Study on preparation process parameters and tribological properties of porous PI materials

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yanhong Yan ◽  
Chengwen Yang ◽  
Yanfei Zhou ◽  
Wenbin Dong ◽  
Pengjuan Yan ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Process Parameters ◽  
Tribological Properties ◽  
Orthogonal Experiment ◽  
Optimal Combination ◽  
Tribological Test ◽  
Content Type ◽  
Low Load ◽  
Bearing Materials ◽  
Size And Morphology

Purpose Previously, the effect of pore-forming agents on the properties of pore size and morphology was studied. In this paper, we determine the optimal combination of parameters by tensile strength and perform tribological tests with optimal combination of parameters. Design/methodology/approach In this paper, porous polyimide (PI) materials were fabricated using vacuum hot molding technology. The orthogonal experiment was designed to test the mechanical properties of porous PI materials with the process parameters and the content of pore-forming agent as the changing factors. The porous PI oil-bearing materials were obtained by vacuum immersion, and tribological test were carried out. Findings The results showed that porous PI oil-bearing materials are suitable for low-speed and low-load conditions. The actual value of the friction coefficient basically match with the theoretical value of the regression analysis, and the errors of the friction coefficient are within 10% and 3%, respectively, which proves that the method used in the study is feasible for the friction coefficient prediction. Originality/value In this paper, we have produced a new porous oil-bearing material with good tribological properties. This study can effectively predict the friction coefficient of PI porous material.

Tribological and electrical behavior of Cu-based composites with addition of Ti-doped NbSe2 nanoplatelets

2018 ◽  
Vol 70 (3) ◽  
pp. 560-567 ◽  
Author(s):  
Jian Feng Li ◽  
Qin Shi ◽  
HeJun Zhu ◽  
ChenYu Huang ◽  
Shuai Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Friction Coefficient ◽  
Electrical Properties ◽  
Tribological Properties ◽  
Solid State Reaction ◽  
Electrical Contact ◽  
Solid State Reaction Method ◽  
Content Type ◽  
Reaction Method

Purpose This paper aims to clarify the size and morphology of transition metal dichalcogenides has an impact on lubrication performance of Cu-based composites. This study is intended to show that Cu-based electrical contact materials containing Nb0.91Ti0.09Se2 have better electrical and tribological properties than those containing NbSe2. The tribological properties of Cu-based with different Ti-dopped NbSe2 content were also discussed. Design/methodology/approach The NbSe2 and Nb0.91Ti0.09Se2 particles were fabricated by thermal solid state reaction method. The powder metallurgy technique was used to fabricate composites with varying Nb0.91Ti0.09Se2 mass fraction. The phase composition of Cu-based composites was identified by X-ray diffraction, and the morphology of NbSe2/Nb0.91Ti0.09Se2 and the worn surface of composites were characterized by scanning electron microscopy and transmission electron microscopy. In addition, the tribological properties of composites were appraised using a ball-on-disk multi-functional tribometer. The data of friction coefficient and resistivity were analyzed and the corresponding conclusion was drawn. Findings In comparison with the pure copper, Cu-based composites containing Nb0.91Ti0.09Se2/NbSe2 had a lower friction coefficient, illustrating the Nb0.91Ti0.09Se2 with nano-size particles prepared in this work is a perfect choice for the fabrication of excellent electrical contact composites. Compared to composites with NbSe2, composites containing Nb0.91Ti0.09Se2 have better tribological and electrical properties. Research limitations/implications Because of the use of thermal solid state reaction method, the size of NbSe2 and Nb0.91Ti0.09Se2 is relatively large. Therefore, the fabrication of finer particles of Nb0.91Ti0.09Se2 is encouraged. Originality/value In this paper, the authors discuss the tribological and electrical properties of Cu-based composites, and the value of optimum obtained as Nb0.91Ti0.09Se2 content is 15 Wt.%.

scholarly journals Design of Hydraulic Bulging Die for Automobile Torsion Beam and Optimization of Forming Process Parameters

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Kefan Yang ◽  
Youmin Wang ◽  
Kexun Fu
Keyword(s):  
Friction Coefficient ◽  
Process Parameters ◽  
Orthogonal Experiment ◽  
Die Design ◽  
Molding Pressure ◽  
Hydraulic Pressure ◽  
Forming Process ◽  
Torsion Beam ◽  
Supporting Pressure ◽  
Hydraulic Bulging

