scholarly journals Computer measurement of the friction of thin metal structure created in PVD technology on the flexible substrate

2019 ◽  
Vol 252 ◽  
pp. 09005
Author(s):  
Ewa Korzeniewska ◽  
Artur Szczęsny ◽  
Jerzy Józwik ◽  
Arkadiusz Tofil
Keyword(s):  
Friction Coefficient ◽  
Flexible Substrate ◽  
Metal Structure ◽  
Standard Test ◽  
Silver Layer ◽  
Test Time ◽  
Fixed Temperature ◽  
Practical Applications ◽  
Computer Measurement ◽  
Ball On Disc

The paper presents the results of research study on the phenomenon of friction of thin film electroconductive structure created on composite flexible substrate and results of measurement of the friction coefficient. Tribological tests were performed on T-01M tribotester. The measurement tests were conducted according to ASTM G133 standard with a minimum force of 1N. A ball-on-disc friction combination was used. The study was conducted at a fixed temperature of 28 ° C. Due to the nature of the tested samples, non-standard test parameters were used: test time 100 s, data acquisition frequency 10 Hz, slip velocity of the friction node 0.3 m/s on a radius of 11 mm. Based on the obtained results, the friction coefficient of the thin metallic layer Ag and Cu was determined. The obtained mean friction coefficient for a silver layer was 0.59, while for a thin copper layer 0.67. The knowledge of the determined coefficients will allow for effective and optimal use of the textronics materials tested in practical applications. The research methodology does not support determining the usage of the ball-on-disc pair.

scholarly journals A thermal resistances-based approach for thermal-elastohydrodynamic calculations in point contacts

2017 ◽  
Vol 232 (11) ◽  
pp. 2088-2102 ◽  
Author(s):  
Eduardo de la Guerra Ochoa ◽  
Javier Echávarri Otero ◽  
Enrique Chacón Tanarro ◽  
Benito del Río López
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thermal Effects ◽  
Good Accuracy ◽  
Computational Cost ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
New Approach ◽  
Ball On Disc

This article presents a thermal resistances-based approach for solving the thermal-elastohydrodynamic lubrication problem in point contact, taking the lubricant rheology into account. The friction coefficient in the contact is estimated, along with the distribution of both film thickness and temperature. A commercial tribometer is used in order to measure the friction coefficient at a ball-on-disc point contact lubricated with a polyalphaolefin base. These data and other experimental results available in the bibliography are compared to those obtained by using the proposed methodology, and thermal effects are analysed. The new approach shows good accuracy for predicting the friction coefficient and requires less computational cost than full thermal-elastohydrodynamic simulations.

Effects of out-of-contact lubricant channeling on friction and film thickness in starved elastohydrodynamic lubrication point contacts

2016 ◽  
Vol 231 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Fadi Ali ◽  
Ivan Křupka ◽  
Martin Hartl
Keyword(s):  
Film Thickness ◽  
Digital Camera ◽  
Elastohydrodynamic Lubrication ◽  
Contact Condition ◽  
Friction Reduction ◽  
Rolling Element Bearings ◽  
Point Contacts ◽  
Practical Applications ◽  
Rolling Element ◽  
Ball On Disc

This study presents experimental results on the effect of out-of-contact lubricant channeling on the tribological performance of nonconformal contacts under starved lubrication. Channeling of lubricant was carried out by adding a slider with a limited slot for scraping the displaced lubricant on one of mating surfaces (ball). Thus, the scraped lubricant is forced to flow back into the depleted track through the limited slot resulting in robust replenishment. The measurements have been conducted using optical tribometer (ball-on-disc) equipped with a digital camera and torque sensor. The effect of lubricant channeling was compared to the original contact condition by means of measuring friction and film thickness. The results show that the out-of-contact lubricant channeling leads to a significant enhancement of film thickness and friction reduction under starved conditions. Indeed, the starved elastohydrodynamic lubrication contacts transformed to the fully flooded regime after introducing the flow reconditioning. Moreover, the film thickness decay over time, which is common with starved elastohydrodynamic lubrication contacts, has not been observed in the case of lubricant channeling. However, the beneficial effect of lubricant channeling diminishes as the original contact condition tends to the fully flooded regime. The results of this study can be easily implemented in practical applications such as radial and thrust rolling-element bearings.

