Thomas Duda | Dortmund University of Technology - Technische Universität Dortmund (original) (raw)

Papers by Thomas Duda

Oxidation Behavior of Electroplated MCrAlY Coatings

Thermal Spray 2003: Proceedings from the International Thermal Spray Conference

High temperature oxidation behavior of MCrAlY coatings was studied at several temperatures in the... more High temperature oxidation behavior of MCrAlY coatings was studied at several temperatures in the range from 800 to 1100°C. In this study the MCrAlY coatings were obtained by plating using CrAlY as precursor powders in an electrolytic bath containing nickel and cobalt salt in solution. The size of the precursor CrAlY powders used was generally below 10 um. As-plated coatings consisted of a random distribution of CrAlY particles in the Ni-Co matrix. The heat-treatment of the as-plated coatings at elevated temperature resulted in the development of a gamma and beta structure. Both as-deposited and oxidized coatings were characterized by optical, scanning electron microscope and electron beam microprobe. During oxidation the coatings formed alumina scale with a negligible amount of transient nickel and chromium oxides. The spallation resistance of the oxide scale was investigated by thermal shock testing. The test consisted of a rapid cooling from 1000°C to 100°C with a two- minute dwe...

Concept Optimization for Coating Application and Quality of APS Applied TBC on Gas Turbine Blades and Vanes

International Thermal Spray Conference

There are different concepts for TBC coating application that varies in the method of applying th... more There are different concepts for TBC coating application that varies in the method of applying the coating layers. An analysis of the existing part portfolio sprayed with different coating concepts shows that there is a 75 % difference in spray performance depending on which concept is used. This could lead to major savings regarding costs and time. This paper shows the effective use of offline programming tools in combination with a detailed coating process analysis. Based on this a time optimized coating concept for vanes and blades was developed. The validation of this optimized coating concept shows an improvement of more than 7 5 % in spray performance leading to a coating time improvement of up to 40%.

Manufacturing of Thick, Crack-Free Wear Protective Coatings on Complex Geometries for Gas Turbine Parts

International Thermal Spray Conference

This paper analyses the influence of specific coating parameters such as robot velocity, spray di... more This paper analyses the influence of specific coating parameters such as robot velocity, spray distance and part cooling on the risk of crack formation within Chromium- Carbide / Nickel-Chromium coatings. To understand the effect in more detail, metallographic investigations were conducted. These also provide sufficient data to examine other important coating characteristics such as porosity, mechanical stresses and homogeneity. As an additional analytical method Element Mapping is utilised to show the level of oxidation and its impact on the coating microstructure. The methods X-ray diffraction (XRD) and In-situ coating property (ICP)-Sensor are used to investigate the development of stresses in different coatings. With the information from all these examinations a concept was derived to achieve thick, crack-free wear protective coatings.

Title: An Evaluation of the Applicability of Lean Methods in an Engineer-to-Order, H igh-Mix-Low-... more Title: An Evaluation of the Applicability of Lean Methods in an Engineer-to-Order, H igh-Mix-Low-Volume Manufacturing Environment-A Case Study in the Heavy Industry The study reviewed the applicability of Lean methodology in the engineer-to-order, high-mix-low-volume environment. It asked the question of whether Lean practices find applicability in an engineer-to-order environment in the same way as in a mass production or in low-mix-high-volume environments. Furthermore, it looked to explore I V

Title: Ice dry stripping of TBC systems Authors

Thermal barrier coatings are gaining considerable importance for the improvement the energetic ef... more Thermal barrier coatings are gaining considerable importance for the improvement the energetic efficiency of turbines. These materials are often applied on the surface of blades and are based on a layer of antioxidation material (mainly MCrAlY alloys) and a top layer that acts as proper thermal barrier (normally Yttria partially stabilized Zirconia). Coating removal is an important aspect in the production of these blades. “Decoating” or “stripping” is needed for the production of new components as well as for the reconditioning of existing ones. The present paper is dedicated to a new method of removal of the Zirconia ceramic layer. The method is based on the ice dry removal of the ceramic layer. This method will not impact on the roughness and morphology of the bond coat surface, making it suitable for a further step of TBC coating, without any further operation. This possibility will impact on the stripping costs and time, saving all the operator related to the qualification of t...

3D Metal Printing Technology

IFAC-PapersOnLine, 2016

Abstract: 3D Printing or Additive manufacturing is a novel method of manufacturing parts directly... more Abstract: 3D Printing or Additive manufacturing is a novel method of manufacturing parts directly from digital model by using layer by layer material build-up approach. This tool-less manufacturing method can produce fully dense metallic parts in short time, with high precision. Features of additive manufacturing like freedom of part design, part complexity, light weighting, part consolidation and design for function are garnering particular interests in metal additive manufacturing for aerospace, oil & gas, marine and automobile applications. Powder bed fusion, in which each powder bed layer is selectively fused by using energy source like laser, is the most promising additive manufacturing technology that can be used for manufacturing small, low volume, complex metallic parts. This review presents overview of 3D Printing technologies, materials, applications, advantages, disadvantages, challenges, economics and applications of 3D metal printing technology.

