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Fabrication of Riblet Structures on a Ni‐based Superalloy (PWA1483) for Potential Drag Reduction in High Temperature Applications Based on Laser Optimization
Author(s) -
Schlieter Antje,
Shakhverdova I.,
Leyens C.
Publication year - 2015
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201400365
Subject(s) - materials science , fabrication , non blocking i/o , superalloy , oxide , composite material , bending , ultimate tensile strength , layer (electronics) , laser , stress (linguistics) , tension (geology) , metallurgy , microstructure , optics , medicine , biochemistry , chemistry , alternative medicine , physics , linguistics , philosophy , pathology , catalysis
We propose a new laser‐based fabrication process of small‐sized riblets on PWA1483 coated on a 3 μm‐thin sputtered Ni/Cr/Ni multilayer. Laser ablation was used for local material removal. Subsequent oxidation was used to provide an optimal riblet dimensions for a drug reduction and oxidation resistance. As a result of the heat treatment, a 7 μm oxide film was formed. The oxide film consists of two different oxide layers: while the upper one is formed of a dense Cr 2 O 3 layer with NiO, Cr 2 NiO 4 , and TiO 2 inclusions, the bottom one mainly consists of alpha‐Al 2 O 3 . Between the riblets, a TiO 2 layer was formed on the top of Cr 2 O 3 layer. First mechanical tests showed a promising riblet stability under the low‐cycle fatigue load, under tension, and under quasi‐cyclic bending load. The riblets also exhibit no severe failure by applying a quasi‐cyclic bending stress of 900 MPa for 200 times. Furthermore, cyclic tensile loading with a mean load of 500 MPa and an amplitude of 220 MPa corresponding to a strain range of 0.35% (stress level of R = 0.35) led to no damage of the riblet structure.