The Experts below are selected from a list of 3531 Experts worldwide ranked by ideXlab platform
Rachel Collier - One of the best experts on this subject based on the ideXlab platform.
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Tribological Performance of Molybdenum Stellite Alloys under Dry-Sliding Wear
Journal of Materials Engineering and Performance, 2020Co-Authors: Rachel Collier, Rong Liu, Xiaozhou Zhang, M. X. YaoAbstract:Elements tungsten and molybdenum are the key constituents of Stellite alloys as solutes to strengthen the solid solution matrix. Meanwhile, they also promote formation of W-rich and Mo-rich carbides when present in large quantities in high-carbon Stellite alloys. Extensive studies on tungsten Stellite alloys, in particular, Stellite® 6, have been reported in the literature; however, molybdenum Stellite alloys, especially, the influence of Mo content on the performance of the alloys, have been rarely investigated. In this research, the tribological performance of three molybdenum Stellite alloys with varying C and Mo contents is studied using pin-on-disk dry-sliding wear test at ambient temperature, focusing on the effect of test duration and interrupted test on the wear behavior of the alloys. The worn surfaces are examined using SEM/EDS, and the analyses of the surface morphologies help explore the wear mechanisms of these alloys in dry-sliding condition. A wear model is developed for molybdenum Stellite alloys, based on the Archard equation in check with the wear test data, using hardness as a controlling factor.
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Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum
Metallurgical and Materials Transactions A, 2015Co-Authors: Rong Liu, M. X. Yao, J. H. Yao, Q L Zhang, Rachel CollierAbstract:Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.
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Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum
Metallurgical and Materials Transactions A, 2015Co-Authors: Rong Liu, M. X. Yao, J. H. Yao, Q L Zhang, Rachel CollierAbstract:Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.
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microstructures and hardness wear performance of high carbon Stellite alloys containing molybdenum
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2015Co-Authors: Qunli Zhang, Rachel CollierAbstract:Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.
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effects of molybdenum content on the wear erosion and corrosion performance of low carbon Stellite alloys
Materials & Design, 2015Co-Authors: Qunli Zhang, Rachel CollierAbstract:Abstract The strengthening agents of Stellite alloys are commonly various carbides, but intermetallic compounds may play a similar role to the carbides. In this research two low-carbon Stellite alloys with high molybdenum content are developed and studied, which are modified version of Stellite 21. This particular elemental content combination results in large amounts of Co3Mo intermetallic compound precipitated in these alloys. The microstructures of the alloys are analyzed using SEM/EDX/XRD and DSC. The dry sliding wear resistance and solid-particle erosion resistance of the alloys are evaluated experimentally. The corrosion performance of the alloys in 3.5 wt.% sodium chloride (NaCl) aqueous solution is investigated under electrochemical tests. It is shown that the intermetallic compounds enhance hardness and wear resistance as the carbides do in Stellite alloys, but do not favor solid-particle erosion resistance due to their brittleness. The presence of the intermetallic compounds does not worsen corrosion resistance, compared to Stellite 21.
Rong Liu - One of the best experts on this subject based on the ideXlab platform.
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Tribological Performance of Molybdenum Stellite Alloys under Dry-Sliding Wear
Journal of Materials Engineering and Performance, 2020Co-Authors: Rachel Collier, Rong Liu, Xiaozhou Zhang, M. X. YaoAbstract:Elements tungsten and molybdenum are the key constituents of Stellite alloys as solutes to strengthen the solid solution matrix. Meanwhile, they also promote formation of W-rich and Mo-rich carbides when present in large quantities in high-carbon Stellite alloys. Extensive studies on tungsten Stellite alloys, in particular, Stellite® 6, have been reported in the literature; however, molybdenum Stellite alloys, especially, the influence of Mo content on the performance of the alloys, have been rarely investigated. In this research, the tribological performance of three molybdenum Stellite alloys with varying C and Mo contents is studied using pin-on-disk dry-sliding wear test at ambient temperature, focusing on the effect of test duration and interrupted test on the wear behavior of the alloys. The worn surfaces are examined using SEM/EDS, and the analyses of the surface morphologies help explore the wear mechanisms of these alloys in dry-sliding condition. A wear model is developed for molybdenum Stellite alloys, based on the Archard equation in check with the wear test data, using hardness as a controlling factor.
