Monitoring Diffusion Coating Aging With Multi-Frequency Eddy Current MWM Sensors

2005 ◽  
Author(s):  
Vladimir Zilberstein ◽  
Robert Lyons ◽  
Andrew Washabaugh ◽  
Dave Grundy ◽  
Chris Craven ◽  
...  
Keyword(s):  
Eddy Current ◽  
Gas Turbines ◽  
Nickel Aluminide ◽  
Single Channel ◽  
Diffusion Coating ◽  
Diffusion Coatings ◽  
Aluminide Coatings ◽  
Wide Range ◽  
Before And After

Diffusion coatings are widely used to protect hot gas path components in land-based gas turbines and jet engines. Effective nondestructive assessment of the aged coating and substrate condition is critical for support of refurbish/replace/run decisions. In this paper, we present results on aging characterization of nickel aluminide and platinum aluminide coatings. The measurements were performed using a Meandering Winding Magnetometer (MWM®) eddy current sensor over a wide range of frequencies. Single-channel MWM sensors and multichannel imaging MWM-Arrays permit tracking of features of interest for a population of components and provide new capabilities for inspecting gas turbine components. These conformable sensors allow convenient manual and automated inspection on complex surfaces. Results on coating aging assessment suggest that the multiple frequency MWM technique can be implemented for characterization of diffusion coatings and base metals before and after component refurbishment.

Thermal Stability of NiAl-Base Coatings for High Temperature Application

2005 ◽  
Vol 237-240 ◽  
pp. 709-714
Author(s):  
Robert Filipek ◽  
Marek Danielewski ◽  
E. Tyliszczak ◽  
M. Pawełkiewicz ◽  
S. Datta
Keyword(s):  
Thermal Stability ◽  
Gas Turbines ◽  
Inverse Method ◽  
Critical Role ◽  
Diffusion Coatings ◽  
Aluminide Coatings ◽  
Wide Range ◽  
Industrial Energy ◽  
Temperature Application ◽  
Thermal Stability Of

Aluminide diffusion coatings act as a remedy against the aggressive environments in which modern aero-gas turbines operate. Platinum addition to basic aluminide coatings significantly improves the oxidation resistance of these coatings. The increase in operating temperatures of industrial energy systems and gas turbines, has led to the extensive use of coatings capable of providing improved service life. Interdiffusion plays a critical role in understanding the integrity of such coatings. The Danielewski-Holly model of interdiffusion which allows for the description of a wide range of processes (including processes stimulated by reactions at interfaces) is employed for studying of interdiffusion in the Pt-modified β-NiAl coatings. Using the inverse method the intrinsic diffusivities of Ni, Al and Pt were calculated. Such obtained diffusivities were subsequently used for modelling of thermal stability of Pt-modified aluminide coatings in air and in argon atmosphere.

scholarly journals Comparison of Above-Water Seabird and TriOS Radiometers along an Atlantic Meridional Transect

2020 ◽  
Vol 12 (10) ◽  
pp. 1669
Author(s):  
Krista Alikas ◽  
Viktor Vabson ◽  
Ilmar Ansko ◽  
Gavin H. Tilstone ◽  
Giorgio Dall’Olmo ◽  
...  
Keyword(s):  
State Of The Art ◽  
Ocean Color ◽  
Percentage Difference ◽  
Wide Range ◽  
Before And After ◽  
Reference Measurements ◽  
Satellite Ocean Color ◽  
Good Agreement

The Fiducial Reference Measurements for Satellite Ocean Color (FRM4SOC) project has carried out a range of activities to evaluate and improve the state-of-the-art in ocean color radiometry. This paper described the results from a ship-based intercomparison conducted on the Atlantic Meridional Transect 27 from 23rd September to 5th November 2017. Two different radiometric systems, TriOS-Radiation Measurement Sensor with Enhanced Spectral resolution (RAMSES) and Seabird-Hyperspectral Surface Acquisition System (HyperSAS), were compared and operated side-by-side over a wide range of Atlantic provinces and environmental conditions. Both systems were calibrated for traceability to SI (Système international) units at the same optical laboratory under uniform conditions before and after the field campaign. The in situ results and their accompanying uncertainties were evaluated using the same data handling protocols. The field data revealed variability in the responsivity between TRiOS and Seabird sensors, which is dependent on the ambient environmental and illumination conditions. The straylight effects for individual sensors were mostly within ±3%. A near infra-red (NIR) similarity correction changed the water-leaving reflectance (ρw) and water-leaving radiance (Lw) spectra significantly, bringing also a convergence in outliers. For improving the estimates of in situ uncertainty, it is recommended that additional characterization of radiometers and environmental ancillary measurements are undertaken. In general, the comparison of radiometric systems showed agreement within the evaluated uncertainty limits. Consistency of in situ results with the available Sentinel-3A Ocean and Land Color Instrument (OLCI) data in the range from (400…560) nm was also satisfactory (−8% < Mean Percentage Difference (MPD) < 15%) and showed good agreement in terms of the shape of the spectra and absolute values.

