Thermal properties of plasma-sprayed functionally graded thermal barrier coatings

Khor, K.A.; Gu, Yang

doi:10.1016/s0040-6090(00)01024-5

Cited by 186 publications

(73 citation statements)

References 15 publications

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“…Very similar structures have been observed in experiments for Al 2 O 3 / Y-TZP FGMs ͑two-phase case͒ 8 and ZrO 2 / NiCoCrAlY FGMs ͑three-phase case͒. 45,46 Once the random phase distributions for the FGM layers are produced, we then use our LBM approach to solve the transport governing equations for the multiphase material systems. The predicted results are finally compared with the available experimental data for both two-phase and threephase cases.…”

Section: B Actual Functionally Graded Materialsmentioning

confidence: 55%

“…24 For ZrO 2 -only porous materials, big cracks have been reported due to the difficulty in remelting ZrO 2 powders during spraying. 45 As a result, the measured thermal conductivity is much lower than the predicted one. Otherwise, the present predictions are consistent with the experimental data.…”

Section: B Actual Functionally Graded Materialsmentioning

confidence: 87%

“…45. This ZrO 2 / NiCoCrAlY FGM is actually a three-phase system, for the porosity ͑air volume fraction͒ in the material increases with the fraction of ZrO 2 FIG.…”

Section: B Actual Functionally Graded Materialsmentioning

confidence: 94%

“…Figure 8 shows the predicted effective thermal conductivities of a ZrO 2 / NiCoCrAlY FGM compared with the experimental data measured by Khor and Gu. 45 Both the thermal conductivity and density used in our simulations are 3 W/m K and 6 g/cm 3 for pure ZrO 2 , and 5 W / m K and 7.324 g / cm 3 for pure NiCoCrAlY, respectively. The thermal conductivity of air is 0.025 W / m K in the simulations.…”

Section: B Actual Functionally Graded Materialsmentioning

confidence: 99%

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Transport properties of functionally graded materials

Wang¹,

Meng

Pan³

2007

Journal of Applied Physics

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This paper presents a numerical method to predict the effective transport properties of multiphase functionally graded materials, accounting for the effects of random phase distribution and multiphase interactions. Firstly, the multiphase microstructures of such graded materials are reproduced by a random generation-growth algorithm, and then the corresponding transport governing equations are solved using a high-efficiency lattice Boltzmann method. The predicted effective electric and thermal conductivities agree well with the existing experimental data for both two-and three-phase functionally graded materials. Furthermore when the methodology is extended to other transport and even nontransport physical properties of multiphase composites, our simulated results still agree much better with the available experimental data than the existing theoretical models. This may exhibit the robusticity and wider applicability of the present approach.

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Section: B Actual Functionally Graded Materialsmentioning

confidence: 55%

Section: B Actual Functionally Graded Materialsmentioning

confidence: 87%

“…45. This ZrO 2 / NiCoCrAlY FGM is actually a three-phase system, for the porosity ͑air volume fraction͒ in the material increases with the fraction of ZrO 2 FIG.…”

Section: B Actual Functionally Graded Materialsmentioning

confidence: 94%

Section: B Actual Functionally Graded Materialsmentioning

confidence: 99%

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Transport properties of functionally graded materials

Wang¹,

Meng

Pan³

2007

Journal of Applied Physics

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“…A gradual transition in properties through the coating thickness can be established [16,17] and will assist the reduction in residual stresses [18.19] associated with thermal expansion mismatch [20,21]. The external part of the specimens resistance to thermal shock cracking can be improved [22,23] as well as a superior bonding between compositions of material allowing for it to become more resistant to delamination [24,25]. It has been demonstrated that functionally graded heat resistant coatings also have better resistance to oxidization and a longer lifetime during test conditions than those formed without any type of functional grading [26].…”

Section: Fig1mentioning

confidence: 99%

Laser melting functionally graded composition of Waspaloy® and Zirconia powders

Mumtaz

Hopkinson

2007

J Mater Sci

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An approach for fabricating functionally graded specimens of supernickel alloy and ceramic compositions via Selective Laser Melting (SLM) is presented. The focus aimed at using the Functionally Graded Material (FGM) concept to gradually grade powdered compositions of Zirconia within a base material of Waspaloy ® . A high power Nd:YAG laser was used to process the material compositions to a high density with gradual but discrete changes between layered compositions. The graded specimens initially consisted of 100% Waspaloy ® with subsequent layers containing increased volume compositions of Zirconia (0-10%).Specimens were examined for porosity and microstructure. It was found that specimens contained an average porosity of 0.34% with a gradual change between layers without any major interface defects.

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Study of microstructure and thermal shock behavior of two types of thermal barrier coatings

Saeedi

Sabour

Khoddamı

2009

Materials & Corrosion

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Gas turbines provide one of the most severe environments challenging material systems nowadays. Only an appropriate coating system can supply protection particularly for turbine blades. This study was made by comparison of properties of two different types of thermal barrier coatings (TBCs) in order to improve the surface characteristics of high temperature components. These TBCs consisted of a duplex TBC and a five layered functionally graded TBC. In duplex TBCs, 0.35 mm thick yittria partially stabilized zirconia top coat (YSZ) was deposited by air plasma spraying and 0.15 mm thick NiCrAlY bond coat was deposited by high velocity oxyfuel spraying. 0.5 mm thick functionally graded TBC was sprayed by varying the feeding ratio of YSZ/NiCrAlY powders. Both coatings were deposited on IN 738LC alloy as a substrate. Microstructural characterization was performed by SEM and optical microscopy whereas phase analysis and chemical composition changes of the coatings and oxides formed during the tests were studied by XRD and EDX. The performance of the coatings fabricated with the optimum processing conditions was evaluated as a function of intense thermal cycling test at 1100 8C. During thermal shock test, FGM coating failed after 150 and duplex coating failed after 85 cycles. The adhesion strength of the coatings to the substrate was also measured. Finally, it is found that FGM coating has a larger lifetime than the duplex TBC, especially with regard to the adhesion strength of the coatings.

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Thermal properties of plasma-sprayed functionally graded thermal barrier coatings

Cited by 186 publications

References 15 publications

Transport properties of functionally graded materials

Transport properties of functionally graded materials

Laser melting functionally graded composition of Waspaloy® and Zirconia powders

Study of microstructure and thermal shock behavior of two types of thermal barrier coatings

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