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Corrosion Performance of 700 Series Stellite Alloys in Various Media
Journal of Materials Engineering and Performance, 2019Co-Authors: Kafeel Kamal, Rong Liu, Jianhua Yao, Y. P. Ding, M. X. YaoAbstract:The corrosion performance of 700 series Stellite alloys including Stellite 706, Stellite 712 and Stellite 720, which are high-carbon high-molybdenum Stellite alloys, in various media such as Green Death solution, 3.5 wt.% NaCl solution and morpholine solution with pH 9.5, is studied using electrochemical and immersion methods. The obtained polarization curves are analyzed along with the corroded surfaces examined using SEM/EDS to investigate the corrosion mechanisms of these alloys. The experimental results reveal that the 700 series Stellite alloys possess excellent corrosion resistance in the tested media, even in the severe corrosive condition—Green Death solution at 60 °C where no noticeable pitting is found on the surfaces of the alloys. It is shown that the corrosion resistance of these Stellite alloys depends strongly on the behavior of the passivation film formed on the alloy surfaces. Additional Mo content in these alloys benefits the stabilization of the passivation film thus enhances the corrosion resistance of the alloys. Both carbon and molybdenum contents affect the passivation film formation and stabilization.
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A composite Stellite alloy hardfacing with improved laser cladding behavior and wear resistance
International Congress on Applications of Lasers & Electro-Optics, 2017Co-Authors: Yinping Ding, Qunli Zhang, Rong Liu, Liang Wang, Jianhua YaoAbstract:To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the same laser process parameters and is also analyzed and tested under the same conditions with the composite Stellite alloy hardfacing for comparison. The experimental results and real industrial test demonstrate superior performance of the composite Stellite alloy hardfacing to Stellite 6 hardfacing for control valve seat sealing application.To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the sa...
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Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum
Metallurgical and Materials Transactions A, 2015Co-Authors: Rong Liu, M. X. Yao, J. H. Yao, Q L Zhang, Rachel CollierAbstract:Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.
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Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum
Metallurgical and Materials Transactions A, 2015Co-Authors: Rong Liu, M. X. Yao, J. H. Yao, Q L Zhang, Rachel CollierAbstract:Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.
Sen Yang - One of the best experts on this subject based on the ideXlab platform.
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high temperature wear resistance and thermal fatigue behavior of Stellite 6 wc coatings produced by laser cladding with co coated wc powder
International Journal of Refractory Metals & Hard Materials, 2019Co-Authors: Guangyuan Wang, Jiazi Zhang, Ruiying Shu, Sen YangAbstract:Abstract The Stellite-6/WC composite coatings were produced on AISI H13 hot work tool steel by laser cladding with mixture of Co-coated WC (WC-12Co) particles and Stellite-6 powder. The phase composition, microstructural characterization, high temperature wear resistance and thermal fatigue behavior of Stellite-6/WC coatings were investigated and compared with the properties of the coatings produced from mixture of WC particles and Stellite-6 powder. The results showed that using the WC-12Co particles alleviated the decomposition of WC and resulted in the weaker intensity of W2C, CoCx and Co6W6C peaks in the X-Ray Diffraction (XRD) patterns. Compared with using the WC particles directly as the coating material, using the WC-12Co particles could further improve the wear resistance of coatings according to the relative lower width and depth of wear scars at the same WC content. In addition, fewer fatigue cracks were observed on the surface of coatings made by adding WC-12Co particles under the same thermal fatigue conditions, which indicates that using WC-12Co is beneficial to extend the life of Stellite-6/WC coatings.
Qunli Zhang - One of the best experts on this subject based on the ideXlab platform.
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wear and corrosion performance of laser clad low carbon high molybdenum Stellite alloys
Optics and Laser Technology, 2018Co-Authors: Yinping Ding, Qunli Zhang, Liang WangAbstract:Abstract Low-carbon Stellite alloys such as Stellite 21 exhibit good high-temperature and corrosion properties but need improved wear resistance in some applications. In this research, two low-carbon Stellite alloys with highly increased molybdenum content are produced via laser cladding. The microstructures of the laser cladding hardfacings are studied using scanning electron microscopy (SEM) with an energy dispersive X-ray (EDS) spectroscopy, and X-ray diffraction. The wear resistance of the hardfacings is evaluated using a pin-on-disc tribometer. The corrosion performance of the hardfacings is investigated under electrochemical tests in 3.5 wt.% sodium chloride (NaCl) solution and in Green Death solution. The experimental results show that the presence of Mo-rich intermetallic compounds enhances the wear resistance of the alloy hardfacings significantly. Since Stellite alloys are all able to form protective oxide films due to high chromium content against corrosion of the substrates, the bonding strength and repair ability of the oxide films dominate the corrosion resistance of the hardfacings in the corrosive environments. Stellite 21 hardfacing is also studied under the same testing conditions for comparison.
