Degradation of EB-PVD thermal barrier coatings caused by CMAS deposits

Residual Stresses of Eb-pvd Thermal Barrier Coatings Exposed to High Temperature

The substrate material was nickel-based superalloy (In738LC), and CoNiCrAlY was pressureless plasma-sprayed on the substrate as the bond coating. As the top coating, zirconia with 4 mol% yttria was electron beam-physical vapor deposited (EB-PVD) on the rotating substrate. The rotation speeds in the EB-PVD process were 5, 10 and 20rpm. The specimens were exposed to 1273K in air atmosphere for 20...

Erosion, Corrosion and Erosion-Corrosion of EB PVD Thermal Barrier Coatings

Electron beam (EB) physical vapour deposited (PVD) thermal barrier coatings (TBCs) have been used in gas turbine engines for a number of years. The primary mode of failure is attributed to oxidation of the bondcoat and growth of the thermally grown oxide (TGO), the alumina scale that forms on the bondcoat and to which the ceramic top coat adheres. Once the TGO reaches a critical thickness the T...

Calcium-Magnesium-Aluminosilicate (CMAS) Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings

The thermochemical reactions between calcium-magnesium-aluminosilicate(CMAS-) based road sand and several advanced turbine engine environmnetal barrier coating (EBC) materials were studied. The phase stability, reaction kinetics and degradation mechanisms of rare earth (RE)-silicates Yb2SiO5, Y2Si2O7, and RE-oxide doped HfO2 and ZrO2 under the CMAS infiltration condition at 1500 C were investi...

CMAS Corrosion of EB PVD TBCs: Identifying the Minimum Level to Initiate Damage

Properties of PVD hard coatings

Last 2 to 3 decades application of PVD (physical vapour deposition) hard coatings exponentially grows. However, the use of hard, thin films in the field of machine elements is the exception rather than the rule. The main problem lies in the relatively high contact pressure and the very complex loading of machine components, which demand a hard resistance surface and a tough core. In seminar it ...