scholarly journals Study on the Biotribological Properties of Ti6Al7Nb and Ultra High Density Molecular Weight Polyethylene at Different Lubricant Temperature

2021 ◽  
Vol 27 (1) ◽  
pp. 111-118
Author(s):  
Songquan WANG ◽  
Ningning HU ◽  
Shuo YANG ◽  
Da HAN ◽  
Deqi SUN ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Mechanism ◽  
Strong Correlation ◽  
Protective Layer ◽  
Frictional Heat ◽  
Precipitation Process ◽  
Wear Loss ◽  
Friction Process ◽  
Adhesion Wear

Higher frictional heat will be produced during the service process of artificial hip joint prosthesis in vivo than natural joint, which would cause the rise of the temperature of synovial fluid and the change of the wear resistance of prosthetic materials. In this work, the biotribological properties of ZrO2/Ti6Al7Nb and ZrO2/UHMWPE pairs at different lubricant temperatures were investigated. The results show that there is a strong correlation between the wettability and average friction coefficient of Ti6Al7Nb, while there is also a strong correlation between the wettability and mass loss of UHMWPE. The wear loss of Ti6Al7Nb and UHMWPE decreases gradually and the friction coefficient increases gradually as the lubricant temperature rises from 20 ℃ to 46 ℃, which is mainly affected by the precipitation process of protein. As a protective layer, it can reduce the wear rate, but as a third body, it can participate in the friction process and increase the friction coefficient. The characteristics of lubricant change greatly at 60 ℃, but the increase of temperature is not the only reason for the precipitation of synovial protein. The synergistic effect with the friction process results in a significant change on the wear mechanism of Ti6Al7Nb and UHMWPE under this condition. The wear mechanism of Ti6Al7Nb is mainly abrasive wear and adhesion wear at different lubricant temperature. With the increase of lubricant temperature, the proportion of adhesion wear mechanism becomes larger. Due to the low thermal deformation temperature and thermal conductivity, the wear mechanism of UHMWPE changed obviously at 60 ℃, and the wear morphology is mainly plastic deformation.

The Effect of Particle Concentration and Magnetic Field on Tribological Behavior of Magneto-Rheological Fluid

2011 ◽  
Vol 314-316 ◽  
pp. 58-61 ◽  
Author(s):  
Wan Li Song ◽  
Chul Hee Lee ◽  
Seung Bok Choi ◽  
Myeong Woo Cho
Keyword(s):  
Magnetic Field ◽  
Friction Coefficient ◽  
Wear Mechanism ◽  
Particle Concentration ◽  
Tribological Behavior ◽  
Wear Loss ◽  
Wear Properties ◽  
Mr Fluid ◽  
Magneto Rheological ◽  
The Magnetic Field

In this paper, the effect of particle concentration and magnetic field on the tribological behavior of magneto-rheological (MR) fluid is investigated using a pin-on-disc tribometer. The wear loss and friction coefficient are measured to study the friction and wear properties of MR fluid. The morphology of the worn pin is also observed by scanning electron microscope (SEM) in order to analyze the wear mechanism. The results obtained in this work show that the wear loss and friction coefficient decrease with increasing particle concentration under the magnetic field. Furthermore, it is demonstrated that the magnetic field has a significant effect on improving tribological properties of MR fluid, especially the one with high particle concentration. The predominant wear mechanism of the MR fluid has been identified as abrasive wear.

scholarly journals Dry Rolling/Sliding Wear of Bainitic Rail Steels under Different Contact Stresses and Slip Ratios

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4678
Author(s):  
Jiapeng Liu ◽  
Yingqi Li ◽  
Yinhua Zhang ◽  
Yue Hu ◽  
Lubing Shi ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Abrasive Wear ◽  
Contact Stress ◽  
Wear Mechanism ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Loss ◽  
Fatigue Wear ◽  
Slip Ratio

This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism.