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Influence of laser irradiation on deposition characteristics of cold sprayed Stellite-6 coatings
Optics and Laser Technology, 2018Co-Authors: Yan Jin, Qunli Zhang, Jianhua Yao, Xin ZhangAbstract:Abstract Depositing hard materials such as Stellite-6 solely by cold spray (CS) is challengeable due to limited ability of plastic deformation. In this study, the deposition of Stellite-6 powder was achieved by supersonic laser deposition (SLD) which combines CS with synchronous laser irradiation. The surface morphology, deposition efficiency, track shape of Stellite-6 coatings produced over a range of laser irradiation temperatures were examined so as to reveal the effects of varying laser energy inputting on the deposition process of high strength material. The microstructure, phase composition and wear/corrosion resistant properties of the as-deposited Stellite-6 coatings were also investigated. The experimental results demonstrate that the surface flatness and deposition efficiency increase with laser irradiation temperature due to the softening effect induced by laser heating. The as-deposited Stellite-6 tracks show asymmetric shapes which are influenced by the relative configuration of powder stream and laser beam. The SLD coatings can preserve the original microstructure and phase of the feedstock material due to relatively low laser energy inputting, which result in the superior wear/corrosion resistant properties as compared to the counterpart prepared by laser cladding.
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Stellite alloy mixture hardfacing via laser cladding for control valve seat sealing surfaces
Surface & Coatings Technology, 2017Co-Authors: Yinping Ding, Qunli Zhang, Liang WangAbstract:Abstract A Stellite alloy mixture hardfacing consisting of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance compared with Stellite 6, and improving cracking in laser cladding compared with Stellite 3. The Stellite alloy mixture hardfacing is made on 316 stainless steel substrate and does not show any cracking in liquid penetrant testing. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance, cavitation-erosion resistance in NaOH solution and corrosion resistance in morpholine solution at pH 9.5 to simulate the amine environment of boiler feedwater service in power generation plants, are evaluated. The Stellite 6 hardfacing prepared with the same laser process parameters is also analyzed and tested under the same conditions for comparison. The experimental results and real industrial test demonstrate superior performance of the Stellite alloy mixture hardfacing to the Stellite 6 hardfacing for control valve seat sealing application.
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A composite Stellite alloy hardfacing with improved laser cladding behavior and wear resistance
International Congress on Applications of Lasers & Electro-Optics, 2017Co-Authors: Yinping Ding, Qunli Zhang, Rong Liu, Liang Wang, Jianhua YaoAbstract:To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the same laser process parameters and is also analyzed and tested under the same conditions with the composite Stellite alloy hardfacing for comparison. The experimental results and real industrial test demonstrate superior performance of the composite Stellite alloy hardfacing to Stellite 6 hardfacing for control valve seat sealing application.To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the sa...
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microstructures and hardness wear performance of high carbon Stellite alloys containing molybdenum
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2015Co-Authors: Qunli Zhang, Rachel CollierAbstract:Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.
Jianhua Yao - One of the best experts on this subject based on the ideXlab platform.
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Corrosion and Wear Performance of Stellite Alloy Hardfacing Prepared via Laser Cladding
Protection of Metals and Physical Chemistry of Surfaces, 2020Co-Authors: Yinping Ding, R. Liu, Wang Liujing, Li Juehui, Jianhua YaoAbstract:Stellite 6 alloy hardfacing has been popularly applied on the seat face of control valves where both wear and corrosion in various corrosive media are involved. In this research, Stellite 6 alloy hardfacing is prepared via laser cladding and the wear performance and corrosion behavior in morpholine, 3.5 wt % NaCl, and Green Death solution, of this hardfacing are investigated using a pin-on-disc tribometer and a three-electrode cell, respectively. The worn and corroded surfaces are analyzed using SEM/EDS. For comparison, cast Stellite 6 is also studied in parallel. The experimental results show that cast Stellite 6 has better wear resistance than laser clad Stellite 6 but better corrosion resistance in the corrosive media due to better retention of the oxide film on the specimen surface.
