Most view articles
2018, 43(3):11-16.
DOI: 10.3969/j.issn.0254-0150.2018.03.002
Abstract:
Abrasive wear is a major mechanism that affects the service lives of machines.For the ploughing wear mechanism,the wear debris was modeled respectively with spherical and the likely fractal debris,and abrasive wear was divided into three processes:pressing,sliding and crushing.With the finite element software ANSYS,the Mises stress and shear stress distribution and their changes with the depth of the surface increasing were studied,and analysis results of the two models were compared.The results demonstrate that,in the spherical model,the distribution of Mises stress and shear stress at the contact area between the debris and the contact surface is more dispersed,and the stress peak value is smaller,and neither the abrasive debris nor the contact surface is crushed;however,in the fractal model,the distribution of Mises stress and shear stress at the contact area between the debris and the contact surface is more concentrated,and the corresponding stress peak value is higher,and the debris and the contact surface are both crushed.For the two models,the fractal shape of abrasive particles constructed with fractal method is more similar to the actual shape of the wear debris.
Abrasive wear is a major mechanism that affects the service lives of machines.For the ploughing wear mechanism,the wear debris was modeled respectively with spherical and the likely fractal debris,and abrasive wear was divided into three processes:pressing,sliding and crushing.With the finite element software ANSYS,the Mises stress and shear stress distribution and their changes with the depth of the surface increasing were studied,and analysis results of the two models were compared.The results demonstrate that,in the spherical model,the distribution of Mises stress and shear stress at the contact area between the debris and the contact surface is more dispersed,and the stress peak value is smaller,and neither the abrasive debris nor the contact surface is crushed;however,in the fractal model,the distribution of Mises stress and shear stress at the contact area between the debris and the contact surface is more concentrated,and the corresponding stress peak value is higher,and the debris and the contact surface are both crushed.For the two models,the fractal shape of abrasive particles constructed with fractal method is more similar to the actual shape of the wear debris.
2018, 43(3):42-48.
DOI: 10.3969/j.issn.0254-0150.2018.03.007
Abstract:
To simulate the heat and mass transfer in micronano heterogeneous systems,such as metalproduction processes and lubrication,the point contact condition with the formation of narrowly confined water/oil meniscus was constructed to study the classical micro channel boiling problem.The evaporation and diffusion of the superheated water meniscus and water/oil droplet in the point contact geometry were investigated,and the influence of the contact line transport behaviors on the nucleation and bubble behaviors in the confined meniscus was analyzed.The observations suggest that superheat is the necessary condition for bubble formation and enough vapor supply is the necessary condition for bubble growth in the confined liquid.The oil film can significantly inhibit the evaporation and diffusion of water molecules in the superheat geometry.The water/oil droplet can exist for a long time even in the hot confined space of 200 ℃,which has sustained damages to the mechanical system suffering from water contamination.
To simulate the heat and mass transfer in micronano heterogeneous systems,such as metalproduction processes and lubrication,the point contact condition with the formation of narrowly confined water/oil meniscus was constructed to study the classical micro channel boiling problem.The evaporation and diffusion of the superheated water meniscus and water/oil droplet in the point contact geometry were investigated,and the influence of the contact line transport behaviors on the nucleation and bubble behaviors in the confined meniscus was analyzed.The observations suggest that superheat is the necessary condition for bubble formation and enough vapor supply is the necessary condition for bubble growth in the confined liquid.The oil film can significantly inhibit the evaporation and diffusion of water molecules in the superheat geometry.The water/oil droplet can exist for a long time even in the hot confined space of 200 ℃,which has sustained damages to the mechanical system suffering from water contamination.
2018, 43(3):1-10.
DOI: 10.3969/j.issn.0254-0150.2018.03.001
Abstract:
The state of rubberlike materials aging in different liquid media,such as the lubricants,solvents,fuels and the different types of water vapor environment,was summarized.The experimental and theoretical analyzing methods,the test and analysis techniques,as well as the test and analysis instrument and equipment were presented.The tribological behavior and working life prediction methods of rubberlike materials were given in outline.Combined with the urgent needs of China’s high speed rail,marine engineering equipment and aerospace fields,the major research topics were presented,especially the aging test,tribological & mechanical performance,and life prediction of typical rubberlike materials used in seals in different fluid media.
