Inhibition of Interdiffusion From MCrAlY Overlay Coatings by Application of a Ni-Re Interlayer

1999 ◽  
Vol 121 (2) ◽  
pp. 313-319 ◽  
Author(s):  
R. A. Page ◽  
G. R. Leverant
Keyword(s):  
Aluminum Content ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Critical Issue ◽  
Al2o3 Scale ◽  
Depletion Zone ◽  
Mcraly Coating ◽  
Order Of Magnitude ◽  
Thin Interlayer ◽  
Overlay Coatings

The durability of protective coatings on combustion turbine blades and vanes is a critical issue in the power generation industry. Coating life usually dictates the refurbishment intervals for these components, and these intervals have generally been of shorter duration than desired by the operators of the equipment. Both MCrAlY and aluminide type coatings protect against oxidation and hot corrosion by forming a protective Al2O3 surface layer. Degradation of the coatings occurs by depletion of the aluminum content of the coating through interdiffusion with the substrate and through the formation and spallation of an external Al2O3 scale. The results obtained in this study clearly show that the application of a thin interlayer of Ni-Re beneath the MCrAlY coating can significantly decrease the growth rate of the inner β-NiAl depletion zone. Order of magnitude reductions in the inner depletion zone thickness formed at 1000 h were obtained with both the Ni-32 wt.% Re and the Ni-47 wt.% Re interlayer coatings. Since formation of the inner depletion zone is believed to result from interdiffusion with the substrate, these results suggest that the Ni-Re interlayer provided a significant impediment to the inward diffusion of Al into the substrate.

scholarly journals Inhibition of Interdiffusion From MCrAlY Overlay Coatings by Application of a Ni-Re Interlayer

1998 ◽  
Author(s):  
Richard A. Page ◽  
Gerald R. Leverant
Keyword(s):  
Aluminum Content ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Critical Issue ◽  
Al2o3 Scale ◽  
Depletion Zone ◽  
Mcraly Coating ◽  
Order Of Magnitude ◽  
Thin Interlayer ◽  
Overlay Coatings

The durability of protective coatings on combustion turbine blades and vanes is a critical issue in the power generation industry. Coating life usually dictates the refurbishment intervals for these components, and these intervals have generally been of shorter duration than desired by the operators of the equipment. Both MCrAlY and aluminide type coatings protect against oxidation and hot corrosion by forming a protective Al2O3 surface layer. Degradation of the coatings occurs by depletion of the aluminum content of the coating through interdiffusion with the substrate and through the formation and spallation of an external Al2O3 scale. The results obtained in this study clearly show that the application of a thin interlayer of Ni-Re beneath the MCrAlY coating can significantly decrease the growth rate of the inner β-NiAl depletion zone. Order of magnitude reductions in the inner depletion zone thickness formed at 1000 hours were obtained with both the Ni-32 wt.% Re and the Ni-47 wt% Re interlayer coatings. Since formation of the inner depletion zone is believed to result from interdiffusion with the substrate, these results suggest that the Ni-Re interlayer provided a significant impediment to the inward diffusion of Al into the substrate.

Heat resistance of gas turbine blades with protective coatings

1986 ◽  
Vol 18 (5) ◽  
pp. 610-615 ◽  
Author(s):  
A. P. Voloshchenko ◽  
G. N. Tret'yachenko ◽  
L. B. Getsov ◽  
B. M. Zinchenko ◽  
I. S. Malashenko ◽  
...  
Keyword(s):  
Heat Resistance ◽  
Gas Turbine ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Gas Turbine Blades

scholarly journals Effect of machine hammer peening on the surface integrity of a ZnAl-based corrosion protective coating

2020 ◽  
Vol 318 ◽  
pp. 01008
Author(s):  
Alina Timmermann ◽  
Mohamed Abdulgader ◽  
Leif Hagen ◽  
Alexander Koch ◽  
Philipp Wittke ◽  
...  
Keyword(s):  
Corrosion Fatigue ◽  
Surface Integrity ◽  
Protective Coatings ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Fatigue Properties ◽  
Machine Hammer Peening ◽  
Coated Surfaces ◽  
Thermally Sprayed ◽  
Hammer Peening

Thermally sprayed protective coatings are applied onto many mechanically stressed components such as support structures, shafts, turbine blades or heat exchangers. In addition to the static or cyclic load, a superimposition with corrosion processes occurs in many cases. Thermal sprayed ZnAl coatings are known for their performant corrosion protection properties. Within this context, the potential of ZnAl-based layer systems was analyzed regarding corrosion fatigue behavior. Therefore, a timeand cost-efficient testing strategy based on a corrosion-superimposed load increase procedure was used to estimate the effects of a corrosive attack during cyclic loading. The investigated coating systems were thermally sprayed and partially post-processed with a Machine Hammer Peening (MHP) operation. This treatment was identified as an appropriate technique for compressing and smoothing coated surfaces. The inter-relationships between the parametrization of the MHP process, the resulting surface integrity, and the estimated corrosion fatigue properties were analyzed. The investigations indicate a positive effect of MHP post-processing operations on the surface properties of the ZnAl-based coating system.

