In the present paper, we have investigated the tribological properties and microstructure of the used gear oil theoretically and experimentally. The deterioration process of the in-service gear lubricant oils was also...In the present paper, we have investigated the tribological properties and microstructure of the used gear oil theoretically and experimentally. The deterioration process of the in-service gear lubricant oils was also discussed. The viscosity and microstructure of oils running different mileages were analyzed by viscometer and Fourier Transform Infrared Spectroscopy (FTIR), respectively. In addition, the friction and wear behaviors of the friction pair of the GCr15 steel ball and disc were investigated using a ball on disc tribometer under different mileages’ gear oils lubrication conditions. These techniques give reproducible and reliable data with which to evaluate the severity of deterioration process of oils. The objective of this work is to understand the deterioration process of gear oil and analyze the influence of deterioration on the performance and microstructure of lubricant oils used in gear box. Possible explanations of deterioration process as well as its influence on friction and wear behaviors are also discussed. The results reveals the tribological properties of used oils depended on strongly the microstructure and its deterioration process of oil.展开更多
Vehicle fuel economy will continue to increase in importance as world vehicle production grows and fuel supplies become more limited year by year.As OEMs strive to produce cars and trucks with greater fuel efficiency ...Vehicle fuel economy will continue to increase in importance as world vehicle production grows and fuel supplies become more limited year by year.As OEMs strive to produce cars and trucks with greater fuel efficiency and extended durability,additive technology developers are increasingly being asked to contribute to these goals from the lubricant side.Axle inefficiency can account for as much as 10% of the overall losses in an automotive driveline so improvements in axle efficiency can contribute greatly to improving vehicle fuel economy.For good durability,low axle oil operating temperatures are also needed to minimize oxidative and thermal degradation of the oil,reduce deposits and sludge formation,and extend oil drain intervals.To develop gear oils that can increase axle efficiency significantly while maintaining stable operating temperatures requires rig tests that are fast,precise and reproducible.This paper documents the development of a new axle test rig and test procedures and presents test results on several gear oils.The test results show the contributions of base oil viscosity,base oil chemistry,and additive chemistry on the fuel economy and temperature of the various oils.Having a dependable tool is enabling the development of new fuel-efficient and durable gear oil technology.展开更多
Low temperature fluidity of gear oils is an important fluid property as it directly impacts the useful life of a gear set.This paper compares low temperature fluidity measurement precision of ASTM D6821 and ASTM D2983...Low temperature fluidity of gear oils is an important fluid property as it directly impacts the useful life of a gear set.This paper compares low temperature fluidity measurement precision of ASTM D6821 and ASTM D2983.Both tests are identical in the way they thermally condition the sample prior to viscosity measurement.While ASTM D2983 is cited in many current specifications,ASTM D6821 offers users and formulators a more accurate estimate of gear oil low temperature fluidity.The primary benefit in using ASTM D6821 is better precision.ASTM D6821 accomplishes this by automating the steps from prior to preheat through to viscosity measurement at end of test.展开更多
The elastohydrodynamic(EHD)friction properties of seven ISO VG 320 gear oils including three polyalphaolefins(PAOs),three polyglycols(PG)and a mineral oil have been investigated in rolling/sliding conditions at six di...The elastohydrodynamic(EHD)friction properties of seven ISO VG 320 gear oils including three polyalphaolefins(PAOs),three polyglycols(PG)and a mineral oil have been investigated in rolling/sliding conditions at six different temperatures and three roughnesses.Film thickness,Stribeck and traction curves have been generated using a ball‐on‐disc tribometer.Film thickness results are in agreement with previous work that it is primarily controlled by pressure‐viscosity coefficient and viscosity of lubricants.The results with smooth surface show that all oils experience significant shear heating leading to friction reduction at higher strain rates or lambda ratios but only PGs reach limiting friction whereas mineral oil and PAOs do not.Friction curves obtained at different temperatures and roughnesses enable simulating an extensive range of lubrication regimes and allow isothermal friction correction for shear heating.Stribeck curves with rough surfaces show an increase in friction in the lambda range of 0.5–3.5,where asperity separation varies from partial to full–indicating that roughness effects can be expected even under full film condition.This increase in friction is attributed to formation of a micro‐EHD region,and is seen only with mineral oil and PAOs whereas not with PGs.The results also highlight how EHD friction properties of different family of fluids could be influenced by roughness effects,and the possible mechanisms are discussed.展开更多
