Temperature dependent mechanical properties of metallic HVOF coatings

Fiedler, Torben; Sinning, H.‐R.; Rösler, Joachim; Bäker, Martin

doi:10.1016/j.surfcoat.2018.05.062

Cited by 10 publications

(5 citation statements)

References 24 publications

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“…Since manufacturing of such samples is difficult, a method has been developed in the past where the geometry of irregularly shaped samples is determined using computer tomography and modeled in FEM simulations. This combination of vibrating reed and FEM was successfully implemented for thermally sprayed metallic and ceramic coatings, where a good agreement with mechanical tests was found [26,27]. Validation with monocrystalline silicon revealed a maximum difference of the measured Young's modulus of 0.4 % using the described procedure compared to literature values [26].…”

Section: Introductionmentioning

confidence: 72%

Temperature-Dependent Young’s Modulus of TaC- and TiC-Strengthened Co-Re-Based Alloys

Fiedler,

Seif,

Sinning

et al. 2024

Metals

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The knowledge of Young’s modulus is important for a quantitative assessment of strengthening contributions in CoRe alloys, such as strengthening by carbides. In this work, the temperature-dependent Young‘s modulus of monocarbide-strengthened CoRe-based alloys is measured using the vibrating reed technique. In this method, a reed-shaped sample is excited electrostatically, and the eigenfrequencies are determined. Using these frequencies, Young’s modulus can be derived analytically or, more reliably, assisted by finite element simulations. The resulting values for Young’s modulus are compared to theoretical estimations, and the influence of titanium- and tantalum-carbides on Young’s modulus is evaluated. It was found that low amounts of carbides increase Young’s modulus significantly. Analytical estimations are in good agreement with experimental results of TaC-containing alloys, whereas estimations for TiC-containing alloys are inaccurate.

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Section: Introductionmentioning

confidence: 72%

Temperature-Dependent Young’s Modulus of TaC- and TiC-Strengthened Co-Re-Based Alloys

Fiedler,

Seif,

Sinning

et al. 2024

Metals

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“…At room temperature, the critical elastic strain at which vertical cracks occur is about 0.55% [10]. At higher temperatures, higher critical strains can be expected as the coatings become increasingly ductile with increasing temperature [18].…”

Section: Introductionmentioning

confidence: 99%

“…For these simulations, material parameters for the coating system were determined. For this purpose, aluminium substrates were coated and removed in dilute NaOH solution to get free standing coatings [18]. These free standing coatings were investigated e.g.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Integrity of Thermal Barrier Coatings: Coating Development and Micromechanics

Fiedler

Rösler

Bäker

et al. 2020

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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To protect the copper liners of liquid-fuel rocket combustion chambers, a thermal barrier coating can be applied. Previously, a new metallic coating system was developed, consisting of a NiCuCrAl bond-coat and a Rene 80 top-coat, applied with high velocity oxyfuel spray (HVOF). The coatings are tested in laser cycling experiments to develop a detailed failure model, and critical loads for coating failure were defined. In this work, a coating system is designed for a generic engine to demonstrate the benefits of TBCs in rocket engines, and the mechanical loads and possible coating failure are analysed. Finally, the coatings are tested in a hypersonic wind tunnel with surface temperatures of 1350 K and above, where no coating failure was observed. Furthermore, cyclic experiments with a subscale combustion chamber were carried out. With a diffusion heat treatment, no large-scale coating delamination was observed, but the coating cracked vertically due to large cooling-induced stresses. These cracks are inevitable in rocket engines due to the very large thermal-strain differences between hot coating and cooled substrate. It is supposed that the cracks can be tolerated in rocket-engine application.

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“…It is known that the tribological performance of the coatings is influenced by their mechanical properties, microstructure and phase transformations induced during heat treatments [14,15]. The influence of temperature on the coatings’ properties is a current research issue [16] because in some applications such as machining the operating temperature can be significantly high. Nevertheless, it has been proven that a proper heat treatment can be useful to modify the microstructure of WC–Co coatings by reducing the porosity and promoting the formation of self-lubricant phases such as WO 3 and CoWO 4 [12,17].…”

Section: Introductionmentioning

confidence: 99%

Effect of heat treatment on the wet abrasion resistance of WC-10Co4Cr coatings deposited onto stainless steel by HVOF

Gallego

Chávez

Toro³

2021

Tribology - Materials, Surfaces & Interfaces

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In the present work, the relationship between the cavitation resistance of WC-Co based coatings and the thermal spraying parameters of the HVOF process was studied. The coatings were manufactured using DJH-2600 gun, which works with hydrogen and oxygen as combustion gases. The spraying process was automatized. Three repetitions were obtained for each projection condition to verify the experiments' repeatability. The resistance to cavitation was evaluated by the indirect test of the ASTM G-32 standard. The roughness of the coatings, its surface morphology and microstructure were studied with the aid of contact profilometer, SEM and optical microscopy. The porosity of the coatings was measured by digital image processing and the analysis of the phases present in the coating was carried out by XRD. Subsequently, the data obtained were correlated with the projection parameters to find the best spraying recipe. It was found that the total combustion flux was the parameter that had the strongest effect on every evaluated property, while the combustion ratio (RC) did not have a statistically significant effect on the levels evaluated in the experimental plan. It was possible to improve the cavitation resistance of the WC-Co based coatings using high levels of FTC and a combustion ratio close to the stoichiometric point.

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Temperature dependent mechanical properties of metallic HVOF coatings

Cited by 10 publications

References 24 publications

Temperature-Dependent Young’s Modulus of TaC- and TiC-Strengthened Co-Re-Based Alloys

Temperature-Dependent Young’s Modulus of TaC- and TiC-Strengthened Co-Re-Based Alloys

Mechanical Integrity of Thermal Barrier Coatings: Coating Development and Micromechanics

Effect of heat treatment on the wet abrasion resistance of WC-10Co4Cr coatings deposited onto stainless steel by HVOF

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