|
7274 |
|
Wednesday, May 04, 2022, Hall G2 12:10 PM Arc Spraying |
|
Thermal barrier coatings based on arc spraying of amorphous Fe-based alloys and NiCrAlY for cryogenic applications |
|
Michél Hauer* / Fraunhofer Institute for Large Structures in Production Engineering IGP, Thermal Joining Engineering, Germany Benedikt Allebrodt / DURUM Verschleiss-Schutz GmbH, Germany Knuth-Michael Henkel/ Chair of Joining Technology, University of Rostock, Germany |
|
Thermally sprayed coatings or coating composites can serve as a key technology for the energy turnaround in various new industrial applications. For instance, currently, there is no experience in maritime production, offshore storage and transport of large quantities of liquid hydrogen (LH2) due to the developing market. Instead, current tank designs refer to standard designs onshore with thick walls and comparatively high thermal conductivity. This currently reduces cost effectiveness due to boil-off and disregards some other requirements such as high corrosion resistance, mechanical and cyclic strength. Therefore, thermal barrier coatings (TBC) applied by thermal spraying are becoming the focus of attention due to their high insulating effect and wear resistance to counteract boil-off and additionally protect the tank shell from dynamic sloshing forces. A key factor influencing the thermal conductivity is the porosity of such coatings. In the current work, a typical NiCrAlY alloy and, moreover, amorphous Fe-based alloys are arc-sprayed due to the combination of high cost efficiency, easy process handling and customizable coating properties. Previous own works for other applications and further literature revealed that coatings sprayed with nitrogen or a mixture of nitrogen and hydrogen show superior coating qualities with respect to oxidation and electrical conductivity. Thus, nitrogen is used as process gas, while the stand-off distance was varied to modify the porosity in a targeted manner. The results demonstrate coatings with low porosity and oxide content and high electrical conductivity. Especially the amorphous Fe-based coatings reveal homogeneous coating structures and properties. Further investigations regard the thermal conductivity, residual stresses, hardness and durability under cryogenic conditions. |