Microstructures and compositions of oxide films formed on CoCrAlY and Y-ion-implanted CoCrAl alloys

1983 ◽  
Vol 41 ◽  
pp. 216-217
Author(s):  
J. A Sprague ◽  
G. R. Johnston
Keyword(s):  
Elevated Temperatures ◽  
Surface Composition ◽  
Cast Alloy ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Protective Oxide ◽  
Protection Scheme ◽  
Temperature Exposure ◽  
Overlay Coatings ◽  
Slow Growing

Hot stage components in many gas turbine engines require surface coatings to protect them from aggressive atmospheres at elevated temperatures. The most commonly employed protection scheme is to modify the surface composition of the components so that high temperature exposure in an oxidizing atmosphere will produce a dense, slow-growing, and adherent aluminum and/or chromium oxide film. Alloys of the MCrAlX-type, where M = Co, Ni, Fe, or combinations thereof, and X = a highly oxygen-active element such as Y, Hf, or Ce, are widely employed as overlay coatings in these applications. In the present investigation, several microanalytical techniques were applied to examine the mechanisms by which the microstructure and microchemistry of a CoCrAlY coating alloy affects the growth and adherence of protective oxide scales.Two cast alloy compositions were examined: Co-22Cr-llAl, and Co-22Cr-l1A1- 0.5Y (nominal compositions, wt. %). Selected specimens of the CoCrAl alloy were implanted with 2 × 1016 Y+/cm2 or 5 × 1016 Co+/cm2 at 150 keV.

Engine Test Experience and Characterization of Self Sealing Ceramic Matrix Composites for Nozzle Applications in Gas Turbine Engines

2003 ◽  
Author(s):  
Eric P. Bouillon ◽  
Patrick C. Spriet ◽  
Georges Habarou ◽  
Thibault Arnold ◽  
Greg C. Ojard ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Turbine Engines ◽  
Matrix Composites ◽  
Gas Turbine Engines ◽  
Sic Fiber ◽  
Engine Testing

Advanced materials are targeting durability improvement in gas turbine engines. One general area of concern for durability is in the hot section components of the engine. Ceramic matrix composites offer improvements in durability at elevated temperatures with a corresponding reduction in weight for nozzles of gas turbine engines. Building on past material efforts, ceramic matrix composites using a carbon and a SiC fiber with a self-sealing matrix have been developed for gas turbine applications. Prior to ground engine testing, a reduced test matrix was undertaken to aggressively test the material in a long-term hold cycle at elevated temperatures and environments. This tensile low cycle fatigue testing was done in air and a 90% steam environment. After completion of the aggressive testing effort, six nozzle seals were fabricated and installed in an F100-PW-229 engine for accelerated mission testing. The C fiber CMC and the SiC Fiber CMC were respectively tested to 600 and 1000 hours in accelerated conditions without damage. Engine testing is continuing to gain additional time and insight with the objective of pursuing the next phase of field service evaluation. Mechanical testing and post-test characterization results of this testing will be presented. The results of the engine testing will be shown and overall conclusions drawn.

Future Research Directions for Ship Propulsion Materials

2009 ◽  
Author(s):  
David A. Shifler
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Fuel Efficiency ◽  
High Strength ◽  
Turbine Engines ◽  
Future Research ◽  
Oxide Surface ◽  
Materials Testing ◽  
Gas Turbine Engines ◽  
Protective Oxide

High temperature applications demand materials that have a variety of properties such as high strength, toughness, creep resistance, fatigue resistance, as well as resistance to degradation by their interaction with the environment. All potential metallic materials are unstable in many high temperatures environments without the presence of a protective coating on the component surface. High temperature alloys derive their resistance to degradation by forming and maintaining a continuous protective oxide surface layer that is slow-growing, very stable, and adherent. In aggressive environments, the superalloy oxidation and corrosion resistance needs to be augmented by coatings. Propulsion materials for Naval shipboard gas turbine engines are subjected to the corrosive environment of the sea to differing degrees. Increasing fuel efficiency and platform capabilities require higher operating temperatures that may lead to new degradation modes of coatings and materials. Fuel contaminants or the lack of contaminants from alternative synthetic fuels may also strongly influence coating and/or materials performance which, in turn, can adversely affect the life in these propulsion or auxiliary gas turbine engines. This paper will dwell on some past results of materials testing and offer some views on future directions into materials research in high temperature materials in aggressive environments that will lead to new advanced propulsion materials for shipboard applications.

scholarly journals Thermal Strains and Their Effect on the Life of Ceramic Matrix Composite Components in Gas Turbine Engines

1996 ◽  
Author(s):  
Michael J. L. Percival ◽  
Colin P. Beesley
Keyword(s):  
Gas Turbine ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Component Design ◽  
Design Stress

Currently available Ceramic Matrix Composites (CMCs) have very low stress carrying capability if they are to achieve the service life required for application in gas turbine engines. As such, they are most likely to find their first applications in non-structural components with low mechanical loads, where the majority of the stress is thermally induced. The thermal cycling experienced in gas turbine engines, coupled with the necessary interfaces with surrounding metal components and other geometric features, means that these thermal stresses are often localised, but in order to produce a valid component design they may significantly exceed the maximum design stress. The aim of this paper is to discuss the implications for the life of the component of these excess stresses. This will cover the mechanisms for the propagation of localised damage in a strain controlled environment, and the effect of this damage on the thermal conductivity and hence on the induced thermal gradients and thermal strains. Strains corresponding to stresses considerably above the normally accepted design stress can be sustained for a considerable number of cycles, but the influence of extended time periods with damage at elevated temperatures remains unexplored.

