scholarly journals Thermomechanical fatigue characterization of zirconia (8%Y2O3-ZrO2) and mullite thermal barrier coatings on diesel engine components: Effect of coatings on engine performance

2000 ◽  
Vol 214 (5) ◽  
pp. 729-742 ◽  
Author(s):  
P Ramaswamy ◽  
S Seetharamu ◽  
K B R Verma ◽  
N Raman ◽  
K J Rao
Keyword(s):  
Diesel Engine ◽  
Thermal Barrier Coatings ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
X Ray ◽  
Piston Head ◽  
Mullite Coatings ◽  
Engine Components

8%Y2O3-stabilized zirconia (8YPSZ) and mullite (3Al2O3·2SiO2) powders, which were made plasma sprayable by using an organic binder (polyvinyl alcohol), have been plasma spray coated on to the piston head, valves and cylinder head of a 3.8kW single-cylinder diesel engine, previously coated with Ni-Cr-Al-Y bond coat. The engine with components coated with 250 μm thick 8YPSZ and 1 mm thick mullite thermal barrier coatings has been evaluated for fuel efficiency and for endurance during 500 h long rigorous tests. Improved fuel efficiency was shown by the engine with coated components and the results are discussed. The coatings and the coated components have also been examined for phases, microstructure and chemical composition by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). Mullite coatings were found to exhibit increased resistance to microcracking compared with 8YPSZ during the 500 h endurance test.

Effect of Aluminum Phosphate Sealing Treatment on Properties of Thick Thermal Barrier Coatings

2000 ◽  
Author(s):  
S. Ahmaniemi ◽  
E. Rajamäki ◽  
P. Vuoristo ◽  
T. Mäntylä
Keyword(s):  
Corrosion Resistance ◽  
Diesel Engine ◽  
Thermal Barrier Coatings ◽  
Hot Corrosion ◽  
Aluminum Phosphate ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
X Ray ◽  
Sealing Treatment

Abstract Partially stabilized zirconia (8Y2O3-ZrO2) coatings were studied as thick thermal barrier coatings (TTBCs) for diesel engine applications. To improve the hot corrosion resistance of TTBCs the 1 mm thick yttria stabilized zirconia coating was densified with aluminum phosphate based sealant. Combined with better hot corrosion resistance other benefits obtained with sealing treatment are improved adhesion as well as increased mechanical properties of the ceramic layer. Three aluminum phosphate based sealants were investigated with varying viscosity level. Different sealant viscosities were used to optimize the level of sealant penetration into the coating. Sealant penetration and the violence of the reaction were determined by XRD, SEM/EDS and optical microscopy. The hardness profile from bond coat to the surface of the top layer was determined. Coating microstructure and phase structure were characterized by optical microscopy and by X-ray diffraction. Microhardness and porosity were determined. Residual stress states were measured by X-ray based stress analyzer. Bond strength of the coatings was determined with tensile test equipment. To simulate the diesel engine combustion conditions, hot corrosion tests were performed for the sealed TTBCs. Hot corrosion resistance of the coating was tested in isothermal exposure of 60Na2SO4 - 40V2O5 melt for 48 hours at 600 °C.

scholarly journals Investigation of Hot Section (Nozzle Guiding Vane) Distress due to Interaction of Thermal Barrier Coatings with CMAS

2018 ◽  
Vol 778 ◽  
pp. 245-250
Author(s):  
Qadeer Ahmed ◽  
Imran Nazir Qureshi ◽  
Iftichar Us Salam
Keyword(s):  
Thermal Barrier Coatings ◽  
Optical Emission ◽  
Turbine Engines ◽  
Thermal Barrier ◽  
Gas Turbine Engines ◽  
X Ray Diffraction ◽  
Barrier Coatings ◽  
X Ray ◽  
Cause Of Failure ◽  
Engine Components

An investigation of distress of hot section nozzle guiding vane (NGV) was carried out. Thermal barrier coatings (TBCs) were applied to the components of gas turbine engines to operate at higher temperatures i.e. up to 1200°C. The cause of failure was hot corrosion of TBCs by chemical entities from atmosphere like oxides of Al, Ca, Si and Mg (CMAS). Source of CMAS was dust, which was ingested to airfoil engine components. Different techniques like scanning electron microscope, boroscopy, optical microscopy, X-ray Diffraction and optical emission spectroscopy were utilized to investigate the failure of nozzle guiding vanes.

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