Measurement of coatings' elastic properties by mechanical methods: Part 2. Application to thermal barrier coatings

Beghini, Marco; Benamati, G.; Bertini, Leonardo; Frendo, Francesco

doi:10.1007/bf02323923

Cited by 32 publications

(15 citation statements)

References 21 publications

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“…2) exhibits the elastic response of the sample to the external loading, and is governed by the elastic moduli of the coating and substrate. With the elastic modulus of the stainless steel substrate (200 GPa from a standard tensile test, not shown here), the modulus of the coating, E coating , can be calculated from the initial slope of the curve using composite plate theory [26][27][28][29] :…”

Section: Elastic Modulus Of the Coatingmentioning

confidence: 99%

Interfacial adhesion measurement of a ceramic coating on metal substrate

Nie

Zhou

et al. 2009

J Coat Technol Res

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The interfacial adhesion measurement of a ceramic coating on a metal substrate is studied by three-point bending (3PB) technique. In the measurement, interfacial cracks are induced during the 3PB test, and the interfacial energy release rate is calculated from the released energy per unit crack surface area during crack extension under the fixed displacement conditions. A finite element analysis (FEA) model encompassing the plastic behavior of the metal substrate is developed to simulate the 3PB test and extract the energy data. The inputs to the FEA model include the crack length, the maximum and critical loads corresponding to crack initiation, and the mechanical properties of the coating and substrate. A MoB/CoCr ceramic coating/stainless steel substrate system is investigated by the technique for demonstrating the utility of the technique.

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Section: Elastic Modulus Of the Coatingmentioning

confidence: 99%

Interfacial adhesion measurement of a ceramic coating on metal substrate

Nie

Zhou

et al. 2009

J Coat Technol Res

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“…305-311). 21 With regard to Poisson's ratio of the coating, accurate values of the strain ratio ~ and of substrate Poisson's ratio are required. The corresponding evaluated condition numbers for the assumed test specimen are about 5.5 and 4.6 (see Table 3), and layer thickness and Young's moduli have a much lower influence.…”

Section: I I I I I I I I I I I I I I I I I I Imentioning

confidence: 99%

Measurement of coatings' elastic properties by mechanical methods: Part 1. Consideration on experimental errors

Beghini

Bertini

Frendo

2001

Experimental Mechanics

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ABSTRACT--A critical analysis of some mechanical methods employed for measuring the elastic properties of coatings is presented. A rational basis for properly choosing test methods, transducers and layer thicknesses is provided. The analyzed methods, usually applied to relatively thick coatings, include four-point bending tests and the resonance technique. General relationships for the evaluation of coatings' elastic properties, derived from the multUayer beam and plate theories, are discussed. On the basis of the error propagation theory, for different combinations of materials and layer thicknesses, the influence of typical experimental errors, test setup parameters and material properties is analyzed, and sensitivity coefficients for relative errors are discussed. The critical experimental variables and their effect on measurement accuracy are highlighted, suggesting suitable conditions for selecting specimen geometry and testing conditions. A procedure for measurement at high temperature is outlined.KEY WORDS--Coatings, elastic modulus, sensitivity analysis, experimental errors Nomenclature X, Y, Z = Cartesian coordinate system ~X, E:y, ~Z = normal strains ~x, cry, cr z = normal stresses hk = thickness of the kth layer lk = z-coordinate of the kth layer's centroid Ik-1 = z-coordinate of the inferior surface of the kth layer lie = z-coordinate of the superior surface of the kth layer gk = depth coordinate of the kth layer centroid, with reference to the geometric center of the specimen B = specimen width H = total specimen thickness K}, = specimen bending stiffness in the Rx, Ry = radii of curvature of the specimen geometrical axis in the Z-X and Z-Y planes Cx, Cy = normal strains of the centroid fiber in the Z-X and Z-Y cross sections 8 = position, in the beam model, of the neutral axis related to the geometric centroid of the specimen L = total specimen length S = inner spacing between the loading pins in the FPB test a = spacing between the inner and outer loading pins in the FPB test P = half load, applied in the FPB test Es, Ec = elastic modulus of the substrate and coating materials hs, hc = thickness of the substrate and coating layers ~s, ec = measured longitudinal strain on the external coating surface and substrate surface w = midsection displacement, related to the fixed external loading pins k = distance of the measuring gage from the neutral axis of the specimen f = first bending resonance frequency of the specimen = 4.73004 m = mass of the specimen = ratio of the transverse to the longitudinal strain measured on the external specimen surface F = ratio of the longitudinal strains measured on the substrate and coating surfaces R = ratio of the substrate to the coating thickness cz = ratio of the coating to the substrate elastic modulus Pe,.c = slope of the experimental regression line correlating the measured load and strain on the substrate or coating surfaces Pw = slope of the experimental regression line correlating the measured load and midsection displacement = relationship giving the coating ...

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“…It is also known that the properties can be enhanced by the postspray treatment, the temperature of which is above approximately 1000°C (Ref [8][9][10]. However, the report of high-temperature mechanical properties is not sufficient (Ref 10,11), because evaluation of high-temperature mechanical properties of the coating is not so easy.…”

Section: Introductionmentioning

confidence: 95%

Effect of Thermal Treatment on High-Temperature Mechanical Properties Enhancement in LPPS, HVOF, and APS CoNiCrAlY Coatings

2009

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The mechanical properties of a MCrAlY coating significantly influence the initiation of cracks in the superalloy substrate under thermomechanical-fatigue conditions. Previous studies have developed a convenient method for evaluating the mechanical properties of sprayed coatings by lateral compression of a circular tube coating. This method does not need chucking, and manufacturing the free-standing coating is quite straightforward. In this study, the mechanical properties of the free-standing CoNiCrAlY coatings prepared using low-pressure plasma spraying (LPPS), high-velocity oxyfuel (HVOF) spraying, and atmospheric plasma spraying (APS) were systematically measured with the lateral compression method at room temperature through to 920°C. The effect of postspray thermal treatments, in vacuum and in air, on the mechanical properties was investigated in the 400 to 1100°C temperature range. It was found that high-temperature thermal treatment in air was effective in increasing the bending strength and YoungÕs modulus. It was especially effective on the APS coatings, which were produced using powders with average size 60 lm, and on HVOF coating, whose bending strengths increased by approximately three times. On the contrary, the enhancement in the LPPS and APS coatings produced with powders 21 lm in size was found to be approximately 1.6 times.

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Measurement of coatings' elastic properties by mechanical methods: Part 2. Application to thermal barrier coatings

Cited by 32 publications

References 21 publications

Interfacial adhesion measurement of a ceramic coating on metal substrate

Interfacial adhesion measurement of a ceramic coating on metal substrate

Measurement of coatings' elastic properties by mechanical methods: Part 1. Consideration on experimental errors

Effect of Thermal Treatment on High-Temperature Mechanical Properties Enhancement in LPPS, HVOF, and APS CoNiCrAlY Coatings

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