The hydraulic bulging technology of tubes can provide hollow parts with special-shaped cross sections. Its manufacturing process can effectively improve material utilization and product accuracy and reduce the number and cost of molds. However, the hydraulic bulging process of parts is very complicated. The size of the tube blank, the design of the loading route, and the forming process parameters will have an effect on the molding quality. Closed tubular torsion automobile beam is considered as the research object to study hydraulic bulging die design and optimize forming process parameters. CATIA software is used to design torsion beam product structure and hydraulic bulging die. AMESim software is employed to design hydraulic synchronous control system for cylinders on both sides of the hydraulic bulging die. Mathematical control model is established and verified in Simulink software. DYNAFORM software is applied to conduct numerical simulation of hydraulic expansion. The supporting pressure, molding pressure, friction coefficient, and feeding quantity are taken as orthogonal experiment level factors. Maximum thinning and maximum thickening rates are taken as hydraulic pressure expansion evaluation indexes to complete the orthogonal experiments. Main molding process parameters are analyzed via orthogonal experiment results and optimized by employing the Taguchi method. Optimal hydraulic bulging parameters are obtained as follows: supporting pressure of 20 MPa, molding pressure of 150 MPa, feeding quantity of 25 mm, and friction coefficient of 0.075. Simulation analysis results indicate that the maximum thinning rate is equal to 9.013%, while the maximum thickening rate is equal to 16.523%. Finally, the design of hydraulic bulging die for torsion beam was completed, and its forming process parameters were optimized.

Behavior evaluation and effects of different lubricants in ECAP process

2017 ◽  
Vol 69 (5) ◽  
pp. 701-707
Author(s):  
Seyed Husein Hasani Najafabadi ◽  
Ali Akbar Lotfi Neyestanak ◽  
Saeed Daneshmand
Keyword(s):  
Friction Coefficient ◽  
Process Parameters ◽  
Effective Strain ◽  
Mesh Size ◽  
Industrial Applications ◽  
Zinc Stearate ◽  
Content Type ◽  
Practical Applications ◽  
Angular Pressing ◽  
Ecap Process

Purpose The purpose of equal channel angular pressing (ECAP) is producing ultra-fine grain materials. In practical applications, it is important to understand and predict effect of different process parameters on deformed parts. One of the most important process parameters is friction coefficient. Behavior evaluation of different lubricants in the ECAP process is the aim of this research. Design/methodology/approach The present study concerns the experimental measurements of the effective strain by means of gridded parts for three different lubricants, graphite, molybdenum disulfide and zinc stearate, to evaluate friction coefficient in ECAP process. Mesh size was 2 × 2 mm2 and embedded in parts made of AL2024; process was done in ambient temperature, and parts were in annealed situation. After the process, strain measured by optical and analytical methods for evaluation of lubricants’ behavior with different friction coefficients. Findings This study shows that zinc stearate has better effects rather than other lubricants in ECAP process and ECAPed parts. Originality/value The fatal challenge for researchers and industrial applications of ECAP process is lubrication. This research is a guide for scientists and engineers (in the future applications) to reduce and control bad frictional effects, produce better parts (more strain homogenous parts), prevent die failures and decrease press tonnage in ECAP process.

The size effect of hexagonal texture on tribological properties under mixed lubrication

2018 ◽  
Vol 70 (9) ◽  
pp. 1798-1805 ◽  
Author(s):  
Long Zheng ◽  
Yihang Gao ◽  
Yinghui Zhong ◽  
Guolong Lu ◽  
Zhenning Liu ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Size Effect ◽  
Tribological Properties ◽  
Equivalent Stress ◽  
Mixed Lubrication ◽  
Groove Width ◽  
Area Density ◽  
Content Type ◽  
Simulated Distribution ◽  
Similar Area