Wear of Spiral Seal Cone Bit in Complex Formations

SPE Journal ◽  
2021 ◽  
pp. 1-16
Author(s):  
Y. Zhou ◽  
J. H. Hu ◽  
B. Tan ◽  
Y. Jiang ◽  
Y. F. Tang
Keyword(s):  
Friction Coefficient ◽  
Working Conditions ◽  
Wear Mechanism ◽  
Testing Machine ◽  
Wear Test ◽  
Simulation Method ◽  
Wear Testing ◽  
Wear Loss ◽  
Wear Depth ◽  
Wear Properties

Summary Sealing is a technical bottleneck that affects drilling efficiency and cost in deep, difficult-to-drill formations. The spiral combination seal with active sand removal performance is a new type of seal, and the wear mechanism is not clear, resulting in no effective design. In this study, the wear properties of materials were measured by a friction-and-wear testing machine, and the measurement methods and criteria of wear loss and friction coefficient were established. The fitting function of working condition and friction coefficient was studied by fitting regression method. The law of influence of working conditions on friction coefficient and wear amount was determined. The actual wear model and evaluation criteria of wear condition were established by using wear test data and geometric relationship. The relationship among working conditions, contact stress, and wear depth is determined by numerical simulation method, and the wear mechanism of the new seal is revealed, which provides a theoretical basis for its application.

Friction Coefficient and Wear of PEEK-PTFE Hybrid Radial Ball Bearings under Dry Conditions

2021 ◽  
Vol 1020 ◽  
pp. 114-119
Author(s):  
Kazutoshi Hiraki ◽  
Koshiro Mizobe ◽  
Takahiro Matsueda ◽  
Yuji Kashima ◽  
Katsuyuki Kida
Keyword(s):  
Friction Coefficient ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Frictional Heat ◽  
Wear Loss ◽  
Ball Bearings ◽  
Operation Temperature ◽  
Dry Conditions

In this paper, in order to investigate friction coefficient and wear of PEEK-PTFE hybrid radial bearings, rolling contact fatigue tests were performed under radial loads ranging from 93N to 387N at 600rpm in dry conditions. It was found that friction coefficients were 0.013 to 0.032 throughout the tests. Operation temperature followed the change in the friction coefficient, and PEEK-PTFE radial ball bearings exhibited stable performance even though the temperature locally approached 100 °C due to frictional heat. Moreover, wear loss of bearing components excluding alumina balls increased exponentially with increase of load.

Effect of different loads on wear mechanisms of polyether-ether-ketone in normal saline and debris-isolating method

2021 ◽  
pp. 089270572098420
Author(s):  
Tao Zhang ◽  
Dekun Zhang ◽  
Hongtao Liu ◽  
Kai Chen
Keyword(s):  
Friction Coefficient ◽  
Wear Mechanism ◽  
Normal Saline ◽  
Wear Debris ◽  
Load Condition ◽  
Wear Loss ◽  
Wear Particles ◽  
Polyether Ether Ketone ◽  
Lower Load ◽  
Ether Ketone

Polyether-ether-ketone (PEEK) has been proposed as a biocompatible artificial joint material. Wear particles, generated by friction between artificial joints, lead to bone resorption, aseptic loosening, and ultimately, joint failure. The size and morphology of wear particles contain information of friction and wear. Aim to obtain the wear mechanism of PEEK under different loads, this study separated PEEK debris and investigated the mechanism of wear debris and the relationship between wear mechanism and PEEK-debris morphology. An experiment was carried out with a pin-on-plate testing apparatus under different load conditions, with PEEK sliding against XLPE under saline lubrication. A method of isolating PEEK and XLPE debris from 0.9% normal saline at the same time was investigated by low-speed centrifugation. The morphologies of worn surface and wear debris were obtained based on scanning electron microscopy. The results showed that the maximum friction coefficient and minimum wear loss were 0.115 and 0.223 mg at the load of 50 N. The friction coefficient decreased and the wear loss increased with the load increase. This debris-isolation method can effectively isolate PEEK and XLPE particles larger than 200 nm in diameter. More than 96% wear PEEK particles range from 0.1 µm to 10 μm. Compared with the debris generated under the lower load condition, 0.8% more large wear particles with irregular shapes were found at a load of 150 N. The morphology of wear particles is consistent with the wear mechanism.

