1 / 16

Project submitted for MASTER OF MECHANICAL ENGINEERING RPI East Hartford, CT Presented by

Dependence of Fracture Toughness of Ceramic Thermal Barrier Coatings on Microstructure: Electron Beam Physical Vapor Deposition vs. Air Plasma Spray. Project submitted for MASTER OF MECHANICAL ENGINEERING RPI East Hartford, CT Presented by Danh Tran 11/17/2014. Outlines. Objectives

angelica-rosales
Download Presentation

Project submitted for MASTER OF MECHANICAL ENGINEERING RPI East Hartford, CT Presented by

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dependence of Fracture Toughness of Ceramic Thermal Barrier Coatings on Microstructure:Electron Beam Physical Vapor Deposition vs. Air Plasma Spray Project submitted for MASTER OF MECHANICAL ENGINEERING RPI East Hartford, CT Presented by Danh Tran 11/17/2014

  2. Outlines • Objectives • Thermal Barrier Coatings Processes - Air Plasma Spray (APS) - Electron Beam Physical Vapor Deposition (EB-PVD) • Fracture Toughness Measurement using Vickers Nano-indentation method • Microstructure of samples - APS - EB-PVD • Results - Compare Fracture Toughness (KIC) of APS vs. EB-PVD

  3. Objectives • To Compare Fracture Toughness of ceramic layer deposited by different Thermal Barrier Coatings processes: • Air Plasma Spray (APS) vs. Electron Beam – Physical Vapor Deposition • To Observe crack characteristics of ceramic layer by both processes

  4. x Ceramic Bond Coat Substrate Active Introduction TBCs reduces metal temperature of gas turbine blades

  5. TBCs processes - Air Plasma Spray (APS) APS provides multi-layer ceramic with splat structure

  6. TBCs processes – Electron Beam Physical Vapor Deposition (EB-PVD) EB-PVD provides ceramic with columnar structure ± 30° • A simple EB-PVD process: • Under vacuum (10-4 to 10-5 torr) • Bending of the electron beam is obtained by a magnetic field perpendicular to the drawing.

  7. Vickers Test Diagram c Fracture Toughness (KIC) The fracture toughness KIC, is a measure of the material’s resistance to the propagation of a crack. where: KIC : Fracture Toughness (MPa-m1/2) K : empirical constant (no unit) E : Young’s Modulus (GPa) HV : Vickers Hardness (GPa) P : Load (N) c : crack length (m) K = 0.036 (Ref.)

  8. TBCs Microstructures • APS process provides multi-layer ceramic with splat structure • EB-PVD provides columnar structure EB-PVD Columnar microstructure APS microstructure

  9. Crack length & Fracture Toughness Experiment • Prepare two Thermal Barrier Coatings samples • One from APS process • One from EB-PVD process • Apply loads on samples at multiple locations (using Vickers Hardness Tester): – 25gf , 50gf, 100gf and 200gf (*) (*) NOTE: Applied load based on tester’s minimum load as starting point • Record Hardness data from applied loads • Measure & compare crack lengths under microscope between two processes

  10. c Vickers Test Diagram Crack length & Fracture Toughness Experiment (cont’) Ceramic from APS, cracks widely spread to surrounding area Measured crack’s length on APS samples: Load = 25gf Mag = 500X

  11. c Vickers Test Diagram Crack length & Fracture Toughness Experiment (cont’) Ceramic from EB-PVD, cracks propagate within grain boundary Measured crack’s length on APS samples: Load = 25gf Mag = 500X

  12. Results Average crack from APS is longer than EB-PVD at each applied load Reason: APS has lower fracture toughness

  13. Results (cont’) Average Vickers Hardness from APS is lower than EB-PVD’s

  14. Slope 314 Slope 111 Results (cont’) • Smaller slope requires bigger load to increase crack length • Ceramic from EB-PVD process is harder than APS’s

  15. Conclusions • For each applied load: - Vickers hardness of ceramic from APS is lower than EB-PVD - Average crack from APS is longer than EB-PVD’s • Ceramic from APS has lower KIC than EB-PVD’s • Empirical constant, K, which was determined from literature, is applicable for this experiment • Ceramic from APS process is more brittle compare to EB-PVD’s under constant loading condition

More Related