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Corrosion Performance of 700 Series Stellite Alloys in Various Media
Journal of Materials Engineering and Performance, 2019Co-Authors: Kafeel Kamal, Rong Liu, Jianhua Yao, Y. P. Ding, M. X. YaoAbstract:The corrosion performance of 700 series Stellite alloys including Stellite 706, Stellite 712 and Stellite 720, which are high-carbon high-molybdenum Stellite alloys, in various media such as Green Death solution, 3.5 wt.% NaCl solution and morpholine solution with pH 9.5, is studied using electrochemical and immersion methods. The obtained polarization curves are analyzed along with the corroded surfaces examined using SEM/EDS to investigate the corrosion mechanisms of these alloys. The experimental results reveal that the 700 series Stellite alloys possess excellent corrosion resistance in the tested media, even in the severe corrosive condition—Green Death solution at 60 °C where no noticeable pitting is found on the surfaces of the alloys. It is shown that the corrosion resistance of these Stellite alloys depends strongly on the behavior of the passivation film formed on the alloy surfaces. Additional Mo content in these alloys benefits the stabilization of the passivation film thus enhances the corrosion resistance of the alloys. Both carbon and molybdenum contents affect the passivation film formation and stabilization.
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Influence of laser irradiation on deposition characteristics of cold sprayed Stellite-6 coatings
Optics and Laser Technology, 2018Co-Authors: Yan Jin, Qunli Zhang, Jianhua Yao, Xin ZhangAbstract:Abstract Depositing hard materials such as Stellite-6 solely by cold spray (CS) is challengeable due to limited ability of plastic deformation. In this study, the deposition of Stellite-6 powder was achieved by supersonic laser deposition (SLD) which combines CS with synchronous laser irradiation. The surface morphology, deposition efficiency, track shape of Stellite-6 coatings produced over a range of laser irradiation temperatures were examined so as to reveal the effects of varying laser energy inputting on the deposition process of high strength material. The microstructure, phase composition and wear/corrosion resistant properties of the as-deposited Stellite-6 coatings were also investigated. The experimental results demonstrate that the surface flatness and deposition efficiency increase with laser irradiation temperature due to the softening effect induced by laser heating. The as-deposited Stellite-6 tracks show asymmetric shapes which are influenced by the relative configuration of powder stream and laser beam. The SLD coatings can preserve the original microstructure and phase of the feedstock material due to relatively low laser energy inputting, which result in the superior wear/corrosion resistant properties as compared to the counterpart prepared by laser cladding.
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A composite Stellite alloy hardfacing with improved laser cladding behavior and wear resistance
International Congress on Applications of Lasers & Electro-Optics, 2017Co-Authors: Yinping Ding, Qunli Zhang, Rong Liu, Liang Wang, Jianhua YaoAbstract:To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the same laser process parameters and is also analyzed and tested under the same conditions with the composite Stellite alloy hardfacing for comparison. The experimental results and real industrial test demonstrate superior performance of the composite Stellite alloy hardfacing to Stellite 6 hardfacing for control valve seat sealing application.To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the sa...
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Effects of molybdenum content on the wear/erosion and corrosion performance of low-carbon Stellite alloys
Materials & Design, 2015Co-Authors: Rong Liu, M. X. Yao, Qunli Zhang, Jianhua Yao, Rachel CollierAbstract:Abstract The strengthening agents of Stellite alloys are commonly various carbides, but intermetallic compounds may play a similar role to the carbides. In this research two low-carbon Stellite alloys with high molybdenum content are developed and studied, which are modified version of Stellite 21. This particular elemental content combination results in large amounts of Co3Mo intermetallic compound precipitated in these alloys. The microstructures of the alloys are analyzed using SEM/EDX/XRD and DSC. The dry sliding wear resistance and solid-particle erosion resistance of the alloys are evaluated experimentally. The corrosion performance of the alloys in 3.5 wt.% sodium chloride (NaCl) aqueous solution is investigated under electrochemical tests. It is shown that the intermetallic compounds enhance hardness and wear resistance as the carbides do in Stellite alloys, but do not favor solid-particle erosion resistance due to their brittleness. The presence of the intermetallic compounds does not worsen corrosion resistance, compared to Stellite 21.