The state of rubberlike materials aging in different liquid media,such as the lubricants,solvents,fuels and the different types of water vapor environment,was summarized.The experimental and theoretical analyzing methods,the test and analysis techniques,as well as the test and analysis instrument and equipment were presented.The tribological behavior and working life prediction methods of rubberlike materials were given in outline.Combined with the urgent needs of China’s high speed rail,marine engineering equipment and aerospace fields,the major research topics were presented,especially the aging test,tribological & mechanical performance,and life prediction of typical rubberlike materials used in seals in different fluid media.
2018, 43(3):69-74.
DOI: 10.3969/j.issn.0254-0150.2018.03.011
Abstract:
Considering the influence of the heat generation mechanisms by friction and hyperelasticity theory on the temperature field of the rotating shaft lip seal, the temperature distribution of the oil seal under specific working conditions was simulated.The threedimensional finite element model of lip seal was established by using the finite element analysis software ABAQUS.The unsteady temperature field of a lip seal before and after optimization was simulated and the relationship curves between pressure,speed and oil temperature were obtained.The simulation results show that the temperature field distribution of the rotary shaft lip seal before and after optimization satisfies the sealing requirement. In the range of the analyzed parameters,the temperature of the seal ring is decreased with the increasing of the pressure,and increased with the increasing of the rotational speed.The temperature on the friction surface is increased gradually from the two sides to the middle, and the maximum temperature appears at the center close to the air side.The change of temperature of the optimized oil seal tends to be smooth with the increasing of the rotational speed and the pressure,which proves that the optimized oil seal has better sealing performance and heat dissipation performance.
Considering the influence of the heat generation mechanisms by friction and hyperelasticity theory on the temperature field of the rotating shaft lip seal, the temperature distribution of the oil seal under specific working conditions was simulated.The threedimensional finite element model of lip seal was established by using the finite element analysis software ABAQUS.The unsteady temperature field of a lip seal before and after optimization was simulated and the relationship curves between pressure,speed and oil temperature were obtained.The simulation results show that the temperature field distribution of the rotary shaft lip seal before and after optimization satisfies the sealing requirement. In the range of the analyzed parameters,the temperature of the seal ring is decreased with the increasing of the pressure,and increased with the increasing of the rotational speed.The temperature on the friction surface is increased gradually from the two sides to the middle, and the maximum temperature appears at the center close to the air side.The change of temperature of the optimized oil seal tends to be smooth with the increasing of the rotational speed and the pressure,which proves that the optimized oil seal has better sealing performance and heat dissipation performance.
2018, 43(3):23-30.
DOI: 10.3969/j.issn.0254-0150.2018.03.004
Abstract:
Compared with conventional orifice air bearing,porous aerostatic bearings possess many advantages such as higher load capacity,better stability and manufacturing convenience.The effect of the key factors such as eccentricity,porous material permeability,bearing aspect ratio and average film thickness on the static performance of porous aerostatic bearings were analyzed with the commercial software Fluent which was based on finite volume method.The analysis results show that,there is an optimum permeability interval which can make the load capacity maximum under a certain average film thickness.The load capacity and stiffness of the porous air journal bearing can be improved by increasing the bearing aspect ratio and reducing the average film thickness.However,the parameters need to be carefully chosen by taking the requirements of manufacture,assembly and working condition into consideration.New form of centrally air supply porous journal bearing was designed and fabricated,the pressure distribution of gas film was obtained and load capacity was calculated.The validity of simulation results was verified by static performance experiment.The results of simulation and experiment indicate that the porous journal bearing with this structural form has excellent performance.
Compared with conventional orifice air bearing,porous aerostatic bearings possess many advantages such as higher load capacity,better stability and manufacturing convenience.The effect of the key factors such as eccentricity,porous material permeability,bearing aspect ratio and average film thickness on the static performance of porous aerostatic bearings were analyzed with the commercial software Fluent which was based on finite volume method.The analysis results show that,there is an optimum permeability interval which can make the load capacity maximum under a certain average film thickness.The load capacity and stiffness of the porous air journal bearing can be improved by increasing the bearing aspect ratio and reducing the average film thickness.However,the parameters need to be carefully chosen by taking the requirements of manufacture,assembly and working condition into consideration.New form of centrally air supply porous journal bearing was designed and fabricated,the pressure distribution of gas film was obtained and load capacity was calculated.The validity of simulation results was verified by static performance experiment.The results of simulation and experiment indicate that the porous journal bearing with this structural form has excellent performance.
