Good Lubricating Properties Research Articles

Electrochemical Corrosion Behavior of Magnetron-Sputtered Al-Mo Gradient-Coated Steel in 3.5 wt.% NaCl Solution

A gradient three-layer Al-Mo coating was deposited on steel using magnetron sputtering method. The corrosion properties of the coating were studied in 3.5 wt.% NaCl solution using electrochemical techniques, whereas the hydrogen-induced cracking (HIC) resistance was examined by constant-load tests using notched tensile specimens. These results were compared with conventional electroplated cadmium-coated steel. The results show that the gradient Al-Mo coating exhibits better corrosion and HIC resistance when compared to electroplated cadmium. This was due to the excellent corrosion resistance of the bottom aluminum-rich layer, while the top Mo-rich layer provided good lubrication properties.

On the Tribological Performance of Vegetal Lubricants: Experimental Investigation on Jatropha Curcas L. oil

The limited resources of petroleum-based lubricants and increased environmental contamination, that they produce, lead to increased demand for bio-lubricants. Due to several factors such as biodegradability, good lubricating properties and low production costs, the plant oils represent a good alternative as reference to replace the petroleum-based oils. Obviously, the need to ensure the use of vegetable oils as a source of food makes non-edible vegetable oils a formidable source for plant oil lubricants. Thus, the toxicity of Jatropha Curcas L. oil makes it a very attractive and alternative lubricant source. Therefore, the aim of this work is to investigate on tribological performance of Jatropha Curcas L. oil in the lubricating contact pair AISI 52100 steel sliding against X210Cr12 steel. The experimental tests were carried out using ball-on-flat reciprocatory tribometer for several frequencies and with normal load of 12N. The Jatropha Curcas L. oil was analyzed for its chemical and physical properties such as viscosity, density and flash point. The results were interpreted on the basis of the evolution of the friction coefficient. The evolution of the friction coefficient was monitored for 40min in all tests. The results show that the friction coefficient decreases with the increase of the frequency, and the final value stays in the range of 0.04-0.122.

Bioinspired lubricating films of cellulose nanofibrils and hyaluronic acid

The development of materials that combine the excellent mechanical strength of cellulose nanofibrils (CNF) with the lubricating properties of hyaluronic acid (HA) is a new, promising approach to cartilage implants not explored so far. A simple, solvent-free method to produce a very lubricating, strong cellulosic material by covalently attaching HA to the surface of CNF films is described in this work. A detailed analysis of the tribological properties of the CNF films with and without HA is also presented. Surface and friction forces at micro/nanoscale between model hard surfaces (glass microspheres) and the CNF thin films were measured using an atomic force microscope and the colloid probe technique. The effect of HA attachment, the pH and the ionic strength of the aqueous medium on the forces was examined. Excellent lubrication was observed for CNF films with HA attached in conditions where the HA layer was highly hydrated. These results pave the way for the development of new nanocellulose-based materials with good lubrication properties that could be used in biomedical applications.

Renewable fuels and lubricants from Lunaria annua L.

A non-edible fatty oil coming from Lunaria annua plant (honesty plant) was investigated as a starting material for the sequential production of biodiesel (fatty acid methyl esters—FAME) and biolubricants (trimethylolpropane esters). Lunaria oil constitutes an attractive feedstock because of its unusual fatty acid profile comprising mainly of erucic (22:1) and nervonic (24:1) acid. For the production of the desired biobased products, the following transesterification methodology was applied. At first, Lunaria oil was converted to the corresponding methyl esters via methanolysis reaction and the produced FAME was assessed as automotive fuel according to the specified requirements and test methods included in the European Standard EN14214. In order to synthesize the environmentally adapted lubricants, part of the previously prepared methylesters was converted to trimethylolpropane (TMP) esters via alkaline transesterification reaction. Lunaria TMP esters were evaluated as potential lubricant basestock regarding their physicochemical properties and their lubricating performance. Concerning fuel properties, Lunaria methyl esters appear to satisfy the majority of the EN14214 requirements with the exception of kinematic viscosity due to the high content of long chain fatty acids. However, the later could be counterbalanced though blending with other types of low quality feedstock. On the other hand, the high monounsaturated content is beneficial to other properties such as oxidation stability. The synthesized TMP esters demonstrate very good lubricating properties as well as oxidation stability, and thus, they could be utilized as lubricant basestock in the formulation of high added value biolubricants for special and environmentally sensitive applications. As a whole, Lunaria oil appears to be an interesting feedstock for the production of biodiesel and especially biobased lubricant basestock.

Enhancing the Anhydrous Proton Conductivity of Sulfonated Polysulfone/Polyvinyl Phosphonic Acid Composite Membranes With Hexagonal Boron Nitride

Hexagonal boron nitride (h-BN) particles have attracted increasing interest due to mechanical properties, chemical stability, electrical features, thermal stability, and good lubrication property. In this work hexagonal boron nitride were used as inorganic fillers, which increase the mechanical and thermal stabilities of the membrane. The proton conducting polymer membranes were prepared by blending of sulfonated polysulfone, polyvinyl phosphonic acid, and boron nitride. Scanning electron microscopy indicated the homogeneous distribution of hBN nanoparticles in the polymer matrix. hBN increased the proton conductivity and in the anhydrous state the maximum proton conductivity was determined as 7.9 × 10−3 S/cm at 150°C for PVPA-SPSU-5hBN.

