Repairing of Degraded Hot Section Parts of Gas Turbines by Cold Spraying

2009 ◽  
Vol 417-418 ◽  
pp. 545-548 ◽  
Author(s):  
Kazuhiro Ogawa ◽  
Takahiro Niki
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Cold Spraying ◽  
Combined Cycle ◽  
No Oxidation ◽  
Maintenance Cost ◽  
Temperature Oxidation ◽  
Gas Turbine Blades

Hot section parts of combined cycle gas turbines are susceptible to degradation due to high temperature creep, crack formation by thermal stress, and high temperature oxidation, etc. Thus, regularly repairing or replacing the hot section parts such as gas turbine blades is inevitable. For this purpose, revolutionary and advanced repair technologies for gas turbines have been developed to enhance reliability of the repaired parts and reduce the maintenance cost of the gas turbines. The cold spraying process, which has been studied as not only a new coating technology but also as a process for obtaining a thick deposition layer, is proposed as a potential repairing solution. The process results in little or no oxidation of the spray materials, so the surfaces stay clean, which in turn enables superior bonding. Since the operating temperature is relatively low, the particles do not melt and the shrinkage on cooling is very low. In this study, the cold spraying conditions were optimized by taking into account the particle kinetic energy and the rebound energy for application in repairing gas turbine blades. A high quality cold-sprayed layer is that which has lowest porosity; thus the spraying parameters were optimized to achieve low-porosity layer, which was verified by scanning electron microscopy (SEM).

High Temperature Degradation of Coating and Substrate in Gas Turbine Blade

1995 ◽  
Author(s):  
Y. Sugita ◽  
M. Ito ◽  
N. Isobe ◽  
S. Sakurai ◽  
C. R. Gold ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Cross Sections ◽  
Turbine Blades ◽  
Temperature Oxidation ◽  
Gas Turbine Blades ◽  
Coating Surface ◽  
Ductile Brittle Transition Temperature ◽  
Scanning Auger Microprobe ◽  
Long Time

This paper studied high temperature degradation behavior of gas turbine blades consisting of CoNiCrAlY coatings and Rene 80 substrates using a small punch (SP) testing technique at 295–1223 K and scanning Auger microprobe (SAM). In SP tests, coating cracks continuously propagated along the radial direction at 295 K and many cracks discretely were formed along more random directions at higher temperatures. The ductility of the coating at 295 K was reduced and the ductile-brittle transition temperature was increased during long time exposure of gas turbine blades to high temperature oxidation environments. SAM analyses on cross sections and fracture surfaces of the coatings indicated that oxidation and S segregation near the coating surface are profoundly induced in-service. The relationship between the mechanical properties and microstructural/chemical evolution near the coating surface is presented which serves as a data base for determining the remaining life of gas turbine blades.

scholarly journals Transpiration Air Protected Turbine Blades: An Effective Concept to Achieve High Temperature and Erosion Resistance for Gas Turbines Operating in an Aggressive Environment

1978 ◽  
Author(s):  
R. Raj ◽  
S. L. Moskowitz
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Erosion Resistance ◽  
Turbine Blades ◽  
Future Generation ◽  
Combined Cycle ◽  
Gaseous Fuels ◽  
Cooled Blade

The future generation is looking forward to the use of gas turbine inlet temperatures as high as 3000 F (1650 C) with attendant thermal efficiencies of from 40 to 50 percent in combined cycle electric power plants. In addition to the use of high temperature for improved efficiency, the national needs, due to scarcity of oil and natural gas, will heavily stress the use of coal as a fuel. The particulate from combustion of coal derived liquid and gaseous fuels, even after employing hot gas cleanup systems, may damage conventional turbine blades and thus reduce turbine life. This paper is intended to show how a transpiration-cooled blade can cope with both of the foregoing problems simultaneously. The fundamental aspects of the transpiration-cooled blade technology will also be explained. Experimental results using this design concept indicate that significant erosion resistance is feasible for gas turbine blading in the near future.

Finite Element Modeling of the Eddy-Current Inspection of Land-Based Gas Turbine Blades

2001 ◽  
Author(s):  
Hiroyuki Fukutomi ◽  
Takashi Ogata
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Gas Turbine ◽  
Eddy Current ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Multiple Cracks ◽  
Gas Turbine Blades ◽  
Element Modeling

There has been a growing need in recent technology of gas turbines in combined cycle to assess the remaining life of high temperature components. It is also required that the nondestructive assessment be more accurate in maintaining combined cycle plants. This paper describes the use of a simulator solving forward and inverse problems under eddy current testing, in parametric studies of inspection parameters for 1100°C-class gas turbine blades in terms of test probe capabilities, frequencies and signal interpretation. The simulator is based on a differential formulation constructed with a magnetic vector potential and a 3-dimensional edge-based finite-element modeling method. Its features are forming coils and defects independent of a whole finite element model, very fast eddy current response predictions, and identifications of electromagnetic properties. Using the simulator, optimal sensor types and test frequencies are determined in terms of assessment of degradation, selectability between surface-breaking and subsurface cracks, reconstruction of crack profiles, and detection of multiple cracks.

The High Temperature Turbo-jet Engine

1956 ◽  
Vol 60 (549) ◽  
pp. 563-589 ◽  
Author(s):  
D. G. Ainley
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Axial Flow ◽  
Jet Engine ◽  
Gas Turbine Blades ◽  
Turbine Design ◽  
The University ◽  
Transfer Problems

The 985th Lecture to be given before the Society, “ The High Temperature Turbo-jet Engine ” by D. G. Ainley, B.Sc, A.M.I.Mech.E., A.F.R.Ae.S., was given at the Institution of Civil Engineers, Great George St., London, S.W.I on 15th March 1956, with Mr. N. E. Rowe, C.B.E., D.I.C., F.C.G.I., F.I.A.S., F.R.Ae.S., in the Chair. Introducing the Lecturer, Mr. Rowe said that Mr. Ainley had been working on gas turbines since 1943 when he joined the gas turbine division of the Royal Aircraft Establishment. He transferred to Power Jets Ltd. and later to the National Gas Turbine Establishment. His early work was associated with the development of axial flow compressors, contraction design and so on; he then transferred to turbine design, became head of the section dealing with turbine and heat transfer problems and for the past five or six years had been chiefly engaged on the cooling of gas turbine blades. Mr. Ainley graduated from the University of London, Queen Mary College, with first class honours. In 1953 he was awarded the George Stephenson Research Prize by the Institution of Mechanical Engineers.

UDIMET L-605

Alloy Digest ◽  
2004 ◽  
Vol 53 (12) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Gas Turbine ◽  
Oxidation Resistance ◽  
Turbine Blades ◽  
Heat Treating ◽  
Gas Turbine Blades ◽  
Temperature Performance

Abstract Udimet L-605 is a high-temperature aerospace alloy with excellent strength and oxidation resistance. It is used in applications such as gas turbine blades and combustion area parts. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: CO-109. Producer or source: Special Metals Corporation.

Development and Fabrication of Silicon Nitride Components for Ceramic Gas Turbine

1997 ◽  
Author(s):  
Keisuke Makino ◽  
Ken-Ichi Mizuno ◽  
Toru Shimamori
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
High Strength ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Spark Plug ◽  
Power Turbine

NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles. In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1,350 °C in accordance with the project goals, we developed two silicon nitride materials with further unproved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles. In this paper, we report on the properties of these materials, and present the results of evaluations of these materials when they are actually used for CGT components such as first stage turbine blades and power turbine nozzles.

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