2018, 43(3):129-135.
DOI: 10.3969/j.issn.0254-0150.2018.03.022
Abstract:
Lubrication is one of the core contents of equipment management,the selection,using,monitoring and lubrication management of lubricants must meet the needs of mining machinery features,such as low speed and heavy loading,large temperature difference of environment,easy to be polluted and emulsified.The lubrication management problems existed in mining enterprises were analyzed,and the management mode of lubrication based on reliability theory was proposed.The practice shows that the lubrication idea,network platform and methods can significantly promote the lubrication management and profit.The lubrication management of mining machine rotary equipment based on reliability theory is also an important exploration and application of reliability theory in the production practice.
Lubrication is one of the core contents of equipment management,the selection,using,monitoring and lubrication management of lubricants must meet the needs of mining machinery features,such as low speed and heavy loading,large temperature difference of environment,easy to be polluted and emulsified.The lubrication management problems existed in mining enterprises were analyzed,and the management mode of lubrication based on reliability theory was proposed.The practice shows that the lubrication idea,network platform and methods can significantly promote the lubrication management and profit.The lubrication management of mining machine rotary equipment based on reliability theory is also an important exploration and application of reliability theory in the production practice.
2018, 43(3):104-108.
DOI: 10.3969/j.issn.0254-0150.2018.03.017
Abstract:
A synthetic cutting fluid was prepared and the synergistic effect between organic molybdenum and organoboron extreme pressure agents and triethanolamine borate antirust agent was studied.The tribological properties of synthetic cutting fluid were studied with fourball friction and wear tester;the antirust performance was studied through the sheet rust test and laminated rust test with grey cast iron;the surface morphology of the specimen was observed with a laser confocal microscope,and the surface roughness of the specimen was measured to investigate the influence of extreme pressure agent on the surface quality of the specimen.The results show that two kinds of extreme pressure agents have a synergistic effect,which can increase the extreme pressure lubricating factor(The ratio of the maximum nonseizure load to the friction coefficient) of synthetic cutting fluid,and improve the surface quality of the specimen.The synergistic effect between organoboron extreme pressure agent and triethanolamine borate antirust agent can enhance the antirust effect of the cutting fluid.When adding compound extreme pressure agents and antirust agent in the synthetic cutting fluid,both the extreme pressure performance and the antirust performance are increased compared with a single additive of cutting fluid,indicatingthe compound extreme pressure agents have a synergistic effect with antirust agent.
A synthetic cutting fluid was prepared and the synergistic effect between organic molybdenum and organoboron extreme pressure agents and triethanolamine borate antirust agent was studied.The tribological properties of synthetic cutting fluid were studied with fourball friction and wear tester;the antirust performance was studied through the sheet rust test and laminated rust test with grey cast iron;the surface morphology of the specimen was observed with a laser confocal microscope,and the surface roughness of the specimen was measured to investigate the influence of extreme pressure agent on the surface quality of the specimen.The results show that two kinds of extreme pressure agents have a synergistic effect,which can increase the extreme pressure lubricating factor(The ratio of the maximum nonseizure load to the friction coefficient) of synthetic cutting fluid,and improve the surface quality of the specimen.The synergistic effect between organoboron extreme pressure agent and triethanolamine borate antirust agent can enhance the antirust effect of the cutting fluid.When adding compound extreme pressure agents and antirust agent in the synthetic cutting fluid,both the extreme pressure performance and the antirust performance are increased compared with a single additive of cutting fluid,indicatingthe compound extreme pressure agents have a synergistic effect with antirust agent.
2018, 43(3):136-140.
DOI: 10.3969/j.issn.0254-0150.2018.03.023
Abstract:
The main factors influencing the lubricating properties of waterbased cutting fluid for aluminum alloy processing were studied by the tapping torque test.The results show that pH value of the diluent and the emulsion particle size have the most significant influence on the lubricating properties,and the content of base oil,the types and content of lubricating additives also have obvious effect on the lubricating properties.Furthermore,the diluent with lower pH value,larger particle size,higher content of base oil and synthetic ester presents excellent lubricating properties.The trimethylolpropane,ethoxylated polymeric esters,chlorinated paraffin and sulfurized fatty acid ester are efficient additives of aluminum alloy processing,while sulfurized olefin has poor lubrication property.
