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| 2. |
- Fasth, Angelica, et al.
(författare)
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A comparative study of mechanical properties between HVOF-sprayed Maxphase materials
- 2009
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Ingår i: Proceedings of the 22nd International Conference on Surface Modification Techniques. - 9780981706511 ; , s. 149-156
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Konferensbidrag (refereegranskat)abstract
- Mn+1AXn –phases (MAX-phase materials) are ternary compounds consisting of an early transition metal (M), such as Ti or V, a p-element from group III-V (A) and C and/or N (X). The phases have a layered structure in which the A element form planes separated by MX slabs. This nanolaminated atomic arrangement gives rise to a unique set of properties. These properties in combination with a good match in thermal expansion between substrate and coating make MAX-phase materials challenging materials to extend the lifetime of thermal barrier coatings. Evaluation of properties of HVOF sprayed MAX-phase materials and to compare these properties with commercially used bond coat materials such as MCrAlY coatings is thus of great interest which was the aim of this study.The non-linear load displacement relationships and Young’s modulus for HVOF-sprayed Ti2AlC coatings and APSsprayed NiCoCrAlY coatings onto Hastalloy X substrates were determined using data from both Berkovich andspherical microindentation. Results between Berkovich and spherical microindentation measurements are comparedand discussed.
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| 5. |
- Klement, Uta, 1962, et al.
(författare)
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Characterization of single splats produced by plasma spraying
- 2009
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Ingår i: Proceedings of the 22nd International Conference on Surface Modification Technologies. - 9780981706511 ; , s. 31-37
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Konferensbidrag (refereegranskat)abstract
- When sprayed particles impinge on the substrate, they flatten, cool down and build-up – splat by splat – the laminar structure of the thermal spray coating. Splat studies are therefore 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. In the present study, Ni-5Al single splats on 2 different Ti-6Al-4V substrates (one pre-heated and the other maintained at room temperature prior to spraying) have been investigated. Splat morphology has been analyzed by use of scanning electron microscopy (SEM). Analytical techniques like energy dispersive X-ray spectrometry (EDS) and Auger electron spectrometry (AES) have been used to determine the composition of the splats and of the splat-substrate interface. Adhesion was found to determine the splat microstructure. Two microconstituents are observed in the microstructure when delamination occurs. In case of good contact between splat and substrate, the microstructure consists of single-phase solid solution and an additional layer was found at the splat-substrate interface. Site-specific focused ion beam (FIB) milling and transmission electron microscopy (TEM) has been used to investigate this layer in more detail.
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| 6. |
- Lyphout, Christophe, 1981-, et al.
(författare)
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Characterization of adhesion strenght of HVOF sprayed IN718 coatings
- 2009
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Ingår i: Proceedings of th 22nd Internationa Conference on Surface Modification technolgies - SMT22. Trollhättan, Sweden. - : VALAR Docs. - 9780981706511 ; , s. 11-18
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Konferensbidrag (refereegranskat)abstract
- The tensile adhesion strength of thermally sprayed coating is conventionally evaluated via the ASTM C633-69 standard. The maximum measurable adhesion is then limited by the adhesion strength of the polymer media. High velocity oxy-fuel (HVOF) spraying can exhibit very high bonding strength and thus it is essential to develop an alternative method to evaluate coating adhesion strength. In this work a Modified Tensile Adhesion Test (MTAT) is proposed replacing gluing with induction brazing. The method was evaluated for HVOF sprayed Inconel 718 coatings deposited on Inconel 718 substrates. The effect of induction brazing process and the characteristics of the braze-coating interface was given particular interest. The results indicate that the method is superior to the ASTM C633-69 for characterisation of adhesion of coatings with high bond strength.
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| 8. |
- Markocsan, Nicolaie, et al.
(författare)
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Effect of heat treatment on low conductive thermal barrier coatings
- 2009
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Ingår i: Proceedings of the 22nd International Conference on Surface Modification Technologies. - 9780981706511 ; , s. 139-147
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Konferensbidrag (refereegranskat)abstract
- Development of Thermal Barrier Coating (TBC) systems will allow higher combustion temperature which is of interest for all manufactures since it results in higher fuel efficiency and environmentally cleaner emissions. Low thermal conductivity and long service life are the most important properties of these coatings. The objective of the work presented in this paper was to study the influence of a long-term heat treatment (i.e. 1200°C/2000h) on different characteristics of atmospheric plasma sprayed TBCs. Two zirconia feedstock materials were evaluated, namely yttria partially stabilised zirconia and dysprosia partially stabilised zirconia. Several spray conditions were designed and employed in order to achieve different coating morphologies. Microstructure analyses revealed that the coating microstructure was significantly dependent on both operating conditions and heat treatment conditions. Significant changes in coatings porosity occurred during heat treatment. The lowest thermal conductivity was reached with the dysprosia partially stabilised zirconia material. All TBC systems experienced decomposition of the metastable t´ phase during long heat treatment at 1200°C.
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