title: Degradation of nonmodified and rhodium modified aluminide coating deposited on CMSX 4 superalloy.
abstract: The Ni-base superalloy CMSX 4 used in the turbine blades of aircraft engines was coated with rhodium layer (0.5-μm thick). Next coated CMSX 4 superalloy was aluminized by the CVD method. The rhodium modified aluminide coating and nonmodified aluminide coating were oxidized at 1100°C at the air atmosphere. The rhodium modified aluminide coating showed about twice better oxidation resistance than the nonmodified one. The spallation equal 62% of the total area was observed on the surface of the nonmodified coating whereas only 36% spallation area was observed on the surface of the rhodium modified aluminide coating after the oxidation test. The oxide layer formed on the surface of the nonmodified coating was composed of nonprotective (Ni,Cr)Al2 O4 and (Ni,Cr)O phases. Aluminium in the coating reacts with oxygen, forming a protective α-Al2 O3 oxide on the surface of the rhodium modified aluminide coating. When the oxide cracks and spalls due to oxidation, additional aluminium from the coating diffuses to the surface to form the oxide. The presence of protective Al2 O3 oxide on the surface of the rhodium modified aluminide coating slows coating degradation. Therefore, rhodium modified aluminide coating has better oxidation resistance than the nonmodified one.
authors.affiliation: Department of Materials Science, Rzeszow University of Technology, Rzeszow, Poland.
authors.forename: Maryana
authors.initials: M
authors.lastname: Zagula-Yavorska
authors.affiliation: Department of Materials Science, Rzeszow University of Technology, Rzeszow, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Wierzbińska
authors.affiliation: Department of Materials Science, Rzeszow University of Technology, Rzeszow, Poland.
authors.forename: Kamil
authors.initials: K
authors.lastname: Gancarczyk
authors.affiliation: Department of Materials Science, Rzeszow University of Technology, Rzeszow, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Sieniawski
keywords: CMSX 4 superalloy; degradation; oxidation test; rhodium