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Title: Development of nondestructive evaluation methods for ceramic coatings.

Abstract

Various nondestructive evaluation (NDE) technologies are being developed to advance the knowledge of ceramic coatings for components in the hot gas-path of advanced, low-emission gas-fired turbine engines. The ceramic coating systems being studied by NDE include thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs). TBCs are under development for vanes, blades and combustor liners to allow hotter gas path temperatures and EBCs are under development to reduce environmental damage to high temperature components made of ceramic matrix composites (CMCs). Data provided by NDE methods will be used to: (a) provide data to assess reliability of new coating application processes, (b) identify defective components that could cause unscheduled outages (c) track growth rates of defects during use in engines and (d) allow rational judgement for replace/repair/re-use decisions of components.

Authors:
 [1]
  1. (Nuclear Engineering Division)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
FE
OSTI Identifier:
1007392
Report Number(s):
ANL/NE/CP-59794
TRN: US201106%%255
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 21st Annual Conference on Fossil Energy Materials; Apr. 30, 2007 - May 2, 2007; Knoxville, TN
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; CERAMICS; COATINGS; COMBUSTORS; DEFECTS; ENGINES; EVALUATION; LINERS; RELIABILITY; THERMAL BARRIERS; TURBINES; VANES

Citation Formats

Sun, J. G. Development of nondestructive evaluation methods for ceramic coatings.. United States: N. p., 2007. Web.
Sun, J. G. Development of nondestructive evaluation methods for ceramic coatings.. United States.
Sun, J. G. Mon . "Development of nondestructive evaluation methods for ceramic coatings.". United States. doi:.
@article{osti_1007392,
title = {Development of nondestructive evaluation methods for ceramic coatings.},
author = {Sun, J. G.},
abstractNote = {Various nondestructive evaluation (NDE) technologies are being developed to advance the knowledge of ceramic coatings for components in the hot gas-path of advanced, low-emission gas-fired turbine engines. The ceramic coating systems being studied by NDE include thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs). TBCs are under development for vanes, blades and combustor liners to allow hotter gas path temperatures and EBCs are under development to reduce environmental damage to high temperature components made of ceramic matrix composites (CMCs). Data provided by NDE methods will be used to: (a) provide data to assess reliability of new coating application processes, (b) identify defective components that could cause unscheduled outages (c) track growth rates of defects during use in engines and (d) allow rational judgement for replace/repair/re-use decisions of components.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • Various nondestructive evaluation (NDE) technologies are being developed to study the use of ceramic coatings on components in the hot-gas path of advanced low-emission gas-fired turbines. The types of ceramic coatings include thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs). TBCs are under development for vanes, blades, and combustor liners to allow hotter gas-path temperatures, and EBCs are under development to reduce environmental damage to high-temperature components made of ceramic matrix composites. The NDE methods will be used to (a) provide data to assess the reliability of new coating application processes, (b) identify defective components that could cause unscheduledmore » outages, (c) track growth rates of defects during component use in engines, and (d) allow rational judgment for replace/repair/re-use decisions regarding components. Advances in TBC application, both electron beam-physical vapor deposition (EB-PVD) and air plasma spraying (APS), are allowing higher temperatures in the hot-gas path. However, as TBCs become ''prime reliant,'' their condition at scheduled or unscheduled outages must be known. NDE methods are under development to assess the condition of the TBC for pre-spall conditions. EB-PVD test samples with up to 70 thermal cycles have been studied by a newly developed method involving polarized laser back-scatter NDE. Results suggest a correlation between the NDE laser data and the TBC/bond-coat topography. This finding is important because several theories directed toward understanding the pre-spall condition suggest that the topography in the thermally grown oxide layer changes significantly as a function of the number of thermal cycles. Tests have also been conducted with this NDE method on APS TBCs. Results suggest that the pre-spall condition is detected for these coatings. One-sided, high-speed thermal imaging also has shown promise for NDE of APS coatings. Testing of SiC/SiC composites for combustor liners has demonstrated that environmental EBCs are required to reduce oxidation-induced recession rates. NDE technologies, primarily one-sided and through-thickness thermal imaging, are under development to detect delaminations and degradation of EBCs. Recent results have demonstrated that NDE thermal image data correctly detected pre-spall regions of a barium-strontium-alumino-silicate coating on melt-infiltrated SiC/SiC. The NDE data were verified with field test data from a combustor liner in a 4.5 MW(e) natural-gas-fired turbine. The shape of the spalled EBC region and the growth of the spalled EBC region after various engine run times were correlated with boroscope image data from field tests. An effort has recently been started to address NDE development for oxide/oxide ceramic composites with an EBC. We will discuss the NDE methods under development for TBCs, recent NDE test results from thermally cycled TBCs, NDE results from EBCs on SiC/SiC, and the new effort directed toward oxide/oxide materials.« less
  • Functional failure of parts or components fabricated from ceramics is most often traced to defects (e.g., inclusions, undesirable density gradients, cracks, poor binder/plasticizer distributions, etc.) introduced in the early processing steps. Detection of these defects, especially in the green state, and elimination of the source of these defects will improve the economics as well as the reliability of advanced ceramics.
  • A discussion is given of the developments in the construction and improvement of experimental equipment to permit extensions of techniques previously used. Activities have included experimentation with impervious coatings to permit surface wave techniques to be used with the relatively porous zirconium oxide coating, and tests of the oxidation resistance of Chromalloy W-2. (B.O.G.)
  • A summary is presented of work conducted in developing ultrasonic methods for determining ceramic-metal bond strength and uniformity. Consideration was given to the differences between flame-sprayed and vapor- deposited coatings. Surface wave studies were divided into theoretical and empirical investigations. Apparatus to generate impact loads in the bonds were designed and constructed. Quartz crystals are to be used to detect the impact stresses and to determine bond conditions. A Schlieren system was constructed to permit more extensive use of higher ultrasonic frequencies. (B.O.G.)