Mandar Thakare - Academia.edu (original) (raw)
Papers by Mandar Thakare
ABSTRACT Thermal spraying is a dynamic process and a rapidly changing field which is used in a va... more ABSTRACT Thermal spraying is a dynamic process and a rapidly changing field which is used in a variety of industries to solve a number of challenging problems including performance enhancement and extending the life of industrial components which are subjected to wear corrosion. Thermal Sprayed Coatings and their Tribological Performances showcases the latest research surrounding the development and use of thermal spraying techniques as well as the benefits of using thermal sprayed coatings in the industrial sector. Focusing on practical solutions that can be applied to real-world settings, this publication is ideally designed for academicians, upper-level students, as well as engineers and operations managers across industries.
ABSTRACT WC-based thermal-spray type coatings are extensively used in the oil and gas industry an... more ABSTRACT WC-based thermal-spray type coatings are extensively used in the oil and gas industry and are exposed to corrosive environments during operation often leading to premature failure of the coating due to the synergistic effects of wear and corrosion. It is regularly observed that thermal spray coatings used on the helical mud motor rotors have a very different wear-corrosion performance as compared to thermal spray coatings used for other applications, such as radial bearings, despite very similar operating environments. This is due to factors such as pH, time of exposure and contact conditions. As such, the influence of these individual parameters on the wear-corrosion performance of thermal spray coatings needs to be fully understood to develop and tailor surface engineering solutions for specific applications within the bottom hole assembly (BHA). To achieve this, the present paper attempts to decouple the effects of contact conditions and corrosion by examining the wear-corrosion performance of Detonation gun (D-gun) sprayed WC-10Co-4Cr coating using a modified micro-abrasion tester capable of in situ electrochemical measurements and a modified ASTM G65 rubber-wheel abrasion tester under neutral and alkaline test conditions using the same type (SiC) and size (4.5 microns) of abrasive particles. To mimic prolonged exposure to alkaline drilling fluids, select coating specimens were also ‘pre-exposed’ to NaOH solutions with pH 11 before the wear-tests. Scanning electron microscopy and in situ electrochemical noise data has been used to compare the wear-corrosion mechanisms of the coating in the different tests. In addition to parameters such as severity of contact, it is possible to relate the overall wear rates to individual parameters of contact conditions and pH. Additionally, effects of ‘static’ corrosion (pre-exposure), such as depth of attack and partial passivation of the coating were examined using X-ray photoelectron spectroscopy (XPS) and focussed ion beam (FIB) sectioning of the samples.
The present work is a Schlumberger funded PhD project entitled ‘Abrasion-corrosion of downhole dr... more The present work is a Schlumberger funded PhD project entitled ‘Abrasion-corrosion of downhole drill tool components’. The objective of this project was to replicate the wear-corrosion mechanisms of tungsten carbide (WC)-based hardmetals and coatings occurring in downhole environments (pH 9-11) under controlled laboratory conditions, to identify and establish a better understanding these mechanisms and the factors influencing them so as to minimise the material wastage during service. The presence of hard and soft phases within WC-based hardmetals and coatings results in complex wear mechanisms. In addition, the presence of a corrosive environment downhole further complicates the contact conditions and can lead to accelerated surface degradation and even catastrophic failures. A Scanning Electron Microscope (SEM) investigation of worn drill-tool components revealed the presence of micro-scale (by abrasives similar size to the carbide grains i.e. less than 5 ?m) and macroscale abrasi...
Materials Science and Engineering: Concepts, Methodologies, Tools, and Applications, 2000
WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide ... more WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide range of applications ranging from downhole drilling tools to gas turbine engines. WC-based thermal spray coatings offer improved wear resistance as a result of hard phases dispersed in binder-rich regions. However, the presence of hard and soft phases within the coating can also lead to the formation of micro-galvanic couplings in aqueous environments leading to some reduction in combined wearcorrosion resistance. Furthermore, the coating also responds differently to change in mechanical loading conditions. This chapter examines the wear-corrosion performance of thermal spray coatings in a range of wear, electrochemical, and wear-corrosion tests under varying contact conditions to develop models and establish relationships between wear mechanisms, wear rates, and environmental factors such as pH and applied load.
Thermal Sprayed Coatings and their Tribological Performances, 2015
WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide ... more WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide range of applications ranging from downhole drilling tools to gas turbine engines. WC-based thermal spray coatings offer improved wear resistance as a result of hard phases dispersed in binder-rich regions. However, the presence of hard and soft phases within the coating can also lead to the formation of micro-galvanic couplings in aqueous environments leading to some reduction in combined wearcorrosion resistance. Furthermore, the coating also responds differently to change in mechanical loading conditions. This chapter examines the wear-corrosion performance of thermal spray coatings in a range of wear, electrochemical, and wear-corrosion tests under varying contact conditions to develop models and establish relationships between wear mechanisms, wear rates, and environmental factors such as pH and applied load.
WC-based thermal-spray type coatings are extensively used in the oil and gas industry and are exp... more WC-based thermal-spray type coatings are extensively used in the oil and gas industry and are exposed to corrosive environments during operation often leading to premature failure of the coating due to the synergistic effects of wear and corrosion. It is regularly observed that thermal spray coatings used on the helical mud motor rotors have a very different wear-corrosion performance as compared to thermal spray coatings used for other applications, such as radial bearings, despite very similar operating environments. This is due to factors such as pH, time of exposure and contact conditions. As such, the influence of these individual parameters on the wear-corrosion performance of thermal spray coatings needs to be fully understood to develop and tailor surface engineering solutions for specific applications within the bottom hole assembly (BHA). To achieve this, the present paper attempts to decouple the effects of contact conditions and corrosion by examining the wear-corrosion ...