The main factors influencing the lubricating properties of waterbased cutting fluid for aluminum alloy processing were studied by the tapping torque test.The results show that pH value of the diluent and the emulsion particle size have the most significant influence on the lubricating properties,and the content of base oil,the types and content of lubricating additives also have obvious effect on the lubricating properties.Furthermore,the diluent with lower pH value,larger particle size,higher content of base oil and synthetic ester presents excellent lubricating properties.The trimethylolpropane,ethoxylated polymeric esters,chlorinated paraffin and sulfurized fatty acid ester are efficient additives of aluminum alloy processing,while sulfurized olefin has poor lubrication property.
9 Effects of Pretightening Force on Response of Displacement Loading of Tightened Bolted Joint Plate
2018, 43(3):75-80.
DOI: 10.3969/j.issn.0254-0150.2018.03.012
Abstract:
The effects of pretightening force on the equivalent stiffness and the critical response of micro and macro sliding of the bolted joint were investigated in order to realize the tightening and reliability of bolted joints.A singlelap single bolted joint plate was used to analyze the relation of contact pressure of joint surfaces and the pretightening forces,its equivalent stiffness model was built by analyzing the characteristic of the displacementloading,a parametric finite element model of the singlelap and single bolted joint plate with a variable pretightening force was developed,and a calculation method of response of displacementloading was proposed.The effects of pretightening force on the response of displacementloading of bolted joint plate at micro sliding phase,as well as the equivalent stiffness and the critical response amplitude of micro and macro sliding were discussed.Results indicate that when the response amplitude of displacementloading of the free end of the bolted joint plate is smaller than 0.075 mm,the pretightening force has no influence on the response of displacementloading,and the equivalent stiffness of the bolted joint plate is getting harder.When the response amplitude of displacementloading is greater than 0075 mm,the pretightening force has obvious influence on equivalent stiffness.There is an approximate linear relationship between the critical response amplitude of micro and macro sliding and the pretightening force.When the pretightening force is \[0.15~0.33\] F0max(F0maxis the maximum pretightening force) or \[0.45 ~ 0.70\] F0max,the pretightening force has less influence on equivalent stiffness,while the effect of pretightening force on the equivalent stiffness reaches to 50%.The conclusions show that the critical response amplitude and the equivalent stiffness of the bolted joint plate can be adjusted by changing the prettightening force.It is very helpful to the design of bolted joint plate by considering both of them.
The effects of pretightening force on the equivalent stiffness and the critical response of micro and macro sliding of the bolted joint were investigated in order to realize the tightening and reliability of bolted joints.A singlelap single bolted joint plate was used to analyze the relation of contact pressure of joint surfaces and the pretightening forces,its equivalent stiffness model was built by analyzing the characteristic of the displacementloading,a parametric finite element model of the singlelap and single bolted joint plate with a variable pretightening force was developed,and a calculation method of response of displacementloading was proposed.The effects of pretightening force on the response of displacementloading of bolted joint plate at micro sliding phase,as well as the equivalent stiffness and the critical response amplitude of micro and macro sliding were discussed.Results indicate that when the response amplitude of displacementloading of the free end of the bolted joint plate is smaller than 0.075 mm,the pretightening force has no influence on the response of displacementloading,and the equivalent stiffness of the bolted joint plate is getting harder.When the response amplitude of displacementloading is greater than 0075 mm,the pretightening force has obvious influence on equivalent stiffness.There is an approximate linear relationship between the critical response amplitude of micro and macro sliding and the pretightening force.When the pretightening force is \[0.15~0.33\] F0max(F0maxis the maximum pretightening force) or \[0.45 ~ 0.70\] F0max,the pretightening force has less influence on equivalent stiffness,while the effect of pretightening force on the equivalent stiffness reaches to 50%.The conclusions show that the critical response amplitude and the equivalent stiffness of the bolted joint plate can be adjusted by changing the prettightening force.It is very helpful to the design of bolted joint plate by considering both of them.
2018, 43(3):62-68.
