The Experts below are selected from a list of 8970 Experts worldwide ranked by ideXlab platform
Richard J Vickerman - One of the best experts on this subject based on the ideXlab platform.
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Tribochemistry on Clutch Friction Material Lubricated by Automatic Transmission Fluids and the Link to Frictional Performance
Journal of Tribology, 2013Co-Authors: Hongyuan Zhao, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Automatic Transmissions (AT) for passenger cars are becoming more popular globally, including some countries that traditionally prefer manual Transmissions. Some new friction modifiers for Transmission fluid technologies have also emerged due to the downsizing trend of Transmissions. In order to study the tribology and tribochemistry effects of some new automatic Transmission fluid (ATF) additive formulations, both steel and wet-clutch friction materials were assessed by using surface analysis techniques. A variable speed friction test (VSFT) rig was used to study the antishudder properties in lock-up clutch tests and friction modifying mechanisms of ATFs. A test oil matrix containing basic ATF components was tested. The friction results were analyzed using both the linear-defined multiple parameter spider chart ATF evaluation (LSAE) method (Zhao et al., 2008, “A New Method to Evaluate the Overall Anti-Shudder Property of Automatic Transmission Fluids—Multiple Parameters Spider Chart Evaluation,” Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol., 222(J3), pp. 459–470) and the friction coefficient ratio index method (Zhao et al., 2011, “Understanding Friction Behavior in Automatic Transmission Fluid LVFA Test: A New Positive Curve Parameter to Friction Coefficient Ratio Index Evaluation,” ASME J. Tribol., 133(2), p. 021802) (e.g., μ1/μ50 on the low-velocity friction apparatus (LVFA) μ-v curve results to compare the overall tribosystem and the snapshot friction performance during the test). Surface analysis results were obtained by using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR FT-IR), and they are presented in this study to investigate the tribofilm compositions formed by different additive formulations. Some organic functional groups were found at the sample surfaces, such as –OH and O–C–O, and their presence is proposed to have a beneficial influence on the ATF friction performance. This paper discusses the surface analysis results of the test sample pieces, the possible links between specific functional groups and friction performance, and the proposed pathways of additive decompositions by using chemical bond dissociation energy comparisons.
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Improved anti-shudder performance of ATFs—Influence of a new friction modifier and surface chemistry
Tribology International, 2012Co-Authors: Hongyuan Zhao, Richard J Vickerman, Ardian Morina, Anne Neville, John DurhamAbstract:Abstract Among OEM strategies for increasing fuel economy and reducing emissions, driveline performance optimisation by using automatic Transmissions is particularly important. Technology advances in automatic Transmission designs are leading to continued growth of the number of vehicles with automatic Transmissions. In fact, over the next five years, it is expected that the market share for automatic Transmissions will increase to greater than 60%, with Europe being the largest region for this growth. The performance of automatic Transmissions, especially anti-shudder performance, is highly dependent on friction modifiers and other additives in automatic Transmission Fluids (ATFs). These additives, in a manner similar to engine oil additives, are expected to interact with the steel and clutch material surfaces to form surface films that provide the desired performance. Hence, understanding the tribochemical processes in this automatic Transmission system is a very important step towards performance optimisation. While the tribochemistry of engine oil additives and the nature of tribofilms on metallic surfaces are relatively well researched, the tribochemistry of ATFs still remains largely unclear. One reason for this is the level of complexity in analysing the friction materials of automatic Transmission systems. Separating lubricant-derived species from the composite clutch friction materials is not trivial. This paper presents a comprehensive look at the tribochemistry of a new friction modifier in ATF systems and assesses the nature of the tribofilms formed on steel and composite friction materials in a variable speed friction test (VSFT) apparatus, which was used to simulate the clutch friction process. The tribofilm evolution is correlated with the tribological response as ageing occurs. Functional groups from the friction modifiers were found on the friction couple surfaces after the test and the mode of their action is discussed. These groups were proposed to form a layer of tribofilm on the top surface after rubbing. The correlation between observed tribochemistry processes and the tribological performance are discussed in detail.
