Stable crack propagation in free standing thermal sprayed Al2O3 and Al2O3ZrO2TiO2 coatings

Neumann, Marc; Gehre, Patrick; Kuebler, Jakob; Dadivanyan, Natalia; Jelitto, Hans; Schneider, Gerold A.; Aneziris, Christos G.

doi:10.1016/j.ceramint.2019.01.200

Cited by 18 publications

(4 citation statements)

References 45 publications

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“…Figure 7 shows the representative load‐displacement curves obtained during R‐curve measurements, corrected as done before in other works with the same device 30,43 . This procedure was adopted because due to the dead weight of the machine's upper support, the force did not start at zero.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 7 shows the representative load-displacement curves obtained during R-curve measurements, corrected as done before in other works with the same device. 30,43 The composites exhibit different behavior. The force increases until the crack starts to propagate, then it goes down similarly to monolithic references with a constant toughness regime.…”

Section: F I G U R Ementioning

confidence: 99%

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Microstructure and mechanical behavior of TiO₂‐MnO‐doped alumina/alumina laminates

et al. 2020

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Since Clegg et al 1 were successful in producing weak interfaces in laminated ceramic composites to obtain a noncatastrophic failure, several studies were done presenting ceramics with laminar structures as an effective alternative to overcome the typical brittleness of monolithic ceramics, to avoid catastrophic failure, to modify the crack path, and to increase fracture toughness. One approach widely used for ceramic laminates is to generate compressive residual stresses in layers due to different coefficients of thermal expansion (CTE), considering interfaces with strong adhesion. The idea is to achieve high levels of compressive stresses in these layers to control or oppose crack propagation, activating toughening mechanisms as crack arresting, crack bifurcation, and microcracking. Thus, it is possible for laminates to enhance fracture toughness and to absorb more energy during failure, compared to reference monolithic ceramics. 2-11. Another way to enhance toughness in laminates is to produce weak interfaces or layers to cause crack deflection. This behavior strongly depends on the fracture energy and Young's modulus of weak and strong layers of the composite. The volume fraction of pores and the pore interaction have an important contribution to ensure that crack continues

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Section: Resultsmentioning

confidence: 99%

Section: F I G U R Ementioning

confidence: 99%

Microstructure and mechanical behavior of TiO₂‐MnO‐doped alumina/alumina laminates

et al. 2020

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“…The fired filters were then coated by flame spraying with commercially available Pure Alumina Thermal Spray Flexicord (Saint‐Gobain, France) using a MasterJet flame spray gun (Saint‐Gobain, France). The exact spray process parameters are described by Neumann et al [ 29 ]…”

Section: Methodsmentioning

confidence: 99%

Rapid Prototyping of Carbon‐Bonded Alumina Filters with Flame‐Sprayed Alumina Coating for Bottom‐Teeming Steel Ingot Casting

Wetzig

Neumann

Schwarz³

et al. 2021

Adv Eng Mater

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Although continuous casting is the state‐of‐the‐art casting method in steelmaking, ingot casting by bottom teeming has kept its relevance, for example, in the area of specialty steels. The main challenge is to meet the ever‐increasing quality requirements demanded by the customers. Regarding high‐performance steel applications, the purity with respect to the content of nonmetallic inclusions thereby is of special interest. Herein, foam templates with tailored geometry are designed and manufactured by selective laser sintering. Different coating techniques based on carbon‐bonded alumina slurries are applied to replicate foam structures with miniature cube geometry and cylindrical geometry. The techniques are evaluated regarding the porosity, pore size distribution, bulk density, mechanical strength, and shrinkage of the resulting filters. Suitable processing routes are selected to manufacture prototype batches with near‐net‐shape geometry. Finally, the feasibility of applying a flame spray coating is tested. First samples of the prototype batch are tested in industrial bottom‐teeming ingot casting.

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“…Such free-standing coatings allow measurements of properties that are difficult or rather impossible to determine with a substrate underneath. These measurements can be mechanical tests, e.g., for the evaluation of Young's modulus [1], bending strength [2], creep [3,4] or sintering properties [5][6][7], toughness [8], and crack propagation [9,10]. Additionally, functional properties like thermal diffusivity [11], optical properties [12], phase evolution [13], and attack by corrosive species as Calcium-Magnesium-Aluminum-Silicate (CMAS, [14]) are measured on free-standing coatings.…”

Section: Introductionmentioning

confidence: 99%

Influence of Substrate Removal Method on the Properties of Free-Standing YSZ Coatings

2021

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Thermally sprayed ceramic coatings are often tested as free-standing layers to investigate different properties such as thermal expansion coefficient, thermal conductivity, sintering, mechanical behavior, corrosion resistance, gas tightness, or electrical properties. In this paper, four different substrate removal methods were used to obtain free-standing YSZ coatings. At first, spraying on a steel substrate and subsequent dissolution of the substrate-coating interface by hydrochloric acid (HCl) was used. Second, the steel substrate was removed by applying an electrical field via electrochemical corrosion of the surface of the substrate. In a third method, the coating was sprayed on a salt (NaCI) interlayer, which was removed later by dissolution in water. At last, the coating was sprayed on a graphite substrate and the substrate was removed by heat treatment. After the preparation of free-standing coatings, these were characterized using scanning electron microscopy, mercury porosimetry, indentation tests, and room temperature three-point bending tests, which allowed the determination of Young’s modulus and viscosity. The results revealed measurable differences in coating properties as a result of the substrate removal methods, i.e., HCl method led to higher porosity and lower modulus in the YSZ coating.

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Stable crack propagation in free standing thermal sprayed Al2O3 and Al2O3ZrO2TiO2 coatings

Cited by 18 publications

References 45 publications

Microstructure and mechanical behavior of TiO₂‐MnO‐doped alumina/alumina laminates

Microstructure and mechanical behavior of TiO₂‐MnO‐doped alumina/alumina laminates

Rapid Prototyping of Carbon‐Bonded Alumina Filters with Flame‐Sprayed Alumina Coating for Bottom‐Teeming Steel Ingot Casting

Influence of Substrate Removal Method on the Properties of Free-Standing YSZ Coatings

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Stable crack propagation in free standing thermal sprayed Al2O3 and Al2O3ZrO2TiO2 coatings

Cited by 18 publications

References 45 publications

Microstructure and mechanical behavior of TiO2‐MnO‐doped alumina/alumina laminates

Microstructure and mechanical behavior of TiO2‐MnO‐doped alumina/alumina laminates

Rapid Prototyping of Carbon‐Bonded Alumina Filters with Flame‐Sprayed Alumina Coating for Bottom‐Teeming Steel Ingot Casting

Influence of Substrate Removal Method on the Properties of Free-Standing YSZ Coatings

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Microstructure and mechanical behavior of TiO₂‐MnO‐doped alumina/alumina laminates

Microstructure and mechanical behavior of TiO₂‐MnO‐doped alumina/alumina laminates