Defect Structures in Diamond Composite Coated Cemented Tungsten CarbideSubstrates

2011 ◽  
Vol 325 ◽  
pp. 339-344 ◽  
Author(s):  
Jim N. Boland ◽  
Xing S. Li ◽  
D. Hay ◽  
Colin M. MacRae ◽  
S. Elbracht ◽  
...  
Keyword(s):  
Wear Rate ◽  
Poor Quality ◽  
Wear Testing ◽  
Grinding Wheel ◽  
Sem Images ◽  
Volume Percentage ◽  
X Ray ◽  
Wear Rates ◽  
Valid Test ◽  
The Difference

Variability in the abrasive wear of PCD coatings on cemented WC substrates has been investigated. Six samples of PCD coated carbides were tested in a wear testing rig. The PCD coated element was used to turn an industry standard vitrified bonded corundum grinding wheel. The wear rate was measured as the weight loss of the cutting element per cubic metre of grinding wheel machined during the test. Two grades of cutting elements were observed. One grade had wear rates between 6 and 7.3 g/m³ but of the three poor quality samples, only one valid test was made realising wear rate of ~7,800 g/m³. The microstructures of the samples were studied using SEM, X-ray imaging, neutron diffraction and XRD. SEM images revealed differences in the volume percentage of diamonds in the two grades and the XRD scans highlighted the variable distribution of the diamond phase in the coating. Estimates of the residual stresses in a good and poor quality samples indicated significantly higher compressive stresses in the good quality versus poor quality coating. These results have revealed two extremes in the wear rates of these PCD coated carbides. It is suggested that the difference in diamond content between the two grades is not sufficient to account for the 3 orders-of-magnitude difference in the observed wear rates. However, the presence of intrusive veins of carbide material in the coatings, especially around the curved cutting tip, suggested that the macroscopic defects observed in the x-ray and SEM images were the major cause of the high wear rates in the poor quality sample.

scholarly journals Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 53
Author(s):  
Spencer Fullam ◽  
Jade He ◽  
Caroline S. Scholl ◽  
Thomas M. Schmid ◽  
Markus A. Wimmer
Keyword(s):  
Fatty Acid ◽  
Wear Rate ◽  
Conformational Change ◽  
Total Joint Replacement ◽  
Calf Serum ◽  
Competitive Binding ◽  
Wear Testing ◽  
Molar Ratio ◽  
Wear Rates ◽  
Uhmwpe Wear

Total Joint Replacement (TJR) devices undergo standardized wear testing in mechanical simulators while submerged in a proteinaceous testing solution to mimic the environmental conditions of artificial joints in the human body. Typically, bovine calf serum is used to provide the required protein content. However, due to lot-to-lot variability, an undesirable variance in testing outcome is observed. Based on an earlier finding that yellowish-orange serum color saturation is associated with wear rate, we examined potential sources of this variability, by running a comparative wear test with bilirubin; hemin; and a fatty acid, oleic acid, in the lubricant. All these compounds readily bind to albumin, the most abundant protein in bovine serum. Ultrahigh molecular weight polyethylene (UHMWPE) pins were articulated against CoCrMo discs in a pin-on-disc tribometer, and the UHMWPE wear rates were compared between lubricants. We found that the addition of bilirubin increased wear by 121%, while hemin had a much weaker, insignificant effect. When added at the same molar ratio as bilirubin, the fatty acid tended to reduce wear. Additionally, there was a significant interaction with respect to bilirubin and hemin in that UHMWPE wear rate decreased with increasing fatty acid concentration. We believe the conformational change in albumin by binding bilirubin makes it more likely to form molecular bridges between UHMWPE and the metal counterface, thus increasing adhesive wear. However, fatty acids compete for binding sites on albumin, and can prevent this conformational change. Hence, the protein is stabilized, and the chance for albumin to form bridges is lowered. Ultimately, UHMWPE wear rate is driven by the competitive binding of bilirubin and fatty acid to albumin.