Rainbow Field Test of Coatings for Hot Corrosion Protection of Gas Turbine Hot Section Components

1987 ◽  
Author(s):  
Mark Van Roode ◽  
Kenneth G. Kubarych ◽  
Russell L. McCarron
Keyword(s):  
Gas Turbine ◽  
Corrosion Protection ◽  
Field Test ◽  
Hot Corrosion ◽  
Physical Vapor Deposition ◽  
Turbine Blades ◽  
Field Testing ◽  
Gas Turbine Blades ◽  
Metal Aluminides ◽  
Overlay Coatings

The work described in this paper was conducted under Electric Power Research Institute (EPRI) Contract RP 2465, “Rainbow Test of Advanced Coatings for Gas Turbine Blades and Vanes”. A field test of a rainbow rotor and nozzle was carried out to establish the hot corrosion protection of various aluminide and MCrAlX (X = Y, Hf) overlay coatings on first stage blades and nozzles of a Centaur gas turbine operating in Valera, Venezuela. The blade coatings included both simple and precious metal aluminides, Electron Beam-Physical Vapor Deposition (EB-PVD) coatings and Low Pressure Plasma Spray (LPPS) coatings on Inconel-738LC, Inconel-792 and MAR-M421 substrates. The turbine nozzle vanes were coated by similar methods on FSX-414 and MAR-M509 substrates. Field testing was performed under industrial conditions where the continuous duty engine, used for power generation, ran on a liquid fuel contaminated with sodium and sulfur. The engine test was terminated after nearly 8,000 hours of operation. Visual examination and micro-structural analysis indicated that EB-PVD and LPPS overlay coatings were more effective than simple and modified aluminides for hot section hot corrosion protection. The protection of overlay coatings on nozzle airfoils was found to increase with their chromium content.

Assessing of Hot Gas Parts Using Advanced Eddy Current Testing Methods

2008 ◽  
Author(s):  
Matthias Jungbluth ◽  
Vinay Jonnalagadda ◽  
Erwan Baleine ◽  
Mattias Broddega˚rd ◽  
Rolf Wilkenho¨ner ◽  
...  
Keyword(s):  
Eddy Current ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Diagnostic Methods ◽  
Design Parameters ◽  
Gas Temperature ◽  
Diagnostic Measures ◽  
Hot Gas

The turbine section of state-of-the-art industrial gas turbines is exposed to the most severe conditions such as high temperatures, corrosive environments and high mechanical stresses for several tens of thousands of hours. To withstand these conditions, turbine blades and vanes have become the most sophisticated parts. This, together with advanced manufacturing technologies, strict quality requirements and maximum reliability demands, affects costs. Different design features have been realized in the past to meet the ambitious requirements, and are also under constant development. Blades and vanes made of superalloys with directionally-solidified or single-crystal structure are used to provide highest strengths at temperatures as near as possible to the hot gas temperature. The high integrity and conformity of the parts are required to realize the material potential. Different advanced diagnostic methods are applied to ensure these over time. Another way to increase the operating temperatures of gas turbines is the application of corrosion and thermal protection coatings for one or several rows of the blades and vanes. Deviations in the specified coating thickness tend to reduce the lifetime of such coatings significantly. Hence, the monitoring of this property during the manufacturing requires special nondestructive diagnostic measures. Service exposed parts, which need to be refurbished when the protective coatings are spent, offer a significant operation potential after refurbishment. To guarantee the design parameters during the next service interval, several nondestructive material evaluation methods are available for the necessary part property assessment. Multifrequency Eddy Current has proven itself as an appropriate NDE technique to accomplish the above diagnostic requirements. The paper will give an overview of results gained at Siemens with model based Eddy Current methods using measurement systems developed by Jentek Sensors Inc., USA, and CESI, Italy. Potential applications and limitations of the method also will be discussed.

