Advances in Thermal Barrier Coatings (TBC) for High Temperature Gas Turbines

EasyChair Preprint 10341

Abstract

Increasing the turbine inlet temperature, turbine blades face high temperature hot corrosion (850℃ to 950℃ ) that limits the life of the turbine blade. During hot corrosion, molten sodium salts and vanadium oxide condense over the surface of turbine blades, consume protective oxide layers and diffuse into the microstructure of super alloy. As a result, fatigue and creep phenomena are accelerated leading to fracture. In this paper the use of hot corrosion resistant coating i.e. thermal barrier coatings has been investigated. Over the past few years it has proven to be an effective strategy to avoid premature failure. Hot corrosion reaction in conventional coatings transforms tetragonal zirconia to monoclinic phase and form large crystalline products which induces thermal stress and cracking upon cooling. While, nanostructured, rare earth elements co-doped and multiple layered thermal barrier coatings possess superior hot corrosion resistance than these conventional coatings. Also, high porosity in nanostructured, low reactivity of rare earth elements and diffusion hindrance of multilayered coatings resist hot corrosion processes. In conventional metallic bond coatings, hot corrosion destroys protective oxide layers and consumes aluminium and chromium contents. When reinforced with nanoparticles, rare earth elements and gradient aluminium layers, metallic bond coatings improve their hot corrosion resistance. These modifications develop continuous protective alumina and chromium oxide layer, prohibit diffusion of molten salts and increase aluminium content of bond coatings. Evaluation of coatings using XRD techniques, SEM spectroscopy and corrosion kinetics curves exhibit superiority of hot corrosion resistant coatings over conventional coatings.

Keyphrases: Fatigue life, High temperature hot corrosion, Thermal barrier coatings, creep rate, gradient coatings, low temperature hot corrosion, nanostructured coatings, rare earth elements

@booklet{EasyChair:10341,
  author    = {Zahid Mehmood and Ali Sarosh and Osama Ali Ahmed Awan},
  title     = {Advances in Thermal Barrier Coatings (TBC) for High Temperature Gas Turbines},
  howpublished = {EasyChair Preprint 10341},
  year      = {EasyChair, 2023}}