The effect of femoral head diameter upon lubrication and wear of metal-on-metal total hip replacements

2001 ◽  
Vol 215 (2) ◽  
pp. 161-170 ◽  
Author(s):  
S L Smith ◽  
D Dowson ◽  
A A J Goldsmith
Keyword(s):  
Wear Rate ◽  
Boundary Lubrication ◽  
Wear Testing ◽  
Wear Rates ◽  
Surface Separation ◽  
Lubricating Film ◽  
Lubrication Regime ◽  
Metal On Metal ◽  
The Mean ◽  
Mixed Lubrication Regime

It has been found that a remarkable reduction in the wear of metal-on-metal hip joints can be achieved by simply increasing the diameter of the joint. A tribological evaluation of metal-on-metal joints of 16, 22,225, 28 and 36 mm diameter was conducted in 25 per cent bovine serum using a hip joint simulator. The joints were subject to dynamic motion and loading cycles simulating walking for both lubrication and wear studies. For each size of joint in the lubrication study, an electrical resistivity technique was used to detect the extent of surface separation through a complete walking cycle. Wear of each size of joint was measured gravimetrically in wear tests of at least 2 × 106 cycles duration. Joints of 16 and 22.225mm diameter showed no surface separation in the lubrication study. This suggested that wear would be proportional to the sliding distance and hence joint size in this boundary lubrication regime. A 28 mm diameter joint showed only limited evidence of surface separation suggesting that these joints were operating in a mixed lubrication regime. A 36 mm diameter joint showed surface separation for considerable parts of each walking cycle and hence evidence of the formation of a protective lubricating film. Wear testing of 16 and 22.225mm diameter metal-on-metal joints gave mean wear rates of 4.85 and 6.30mm3/106 cycles respectively. The ratio of these wear rates, 0.77, is approximately the same as the joint diameters ratio, 16/22.225 or 0.72, as expected from simple wear theory for dry or boundary lubrication conditions. No bedding-in was observed with these smaller diameter joints. For the 28 mm diameter joint, from 0 to 2 × 106 cycles, the mean wear rate was 1.62 mm3/106 cycles as the joints bedded-in. Following bedding-in, from 2.0 × 106 to 4.7 × 106 cycles, the wear rate was 0.54mm3/106 cycles. As reported previously by Goldsmith in 2000 [1], the mean steady state wear rate of the 36 mm diameter joints was lower than those of all the other diameters at 0.07 mm3/106 cycles. For a range of joints of various diameters, subjected to identical test conditions, mean wear rates differed by almost two orders of magnitude. This study has demonstrated that the application of sound tribological principles to prosthetic design can reduce the wear of metal-on-metal joints, using currently available materials, to a negligible level.

The Development of Nanocrystalline CBN for Enhanced Superalloy Grinding Performance

1997 ◽  
Vol 119 (1) ◽  
pp. 110-117 ◽  
Author(s):  
Y. Ichida ◽  
K. Kishi
Keyword(s):  
Wear Rate ◽  
Grinding Wheel ◽  
Grinding Wheels ◽  
Wear Rates ◽  
Grinding Performance ◽  
Wide Range ◽  
Edge Distribution ◽  
Order Of Magnitude ◽  
Life Analysis ◽  
Magnitude Increase

CBN grinding wheels are increasingly used on a wide range of engineering materials. This paper compares the grinding performance of monocrystalline (M-CBN) and polycrystalline (P-CBN) abrasives with a newly developed nanocrystalline (N-CBN) abrasive, when grinding nickel-based superalloys. The N-CBN grits possess average crystal grain diameters less than 1 μm compared to average primary grain diameters of 2.3 μm for P-CBN. It was found that the nanocrystalline CBN grits possess higher fracture strength which give reduced wear rates and yield an order of magnitude increase in grinding wheel life. Analysis of the cutting edge distribution shows that the reduced wear rate of N-CBN is due to the predominance of a micro-fracturing mode of abrasive wear. The size of this micro-fracturing is considerably smaller in N-CBN than in P-CBN.

The Effect of Motion Path on the Wear Rate of UHMWPE for Orthopaedic Implants

1999 ◽  
Author(s):  
Jeff A. Sprague ◽  
Willard L. Sauer
Keyword(s):  
Wear Rate ◽  
Wear Test ◽  
Axial Rotation ◽  
Wear Testing ◽  
Motion Path ◽  
Orthopaedic Implant ◽  
Wear Rates ◽  
Nonlinear Motion ◽  
Pin On Disk

Abstract The effect of adding a second axis of motion was investigated for pin-on-disk wear testing of ultra-high-molecular-weight polyethylene (UHMWPE) for orthopaedic implant applications. In addition to linear reciprocation of the UHMWPE or metal disk, axial rotation of the metal or UHMWPE pin was conducted. The added rotation reproduces the cross-shear on the UHMWPE surface that is generated in clinically relevant wear simulator tests and in vivo. The wear rates that result from the multi-axis pin-on-disk tests are significantly higher (one to two orders of magnitude) than those seen in the linear-only tests. This supports the findings of other researchers (Bragdon et al., 1996; McKellop, 1995; Walker et al., 1996; Wang et al. 1997) in that the application of nonlinear motion increases the wear of UHMWPE substantially. This is further validated by the comparison of a hip simulator wear test conducted with three axes of motion — rotation, flexion, and abduction — to a test conducted with two axes of motion — rotation and flexion. The absence of the abduction eliminated a significant degree of nonlinear motion (cross-shear) and, consequently, the wear rate was significantly lower than that seen in the test with abduction.

