OPTIMIZATION OF THE PLASMA SPRAY PARAMETERS OF NiCrAlCoYO COATINGS USED LIKE BOND COAT IN THERMAL BARRIERS SYSTEMS

MCrAlY type coatings are used as coat bond between the ceramic layer and substrate type systems thermal barriers coatings. Among methods of manufacturing technology is thermal sprayed by atmospheric plasma, whose coatings are characterized as granular, rough, high porosity. The mechanical strength and thermal barriers protective function depends largely on the projection parameters, so they must be accurately controlled. This paper evaluates the influence of variables, electric current and voltage of the plasma torch in order to obtain the best answer on the microhardness and porosity of the coatings obtained by thermal spraying metal NiCoCrAlYO air plasma. Microstructural evaluation was performed by light microscopy with image analysis and scanning electron microscopy, likewise Vickers hardness measurements. The result shows that are possible to obtain dense coatings with higher hardness value than the specification, using a combination of 800 A of current and 40 V of torch plasma voltage.