scholarly journals Excellent Seizure and Friction Properties Achieved with a Combination of an a-C:H:Si DLC-Coated Journal and an Aluminum Alloy Plain Bearing

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1055
Author(s):  
Takumi Iwata ◽  
Masakuni Oikawa ◽  
Riki Chida ◽  
Daijiro Ishii ◽  
Hidemi Ogihara ◽  
...  
Keyword(s):  
Marked Improvement ◽  
International Organization ◽  
Friction Reduction ◽  
Test Results ◽  
Specific Load ◽  
Large Share ◽  
Bearing Material ◽  
Automotive Engines ◽  
Dlc Coating ◽  
Hydrogenated Amorphous

Friction occurring between the crank journal and main bearings accounts for a large share of the mechanical losses of automotive engines. The effects of higher in-cylinder pressures and narrower bearings have raised the specific load applied to bearings, making it essential to secure sufficient seizure resistance as well. For the purpose of meeting both requirements, we have endeavored to reduce friction and improve seizure resistance by applying a diamond-like carbon (DLC) coating to the crank journal. In the present study, a bearing tester was used that has received international standard certification from the International Organization for Standardization for reproducing the sliding behavior occurring between the crank journal and main bearings in actual engines. Test results indicated that a silicon-containing hydrogenated amorphous carbon (a-C:H:Si) DLC-coated journal showed a definite friction reduction and a marked improvement in seizure resistance. An acoustic emission (AE) analysis revealed that an adhesion-induced AE peak observed for a steel journal was not seen for the DLC-coated journal. Additionally, tin and aluminum elements in the bearing material that were transferred to and observed on the sliding surface of the steel journal were not seen on the DLC-coated journal. Accordingly, the low affinity of the DLC coating with these metal elements presumably led to the clear friction reduction and superior seizure resistance displayed by the DLC coating.

Low Friction Realised by Hydrogen-Ended DLC Surface Through Photocatalyst Effect in Water Lubricated Condition

2020 ◽  
Author(s):  
Motoyuki Murashima ◽  
Yusuke Imaizumi ◽  
Takazumi Yamada ◽  
Katsuno Shotaro ◽  
Tomoki Yoshida ◽  
...  
Keyword(s):  
Reduction Method ◽  
Water Electrolysis ◽  
Repulsive Force ◽  
Friction Reduction ◽  
Friction Test ◽  
Low Friction ◽  
Dlc Coatings ◽  
Dlc Coating ◽  
Hydrogenated Amorphous ◽  
Test Result

Abstract This study shows a new friction reduction method for a diamond-like carbon (DLC) coating using photocatalyst in water lubricated condition. It is well known that one of DLC coatings (e.g. hydrogenated amorphous carbon, a-C:H) exhibits low friction due to repulsive force generated by hydrogens on their top most surfaces. Thus, the low friction is mainly occurred in inert gas environment. On the other hand, if we can produce hydrogenated surface positively, low friction may be achieved in lubricated conditions. Here, it is well known that water electrolysis by photocatalyst generates hydrogen and oxygen atoms/molecules. In this research, we propose a new hydrogen terminating method for DLC surfaces with hydrogens generated by water electrolysis. Moreover, we clarified the effect of the hydrogen-end on lowering friction. We conducted friction tests using an a-C:H coating against a TiO2 disk (photocatalyst) in water lubricated condition. The friction test result showed a decrease in the friction coefficient which was associated with UV irradiation. It is considered that the reduction in hydrogen-bonding component of surface energy indicates a highly hydrogen-ended surface creation, resulting in higher repulsive force and lower friction.

Design and Testing of ITER TF Coil Insulations

2011 ◽  
Vol 21 (3) ◽  
pp. 3127-3131 ◽  
Author(s):  
Matthew W. Hooker ◽  
Jennifer K. Walsh ◽  
Mark W. Haynes ◽  
Naseem A. Munshi
Keyword(s):  
Radiation Exposure ◽  
Large Scale ◽  
Mechanical Performance ◽  
International Organization ◽  
Vacuum Impregnation ◽  
Test Results ◽  
Qualification Test ◽  
Insulation System ◽  
Cyanate Ester Resin ◽  
Design And Testing

The design of the ITER Toroidal Field (TF) coils requires an insulation system that is amenable to the very large scale vacuum impregnation processes planned for the construction of these devices, and that will provide reliable electro-mechanical performance after radiation exposure. To address this need, CTD has developed an epoxy/cyanate ester resin system designated CTD-425. This material meets the processing requirements for use in the TF coils, and cyclic mechanical testing of conductor assemblies has demonstrated its electro-mechanical strength after 60,000 mechanical cycles. In addition, this product recently passed radiation exposure tests coordinated by the ITER International Organization and is now qualified for use in constructing the TF coils. This paper summarizes the performance characterization and qualification test results for this insulation.