Wear Evaluation of Ultra High Molecular Weight Polyethylene Using Pin-On-Flat and Hip Simulation Techniques

1995 ◽  
Vol 394 ◽  
Author(s):  
David W. Schroeder ◽  
Joel C. Higgins
Keyword(s):  
Wear Debris ◽  
Compression Molding ◽  
Wear Testing ◽  
Bacterial Degradation ◽  
Wear Rates ◽  
Hip Simulator ◽  
The Difference ◽  
Wear Evaluation ◽  
Isostatic Compression

AbstractReduction of wear and wear debris is one of the most important areas of research presently in the field of orthopedic devices. It is speculated that wear debris is one of the contributing factors in the cascade of events that lead to osteolysis. In this regard it is very important to be able to evaluate in vitro the wear of UHMWPE produced by various manufacturing methods. Presently the three most common methods of wear testing are: pin-on-flat, pin-on-disk, and hip simulator.Wear evaluation was performed on gamma irradiated UHMWPE that was manufactured by three different processes: extrusion, direct compression molding, and isostatic compression molding. The wear evaluation consisted of pin-on-flat and hip simulator testing.omparison of the results from these two different types of tests show that the two tests would rank the wear resistance of the UHMWPE in the same order. However, there is a variation in the difference of the wear rates between the two tests. The pin-on-flat results show that the direct and isostatic compression molded material had approximately 50% less wear than the extruded material whereas the hip simulator results show that the isostatic compression molded material had 16% less wear than the extruded material. The difference in the results of these two tests are the effects of a combination of factors including the mechanical and material properties of the UHN4WPE, modes of wear that are active, the state of stress (constant vs. cyclic) in the specimens, third body contamination of the lubricant, bacterial degradation of the bovine serum lubricant, etc. Both tests are very important and necessary in the evaluation of wear of orthopedic materials.

Wear simulation of the ProDisc-L disc replacement using adaptive finite element analysis

2007 ◽  
Vol 7 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Jeremy J. Rawlinson ◽  
Karan P. Punga ◽  
Kirk L. Gunsallus ◽  
Donald L. Bartel ◽  
Timothy M. Wright
Keyword(s):  
Finite Element ◽  
Wear Rate ◽  
Axial Load ◽  
Computational Simulation ◽  
Wear Test ◽  
Wear Testing ◽  
Adaptive Finite Element ◽  
Wear Rates ◽  
Specific Loading ◽  
Flexion Extension

Object. An understanding of the wear potential of total disc replacements (TDRs) is critical as these new devices are increasingly introduced into clinical practice. The authors analyzed the wear potential of a ProDisc-L implant using an adaptive finite element (FE) technique in a computational simulation representing a physical wear test. Methods. The framework for calculating abrasive wear, first validated using a model of a total hip replacement (THR), was then used to model the ProDisc-L polyethylene component that is fixed to the inferior endplate and articulates with the rigid superior endplate. Proposed standards for spine wear testing protocols specified the inputs of flexion–extension (6/−3°), lateral bending (± 2°), axial twist (± 1.5°), and axial load (200–1750 N or 600–2000 N) applied to the model through 10 million simulation cycles. The model was calibrated with a wear coefficient determined from an experimental wear test. Implicit FE analyses were then performed for variations in coefficient of friction, polyethylene elastic modulus, radial clearance, and polyethylene component thickness to investigate their effects on wear. Results. Using the initial loading protocol (single-peaked axial load profile of 300–1750 N) from the experimental wear test, the polyethylene wear rate was 9.82 mg per million cycles. When a double-peaked loading profile (600–2000 N) was applied, the wear rate increased to 11.77 mg per million cycles. Parametric design variations produced only small changes in wear rates for this simulation. Conclusions. The chosen design variables had little effect on the resultant wear rates. The comparable wear rate for the THR validation analysis was 16.17 mg per million cycles, indicating that, using this framework, the wear potential of the TDR was equivalent to, if not better, than the THR using joint-specific loading standards.