Verfahren zum aufbringen einer schützenden beschichtung auf ein thermisch beanspruchtes bauteil

Productivity Increase by Using Multi-Tools for Coating of Turbine Parts

Method of depositing a local MCrAIY-coating

Method for application of a protective coating to a thermally-stressed component

Measuring Device for Measuring the Temperature of a Thermally Loaded Metallic Base Element, Provided with a Protective Surface Coating, and Method for Producing Such a Measuring Device

High-Speed Imaging and Sequence Analysis III, 2001

In the simplest terms possible, thermal spraying coating involves heating a material, in powder o... more In the simplest terms possible, thermal spraying coating involves heating a material, in powder or wire form, to a molten or semi-molten state. The material is propelled using a heat source, e.g. a very high temperature plasma flame to deposit it, creating a surface structure on a given substrate. The process is very complex because it depends on numerous parameters influencing each other. A necessary condition to improve process efficiency and quality of produced coatings is the determination of in-flight particle properties. The innovative Particle-Shape-Imaging (PSI) technique offers a new potential in particle diagnostics. It is intended for the analysis of size and shape of single particles within the plasma jet. The method is based on telemicroscopic imaging of the particle shades. A cw-laser beam is split into two beams of equal intensities, which are superimposed in the focal plane of a long-distance-microscope. The detection system consists of a CCD camera with a Micro- Channel-Plate intensifier allowing exposure times of a few nanoseconds. When a particle passes the measuring volume, the laser beams generate two individual shades. The position of the particle relatively to the focal plane is determined from the separation of the two shades in the image plane. From the evaluation of area and contour of the shades, particles can be classified in regard to size and form. Corresponding distributions of the particles within the plasma jet as well as changes of the particle form in the melting process can be determined.

Probabilistic Lifetime Prediction of Thermal Barrier Coating Systems Depending on Manufacturing Scatter

Volume 6: Ceramics; Controls, Diagnostics and Instrumentation; Education; Manufacturing Materials and Metallurgy, 2014

The assessment of Bondcoat/Thermal barrier coating systems is an inherent part of the lifing proc... more The assessment of Bondcoat/Thermal barrier coating systems is an inherent part of the lifing process of gas turbine component. On the one hand, coatings are considered in the constitutive modelling — e.g. in the thermal model and for the prediction of eigenfrequencies of gas turbine blades. On the other hand, the influence of the coating system on the lifetime of the part (target cyclic life and target operation hours) needs to be assessed. This paper addresses the prediction of coating lifetime. Lifing models of Bondcoat/Thermal barrier coating systems (BC/TBC) are commonly built using isothermal furnace cyclic tests (FCT). The lifetime of the BC/TBC under such test conditions has been shown to depend on multiple coating parameters like TBC thickness, TBC porosity, BC thickness, BC roughness, and also on testing temperature. For example, the TBC life (defined as time to partial TBC spallation) is reduced with increasing temperature, with increasing TBC thickness and decreasing poro...

Journal of Thermal Spray Technology, 2012

Over the last few years, global economic growth has triggered a dramatic increase in the demand f... more Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments. Keywords atmospheric plasma spray (APS), gas turbines, particle plasma interaction, residual stress determination, thermal barrier coatings (TBCs), torch design, yttria stabilized zirconia (YSZ) This article is an invited paper selected from presentations at the 2011 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously

Thermally Grown Oxides on Electroplated Bond Coats under APS TBC

Thermal Spray 2003: Proceedings from the International Thermal Spray Conference

MCrAlY bond coats were deposited on nickel base substrate by electroplated process. The bond coat... more MCrAlY bond coats were deposited on nickel base substrate by electroplated process. The bond coats were plated using ‘CrAlY’ precursor powders suspended in an electrolytic bath containing nickel and cobalt in solution. The CrAlY powders used had size in the range generally below 10 um. The as-deposited coatings were heat-treated in a vacuum at elevated temperature. The roughness of the as-deposited coatings was on the range from 2 to 4 um (average). Yttria stabilized zirconia thermal barrier coatings, 7YSZ were deposited by air plasma spray. The thickness of the both bond coats and TBCs was varied in order to determine the effects of thickness in the stability of the thermal barrier coatings. The coated samples were tested in a static furnace and also in a thermal shock test rig where the samples could be cooled rapidly from 1000°C to 100°C at a predetermined rate. The TGO formed at temperatures in the range from 800 to 1050°C was characterized by optical, scanning electron microsco...

