageing conditions 58
5.3.3 Modeling of the USAXS data on three morphologies..................................... 61
5.3.3.1 Modeling of