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understanding friction behavior in automatic Transmission fluid lvfa test a new positive curve parameter to friction coefficient ratio index evaluation
Journal of Tribology-transactions of The Asme, 2011Co-Authors: Hongyuan Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:The frictional characteristics of some basic additive systems used in automatic Transmission Fluids (ATFs) were assessed using a variable speed friction test machine. The test evaluates the coefficient of friction in unidirectional sliding contact over a range of speeds, loads, and temperatures. Tests were performed on a steel-versus-clutch friction material tribocouple, mainly to establish the link between the lubricant/surface interactions and additive system performance. A new parameter that measures the positive μ-v curve slope speed range was applied, together with friction coefficient ratio index, to show the antishudder property. It is suggested that this is a good complimentary method to the friction coefficient ratio index evaluation. Lubricant formulation is important to the overall friction performance. Both friction modifiers and detergents are shown to be important to the ATF antishudder performance. Oil absorption ability of the post-test friction material surface is proposed to be an important parameter to indicate the anti-shudder durability in the test. The detergent and antiwear agents are also suggested to be responsible for the decreased oil absorption and pore plugging of the friction material surface.
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A new method to evaluate the overall anti-shudder property of automatic Transmission Fluids – multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
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a new method to evaluate the overall anti shudder property of automatic Transmission Fluids multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
Anne Neville - One of the best experts on this subject based on the ideXlab platform.
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Tribochemistry on Clutch Friction Material Lubricated by Automatic Transmission Fluids and the Link to Frictional Performance
Journal of Tribology, 2013Co-Authors: Hongyuan Zhao, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Automatic Transmissions (AT) for passenger cars are becoming more popular globally, including some countries that traditionally prefer manual Transmissions. Some new friction modifiers for Transmission fluid technologies have also emerged due to the downsizing trend of Transmissions. In order to study the tribology and tribochemistry effects of some new automatic Transmission fluid (ATF) additive formulations, both steel and wet-clutch friction materials were assessed by using surface analysis techniques. A variable speed friction test (VSFT) rig was used to study the antishudder properties in lock-up clutch tests and friction modifying mechanisms of ATFs. A test oil matrix containing basic ATF components was tested. The friction results were analyzed using both the linear-defined multiple parameter spider chart ATF evaluation (LSAE) method (Zhao et al., 2008, “A New Method to Evaluate the Overall Anti-Shudder Property of Automatic Transmission Fluids—Multiple Parameters Spider Chart Evaluation,” Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol., 222(J3), pp. 459–470) and the friction coefficient ratio index method (Zhao et al., 2011, “Understanding Friction Behavior in Automatic Transmission Fluid LVFA Test: A New Positive Curve Parameter to Friction Coefficient Ratio Index Evaluation,” ASME J. Tribol., 133(2), p. 021802) (e.g., μ1/μ50 on the low-velocity friction apparatus (LVFA) μ-v curve results to compare the overall tribosystem and the snapshot friction performance during the test). Surface analysis results were obtained by using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR FT-IR), and they are presented in this study to investigate the tribofilm compositions formed by different additive formulations. Some organic functional groups were found at the sample surfaces, such as –OH and O–C–O, and their presence is proposed to have a beneficial influence on the ATF friction performance. This paper discusses the surface analysis results of the test sample pieces, the possible links between specific functional groups and friction performance, and the proposed pathways of additive decompositions by using chemical bond dissociation energy comparisons.
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Improved anti-shudder performance of ATFs—Influence of a new friction modifier and surface chemistry
Tribology International, 2012Co-Authors: Hongyuan Zhao, Richard J Vickerman, Ardian Morina, Anne Neville, John DurhamAbstract:Abstract Among OEM strategies for increasing fuel economy and reducing emissions, driveline performance optimisation by using automatic Transmissions is particularly important. Technology advances in automatic Transmission designs are leading to continued growth of the number of vehicles with automatic Transmissions. In fact, over the next five years, it is expected that the market share for automatic Transmissions will increase to greater than 60%, with Europe being the largest region for this growth. The performance of automatic Transmissions, especially anti-shudder performance, is highly dependent on friction modifiers and other additives in automatic Transmission Fluids (ATFs). These additives, in a manner similar to engine oil additives, are expected to interact with the steel and clutch material surfaces to form surface films that provide the desired performance. Hence, understanding the tribochemical processes in this automatic Transmission system is a very important step towards performance optimisation. While the tribochemistry of engine oil additives and the nature of tribofilms on metallic surfaces are relatively well researched, the tribochemistry of ATFs still remains largely unclear. One reason for this is the level of complexity in analysing the friction materials of automatic Transmission systems. Separating lubricant-derived species from the composite clutch friction materials is not trivial. This paper presents a comprehensive look at the tribochemistry of a new friction modifier in ATF systems and assesses the nature of the tribofilms formed on steel and composite friction materials in a variable speed friction test (VSFT) apparatus, which was used to simulate the clutch friction process. The tribofilm evolution is correlated with the tribological response as ageing occurs. Functional groups from the friction modifiers were found on the friction couple surfaces after the test and the mode of their action is discussed. These groups were proposed to form a layer of tribofilm on the top surface after rubbing. The correlation between observed tribochemistry processes and the tribological performance are discussed in detail.
