scholarly journals Tribology of High-performance PEEK-, PI-, and ATSP-based Self-lubricating Polymers Up to 300 oC

2021 ◽  
Author(s):  
Kian Bashandeh ◽  
Pixiang Lan ◽  
Andreas A. Polycarpou
Keyword(s):  
High Performance ◽  
Tribological Performance ◽  
Low Friction ◽  
Transfer Films ◽  
Overall Performance ◽  
Low Wear ◽  
Pin On Disk ◽  
Environmental Temperatures ◽  
Lubricating Properties

Abstract High-performance polymers (HPPs) with self-lubricating properties are promising materials for bearing and tribological components that demand low friction and low wear in the absence of liquid lubrication. This study reports on the tribological performance of three advanced HPPs, namely ATSP-, PEEK-, and PI-based polymer composites. The experiments were performed using pin-on-disk configuration under dry sliding conditions and different environmental temperatures from 25 (room temperature) to 300 °C. The role of temperature on the formation of polymer transfer films on the steel counterpart was investigated using microscopy and profilometric measurements, and correlations were made to their tribological performance. From the three tested composites, ATSP-based composite exhibited the best overall performance with low friction and low wear.

scholarly journals Effect of Bias Voltage on Microstructure and Properties of Tantalum Nitride Coatings Deposited by RF Magnetron Sputtering

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 911
Author(s):  
Wei Dai ◽  
Yunzhan Shi
Keyword(s):  
Magnetron Sputtering ◽  
Bias Voltage ◽  
Rf Magnetron Sputtering ◽  
Amorphous Structure ◽  
Tribological Performance ◽  
Tantalum Nitride ◽  
Growth Morphology ◽  
Low Friction ◽  
Nitride Coatings ◽  
Overall Performance

TaNx coatings were deposited by RF magnetron sputtering with different bias voltages. The growth morphology, crystalline structure, chemical bond structure, hardness and elastic modulus, adhesion strength and tribological performance of the coatings were studied as a function of the bias voltage. The results showed that an increasing bias voltage refines the coating grains and facilitates structure densification. Simultaneously, the structure of the TaNx coatings transfers from a composite structure consisting of TaN and Ta2N crystals, through a single composite mainly composed of the Ta2N crystal, to an amorphous structure as the bias voltage increases from low to high, indicating that the phase composition of the TaNx coatings can be varied by the bias voltage. The coating composed of Ta2N crystal showed a good overall performance including enhanced hardness, enhanced adhesive strength, and good tribological performance with enhanced wear resistance and a low friction coefficient of 0.18.

A Tribological Study of Mo/Al2O3 in Sliding Contact

1988 ◽  
Vol 140 ◽  
Author(s):  
Hyun-Soo Hong ◽  
Ward O. Winer
Keyword(s):  
Wear Rate ◽  
Molybdenum Oxide ◽  
Sliding Contact ◽  
Tribological Study ◽  
Real Area Of Contact ◽  
Low Wear ◽  
Real Area ◽  
Lubricating Properties

AbstractThis is Part II of a tribological study of metal/ceramic pair in a sliding contact. The tribological behavior of molybdenum against a single crystal A12O3 was investigated at bulk temperatures of 23ºC and 400ºC using a sliding speed of 4 m/s and loads from nine to twenty five Newtons. The role of oxidational wear was confirmed at both temperatures. The linear dependency of wear rate on load was identified at 23ºC tests. At 400ºC, there was a rapid increase of wear rate at a load of about 25 N possibly due to the volatilization of MoO3, which is the limitation of molybdenum oxide as a solid lubricant. However, this study showed that the out-of-contact oxide formation may have prevented the catastrophic oxidation during contact at the real area of contact. It also showed that in-situ formed molybdenum oxide has good lubricating properties (≃ 0.3) and a low wear rate (≃ 10-14 m3/m). Therefore, this molybdenum can be used for a large range of sliding speeds and loads.

scholarly journals A Review on the Role of the Neuroscience of Flow States in the Modern World

2020 ◽  
Vol 10 (9) ◽  
pp. 137
Author(s):  
Joshua Gold ◽  
Joseph Ciorciari
Keyword(s):  
Skill Acquisition ◽  
High Performance ◽  
Peak Performance ◽  
Modern World ◽  
General Technique ◽  
Current State ◽  
Novel Method ◽  
Overall Performance ◽  
Flow States

