Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Microstructural Changes in Suspension Plasma-Sprayed TBCs Deposited on Complex Geometry Substrates
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-6619-8799
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-9578-4076
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-4201-668x
2020 (English)In: Coatings, E-ISSN 2079-6412, Vol. 10, no 7, article id 699Article in journal (Refereed) Published
Abstract [en]

Thermal barrier coatings (TBCs) are considered a promising solution for improving the efficiency of internal combustion engines. Among the thermal spray processes, the relatively newly developed suspension plasma spray (SPS) is an attractive candidate due to its unique microstructural features that have already demonstrated increased performance in gas turbine applications. To achieve these features, thermal spray conditions play an essential role. In specific uses, such as piston of diesel engines, parameters as spray angle and spray distance pose challenges to keep them constant during the whole spray process due to the complex geometry of the piston. To understand the effect of the spray distance and spray angle, a comprehensive investigation of the produced thermal spray microstructure on the piston geometry was conducted. Flat and complex geometry surfaces were coated using the same plasma parameters while the spray angle and distance were changed. Characterization was performed using scanning electron microscopy (SEM) combined with the image analysis technique to perceive the variation of the thickness and microstructures features such as pores, cracks, column density, and column orientation. The results showed that the changes in spray angles and spray distances due to the complex shape of the substrate have a significant influence on the microstructure and thermal properties (thermal conductivity and thermal effusivity) of the coatings. The thermal conductivity and thermal effusivity were calculated by modeling for the different regions of the piston and measured by laser flash analysis combined with modeling for the flat-surfaced coupon. It was shown that the modeling approach is an effective tool to predict the thermal properties and thus to understand the influence of the parameters on the coating properties. Connecting the observations of the work on the microstructural and thermal properties, the complex geometry’s influence on the produced coatings could be diminished by tailoring the process and generating the most desirable TBC for the internal combustion engines in future applications.

Place, publisher, year, edition, pages
MDPI, 2020. Vol. 10, no 7, article id 699
Keywords [en]
complex geometry substrate, internal combustion engines, object-oriented finite element (OOF2), suspension plasma spraying, thermal barrier coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
URN: urn:nbn:se:hv:diva-15726DOI: 10.3390/coatings10070699ISI: 000554806700001Scopus ID: 2-s2.0-85088257159OAI: oai:DiVA.org:hv-15726DiVA, id: diva2:1460362
Funder
Swedish Energy AgencyAvailable from: 2020-08-24 Created: 2020-08-24 Last updated: 2022-05-11
In thesis
1. Thermal barrier coatings for diesel engines
Open this publication in new window or tab >>Thermal barrier coatings for diesel engines
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Termiska barriärbeläggningar för dieselmotorer
Abstract [en]

The upward trend in internal combustion engine efficiency is driven by the demands for emission reduction and fossil fuel depletion. No present alternative fuel can produce energy comparable to that produced by conventional oil; this necessitates the reasonable, efficient usage of oil. For several decades, thermal barrier coatings (TBCs) have been studied as an answer for increasing the thermal efficiency of gas turbine engines. However, TBCs have not been extensively evaluated for application to internal combustion engines owing to their emissions, costs, and demanding working conditions. Much effort is needed to simultaneously address this problem and expand the applicability of thermal barrier coatings.The objective of this study is to investigate the relationships between the spraying parameters, microstructural variations, thermal properties, and performance of TBCs applied to diesel engines. The further objective is to harness this knowledgeto fabricate coatings that result in high automotive engine efficiencies. Different feedstock materials were used with various spraying methods and classified into separate TBC types. The first TBC type had a lamellar bond coat deposited by atmospheric plasma spray (APS) and lamellar yttria-stabilized zirconia (YSZ) APS top coat. The second TBC type was derived from the first TBC type and had a lamellar APS bond coat, and the top coat was deposited by APS using a feedstock along with a porosity former, resulting in high-porosity top coats. The third TBC type had a dense bond coat deposited with high velocity air fuel (HVAF) and a columnar top coat deposited by suspension plasma spray (SPS) using a feedstock of YSZ or gadolinium zirconate (GZO). The SPS technique can generate a variety of microstructures, and the TBCs containing these microstructures were tested in an internal combustion engine for the first time. The fourth TBC type had a dense bond coat deposited HVAF, a columnar top coat produced with SPS and an additional top layer, which functioned as the sealing layer.

For the thermophysical property investigation of all coating types, experimental and modeling techniques—laser flash analysis (LFA) and object-oriented finite element (OOF) analysis, respectively—were employed. To evaluate the optical properties of the coatings, two methods were adopted, namely, spectral normal hemispherical reflectivity at room temperature (SNHRRT) and spectral normal emissivity at high temperature (SNEHT). The functional performance of the coatings was evaluated on the basis of the TBC behavior under cyclic thermal loads; thermal cyclic furnace test, flame rig test, thermal swing test, and a single cylinder engine experiment were conducted. The coatings were characterized by scanning electron microscopy (SEM) before and after the functional performance test. The coating performance was correlated to the microstructural, thermophysical, and optical properties of the coatings.

The results of this study infer that the TBC type significantly influences the thermal properties and thermal cyclic performance, which can be correlated with the porosity levels and the pore types. The complex substrate geometry of the piston resulted in inherent variations in spray angle and spray distance, leading to different coating microstructures and porosities owing to the changes in the particle trajectory and in-flight characteristics. Further, the single-cylinder engine evaluation demonstrated that the high-emissivity second TBC type or the third TBC type with a porous microstructure and a low thermal effusivity resulted in a high engine efficiency.