DOI: 10.3969/j.issn.0254-0150.2018.03.010
Abstract:
The equation of wall slip velocity during lubricating grease pipe flow was established based on HerschelBulkley(HB) rheological model of lubricating grease shear flow,RabinowichMooney equation of wall slip and theoretical model of lubricating grease pipe flow,in order to study the effect of temperature on wall slip of lubricating grease pipe flow.The influence factors and variation for wall slip velocity were analyzed.The rheological properties of lubricating grease from 25 ℃ to 85 ℃ were studied by using rough measuring plate model of rotational rheometer.The parameters of HB rheological model were obtained at various temperatures.Effects of both pipe diameter and pressure gradient on wall slip velocity were investigated based on the results of lubricating grease rheological properties.The improvement effect mechanism of wall slip during lubricating grease pipe flow was illustrated.It is found that the wall slip velocity of grease pipe flow is increased with the increasing of both pipe diameter and pressure gradient,and the wall slip is obviously improved with the increasing of temperature.
The equation of wall slip velocity during lubricating grease pipe flow was established based on HerschelBulkley(HB) rheological model of lubricating grease shear flow,RabinowichMooney equation of wall slip and theoretical model of lubricating grease pipe flow,in order to study the effect of temperature on wall slip of lubricating grease pipe flow.The influence factors and variation for wall slip velocity were analyzed.The rheological properties of lubricating grease from 25 ℃ to 85 ℃ were studied by using rough measuring plate model of rotational rheometer.The parameters of HB rheological model were obtained at various temperatures.Effects of both pipe diameter and pressure gradient on wall slip velocity were investigated based on the results of lubricating grease rheological properties.The improvement effect mechanism of wall slip during lubricating grease pipe flow was illustrated.It is found that the wall slip velocity of grease pipe flow is increased with the increasing of both pipe diameter and pressure gradient,and the wall slip is obviously improved with the increasing of temperature.
2018, 43(3):31-36.
DOI: 10.3969/j.issn.0254-0150.2018.03.005
Abstract:
W-sealing ring is a kind of elastic metallic seal which is used to solve sealing problem in extremely working conditions in aerospace field.A finite element model of Wring was built and its working stress under different states was analyzed.The influencing factors of maximum Von Mises stress and maximum contact stress were explored.The whole loading and unloading process of W-ring under different working states was simulated by using ANSYS and the influencing factors of compression recovery rate were explored.It is found that in the calculation range,the increase in wave thickness and compression displacement causes the increase of maximum contact stress and the improvement of sealing property,and the increase in wave height and temperature causes the decrease of maximum contact stress and sealing property;the increase in wave thickness and compression displacement causes the decrease of compression recovery rate,and the increase in wave height and pressure causes the increase of compression recovery rate.
W-sealing ring is a kind of elastic metallic seal which is used to solve sealing problem in extremely working conditions in aerospace field.A finite element model of Wring was built and its working stress under different states was analyzed.The influencing factors of maximum Von Mises stress and maximum contact stress were explored.The whole loading and unloading process of W-ring under different working states was simulated by using ANSYS and the influencing factors of compression recovery rate were explored.It is found that in the calculation range,the increase in wave thickness and compression displacement causes the increase of maximum contact stress and the improvement of sealing property,and the increase in wave height and temperature causes the decrease of maximum contact stress and sealing property;the increase in wave thickness and compression displacement causes the decrease of compression recovery rate,and the increase in wave height and pressure causes the increase of compression recovery rate.
2018, 43(3):109-112.
DOI: 10.3969/j.issn.0254-0150.2018.03.018
Abstract:
The composition of microemulsion processing and lubricating fluid for aluminum alloy was studied,and the influence of surfactant,cosurfactant on the emulsion stability,and the influence of lubricant additives on the lubricating properties of microemulsion were investigated.Tests were conducted on the developed microemulsion processing and lubricating fluid by using fourball machine and Timken test machine.The result shows that the microemulsion has better lubricating properties.Corrosion tests show that the developed microemulsion has no corrosion to aluminum and aluminum alloys,which meets the need of lubrication for aluminum alloys cutting.
The composition of microemulsion processing and lubricating fluid for aluminum alloy was studied,and the influence of surfactant,cosurfactant on the emulsion stability,and the influence of lubricant additives on the lubricating properties of microemulsion were investigated.Tests were conducted on the developed microemulsion processing and lubricating fluid by using fourball machine and Timken test machine.The result shows that the microemulsion has better lubricating properties.Corrosion tests show that the developed microemulsion has no corrosion to aluminum and aluminum alloys,which meets the need of lubrication for aluminum alloys cutting.