Microvoid formation in the grain boundary phase of a sintered Si-Al-O-N ceramic after static fatigue testing

1986 ◽  
Vol 44 ◽  
pp. 490-491
Author(s):  
M. R. Hughes ◽  
T. A. Nolan ◽  
J. Chang
Keyword(s):  
Silicon Nitride ◽  
Elevated Temperatures ◽  
Fatigue Testing ◽  
Slow Crack Growth ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Static Fatigue ◽  
Gas Turbine Engines ◽  
Sintering Aid ◽  
Intergranular Phase

Sintered silicon nitride materials are currently being considered for use in hot flow-path components of gas turbine engines because of their good thermal shock and oxidation resistance as well as strength at high temperatures. These materials, however, have been shown to be susceptible to slow crack growth (SCG) and creep at elevated temperatures. The high-temperature properties are largely determined by the intergranular phase which is composed of the sintering aid residue and may be either amorphous or crystalline depending on sintering and annealing parameters. The silicon nitride examined in this study had reportedly been sintered with Y2O3 (5.86%) and Al2O3 (2.2%) to produce a composite of β'Si3N4 crystals in an amorphous Y-Si-Al-O-N matrix. Static fatique tests performed on test bars of this material resulted in failures originating, via SCG and creep within the intergranular phase, above certain stress loads at 1000°C. These sites and other areas through the cross section of the test bars were examined by SEM and AEM to determine the microstructure and chemistry related to these failure phenomena.

Alloy Selection for Honeycomb Gas Path Seal Systems

2004 ◽  
Author(s):  
Dieter R. Sporer ◽  
Lawrence T. Shiembob
Keyword(s):  
Elevated Temperatures ◽  
Thin Foil ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Test Conditions ◽  
Gas Corrosion ◽  
Selection For ◽  
Microstructural Integrity

Metallic honeycombs are widely used in gas turbine engines as inner and outer abradable gas path seals. The ever increasing gas temperatures encountered in the high and low pressure turbine modules of modern engine designs challenge the durability of the thin foil metals used to fabricate seal type honeycomb. In this paper the performance of a number of alloys in turbine seal applications is reviewed. Emphasis is placed on resistance to hot gas corrosion attack and microstructural integrity after exposure to elevated temperatures. The abradability of fabricated seal structures under two distinctly different rub test conditions is reviewed. Among the alloys considered, the Fe-Cr-Al-Y alloy MI 2100 offers a potentially superior combination of oxidation resistance, abradability, fabricability and material cost for seal honeycomb applications.

scholarly journals Elevated Temperature Exposure of Gas Turbine Materials to a Bio-Fuel Combustion Environment

1998 ◽  
Author(s):  
P. C. Patnaik ◽  
C. Adams ◽  
D. Fuleki ◽  
R. Thamburaj
Keyword(s):  
Gas Turbine ◽  
Hot Corrosion ◽  
Combustion Products ◽  
Fuel Combustion ◽  
Turbine Engines ◽  
Type I ◽  
Gas Turbine Engines ◽  
Material Systems ◽  
Temperature Exposure ◽  
High Alkali

The use of biomass fuels in gas turbine engines requires an examination of the effect of the fuel on the engine materials. While the fuel may be more environmentally friendly than conventional fuels, it has the potential to produce serious life limiting corrosion within gas turbine engines. The effects of the high alkali and low sulphur content of the fuel on its corrosive properties needs to be examined. To determine the extent and type of corrosion typical material systems were exposed to bio-fuel combustion products in a flame tunnel and furnace under conditions designed to promote high temperature corrosion. The preliminary results indicate that type I hot corrosion is certainly occurring with some signs of type II hot corrosion in certain material systems.

scholarly journals РАСЧЕТНО-ЭКСПЕРИМЕНТАЛЬНАЯ МЕТОДИКА ОПРЕДЕЛЕНИЯ ДИНАМИЧЕСКОГО МОДУЛЯ УПРУГОСТИ ПРИРАБАТЫВАЕМЫХ УПЛОТНИТЕЛЬНЫХ ПОКРЫТИЙ ТУРБИН ГТД

