Evaluation of tribological characteristics of liquid lubricants with fullerene additives

The paper presents experimental studies of the tribological characteristics of liquid lubricants of various viscosity classes and various groups of operation when using fullerene additives. Tribological characteristics were evaluated on a four-ball friction machine according to GOST 9490. Assessment was subject to: wear rate and critical load, which characterize the anti-wear properties of the lubricant, as well as welding load and bully index, which characterize an anti-bully properties of the material. It is shown that the improvement of the wear index for all oils begins with the concentration 0,2 % masses, fullerenes in the lubricant and does not exceed the values 11,1 … 15 %. At a fullerene concentration less than 0,2 % masses, no positive effect is observed. Positive effect 11,8 … 17,4 % characteristic of the indicator – critical load that characterizes the range of performance of anti-wear additives. At the same time, an increase in the critical load begins with concentration 0,1 % masses, fullerenes in a lubricant and manifests itself most effectively at a concentration 0,2 % masses. Changes in the magnitude of the welding load during the experiments were not recorded, this allows us to conclude, that the addition of a finely dispersed fullerene powder in a liquid lubricant does not improve anti-bully properties, but is only an anti-wear additive. It is shown that the way to improve the tribological properties of lubricants by introducing a finely dispersed powder of fullerenes in base technical oils is ineffective. It is necessary to develop other, more technological methods and methods for introducing fullerene additives into technical lubricants.

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Evaluation of tribological characteristics of technical oils with fullerene compositions

PROBLEMS OF TRIBOLOGY ◽

10.31891/2079-1372-2020-98-4-6-12 ◽

2020 ◽

Vol 98 (4) ◽

pp. 6-12

Author(s):

A. Kravtsov ◽

Keyword(s):

Experimental Studies ◽

Fine Powder ◽

Micelle Formation ◽

Tribological Characteristics ◽

Extreme Pressure ◽

Wear Properties ◽

High Oleic ◽

Wear Indicator ◽

Positive Effect ◽

Subsequent Addition

The paper presents experimental studies of the tribological characteristics of liquid lubricants of various viscosity classes and various groups of operation when using fullerene compositions. Tribological characteristics were evaluated on a four-ball friction machine according to GOST 9490. The use of fullerene compositions in the form of a finely dispersed fullerene powder, pre-dispersed (dissolved) in vegetable high oleic oils, for example, rapeseed, with the subsequent addition of the resulting composition to technical oils of various viscosity classes and various groups of operation, leads to the following positive effect. The anti-wear properties of oils, which are assessed by the wear indicator, increase by 20,0…30,7 %, and the critical load on 18,8…25,0%. These indicators significantly exceed similar indicators when using fullerene fine powders without preliminary dispersion in vegetable oils, where the effect is on the border 11,1…15 %. Fullerene additives do not affect the extreme pressure properties of base oils, which are assessed by the scuffing load. This result makes it possible to state that the way to improve the tribological properties of lubricants by introducing a fine powder of fullerenes into base technical oils is ineffective. The experimental results obtained confirm the hypothesis about the possibility of the micelle formation mechanism in the lubricant under the action of the electrostatic field of the friction surface. The presence of a surfactant solvent (vegetable oil) allows you to "start" the micelle formation process at lower fullerene concentrations and to obtain the effect of increasing anti-wear properties.

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Study on the High-Heat Tribological Characteristics of Lubricating Wear-Resisting Coating Prepared by Supersonic Plasma Spraying

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.80-81.661 ◽

2011 ◽

Vol 80-81 ◽

pp. 661-666

Author(s):

Yun Cai Zhao ◽

Jia Jia Mao ◽

Chun Ming Deng ◽

Wem You Ma

Keyword(s):

High Temperature ◽

Friction Coefficient ◽

Wear Rate ◽

Plasma Spraying ◽

High Heat ◽

The Self ◽

Tribological Characteristics ◽

Wear Properties ◽

Abrasive Resistance ◽

Supersonic Plasma

This paper is about the study of the KF301/WS2composite lubrication wear-resisting coatings prepared by supersonic plasma spraying. Basing on the research of the tribological characteristics, it has been discussed the self-lubricity and the failure mechanism showed by composite lubrication coatings under high-temperature conditions. Research shows that the wear rate of the coatings increased with the increase of the temperature. At 300°C, the wear rate is 1.02×10-4mg/m; At 750°C, the wear rate is 2.61×10-4mg/m. With the increase of temperature, friction coefficient of the coatings shows gradually increasing. When the temperature falls below 600°C, friction coefficient keeps around 0.08; At 750°C, the friction coefficient is 0.12. Temperature has great effect on the friction and wear properties ofthe self-lubricating wear-resisting coatings, mainly manifests in two aspects: first, with the increase of the temperature, under the common influence of thermal stress and frictional contact stress, it promotes the WS2solid lubricant film cracking, breakage, shedding process, and lubrication and abrasive resistance reduces; on the other hand, the WS2occurs chemical reaction under high temperature, generating lubricity phase of NiWO4, CrS, and lubricity phases are well supplied, lubricating film has an effect of continuous lubrication on the rubbing surface, So the coating shows low-friction, and it also represents that the KF-301/ WS2self-lubricating composite coating has good lubrication and abrasive resistance under high temperature．