Oxidation Behavior of Electroplated MCrAlY Coatings

Thermal Spray 2003: Proceedings from the International Thermal Spray Conference

High temperature oxidation behavior of MCrAlY coatings was studied at several temperatures in the... more High temperature oxidation behavior of MCrAlY coatings was studied at several temperatures in the range from 800 to 1100°C. In this study the MCrAlY coatings were obtained by plating using CrAlY as precursor powders in an electrolytic bath containing nickel and cobalt salt in solution. The size of the precursor CrAlY powders used was generally below 10 um. As-plated coatings consisted of a random distribution of CrAlY particles in the Ni-Co matrix. The heat-treatment of the as-plated coatings at elevated temperature resulted in the development of a gamma and beta structure. Both as-deposited and oxidized coatings were characterized by optical, scanning electron microscope and electron beam microprobe. During oxidation the coatings formed alumina scale with a negligible amount of transient nickel and chromium oxides. The spallation resistance of the oxide scale was investigated by thermal shock testing. The test consisted of a rapid cooling from 1000°C to 100°C with a two- minute dwe...

Concept Optimization for Coating Application and Quality of APS Applied TBC on Gas Turbine Blades and Vanes

International Thermal Spray Conference

There are different concepts for TBC coating application that varies in the method of applying th... more There are different concepts for TBC coating application that varies in the method of applying the coating layers. An analysis of the existing part portfolio sprayed with different coating concepts shows that there is a 75 % difference in spray performance depending on which concept is used. This could lead to major savings regarding costs and time. This paper shows the effective use of offline programming tools in combination with a detailed coating process analysis. Based on this a time optimized coating concept for vanes and blades was developed. The validation of this optimized coating concept shows an improvement of more than 7 5 % in spray performance leading to a coating time improvement of up to 40%.

Manufacturing of Thick, Crack-Free Wear Protective Coatings on Complex Geometries for Gas Turbine Parts

International Thermal Spray Conference

This paper analyses the influence of specific coating parameters such as robot velocity, spray di... more This paper analyses the influence of specific coating parameters such as robot velocity, spray distance and part cooling on the risk of crack formation within Chromium- Carbide / Nickel-Chromium coatings. To understand the effect in more detail, metallographic investigations were conducted. These also provide sufficient data to examine other important coating characteristics such as porosity, mechanical stresses and homogeneity. As an additional analytical method Element Mapping is utilised to show the level of oxidation and its impact on the coating microstructure. The methods X-ray diffraction (XRD) and In-situ coating property (ICP)-Sensor are used to investigate the development of stresses in different coatings. With the information from all these examinations a concept was derived to achieve thick, crack-free wear protective coatings.

Title: An Evaluation of the Applicability of Lean Methods in an Engineer-to-Order, H igh-Mix-Low-... more Title: An Evaluation of the Applicability of Lean Methods in an Engineer-to-Order, H igh-Mix-Low-Volume Manufacturing Environment-A Case Study in the Heavy Industry The study reviewed the applicability of Lean methodology in the engineer-to-order, high-mix-low-volume environment. It asked the question of whether Lean practices find applicability in an engineer-to-order environment in the same way as in a mass production or in low-mix-high-volume environments. Furthermore, it looked to explore I V

Title: Ice dry stripping of TBC systems Authors

Thermal barrier coatings are gaining considerable importance for the improvement the energetic ef... more Thermal barrier coatings are gaining considerable importance for the improvement the energetic efficiency of turbines. These materials are often applied on the surface of blades and are based on a layer of antioxidation material (mainly MCrAlY alloys) and a top layer that acts as proper thermal barrier (normally Yttria partially stabilized Zirconia). Coating removal is an important aspect in the production of these blades. “Decoating” or “stripping” is needed for the production of new components as well as for the reconditioning of existing ones. The present paper is dedicated to a new method of removal of the Zirconia ceramic layer. The method is based on the ice dry removal of the ceramic layer. This method will not impact on the roughness and morphology of the bond coat surface, making it suitable for a further step of TBC coating, without any further operation. This possibility will impact on the stripping costs and time, saving all the operator related to the qualification of t...

3D Metal Printing Technology

IFAC-PapersOnLine, 2016

Abstract: 3D Printing or Additive manufacturing is a novel method of manufacturing parts directly... more Abstract: 3D Printing or Additive manufacturing is a novel method of manufacturing parts directly from digital model by using layer by layer material build-up approach. This tool-less manufacturing method can produce fully dense metallic parts in short time, with high precision. Features of additive manufacturing like freedom of part design, part complexity, light weighting, part consolidation and design for function are garnering particular interests in metal additive manufacturing for aerospace, oil & gas, marine and automobile applications. Powder bed fusion, in which each powder bed layer is selectively fused by using energy source like laser, is the most promising additive manufacturing technology that can be used for manufacturing small, low volume, complex metallic parts. This review presents overview of 3D Printing technologies, materials, applications, advantages, disadvantages, challenges, economics and applications of 3D metal printing technology.