ABSTRACT Thermal spraying is a dynamic process and a rapidly changing field which is used in a va... more ABSTRACT Thermal spraying is a dynamic process and a rapidly changing field which is used in a variety of industries to solve a number of challenging problems including performance enhancement and extending the life of industrial components which are subjected to wear corrosion. Thermal Sprayed Coatings and their Tribological Performances showcases the latest research surrounding the development and use of thermal spraying techniques as well as the benefits of using thermal sprayed coatings in the industrial sector. Focusing on practical solutions that can be applied to real-world settings, this publication is ideally designed for academicians, upper-level students, as well as engineers and operations managers across industries.
ABSTRACT WC-based thermal-spray type coatings are extensively used in the oil and gas industry an... more ABSTRACT WC-based thermal-spray type coatings are extensively used in the oil and gas industry and are exposed to corrosive environments during operation often leading to premature failure of the coating due to the synergistic effects of wear and corrosion. It is regularly observed that thermal spray coatings used on the helical mud motor rotors have a very different wear-corrosion performance as compared to thermal spray coatings used for other applications, such as radial bearings, despite very similar operating environments. This is due to factors such as pH, time of exposure and contact conditions. As such, the influence of these individual parameters on the wear-corrosion performance of thermal spray coatings needs to be fully understood to develop and tailor surface engineering solutions for specific applications within the bottom hole assembly (BHA). To achieve this, the present paper attempts to decouple the effects of contact conditions and corrosion by examining the wear-corrosion performance of Detonation gun (D-gun) sprayed WC-10Co-4Cr coating using a modified micro-abrasion tester capable of in situ electrochemical measurements and a modified ASTM G65 rubber-wheel abrasion tester under neutral and alkaline test conditions using the same type (SiC) and size (4.5 microns) of abrasive particles. To mimic prolonged exposure to alkaline drilling fluids, select coating specimens were also ‘pre-exposed’ to NaOH solutions with pH 11 before the wear-tests. Scanning electron microscopy and in situ electrochemical noise data has been used to compare the wear-corrosion mechanisms of the coating in the different tests. In addition to parameters such as severity of contact, it is possible to relate the overall wear rates to individual parameters of contact conditions and pH. Additionally, effects of ‘static’ corrosion (pre-exposure), such as depth of attack and partial passivation of the coating were examined using X-ray photoelectron spectroscopy (XPS) and focussed ion beam (FIB) sectioning of the samples.
The present work is a Schlumberger funded PhD project entitled ‘Abrasion-corrosion of downhole dr... more The present work is a Schlumberger funded PhD project entitled ‘Abrasion-corrosion of downhole drill tool components’. The objective of this project was to replicate the wear-corrosion mechanisms of tungsten carbide (WC)-based hardmetals and coatings occurring in downhole environments (pH 9-11) under controlled laboratory conditions, to identify and establish a better understanding these mechanisms and the factors influencing them so as to minimise the material wastage during service. The presence of hard and soft phases within WC-based hardmetals and coatings results in complex wear mechanisms. In addition, the presence of a corrosive environment downhole further complicates the contact conditions and can lead to accelerated surface degradation and even catastrophic failures. A Scanning Electron Microscope (SEM) investigation of worn drill-tool components revealed the presence of micro-scale (by abrasives similar size to the carbide grains i.e. less than 5 ?m) and macroscale abrasi...
Materials Science and Engineering: Concepts, Methodologies, Tools, and Applications, 2000
WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide ... more WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide range of applications ranging from downhole drilling tools to gas turbine engines. WC-based thermal spray coatings offer improved wear resistance as a result of hard phases dispersed in binder-rich regions. However, the presence of hard and soft phases within the coating can also lead to the formation of micro-galvanic couplings in aqueous environments leading to some reduction in combined wearcorrosion resistance. Furthermore, the coating also responds differently to change in mechanical loading conditions. This chapter examines the wear-corrosion performance of thermal spray coatings in a range of wear, electrochemical, and wear-corrosion tests under varying contact conditions to develop models and establish relationships between wear mechanisms, wear rates, and environmental factors such as pH and applied load.
Thermal Sprayed Coatings and their Tribological Performances, 2015
WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide ... more WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide range of applications ranging from downhole drilling tools to gas turbine engines. WC-based thermal spray coatings offer improved wear resistance as a result of hard phases dispersed in binder-rich regions. However, the presence of hard and soft phases within the coating can also lead to the formation of micro-galvanic couplings in aqueous environments leading to some reduction in combined wearcorrosion resistance. Furthermore, the coating also responds differently to change in mechanical loading conditions. This chapter examines the wear-corrosion performance of thermal spray coatings in a range of wear, electrochemical, and wear-corrosion tests under varying contact conditions to develop models and establish relationships between wear mechanisms, wear rates, and environmental factors such as pH and applied load.
WC-based thermal-spray type coatings are extensively used in the oil and gas industry and are exp... more WC-based thermal-spray type coatings are extensively used in the oil and gas industry and are exposed to corrosive environments during operation often leading to premature failure of the coating due to the synergistic effects of wear and corrosion. It is regularly observed that thermal spray coatings used on the helical mud motor rotors have a very different wear-corrosion performance as compared to thermal spray coatings used for other applications, such as radial bearings, despite very similar operating environments. This is due to factors such as pH, time of exposure and contact conditions. As such, the influence of these individual parameters on the wear-corrosion performance of thermal spray coatings needs to be fully understood to develop and tailor surface engineering solutions for specific applications within the bottom hole assembly (BHA). To achieve this, the present paper attempts to decouple the effects of contact conditions and corrosion by examining the wear-corrosion ...