Deformation and Fracture Behaviors in the Freestanding APS-TBC - Effects of Process Parameters and Thermal Exposure

2007 ◽  
Vol 353-358 ◽  
pp. 1935-1938 ◽  
Author(s):  
Yasuhiro Yamazaki ◽  
T. Kinebuchi ◽  
H. Fukanuma ◽  
N. Ohno ◽  
K. Kaise
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Gas Turbines ◽  
Thermal Exposure ◽  
Substrate Material ◽  
Process Variables ◽  
Microstructural Investigation ◽  
Deformation And Fracture ◽  
Industrial Gas Turbines ◽  
Tbc Systems

Thermal barrier coatings (TBCs), that reduce the temperature in the underlying substrate material, are an essential requirement for the hot section components of industrial gas turbines. Recently, in order to take full advantage of the potential of the TBC systems, experimental and analytical investigations in TBC systems have been performed. However there is a little information on the deformation behavior of the top coating. In addition, the effects of the thermal exposure and the process parameters on the mechanical properties of the top coating have never been clarified. From these backgrounds, the effects of the process variables in APS and the thermal exposure on the mechanical properties were investigated in order to optimize the APS process of top coatings. The experimental results indicated that the mechanical properties of the APS-TBC, i.e. the tensile strength and the elastic modulus, were significantly changed by the process variables and the long term thermal exposure. The microstructural investigation was also carried out and the relationship between the mechanical properties and the porosity was discussed.

A Viscoplastic Modeling Approach for MCrAlY Protective Coatings for Gas Turbine Applications

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Roland Mücke
Keyword(s):  
Gas Turbines ◽  
Protective Coatings ◽  
Thermal Strain ◽  
Flow Characteristics ◽  
Strain Range ◽  
Substrate Material ◽  
Full Scale ◽  
Viscoplastic Material ◽  
Modeling Approach ◽  
Industrial Gas Turbines

MCrAlY coatings are applied in industrial gas turbines and aircraft engines to protect surfaces of hot gas exposed components from oxidation and corrosion at elevated temperature. Apart from oxidation resistance, coatings have to withstand cracking caused by cyclic deformation since coating cracks might propagate into the substrate material and thus limit the lifetime of the parts. In this context, the prediction of the coating maximum stress and the strain range during cyclic loading is important for the lifetime analysis of coated components. Analyzing the state of stress in the coating requires the application of viscoplastic material models. A coupled full-scale cyclic analysis of substrate and coating, however, is very expensive because of the different flow characteristics of both materials. Therefore, this paper proposes an uncoupled modeling approach, which consists of a full-scale cyclic analysis of the component without coating and a fast postprocessing procedure based on a node-by-node integration of the coating constitutive model. This paper presents different aspects of the coating viscoplastic behavior and their computational modeling. The uncoupled analysis is explained in detail and a validation of the procedure is addressed. Finally, the application of the uncoupled modeling approach to a coated turbine blade exposed to a complex engine start-up and shut-down procedure is shown. Throughout the paper bold symbols denote tensors and vectors, e.g., σ stands for the stress tensor with the components σij. The superscripts (.)S and (.)C symbolize the substrate and the coating, respectively, e.g., εthS stands for the tensor of substrate thermal strain. Further symbols are explained in the text.

scholarly journals Correlations between Process Parameters and Outcome Properties of Laser-Sintered Polyamide

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1850 ◽  
Author(s):  
Dan Ioan Stoia ◽  
Liviu Marşavina ◽  
Emanoil Linul
Keyword(s):  
Mechanical Properties ◽  
Energy Density ◽  
Process Parameters ◽  
Linear Trend ◽  
Selective Laser Sintering ◽  
Orientation Angle ◽  
Strength Properties ◽  
Process Variables ◽  
Sample Density ◽  
Dimensional Errors

As additive manufacturing (AM) becomes more accessible, correlating process parameters with geometric and mechanical properties is an important topic. Because the number of process variables in AM is large, extensive studies must be conducted in order to underline every particular influence. The study focuses on two variables—part orientation in the orthogonal horizontal plane and energy density—and targets two outcomes—geometric and tensile properties of the parts. The AM process was conducted on selective laser sintering (SLS) machine EOS Formiga P100 using EOS white powder polyamide (PA2200). After finishing the sinterization process, the parts were postprocessed, measured, weighted, and mechanically tested. The geometric evaluation and mass measurements of every sample allowed us to compute the density of all parts according to the sinterization energy and orientation, and to determine the relative error of every dimension. By conducting the tensile testing, the elastic and strength properties were determined according to process variables. A linear trend regarding sample density and energy density was identified. Also, large relative dimensional errors were recorded for the lowest energy density. Mechanical properties encountered the highest value for the highest energy density at a 45° orientation angle.