Study on Fretting Wear Behavior of 40CrNiMoA Steel

2010 ◽  
Vol 139-141 ◽  
pp. 447-451
Author(s):  
Zhu Jun Li
Keyword(s):  
Friction Coefficient ◽  
Abrasive Wear ◽  
Wear Mechanism ◽  
Wear Behavior ◽  
Experimental Results ◽  
Fretting Wear ◽  
Wear Volume ◽  
Volume Increase ◽  
Test Parameters ◽  
Adhesion Wear

This study deals with fretting wear behavior of 40CrNiMoA steel on a SRVⅣoscillating friction and wear tester. The results indicate that with the frequency and load increasing, both the friction coefficient and fretting wear volume increase. With the amplitude increasing, the fretting wear volume increased too, but the effect of amplitude on friction coefficient was not simple positive correlation according to the experimental results. Meanwhile, the fretting wear mechanism is directly related to test frequency, load and amplitude. When they are small, the main fretting wear mechanism is abrasive wear, with these test parameters increasing, the main fretting wear mechanism turns to a combination of abrasive wear and adhesion wear. Based on the experimental results, the anti-fretting wear measures of steel worm gear pairs used in mechanical tracked regulator of tracked vehicle are discussed.

Study on the Tribological Properties of Porous UHMWPE

2011 ◽  
Vol 84-85 ◽  
pp. 534-538
Author(s):  
Gang Wu ◽  
Xian You Zhong ◽  
Hong Ling Qin ◽  
Chun Hua Zhao
Keyword(s):  
Friction Coefficient ◽  
Porous Structure ◽  
Tribological Properties ◽  
Wear Mechanism ◽  
High Viscosity ◽  
Wear Loss ◽  
Hot Press ◽  
Better Than ◽  
Press Molding

Porous UHMWPE were prepared by hot press molding in Metallographic Sample Mounting. The tribological properties of normal UHMWPE and porous UHMWPE were studied under different loads and lubricant on an improved tribological tester. The friction coefficient and wear loss of porous UHMWPE are steady and low under low loads, which attribute to the porous structure and extrusion effect of lubricant in testing. The results also show that the lubricant of BSA is better than that of water by its high viscosity. Among the increasing of loads, friction coefficient and wear loss are enhance rapidly. Serious cutting is the wear mechanism for porous UHMWPE under high loads.

Tribological characterization of all-polymer prosthesis based on multi-directional motion

2021 ◽  
pp. 089270572110286
Author(s):  
Xinyue Zhang ◽  
Dekun Zhang ◽  
Kai Chen ◽  
Handong Xu ◽  
Cunao Feng
Keyword(s):  
Friction Coefficient ◽  
Abrasive Wear ◽  
Wear Mechanism ◽  
Friction And Wear ◽  
Quantitative Relationship ◽  
Motion Path ◽  
Aspect Ratios ◽  
Directional Motion ◽  
Motion Paths ◽  
Prosthesis Material

The complex movement of artificial joints is closely related to the wear mechanism of the prosthesis material, especially for the polymer prosthesis, which is sensitive to motion paths. In this paper, the “soft-soft” all-polymer of XLPE/PEEK are selected to study the influence of motion paths on the friction and wear performance. Based on the periodic characteristics of friction coefficient and wear morphology, this paper reveals the friction and wear mechanism of XLPE/peek under multi-directional motion path, and obtains the quantitative relationship between friction coefficient and the aspect ratios of “∞”-shape motion path, which is of great significance to reveal and analyze the wear mechanism of “soft” all-polymer under multi-directional motion path. The results show that the friction coefficient is affected by the motion paths and have periodicity. Morever, under the multi-directional motion paths, the wear of PEEK are mainly abrasive wear and adhesive wear due to the cross shear effect, while the wear of XLPE is mainly abrasive wear with plastic accumulation. In addition, the friction coefficient is greatly affected the aspect ratios Rs-l of “∞”-shape and loads. Meanwhile, the wear morphologies are greatly affected by the aspect ratios Rs-l of “∞”-shape, but less affected by loads.