Flow states have been shown to help people reach peak performance, yet this elusive state is not easily attained. The review describes the current state of literature on flow by addressing the environmental influences as well as the cognitive and neurocognitive elements that underlie the experience. In particular, the research focusses on the transition of cognitive control from an explicit to an implicit process. This is further expanded upon to look at the current, yet related neurocognitive research of high performance associated with the implicit process of automaticity. Finally, the review focusses on transcranial direct current stimulation (tDCS) as a novel method to facilitates an induction of flow states. Implications are aimed at a general technique to improve on skill acquisition and overall performance.

The Tribological Behavior of MoS2-Cr Films Sliding Against an Aluminum Counterface

2004 ◽  
Vol 843 ◽  
Author(s):  
James E. Krzanowski
Keyword(s):  
Wear Track ◽  
Tribological Performance ◽  
Transfer Film ◽  
Interface Reactions ◽  
Transfer Films ◽  
The Coefficient Of Friction ◽  
Oxide Particles ◽  
Pin On Disk ◽  
Cr Film ◽  
Al Oxide

ABSTRACTThe tribological performance of MoS2-Cr films in a pin-on-disk test sliding against an aluminum ball has been examined in this study. The MoS2-Cr films were deposited by pulsed laser deposition (MoS2) and simultaneous sputter deposition of Cr, giving a Cr content in the film of 10 mol. %. The results were also compared with films of MoS2 alone. The frictional behavior of MoS2-Cr films was not improved compared to the MoS2 alone, so SEM/EDS studies of the ball and flat were conducted to determine the nature of the transfer films and examine any interface reactions that occurred during the pin-on-disk (POD) test. In the early stages of the POD test (500 cycles) on the MoS2-Cr film, Al-oxide particles formed and caused cratering and scratching of the wear track, and the coefficient of friction neared 0.7. At later stages (9000 cycles), a thick oxide-based transfer film formed on the ball, but on the flat the track composition was closer to that of the original coating. For the films without Cr, after 104 cycles a smooth wear track was observed, and a thin transfer film of MoS2 was found within grooves on the ball wear scar along with Al oxide, which resulted in superior tribological performance.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

Two Short Tests Fail to Detect Vigilance Decrements

2001 ◽  
Vol 17 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Juan Botella ◽  
María José Contreras ◽  
Pei-Chun Shih ◽  
Víctor Rubio
Keyword(s):  
Individual Differences ◽  
High Performance ◽  
Selection Process ◽  
Vigilance Task ◽  
Air Traffic Controllers ◽  
Job Selection ◽  
Performance Deterioration ◽  
Short Test ◽  
Psychological Dimensions

Summary: Deterioration in performance associated with decreased ability to sustain attention may be found in long and tedious task sessions. The necessity for assessing a number of psychological dimensions in a single session often demands “short” tests capable of assessing individual differences in abilities such as vigilance and maintenance of high performance levels. In the present paper two tasks were selected as candidates for playing this role, the Abbreviated Vigilance Task (AVT) by Temple, Warm, Dember, LaGrange and Matthews (1996) and the Continuous Attention Test (CAT) by Tiplady (1992) . However, when applied to a sample of 829 candidates in a job-selection process for air-traffic controllers, neither of them showed discriminative capacity. In a second study, an extended version of the CAT was applied to a similar sample of 667 subjects, but also proved incapable of properly detecting individual differences. In short, at least in a selection context such as that studied here, neither of the tasks appeared appropriate for playing the role of a “short” test for discriminating individual differences in performance deterioration in sustained attention.