Purpose The purpose of this study is to elucidate the size effect (groove width, unit length and area density) of the hexagonal texture on tribological properties under lubrication. Design/methodology/approach The tribological properties of nine hexagonal textures with different hexagon lengths and groove widths have been investigated under mixed lubrication to elucidate the size effect. Findings Overall, the friction coefficient decreases as the groove width increases within the examined range, whereas the hexagon length shows an optimal value around 3 mm. In particular, one hexagonal texture (3 × 3 mm) exhibits lower friction coefficients and less wear losses than the others. Interestingly, two hexagonal textures of similar area density (1 × 1 mm and 3 × 3 mm) yield the worst and best tribological performances, respectively, which can be explained by the simulated distribution of equivalent stress. Originality/value The tribological properties of nine hexagonal textures are examined under lubrication. The 3 × 3 texture exhibits lower friction coefficient and wear loss than the others. Two textures of similar area density yield the worst and best tribological performances. The results agree with the simulated distribution of equivalent stress.

Study on the influence of round pits arrangement patterns on tribological properties of journal bearings

2019 ◽  
Vol 71 (7) ◽  
pp. 931-941 ◽  
Author(s):  
Yazhou Mao ◽  
Yang Jianxi ◽  
Xu Wenjing ◽  
Liu Yonggang
Keyword(s):  
Friction Coefficient ◽  
Markov Model ◽  
Tribological Properties ◽  
Wear Mechanism ◽  
Friction And Wear ◽  
Journal Bearing ◽  
Energy Dispersive ◽  
Content Type ◽  
Tribological Behaviors ◽  
Bearing Contact

Purpose The purpose of this paper is to investigate the effect of round pits arrangement patterns on tribological properties of journal bearing. In this paper, the tribological behaviors of journal bearing with different arrangement patterns under lubrication condition were studied based on M-2000 friction and wear tester. Design/methodology/approach The friction and wear of journal bearing contact surface were simulated by ANSYS. The wear mechanism of bearing contact surfaces was investigated by the means of energy dispersive spectrum analysis on the surface morphology and friction and wear status of the journal bearing specimens by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). Besides, the wearing capacity of the textured bearing was predicted by using the GM (1,1) and Grey–Markov model. Findings As the loads increase, the friction coefficient of journal bearing specimens decrease first and then increase slowly. The higher rotation speed, the lower friction coefficient and the faster temperature build-up. The main friction method of the bearing sample is three-body friction. The existence of texture can effectively reduce friction and wear. In many arrangement patterns, the best is 4# bearing with round pits cross-arrangement pattern. Its texturing diameters are 60 µm and 125 µm, and the spacing and depth are 200 µm and 25 µm, respectively. In addition, the Grey–Markov model prediction result is more accurate and fit the experimental value better. Originality/value The friction and wear mechanism is helpful for scientific research and engineers to understand the tribological behaviors and engineering applications of textured bearing. The wear capacity of textured bearing is predicted by using the Grey–Markov model, which provides technical help and theoretical guidance for the service life and reliability of textured bearing.

Tribological characterization on friction brake in continuous braking

2018 ◽  
Vol 70 (1) ◽  
pp. 172-181 ◽  
Author(s):  
Jiusheng Bao ◽  
Yan Yin ◽  
Lijian Lu ◽  
Tonggang Liu
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Temperature Rise ◽  
Characteristic Parameter ◽  
Tribological Characteristic ◽  
Content Type ◽  
Average Temperature ◽  
Trend Coefficient ◽  
Dynamic Wear

Purpose The purpose of this study is to establish an effective method for characterizing the tribological properties of friction brakes during continuous braking because they have direct influences on the reliable operation of transport vehicles and industrial equipments. Design/methodology/approach First, tribological tests were carried out with the X-DM type friction tester, and changing curves of friction coefficient and temperature were obtained. Second, a novel tribological characteristic parameter set characterizing the tribological properties of brake pair in continuous braking was extracted from some important experimental data such as friction coefficient, wear rate and temperature. Finally, the influence of law and mechanism of braking number on dynamic tribological parameters was studied through continuous braking experiments. Findings The extracted tribological characteristic parameter set includes two subsets: dynamic characteristic parameter subset and overall characteristic parameter subset, which is composed of ten parameters: dynamic parameters of friction coefficient (including average, trend coefficient and stability coefficient), dynamic wear rate, dynamic average temperature, dynamic temperature rise, overall average friction coefficient, overall wear rate, overall average temperature and overall temperature rise. Originality/value Conclusively, the novel tribological characteristic parameter set is more comprehensive and objective, and it can provide a theoretical basis for the study of tribological properties in continuous braking.