Behavior evaluation and effects of different lubricants in ECAP process

2017 ◽  
Vol 69 (5) ◽  
pp. 701-707
Author(s):  
Seyed Husein Hasani Najafabadi ◽  
Ali Akbar Lotfi Neyestanak ◽  
Saeed Daneshmand
Keyword(s):  
Friction Coefficient ◽  
Process Parameters ◽  
Effective Strain ◽  
Mesh Size ◽  
Industrial Applications ◽  
Zinc Stearate ◽  
Content Type ◽  
Practical Applications ◽  
Angular Pressing ◽  
Ecap Process

Purpose The purpose of equal channel angular pressing (ECAP) is producing ultra-fine grain materials. In practical applications, it is important to understand and predict effect of different process parameters on deformed parts. One of the most important process parameters is friction coefficient. Behavior evaluation of different lubricants in the ECAP process is the aim of this research. Design/methodology/approach The present study concerns the experimental measurements of the effective strain by means of gridded parts for three different lubricants, graphite, molybdenum disulfide and zinc stearate, to evaluate friction coefficient in ECAP process. Mesh size was 2 × 2 mm2 and embedded in parts made of AL2024; process was done in ambient temperature, and parts were in annealed situation. After the process, strain measured by optical and analytical methods for evaluation of lubricants’ behavior with different friction coefficients. Findings This study shows that zinc stearate has better effects rather than other lubricants in ECAP process and ECAPed parts. Originality/value The fatal challenge for researchers and industrial applications of ECAP process is lubrication. This research is a guide for scientists and engineers (in the future applications) to reduce and control bad frictional effects, produce better parts (more strain homogenous parts), prevent die failures and decrease press tonnage in ECAP process.

Effect of Atmosphere Temperature on Physical Properties of ZnO/Ag/ZnO on PET Films

2014 ◽  
Vol 988 ◽  
pp. 125-129 ◽  
Author(s):  
Yun Hae Kim ◽  
Jin Woo Lee ◽  
Riichi Murakami ◽  
Dong Myung Lee ◽  
Jin Cheol Ha ◽  
...  
Keyword(s):  
Band Gap ◽  
Sheet Resistance ◽  
Chemical Properties ◽  
Raw Material ◽  
Silver Layer ◽  
Visible Range ◽  
Potential Candidate ◽  
Practical Applications ◽  
Ito Film ◽  
Transparent Conducting

Transparent conductive layers on flexible substrates are important components of today’s optoelectronic technology. They are used in filters for plasma displays, low-e windows, solar cells, etc. At present, in-doped indium oxide (ITO) layers on PET substrate is the predominant transparent conducting oxide film in diverse practical applications. However, ITO is a relatively expensive material because indium is not abundant, but aluminum-doped zinc oxide (AZO) film is emerging as an alternative potential candidate to ITO thin film due to its abundance as a raw material, nontoxic nature, cost-effectiveness, easy fabrication, and good stability in plasma. They have, however, several drawbacks: they exhibit relatively high electrical resistance (sheet resistance, 20-200Ω), considerable emissivity, and significant absorption in the spectral region 1-2μm, in which transition from high transmittance to high reflectance takes place. Furthermore, these films do not block solar thermal radiation (0.7-3μm), which may cause overheating problems to devices such as electro-chromic and photovoltaic devices. On the other hand, ITO/Ag/ITO multilayer films are used to achieve high transparent conducting properties. A thin silver layer of about 10nm thickness is embedded between two ITO layers. The ITO/Ag/ITO film has very low sheet resistance, high optical transparency in the visible range, relatively lower thickness than single-layered ITO film, and better durability than single-layered silver film. In terms of ZnO, which is a wide direct band-gap semiconductor, ZnO has a band-gap energy of 3.37 eV with a binding energy as high as 60 meV at room temperature. ZnO has been applied to various domains for excellent physical and chemical properties, such as piezoelectric sensors, rheostats , gas sensors, semiconductor lasers, and transparent conductive films.