Effects of Thickness on Thermal and Mechanical Properties of Air-Plasma Sprayed Thermal Barrier Coatings

2010 ◽  
Vol 658 ◽  
pp. 372-375 ◽  
Author(s):  
Sang Yeop Lee ◽  
Jae Young Kwon ◽  
Tae Woong Kang ◽  
Yeon Gil Jung ◽  
Ung Yu Paik
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Exposure Time ◽  
Gas Turbines ◽  
Microstructural Analysis ◽  
Thermal Exposure ◽  
Thermal Barrier ◽  
Air Plasma

Thermal barrier coating systems (TBCs) prepared by an air-plasma spray (APS) have been used to protect metallic components of gas turbines because of its economic advantage. To enhance the energy efficiency of gas turbine systems, the operating temperature is increased to over 1300 °C, which requires a new material with low thermal conductivity and an increase of TBC thickness. In this study we have focused the microstructure related to the thickness of TBC and their thermal properties, with specific attention to defect species as well as to its morphology with the thermal exposure time. Resintering of TBC happens during thermal exposure in a high temperature, resulting in the less strain tolerance and the higher thermal conductivity. In order to investigate the thermal properties of TBC related to the microstructural evolution, TBCs with different thicknesses of 200 µm, 400 µm, 600 µm, and 2000 µm were deposited on a flat graphite by the APS. The thermal exposure tests were conducted in different dwell time till 800h at 1100 °C. The thermal diffusivity is significantly increased after thermal exposures, depending on the thermal exposure time. Microstructural analysis clearly shows that the variation of thermal diffusivity is ascribed to the coalescence of small cracks and the resintering effect. The hardness values of TBCs are also increased as well. The relationship between mechanical properties and TBC thickness is discussed, including the effect of thickness on thermal properties.

Degradation Characteristics of Inconel738LC with Thermal Exposure

2011 ◽  
Vol 275 ◽  
pp. 117-120
Author(s):  
Keun Bong Yoo ◽  
Han Sang Lee ◽  
Kyu So Song
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Stress Rupture ◽  
Thermal Exposure ◽  
High Temperature Strength ◽  
Material Degradation ◽  
Temperature Dependent ◽  
Microstructural Investigation ◽  
Combustion Gas ◽  
Hot Gas

Gas turbine components operated by hot combustion gas undergo material degradation due to the thermal cycle by daily startup and shutdown. The failure mechanism of the hot gas components is accompanied by degradation in the properties of high temperature strength and creep rupture time. Many hot gas components in gas turbines are made of Ni-based superalloy because of their high temperature performance. In this work, we survey the time and temperature dependent degradation of Ni-based superalloy. We prepared specimens from Inconel738LC that were then exposed at 871~982°C in 1,000~5,000hours. We carried out stress-rupture tests and microstructural investigation.

High Temperature Brazing for Cobalt-Based Gas Turbine Components

2000 ◽  
Author(s):  
Wayne Greaves ◽  
Hans van Esch
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Gas Turbine ◽  
Mechanical Testing ◽  
Gas Turbines ◽  
Cleaning Operation ◽  
Microstructural Evaluation ◽  
Industrial Gas Turbines ◽  
Crack Repair ◽  
The Common

A unique high temperature brazing process was developed for crack repair and surface restoration of cobalt superalloy components of industrial gas turbines. The repair method begins with a special cleaning operation consisting of both chemical and ultrahigh vacuum processes. A new high-temperature braze material, with a composition compatible with most of the common cobalt-based turbine alloys, was developed. The mechanical properties and weldability of the brazed material are comparable with those base alloys. Microstructural evaluation and mechanical testing confirmed the desired properties. Also, actual refurbishment applications of General Electric, Westinghouse, and ABB gas turbine components are shown.

CM 939 Weldable® Alloy

2004 ◽  
Author(s):  
Ken Harris ◽  
Jacqueline B. Wahl
Keyword(s):  
Mechanical Properties ◽  
Gas Turbines ◽  
Hot Tearing ◽  
Raw Material ◽  
Nickel Base Superalloy ◽  
Material Technology ◽  
Ultra High Purity ◽  
Industrial Gas Turbines ◽  
Nickel Base ◽  
Step Heat Treatment

IN 939 alloy, developed by the International Nickel Co. in the late 1960s, is a unique 22% Cr hot corrosion resistant γ′ strengthened, cast nickel-base superalloy. It is widely used in industrial gas turbines for equiaxed vanes, vane segments and burner nozzles and is of interest to the aero turbine industry for LP and PT integral nozzles (vane rings) and high temperature turbine casings. However, IN 939 is considered difficult to weld repair without parent metal microcracking and can exhibit marginal ductility in heavy section castings. Cannon-Muskegon has developed a proprietary chemistry modified version of IN 939 alloy designated CM 939 Weldable®. Emphasis has been directed on optimizing aim chemistry and ultra high purity manufacture using CM-developed single crystal superalloy melting and raw material technology and subsequently on obtaining superior casting microstructure for improved weldability and mechanical properties. Alloy purity and heat cleanliness will be discussed, along with a simplified two-step heat treatment cycle, resulting in attractive microstructure, mechanical properties and repair weldability. Significant market interest has resulted in extensive vacuum casting experience throughout the gas turbine industry. Excellent results in terms of fluidity, casting cleanliness and minimal microporosity have been obtained without any hot tearing or hot cracking problems.