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understanding friction behavior in automatic Transmission fluid lvfa test a new positive curve parameter to friction coefficient ratio index evaluation
Journal of Tribology-transactions of The Asme, 2011Co-Authors: Hongyuan Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:The frictional characteristics of some basic additive systems used in automatic Transmission Fluids (ATFs) were assessed using a variable speed friction test machine. The test evaluates the coefficient of friction in unidirectional sliding contact over a range of speeds, loads, and temperatures. Tests were performed on a steel-versus-clutch friction material tribocouple, mainly to establish the link between the lubricant/surface interactions and additive system performance. A new parameter that measures the positive μ-v curve slope speed range was applied, together with friction coefficient ratio index, to show the antishudder property. It is suggested that this is a good complimentary method to the friction coefficient ratio index evaluation. Lubricant formulation is important to the overall friction performance. Both friction modifiers and detergents are shown to be important to the ATF antishudder performance. Oil absorption ability of the post-test friction material surface is proposed to be an important parameter to indicate the anti-shudder durability in the test. The detergent and antiwear agents are also suggested to be responsible for the decreased oil absorption and pore plugging of the friction material surface.
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A new method to evaluate the overall anti-shudder property of automatic Transmission Fluids – multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
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a new method to evaluate the overall anti shudder property of automatic Transmission Fluids multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
Ardian Morina - One of the best experts on this subject based on the ideXlab platform.
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Tribochemistry on Clutch Friction Material Lubricated by Automatic Transmission Fluids and the Link to Frictional Performance
Journal of Tribology, 2013Co-Authors: Hongyuan Zhao, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Automatic Transmissions (AT) for passenger cars are becoming more popular globally, including some countries that traditionally prefer manual Transmissions. Some new friction modifiers for Transmission fluid technologies have also emerged due to the downsizing trend of Transmissions. In order to study the tribology and tribochemistry effects of some new automatic Transmission fluid (ATF) additive formulations, both steel and wet-clutch friction materials were assessed by using surface analysis techniques. A variable speed friction test (VSFT) rig was used to study the antishudder properties in lock-up clutch tests and friction modifying mechanisms of ATFs. A test oil matrix containing basic ATF components was tested. The friction results were analyzed using both the linear-defined multiple parameter spider chart ATF evaluation (LSAE) method (Zhao et al., 2008, “A New Method to Evaluate the Overall Anti-Shudder Property of Automatic Transmission Fluids—Multiple Parameters Spider Chart Evaluation,” Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol., 222(J3), pp. 459–470) and the friction coefficient ratio index method (Zhao et al., 2011, “Understanding Friction Behavior in Automatic Transmission Fluid LVFA Test: A New Positive Curve Parameter to Friction Coefficient Ratio Index Evaluation,” ASME J. Tribol., 133(2), p. 021802) (e.g., μ1/μ50 on the low-velocity friction apparatus (LVFA) μ-v curve results to compare the overall tribosystem and the snapshot friction performance during the test). Surface analysis results were obtained by using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR FT-IR), and they are presented in this study to investigate the tribofilm compositions formed by different additive formulations. Some organic functional groups were found at the sample surfaces, such as –OH and O–C–O, and their presence is proposed to have a beneficial influence on the ATF friction performance. This paper discusses the surface analysis results of the test sample pieces, the possible links between specific functional groups and friction performance, and the proposed pathways of additive decompositions by using chemical bond dissociation energy comparisons.