Research on the Tribological Property of Synthetic Multilayer MoS2/FeS Film under Dry Condition

2011 ◽  
Vol 217-218 ◽  
pp. 1117-1122 ◽  
Author(s):  
Jia Jie Kang ◽  
Cheng Biao Wang ◽  
Hai Dou Wang ◽  
Bin Shi Xu ◽  
Jia Jun Liu ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Low Temperature ◽  
Magnetron Sputtering ◽  
Tribological Property ◽  
Smooth Surface ◽  
Multilayer Film ◽  
Spherical Particles ◽  
Novel Method ◽  
1045 Steel ◽  
Ball On Disc

In this paper, we adopted a novel method, namely, magnetron sputtering + low temperature ion sulfurizing composite technology to prepare synthetic MoS2/FeS multilayer film. The obtained film has a quite smooth surface with plenty of spherical particles. The friction tests were carried out on a ball-on-disc tester under dry condition. During the whole test, the friction coefficient of the MoS2/FeS multilayer film was always lower than that of the original 1045 steel and FeS film. In addition, the wear scar depth of the MoS2/FeS multilayer film was also low. It is undoubtedly that the synthetic MoS2/FeS multilayer film possesses excellent friction-reducing and wear-resisting behaviors.

scholarly journals Secure machine learning against adversarial samples at test time

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Jing Lin ◽  
Laurent L. Njilla ◽  
Kaiqi Xiong
Keyword(s):  
Machine Learning ◽  
Parallel Implementation ◽  
Standard Test ◽  
Test Time ◽  
Test Accuracy ◽  
Learning Approaches ◽  
Complex Models ◽  
Projected Gradient Descent ◽  
Adversarial Example ◽  
Human Eyes

AbstractDeep neural networks (DNNs) are widely used to handle many difficult tasks, such as image classification and malware detection, and achieve outstanding performance. However, recent studies on adversarial examples, which have maliciously undetectable perturbations added to their original samples that are indistinguishable by human eyes but mislead the machine learning approaches, show that machine learning models are vulnerable to security attacks. Though various adversarial retraining techniques have been developed in the past few years, none of them is scalable. In this paper, we propose a new iterative adversarial retraining approach to robustify the model and to reduce the effectiveness of adversarial inputs on DNN models. The proposed method retrains the model with both Gaussian noise augmentation and adversarial generation techniques for better generalization. Furthermore, the ensemble model is utilized during the testing phase in order to increase the robust test accuracy. The results from our extensive experiments demonstrate that the proposed approach increases the robustness of the DNN model against various adversarial attacks, specifically, fast gradient sign attack, Carlini and Wagner (C&W) attack, Projected Gradient Descent (PGD) attack, and DeepFool attack. To be precise, the robust classifier obtained by our proposed approach can maintain a performance accuracy of 99% on average on the standard test set. Moreover, we empirically evaluate the runtime of two of the most effective adversarial attacks, i.e., C&W attack and BIM attack, to find that the C&W attack can utilize GPU for faster adversarial example generation than the BIM attack can. For this reason, we further develop a parallel implementation of the proposed approach. This parallel implementation makes the proposed approach scalable for large datasets and complex models.

Evaluation of the tribological performance of the green hBN nanofluid on the friction characteristics of AISI 316L stainless steel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sıtkı Akincioğlu ◽  
Şenol Şirin
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
316L Stainless Steel ◽  
Tribological Performance ◽  
Performance Criteria ◽  
Aisi 316L ◽  
Aisi 316L Stainless Steel ◽  
Content Type ◽  
Test Conditions ◽  
Ball On Disc

Purpose The purpose of this study is to investigate the effect of new green hexagonal boron nitride (hBN) nanofluid on AISI 316L stainless friction coefficient, wear resistance and wear using a ball on disc tester. Design/methodology/approach Nanofluids were prepared by adding hBN nanoparticles with two-step method to the vegetable-based oil at 0.50 vol%. Before the experiments, hBN nanofluid viscosity, pH and thermal conductivity specifications were determined. Friction tests of AISI 316L stainless steel were performed under 2 N, 5 N and 8 N loads at 400 rpm using a ball-on-disc test device under dry, oil and hBN conditions. Coefficient of friction, wear profile, surface integrity and wear mechanisms were chosen as performance criteria. Findings The friction coefficient values obtained under the oil and hBN test conditions with the 8 N load were, respectively, 72.46% and 77.64% lower than those obtained under dry test conditions. hBN nanofluid performed better on surface topography, and especially wear, compared to the dry and oil test conditions. Practical implications The aim of this study was to determine the best tribological performance of the hBN nanofluid on AISI 316L stainless steel used in orthopedic applications. Originality/value The paper is a study investigating the effect of hBN nanoparticle additive in vegetable-based oil on friction and wear performance of AISI 316L stainless steel. It is an original paper and is not published elsewhere.