Enhancing the wear resistance of WC–Co cutting inserts using synthetic diamond coatings

2018 ◽  
Vol 70 (7) ◽  
pp. 1224-1233 ◽  
Author(s):  
Kaleem Ahmad Najar ◽  
N.A. Sheikh ◽  
Mohammad Mursaleen Butt ◽  
M.A. Shah
Keyword(s):  
Friction Coefficient ◽  
Tribological Properties ◽  
Synthetic Diamond ◽  
Cutting Tools ◽  
Tribological Characteristics ◽  
Diamond Coating ◽  
Diamond Coatings ◽  
Content Type ◽  
Mechanical And Tribological Properties ◽  
Mechanical And Tribological Characteristics

Purpose The purpose of this study is to investigate the mechanical and tribological properties of the synthetic diamond coatings deposited on WC-Co cutting tools for their prospective applications in mechanical industry. In this work, the concept of nanocrystalline diamond, microcrystalline diamond and multilayer-diamond coating systems were proposed and deposited on WC-Co substrates with the top-layer nanocrystallinity, optimum thickness and interfacial adhesion strength for load-bearing tribological and machining applications. Also, the overall mechanical and tribological properties of all synthetic diamond coatings were compared for the purpose of selecting a suitable type of protective layer used on the surfaces of WC-Co cutting tools or mechanical dies. Design/methodology/approach Smooth and adhesive single layered and multilayered synthetic deposited on chemically etched cemented tungsten carbide (WC-Co) substrates using predetermined process parameters in hot filament chemical vapor deposition (HFCVD) method. A comparison has been documented between diamond coatings having different nature and architecture for the purpose of studying their mechanical and tribological characteristics. The friction characteristics were studied experimentally using ball-on-disc type linear reciprocating micro-tribometer under the influence of varying load conditions and within dry sliding conditions. Nanoindentation tests were conducted on each diamond coating using Berkovich nanoindenter for the measurement of their hardness and elastic modulus values. Also, the wear characteristics of all sliding bodies were studied under varying load conditions using cumulative weight loss and density method. Findings Depositing any type of diamond coating on the cemented carbide tool insert increases its all mechanical and tribological characteristics. When using boron-doping onto the top-layer surface of diamond coatings decrease slightly their mechanical properties but increases the tribological characteristics. Present analysis reveals that friction coefficient of all diamond-coated WC-Co substrates decreases with the increase of normal load. Therefore, maintaining an appropriate level of normal load, sliding time, sliding distance, atmospheric conditions and type of diamond coating, the friction coefficient may be kept to some lower value to improve mechanical processes. Originality/value As the single layered synthetic diamond coatings have not given the full requirements of mechanical and tribological properties when deposited on cutting tools. Therefore, the multilayered diamond coatings were proposed and developed to enhance the interfacial integrity of the nanocrystalline and microcrystalline layers (by eliminating the sharp interface) as well as increasing the hardness of tungsten carbide substrate. However, when using boron doping onto the top-layer surface of diamond, coatings decreases slightly their mechanical characteristics but also decreases the value of friction coefficient.

Effect of laser surface texturing on tribological properties of polyimide composites in the application of traveling wave rotary ultrasonic motor

2018 ◽  
Vol 70 (4) ◽  
pp. 569-577 ◽  
Author(s):  
Xiaoliang Liu ◽  
Gai Zhao ◽  
Jinhao Qiu
Keyword(s):  
Friction Coefficient ◽  
Tribological Properties ◽  
Traveling Wave ◽  
Surface Texturing ◽  
Ultrasonic Motor ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Content Type ◽  
Output Performance ◽  
Polyimide Composites

