Search and development activities – and results in surface treatment, aluminizing, oxydation, thermal spray and so on – have been included in more than 70 papers published at international conferences and technical congresses.

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2024

Surface and Coatings Technology

Volume 476, 30 January 2024, 130270

The effect of ceramic YSZ powder morphology on coating performance for industrial TBCs

Simone Bursich a, Stefania Morelli b, Giovanni Bolelli b c d, Greta Cavazzini a, Edoardo Rossi e, Francesco Gerardo Mecca b, Salvatore Petruzzi b, Edoardo Bemporad e, Luca Lusvarghi b c d

Abstract:

The increasing turbine inlet temperatures in modern gas turbines have raised concerns about the corrosion of ceramic thermal barrier coatings (TBCs) caused by molten silicate deposits, commonly referred to as “CMAS” due to their main constituents (CaO-MgO-Al2O3-SiO2). The objective of this study was to investigate the combined influence of powder morphology and chemical composition on the CMAS resistance and thermal cycling resistance of ceramic monolayer and bi-layer coatings created through Atmospheric Plasma Spraying (APS). Three powder morphologies were examined: porous Agglomerated and Sintered (A&S) granules, Hollow Spherical (HOSP) powders, and dense, irregular Fused and Crushed (F&C) particles. Monolayer 7-8YSZ coatings with both porous and dense vertically cracked (DVC) microstructures, and bi-layer coatings consisting of a bottom layer of porous standard 7-8YSZ and a top layer composed of a porous high‑yttrium ZrO2–55 wt% Y2O3 were obtained using all three powder types (A&S, HOSP, or F&C). Furthermore, the bi-layer systems were deposited with different ratios between the individual layer thicknesses and/or different total thickness. FEG-SEM, EDX, and micro-Raman analyses, were conducted to assess the coatings’ performance. Nanoindentation high-speed mapping and pillar splitting test were performed to evaluate the mechanical behaviour. The study on 8YSZ monolayers shows that coatings from a F&C feedstock exhibit higher density, reducing the CMAS penetration. However, these coatings demonstrate poorer thermal cycling performance due to increased stiffness and thermal stresses. Coatings from HOSP and A&S powders allow CMAS penetration but offer stress relief pathways, enhancing the coating’s ability to withstand thermal stresses. Bi-layer coatings with a 55YSZ top coat show superior CMAS resistance compared to 7-8YSZ monolayer coatings, with limited penetration causing top coat peeling. The thickness ratio between the layers also affects thermal cycling resistance, where a thinner 55YSZ layer extends the TBC lifetime.

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Surface and Coatings Technology

Volume 439, 15 June 2022, 128433

Original Article

CMAS corrosion and thermal cycling fatigue resistance of alternative thermal barrier coating materials and architectures: A comparative evaluation

StefaniaMorelliaSimoneBursichabVeronicaTestaaGiovanniBolelliacdAlessandroMiccichèaLucaLusvarghiacd

Abstract:

The corrosion of ceramic thermal barrier coatings (TBCs) by molten silicate deposits, usually known as “CMAS” from their main constituents (CaO-MgO-Al2O3-SiO2), is an issue of increasing concern in modern gas turbines as the turbine inlet temperatures are increased to enhance thermodynamic efficiency. Because conventional ZrO2-7wt%Y2O3 (7YSZ) dissolves quite readily in a CMAS melt, many alternative materials have been proposed, but there are not many comparative studies among them. Multi-layer architectures featuring a tougher 7YSZ bottom layer and a more brittle, but more CMAS corrosion-resistant top layer have also been proposed; therefore, a comparison among these architectures is also in order. In this paper we studied comparatively the resistance to CMAS corrosion and to thermal cycling fatigue (an essential pre-requisite for any TBC system) of Gd2Zr2O7, ZrO2–55wt%Y2O3 and Gd/Yb/Y co-doped ZrO2, both in the form of single, dense-vertically cracked (DVC) layers deposited by plasma spraying onto an MCrAlY bond coat, and as top layers with a bottom layer of either porous or DVC 7YSZ. It was found that Gd2Zr2O7 resists CMAS corrosion, without any grain-boundary dissolution, slightly better than does ZrO2–55wt%Y2O3. They both develop a solid Gd- or Y-apatite layer (respectively) at the interface with the CMAS melt, driven by the rather large difference in optical basicity between these compounds and CMAS itself, but the Y-apatite layer is less continuous and, therefore, a bit less protective. Gd/Yb/Y co-doped ZrO2, instead, suffers as much grain-boundary dissolution in contact with molten CMAS as does 7YSZ. A Gd2Zr2O7/porous 7YSZ system would therefore exhibit simultaneously high resistance to CMAS dissolution and to thermal cycling fatigue, although there is a risk that the CMAS melt might infiltrate the segmentation macro-cracks and the microcracks of the Gd2Zr2O7 layer and undermine the porous 7YSZ bottom layer.