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Tribological Characterization of Hypereutectic Al–25Si Alloy Under Dry and Lubricated Sliding Conditions

Journal of Tribology ◽

10.1115/1.4036918 ◽

2017 ◽

Vol 140 (1) ◽

Cited By ~ 5

Author(s):

Parveen Kumar ◽

M. F. Wani

Keyword(s):

Wear Rate ◽

Friction And Wear ◽

Normal Load ◽

Experimental Studies ◽

Three Dimensional ◽

Solidification Process ◽

Wear Properties ◽

Sliding Distance ◽

Lubricated Sliding

Friction and wear properties of hypereutectic Al–25Si alloy were studied under dry and lubricated sliding conditions. Hypereutectic Al–25Si alloys were prepared by rapid solidification process (RSP) under the T6 condition. Experimental studies were conducted using a ball on disk type tribometer. The effect of the sliding distance and normal load on the friction and wear were investigated. The coefficient of friction (COF) remained stable with an increase in the sliding distance (250–1500 m) and decreased with an increase in the normal load (10–50 N), whereas the wear rate decreased with an increase in the sliding distance, and increased with the increase in the normal load up to 40 N and then attained a steady-state value under dry and lubricated sliding conditions. The improvements in COF and wear rate were mainly attributed to the morphology, size, and distribution of hypereutectic Si particles due to its fabrication process. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical microscopy, and three-dimensional (3D)-surface profilometer were used for characterization of the wear tracks. The dominant wear mechanisms for a hypereutectic Al–25Si alloy were adhesive wear, abrasive wear, and plastic deformation.

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Effect of High Temperature on Wear Behavior of Stir Cast Aluminium/Boron Carbide Composites

Mechanics and Mechanical Engineering ◽

10.2478/mme-2018-0082 ◽

2020 ◽

Vol 22 (4) ◽

pp. 1031-1046

Author(s):

X. Canute ◽

M. C. Majumder

Keyword(s):

High Temperature ◽

Wear Rate ◽

Boron Carbide ◽

Wear Behavior ◽

Base Alloy ◽

Weight Fraction ◽

Sliding Velocity ◽

Wear Properties ◽

High Temperature Wear ◽

The Matrix

AbstractThe need for development of high temperature wear resistant composite materials with superior mechanical properties and tribological properties is increasing significantly. The high temperature wear properties of aluminium boron carbide composites was evaluated in this investigation. The effect of load, sliding velocity, temperature and reinforcement percentage on wear rate was determined by the pin heating method using pin heating arrangement. The size and structure of base alloy particles change considerably with an increase of boron carbide particles. The wettability and interface bonding between the matrix and reinforcement enhanced by the addition of potassium flurotitanate. ANOVA technique was used to study the effect of input parameters on wear rate. The investigation reveals that the load had higher significance than sliding velocity, temperature and weight fraction. The pin surface was studied with a high-resolution scanning electron microscope. Regression analysis revealed an extensive association between control parameters and response. The developed composites can be used in the production of automobile parts requiring high wear, frictional and thermal resistance.

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Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽

10.3390/ma14154217 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4217

Author(s):

Üsame Ali Usca ◽

Mahir Uzun ◽

Mustafa Kuntoğlu ◽

Serhat Şap ◽

Khaled Giasin ◽

...

Keyword(s):

Weight Loss ◽

Wear Rate ◽

Coefficient Of Friction ◽

Applied Load ◽

Practical Significance ◽

Tribological Characteristics ◽

M 10 ◽

Wide Range ◽

The Coefficient Of Friction ◽

Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

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Implementation Intentions to Reduce Smoking: A Systematic Review of the Literature

Nicotine & Tobacco Research ◽

10.1093/ntr/ntaa235 ◽

2020 ◽

Author(s):

Charlotte J Hagerman ◽

Rebecca K Hoffman ◽

Sruthi Vaylay ◽

Tonya Dodge

Keyword(s):

