scholarly journals Electron Microscopy Characterization of the High Temperature Degradation of the Aluminide Layer on Turbine Blades Made of a Nickel Superalloy

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3240
Author(s):  
Mariusz Bogdan ◽  
Witold Zieliński ◽  
Tomasz Płociński ◽  
Krzysztof Jan Kurzydłowski
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Turbine Blades ◽  
Nickel Superalloy ◽  
Rotor Blades ◽  
Jet Engines ◽  
Destructive Testing ◽  
Alumina Layer ◽  
Microscopy Characterization ◽  
Aluminide Layer

The effects of exposure to overheating (temperature above 1000 °C) on the degradation (modification) of layers of coatings (coatings based on aluminum) of uncooled polycrystalline rotor blades of aircraft turbine jet engines were investigated under laboratory conditions. In order to determine the nature of the changes as well as the structural changes in the various zones, a multi-factor analysis of the layers of the coating, including the observation of the surface of the blades, using, among others, electron microscopy, structural tests, surface morphology, and chemical composition testing, was carried out. As a result of the possibility of strengthening the physical foundations of the non-destructive testing of blades, the undertaken research mainly focused on the characteristics of the changes occurring in the outermost layers of the coatings. The obtained results indicate the structural degradation of the coatings, particularly the unfavorable changes, become visible after heating to 1050 °C. The main, strongly interacting, negative phenomena include pore formation, external diffusion of Fe and Cr to the surface, and the formation and subsequent thickening of Fe-Cr particles on the surface of the alumina layer.

scholarly journals A Novel Method for High Temperature Fatigue Testing of Nickel Superalloy Turbine Blades with Additional NDT Diagnostics

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1392
Author(s):  
Dominik Kukla ◽  
Mateusz Kopec ◽  
Ryszard Sitek ◽  
Aleksander Olejnik ◽  
Stanisław Kachel ◽  
...  
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Fatigue Testing ◽  
Turbine Blades ◽  
Nickel Superalloy ◽  
Fe Model ◽  
Destructive Testing ◽  
High Temperature Fatigue ◽  
Bending Load ◽  
Novel Method

In this paper, a novel method for high temperature fatigue strength assessment of nickel superalloy turbine blades after operation at different times (303 and 473 h) was presented. The studies included destructive testing (fatigue testing at temperature 950 °C under cyclic bending load), non-destructive testing (Fluorescent Penetrant Inspection and Eddy Current method), and finite element modelling. High temperature fatigue tests were performed within load range from 5200 to 6600 N using a special self-designed blade grip attached to the conventional testing machine. The experimental results were compared with the finite element model generated from the ANSYS software. It was found that failure of turbine blades occurred in the area with the highest stress concertation, which was accurately predicted by the finite element (FE) model.

scholarly journals Experimental Evaluation of the Effects of Structural Changes on the Vibration Properties of CK35 Steel

2021 ◽  
Vol 15 (2) ◽  
pp. 53-57
Author(s):  
Navid Moshtaghi Yazani
Keyword(s):  
Power Plants ◽  
Structural Changes ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Damping Coefficient ◽  
Jet Engines ◽  
Modal Test ◽  
Long Run ◽  
Ferrite Structure ◽  
Non Destructive

Abstract The microstructure of some components which operate in high-temperature conditions (e.g. boiler components, turbine blades used in gas power plants, jet engines and reactors) is subjected to changes in long run, which leads to a degradation in the mechanical properties of these components and consequently, reduces their lifecycle. Therefore, it is so useful to detect the changes in the microstructure of these parts during their operation, employing an easy, fast and non-destructive method to determine their remaining life. In this study, we evaluate the effects of the microstructural changes on natural frequencies and the damping coefficient of CK35 steel, employing the experimental modal test. We aim to use the method for power plant components, if it has significant effects. To do so, we applied spheroidization heat treatment on CK35 steel samples having a primary structure of ferrite-pearlite for 24 and 48 hours. Then, we carried out the experimental modal test on samples having different metallurgical structures, but with the same dimensions and weights. According to the findings, the spherical ferrite-carbide particles in the ferrite structure increase the natural frequencies and damping coefficient. These tests show that the structural changes in this type of steel result in slight changes in the values of natural frequencies; however, it significantly changes the damping frequencies.

Combination of optical metrology and non-destructive testing technology for the regeneration of aero engine components

2021 ◽  
Vol 88 (4) ◽  
pp. 237-250
Author(s):  
Nils Melchert ◽  
Maximilian K.-B. Weiss ◽  
Tim Betker ◽  
Wojciech Frackowiak ◽  
Renè Gansel ◽  
...  
Keyword(s):  
Turbine Blades ◽  
Regeneration Process ◽  
Detailed Knowledge ◽  
Jet Engines ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Before And After ◽  
Testing Technology ◽  
Engine Components ◽  
Non Destructive

Abstract The maintenance and repair of jet or gas turbine components has a considerably high share in the overall turbine operating costs. The authors deal with the regeneration process of complex capital goods considering jet engines as an example, with turbine blades being the most important components to be regenerated. In order to decide on a reasonable and economical regeneration path, maintenance approaches typically require detailed knowledge of the shape and wear condition of the components. In order to select suitable repair strategies for each component, the best possible knowledge about geometry, damages and surface topologies is necessary. In order to meet these requirements, a novel combination of non-destructive testing and measuring methods will be presented. Each process can be adapted for inline operation. The presented methods also enable quality control of the regenerated components that have completed their individual regeneration path. Due to the high variety of possible defects on turbine blades, the individually presented methods can be combined to form an inspection sequence. Detailed status monitoring before and after maintenance becomes possible for each component. This provides the basis for further decisions in the regeneration process.