Journal of the European Ceramic Society
Volume 40, Issue 12, September 2020, Pages 4084-4100

Original Article
CMAS corrosion of YSZ thermal barrier coatings obtained by different thermal spray processes

Abstract
Degradation of yttria-stabilized zirconia (YSZ) layers by molten CaO-MgO-Al2O3-SiO2 (CMAS)-based deposits is an important failure mode of thermal barrier coating (TBC) systems in modern gas turbines. The present work aimed to understand how the chemical purity and microstructure of plasma-sprayed YSZ layers affect their response to CMAS corrosion. To this end, isothermal corrosion tests (1 h at 1250 °C) were performed on four different kinds of YSZ coatings: atmospheric plasma-sprayed (APS) layers obtained from standard- and high-purity feedstock powders, a dense – vertically cracked (DVC) layer, and a suspension plasma sprayed (SPS) one. Characterization of corroded and non-corroded samples by FEG-SEM, EBSD and micro-Raman spectroscopy techniques reveals that, whilst all YSZ samples suffered grain-boundary corrosion by molten CMAS, its extent could vary considerably. High chemical purity limits the extent of grain-boundary dissolution by molten CMAS, whereas high porosity and/or fine crystalline grain structure lead to more severe degradation.

CMAS corrosion of conventional plasma sprayed (APS), dense-vertically cracked (DVC) and suspension plasma sprayed (SPS) YSZ thermal barrier coatings (TBCs),
Les Rencontres Internationales de la Projection Thermique, 9th RIPT Conference 11th-13th December 2019, Forschungszentrum Jülich
S. Morelli, N. Antolotti, G. Bolelli, O. Ligabue, L. Lusvarghi, E. Molinari, L. Righi, V. Testa

Industrial application of suspension plasma spray:  are we going in the right direction?
TSE4E 2019, Therma Spray of Suspension and Solution Symposium + EBCs, September 2019, Boucherville, Canad
Ligabue, S. Bursich

High-temperature erosion of suspension plasma sprayed thermal barrier coatings
Oral Contribution XV Convegno AIMAT 2019, July 2019, Ischia, Italy
S. Morelli, N. Antolotti, G. Bolelli, O. Ligabue, L.  Lusvarghi, F. Marra, P. Puddu, G. Pulci, F. Sarasini, V. Testa

Suspension Plasma Spray: industrial developments and characterizations for gas turbine components
Oral Contribution ITSC2019, June 2019, Yokohama, Japan
O. Ligabue, N. Antolotti, S. Bursich, S. Morelli, G. Bolelli, L.  Lusvarghi, F. Marra, G. Pulci, F. Sarasini

Damage progression in thermal barrier coating systems during thermal  cycling: a nano-mechanical assessment
Materials and Design, Jan. 2019, 107615
Giovanni Bolelli1*, Maria Grazia Righi1, Muhammad Zeeshan Mughal2, Riccardo Moscatelli2, Omar Ligabue3, Nelso Antolotti3, Marco Sebastiani2, Luca Lusvarghi1, Edoardo Bemporad2
1 Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Pietro Vivarelli 10/1, I-41125 Modena, MO, Italy, 2 Roma Tre University, Engineering Department, Via della Vasca Navale 79, 00146 Rome, Italy, 3 Turbocoating S.p.A., via Mistrali 7, I-43043 Rubbiano di Solignano, PR, Italy

Suspension Plasma Spray TBC Applied on Gas Turbine Components  
Omar Ligabue, Turbocoating S.p.A. omarligabue@turbocoating.it Francesco Bozza, Turbocoating S.p.A. Simone Bursich, Turbocoating S.p.A. Nelso Antolotti, Turbocoating S.p.A.
TBC V – June 24-29, 2018 Kloster Irsee,  Irsee, Germany,
ITSC 2018  – Orlando

Suspension Sprayed YSZ Thermal Barrier Coatings: on the Road to Industrial Application
Dr. Maria Barbosa1,2, Dr. Omar Ligabue3, Mr. Nick Kulissa1, Mr. Simone Bursich3, Dr. Filofteia-Laura Toma1, Dr. Denise Beitelschmidt1, and Mr. Luca Tagliaferri4; 1Fraunhofer Institute IWS, Dresden, Germany; 2Institute of Materials Science, Technische Universitat Dresden, Dresden, Germany, 3Turbocoating S.p.A., Rubbiano di Solignano (PR), Italy, 4Turbocoating Corp., Hickory, NC
ITSC 2018  – Orlando

