In situ measurement of residual stresses and elastic moduli in thermal sprayed coatings

Matějíček, Jiří; Sampath, Sanjay; Gilmore, Delwyn L.; Neiser, R.A.

doi:10.1016/s1359-6454(02)00477-9

Cited by 137 publications

(55 citation statements)

References 19 publications

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“…It has been found that transverse cracking/spallation substantially took place at these weak lamellar interfaces motivated by the great stress during cooling of the splats such as cubic yttria-stabilized zirconia (ZrO 2 -8 mol% Y 2 O 3 , 8YSZ) [34,35], lanthanum zirconia (LZ) [34,35], and titania (TiO 2 ) [36,37]. This seems to be well consistent with the low residual stress [38,39] and large crack spacing (relative to splat thickness) in thermally sprayed coatings. However, all materials forementioned such as LZ and TiO 2 are typical brittle ceramic materials with low fracture toughness.…”

Section: Introductionsupporting

confidence: 61%

Epitaxial growth and cracking of highly tough 7YSZ splats by thermal spray technology

Chen

Yang

2017

J Adv Ceram

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Thermally sprayed coatings are essentially layered materials and contain large numbers of lamellar pores. It is thus quite necessary to clarify the formation mechanism of lamellar pores which significantly influence coating performances. In the present study, to elaborate the formation mechanism of lamellar pores, the yttria-stabilized zirconia (ZrO 2 -7 wt% Y 2 O 3 , 7YSZ) splats, which have high fracture toughness and tetragonal phase stability, were employed. Interestingly, anomalous epitaxial growth occurred for all deposition temperatures in spite of the extremely high cooling rate, which clearly indicated chemical bonding and complete contact at splat/substrate interface before splat cooling. However, transverse spallation substantially occurred for all deposition temperatures in spite of the high fracture toughness of 7YSZ, which revealed that the lamellar pores were from transverse cracking/spallation due to the large stress during splat cooling. Additionally, fracture mechanics analysis was carried out, and it was found that the stress arose from the constraint effect of the shrinkage of the splat by locally heated substrate with the value about 1.97 GPa. This clearly demonstrated that the stress was indeed large enough to drive transverse cracking/spallation forming lamellar pores during splat cooling. All of these contribute to understanding the essential features of lamellar bonding and further tailoring the coating structures and performance.

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Section: Introductionsupporting

confidence: 61%

Epitaxial growth and cracking of highly tough 7YSZ splats by thermal spray technology

Chen

Yang

2017

J Adv Ceram

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“…In recent years, the use of in situ beam curvature measurements during deposition is prevalent in advanced laboratories and being adopted in manufacturing, which provides a first-hand account of coating formation dynamics through extraction of layer-by-layer stress evolution, as well as elastic properties of the deposited coating. [4][5][6][7] All of these sensors have allowed for greater insight into the processing-property-performance correlation, by allowing coating specialists to understand the various interplays between the hardware and feedstock selection to what the final coating properties and expected performance are. Such a methodology, termed process mapping, [8][9][10] has been a useful tool for rapid optimization of desired coating properties and enables the design for damage-tolerant coatings in a systematic fashion as opposed to a brute force, bottom-up optimization.…”

Section: Opportunitymentioning

confidence: 99%

Structurally Integrated, Damage-Tolerant, Thermal Spray Coatings

Vackel

Dwivedi

Sampath

2015

JOM

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Thermal spray coatings are used extensively for the protection and life extension of engineering components exposed to harsh wear and/or corrosion during service in aerospace, energy, and heavy machinery sectors. Cermet coatings applied via high-velocity thermal spray are used in aggressive wear situations almost always coupled with corrosive environments. In several instances (e.g., landing gear), coatings are considered as part of the structure requiring system-level considerations. Despite their widespread use, the technology has lacked generalized scientific principles for robust coating design, manufacturing, and performance analysis. Advances in process and in situ diagnostics have provided significant insights into the process-structure-property-performance correlations providing a framework-enhanced design. In this overview, critical aspects of materials, process, parametrics, and performance are discussed through exemplary studies on relevant compositions. The underlying connective theme is understanding and controlling residual stresses generation, which not only addresses process dynamics but also provides linkage for process-property relationship for both the system (e.g., fatigue) and the surface (wear and corrosion). The anisotropic microstructure also invokes the need for damage-tolerant material design to meet future goals.

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“…In-flight particle diagnostics was performed using DPV2000 sensor before each deposition. Coatings were deposited on the ICP sensor, which allows simultaneous measurement of substrate curvature and substrate temperature (Ref 35,36). This approach allows extraction of deposit stress evolution during deposition as well as elastic properties of the coating.…”

Section: Coatingsmentioning

confidence: 99%

Assessing Process and Coating Reliability Through Monitoring of Process and Design Relevant Coating Properties

et al. 2010

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Thermal spray in general, plasma spray in particular, is a highly complex process with numerous interacting variables associated with generation of the spray stream, deposit formation dynamics, and the resultant property linkages. Compounding this variability further are both the spatial (different booths and different locations) and temporal (process start-stops, hardware degradation, operator etc.) effects. As such, an understanding of process and coating consistency and variability offers significant challenges. Recent scientific advances as well as measurement tools have enabled elucidation of the intrinsic variabilities associated with each of the process sub-steps; however, integrated understanding of the system level reliability is still lacking. This article seeks an integrated assessment of process and coating reliability through systematic measurements of variabilities during each stage of the process subjected to different operating parameters. Through critical examination of first-order process maps, the influence of process parameters on particle state is reviewed for repeated spray runs with a single parameter effect as well as across a spectrum of process parameters. In addition, influence of these changes on designrelevant coating properties were obtained for plasma-sprayed zirconia through recourse to novel in situ and ex situ substrate curvature measurements. Finally, the implications of such integrated reliability studies have been explored through collaborative experiments conducted in the industrial sites.

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In situ measurement of residual stresses and elastic moduli in thermal sprayed coatings

Cited by 137 publications

References 19 publications

Epitaxial growth and cracking of highly tough 7YSZ splats by thermal spray technology

Epitaxial growth and cracking of highly tough 7YSZ splats by thermal spray technology

Structurally Integrated, Damage-Tolerant, Thermal Spray Coatings

Assessing Process and Coating Reliability Through Monitoring of Process and Design Relevant Coating Properties

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