First Stages of Oxidation of Pt-Modified Nickel Aluminide Bond Coat Systems at Low Oxygen Partial Pressure

• Published in: Oxidation of metals Vol. 78; no. 5-6; pp. 269 - 284
• Main Authors: Alvarado-Orozco, J. M., Morales-Estrella, R., Boldrick, M. S., Ortiz-Merino, J. L., Konitzer, D. G., Trápaga-Martínez, G., Muñoz-Saldaña, J.
• Format: Journal Article
• Language: English
• Published: New York Springer-Verlag 01.12.2012; Springer
• Subjects: Applied sciences; Chemistry and Materials Science; Corrosion; Corrosion and Coatings; Corrosion environments; Exact sciences and technology; Inorganic Chemistry; Materials Science; Metallic Materials; Metals. Metallurgy; Nonmetallic coatings; Original Paper; Production techniques; Surface treatment; Tribology; Platinum aluminide; Oxidation kinetics; TBC systems; TGO; Alumina; Nickel base alloys; Intermetallic compound; Aluminium alloy; Non metal coating; Thermal barrier; Surface treatment; Partial pressure; Corrosion; Low pressure; Nickel Aluminides; Oxidation; Kinetics
• ISSN: 0030-770X; 1573-4889
• DOI: 10.1007/s11085-012-9305-7

The θ-Al 2 O 3  → α-Al 2 O 3 phase transformation was investigated in thermally grown oxide formed on β-(Ni,Pt)Al bond coats during isothermal exposures at 900–1,200 °C in an argon atmosphere stream with the O 2 partial pressure of 1 × 10 −5  atm. Local curve fitting was used to evaluate the evolution of the parabolic rate constant, k p , using a general kinetic model ( t  =  A  +  B Δ m  +  C Δ m 2 ), during the first 5 h of oxidation. All net mass–gain curves exhibited deviations from the classic parabolic model, Δ m  =  k p t ½ ; a steady state regime was established only after 4 h of exposures, except for the sample oxidized at 1,100 °C.