2019 ◽  
pp. 105-113
Author(s):  
Виктор Леонидович Грешта ◽  
Дмитрий Викторович Павленко ◽  
Ярослав Викторович Двирнык ◽  
Дарья Владимировна Ткач
Keyword(s):  
Elastic Modulus ◽  
Numerical Experiment ◽  
Gas Turbine ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Elevated Temperatures ◽  
Coated Sample ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Dynamic Modulus Of Elasticity

The aim of the work was the development and testing of a method for determining the dynamic modulus of elasticity of running-in sealing gasket coatings for GTE turbines. Many contradictory requirements are put forward to these coatings, therefore, to satisfy them, it was proposed to apply coatings with variable properties at various stages of the life cycle of gas turbine engines. However, the development of new coatings requires a variety of mechanical tests, including to evaluate the dynamic modulus of elasticity. The porous structure and, accordingly, the low strength of the developed coatings do not allow the use of standard methods for the evaluation of mechanical properties, so there is a need to develop a special method for determining the elastic modulus. In the course of the study, the finite element method, statistical methods, experimental methods for determining the natural frequency of oscillations were applied. Investigations were carried out for running-in sealing coating of the stator of turbines of gas turbine engines KNA-82 + CoNiCrAlY. The numerical experiment was performed in the Ansys Work-bench 2019 R2 software package. Since coatings are used at elevated temperatures, it was necessary to estimate the modulus of elasticity at various temperatures, which required additional studies of temperature-dependent properties that affect the desired value. As a result of the implementation of the plan of a numerical experiment to determine the frequency of natural oscillations of samples with a coating while varying its elastic modulus and temperature, as well as solving the inverse problem of establishing the dependence of the dynamic elastic modulus on the natural oscillation frequency of a coated sample, we developed a calculation and experimental method for determining the dynamic modulus elasticity of running-in sealing coatings of GTE turbines. The developed technique is used to determine the dynamic modulus of elasticity of running-in coatings of different chemical composition and structure in the range of operating temperatures, which can be used to optimize their composition, structure, and properties.

State-of-Art Technology ALLVAC 718 Plus Superalloy for Gas Turbine Engine Parts

2011 ◽  
Vol 213 ◽  
pp. 131-135 ◽  
Author(s):  
Sinem Cevik Uzgur ◽  
Yagiz Uzunonat ◽  
S. Fehmi Diltemiz ◽  
Melih Cemal Kushan ◽  
Rabia Gunay
Keyword(s):  
Gas Turbine ◽  
Elevated Temperatures ◽  
Low Cost ◽  
High Strength ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Turbine Engine ◽  
Materials Used ◽  
Corrosion And Oxidation ◽  
Aerospace And Defense

Innovations on the aerospace and aircraft industry have been throwing light upon building to future’s engineering architecture at the today’s globalization world where technology is the indispensable part of life. On the basis of aviation sector, the improvements of materials used in aircraft gas turbine engines which constitute 50 % of total aircraft weight must protect its actuality continuously. Utilization of super alloys in aerospace and defense industries can not be ignored because of excellent corrosion and oxidation resistance, high strength and long creep life at elevated temperatures. The newly innovated ALLVAC 718 Plus superalloy which is the last version of Inconel 718 has been proceeding in the way to become a material that aerospace and defense industries never replace of any other material with combining its good mechanical properties, easy machinability and low cost. However because it is a newly developed superalloy, in present paper its properties including chemistry, microstructure, strengthening mechanisms, weldability and cost will be discussed and the superiority of the ALLVAC 718 plus will be addressed.

Modeling Foreign Object Damage to CVI MI SiC/iBN/SiC and Oxide/Oxide Ceramic Composite Components in Gas Turbine Engines at Ambient and Elevated Temperatures

2011 ◽  
Author(s):  
Frank Abdi ◽  
HeeMann Yun ◽  
Cody Godines ◽  
Gregory Morscher
Keyword(s):  
Gas Turbine ◽  
Test Data ◽  
Elevated Temperatures ◽  
Full Range ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Turbine Engines ◽  
Oxide Ceramic ◽  
Gas Turbine Engines ◽  
Macro Scale

The inherent toughness of ceramic matrix composites (CMCs) in advanced gas-turbine engines must be predictable under impact from small foreign objects to lower the amount of full scale testing needed to produce robust designs. Fiber/matrix/architecture properties of the composites, and a damage evolution based progressive failure code that can be used for a full range of composite architectures (GENOA) coupled with an explicit FEM impact code (LS-DYNA) were used to simulate impact and residual 4pt flexural strength of the ceramic engine components. This approach uses physics-based mechanics coupled at the micro and macro scale boundaries. The benefit of this technique is that the root cause of damage advancement at the micromechanical level could be understood and simulations could be performed to assess better damage tolerance structures. Steel projectiles with a diameter of 1.59 mm were used to impact the composites at speeds from 100–400 m/s (Mach 0.3–1.2) and the results shown to compare to prior test data for 2-D 5H Sylramic iBN CVI MI SiC at 25°C and 1316°C and for 2-D 8H N720/AS ceramic composites at 25°C. Simulations also gave insight to the micromechanical damage progression and were comparable with test data.

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