Damage mechanisms of metallic HVOF-coatings for high heat flux application
| Autor: | Torben Fiedler, Joachim Rösler, Martin Bäker, Roland Groß |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Kirkendall effect Delamination Alloy Metallurgy chemistry.chemical_element 02 engineering and technology Surfaces and Interfaces General Chemistry engineering.material 021001 nanoscience & nanotechnology Condensed Matter Physics Copper Surfaces Coatings and Films Liquid fuel 020303 mechanical engineering & transports 0203 mechanical engineering chemistry Materials Chemistry engineering 0210 nano-technology Porosity Thermal spraying Liquid hydrogen |
| Zdroj: | Surface and Coatings Technology. 316:219-225 |
| ISSN: | 0257-8972 |
| DOI: | 10.1016/j.surfcoat.2017.03.037 |
| Popis: | The copper wall of regeneratively cooled liquid fuel rocket-combustion chambers is exposed to high thermomechanical loads. Although it is cooled by liquid hydrogen in internal cooling channels, surface temperatures of more than 800 °C on the hot-gas side are reached. To lower this temperature and to protect the copper against oxidation, a metallic coating system is developed. It is applied with high velocity oxygen fuel spray (HVOF) and consists of a bond coat and a top coat. As top-coat materials, two candidates were tested in this study: A nickel-based and a cobalt-rhenium-based alloy. For the bond-coat, a new NiCuCrAl alloy has been developed previously. The purpose of this article is to investigate the failure mechanisms of the new metallic coating systems. For this purpose, two tests are applied. On the one hand, laser-cycling experiments are conducted to test the coatings with a thermal gradient between top-surface and substrate and to investigate the influence of high heating rates. On the other hand, the coatings were tested isothermally in a furnace to investigate the coatings without any thermal gradient. Interface delamination, buckling, formation of vertical cracks and kirkendall porosity are identified as relevant failure mechanisms and the conditions under which they will occur are discussed. |
| Databáze: | OpenAIRE |
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