ISSN 2594-5327
51º Congresso anual — Vol. 51 , num. 1 (1996)
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A single sputtered NiCrAlY coating and a complex coating of inner ion plating TiN and outer sputtered NiCrAlY have been prepared on the Ti₃Al-Nb intermetallic compound. Their oxidation behavior has been studied at 900°C in air by thermogravimetry combined with XRD, SEM and EDX. It is shown that Ti₃Al-Nb suffers from rapid oxidation, forming a mixed scale containing an outer thin Al₂O₃ rich layer and inner thick TiO₂ rich layer doped with Nb. The weight gain of the single sputtered NiCrAlY is smaller than that of Ti₃Al-Nb during oxidation for less than 30 hours and then becomes larger, which may be due to the rapid outward diffusion of Ti and the formation of TiO₂. The intermediate TiN layer can greatly improve the oxidation performance of NiCrAlY coating and inhibit outward diffusion of Ti and inward diffusion of Ni, Cr, etc. Its oxidation is divided into three stages: from initial very slow oxidation to rapid oxidation and then to stable oxidation. The initial weight gain mainly results from the formation of Al₂O₃; The outward diffusion of Ti in the substrate and formation of TiO₂ are responsible for the second rapid oxidation stage. Then, the oxidation gets into the third stage, stably forming TiO₂ and Al₂O₃.
A single sputtered NiCrAlY coating and a complex coating of inner ion plating TiN and outer sputtered NiCrAlY have been prepared on the Ti₃Al-Nb intermetallic compound. Their oxidation behavior has been studied at 900°C in air by thermogravimetry combined with XRD, SEM and EDX. It is shown that Ti₃Al-Nb suffers from rapid oxidation, forming a mixed scale containing an outer thin Al₂O₃ rich layer and inner thick TiO₂ rich layer doped with Nb. The weight gain of the single sputtered NiCrAlY is smaller than that of Ti₃Al-Nb during oxidation for less than 30 hours and then becomes larger, which may be due to the rapid outward diffusion of Ti and the formation of TiO₂. The intermediate TiN layer can greatly improve the oxidation performance of NiCrAlY coating and inhibit outward diffusion of Ti and inward diffusion of Ni, Cr, etc. Its oxidation is divided into three stages: from initial very slow oxidation to rapid oxidation and then to stable oxidation. The initial weight gain mainly results from the formation of Al₂O₃; The outward diffusion of Ti in the substrate and formation of TiO₂ are responsible for the second rapid oxidation stage. Then, the oxidation gets into the third stage, stably forming TiO₂ and Al₂O₃.
Palavras-chave
Oxidation, Ti₃Al-Nb, Coatings, Sputtered NiCrAlY, Ion plating TiN
Oxidation, Ti₃Al-Nb, Coatings, Sputtered NiCrAlY, Ion plating TiN
Como citar
Assunção, Fernando C. Rizzo; Zeng, Chaoliu; Wu, Weitao.
EFFECT OF AN INTERMEDIATE TiN LAYER ON THE OXIDATION OF NiCrAlY COATED Ti₃Al-Nb AT 900°C,
p. 2284-2293.
In: 51º Congresso anual,
Porto Alegre, Brasil,
1996.
ISSN: 2594-5327, DOI 10.5151/2594-5327-51v3-713-722