Fabrication of Bionic Silicon Surfaces with Lotus Effect and their Micro Tribological Performance

2010 ◽  
Vol 97-101 ◽  
pp. 1393-1398 ◽  
Author(s):  
Xi Qiu Fan
Keyword(s):  
Surface Effect ◽  
Tribological Performance ◽  
Friction Reduction ◽  
Silicon Surfaces ◽  
Test Results ◽  
Feature Size ◽  
Lotus Effect ◽  
Lotus Leaf ◽  
Novel Approach ◽  
Leaf Surfaces

With the miniature of micro-electromechanical systems (MEMS), surface effect is substantially increased, and the resulting friction, abrasion and stiction are becoming bottlenecks of the development of MEMS industry. In this paper, firstly, the feature size and topography on lotus leaf surfaces is investigated, as well as the mechanism of lotus effect applied in MEMS to reduce friction and prevent stiction is analyzed; secondly, two approaches of fabricating bionic silicon surfaces with lotus effect are proposed; finally, test results on the micro tribological performance of the mimicked silicon surfaces are presented, which demonstrates that to mimic lotus effect on silicon surfaces is a novel approach to prevent stiction and reduce friction . However, the effectiveness of stiction prevention and friction reduction is related to the size and shape of the textured structures.

Hydrodynamic Aspects of Fatigue in Plain Journal Bearings

1981 ◽  
Vol 103 (1) ◽  
pp. 150-156 ◽  
Author(s):  
F. A. Martin ◽  
D. R. Garner ◽  
D. R. Adams
Keyword(s):  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Pressure Variation ◽  
Hydrodynamic Characteristics ◽  
Specific Load ◽  
Bearing Material ◽  
Significant Term ◽  
Bearing Materials ◽  
Negative Pressures ◽  
The University

The fatigue resistance of different bearing materials is usually given an “order of merit” in terms of specific load on the bearing. The bearing material cannot directly sense the applied specific load, since it is the hydrodynamic oil film pressures which directly create the stresses in the lining; both pressures and stresses need to be examined to see if a more meaningful criterion for fatigue can be found. As a first step in this study the experimental fatigue work carried out by Gyde at the University of Denmark was examined and compared with trends in peak specific load, hydrodynamic characteristics, and bearing lining stresses. It has been shown that peak specific load and peak hydrodynamic pressure are not in themselves realistic parameters, but that pressure variation on a bearing element, perhaps including some rapidly forming negative pressures, could be a significant term. The study of the more fundamental material stresses has not yet been extended to allow for the influence of any nonpositive film pressures, but results so far follow similar trends to those obtained on the pressure variation criterion.

scholarly journals Within-site variability and reliability of foundation designs based on load tests

2019 ◽  
Author(s):  
◽  
Andrew Z. Boeckmann
Keyword(s):  
Load Test ◽  
Test Results ◽  
Considerable Variability ◽  
Specific Load ◽  
Primary Input ◽  
Bayesian Techniques ◽  
Test Information ◽  
Load Tests ◽  
A Site ◽  
Site Variability

Probabilistic evaluations of the reliability of foundation designs based on site-specific load test information are somewhat limited in number. Published evaluations have generally relied on Bayesian techniques. A primary input for Bayesian analysis is within-site variability, which describes the variability of foundation resistance across a site. Within-site variability is attributed to geologic variation across a site and to differences in construction outcomes among foundation elements. Published evaluations have generally used a deterministic value of within-site variability wherein within-site variability is treated as a known parameter and is not subject to updating based on load test results. In contrast, probabilistic within-site variability treats within-site variability as an uncertain parameter with its own probability distribution that is updated based on load test results. Probabilistic within-site variability has not been applied commonly. This research examines differences in reliability outcomes between deterministic and probabilistic within-site variability. Analysis of micropile load test results from five different sites was used to develop a distribution of within-site variability. The resulting distribution is relatively variable (i.e. the value of within-site variability is, itself, variable), which demonstrates that there is, in fact, considerable variability and uncertainty in the value of within-site variability.

Study on fatigue strength of SnSb11Cu6 babbitt-steel bimetal sliding bearing material prepared by MIG brazing

2020 ◽  
Vol 21 (1) ◽  
pp. 106
Author(s):  
Xinbo Wang ◽  
Zhongwei Yin ◽  
Yonghong Chen
Keyword(s):  
Fatigue Strength ◽  
Internal Combustion Engines ◽  
Centrifugal Casting ◽  
Test Method ◽  
Engineering Practice ◽  
Test Machine ◽  
Test Results ◽  
Bearing Material ◽  
Sliding Bearing ◽  
Bearing Materials

The babbitt-steel bimetal sliding bearing material prepared by the MIG brazing has been applied in many fields. In the application, usually only the bonding force is tested, and the fatigue strength is not evaluated. For this reason, this study referred to the test method for the fatigue strength of bearing materials of internal combustion engines, used the sapphire test machine (Dana Glacier Vandervell Bearings, UK) to inspect the SnSb11Cu6 babbitt-steel bimetal material prepared by MIG brazing, and analyzed the test results in depth. The test results show that, the fatigue strength of the bimetal material is more than 40 MPa. In comparison, according to the same test method and conditions on the same sapphire test machine, the fatigue strength of the SnSb11Cu6 babbitt-steel bimetal bearing material obtained by the centrifugal casting method after optimizing process was usually around 35 MPa. Therefore, the MIG brazing could produce higher fatigue strength for SnSb11Cu6 babbitt-steel bimetal bearing material. In addition, in this study, the process of fatigue failure was usually that after the microcracks were generated on the surface, they expanded to the inside of the lining, thereby resulting in spalling. This study has guiding significance for engineering practice and scientific research.