Emotion information processing as a new component of emotional intelligence: Theoretical framework and empirical evidence

2021 ◽  
pp. 089020702110076
Author(s):  
Marina Fiori ◽  
Shagini Udayar ◽  
Ashley Vesely Maillefer
Keyword(s):  
Emotional Intelligence ◽  
Information Processing ◽  
Incremental Validity ◽  
Stressful Situation ◽  
Factorial Structure ◽  
Ability Emotional Intelligence ◽  
Processing Component ◽  
Overall Performance ◽  
The Relationship

The relationship between emotional intelligence (EI) and emotion information processing (EIP) has received surprisingly little attention in the literature. The present research addresses these gaps in the literature by introducing a conceptualization of emotional intelligence as composed of two distinct components: (1) EIK or emotion Knowledge component, captured by current ability emotional intelligence tests, related to top-down, higher order reasoning about emotions, and which depends more strongly on acquired and culture-bound knowledge about emotions; (2) EIP or emotion information Processing component, measured with emotion information processing tasks, requires faster processing and is based on bottom-up attention-related responses to emotion information. In Study 1 ( N = 349) we tested the factorial structure of this new EIP component within the nomological network of intelligence and current ability emotional intelligence. In Study 2 ( N =111) we tested the incremental validity of EIP in predicting both overall performance and the charisma of a presenter while presenting in a stressful situation. Results support the importance of acknowledging the role of emotion information processing in the emotional intelligence literature and point to the utility of introducing a new EI measure that would capture stable individual differences in how individuals process emotion information.

scholarly journals Functional response of Harmonia axyridis preying on Acyrthosiphon pisum nymphs: the effect of temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yasir Islam ◽  
Farhan Mahmood Shah ◽  
Xu Rubing ◽  
Muhammad Razaq ◽  
Miao Yabo ◽  
...  
Keyword(s):  
Functional Response ◽  
High Performance ◽  
Acyrthosiphon Pisum ◽  
Harmonia Axyridis ◽  
Effect Of Temperature ◽  
Functional Responses ◽  
Aphid Control ◽  
Host Aphid ◽  
Predator Foraging

AbstractIn the current study, we investigated the functional response of Harmonia axyridis adults and larvae foraging on Acyrthosiphon pisum nymphs at temperatures between 15 and 35 °C. Logistic regression and Roger’s random predator models were employed to determine the type and parameters of the functional response. Harmonia axyridis larvae and adults exhibited Type II functional responses to A. pisum, and warming increased both the predation activity and host aphid control mortality. Female and 4th instar H. axyridis consumed the most aphids. For fourth instar larvae and female H. axyridis adults, the successful attack rates were 0.23 ± 0.014 h−1 and 0.25 ± 0.015 h−1; the handling times were 0.13 ± 0.005 h and 0.16 ± 0.004 h; and the estimated maximum predation rates were 181.28 ± 14.54 and 153.85 ± 4.06, respectively. These findings accentuate the high performance of 4th instar and female H. axyridis and the role of temperature in their efficiency. Further, we discussed such temperature-driven shifts in predation and prey mortality concerning prey-predator foraging interactions towards biological control.

scholarly journals Effect of Different Lubricating Environment on the Tribological Performance of CNT Filled Glass Reinforced Polymer Composite

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2965
Author(s):  
Sandeep Agrawal ◽  
Nishant K. Singh ◽  
Rajeev Kumar Upadhyay ◽  
Gurminder Singh ◽  
Yashvir Singh ◽  
...  
Keyword(s):  
Tribological Performance ◽  
Hardened Steel ◽  
Dry Sliding ◽  
Gfrp Composites ◽  
Tribological Behaviour ◽  
Reinforced Polymer ◽  
Steel Surfaces ◽  
Lubrication Properties ◽  
Scanning Electron

In recent years, the engineering implications of carbon nanotubes (CNTs) have progressed enormously due to their versatile characteristics. In particular, the role of CNTs in improving the tribological performances of various engineering materials is well documented in the literature. In this work, an investigation has been conducted to study the tribological behaviour of CNTs filled with glass-reinforced polymer (GFRP) composites in dry sliding, oil-lubricated, and gaseous (argon) environments in comparison to unfilled GFRP composites. The tribological study has been conducted on hardened steel surfaces at different loading conditions. Further, the worn surfaces have been examined for a particular rate of wear. Field-emission scanning electron (FESEM) microscopy was used to observe wear behaviours. The results of this study explicitly demonstrate that adding CNTs to GFRP composites increases wear resistance while lowering friction coefficient in all sliding environments. This has also been due to the beneficial strengthening and self-lubrication properties caused by CNTs on GFRP composites, according to FESEM research.

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