Protective coatings for aeronautic and power generation turbines components deposited by plasma spray

Coatings produced by aluminium diffusion, called aluminide are employed to increase the oxidation and corrosion resistance, increasing the life of Ni and Co base superalloys components at temperatures comprised between 900 an d 1050 degrees C. Consequently these coatings are frequently employed in ae ronautic and Fewer generation turbines as well as in the chemical industry. Aluminides are industrially produced by pack cementation or CVD and recent ly it has been demonstrated that its resistance significantly increases whe n Cr is added (chrome-aluminides). During this work, a feasibility study ha s been carried out in order to determine if plasma spray can be employed fo r depositing this type of coatings on turbine blades. Therefore, aluminium and aluminium/chromium layers were deposited on Ni base IN100 superalloy sp ecimens that were subsequently subjected to a diffusion heat treatment unde r Ar flow Characterisation and analysis of the coatings were carried out by metallography, SEM and EDS. Cyclic oxidation tests were carried out at 105 0 degrees C while molten sulphate hot corrosion was performed at 900 degree s C. The results of this preliminary study are promising and indicate that plasma spray can be developed as an industrial process for production of al uminide and chrome-aluminide coatings.