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Improved anti-shudder performance of ATFs—Influence of a new friction modifier and surface chemistry
Tribology International, 2012Co-Authors: Hongyuan Zhao, Richard J Vickerman, Ardian Morina, Anne Neville, John DurhamAbstract:Abstract Among OEM strategies for increasing fuel economy and reducing emissions, driveline performance optimisation by using automatic Transmissions is particularly important. Technology advances in automatic Transmission designs are leading to continued growth of the number of vehicles with automatic Transmissions. In fact, over the next five years, it is expected that the market share for automatic Transmissions will increase to greater than 60%, with Europe being the largest region for this growth. The performance of automatic Transmissions, especially anti-shudder performance, is highly dependent on friction modifiers and other additives in automatic Transmission Fluids (ATFs). These additives, in a manner similar to engine oil additives, are expected to interact with the steel and clutch material surfaces to form surface films that provide the desired performance. Hence, understanding the tribochemical processes in this automatic Transmission system is a very important step towards performance optimisation. While the tribochemistry of engine oil additives and the nature of tribofilms on metallic surfaces are relatively well researched, the tribochemistry of ATFs still remains largely unclear. One reason for this is the level of complexity in analysing the friction materials of automatic Transmission systems. Separating lubricant-derived species from the composite clutch friction materials is not trivial. This paper presents a comprehensive look at the tribochemistry of a new friction modifier in ATF systems and assesses the nature of the tribofilms formed on steel and composite friction materials in a variable speed friction test (VSFT) apparatus, which was used to simulate the clutch friction process. The tribofilm evolution is correlated with the tribological response as ageing occurs. Functional groups from the friction modifiers were found on the friction couple surfaces after the test and the mode of their action is discussed. These groups were proposed to form a layer of tribofilm on the top surface after rubbing. The correlation between observed tribochemistry processes and the tribological performance are discussed in detail.
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understanding friction behavior in automatic Transmission fluid lvfa test a new positive curve parameter to friction coefficient ratio index evaluation
Journal of Tribology-transactions of The Asme, 2011Co-Authors: Hongyuan Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:The frictional characteristics of some basic additive systems used in automatic Transmission Fluids (ATFs) were assessed using a variable speed friction test machine. The test evaluates the coefficient of friction in unidirectional sliding contact over a range of speeds, loads, and temperatures. Tests were performed on a steel-versus-clutch friction material tribocouple, mainly to establish the link between the lubricant/surface interactions and additive system performance. A new parameter that measures the positive μ-v curve slope speed range was applied, together with friction coefficient ratio index, to show the antishudder property. It is suggested that this is a good complimentary method to the friction coefficient ratio index evaluation. Lubricant formulation is important to the overall friction performance. Both friction modifiers and detergents are shown to be important to the ATF antishudder performance. Oil absorption ability of the post-test friction material surface is proposed to be an important parameter to indicate the anti-shudder durability in the test. The detergent and antiwear agents are also suggested to be responsible for the decreased oil absorption and pore plugging of the friction material surface.
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A new method to evaluate the overall anti-shudder property of automatic Transmission Fluids – multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
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a new method to evaluate the overall anti shudder property of automatic Transmission Fluids multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
John Durham - One of the best experts on this subject based on the ideXlab platform.
