Anelastic Behavior of Plasma‐Sprayed Zirconia Coatings

Liu, Huan; Nakamura, Tsuneyoshi; Dwivedi, Gopal; Valarezo, Alfredo; Sampath, Sanjay

doi:10.1111/j.1551-2916.2008.02789.x

Cited by 64 publications

(48 citation statements)

References 23 publications

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“…For each case, coatings of 400(±15) lm thickness were obtained. After deposition, the specimens were placed on ex situ coating property (ECP) sensor (Ref [21][22][23][24], and were subjected to low temperature heat cycles, room temperature to~250°C. This characterization technique provides two mechanical properties of coatings; elastic modulus (E) and non-linear degree (ND) ( Ref 23,24).…”

Section: Experimental Methodsmentioning

confidence: 99%

Process-Property Relationship for Air Plasma-Sprayed Gadolinium Zirconate Coatings

et al. 2014

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The continuous need of elevating operating temperature of gas turbine engines has introduced several challenges with the current state-of-the-art yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBCs), requiring examination of new TBC material with high temperature phase stability, lower thermal conductivity, and resistance to environmental ash particles. Gadolinium zirconate (Gd 2 Zr 2 O 7 ) (GDZ) has been shown to meet many of these requirements, and has, in fact, been successfully implemented in to engine components. However, several fundamental issues related to the process-ability, toughness, and microstructural differences for GDZ when compared to equivalent YSZ coating. This study seeks to critically address the process-structure-property correlations for plasmasprayed GDZ coating subjected to controlled parametric exploration. Use of in-flight diagnostics coupled with in situ and ex situ coating property monitoring allows examination and comparison of the process-property interplay and the resultant differences between the two TBC compositions. The results indicate that it is feasible to retain material chemistry and fabricate relevant microstructures of interest with GDZ with concomitant performance advantages such as low conductivity, mechanical compliance, sintering resistance, and suppression of environmentally induced damage from ash particles. This study provides a framework for optimal design and manufacturing of emergent multi-layer and multi-material TBCs.

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Section: Experimental Methodsmentioning

confidence: 99%

Process-Property Relationship for Air Plasma-Sprayed Gadolinium Zirconate Coatings

et al. 2014

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“…The reason behind this nonlinear and hysteresis behavior has been discussed in detail in earlier studies (Ref 26,28). The behavior at the beginning of cooling highly depends on the maximum temperature during heating (Ref 28).…”

Section: Nonlinear Properties Extraction From Curvature-temperature Dmentioning

confidence: 95%

“…Figure 11 provides the map of nonlinear elastic properties of all the samples from batches 1, 2, and 3. Elastic modulus, the x-axis of the figure, is estimated from the linear region of the nonlinear stress-strain calculations, while degree of nonlinearity is calculated from the ratio of modulii between the linear portion of low-and high-strain regions (Ref 26,28). Effectively, the elastic modulus captures the extent of defects in the system (e.g., pores and interfaces) while the nonlinearity to a first approximation describes the nature of the interaction among the material surfaces within these pores and interfaces.…”

Section: Coatings Repeatability: Multiple Coatings For Single Processmentioning

confidence: 99%

“…Recently, a novel approach to quantify the nonlinear and anelastic properties of the coatings through recourse to substrate curvature measurements is developed (Ref 26). Through this approach, in addition to a simplified measure of elastic modulus (E), an additional parameter, namely, degree of nonlinearity (ND) in the stress-strain curve was used to quantify the microstructure along with linkage to processing conditions (Ref 27,28).…”

Section: Integrated Assessment Of Plasma Spray Tbc Reliability: From mentioning

confidence: 99%

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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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“…With this technique it is possible to produce free standing stripes with thicknesses in the range of 0.6 to several mm [4,7,52,53] that are suitable for 3-or 4-point bending experiments. The Young's modulus of thermally sprayed materials shows typically non-linear behavior [13,33,[54][55][56].…”

Section: Introductionmentioning

confidence: 99%