scholarly journals A low-to-high friction transition in gradient nano-grained Cu and Cu-Ag alloys

Friction ◽  
2020 ◽  
Author(s):  
Xiang Chen ◽  
Zhong Han
Keyword(s):  
Subsurface Layer ◽  
Coarse Grained ◽  
Structure Evolution ◽  
Wear Loss ◽  
Strongly Correlated ◽  
Low Friction ◽  
Coarse Grained Sample ◽  
Low Wear ◽  
High Level ◽  
Worn Surface

AbstractA unique low-to-high friction transition is observed during unlubricated sliding in metals with a gradient nano-grained (GNG) surface layer. After persisting in the low-friction state (0.2–0.4) for tens of thousands of cycles, the coefficients of friction in the GNG copper (Cu) and copper-silver (Cu-5Ag) alloy start to increase, eventually reaching a high level (0.6–0.8). By monitoring the worn surface morphology evolution, wear-induced damage accumulation, and worn subsurface structure evolution during sliding, we found that the low-to-high friction transition is strongly correlated with distinct microstructural instabilities induced by vertical plastic deformation and wear-off of the stable nanograins in the subsurface layer. A very low wear loss of the GNG samples was achieved compared with the coarse-grained sample, especially during the low friction stage. Our results suggest that it is possible to postpone the initiation of low-to-high friction transitions and enhance the wear resistance in GNG metals by increasing the GNG structural stability against grain coarsening under high loading.

scholarly journals Wear and Friction Characteristics of 65Mn Steel for Spike-Tooth Harrow

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 319
Author(s):  
Zhiguo Lu ◽  
Chuanyu Du ◽  
Qingcai Chen ◽  
Tianying Niu ◽  
Na Wang ◽  
...  
Keyword(s):  
Friction And Wear ◽  
Working Environment ◽  
Manganese Steel ◽  
Wear Loss ◽  
Variable Parameters ◽  
Wear Characteristics ◽  
Before And After ◽  
Set Up ◽  
Worn Surface ◽  
Friction And Wear Characteristics

The friction and wear characteristics of spike-tooth material (65Mn steel) of Spike-Tooth Harrow in a two-stage peanut harvester were studied in this paper. The friction and wear tests of pin and disc on 65 manganese steel were carried out on the tribometer, then the wear loss and the friction coefficient were studied. The wear loss of the pin was acquired by calculating the mass of the pin before and after the experiment using an electronic balance. According to the actual working environment of peanut spring-finger, four variable parameters are set up: load, speed, soil moisture and soil type. The friction and wear characteristics of pins were studied under different loads, speeds and different soil environments. After wearing, the worn surface of the material was observed by scanning microscope and the wear mechanism was studied. The experimental results show that the wear of the pin increases with the increase of load and decreases with the increase of rotational speed in the same rotation number. Especially in the case of the sandy soil with 20% in moisture, a maximum wear loss of the pin is achieved.

Worn surface and subsurface layer structure formation behavior on wear mechanism of CoCrFeMnNi high entropy alloy in different sliding conditions

2021 ◽  
Vol 549 ◽  
pp. 149202
Author(s):  
Cheenepalli Nagarjuna ◽  
Hyeon-Jeong You ◽  
Suseong Ahn ◽  
Jun-Woo Song ◽  
Kwang-Yong Jeong ◽  
...  
Keyword(s):  
Structure Formation ◽  
Wear Mechanism ◽  
Layer Structure ◽  
Subsurface Layer ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Formation Behavior ◽  
Worn Surface

The Effect of Post-Irradiation Annealing on VVER-440 RPV Materials Mechanolocal Properties and Nano-Structure Under Re-Irradiation

2009 ◽  
Author(s):  
S. Rogozkin ◽  
A. Chernobaeva ◽  
A. Aleev ◽  
A. Nikitin ◽  
A. Zaluzhnyi ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Power Plant ◽  
Atom Probe Tomography ◽  
Nuclear Power ◽  
Temperature Shift ◽  
Atom Probe ◽  
Structure Evolution ◽  
Nano Structure ◽  
High Level ◽  
Nuclear Power Plant Unit

The present work provides the analyses of embrittlement behavior and atom probe tomography study of nano-structure evolution of VVER-440 RPV materials under irradiation and re-irradiation. Specimens from VVER-440 weld with high level of cupper (0.16 wt.%) and phosphorus (0.027–0.038 wt.%) were irradiated in surveillance channels of Rovno Nuclear Power plant unit 1 (Ro-1). The embrittlement behavior has been assessed by transition temperature shift.

scholarly journals The geochemistry of the northern part of the Ilímaussaq intrusion, S.W. Greenland