Qualification of a Frequency Scanning Eddy Current Equipment for Nondestructive Characterization of New and Serviced High-Temperature Coatings

2001 ◽  
Author(s):  
Giampiero Antonelli ◽  
Paola Crisafulli ◽  
Giacomo Tirone
Keyword(s):  
High Temperature ◽  
Eddy Current ◽  
Gas Turbines ◽  
Structural Damage ◽  
Economic Losses ◽  
Thermal Barriers ◽  
Frequency Scanning ◽  
Non Destructive ◽  
Equipment Qualification

As modern gas turbines are continuously being upgraded, mainly through the increase of their firing temperature and cooling optimization, the prime protection of the high technology and high-cost hot gas path parts is increasingly being transferred to the coatings. In order to avoid the risk of structural damage of these components, with its potential for greater economic losses — mostly traceable to unexpected prime time outages — refurbishment cycle should be dictated by the amount of the life actually expended by the coating. To address the issues of quality and condition assessment of new and serviced high-temperature coatings applied on buckets and vanes, an innovative non-destructive system was developed based on a frequency scanning eddy current technique. It combines outstanding high frequency hardware with model based analysis of raw data. In the paper, quantitative data on equipment qualification are presented, relating to its capability in measuring both the thickness and β-aluminide depletion of MCrAlY coatings applied on Ni-base superalloys. The results of an inspection campaign on serviced blades, performed during major overhauls of ENEL gas turbines, will also be reported, together with recent system upgrades, aiming at extending its applicability to newer coatings such as thermal barriers and over-aluminized MCrAlY’s.

Pulsed Eddy-Current Measurements of Corrosion and Cracking in Aging Aircraft

1997 ◽  
Vol 503 ◽  
Author(s):  
J. C. Moulder ◽  
J. A. Bieber
Keyword(s):  
Eddy Current ◽  
Current System ◽  
Fatigue Cracks ◽  
Single Frequency ◽  
Pulsed Eddy Current ◽  
Wide Range ◽  
Lift Off ◽  
Hidden Corrosion ◽  
Time Gating

ABSTRACTPulsed, or transient eddy-current methods are an effective tool for quantitative characterization of hidden corrosion and cracking in multi-layer aircraft structures. Eddy currents are the method of choice for this task, since they penetrate multiple layers of metal, whether or not the layers are mechanically bonded. The pulsed eddy-current technique is an important advance over conventional eddy-current methods because it rapidly acquires data over a wide range of frequencies, thereby providing more information than a conventional, single-frequency eddy-current instrument. We have combined a pulsed eddy-current instrument with a portable two-axis scanner to produce an instrument capable of rapidly scanning aircraft lap splices in situ, producing pseudo-color images that reveal hidden corrosion or cracking. A unique feature of time-domain eddy-current data is the ability to selectively filter clutter from the image by time-gating the pulsed signal. Time-gating permits the user to select the inspection depth, thereby eliminating interference from upper layers, air gaps, lift-off variation and fasteners. By using a theoretical model of the pulsed eddy-current system, it is possible to interpret the data quantitatively, yielding quantitative maps of corrosion damage. Some of the same advantages of the pulsed eddycurrent technique apply to the characterization of hidden fatigue cracks as well, although the tieory for crack signals is less advanced.

Si diffusion coating on steels by SiH4/H2 treatment for high temperature oxidation protection

1990 ◽  
Vol 5 (1) ◽  
pp. 74-82 ◽  
Author(s):  
A. L. Cabrera ◽  
J. F. Kirner ◽  
R. Pierantozzi
Keyword(s):  
High Temperatures ◽  
Diffusion Coating ◽  
Depth Profiling ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
Diffusion Coatings ◽  
Composition And Structure

The reaction of SiH4/H2 mixtures with iron and steels was studied at a total pressure of 1 atm and temperatures above 500 °C. When the amount of water vapor in the gas mixture is carefully controlled, a metal silicide diffusion coating forms at low temperatures (below 900°C). Composition and structure of the Si diffusion coatings were determined with Auger depth profiling and x-ray diffraction. Kinetics of the surface reaction between SiH4, and the metal substrate as well as the behavior of these films in severe environments at high temperatures were studied by a microgravimetric technique. Characterization of these Si coatings on iron, low carbon steel (1010), 9% Cr/1% Mo steel (alloy A182F9), and stainless steels (310) and their applications to reduce oxidation, nitriding, or coking at high temperatures or corrosion in mineral acids are described.