Effect of processing variables on mechanical properties of montmorillonite clay/unsaturated polyester nanocomposite using Taguchi based grey relational analysis

2012 ◽  
Vol 32 (8-9) ◽  
pp. 555-566 ◽  
Author(s):  
Nagarajan Rajini ◽  
Jebas Thangaih Winowlin Jappes ◽  
Sivaprakasam Rajakarunakaran ◽  
Irullappasamy Siva
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Process Parameters ◽  
Grey Relational Analysis ◽  
Unsaturated Polyester ◽  
Optimum Process ◽  
Blade Design ◽  
Process Variables ◽  
Relational Analysis ◽  
Grey Relational

Abstract The present investigation addresses the influence of process variables on the mechanical properties of montmorillonite (MMT) nanoclay with unsaturated polyester, using the mechanical shear mixing process. The rotational speed, mixing time, rotor blade design and clay content were chosen as process variables. The influence of these process variables on mechanical properties were studied with the help of grey relational analysis. Organically modified MMT nanoclay was used as the reinforcing filler, in order to increase the swelling of the clay with the polyester resin. Nanocomposites were fabricated based on the experimental design using the L9 orthogonal array. Among the parameters studied, blade design was identified as the parameter with the most influence, due to the presence of a varying shear force, which peeled off the clay platelets from the stacked arrangement of clay tactoids. Grey relational analysis was used to obtain the optimum process parameters for multiple quality characteristics such as tensile, flexural and impact strength. It was observed that the Shore D hardness values for all nine experiments possess higher values than virgin polyester. Morphological studies have been carried out for the specimen with optimum process parameters using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile, flexural and impact fractured specimens were studied using scanning electron microscopy (SEM) for optimum conditions.

Mechanical Properties in GTD-111 Alloy in Heavy Frame Gas Turbines

2018 ◽  
Author(s):  
John R. Scheibel ◽  
Rajeev Aluru ◽  
Hans van Esch
Keyword(s):  
Mechanical Properties ◽  
Gas Turbines ◽  
Base Material ◽  
Partial Solution ◽  
Heat Treatments ◽  
Hot Gas ◽  
Operating Environments ◽  
Industrial Gas Turbines ◽  
Full Solution ◽  
Temperature Time

Nickel-based superalloys are extensively used in manufacturing hot gas path components in industrial gas turbines used for power generation. Specifically, GTD-111 DS is one of the widely used alloys used in manufacturing the hot gas path rotating components. These components are subjected to extreme operating environments resulting in creep, oxidation, and fatigue of the components during operation. After continued operation, these damage modes need to be repaired and the components go through extensive repair processes, which include several heat treatments to recover the mechanical properties of the base material (GTD-111 DS) lost during operation. The heat treatments used during repair by the different repair vendors can vary widely in terms of temperature, time and the sequence as well. This study focuses on understanding the differences in the effects of the heat treatments (partial solution, full solution, HIP and full solution) to the base material in terms of microstructure-mechanical property relationships. Results indicate that HIP and full solution resulted in refined microstructures and improved mechanical properties compared to the heat treatments involving partial solution or full solution only. Microstructuremechanical property relationships suggest that components that need to be repaired beyond OEM recommended repair intervals benefit from the HIP and full solution heat treatments.

A Viscoplastic Modeling Approach for MCrAlY Protective Coatings for Gas Turbine Applications

2008 ◽  
Author(s):  
Roland Mu¨cke
Keyword(s):  
Gas Turbines ◽  
Protective Coatings ◽  
Flow Characteristics ◽  
Strain Range ◽  
Substrate Material ◽  
Full Scale ◽  
Viscoplastic Material ◽  
Modeling Approach ◽  
Lifetime Analysis ◽  
Industrial Gas Turbines

MCrAlY coatings are applied in industrial gas turbines and aircraft engines to protect surfaces of hot gas exposed components from oxidation and corrosion at elevated temperature. Apart from oxidation resistance, coatings have to withstand cracking caused by cyclic deformation since coating cracks might propagate into the substrate material and thus limit the lifetime of the parts. In this context, the prediction of the coating maximum stress and strain range during cyclic loading is important for the lifetime analysis of coated components. Analyzing the state of stress in the coating requires the application of viscoplastic material models. A coupled full-scale cyclic analysis of substrate and coating, however, is very expensive because of the different flow characteristics of both materials. Therefore, this paper proposes an uncoupled modeling approach which consists of a full-scale cyclic analysis of the component without coating and a fast post-processing procedure based on a node-by-node integration of the coating constitutive model. This paper presents different aspects of the coating viscoplastic behavior and their computational modeling. The uncoupled analysis is explained in detail and a validation of the procedure is addressed. Finally, the application of the uncoupled modeling approach to a coated turbine blade exposed to a complex engine start-up and shut-down procedure is shown.

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