Self-Lubricated Modification for Silicon Nitride Ceramic Ball Surface

2010 ◽  
Author(s):  
Le Gu ◽  
Guangze Tang ◽  
Chuanwei Zhang ◽  
Cuini Jing ◽  
Liqin Wang
Keyword(s):  
Silicon Nitride ◽  
Solid Lubricants ◽  
Test Results ◽  
Silicon Nitride Ceramic ◽  
Ceramic Ball ◽  
Dlc Film ◽  
Dlc Coating ◽  
Ceramic Surfaces ◽  
Mos2 Film ◽  
Ball Surface

Some thin films were prepared as solid lubricants on the surfaces of silicon nitride ceramic disk and ball. DLC film about 500–800 nm thickness was deposited on the ceramic surfaces using ion implantation and deposition technology. The surface roundness measure results, as well as 80 to 90 nm, showed that DLC film was shaped uniformly on the ceramic ball surfaces. The ball-on-disk tests showed DLC coating on silicon nitride surfaces could lead the friction coefficient to about 0.1 and endure about 7h at 1.5GPa and 30 mm/s. Ball milling technology was employed to prepare MoS2 film on the ceramic ball surfaces. The film thickness and tribological test results showed that the thin MoS2 film on the ball surfaces, which hardly changed the surface roughness, also improved their wear behaviors.

A Study of Resin Overlay Bearing Material for Recent Automotive Engines

2013 ◽  
Author(s):  
Hiroki Kobayakawa ◽  
Hideo Tsuji ◽  
Naohisa Kawakami ◽  
Colin McAleese ◽  
Hiromitsu Katsuki ◽  
...  
Keyword(s):  
Bearing Material ◽  
Automotive Engines

scholarly journals Evaluating the Mechanical and Tribological Properties of DLC Nanocoated Aluminium 5051 Using RF Sputtering

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
L. Natrayan ◽  
Anjibabu Merneedi ◽  
Dhinakaran Veeman ◽  
S. Kaliappan ◽  
P. Satyanarayana Raju ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Rf Sputtering ◽  
Wear Behaviour ◽  
Deposition Mechanism ◽  
Dlc Coatings ◽  
Sputtering Deposition ◽  
Mechanical And Tribological Properties ◽  
Automotive Engines ◽  
Dlc Coating ◽  
Insight Into

The diamond-like carbon- (DLC-) coating technique is used in the sliding parts of automotive engines, among other applications, to reduce friction and wear. In this work, DLC has been coated on the Aluminium 5051 sample to assess the mechanical and tribological properties. A sputtering deposition mechanism is used, and the DLC is coated using a graphite target. The developed DLC coatings are tested for adhesion strength, hardness, chemical composition using XRD, and wear behaviour. The developed DLC thin films have considerably increased the wear behaviour of the Aluminium 5051 sample and have fulfilled the objective of this study. The XRD data indicated the presence of amorphous carbon in the coating with a threefold increase to the hardness of the naked aluminium. This study provides insight into improving the aluminium wear resistance by developing a considerably hard coating.

scholarly journals Influence of Contamination of Gear Oils in Relation to Time of Operation on Their Lubricity

2021 ◽  
Vol 11 (24) ◽  
pp. 11835
Author(s):  
Leszek Gil ◽  
Krzysztof Przystupa ◽  
Daniel Pieniak ◽  
Edward Kozłowski ◽  
Katarzyna Antosz ◽  
...  
Keyword(s):  
Solid Particles ◽  
Friction Reduction ◽  
Test Results ◽  
Oil Viscosity ◽  
Heavy Trucks ◽  
History Of ◽  
Gear Oil ◽  
Wear Products ◽  
Gear Oils ◽  
Time Of Operation

The quality and reliability of consumables, including gear oils, results in the failure-free operation of the transmission components in heavy trucks. It is known that oil viscosity is essential for all lubricated tribopairs for wear and friction reduction in all vehicles with a gearbox. Viscosity may be influenced by the contamination that wear products can impart on the oil. Oil contamination can also affect lubrication efficiency in the boundary friction conditions in gearboxes where slips occur (including bevel and hypoid gearboxes). The present research focused on this issue. An obvious hypothesis was adopted, where it was theorized that exploiting the contaminants that are present in gear oil may affect how the lubricating properties of gear oils deteriorate. Laboratory tests were performed on contaminants that are commonly found in gear oil using the Parker Laser CM20. The study was designed to identify a number of different solid particles that are present in oil. At the second stage, friction tests were conducted for a friction couple “ball-on-disc” in an oil bath at 90 °C on a CSM microtribometer. The quantitative contamination of the gear oils that contained solid particles and the curves representing the friction coefficients of fresh oils with a history of exploitation were compared. The test results were statistically analysed. Exploitation was shown to have a significant impact on the contamination of gear oils. It was revealed that the contamination and the mileage had no effect on the tested oils.

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