Systematic Review ◽

Implementation Intentions ◽

Experimental Studies ◽

Implementation Intention ◽

Promising Tool ◽

Current Systematic Review ◽

Long Term Follow Up ◽

Positive Effect

Abstract Implementation intentions are a goal-setting technique in which an individual commits to perform a particular behavior when a specific context arises. Recently, researchers have begun studying how implementation intention (II) interventions can facilitate antismoking efforts. The current systematic review synthesized results of experimental studies that tested the effect of an II intervention on smoking cognitions and behavior. Of 29 reviewed articles, 11 studies met inclusion criteria. Nine studies (81.8%) tested an II intervention as a cessation tool for current smokers, whereas two tested II interventions as a tool to prevent smoking among predominantly nonsmoking adolescents. A majority of the studies (66.7%) testing II interventions as a cessation tool reported a positive effect on cessation at long-term follow-up. Of the two studies testing II interventions as a tool for prevention, one study found a positive effect on long-term follow-up. Methodology varied between the studies, highlighting the discrepancies between what researchers consider “implementation intentions” to be. II interventions are a promising tool for antismoking efforts, but more research is necessary to determine the best methodology and the populations for whom this intervention will be most effective. Implications Brief, free, and easily scalable, II interventions to prevent smoking are highly attractive for antismoking efforts. This review outlines the circumstances under which II interventions have demonstrated effectiveness in helping people resist smoking cigarettes. We illuminate gaps in the existing literature, limitations, methodological discrepancies between studies, and areas for future study.

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Mechanical and Microstructural Characterization of Friction Stir Welded SiC and B4C Reinforced Aluminium Alloy AA6061 Metal Matrix Composites

Materials ◽

10.3390/ma14113110 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3110

Author(s):

Kaveripakkam Suban Ashraff Ali ◽

Vinayagam Mohanavel ◽

Subbiah Arungalai Vendan ◽

Manickam Ravichandran ◽

Anshul Yadav ◽

...

Keyword(s):

Wear Rate ◽

Aluminium Alloy ◽

Metal Matrix Composites ◽

Metal Matrix ◽

Weld Zone ◽

Base Material ◽

Matrix Composites ◽

Wear Properties ◽

Friction Stir ◽

Behavioural Aspects

This study focuses on the properties and process parameters dictating behavioural aspects of friction stir welded Aluminium Alloy AA6061 metal matrix composites reinforced with varying percentages of SiC and B4C. The joint properties in terms of mechanical strength, microstructural integrity and quality were examined. The weld reveals grain refinement and uniform distribution of reinforced particles in the joint region leading to improved strength compared to other joints of varying base material compositions. The tensile properties of the friction stir welded Al-MMCs improved after reinforcement with SiC and B4C. The maximum ultimate tensile stress was around 172.8 ± 1.9 MPa for composite with 10% SiC and 3% B4C reinforcement. The percentage elongation decreased as the percentage of SiC decreases and B4C increases. The hardness of the Al-MMCs improved considerably by adding reinforcement and subsequent thermal action during the FSW process, indicating an optimal increase as it eliminates brittleness. It was seen that higher SiC content contributes to higher strength, improved wear properties and hardness. The wear rate was as high as 12 ± 0.9 g/s for 10% SiC reinforcement and 30 N load. The wear rate reduced for lower values of load and increased with B4C reinforcement. The microstructural examination at the joints reveals the flow of plasticized metal from advancing to the retreating side. The formation of onion rings in the weld zone was due to the cylindrical FSW rotating tool material impression during the stirring action. Alterations in chemical properties are negligible, thereby retaining the original characteristics of the materials post welding. No major cracks or pores were observed during the non-destructive testing process that established good quality of the weld. The results are indicated improvement in mechanical and microstructural properties of the weld.

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Tribological behavior of AZ91D magnesium alloy composite: effect of hybrid WC – SiO2 nanoparticles

Industrial Lubrication and Tribology ◽

10.1108/ilt-02-2021-0038 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Mohammed Fahad ◽

Bavanish B.

Keyword(s):

