Investigating the transition time reduction in evaporation of NiCrAlY using EB–PVD

Abstract

Thermal barrier coatings have been widely considered owing to increasing efficiency of gas turbine engines. These coatings are often available in ceramic, thermally grown oxide and metallic bond layers. The function of metallic bond layer in these coatings is adhesion improvement and substrate protection. This layer can also be applied for electron beam-physical vapour deposition (EB-PVD). Yet, EB-PVD method cannot control evaporation process to be able to induce a deposit with uniform chemical composition along the coating thickness. The present study investigates composition variation during evaporation process of Ni-20Cr-11Al-0?3Y alloy using computational models and experimental results along with transition time prediction by computational model. To this end, EB-PVD by an electron gun with power of 3 kW in 4-6610 25 mbar vacuums was used. The results indicated that applying an initial molten pool with a composition similar to that of equilibrium pool (Ni-2Cr-15Al-0?5Y) decreases transition time by 70%.

Effect of substrate temperature on the oxidation behaviour of NiCrAlY coating

“…Physical vapour deposition (PVD) is one of the techniques in the alloys deposition processes [3]. PVD techniques can be used to deposit MCrAlY coatings; these include electron beam (EB-PVD) [4,5], magnetron sputtering (MS) [6] and cathodic arc deposition (CAD) [7,8]. In the CAD process, the difference between the chemical composition of the target and the coating is negligible; therefore, the alloys can be easily deposited [9,10].…”

Investigating efficiency of α-Al2O3 diffusion barrier layer in oxidation of EB-PVD NiCrAlY coatings

“…[1][2][3][4][5][6][7] These coatings can be used as both overlay and bond coatings in thermal barrier coating systems. [8][9][10] Oxidation of these coatings in both cases is one of the most important reasons for reduction in their lifetime; thus, many studies have been focused on improving their oxidation resistance. 11 One of the most important factors in reducing oxidation resistance in these coatings when being exposed to high temperatures is interdiffusion between superalloy substrate and coating, which usually occurs at temperatures of more than 1000uC.…”