Suspension Plasma Spray And Performance Characterization Of New Thermal Barrier Coatings
Mr. Nelso Antolotti , Turbocoating S.p.A., Rubbiano di Solignano (PR), Italy
Mr. Enea Ghidini , Turbocoating S.p.A., Rubbiano di Solignano (PR), Italy
Dr. Omar Ligabue , Turbocoating S.p.A., Rubbiano di Solignano (PR), Italy
Mr. Luca Tagliaferri , Turbocoating Corp., Hickory, NC
Mr. Simone Bursich , Turbocoating S.p.A., Rubbiano di Solignano (PR), Italy
Dr. Francesco Bozza , Turbocoating S.p.A., Rubbiano di Solignano (PR), Italy
ITSC 2018  – Orlando

Suspension plasma spray with ethanol and water based suspensions
F. Bozza, N. Antolotti, L. Tagliaferri, S. Bursich, E. Ghidini, O. Ligabue* Turbocoating S.p.a., Italy
ITSC 2017 – Dusseldorf

Improved sprayability on thermal spray coatings with different powder feeders
F. Bozza* Turbocoating S.p.a., Italy, N. Antolotti, L. Tagliaferri, S. Bursich, E. Ghidini, L. Coppelletti
ITSC 2017 – Dusseldorf

Atmospheric plasma-sprayed coatings for SOFCs
F. Bozza* Turbocoating S.p.a., Italy, N. Antolotti, L. Tagliaferri, M. Thoma, E. Ghidini
ITSC 2017 – Dusseldorf

Suspension plasma spraying of industrial gas turbine parts
N. Antolotti, F. Bozza, E. Ghidini, L. Tagliaferri, M. Thoma
ITSC 2016, SHANGHAI

Thermally sprayed coatings for Ultrasupercritical steam power plants
Nelso Antolotti, Francesco Bozza, Enea Ghidini, Luca Tagliaferri,
Turbocoating S.p.a. Martin Thoma (Consultant)
ITSC 2016, SHANGHAI

Protective coatings for SOFCs deposited using plasma spray techniques 
N. Antolotti, F. Bozza, E. Ghidini, L. Tagliaferri, M. Thoma
ITSC 2016, SHANGHAI

Thermally Sprayed Coatings For Supercritical Steam Power Plants: High Temperature And Fireside Corrosion Behavior
Mr. Nelso Antolotti1 , Dr. Francesco Bozza2 , Mr. Enea Ghidini2 , Mr. Luca Tagliaferri2 and Dr. Martin Thoma3 , 1 Turbocoating S.p.a., Rubbiano di Solignano (PR), Italy, 2 R & D, Turbocoating S.p.a., Rubbiano di Solignano (PR), Italy, 3 Consultant, Munich, Germany
ITSC 2015 – Long Beach – California

M-CrAlY Bond Coats For Single And Double Layer TBCs Applied By LPPS Or HVOF
Mr. Nelso Antolotti1 , Dr. Francesco Bozza2 , Mr. Enea Ghidini2 , Mr. Luca Tagliaferri2 and Dr. Martin Thoma3 , 1 Turbocoating S.p.a., Rubbiano di Solignano (PR), Italy, 2 R & D, Turbocoating S.p.a., Rubbiano di Solignano (PR), Italy, 3 Consultant, Munich, Germany
ITSC 2015 – Long Beach – California

Diffusion mechanisms and microstructure development in pack aluminizing of Ni-based alloys
Francesco Bozza, Giovanni Bolelli, Carlo Giolli, Andrea Giorgetti, Luca Lusvarghi, Paolo Sassatelli, Andrea Scrivani, Alessia Candeli, Martin Thoma

Surface and Coatings Technology 239(147) (2014)

Analisi del processo di “pack chromising” su superleghe di Ni per turbine a gas
F. Bozza, G. Bolelli, L. Lusvarghi, C. Siligardi, C. Giolli, A. Giorgetti, A. Scrivani