Magnesium Alloy ◽

Wear Rate ◽

Az91d Alloy ◽

Hybrid Particles ◽

Wear Properties ◽

Sliding Speed ◽

Composite Effect ◽

Content Type ◽

Climate Conditions ◽

Az91d Magnesium Alloy

Purpose Aviation field requires a material with greater tribological characteristics to withstand the critical climate conditions. Hence, it is of paramount importance to enhance the wear resistance of material. AZ91D magnesium alloy is a light weight material used in the aviation field for the construction work. The purpose of this study is to augment the wear properties of AZ91D alloy by reinforcing with hard particles such as tungsten carbide (WC) and silicon dioxide (SiO2). Design/methodology/approach In this work, three types of composites were fabricated, namely, AZ91D – WC, AZ91D – SiO2 and AZ91D – (WC + SiO2) by ball milling method, and the tribological properties were analyzed using pin-on-disc apparatus. Findings Results showed that the hardness of AZ91D alloy was greatly improved due to the reinforcing effects of WC and SiO2 particles. Wear study showed that wear rate of AZ91D alloy and its composites increased with the increase of applied load due to ploughing effect and decreased with the increase of sliding speed owing to the formation of lubricating tribolayer. Further, the AZ91D – (WC + SiO2) composite exhibited the lower wear rate of 0.0017 mm3/m and minimum coefficient of friction of 0.33 at a load of 10 N and a sliding speed of 150 mm/s due to the inclusion of hybrid WC and SiO2 particles. Hence, the proposed AZ91D – (WC + SiO2) composite could be a suitable candidate to be used in the aviation applications. Originality/value This work is original which deals with the effect of hybrid particles, i.e. WC and SiO2 on the wear performance of the AZ91D magnesium alloy composites. The literature review showed that none of the studies focused on the reinforcement of AZ91D alloy by the combination of carbide and metal oxide particles as used in this investigation.

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Development of High Performance (Mechanical and Wear Properties) of AA 6061-Hybrid Nano Composites Via Liquid Metallurgy Route

Al-Nahrain Journal for Engineering Sciences ◽

10.29194/njes.22020143 ◽

2019 ◽

Vol 22 (2) ◽

pp. 143-150

Author(s):

Hussain J. M. Al-Alkawi ◽

Abduljabbar Owaid Hanfesh ◽

Saja Mohammed Noori Mohammed Rauof

Keyword(s):

Tensile Strength ◽

Ultimate Tensile Strength ◽

Wear Rate ◽

Yield Strength ◽

Base Metal ◽

Young Modulus ◽

Nano Particles ◽

Wear Properties ◽

Constant Weight ◽

Weight Percentage

This research is devoted to study the influence of different weight percent concerning to the additions of Ti and Cu on mechanical and tribological properties of AA6061. The composite materials consist of different weight percentage of Ti (0.2, 0.4, and 0.6) wt% and constant weight percentage of Cu (0.2) wt% which were fabricated by liquid metallurgy route technique. Microstructural characterization and phases have been examined by using SEM (scanning electron microscopic).SEM examination showed uniform distribution of nano Ti and Cu in AA6061. The consequences of mechanical tests demonstrated clear enhancement in mechanical properties, such as ultimate tensile strength, yield strength, young modulus, ductility% and hardness at additive percentage of 0.4% Ti+0.2%Cu nano particles incorporated into molten AA6061. Percentage of enhancement ultimate tensile strength is about 73.3%, yield strength about 82.7%, young modulus is about 21.2%, the Vickers hardness about 42.6% and the decreasing in ductility was about 25.2% compared with the metal matrix (AA6061). The wear rate test was performed by using pin on disc rig for both hybrid nano composite and base metal (AA6061) under various loads (10,15and 20) N with sliding speed (1.282) m/sec at a (10) min’s time. The results showed a decrease in wear rate at 0.4%Ti+0.2%Cu compared with the base metal (AA6061). Improvement percentage of wear rate is about 105% at 20 N load.

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Influence of load and reinforcement content on selected tribological properties of Al/SiC/Gr hybrid composites

Production Engineering Archives ◽

10.30657/pea.2018.18.03 ◽

2018 ◽

Vol 18 (18) ◽

pp. 18-23 ◽

Cited By ~ 3

Author(s):

Sandra Veličković ◽

Slavica Miladinović ◽

Blaža Stojanović ◽

Ružica R. Nikolić ◽

Branislav Hadzima ◽

...

Keyword(s):

Aluminum Alloy ◽

Friction Coefficient ◽

Wear Rate ◽

Tribological Properties ◽

Metal Matrix ◽

Hybrid Composites ◽

Tribological Characteristics ◽

Volume Fractions ◽

Sic Particles ◽

The Matrix

Abstract Hybrid materials with the metal matrix are important engineering materials due to their outstanding mechanical and tribological properties. Here are presented selected tribological properties of the hybrid composites with the matrix made of aluminum alloy and reinforced by the silicon carbide and graphite particles. The tribological characteristics of such materials are superior to characteristics of the matrix – the aluminum alloy, as well as to characteristics of the classical metal-matrix composites with a single reinforcing material. Those characteristics depend on the volume fractions of the reinforcing components, sizes of the reinforcing particles, as well as on the fabrication process of the hybrid composites. The considered tribological characteristics are the friction coefficient and the wear rate as functions of the load levels and the volume fractions of the graphite and the SiC particles. The wear rate increases with increase of the load and the Gr particles content and with reduction of the SiC particles content. The friction coefficient increases with the load, as well as with the SiC particles content increase.

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