scholarly journals Effect of Low Hydroxyapatite Loading Fraction on the Mechanical and Tribological Characteristics of Poly(Methyl Methacrylate) Nanocomposites for Dentures

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 857
Author(s):  
Ahmed Fouly ◽  
Ahmed Mohamed Mahmoud Ibrahim ◽  
El-Sayed M. Sherif ◽  
Ahmed M.R. FathEl-Bab ◽  
A.H. Badran
Keyword(s):  
Friction Coefficient ◽  
Yield Strength ◽  
Methyl Methacrylate ◽  
Weight Fraction ◽  
Tribological Characteristics ◽  
Compressive Yield Strength ◽  
Wear Loss ◽  
Mechanical Mixing ◽  
Poly Methyl Methacrylate ◽  
Mechanical And Tribological Characteristics

Denture base materials need appropriate mechanical and tribological characteristics to endure different stresses inside the mouth. This study investigates the properties of poly(methyl methacrylate) (PMMA) reinforced with different low loading fractions (0, 0.2, 0.4, 0.6, and 0.8 wt.%) of hydroxyapatite (HA) nanoparticles. HA nanoparticles with different loading fractions are homogenously dispersed in the PMMA matrix through mechanical mixing. The resulting density, Compressive Young’s modulus, compressive yield strength, ductility, fracture toughness, and hardness were evaluated experimentally; the friction coefficient and wear were estimated by rubbing the PMMA/HA nanocomposites against stainless steel and PMMA counterparts. A finite element model was built to determine the wear layer thickness and the stress distribution along the nanocomposite surfaces during the friction process. In addition, the wear mechanisms were elucidated via scanning electron microscopy. The results indicate that increasing the concentration of HA nanoparticles increases the stiffness, compressive yield strength, toughness, ductility, and hardness of the PMMA nanocomposite. Moreover, tribological tests show that increasing the nanoparticle weight fraction considerably decreases the friction coefficient and wear loss.

scholarly journals Feasibility of Magnetic Resonance Fingerprinting on Aging MRI Hardware

Tomography ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 10-21
Author(s):  
Brendan Lee Eck ◽  
Kecheng Liu ◽  
Wei-ching Lo ◽  
Yun Jiang ◽  
Vikas Gulani ◽  
...  
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
Coefficient Of Variation ◽  
Strong Correlation ◽  
Advanced Imaging ◽  
Partial Explanation ◽  
In Vivo Experiments ◽  
Percent Difference ◽  
Relevant Range

The purpose of this work is to evaluate the feasibility of performing magnetic resonance fingerprinting (MRF) on older and lower-performance MRI hardware as a means to bring advanced imaging to the aging MRI install base. Phantom and in vivo experiments were performed on a 1.5T Siemens Aera (installed 2015) and 1.5T Siemens Symphony (installed 2002). A 2D spiral MRF sequence for simultaneous T1/T2/M0 mapping was implemented on both scanners with different gradient trajectories to accommodate system specifications. In phantom, for T1/T2 values in a physiologically relevant range (T1: 195–1539 ms; T2: 20–267 ms), scanners had strong correlation (R2 > 0.999) with average absolute percent difference of 8.1% and 10.1%, respectively. Comparison of the two trajectories on the newer scanner showed differences of 2.6% (T1) and 10.9% (T2), suggesting a partial explanation of the observed inter-scanner bias. Inter-scanner agreement was better when the same trajectory was used, with differences of 6.0% (T1) and 4.0% (T2). Intra-scanner coefficient of variation (CV) of T1 and T2 estimates in phantom were <2.0% and in vivo were ≤3.5%. In vivo inter-scanner white matter CV was 4.8% (T1) and 5.1% (T2). White matter measurements on the aging scanner after two months were consistent, with differences of 1.9% (T1) and 3.9% (T2). In conclusion, MRF is feasible on an aging MRI scanner and required only changes to the gradient trajectory.

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