Wear Response of Composition-Modulated Multilayer Ni-W Coatings

2014 ◽  
Vol 1025-1026 ◽  
pp. 302-309 ◽  
Author(s):  
Nattadon Udompanit ◽  
Panyawat Wangyao ◽  
Suparoek Henpraserttae ◽  
Yuttanant Boonyongmaneerat
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Chemical Composition ◽  
Friction Coefficient ◽  
Microstructural Analysis ◽  
Individual Layer ◽  
Increase Wear Resistance ◽  
Wear Response ◽  
The Individual ◽  
Ball On Disc

The present studies investigate the wear response of composition-modulated multilayer Ni-W coatings as fabricated by electrodeposition. By regulating the pulse waveforms of the applied currents, the chemical composition, grain size, and the individual layer thickness of the electrodeposited Ni-W CMMC can be tailored. The ball-on-disc test and the subsequent microstructural analysis indicates that the wear resistance and friction coefficient of Ni-W CMMC are influenced by the composition and the thickness of the individual alternating layer. The decrement of interlayer’s size monotoically increase wear resistance and friction coefficient.

scholarly journals A Designed Broadband Absorber Based on ENZ Mode Incorporating Plasmonic Metasurfaces

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 673 ◽  
Author(s):  
Dang ◽  
Le ◽  
Lee ◽  
Nguyen
Keyword(s):  
Numerical Study ◽  
Metal Structure ◽  
Infrared Region ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Light Illumination ◽  
Broadband Absorber ◽  
Practical Applications ◽  
Solar Energy Harvesting ◽  
Wide Range

In this paper, we present a numerical study of a metamaterial absorber that provides polarization-insensitive absorption over a broad bandwidth of operation over the mid-infrared region. The absorber consists of a periodically patterned metal-dielectric-metal structure integrated with an epsilon-near-zero (ENZ) nanolayer into the insulating dielectric gap region. Such an anomalous broadband absorber is achieved thanks to a couple of resonant modes including plasmon and ENZ modes that are excited under mid-IR light illumination. By adding a 0.06-μm-thick ENZ layer between the patterned gold rectangular grating and the SiO2 dielectric layer, the absorber captures >95% light over a 1.5 µm bandwidth centered at a near-8-μm wavelength over a wide range of oblique incidence under transverse-magnetic and -electric polarizations. The designed ENZ-based wideband absorber has potential for many practical applications, including sensing, imaging and solar energy harvesting over a wide frequency regime.

TRIBOLOGICAL PROPERTIES OF AG/BSCCO SELF-LUBRICATING COMPOSITES

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2664-2669
Author(s):  
LIRONG DONG ◽  
CHANGSHENG LI ◽  
TANG HUA
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Tribological Properties ◽  
Test Time ◽  
Powder Metallurgy Method ◽  
Superconducting Transition ◽  
Test Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electronic Microscope

The superconductors Bi 2 Sr 2 CaCu 2 O x ( Bi 2212 ) and Ag / Bi 2212 composites samples were prepared by the powder metallurgy method. The frictional behaviors of Bi 2212 pins in contact with stainless steel plate were examined from -196 to 20°C on friction and wear tester. When the temperature was lower than the superconducting transition temperature, the friction coefficient of Bi 2212 dropped sharply, and it kept 0.11 with increase of the test time. The microstructure and morphology of Ag / Bi 2212 composites were investigated by means of X-ray diffraction (XRD), transmission electronic microscope (TEM) and high resolution transmission electronic microscope (HRTEM). The elemental compositions of the worn surfaces of Ag / Bi 2212 composites were determined by using energy dispersive X-ray analysis (EDXA). The results showed that the superconducting structure of Bi 2212 was not changed and Ag was distributed in the Bi 2212 matrix. Ag doping improved the toughness of oxide ceramics Bi 2212. The friction test results of Ag / Bi 2212 composites showed the tribological properties were improved at room temperature. The friction coefficient of 10% Ag / Bi 2212 against stainless steel showed a lower value (0.2) and the wear rate of 15% Ag / Bi 2212 was minimum (9.5×10-5 mm3·(N·m)-1 ). The lubrication of soft metallic film and load of hard matrix were the mechanism of decreased friction and anti-wear of Ag / Bi 2212 composites.

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