La Metallurgia Italiana – n. 3/2013

  • The efficient management of public R&D funding in order to promote the development of the territory
    S. Meneghetti, C. Giolli, A. Giorgetti, A. Scrivani
    Proceedings of Turbine Forum 2011, Nizza, 4-6 May 2011
  • Surface treatments for rework of new defective IGT components
    C. Giolli, A. Giorgetti, A. Scrivani, P. Ryan, C. Kunz, B. Allegrini, M. Thoma
    Proceedings of Turbine Forum 2011, Nizza, 4-6 May 2011
  • Non-destructive Technique for TBC life time assessment: Raman and Impedance SpectroscopIes
    C. Giolli, A. Giorgetti, A. Scrivani, F. Cernuschi, C. Rinaldi, A. Fossati, M. Di Ferdinando
    Proceedings of Turbine Forum 2011, Nizza, 4-6 May 2011

  • Improvement of the isothermal Oxidation Resistance of CoNiCrAlY coatings sprayed by High Velocity Oxygen Fuel
    A. Fossati, M. Di Ferdinando, A. Lavacchi, U. Bardi, C. Giolli, A. Scrivani
    Surface & Coatings Technology 204 (2010) 3723 – 3728
  • EFFETTO DELLA FINITURA SUPERFICIALE SUL COMPORTAMENTO AD OSSIDAZIONE STATICA DI BOND COAT A BASE MCrAlY REALIZZATI MEDIANTE TECNICA VPS
    M. Di Ferdinando, A. Fossati, U. Bardi, A. Lavacchi, A C. Giolli,. A. Scrivani
    Proceedings of AIM2010, Brescia, November 2010
  • L’UTILIZZO DEI FONDI PUBBLICI PER PROMUOVERE RICERCA E INNOVAZIONE IL CASO DI UN THERMAL SPRAY SHOP
    S. Meneghetti, C. Giolli, A. Giorgetti, A. Scrivani
    Proceedings of AIM2010, Brescia, November 2010
  • The management of  national and EC public funds for promoting innovation and R&D: the case of a thermal spray shop
    S. Meneghetti, C. Giolli, A. Giorgetti and A. Scrivani
    Proceedings of S2TS, Tours, October 2010
  • Effect of Ca addition in CoNiCrAlY powders for high temperature oxidation resistance HVOF coatings
    C. Giolli, A. Giorgetti, A. Scrivani, U. Bardi, A. Fossati, M. Di Ferdinando, G. Bolelli, F. Bozza
    Proceedings of Turbine Forum 2010, Nizza, 22-24 September 2010
  • Diffusion coatings for IGT aluminising techniques and the latest results from pack and CVD
    C. Giolli, A. Giorgetti, A. Scrivani, G. Borzone, C Costa, G. Bolelli, F. Bozza, M. Thoma
    Proceedings of Turbine Forum 2010, Nizza, 22-24 September 2010
  • TBC dry ice stripping
    C. Giolli, B. Allegrini, T. Duda, L. Engl, A. Giorgetti, A. Groppetti, A. Lanzi, S. Pini, M. Spagnoli and A. Scrivani
    Proceedings of ITSC2010, Singapore, May 3-5, 2010

  • Improvements in MCrAlY and TBC Stripping Processes
    C. Giolli, A. Giogetti, A. Scrivani, L. Engl, T. Duda
    Proceedings of Turbine Forum 2009, Nizza, 23- 25 April 2009
  • Recent activities in the field of thermal barrier coatings including burner rig testing in the European union
    Robert Vaßen, Federico Cernuschi, Gabriele Rizzi, Andrea Scrivani, Nicolaie Markocsan, Lars Östergren, Arjen Kloosterman, Remy Mevrel, Jörg Feist, John Nicholls
    Advanced Engineering Materials, Volume 10 Issue 10, Pages 907 – 921