1964 ◽  
Vol 42 ◽  
pp. 1-104
Author(s):  
E.I Hamilton
Keyword(s):  
Central Area ◽  
Confining Pressure ◽  
Coarse Grained ◽  
Residual Liquid ◽  
Relative Time ◽  
Central Mass ◽  
Basement Rocks ◽  
Field Evidence ◽  
Show Evidence ◽  
High Level

The Ilímaussaq intrusion (S.W. Greenland) was emplaced into granitic Precambrian basement rocks. The intrusion is of a highly alkaline nature and in terms of rocks types, its major-, minor- and trace elements, may be compared to the Khibina-Lovozero intrusion of the Kola Peninsula, U.S.S.R. The present paper describes the geochemistry of the northern part of the intrusion and the marginal rocks. New total rock analyses are given together with the detailed geochemistry of U, Th, Radioactivity, Nb, Rb, Li and Be. The Ilímaussaq intrusion consists of an early augite syenite chilled against the country rocks. The augite syenite forms a more or less continuous ring around and above the intrusion. The main central mass of the intrusion consists of poorly layered, very coarse-grained, Na-rich "foyaite" containing relatively large amounts of sodalite and eudialyte. Differentiation of the "foyaite magma" gave rise to a volatile rich residual liquid from which lujavrites were formed. Differentiation of the lujavrites in the central area of the intrusion resulted in a lower banded sequence, the kakortokites, and an upper lujavrite liquid. When the confining pressure was exceeded, explosive brecciation occurred and lujavrite was intruded into the surrounding rocks. At a high level in the intrusion a sheet-like body of soda granite was emplaced together with various quart-bearing syenites. The relative time of intrusion of the quartz-bearing syenite is uncertain through lack of field evidence. Emplacement of the early augite syenite may be related to ring faulting followed by cauldron subsidence. The later Na-rich rocks may have replaced the earlier layered augite syenite or have been emplaced into a "magma chamber" developed by cauldron subsidence. The Na-Zr-Cl-rich rocks show evidence of cooling inwards with the development of a central volatile-rich pocket. The Ilímaussaq rocks probably represent a final highly fractionated stage of the more normal augite syenite magma common to the S. W. Greenland alkaline province.

Crankshaft Stress Analysis—Combination of Finite Element and Classical Analysis Techniques

1990 ◽  
Vol 112 (3) ◽  
pp. 268-275 ◽  
Author(s):  
A. R. Heath ◽  
P. M. McNamara
Keyword(s):  
Stress Analysis ◽  
Concept Design ◽  
Low Friction ◽  
Failure Investigation ◽  
Engine Design ◽  
Computer Based ◽  
Analysis System ◽  
High Level ◽  
Engine Components ◽  
Oil Films

The conflicting legislative and customer pressures on engine design, for example, combining low friction and a high level of refinement, require sophisticated tools if competitive designs are to be realized. This is particularly true of crankshafts, probably the most analyzed of all engine components. This paper describes the hierarchy of methods used for crankshaft stress analysis with case studies. A computer-based analysis system is described that combines FE and classical methods to allow optimized designs to be produced efficiently. At the lowest level simplified classical techniques are integrated into the CAD-based design process. These methods give the rapid feedback necessary to perform concept design iterations. Various levels of FE analysis are available to carry out more detailed analyses of the crankshaft. The FE studies may feed information to or take information from the classical methods. At the highest level a method for including the load sharing effects of the flexible crankshaft within a flexible block interconnected by nonlinear oil films is described. This method includes the FE modeling of the complete crankshaft and the consideration of its stress field throughout an engine cycle. Fatigue assessment is performed to calculate the distribution of fatigue safety factor on the surface of the crankshaft. This level of analysis can be used for failure investigation, or detailed design optimization and verification. The method is compatible with those used for vibration and oil film analysis.

RESEARCH OF THE PROPERTIES OF ZINC OXIDE NANOSTRUCTURES OBTAINED BY PULSED ELECTROCHEMICAL DEPOSITION

2019 ◽  
pp. 53-58
Author(s):  
M.N. Ilyina ◽  
A.N. Voropay ◽  
I.B. Nemchenok
Keyword(s):  
Zinc Oxide ◽  
Electrochemical Deposition ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Coarse Grained ◽  
Zinc Oxide Nanostructures ◽  
Visible Radiation ◽  
Oxide Nanostructures ◽  
Coarse Grained Sample ◽  
Kinetics Of