Purpose The purpose of this paper is to investigate the effect of laser surface texturing on the tribological properties of polyimide composites and the output performance of traveling wave rotary ultrasonic motor. Design/methodology/approach The surface texturing on polyimide composites specimens were fabricated by laser ablation process of different dimple densities, and then the tribological properties were tested by a flat-on-flat tribometer under dry conditions. Finally, the output performance of the traveling wave rotary ultrasonic motor was tested to verify the effectiveness of dimples surface texturing. Findings The results show that surface texturing can greatly enhance the friction coefficient of contact interface, especially the specimen with a dimple density of 7.06 per cent exhibited the highest friction coefficient among the specimens. When the input voltage is 500 V, the output power, locked-rotor torque and output torque of ultrasonic motor with textured PI of 7.06 per cent dimple density as friction material at the speed of 100 r/min increased by 13.8, 19 and 12.8 per cent compared to that of the untextured PTFE, respectively. When the ultrasonic motor reverses, the output performance is increased by 20.9, 40.3 and 17.7 per cent, respectively. Originality/value Surface texturing is an effective way to improve the friction behavior of polyimide composites and then correspondingly enhance the energy conversion efficiency and output performance of the traveling wave rotary ultrasonic motor.

The tribological properties of bulk Fe2B with pre-oxidation treatment at 750°C in air

2019 ◽  
Vol 72 (1) ◽  
pp. 151-156
Author(s):  
Kemin Li ◽  
Zhifu Huang ◽  
Hanwen Ma ◽  
Shaofei Wang ◽  
Chaofeng Qin ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Abrasive Wear ◽  
Oxide Layer ◽  
Tribological Properties ◽  
Wear Mechanisms ◽  
Design Methodology ◽  
Sample Surface ◽  
Oxidation Treatment ◽  
Soaking Time ◽  
Content Type

Purpose The purpose of this study was to investigate the tribological properties of bulk Fe2B with pre-oxidation treatment. Design/methodology/approach Bulk Fe2B was oxidized in an electric box furnace with a soaking time of 9 min under 750°C in air. Then, the tribological experiments were carried out on an UMT-Tribolab tester. Findings The oxide layer was composed of Fe, Fe2O3, Fe3O4, B2O3 and H3BO3. The oxidative direction of bulk Fe2B was perpendicular to the sample surface. But, the oxidative direction of Fe2B crystals was irregular. At 0.1 m/s, the friction coefficient was the lowest. The effects of shortening the running-in period of friction and reducing the friction coefficient by pre-oxidation treatment at 0.1 m/s were remarkable. Nevertheless, the effect of pre-oxidation treatment was futile at 0.2 m/s. Wear mechanisms of oxidized Fe2B mainly were adhesive and abrasive wear. Originality/value The effects of shortening the running-in period of friction and reducing the friction coefficient by pre-oxidation treatment were remarkable.

Biodegradation behavior and tribological properties of ultrahigh molecular weight polyethylene stabilized with α-tocopherol

2019 ◽  
Vol 71 (3) ◽  
pp. 494-498
Author(s):  
Xueqin Kang ◽  
Chi Yao ◽  
Shirong Ge
Keyword(s):  
Molecular Weight ◽  
Tribological Properties ◽  
Design Methodology ◽  
Experimental Studies ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Tribological Test ◽  
Pressing Method ◽  
Content Type ◽  
Ultrahigh Molecular Weight ◽  
One Year

Purpose This paper aims to investigate the effect of simulated body fluid (SBF) on biodegradation and tribological properties of ultrahigh molecular weight polyethylene (UHMWPE) and UHMWPE stabilized with α-tocopherol. Design/methodology/approach The samples of UHMWPE and UHMWPE stabilized with α-tocopherol were prepared by a hot-pressing method, and then immersed in SBF for one year. Tribological test was performed on a UMT-2 tribometer. Findings The crystallinity and tribological properties increased slightly after UHMWPE stabilized with α-tocopherol, whereas the O/C ration decreased slightly. The crystallinity and O/C ratio increased after all samples immersed in SBF for one year. This resulted in the deterioration of tribological properties and the wear mechanism change. The tribological properties change was smaller in UHMWPE stabilized with α-tocopherol than that in UHMWPE, because the oxidation resistance of UHMWPE was increased by α-tocopherol. Originality/value The results of the experimental studies demonstrated and compared the biodegradation behavior and tribological properties of UHMWPE, UHMWPE stabilized with α-tocopherol, and after they immersed in SBF for one year.

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