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Improved anti-shudder performance of ATFs—Influence of a new friction modifier and surface chemistry
Tribology International, 2012Co-Authors: Hongyuan Zhao, Richard J Vickerman, Ardian Morina, Anne Neville, John DurhamAbstract:Abstract Among OEM strategies for increasing fuel economy and reducing emissions, driveline performance optimisation by using automatic Transmissions is particularly important. Technology advances in automatic Transmission designs are leading to continued growth of the number of vehicles with automatic Transmissions. In fact, over the next five years, it is expected that the market share for automatic Transmissions will increase to greater than 60%, with Europe being the largest region for this growth. The performance of automatic Transmissions, especially anti-shudder performance, is highly dependent on friction modifiers and other additives in automatic Transmission Fluids (ATFs). These additives, in a manner similar to engine oil additives, are expected to interact with the steel and clutch material surfaces to form surface films that provide the desired performance. Hence, understanding the tribochemical processes in this automatic Transmission system is a very important step towards performance optimisation. While the tribochemistry of engine oil additives and the nature of tribofilms on metallic surfaces are relatively well researched, the tribochemistry of ATFs still remains largely unclear. One reason for this is the level of complexity in analysing the friction materials of automatic Transmission systems. Separating lubricant-derived species from the composite clutch friction materials is not trivial. This paper presents a comprehensive look at the tribochemistry of a new friction modifier in ATF systems and assesses the nature of the tribofilms formed on steel and composite friction materials in a variable speed friction test (VSFT) apparatus, which was used to simulate the clutch friction process. The tribofilm evolution is correlated with the tribological response as ageing occurs. Functional groups from the friction modifiers were found on the friction couple surfaces after the test and the mode of their action is discussed. These groups were proposed to form a layer of tribofilm on the top surface after rubbing. The correlation between observed tribochemistry processes and the tribological performance are discussed in detail.
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understanding friction behavior in automatic Transmission fluid lvfa test a new positive curve parameter to friction coefficient ratio index evaluation
Journal of Tribology-transactions of The Asme, 2011Co-Authors: Hongyuan Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:The frictional characteristics of some basic additive systems used in automatic Transmission Fluids (ATFs) were assessed using a variable speed friction test machine. The test evaluates the coefficient of friction in unidirectional sliding contact over a range of speeds, loads, and temperatures. Tests were performed on a steel-versus-clutch friction material tribocouple, mainly to establish the link between the lubricant/surface interactions and additive system performance. A new parameter that measures the positive μ-v curve slope speed range was applied, together with friction coefficient ratio index, to show the antishudder property. It is suggested that this is a good complimentary method to the friction coefficient ratio index evaluation. Lubricant formulation is important to the overall friction performance. Both friction modifiers and detergents are shown to be important to the ATF antishudder performance. Oil absorption ability of the post-test friction material surface is proposed to be an important parameter to indicate the anti-shudder durability in the test. The detergent and antiwear agents are also suggested to be responsible for the decreased oil absorption and pore plugging of the friction material surface.
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A new method to evaluate the overall anti-shudder property of automatic Transmission Fluids – multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
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a new method to evaluate the overall anti shudder property of automatic Transmission Fluids multiple parameters spider chart evaluation
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2008Co-Authors: H Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Formulating automatic Transmission Fluids (ATFs) can pose some diverse challenges. The friction response should ensure a smooth engagement process with no shudder in the automatic Transmission. Friction, as a function of velocity, must show a smooth and positive/plateau curve as velocity increases in the μ−v plots. In this study, the friction behaviour of some basic additive systems for ATFs was assessed by using a variable speed friction test (VSFT) rig. The test was used to mimic the clutch engagement process and to evaluate the friction response of different formulations. The focus was anti-shudder properties of the designated formulations. A new method of evaluating VSFT results was developed to assess the overall ATF friction behaviour in conjunction to the common friction—velocity curve analysis. X-ray photoelectron spectroscopy was used to check the different surface conditions before and after the test.
Hongyuan Zhao - One of the best experts on this subject based on the ideXlab platform.