Aerodynamic Excitation Analysis for Variable Tip Gap

2016 ◽  
Author(s):  
Thomas Hauptmann ◽  
Joerg R. Seume
Keyword(s):  
Experimental Data ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Spare Parts ◽  
Rotor Blades ◽  
Jet Engines ◽  
Flow Conditions ◽  
Reference Case ◽  
Structure Interaction ◽  
Blade Repair

In jet engines, blade repair is often more economical than the replacement of damaged blades with spare parts. Besides such regeneration of turbine blades, blade rubbing and erosion lead to a deviation of the geometry in the tip region of the original blade. These geometric variations can introduce non-uniform flow conditions which in turn may lead to an excitation of the blades. An analysis of the aerodynamic excitation due to typical geometric variations of the radial tip gap, introduced through substantial wear, is numerically investigated using a fluid-structure interaction (FSI) approach. The model was previously validated against experimental data. The results of the analysis show up to 1.6 times higher excitation than in the reference case, because rotor blades are excited by the wakes of the stator vanes and are amplified by a modified tip flow in the rotor passage.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

Conformational characterization of nucleosome structure by Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 194-195
Author(s):  
Gregory J. Czarnota
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Physiological State ◽  
Gene Activation ◽  
Three Dimensional ◽  
Macromolecular Complex ◽  
Ultrastructural Studies ◽  
Ionic Environment ◽  
Nucleosome Structure ◽  
Dimensional Reconstruction

Chromatin structure at the fundamental level of the nucleosome is important in vital cellular processes. Recent biochemical and genetic analyses show that nucleosome structure and structural changes are very active participants in gene expression, facilitating or inhibiting transcription and reflecting the physiological state of the cell. Structural states and transitions for this macromolecular complex, composed of DNA wound about a heterotypic octamer of variously modified histone proteins, have been measured by physico-chemical techniques and by enzyme-accessibility and are recognized to occur with various post-translational modifications, gene activation, transformation and with ionic-environment. In spite of studies which indicate various forms of nucleosome structure, all current x-ray and neutron diffraction studies have consistently resulted in only one structure, suggestive of a static conformation. In contrast, two-dimensional electron microscopy studies and three-dimensional reconstruction techniques have yielded different structures. These fundamental differences between EM and other ultrastructural studies have created a long standing quandary, which I have addressed and resolved using spectroscopic electron microscopy and statistical analyses of nucleosome images in a study of nucleosome structure with ionic environment.

A Transmission Electron Microscopical Investigation of Phase Transformations in TiNi

1980 ◽  
Vol 38 ◽  
pp. 340-341
Author(s):  
P. Moine ◽  
G. M. Michal ◽  
R. Sinclair
Keyword(s):  
Electron Microscopy ◽  
Phase Transformations ◽  
Applied Stress ◽  
Structural Changes ◽  
Microscopical Investigation ◽  
Temperature Range ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Diffraction Effects ◽  
Microscopy Images

Premartensitic effects in near equiatomic TiNi have been pointed out by several authors(1-5). These include anomalous contrast in electron microscopy images (mottling, striations, etc. ),diffraction effects(diffuse streaks, extra reflections, etc.), a resistivity peak above Ms (temperature at which a perceptible amount of martensite is formed without applied stress). However the structural changes occuring in this temperature range are not well understood. The purpose of this study is to clarify these phenomena.

Structural Studies of Fibrinolysis by Electron and Light Microscopy

1999 ◽  
Vol 82 (08) ◽  
pp. 277-282 ◽  
Author(s):  
Yuri Veklich ◽  
Jean-Philippe Collet ◽  
Charles Francis ◽  
John W. Weisel
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Plasminogen Activator ◽  
Structural Changes ◽  
Molecular Mechanisms ◽  
Degradation Products ◽  
Molecular Model ◽  
Three Dimensional ◽  
Tissue Type ◽  
Type Plasminogen Activator

IntroductionMuch is known about the fibrinolytic system that converts fibrin-bound plasminogen to the active protease, plasmin, using plasminogen activators, such as tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator. Plasmin then cleaves fibrin at specific sites and generates soluble fragments, many of which have been characterized, providing the basis for a molecular model of the polypeptide chain degradation.1-3 Soluble degradation products of fibrin have also been characterized by transmission electron microscopy, yielding a model for their structure.4 Moreover, high resolution, three-dimensional structures of certain fibrinogen fragments has provided a wealth of information that may be useful in understanding how various proteins bind to fibrin and the overall process of fibrinolysis (Doolittle, this volume).5,6 Both the rate of fibrinolysis and the structures of soluble derivatives are determined in part by the fibrin network structure itself. Furthermore, the activation of plasminogen by t-PA is accelerated by the conversion of fibrinogen to fibrin, and this reaction is also affected by the structure of the fibrin. For example, clots made of thin fibers have a decreased rate of conversion of plasminogen to plasmin by t-PA, and they generally are lysed more slowly than clots composed of thick fibers.7-9 Under other conditions, however, clots made of thin fibers may be lysed more rapidly.10 In addition, fibrin clots composed of abnormally thin fibers formed from certain dysfibrinogens display decreased plasminogen binding and a lower rate of fibrinolysis.11-13 Therefore, our increasing knowledge of various dysfibrinogenemias will aid our understanding of mechanisms of fibrinolysis (Matsuda, this volume).14,15 To account for these diverse observations and more fully understand the molecular basis of fibrinolysis, more knowledge of the physical changes in the fibrin matrix that precede solubilization is required. In this report, we summarize recent experiments utilizing transmission and scanning electron microscopy and confocal light microscopy to provide information about the structural changes occurring in polymerized fibrin during fibrinolysis. Many of the results of these experiments were unexpected and suggest some aspects of potential molecular mechanisms of fibrinolysis, which will also be described here.

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