文摘In the present paper, we have investigated the tribological properties and microstructure of the used gear oil theoretically and experimentally. The deterioration process of the in-service gear lubricant oils was also discussed. The viscosity and microstructure of oils running different mileages were analyzed by viscometer and Fourier Transform Infrared Spectroscopy (FTIR), respectively. In addition, the friction and wear behaviors of the friction pair of the GCr15 steel ball and disc were investigated using a ball on disc tribometer under different mileages’ gear oils lubrication conditions. These techniques give reproducible and reliable data with which to evaluate the severity of deterioration process of oils. The objective of this work is to understand the deterioration process of gear oil and analyze the influence of deterioration on the performance and microstructure of lubricant oils used in gear box. Possible explanations of deterioration process as well as its influence on friction and wear behaviors are also discussed. The results reveals the tribological properties of used oils depended on strongly the microstructure and its deterioration process of oil.
文摘Vehicle fuel economy will continue to increase in importance as world vehicle production grows and fuel supplies become more limited year by year.As OEMs strive to produce cars and trucks with greater fuel efficiency and extended durability,additive technology developers are increasingly being asked to contribute to these goals from the lubricant side.Axle inefficiency can account for as much as 10% of the overall losses in an automotive driveline so improvements in axle efficiency can contribute greatly to improving vehicle fuel economy.For good durability,low axle oil operating temperatures are also needed to minimize oxidative and thermal degradation of the oil,reduce deposits and sludge formation,and extend oil drain intervals.To develop gear oils that can increase axle efficiency significantly while maintaining stable operating temperatures requires rig tests that are fast,precise and reproducible.This paper documents the development of a new axle test rig and test procedures and presents test results on several gear oils.The test results show the contributions of base oil viscosity,base oil chemistry,and additive chemistry on the fuel economy and temperature of the various oils.Having a dependable tool is enabling the development of new fuel-efficient and durable gear oil technology.
文摘Low temperature fluidity of gear oils is an important fluid property as it directly impacts the useful life of a gear set.This paper compares low temperature fluidity measurement precision of ASTM D6821 and ASTM D2983.Both tests are identical in the way they thermally condition the sample prior to viscosity measurement.While ASTM D2983 is cited in many current specifications,ASTM D6821 offers users and formulators a more accurate estimate of gear oil low temperature fluidity.The primary benefit in using ASTM D6821 is better precision.ASTM D6821 accomplishes this by automating the steps from prior to preheat through to viscosity measurement at end of test.
文摘The elastohydrodynamic(EHD)friction properties of seven ISO VG 320 gear oils including three polyalphaolefins(PAOs),three polyglycols(PG)and a mineral oil have been investigated in rolling/sliding conditions at six different temperatures and three roughnesses.Film thickness,Stribeck and traction curves have been generated using a ball‐on‐disc tribometer.Film thickness results are in agreement with previous work that it is primarily controlled by pressure‐viscosity coefficient and viscosity of lubricants.The results with smooth surface show that all oils experience significant shear heating leading to friction reduction at higher strain rates or lambda ratios but only PGs reach limiting friction whereas mineral oil and PAOs do not.Friction curves obtained at different temperatures and roughnesses enable simulating an extensive range of lubrication regimes and allow isothermal friction correction for shear heating.Stribeck curves with rough surfaces show an increase in friction in the lambda range of 0.5–3.5,where asperity separation varies from partial to full–indicating that roughness effects can be expected even under full film condition.This increase in friction is attributed to formation of a micro‐EHD region,and is seen only with mineral oil and PAOs whereas not with PGs.The results also highlight how EHD friction properties of different family of fluids could be influenced by roughness effects,and the possible mechanisms are discussed.