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Tribochemistry on Clutch Friction Material Lubricated by Automatic Transmission Fluids and the Link to Frictional Performance
Journal of Tribology, 2013Co-Authors: Hongyuan Zhao, Ardian Morina, Anne Neville, Richard J VickermanAbstract:Automatic Transmissions (AT) for passenger cars are becoming more popular globally, including some countries that traditionally prefer manual Transmissions. Some new friction modifiers for Transmission fluid technologies have also emerged due to the downsizing trend of Transmissions. In order to study the tribology and tribochemistry effects of some new automatic Transmission fluid (ATF) additive formulations, both steel and wet-clutch friction materials were assessed by using surface analysis techniques. A variable speed friction test (VSFT) rig was used to study the antishudder properties in lock-up clutch tests and friction modifying mechanisms of ATFs. A test oil matrix containing basic ATF components was tested. The friction results were analyzed using both the linear-defined multiple parameter spider chart ATF evaluation (LSAE) method (Zhao et al., 2008, “A New Method to Evaluate the Overall Anti-Shudder Property of Automatic Transmission Fluids—Multiple Parameters Spider Chart Evaluation,” Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol., 222(J3), pp. 459–470) and the friction coefficient ratio index method (Zhao et al., 2011, “Understanding Friction Behavior in Automatic Transmission Fluid LVFA Test: A New Positive Curve Parameter to Friction Coefficient Ratio Index Evaluation,” ASME J. Tribol., 133(2), p. 021802) (e.g., μ1/μ50 on the low-velocity friction apparatus (LVFA) μ-v curve results to compare the overall tribosystem and the snapshot friction performance during the test). Surface analysis results were obtained by using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR FT-IR), and they are presented in this study to investigate the tribofilm compositions formed by different additive formulations. Some organic functional groups were found at the sample surfaces, such as –OH and O–C–O, and their presence is proposed to have a beneficial influence on the ATF friction performance. This paper discusses the surface analysis results of the test sample pieces, the possible links between specific functional groups and friction performance, and the proposed pathways of additive decompositions by using chemical bond dissociation energy comparisons.
-
Improved anti-shudder performance of ATFs—Influence of a new friction modifier and surface chemistry
Tribology International, 2012Co-Authors: Hongyuan Zhao, Richard J Vickerman, Ardian Morina, Anne Neville, John DurhamAbstract:Abstract Among OEM strategies for increasing fuel economy and reducing emissions, driveline performance optimisation by using automatic Transmissions is particularly important. Technology advances in automatic Transmission designs are leading to continued growth of the number of vehicles with automatic Transmissions. In fact, over the next five years, it is expected that the market share for automatic Transmissions will increase to greater than 60%, with Europe being the largest region for this growth. The performance of automatic Transmissions, especially anti-shudder performance, is highly dependent on friction modifiers and other additives in automatic Transmission Fluids (ATFs). These additives, in a manner similar to engine oil additives, are expected to interact with the steel and clutch material surfaces to form surface films that provide the desired performance. Hence, understanding the tribochemical processes in this automatic Transmission system is a very important step towards performance optimisation. While the tribochemistry of engine oil additives and the nature of tribofilms on metallic surfaces are relatively well researched, the tribochemistry of ATFs still remains largely unclear. One reason for this is the level of complexity in analysing the friction materials of automatic Transmission systems. Separating lubricant-derived species from the composite clutch friction materials is not trivial. This paper presents a comprehensive look at the tribochemistry of a new friction modifier in ATF systems and assesses the nature of the tribofilms formed on steel and composite friction materials in a variable speed friction test (VSFT) apparatus, which was used to simulate the clutch friction process. The tribofilm evolution is correlated with the tribological response as ageing occurs. Functional groups from the friction modifiers were found on the friction couple surfaces after the test and the mode of their action is discussed. These groups were proposed to form a layer of tribofilm on the top surface after rubbing. The correlation between observed tribochemistry processes and the tribological performance are discussed in detail.
-
understanding friction behavior in automatic Transmission fluid lvfa test a new positive curve parameter to friction coefficient ratio index evaluation
Journal of Tribology-transactions of The Asme, 2011Co-Authors: Hongyuan Zhao, John Durham, Ardian Morina, Anne Neville, Richard J VickermanAbstract:The frictional characteristics of some basic additive systems used in automatic Transmission Fluids (ATFs) were assessed using a variable speed friction test machine. The test evaluates the coefficient of friction in unidirectional sliding contact over a range of speeds, loads, and temperatures. Tests were performed on a steel-versus-clutch friction material tribocouple, mainly to establish the link between the lubricant/surface interactions and additive system performance. A new parameter that measures the positive μ-v curve slope speed range was applied, together with friction coefficient ratio index, to show the antishudder property. It is suggested that this is a good complimentary method to the friction coefficient ratio index evaluation. Lubricant formulation is important to the overall friction performance. Both friction modifiers and detergents are shown to be important to the ATF antishudder performance. Oil absorption ability of the post-test friction material surface is proposed to be an important parameter to indicate the anti-shudder durability in the test. The detergent and antiwear agents are also suggested to be responsible for the decreased oil absorption and pore plugging of the friction material surface.