scholarly journals Microstructure and Wear Properties of Laser Cladding WC/Ni-Based Composite Layer on Al–Si Alloy

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5288
Author(s):  
Xiaoquan Wu ◽  
Daoda Zhang ◽  
Zhi Hu
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Laser Cladding ◽  
Energy Dispersive Spectrometer ◽  
Composite Layer ◽  
Wear Testing ◽  
X Ray Diffraction ◽  
Wear Properties ◽  
X Ray ◽  
Original Specimen

The microstructural and wear properties of laser-cladding WC/Ni-based layer on Al–Si alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and wear-testing. The results show that, compared with the original specimen, the microhardness and wear resistance of the cladding layer on an Al–Si alloy were remarkably improved, wherein the microhardness of the layer achieved 1100 HV and the average friction coefficient of the layer was barely 0.14. The mainly contributor to such significant improvement was the generation of a WC/Ni-composite layer of Al–Si alloy during laser cladding. Two types of carbides, identified as M7C3 and M23C6, were found in the layer. The wear rate of the layer first increased and then decreased with the increase in load; when the load was 20 N, 60 N and 80 N, the wear rate of layer was1.89 × 10−3 mm3·m−1, 3.73 × 10−3 mm3·m−1 and 2.63 × 10−3 mm3·m−1, respectively, and the average friction coefficient (0.14) was the smallest when the load was 60 N.

An Investigation of the Thermal Sprayed Molybdenum Coatings Behaviour to Micro-Abrasion Wear

2016 ◽  
Vol 841 ◽  
pp. 15-20
Author(s):  
Gheorghe Matache ◽  
Alexandru Paraschiv ◽  
Cristian Puscasu
Keyword(s):  
Experimental Data ◽  
Wear Rate ◽  
Electric Arc ◽  
Wear Testing ◽  
Wear Behaviour ◽  
Small Scale ◽  
Wear Rates ◽  
Wear Mode ◽  
Three Body Abrasion ◽  
Three Body

The wear behaviour of thick molybdenum coatings deposited by electric arc thermal spray on steel support was investigated by micro-abrasion, a relatively recent introduced method for small scale wear testing. The wear mechanisms and wear rates without coatings penetration were investigated with respect of time corresponding to primary and secondary wear stages. The micro-abrasion of Mo coatings using SiC abrasive slurry have been discussed and wear scar characteristics were evaluated based on the experimentally results. The worn surfaces of the tested specimen were examined by SEM and the specific wear rate was calculated from experimental data. For the testing durations used it was identified the change from grooving to rolling wear corresponding to the transition of wear mode from two-body to three body-abrasion.

Wear of Artificial Joint Materials III

1981 ◽  
Vol 10 (3) ◽  
pp. 137-142 ◽  
Author(s):  
R W Treharne ◽  
R W Young ◽  
S R Young
Keyword(s):  
Wear Rate ◽  
Contact Area ◽  
Inverse Relationship ◽  
Wear Testing ◽  
Artificial Joint ◽  
Knee Prostheses ◽  
Wear Rates ◽  
Knee Simulator ◽  
Total Knee

This paper describes a new method for testing total knee prostheses under simulated in vivo conditions. Previous knee simulator work has been summarized and described. The major variables of testing are also described in detail. The results of wear testing five types of knee prostheses were that the wear rate was nearly an inverse relationship with contact area— knees with a higher contact area had lower wear rates.

Interlaboratory Groove Depth Measurements and Wear Estimation

1976 ◽  
Vol 4 (2) ◽  
pp. 59-65
Author(s):  
A. Kondo ◽  
F. C. Brenner
Keyword(s):  
Wear Rate ◽  
Groove Depth ◽  
Wear Rates ◽  
Before And After ◽  
Single Operator ◽  
The Difference

Abstract A tire was measured to determine its average groove depth by each of several operators in each of seven laboratories in the morning and afternoon for two consecutive days. The results show that the operators repeat their measurements within acceptable variation. On averages of six measurements by a single operator, a difference of 0.002 in. (0.05 mm) was significant. The variability of operators' averages around their laboratory average was the same for all laboratories except one. However, averages among laboratories were different, which is attributed to small differences in the measuring practice. The precision of wear rate estimates based on the difference of average groove depths before and after a period of wear is estimated and ways in which the precision of estimates of wear rates can be optimized are suggested.

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