The properties of zinc oxide nanostructures allow it to be used in various fields of science and technology. The increased interest in this compound is caused by a rare combination of optical and electrophysical properties. The films of this compound have good piezoelectric and electroluminescent properties, due to which zinc oxide can be used as functional layers in surface acoustic waves, elements of nonlinear optics. This allows the oxide to pass visible radiation. In this paper, we study the influence of the conditions for obtaining a coating by pulsed electrochemical deposition on the forbidden zones and the power of a coating based on zinc oxide. It was shown that the temperature and duty cycle of pulses are of great importance in the formation of the coating, which is explained by the kinetics of the electrochemical reaction. The Urbach energy increases with a decrease in crystalline size and increased by almost 3 times, compared with a coarse-grained sample.

scholarly journals Evaluation of Friction Behavior and Surface Interactions of Cyano-Based Ionic Liquids under Different Sliding Contacts and High Vacuum Condition

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 69 ◽  
Author(s):  
Shouhei Kawada ◽  
Seiya Watanabe ◽  
Shinya Sasaki ◽  
Masaaki Miyatake
Keyword(s):  
Mass Spectrometry ◽  
Ionic Liquids ◽  
High Vacuum ◽  
Mass Spectrometry Analysis ◽  
Low Friction ◽  
Friction Behavior ◽  
Friction Coefficients ◽  
Spectrometry Analysis ◽  
Worn Surface ◽  
Nascent Surface

The friction coefficients of ionic liquids were evaluated by many investigations. Most investigations used fluorine-based ionic liquids as lubricants. However, these ionic liquids produce the corrosion wear. This investigation focuses on the use of cyano-based ionic liquids as lubricants. Compared to fluorine-based ionic liquids, cyano-based ionic liquids exhibit high friction coefficients against steel material. This work examines how the friction coefficients of cyano-based ionic liquids are influenced by the type of sliding material used (AISI 52100, TiO2, and tetrahedral amorphous carbon). TiO2 lubricated with 1-ethyl-3-methylimidazolium tricyanomethanide, and ta-C lubricated with 1-butyl-1methylpyrrolidinium tetracyanoborate exhibited very low friction coefficients, smaller than fluorine-based ionic liquids. Time-of-Flight Secondary Ion Mass Spectrometry analysis showed that anions adsorb onto the worn surface, suggesting that anion adsorption is a critical parameter influencing friction coefficients. Quadrupole Mass Spectrometry measurements revealed that cations decompose on the nascent surface, preventing adsorption on the worn surface. These results suggest that low friction coefficients require the decomposition of cations and adsorption of anions. The reactivity of nascent surface changes with the sliding material used due to varying catalytic activity of the nascent surfaces.

Distractor-Aware Tracking with Multi-Task and Dynamic Feature Learning

2020 ◽  
pp. 2150031
Author(s):  
Weichun Liu ◽  
Xiaoan Tang ◽  
Chenglin Zhao
Keyword(s):  
Correlation Filter ◽  
Coarse Grained ◽  
Dynamic Feature ◽  
Semantic Features ◽  
Low Level ◽  
Fine Grained ◽  
Semantic Embedding ◽  
Training Stage ◽  
Online Tracking ◽  
High Level

Recently, deep trackers based on the siamese networking are enjoying increasing popularity in the tracking community. Generally, those trackers learn a high-level semantic embedding space for feature representation but lose low-level fine-grained details. Meanwhile, the learned high-level semantic features are not updated during online tracking, which results in tracking drift in presence of target appearance variation and similar distractors. In this paper, we present a novel end-to-end trainable Convolutional Neural Network (CNN) based on the siamese network for distractor-aware tracking. It enhances target appearance representation in both the offline training stage and online tracking stage. In the offline training stage, this network learns both the low-level fine-grained details and high-level coarse-grained semantics simultaneously in a multi-task learning framework. The low-level features with better resolution are complementary to semantic features and able to distinguish the foreground target from background distractors. In the online stage, the learned low-level features are fed into a correlation filter layer and updated in an interpolated manner to encode target appearance variation adaptively. The learned high-level features are fed into a cross-correlation layer without online update. Therefore, the proposed tracker benefits from both the adaptability of the fine-grained correlation filter and the generalization capability of the semantic embedding. Extensive experiments are conducted on the public OTB100 and UAV123 benchmark datasets. Our tracker achieves state-of-the-art performance while running with a real-time frame-rate.

scholarly journals Slippery Wood: Low Friction and Low Wear of Modified Beech Wood

2020 ◽  
Vol 68 (2) ◽  
Author(s):  
O. Waßmann ◽  
S. I.-U. Ahmed
Keyword(s):  
Beech Wood ◽  
Low Friction ◽  
Low Wear
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