Elaboration of Nickel Aluminide Diffusion Coatings: Application to Oxidation Resistance

2008 ◽  
Vol 595-598 ◽  
pp. 41-49 ◽  
Author(s):  
Céline Choux ◽  
Sébastien Chevalier ◽  
Yannik Cadoret
Keyword(s):  
High Temperature ◽  
Nickel Aluminide ◽  
Diffusion Mechanism ◽  
Alumina Scale ◽  
Organic Chemical ◽  
Material Surface ◽  
Protective Oxide ◽  
Diffusion Coatings ◽  
Aluminide Coatings ◽  
Α Al2o3

Aluminide diffusion coatings are widely used in aeronautic domain. Nickel based superalloys present good mechanical properties and creep resistance at high temperature but their corrosion resistance is somewhat poor. In order to enhance their lifetime at high temperature, aluminide coatings can be applied on alloy surface. Aluminium present on material surface can form, at high temperature, alumina scale which is a protective oxide scale. In the present study, nickel aluminide coatings were carried out by aluminisation in a single step pack cementation process on nickel based superalloys 600 and AM1. Ni-Al intermetallic was obtained in each case. Oxidation tests were carried out at 900°C in air under atmospheric pressure. At this temperature, transient alumina as γ-Al2O3 and θ-Al2O3 appear on surface and are less protective than the stable α- Al2O3. Reactive elements can enhance α-Al2O3 nucleation and change diffusion mechanism during oxidation leading to a better adherence of alumina scale. In the present work, yttria was introduced by Metal-Organic Chemical Vapour Deposition (MOCVD) prior to the aluminisation. Yttria doped and undoped sample behaviours were compared under oxidising atmospheres.

scholarly journals Thermo-Mechanical Characterizations of Coatings for HP Turbines

1998 ◽  
Author(s):  
A. Boudot ◽  
F. Crabos ◽  
D. Fournier ◽  
D. Monceau
Keyword(s):  
Single Crystal ◽  
Great Influence ◽  
Tensile Tests ◽  
Diffusion Coatings ◽  
Brittle Transition ◽  
Aluminide Coatings ◽  
Transition Strain ◽  
Before And After ◽  
Coating Microstructure ◽  
Plasma Sprayed

Three different coatings were studied in this work: vacuum plasma-sprayed NiCoCrAlYTa, electrolytically deposited NiCoCrAlYTa and Ni-Pt aluminide diffusion coatings. These three coatings were deposited on AM3 single crystal alloy. The tensile properties of coated single crystal test specimens were investigated. Ductile to Brittle Transition Temperatures (DBTT) were determined from tensile tests. All the coatings were examined before and after testing. All the tested coatings induce a ductile/brittle transition. Strain rate has a great influence on the transition temperature. The comparison between plasma-sprayed deposition and electrodeposition illustrates the strong influence of coating microstructure. In every case, NiCoCrAlYTa coatings were more ductile, and then less detrimental, than aluminide coatings.

Pack Cementation Coatings for Superalloys: A Review of History, Theory, and Practice

1988 ◽  
Vol 110 (1) ◽  
pp. 150-154 ◽  
Author(s):  
G. W. Goward ◽  
L. W. Cannon
Keyword(s):  
Gas Turbines ◽  
Large Scale ◽  
Aircraft Engine ◽  
Pack Cementation ◽  
Theory And Practice ◽  
Chromium Diffusion ◽  
Diffusion Coatings ◽  
Aluminide Coatings ◽  
Marine Engines ◽  
Overlay Coatings

Nickel and cobalt-base superalloy blades and vanes in the hot sections of all gas turbines are coated to enhance resistance to hot corrosion. Pack cementation aluminizing, invented in 1911, is the most widely used coating process. Corrosion resistance of aluminide coatings can be increased by modification with chromium, platinum, or silicon. Chromium diffusion coatings can be used at lower temperatures. Formation and degradation mechanisms are reasonably well understood and large-scale manufacturing processes for these coatings are gradually being automated. Pack cementation and related diffusion coatings serve well for most aircraft engine applications. The trend for industrial and marine engines is more toward the use of overlay coatings because of the greater ease of designing these to meet a wide variety of corrosion conditions.

An Electron Microscope Study of Interdiffusion and Compound Formation in Ta-Au Thin Films

1973 ◽  
Vol 31 ◽  
pp. 32-33 ◽  
Author(s):  
T. C. Tisone ◽  
S. Lau
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Thermally Grown Oxide ◽  
Ion Milling ◽  
Compound Formation ◽  
Technology Application ◽  
Transmission Electron ◽  
Before And After ◽  
Au Thin Films

In a study of the properties of a Ta-Au metallization system for thin film technology application, the interdiffusion between Ta(bcc)-Au, βTa-Au and Ta2M-Au films was studied. Considered here is a discussion of the use of the transmission electron microscope(TEM) in the identification of phases formed and characterization of the film microstructures before and after annealing.The films were deposited by sputtering onto silicon wafers with 5000 Å of thermally grown oxide. The film thicknesses were 2000 Å of Ta and 2000 Å of Au. Samples for TEM observation were prepared by ultrasonically cutting 3mm disks from the wafers. The disks were first chemically etched from the silicon side using a HNO3 :HF(19:5) solution followed by ion milling to perforation of the Au side.

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