2018, 43(3):49-55.
DOI: 10.3969/j.issn.0254-0150.2018.03.008
Abstract:
A performance analyzing model of Ygroove liquid film seals was established based on mass conserving boundary condition.The universal Reynolds equation was discretized by the finite difference method,and loadcarrying capacity,film stiffness,leakage,friction torque were obtained by solving the discretized equation with the SOR iterative algorithm.The influence of structural parameters of Ygroove liquid film seals on the seal performance were analyzed.The results indicate that the sealing performance is significantly affected by structural parameters,including the number of grooves,groove depth,spiral angle,ratio of groove to ridge width and ratio of groove to groove.With the increasing of these structural parameters,the load-carrying capacity and film stiffness are first increases then decreases,the friction torque is increased.The leakage is first increased then becomes steady with increasing of groove number,first increased then decreased with increasing of ratio of groove to ridge width,and decreased with increasing of ratio of groove to ridge width.The Ygroove liquid film seals have better performance with the parameters in the paper:the number of grooves is from 12 to 14,groove depth is from 35 to 40 μm,spiral angle is from 12° to 16°,ratio of groove to ridge width is from 0.7 to 1.1,and the ratio of groove to groove is from 0.8 to 1.0.
A performance analyzing model of Ygroove liquid film seals was established based on mass conserving boundary condition.The universal Reynolds equation was discretized by the finite difference method,and loadcarrying capacity,film stiffness,leakage,friction torque were obtained by solving the discretized equation with the SOR iterative algorithm.The influence of structural parameters of Ygroove liquid film seals on the seal performance were analyzed.The results indicate that the sealing performance is significantly affected by structural parameters,including the number of grooves,groove depth,spiral angle,ratio of groove to ridge width and ratio of groove to groove.With the increasing of these structural parameters,the load-carrying capacity and film stiffness are first increases then decreases,the friction torque is increased.The leakage is first increased then becomes steady with increasing of groove number,first increased then decreased with increasing of ratio of groove to ridge width,and decreased with increasing of ratio of groove to ridge width.The Ygroove liquid film seals have better performance with the parameters in the paper:the number of grooves is from 12 to 14,groove depth is from 35 to 40 μm,spiral angle is from 12° to 16°,ratio of groove to ridge width is from 0.7 to 1.1,and the ratio of groove to groove is from 0.8 to 1.0.
2018, 43(3):92-97.
DOI: 10.3969/j.issn.0254-0150.2018.03.015
Abstract:
The effect of textured cemented carbide tool on cutting performance in machining of titanium alloy was studied.Experimental research on machining of titanium alloy was carried out to analyze the change laws of cutting force and friction coefficient when cutting by untextured and textured tools under the conditions of dry cutting and cryogenic minimum quantity lubrication(CMQL).Results show that the microgrooved tool has the best cutting performance under CMQL and the worst cutting performance under dry cutting,which indicates that the microgroove can effectively improve the tribological performance of the tool under CMQL,but it increases the friction and wear of the tool under the dry cutting.The cutting temperature of textured tools under high speed dry cutting was analyzed by simulated.It is found that the cutting temperature of textured tools is higher that of untextured tools under high speed dry cutting,this is because the surface texture increases the roughness of the tool surface and aggravates the friction between the cutter and the chip interface.
The effect of textured cemented carbide tool on cutting performance in machining of titanium alloy was studied.Experimental research on machining of titanium alloy was carried out to analyze the change laws of cutting force and friction coefficient when cutting by untextured and textured tools under the conditions of dry cutting and cryogenic minimum quantity lubrication(CMQL).Results show that the microgrooved tool has the best cutting performance under CMQL and the worst cutting performance under dry cutting,which indicates that the microgroove can effectively improve the tribological performance of the tool under CMQL,but it increases the friction and wear of the tool under the dry cutting.The cutting temperature of textured tools under high speed dry cutting was analyzed by simulated.It is found that the cutting temperature of textured tools is higher that of untextured tools under high speed dry cutting,this is because the surface texture increases the roughness of the tool surface and aggravates the friction between the cutter and the chip interface.
