Mechanical Properties of Air Plasma Sprayed Environmental Barrier Coating (EBC) Systems: Preliminary Assessments

2015 ◽  
pp. 219-237 ◽  
Author(s):  
Bradley T. Richards ◽  
Dongming Zhu ◽  
Louis J. Ghosn ◽  
Haydn N.G. Wadley
Keyword(s):  
Mechanical Properties ◽  
Air Plasma ◽  
Environmental Barrier ◽  
Environmental Barrier Coating ◽  
Barrier Coating ◽  
Plasma Sprayed

Fatigue of an Advanced SiC/SiC Ceramic Matrix Composite With an Environmental Barrier Coating at Elevated Temperature in Air and in Steam

2020 ◽  
Author(s):  
T. M. Williams ◽  
M. B. Ruggles-Wrenn
Keyword(s):  
Ceramic Matrix Composite ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Air Plasma ◽  
Application Process ◽  
Environmental Barrier ◽  
Damage And Failure ◽  
Environmental Barrier Coating ◽  
Barrier Coating ◽  
Sic Ceramic

Abstract Uniaxial tension-tension fatigue performance of a SiC/SiC composite with an ytterbium-disilicate environmental barrier coating (EBC) was investigated at 1200°C in laboratory air and in steam. The composite is reinforced with Hi-Nicalon™ SiC fibers and has a melt-infiltrated matrix processed by chemical vapor infiltration of SiC followed by infiltration with SiC particulate slurry and molten Si. The EBC consists of a Si bond coat and an ytterbium disilicate (Yb2Si2O7) top coat applied via air plasma spraying (APS). Basic tensile properties of the EBC/SiC/SiC composite were evaluated at 1200°C. Tension-tension fatigue was examined for maximum stresses of 110–140 MPa in air and in steam. To assess the efficacy of the EBC, experimental results obtained for the coated composite are compared to those obtained for a control composite without the EBC. Surface grit-blasting inherent in the EBC application process degrades tensile strength of the composite. However, the EBC effectively protects the composite from oxidation embrittlement during cyclic loading in air or in steam. Fatigue runout defined as survival of 200,000 cycles (55.6 h at a frequency of 1.0 Hz) was achieved at 110 MPa in air and in steam. The retained properties of pre-fatigued specimens were characterized. Composite microstructure, as well as damage and failure mechanisms were investigated. Damage and failure of the EBC/SiC/SiC composite are attributed to growth of cracks originating from numerous processing defects (voids) present in the composite interior.

scholarly journals High-Temperature Low-Cycle Fatigue Behaviour of MAR-M247 Coated with Newly Developed Thermal and Environmental Barrier Coating

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Ivo Šulák ◽  
Karel Obrtlík ◽  
Ladislav Čelko ◽  
Pavel Gejdoš ◽  
David Jech
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Constant Strain Rate ◽  
Total Strain Amplitude ◽  
Average Thickness ◽  
Cycle Fatigue ◽  
Air Plasma ◽  
Environmental Barrier ◽  
Environmental Barrier Coating ◽  
Barrier Coating

This study investigates the strain-controlled low-cycle fatigue (LCF) behaviour of an untreated and surface-treated MAR-M247 superalloy in a symmetrical push-pull cycle with a constant strain rate at 900°C in laboratory air. A newly developed experimental thermal and environmental barrier coating (TEBC) system, consisting of a 170 μm thick CoNiCrAlY bond coat (BC) and a bilayer ceramic top coat (TC), with an interlayer and an upper layer, was deposited using air plasma spray techniques. The ceramic interlayer with an average thickness of 77 μm was formed from agglomerated and sintered yttria-stabilized zirconia. An experimental mixture of mullite (Al6Si2O13) and hexacelsian (BaAl2Si2O8) at a ratio of 70/30 vol.% was sprayed as the upper layer. The average thickness of the TC was 244 μm. The specimen sections were investigated using a TESCAN Lyra3 XMU scanning electron microscope (SEM) to characterise the microstructure of both the TEBC and the substrate material. The fatigue damage mechanisms in the TEBC-coated superalloy were studied. The fatigue life curves in the representation of the total strain amplitude versus the number of cycles to failure of the TEBC-coated and uncoated superalloy were assessed. TEBC was found to have a slight, positive effect on the fatigue life of MAR-M247.

HOT CORROSION OF CERIA-YTTRIA STABILIZED ZIRCONIA PLASMA SPRAYED THERMAL BARRIER COATING BY EUTECTIC VANDIUM PENTAOXIDE-SODIUM SULFATE

2018 ◽  
Vol 18 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Mohammed J Kadhim ◽  
Mohammed H Hafiz ◽  
Maryam A Ali Bash
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Monoclinic Phase ◽  
Volume Fraction ◽  
High Volume ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Plan View ◽  
Barrier Coating ◽  
Plasma Sprayed

The high temperature corrosion behavior of thermal barrier coating (TBC) systemconsisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coatwere characterized. The upper surfaces of CYSZ covered with 30 mg/cm2 , mixed 45 wt%Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC andinteraction times from 1 up to 8 h. The upper surface plan view of the coatings wereidentified for topography, roughness, chemical composition, phases and reaction productsusing scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-raydiffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed thephase transformation of nontransformable tetragonal (t') into monoclinic phase, presence ofYVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed theformation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.The formation of these compounds were combined with formation of monoclinic phase (m)from transformation of nontransformable tetragonal phase (t').

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