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- Battabyal, Manjusha, 1979, et al.
(författare)
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Comparison of microstructure in Ni-Al single splats and millimeter sized drops
- 2011
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Ingår i: Surface Modification Technologies XXV. - 9788191057140 ; , s. 3-12
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Konferensbidrag (refereegranskat)abstract
- Splat studies are a central area of research because they can provide fundamental knowledge on the phenomena controlling the final coating properties such as coating microstructure and adhesion. Wetting and heat transfer are expected to influence the final splat shape while they are in turn controlled by the presence of oxides and adsorbed species on the substrate surface. It is however difficult to follow the flattening of a sprayed droplet at the micrometer scale. Since the mid nineties, so-called free falling experiments have been developed with which it is possible to simulate the thermal spray process. The millimetre sized drops allow investigating the flattening and solidification occurring in milliseconds instead of in microseconds.In this study, the microstructure of plasma sprayed Ni-Al splats and millimetre sized droplets produced on TiAlV and pure Ti substrates, respectively, are compared. By use of scanning electron microscopy (SEM), especially the cross-section of splats and droplets has been investigated. In the splats, diffusion across the splat-substrate interface and the formation of an interface layer is detected. In the droplets, up to 3 different layers are formed at the interface to the substrate. The microstructure at the interface and the phases present are discussed and their influence on heat transfer and coating properties are described.In this study, the microstructure of plasma sprayed Ni-Al splats and millimetre sized droplets produced on TiAlV and pure Ti substrates, respectively, are compared. By use of scanning electron microscopy (SEM), especially the cross-section of splats and droplets has been investigated. In the splats, diffusion across the splat-substrate interface and the formation of an interface layer is detected. In the droplets, up to 3 different layers are formed at the interface to the substrate. The microstructure at the interface and the phases present are discussed and their influence on heat transfer and coating properties are described.
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- Gupta, Mohit Kumar, et al.
(författare)
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Structure-property Relationships in Thermal Barrier Coatings by Finite Element Modelling
- 2012
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Ingår i: Surface Modification Technologies XXV : proceedings of the Twenty Fifth International Conference on Surface Modification Technologies. - [Chennai] : Valardocs. - 9788191057140 ; , s. 175-184
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Konferensbidrag (refereegranskat)abstract
- The thermal and mechanical properties of Thermal Barrier Coating systems (TBCs) are strongly influenced by coating defects, such as delaminations and pores, thus making it essential to have a fundamental understanding of microstructure-property relationships in TBCs, to produce a desired coating. Object-Oriented Finite element analysis (OOF) has been shown previously as an effective tool for evaluating thermal and mechanical material behaviour, as this method is capable of incorporating the inherent material microstructure as an input to the model. In this work, OOF was used to predict the thermal conductivity and effective Young’s modulus of TBC topcoats. A Design of Experiments (DoE) was conducted by varying selected spray parameters for spraying Yttria Partially Stabilized Zirconia (YPSZ) topcoat. Characterisation of the coatings included microstructure, porosity and crack content and thermal conductivity measurements. The relationships between microstructural features, thermal conductivity and Young’s modulus are discussed.
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