Abstract [sv]

En ökad effektivitet i förbränningen hos dieselmotorer krävs för att kunna uppfylla de allt högre kraven på minskad miljöpåverkan och ett minskat användande av fossila bränslen. Inget alternativt bränsle finns idag som kan producera energi som är jämförbar med den som produceras av konventionell olja, vilket förutsätter en effektiv användning av olja. Under flera decennier har termiska barriärbeläggningar (TBC) varit en lösning för att öka den termiska effektiviteten hos gasturbinmotorer. Beläggningarna har dock inte utvärderats i tillräcklig omfattning för dieselmotorer. Forskning är av detta skäl nödvändig för att skapa förutsättningar för att denna typ av beläggningar kommersiellt skall kunna tillämpas i dieselmotorer.

Syftet med detta arbete är att utforska sambandet mellan processparametrar, beläggningsmikrostruktur, termiska egenskaper och prestanda hos termiska barriärbeläggningar för dieselmotorer. Målet med arbetet är att skapa beläggningar som resulterar i hög förbränningsverkningsgrad. Olika beläggningsmaterial utvärderades och kategoriserades med olika spruttekniker. Det första materialet som utvärderades var yttriumoxidstabiliserad zirkoniumdioxid (YSZ) som sprutades med atmosfärisk plasmassprutning (APS). Denna beläggning användes som referensprov. Det andra materialet var en vidareutveckling av den första beläggningen där porositet i beläggningen skapades med hjälp av ett tillsatsmaterial, vilket resulterade i beläggningar med hög porositet. Den tredje typen var en så kallad kolumnär mikrosstrukturbeläggning som skapades med suspensionsplasmasprutning (SPS) och tillsatsmaterialet YSZ. SPS tekniken valdes även för gadoliniumstabiliserad zirkoniumdioxid. Anledningen till att tekniken SPS utvärderades var att denna teknik i gasturbinapplikationer visat sig kapabel till att producera ett stort antal olika typer av mikrostrukturer. Den fjärde typen av beläggning som utvärderades var ett SPS producerat beläggningssystem där ytterligare ett så kallat toppskikt som tätskikt sprutades.

Prestanda och egenskaper utvärderades för samtliga skapade beläggningar genom såväl experimentella tekniker som modellering där laser flash analysis (LFA) och finita elementanalys är exempel. För att utvärdera beläggningarnas optiska egenskaper användes två metoder, spektral normal hemisfärisk reflektivitet vid rumstemperatur (SNHRRT) och spektral normal emissivitet vid hög temperatur (SNEHT). Beläggningarnas livslängd utvärderades indirekt med hjälp av termisk utmattning i ugn, termisk utmattning med förbränningslåga och med ett motorexperiment. Beläggningarnas mikrostruktur analyserades genom svepelektronmikroskopi (SEM) före och efter prestandautvärderingarna. Beläggningsprestanda korrelerades därefter till beläggningarnas mikrostruktur, termiska och optiska egenskaper samt de funktionella egenskaperna.

Resultaten av studien visar att valet av TBC-typ signifikant påverkar de termiska egenskaperna och de termiska utmattningsegenskaperna, och att dessa skillnader kan korreleras med porositetsnivåerna och portyperna i beläggningarnas mikrostruktur. Motorkolvens komplexa substratgeometri orsakade variationer i sprutvinkel och sprutavstånd, vilket ledde till olika beläggningsmikrostrukturer på kolvens olika ytor. Motorutvärderingen visade att den andra TBC-typen med hög emissivitet och den tredje TBC-typen med en porös mikrostruktur och en låg termisk effusivitet resulterade i hög motoreffektivitet.

Place, publisher, year, edition, pages
Trollhättan: University West, 2022. p. 107
Series
PhD Thesis: University West ; 49
Keywords
Thermal Barrier Coatings; Suspension Plasma Spraying; Gadolinium Zirconate; Internal Combustion Engines; Engine Efficiency, Termiska barriärbeläggningar; Plasmasprutning; Suspensionssprutning; Gadolinium; Zirkoniumdioxid; Förbränningsmotorer; Motoreffektivitet
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-18369 (URN)978-91-89325-23-4 (ISBN)978-91-89325-22-7 (ISBN)
Public defence
2022-06-17, F131, Gustava Melins gata, Trollhättan, 10:00 (English)
Opponent
Supervisors
Note

Delarbeten är endast i tryckt form tillgängliga och finns inte med i den elektroniska versionen.

Available from: 2022-05-25 Created: 2022-05-11 Last updated: 2022-06-21Bibliographically approved

Open Access in DiVA

fulltext(7002 kB)102 downloads
File information
File name FULLTEXT01.pdfFile size 7002 kBChecksum SHA-512
b3d81a1cd8a9807ac1277392985c531ab90d104c512dda3c8b1447dbdcf3936970e5bfae60f8ae61fc06f688cdf7b70dbe1202c2995699723be3e7b3936c7170
Type fulltextMimetype application/pdf

Other links

Publisher's full textScopus

Authority records

Uczak de Goes, WellingtonMarkocsan, NicolaieGupta, Mohit Kumar

Search in DiVA

By author/editor
Uczak de Goes, WellingtonMarkocsan, NicolaieGupta, Mohit Kumar
By organisation
Division of Subtractive and Additive Manufacturing
Manufacturing, Surface and Joining Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 102 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 151 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf