"Development of Cold Spray CoNiCrAlY coating process on turbine blades airfoils for oxidation protection"
High pressure cold spray (CS) methods are possible to apply this class of coatings, offering a number of advantages such as: (i) lower deposition temperature, leading to no oxidation of the powder ; (ii) possibility of obtaining very dense coating layers; (iii) high deposition efficiency; (iv) lower transverse speed of the torch, making it easier to follow complex geometries.
In this paper, we present a study on the properties of CS CoNiCrAlY for protection from high temperature oxidation and show how CS technology can apply such coatings on one specific airfoil geometry. CoNiCrAlY coatings were applied on GTD111 base metal and samples were submitted to isothermal high temperature oxidation testing for comparison with HVOF sprayed samples. The responses of the coating to post-coating treatments were also investigated. Using spray parameters selected through the oxidation tests, the process was transferred to a mock-up turbine airfoil.
Properties such as coating thickness uniformity, deposition efficiency, interface quality, and coating quality in critical spots like leading and trailing edge, fillet radii and shroud surface have been analyzed.