  • Sviluppo e studio di nuovi rivestimenti ceramico compositi impiegabili ini sistemi abradibili
    U. Bardi, C. Giolli, A. Scrivani, G. Rizzi, F. Borgioli, A. Fossati, K. Partes, T. Seefeld D. Sporer and A. Refke
    Atti del Convegno Nazionale AIM, 24-26 settembre 2008
  • Comportamento ad alta temperatura di rivestimenti NiCrAlY prodotti mediante tecnica LASER cladding
    C. Giolli, K. Partes, F. Borgioli, A. Scrivani, G. Rizzi, T. Seefeld, F. Vollertsen
    Atti del Convegno Nazionale AIM, 24-26 settembre 2008
  • eXclean: a new surface preparation of turbine components for deposition of MCrAlY coatings with completely clean interface
    D. Russo, A. Scrivani, G. Rizzi, A. Lanzi, C. Giolli
    Proceedings of GT 2008, ASME Turbo Expo 2008: Power for Land, Sea and Air, June 9-13, 2008, Berlin, Germany
  • Development, characterization and testing of MCrAlY HVOF coating used as Bond coat for YPSZ Top Coat, Proceedings of GT 2008
    A. Scrivani, A. Lanzi, C. Giolli, G. Rizzi, D. Russo, M. Spagnoli
    ASME Turbo Expo 2008: Power for Land, Sea and Air, June 9-13, 2008, Berlin, Germany
  • Microstructure and wear resistance of plasma-sprayed carbides and ceramic coatings deposited on an Invar® alloy surface
    M. Turbil, C. Giolli, G. Rizzi, M. Rosso and A. Scrivani
    Proceedings of ITSC2008, Maastricht, June 2-4, 2008
  • Contamination free interface for thermal spray deposition of MCrAlY coatings through a new surface preparation named eXclean
    D. Russo, A. Scrivani, G. Rizzi, A. Lanzi, C. Giolli
    Proceedings of ITSC2008, Maastricht, June 2-4, 2008
  • Enhanced HVOF process for MCrAlY bond coat deposition
    A. Scrivani, C. Giolli, A. Lanzi, G. Rizzi, D. Russo, M. Spagnoli
    Proceedings of Turbine Forum 2008, Nizza, 23-25 April 2008
  • Tecniche metallografiche ed analitiche per il controllo dei rivestimenti spessi nel settore energetico
    A Scrivani, G Rizzi, C. Giolli
    Giornata di studio “Caratterizzazione fisica e funzionale dei rivestimenti”, Milano 26 febbraio 2008

  • An industrial R&D case: the development of thick and porous TBC
    C. Giolli, A. Scrivani, G. Rizzi
    Ed. N. Antolotti, C.C. Berndt, G. Rizzi, A. Scrivani, Turbocoating S.p.A., Parma, 2007, pp. 418 – 439
  • Stripping of thermal spary coatings from gas turbine components
    A. Scrivani, G. Rizzi
    Ed. N. Antolotti, C.C. Berndt, G. Rizzi, A. Scrivani, Turbocoating S.p.A., Parma, 2007, pp. 162 – 179
  • Surface treatments for stationary gas turbine components
    A. Scrivani, G. Rizzi
    Ed. N. Antolotti, C.C. Berndt, G. Rizzi, A. Scrivani, Turbocoating S.p.A., Parma, 2007, pp. 128 – 161
  • Aluminising Coating technologies for gas turbine applications
    A. Scrivani, G. Rizzi
    Guidelines for coating technology and characterization, Ed. N. Antolotti, C.C. Berndt, G. Rizzi, A. Scrivani, Turbocoating S.p.A., Parma, 2007, pp. 104-127
  • Thermal Barrier Coatings
    A Scrivani, G Rizzi
    The Basics, International Thermal Spray and Surface Engineering, Volume 2, Issue 4, November 2007
  • Characterization of TiO2 coatings prepared by a modified Electric Arc-Physical Vapor Deposition System
    C. Giolli, F. Borgioli, A. Credi, A. Di Fabio, A. Fossati, M. Muniz Minanda, S. Parmeggiani, G. Rizzi, A. Scrivani, S. Troglio, A. Tolstoguzov,  A. Zoppi, U. Bardi
    Surface Coatings and Technology, 202 (2007), 13–22
  • ENHANCED PLASMA SPRAYED THERMAL BARRIER COATING FOR GAS TURBINES COMBUSTION BASKETS AND TRANSITION PIECES
    A. Scrivani, G. Rizzi, A. Lanzi, M. Scartazza
    Abstract book of Thermal Barrier Coating II, Irsee, Germany, August 12-17, 2007
  • DEVELOPMENT OF THICK THERMAL BARRIER COATINGS WITH IMPROVED RESISTANCE TO THERMAL CYCLING FATIGUE
    A. Scrivani, G. Rizzi
    Abstract book of Thermal Barrier Coating II, Irsee, Germany, August 12-17, 2007
  • Photocatalytic behviour of TiO2 coatings prepared by a modified ElectricArc-Physical Vapour Deposition system
    C. Giolli, U. Bardi, F. Borgioli, A. Credi, M. Di Ferdinando, A. Fossati, S. Parmegiani, A. Di Fabio, G. Rizzi, A. Scrivani, S. Troglio
    Abstract Book of VI Convegno Nazionale sulla Scienza e Tecnologia dei Materiali, Perugia, 12-15 Giugno 2007
  • Thermal fatigue behaviour of thick and porous Thermal Barrier Coatings Systems
    A. Scrivani, G. Rizzi, U. Bardi, C. Giolli, M. Muniz Mirando, S. Ciattini, A. Fossati, F. Borgioli
    Proceedings of ITSC2007, Beijing, China, May 14 – 16, 2007, pp. 440-445