scholarly journals Increase in Oxidation Resistance of MAR M-509 via LA-CVD Aluminizing

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1306
Author(s):  
Wojciech J. Nowak ◽  
Bernadeta Hader ◽  
Kamil Ochał ◽  
Bartek Wierzba
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Kinetics ◽  
Degradation Mechanism ◽  
Chemical Vapor ◽  
Optical Emission ◽  
Emission Spectrometry ◽  
Breakaway Oxidation ◽  
Temperature Application ◽  
Aluminide Layer ◽  
Low Activity

Due to their excellent mechanical properties, Co-based alloys are one of the main candidates to replace Ni-based alloys in high temperature application. Knowledge about oxidation resistance of Co-based alloy MAR M-509 and the extent of its aluminizing on its oxidation resistance is limited. Therefore, in the present study, an aluminide layer was manufactured by low activity chemical vapor deposition (LA-CVD) on MAR M-509. Aluminized and uncoated alloys were investigated in terms of oxidation kinetics and oxidation resistance during isothermal and cyclic oxidation at 1000 and 1100 °C. Material in the as-cast and after exposure was analyzed using scanning electron microscopy (SEM), thermogravimetry (TG) and glow-discharge optical emission spectrometry (GD-OES). Obtained results allowed for elucidating of degradation mechanism including nitridation process of carbides for MAR M-509. It was found that aluminizing of MAR M-509 significantly decreases its oxidation kinetics by the factor of 2.5 and 1.5 at 1000 and 1100 °C respectively. Moreover, the suppression of identified degradation mechanism in case of aluminized alloy was found until occurrence of breakaway oxidation of the aluminide layer. It was also proposed that further increase in oxidation resistance can be successively achieved by an increase in aluminide layer thickness.

scholarly journals Improved Pt Aluminide Coatings Using CVD and Novel Platinum Electroplating

1998 ◽  
Author(s):  
Bruce Michael Warnes
Keyword(s):  
Oxidation Resistance ◽  
Computer Control ◽  
Chemical Vapor ◽  
Plating Bath ◽  
Coating Technology ◽  
Diffusion Coatings ◽  
Aluminide Coatings ◽  
Coating Chamber ◽  
Low Activity ◽  
Platinum Electroplating

Chemical vapor deposition (CVD) is an old coating technology, but it was not successfully utilized to aluminize gas turbine hardware until recently (1989). In CVD aluminizing, the use of multiple, independently controlled, low temperature, external, metal halide generators combined with computer control of all process variables gives flexibility and consistent quality that is not possible with any other aluminizing process. It has been shown that harmful coating impurities (such as sulfur and boron etc.) can be transported to a coating from a high temperature aluminum source in the coating chamber during aluminizing. Representative processes include: pack cementation, above the pack, SNECMA, and high activity CVD. In contrast, it has also been demonstrated that CVD low activity aluminizing removes harmful impurities (S, P, B & W etc.) from the coating during deposition. Furthermore, clean, low activity coatings (simple aluminide MDC-210 or platinum modified MDC-150L) have been shown to exhibit superior oxidation resistance compared to similar coatings made by other aluminizing processes. A second significant source of impurities in platinum modified aluminide diffusion coatings is electroplating, that is, plating bath components (S, P, CI, K, Ca etc.) are codeposited with the platinum, and these impurities can have either a beneficial (K&Ca) or a detrimental (S,P&Cl) influence upon the oxidation resistance of the product coating. The results of investigations on the transport of impurities during aluminizing and electroplating, plus the influence of these impurities on oxidation resistance of the product coatings will be presented and discussed.

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