15 Effects of Pulse Bias Voltages on Structure and Property of DLC Films Prepared by PECVD Technique
2018, 43(3):17-22.
DOI: 10.3969/j.issn.0254-0150.2018.03.003
Abstract:
The diamondlike carbon (DLC) films were prepared on the surface of 304 stainless steel by plasma enhanced chemical vapor deposition (PECVD) technique with varying pulse bias voltages.The surface roughness,the crosssectional morphology,the structure and composition of the films were characterized by surface profilometer,scanning electron microscopy,Raman spectrum and electron probe,respectively.The hardness and elastic modulus of the films were tested on a nanoindentor,and the corresponding adhesion forces between the film and substrate were investigated using a scratch tester.The tribological properties of the films were evaluated by a ballondisc tribometer.The results show that the DLC films are successfully prepared by PECVD technique and the applied pulsed bias voltages greatly affect the morphologies,microstructures and mechanical properties of the asprepared DLC films.With the increasing of the bias voltages,the surface roughness,friction coefficient and wear rate of the DLC film are decreased to a minimum value and then start to increase,while the adhesion force between the film and the substrate is increased to a maximum value and then slightly decreased.The film prepared with 20 kV pulse bias voltage exhibits optimal adhesion force to the substrate.However,the film prepared with 16 kV bias voltage shows the smoothest surface and the highest hardness,resulting in superior friction reduction and wear resistance.
The diamondlike carbon (DLC) films were prepared on the surface of 304 stainless steel by plasma enhanced chemical vapor deposition (PECVD) technique with varying pulse bias voltages.The surface roughness,the crosssectional morphology,the structure and composition of the films were characterized by surface profilometer,scanning electron microscopy,Raman spectrum and electron probe,respectively.The hardness and elastic modulus of the films were tested on a nanoindentor,and the corresponding adhesion forces between the film and substrate were investigated using a scratch tester.The tribological properties of the films were evaluated by a ballondisc tribometer.The results show that the DLC films are successfully prepared by PECVD technique and the applied pulsed bias voltages greatly affect the morphologies,microstructures and mechanical properties of the asprepared DLC films.With the increasing of the bias voltages,the surface roughness,friction coefficient and wear rate of the DLC film are decreased to a minimum value and then start to increase,while the adhesion force between the film and the substrate is increased to a maximum value and then slightly decreased.The film prepared with 20 kV pulse bias voltage exhibits optimal adhesion force to the substrate.However,the film prepared with 16 kV bias voltage shows the smoothest surface and the highest hardness,resulting in superior friction reduction and wear resistance.
2018, 43(3):123-128.
DOI: 10.3969/j.issn.0254-0150.2018.03.021
Abstract:
The research achievements of various types of extreme pressure and antiwear additives in grease were reviewed.It includes flake,pellet additives,micro nano scale soft,hard point additives,micro nano scale oxide and other compound additives,environmentally friendly additives.The mechanism of antiwear and friction reduction were summarized,and the research direction of extreme pressure and antiwear additives for lubricating greases was put forward according to the existing problems.
The research achievements of various types of extreme pressure and antiwear additives in grease were reviewed.It includes flake,pellet additives,micro nano scale soft,hard point additives,micro nano scale oxide and other compound additives,environmentally friendly additives.The mechanism of antiwear and friction reduction were summarized,and the research direction of extreme pressure and antiwear additives for lubricating greases was put forward according to the existing problems.
2018, 43(3):117-122.
DOI: 10.3969/j.issn.0254-0150.2018.03.020
Abstract:
The solid particles in the oil may cause erosion wear on the wall of pipeline in the process of oil transportation.DPM erosion model was used to predict the erosion area on the tee in different planes by changing the inlet velocity,particle diameter and particle mass flow rate.The results show that the erosion wear of tee in different planes is mainly concentrated on the curved surface in the junction of three pipes,the upper wall of the horizontal pipes and the junction of two horizontal pipes,while the erosion wear on the bottom of pipe bend is smaller.As the inlet velocity increasing,the maximum erosion rate of pipe is increased exponentially.The maximum erosion rate of pipe is firstly increased slowly with the increasing of particle diameter,then increased linearly when the particle diameter is increased to a certain value.With the increase of particle mass flow rate,the maximum erosion rate of pipe is increased linearly.
