Effect of ceramic coating thickness on fracture behaviour of coating structure under thermal shock cycles

Abstract There are many instances of coatings that require a nondestructive and non-contact measure of coating thickness as part of a quality control system. Specifically, this paper reports on experiments carried out on non-contact measurements of MCrAIY and TBC coatings. The system uses an infra red beam from a solid state laser to generate a thermal wave in the coating. When this wave reaches the substrate an interference effect is caused. The modulated input heating produces a modulated output infra red signal from the surface and at a different wavelength from the laser beam. The output signal has a phase difference from the input signal which is related to the coating thickness. As neither the laser nor the detector are in contact with the surface of the coating and the temperature of the coating is raised by only a few degrees this represents a non-contact NDE system. This system has been tested across a range of coating/substrate combinations. In this paper we give examples of MCrAIY and TBC coatings applied to engine components demonstrating that the accuracy of measurement is only limited by the roughness of the coating structure and substrate. The use of this system for on-line measurement during the spraying process is also discussed and results presented.

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Thermal Shock Resistance of Cordierite-Mullite Refractory Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.290.260 ◽

2005 ◽

Vol 290 ◽

pp. 260-263 ◽

Cited By ~ 6

Author(s):

Zdeněk Chlup ◽

Ivo Dlouhý ◽

Aldo Roberto Boccaccini ◽

D.N. Boccaccini ◽

Cristina Leonelli ◽

...

Keyword(s):

Thermal Shock ◽

Fracture Behaviour ◽

Notched Specimen ◽

Composite Systems ◽

Microstructural Damage ◽

Component Systems ◽

Water Quench ◽

Mullite Refractory ◽

Shock Resistance ◽

Points Of View

The design of composite materials leads to the development of multi-component systems where each constituent has a specific function in the material, from technological and/or application points of view. Examples of such composite systems are the cordierite-mullite refractory materials investigated in this contribution. Two different commercially available compositions were selected for evaluation of the influence of microstructure on fracture behaviour under thermal shock conditions. The materials were exposed to water-quench tests from 1250°C and subsequently the fracture toughness was evaluated using the chevron notched specimen technique. The results were compared to those obtained on as-received materials. Microstructural damage was also studied applying fractographic techniques with the aim to gain knowledge on the thermal shock damage mechanisms acting in the materials.

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Finite Element Analysis of Ceramic Coating Systems Under Spherical Indentation With Metallic Interlayer: Part I — Uncracked Coatings

World Tribology Congress III, Volume 1 ◽

10.1115/wtc2005-64209 ◽

2005 ◽

Author(s):

Minh-Quy Le ◽

Jin-Woo Yi ◽

Seock-Sam Kim

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Coating Thickness ◽

Radial Stress ◽

Ceramic Coating ◽

Ceramic Coatings ◽

Spherical Indentation ◽

Model Parameters ◽

Element Analysis ◽

Plastic Damage

Spherical indentation problems of ceramic coatings/metallic inter-layer/ductile substrate were investigated numerically by axisymmetric finite element analysis (FEA) for two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel. Various indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. Radial stress distribution and plastic damage zones evolution were discussed in connection with model parameters. The results showed that the suitable metallic interlayer could improve resistance of ceramic coating systems through reducing the peak tensile radial stress on the surface and interface of ceramic coatings and plastic damage zone size in the substrate under spherical indentation.

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Influence of a Thermal Barrier Coating on the Performance of a Turboprop Engine

Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery ◽

10.1115/92-gt-038 ◽

1992 ◽

Author(s):

J. D. MacLeod ◽

J. C. G. Laflamme

Keyword(s):

Surface Roughness ◽

Thermal Barrier Coating ◽

Coating Thickness ◽

Ceramic Coating ◽

National Research Council ◽

Engine Performance ◽

Thermal Barrier ◽

Barrier Coating ◽

Project Objectives ◽

The Impact

Under the sponsorship of the Canadian Department of National Defence, the Engine Laboratory of the National Research Council of Canada has evaluated the influence of applying a thermal barrier coating on the performance of a gas turbine engine. The effort is aimed at quantifying the performance effects of a particular ceramic coating on the first stage turbine vanes. The long term objective of the program is to both assess the relative change in engine performance and compare against the claimed benefits of higher possible turbine inlet temperatures, longer time in service and increased time between overhauls. The engine used for this evaluation was the Allison T56 turboprop with the first stage turbine nozzles coated with the Chromalloy RT-33 ceramic coating. The issues addressed in testing this particular type of hot section coating were; 1) effect of coating thickness on nozzle effective flow area; 2) surface roughness influence on turbine efficiency; This paper describes the project objectives, the experimental installation, and the results of the performance evaluations. Discussed are performance variations due to coating thickness and surface roughness on engine performance characteristics. As the performance changes were small, a rigorous measurement uncertainty analysis is included. The coating application process, and the affected overhaul procedures are examined. The results of the pre- and post-coating turbine testing are presented, with a discussion of the impact on engine performance.

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Thermal Analysis of Ceramic Coated Aluminium Piston with Slots

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.786 ◽

2014 ◽

Vol 592-594 ◽

pp. 786-790

Author(s):

M.R. Chitthaarth ◽

K. Manivannan

Keyword(s):

Thermal Analysis ◽

Thermal Expansion ◽

Coating Thickness ◽

Ceramic Coating ◽

Working Condition ◽

Middle Layer ◽

Piston Crown ◽

Alsi Alloy ◽

Aluminium Piston ◽

Plasma Sprayed

The main aim is to control thermal expansion in aluminium piston at high working condition. A plasma sprayed ceramic coating (TBC) is applied on the piston crown as a top coat and NiCrAl is applied as the middle layer as bond coat to improve the addition strength between the top coat and the metal subtract layer as AlSi alloy; we introduce a thermal slot on the piston shrink to regulate the heat flow in piston and make it cooler. We analyse the piston with these two implementations to determine the thermal analysis of the piston. The results can be shown in the various comparisons of coating thickness of top coat with thermal slots on the piston shrink. Increase in coating thickness reduces the stress in the coatings. It is observed that 85°C increase in 0.8mm coat than the ordinary piston.

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Fabrication of Self-Healing Ceramic Coating Against Oxidation for Carbon/Carbon Composite Using Polysilazane and Fillers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.775 ◽

2009 ◽

Vol 79-82 ◽

pp. 775-778 ◽

Cited By ~ 1

Author(s):

Hong Li Liu ◽

Chun Ying Tian

Keyword(s):

Thermal Shock ◽

Thermal Shock Resistance ◽

Loss Rate ◽

Ceramic Coating ◽

Carbon Composite ◽

Self Healing ◽

Weight Loss Rate ◽

Shock Resistance ◽

Polymer Pyrolysis ◽

Sealing Layer

The self-healing ceramic coating against oxidation for carbon/carbon composite was fabricated via preceramic polymer pyrolysis process using polysilazane as preceramic and MoSi2, B4C powders as fillers. By means of SEM and XRD, the phase compose and microstructure of coating were characterized, and preliminarily study on its anti-oxidation ability and thermal shock resistance were conducted. The results showed that, the coating is composed of the resisting oxidation layer and the sealing layer. The thickness of the coating is about 50μm, and the coating is uniform and densified. Good contact at the interfaces is visible on the SEM photograph. At 1300°C temperature, the thermal shock resistance test was conducted 50 times, the weight loss rate was 2.12%. In range of 1200°C~1500°C, the anti oxidation ability of the coating is good.

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