Verfahren zum aufbringen einer schützenden beschichtung auf ein thermisch beanspruchtes bauteil

Productivity Increase by Using Multi-Tools for Coating of Turbine Parts

Method of depositing a local MCrAIY-coating

Method for application of a protective coating to a thermally-stressed component

Measuring Device for Measuring the Temperature of a Thermally Loaded Metallic Base Element, Provided with a Protective Surface Coating, and Method for Producing Such a Measuring Device

High-Speed Imaging and Sequence Analysis III, 2001

In the simplest terms possible, thermal spraying coating involves heating a material, in powder o... more In the simplest terms possible, thermal spraying coating involves heating a material, in powder or wire form, to a molten or semi-molten state. The material is propelled using a heat source, e.g. a very high temperature plasma flame to deposit it, creating a surface structure on a given substrate. The process is very complex because it depends on numerous parameters influencing each other. A necessary condition to improve process efficiency and quality of produced coatings is the determination of in-flight particle properties. The innovative Particle-Shape-Imaging (PSI) technique offers a new potential in particle diagnostics. It is intended for the analysis of size and shape of single particles within the plasma jet. The method is based on telemicroscopic imaging of the particle shades. A cw-laser beam is split into two beams of equal intensities, which are superimposed in the focal plane of a long-distance-microscope. The detection system consists of a CCD camera with a Micro- Channel-Plate intensifier allowing exposure times of a few nanoseconds. When a particle passes the measuring volume, the laser beams generate two individual shades. The position of the particle relatively to the focal plane is determined from the separation of the two shades in the image plane. From the evaluation of area and contour of the shades, particles can be classified in regard to size and form. Corresponding distributions of the particles within the plasma jet as well as changes of the particle form in the melting process can be determined.

Probabilistic Lifetime Prediction of Thermal Barrier Coating Systems Depending on Manufacturing Scatter

Volume 6: Ceramics; Controls, Diagnostics and Instrumentation; Education; Manufacturing Materials and Metallurgy, 2014

The assessment of Bondcoat/Thermal barrier coating systems is an inherent part of the lifing proc... more The assessment of Bondcoat/Thermal barrier coating systems is an inherent part of the lifing process of gas turbine component. On the one hand, coatings are considered in the constitutive modelling — e.g. in the thermal model and for the prediction of eigenfrequencies of gas turbine blades. On the other hand, the influence of the coating system on the lifetime of the part (target cyclic life and target operation hours) needs to be assessed. This paper addresses the prediction of coating lifetime. Lifing models of Bondcoat/Thermal barrier coating systems (BC/TBC) are commonly built using isothermal furnace cyclic tests (FCT). The lifetime of the BC/TBC under such test conditions has been shown to depend on multiple coating parameters like TBC thickness, TBC porosity, BC thickness, BC roughness, and also on testing temperature. For example, the TBC life (defined as time to partial TBC spallation) is reduced with increasing temperature, with increasing TBC thickness and decreasing poro...

Journal of Thermal Spray Technology, 2012

Over the last few years, global economic growth has triggered a dramatic increase in the demand f... more Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments. Keywords atmospheric plasma spray (APS), gas turbines, particle plasma interaction, residual stress determination, thermal barrier coatings (TBCs), torch design, yttria stabilized zirconia (YSZ) This article is an invited paper selected from presentations at the 2011 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously

Thermally Grown Oxides on Electroplated Bond Coats under APS TBC

Thermal Spray 2003: Proceedings from the International Thermal Spray Conference

MCrAlY bond coats were deposited on nickel base substrate by electroplated process. The bond coat... more MCrAlY bond coats were deposited on nickel base substrate by electroplated process. The bond coats were plated using ‘CrAlY’ precursor powders suspended in an electrolytic bath containing nickel and cobalt in solution. The CrAlY powders used had size in the range generally below 10 um. The as-deposited coatings were heat-treated in a vacuum at elevated temperature. The roughness of the as-deposited coatings was on the range from 2 to 4 um (average). Yttria stabilized zirconia thermal barrier coatings, 7YSZ were deposited by air plasma spray. The thickness of the both bond coats and TBCs was varied in order to determine the effects of thickness in the stability of the thermal barrier coatings. The coated samples were tested in a static furnace and also in a thermal shock test rig where the samples could be cooled rapidly from 1000°C to 100°C at a predetermined rate. The TGO formed at temperatures in the range from 800 to 1050°C was characterized by optical, scanning electron microsco...