The solid particles in the oil may cause erosion wear on the wall of pipeline in the process of oil transportation.DPM erosion model was used to predict the erosion area on the tee in different planes by changing the inlet velocity,particle diameter and particle mass flow rate.The results show that the erosion wear of tee in different planes is mainly concentrated on the curved surface in the junction of three pipes,the upper wall of the horizontal pipes and the junction of two horizontal pipes,while the erosion wear on the bottom of pipe bend is smaller.As the inlet velocity increasing,the maximum erosion rate of pipe is increased exponentially.The maximum erosion rate of pipe is firstly increased slowly with the increasing of particle diameter,then increased linearly when the particle diameter is increased to a certain value.With the increase of particle mass flow rate,the maximum erosion rate of pipe is increased linearly.
2018, 43(3):98-103.
DOI: 10.3969/j.issn.0254-0150.2018.03.016
Abstract:
Based on the structure characteristics of bumptype bearing,new bumptype gas foil journal bearings of coupling top foil and bump foil was proposed,including three kinds of gas journal bearings that the foil covers the whole circle,the upper half circle and the lower half circle of the bearing separately.Considering the compressibility of air,the twodimensional gas flow of the bump foil bearing was simulated,the bearing capacity of the foil bearing was analyzed and compared with that of the rigid gas bearing.It is found that the bearing capacity of the bearing with foil covering the lower half circle is optimal.By changing the foil number,foil width and foil height of the bearing with foil covering the lower half circle,the change of the gas membrane flow field was further simulated.The simulation results show that under the condition of satisfying the stability of foil structure,the bearing capacity of the bearing with foil covering the lower half circle is increased with the increasing of the foil number and foil width,and it shows a sharp increase and then a slow decrease with the increasing of the foil height.
Based on the structure characteristics of bumptype bearing,new bumptype gas foil journal bearings of coupling top foil and bump foil was proposed,including three kinds of gas journal bearings that the foil covers the whole circle,the upper half circle and the lower half circle of the bearing separately.Considering the compressibility of air,the twodimensional gas flow of the bump foil bearing was simulated,the bearing capacity of the foil bearing was analyzed and compared with that of the rigid gas bearing.It is found that the bearing capacity of the bearing with foil covering the lower half circle is optimal.By changing the foil number,foil width and foil height of the bearing with foil covering the lower half circle,the change of the gas membrane flow field was further simulated.The simulation results show that under the condition of satisfying the stability of foil structure,the bearing capacity of the bearing with foil covering the lower half circle is increased with the increasing of the foil number and foil width,and it shows a sharp increase and then a slow decrease with the increasing of the foil height.
2018, 43(3):113-116.
DOI: 10.3969/j.issn.0254-0150.2018.03.019
Abstract:
Vacuum separation method can acquire low limit water content and coalescence separation method has a high efficiency in lubricating oil dehydration.By combining with the advantages of the two methods,the coalescencevacuum combination separation method of lubricating oil was put forward.The structure principle and working mode of two kinds of separation devices,the coalescencevacuum series combination separation device and coalescencevacuum integration separation device were introduced.By selecting the LTSA46 turbine oil as the text object,the dewatering performance of two kinds of separation devices was tested and compared.The results show that the dewatering performance of two kinds of separation devices is very close,the dehydration efficiency of the coalescencevacuum series combination separation device is slightly higher than that of coalescencevacuum integrated separation device,howerever,the coalescencevacuum series combination separation device has a larger volume,and the vacuum pump needs to work continuously,so the wear is faster
Vacuum separation method can acquire low limit water content and coalescence separation method has a high efficiency in lubricating oil dehydration.By combining with the advantages of the two methods,the coalescencevacuum combination separation method of lubricating oil was put forward.The structure principle and working mode of two kinds of separation devices,the coalescencevacuum series combination separation device and coalescencevacuum integration separation device were introduced.By selecting the LTSA46 turbine oil as the text object,the dewatering performance of two kinds of separation devices was tested and compared.The results show that the dewatering performance of two kinds of separation devices is very close,the dehydration efficiency of the coalescencevacuum series combination separation device is slightly higher than that of coalescencevacuum integrated separation device,howerever,the coalescencevacuum series combination separation device has a larger volume,and the vacuum pump needs to work continuously,so the wear is faster