Coating Rejuvenation: New Repair Technology for High Pressure Turbine Blades

2000 ◽  
Author(s):  
Jeffrey A. Conner ◽  
Michael J. Weimer
Keyword(s):  
High Pressure ◽  
Life Cycle ◽  
Wall Thickness ◽  
Life Cycle Cost ◽  
Protective Coatings ◽  
Turbine Blades ◽  
High Pressure Turbine ◽  
Aluminide Coatings ◽  
Patent Applications ◽  
Blade Repair

With the evolution of advanced directionally solidified and single crystal nickel base superalloy turbine blades, managing life cycle costs of high pressure turbine (HPT) blades has become increasingly more difficult. Today’s advanced high pressure turbine blades in aero and aero-derivative turbines feature thin walls (<.030 inches), complex internal geometries, three dimensional (3D) aerodynamic shapes, multiple protective coatings and complex film cooling schemes. A major contributor to blade life cycle cost is the ability to perform multiple repairs without compromising the integrity of these complex components. Repair of HPT blades has traditionally fallen into two categories: mini or partial repairs where blade tips are restored and coated, and full repairs where flowpath coatings are removed, blade tips restored and new coating(s) applied to flowpath surfaces. Historically, the number of full repairs allowed ranges from zero to two based on numerous design considerations, one of which is maintaining a minimum wall thickness. Removal of protective coatings during full repair reduces wall thickness which limits the number of times a full repair can be performed. Furthermore, blades that have sufficient design allowance to permit two full repairs typically have very low yields at the second full repair due to thinning of airfoil walls below minimum thickness limits. The life of a given HPT blade is therefore controlled to a large degree by at what shop visit a full repair is performed. GE Engine Services has developed a new blade repair approach — Coating Rejuvenation — which significantly extends blade life by restoring protective coatings and maintaining wall thickness. Included in the Coating Rejuvenation repair are technologies that allow: removal of physical vapor deposited (PVD) thermal barrier coatings from external surfaces and cooling holes without impacting the bond coat; removal of oxidation and corrosion products from engine exposed coatings without impacting adjacent intact coating; restoration of coating composition to optimize environmental resistance; and upgrade of existing aluminide coatings to platinum aluminide coatings without removal of the existing coating. Combined together, these technologies can be used to support a comprehensive blade repair workscope plan that dramatically increases the life of HPT blades and decreases the life cycle cost for these components. Overviews of these technologies are presented in this paper along with information on how the technology was matured. Due to pending patent applications with the US Patent & Trademark Office as well as pending patent applications in other countries, significant technical detail cannot be presented at this time.

An X-ray study of residual macrostresses in protective coatings for gas-turbine blades

1997 ◽  
Vol 39 (11) ◽  
pp. 484-488
Author(s):  
Yu. D. Yagodkin ◽  
K. M. Pastukhov ◽  
E. V. Milyaeva ◽  
S. A. Muboyadzhyan ◽  
S. A. Budinovskii
Keyword(s):  
Gas Turbine ◽  
Protective Coatings ◽  
Turbine Blades ◽  
X Ray ◽  
Gas Turbine Blades ◽  
Residual Macrostresses

scholarly journals Comparative study of protective coatings for heat resistance

2020 ◽  
Vol 23 (1) ◽  
pp. 41-48
Author(s):  
A. V. Zorichev ◽  
G. T. Pashchenko ◽  
O. A. Parfenovskaya ◽  
V. M. Samoylenko ◽  
T. I. Golovneva
Keyword(s):  
Phase Composition ◽  
Heat Resistance ◽  
Temperature Change ◽  
Thermal Fatigue ◽  
Protective Coatings ◽  
Fatigue Cracks ◽  
Turbine Blades ◽  
Cyclic Temperature ◽  
Thermal Fatigue Cracks ◽  
Cyclic Temperature Change

Modern gas turbine engines operate under changing temperature loads. Therefore, one of the important characteristics of the protective coatings used on the turbine blades is their high resistance to the occurrence and development of cracks under mechanical and thermal loads. The applied effective systems of internal heat removal of the cooled turbine blades lead to an increase in their heat stress. At present, cracks arising from thermal fatigue are one of the common defects of the protective coatings used on turbine blades. The heat resistance of coatings at high temperatures is determined by three factors: the shape of the part on which the coating is applied, the thickness of the coating and the phase composition of the surface layers or the maximum aluminum content in the coating. Therefore, when choosing a protective coating for these operating conditions, it is important to know the impact of these factors on the thermal stability of the coating. The paper presents a comparative study of various coatings on their resistance to crack formation under cyclic temperature change. The dependence of the heat resistance of the considered coatings on the method of their application and phase-structural state is established. Especially valuable is the established mechanism of formation and propagation of thermal fatigue cracks depending on the phase composition of the initial coating. It is shown that the durability of protective coatings with cyclic temperature change depends on the chemical composition of the coating and the method of its formation. The dependence of the formation of thermal fatigue cracks on the samples with the coatings under study on the number of cycles of temperature change is established.

scholarly journals Vacuum-plasma multilayer protective coatings for turbine blades

2021 ◽  
Author(s):  
Alex Sagalovych ◽  
Vlad Sagalovych ◽  
Victor Popov ◽  
Stas Dudnik
Keyword(s):  
Protective Coatings ◽  
Turbine Blades ◽  
Vacuum Plasma
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