Experimental and Numerical Analysis of Vibration of the Test Stand

Sound effect derives a pair of highly loaded machinery parts-motion screw and nut. Loaded pair is used in non-standard environments of high voltage electrical equipment in electrical substations. The non-standard environment is seen in the movement of this pair immersed in transformer oil deeply below the surface. Transformer oil has no good mechanical lubricating properties because it does not contain sulfur. Loaded pair cannot be lubricated, because there would be oil contamination and deterioration of its electro-insulating properties. The causes were sought in the structure of the machine, frame stiffness, mechanical strength machine and used materials. The aim of the research with help experimental and numerical study was to define the cause and eliminate sound effect coming from the device.

Influence of Microalgal Bio-Oil on the Lubrication Properties of Engine Oil

In order to accelerate and expand the application of bio-energy, two kinds of microalgal bio-oils, prepared via co-liquefaction of Chlorella and Spirulina under sub- and supercritical ethanol conditions, were used as partial substitutes for the engine oil CD SAE 15W-40. The friction and wear behaviors of the oils were tested on a four-ball tribometer, referring to the ASTM D4172 standard conditions. The micro-morphology, profiles, roughness and chemical valences of typical elements on the rubbed surfaces were characterized by Scanning Electron Microscopy (SEM), surface profiler and X-ray Photoelectron Spectroscopy (XPS), respectively. The results showed that both of the bio-oils had good lubrication properties. The suitable weight content of the bio-oils in the engine oil was 10%. The lubrication properties of the Bio-Oil (BOsup) prepared in supercritical ethanol were a little better than those of the Bio-Oil (BOsub) prepared in subcritical ethanol. The lubricating mechanisms were ascribed to the combined actions of various lubricating films, including boundary lubrication, and deposited films and tribological chemical reaction films. The stronger tribological chemical effects of BOsup from higher contents of N-containing compounds contributed to its better lubrication properties than those of BOsub.

The Potential of Microalgal Biodiesel in Turkey

Turkey has limited petroleum reserves which causes the country to become a foreign dependent in respect to energy. As a result, the dependency level of Turkey on foreign fossil fuel suppliers reaches around 70%. Biodiesel, which has a more favorable combustion emission profile, relatively high flash point, and good lubrication properties, can be an effective alternative energy source. However, to provide the necessary amount of oil from agricultural products may affect food production and require a high amount of water and fertilizer. With their high oil content and high productivity rates, microalgae seems to be the best source of fuel which can replace petroleum products totally. This article introduces methods of microalgae production and discusses the potential of Turkey to pass microalgal biodiesel technology.

Investigation on the Potential of Dextrose, Sucrose and Cellulose Dodecenylsuccinate Esters as Lubricity Additive

As a consequence of the environmental issues and the increasing global demand of the lubricants, we need to have the sustainable raw material sources not only for the lube base oil but also for additives. In view of this, we have synthesized the dodecenylsuccinate (DDSA) ester of dextrose (sample 1), sucrose (sample 2) and cellulose (sample 6) with almost same degree of substitution (DS ~2.0). The lubricity was observed for these synthesized samples in n-decane which was taken as lubricant reference base fluid. The lubricity tests were carried out as per the ASTM D6079 using high frequency reciprocating test rig. It was observed that the dextrose-DDSA ester shows good lubricity properties in comparison to sucrose and cellulose. 1 % sucrose-DDSA in n-decane has decreased the value of wear scar diameter from 800 to 515 µm while the values for sucrose-DDSA and cellulose-DDSA were found to be 565 and 590 µm respectively. Further, to see the effect of varying DS over the lubricity in the case of cellulose-DDSA esters, the four cellulose ester samples (sample 3–6) with varying DS (0.68, 0.95, 1.43 and 2.03) were prepared and evaluated. It was also observed that the lubricity increases with the increasing DS value in cellulose-DDSA esters.

Self-lubricating CrVN Coating Strengthened via Multilayering with VN

To improve the mechanical properties of self-lubricating chromium vanadium nitride (CrVN) coatings, vanadium nitride (VN) is combined with CrVN to form multilayered CrVN/VN coatings through an in-line magnetron sputtering system. The strengthening effect of the period thickness on the mechanical and tribological properties is studied. X-ray diffractometer, low-angle X-ray reflectivity, scanning electron microscopy, atomic force microscopy, electron probe micro-analyzer and X-ray photoelectron spectroscopy are employed to characterize the microstructures and chemical composition. Nanoindentation and ball-on-disc tribo-tester are used in characterization of the mechanical and tribological properties. The CrVN/VN multilayer coatings demonstrate good lubrication property with coefficient of friction down to 0. 23. Multilayering with VN, the hardness of CrVN jumps to 27. 6 GPa with period thickness of 6 nm, which has an improvement of 5. 1 GPa compared with that of 22. 5 GPa from rule-of-mixture.

Investigation of Wear Behaviour ZA 27 Using Bio-Lubricants

— The Zinc–Aluminium (ZA) family of casting alloys are gaining wide commercial importance as journal bearing material for high load and low speed applications. These alloys, most notably ZA-27 is capable of replacing traditional bronze bearing at low cost. Recently, the ZA-27 alloy has been substituted for conventional journal bearing materials in a wide range of industrial applications. The journal bearings produced from these alloys have been used in earthmoving equipments, mining and milling machines, cable winches and compressors. The ZA-27 alloys and the bearings were also used in heavy and dusty environments such as underground machines, ore crashers and rock drills.The tribological properties of the ZA 27 alloy were tested using a Pin-on-Disc friction and wear tribotester.Sliding wear tests were performed using the tribotester by varying load, speed & sliding distance. The same tests are done with lubricating condition and also with bio lubricants. The Bio-lubrication is adopted in this work because of its biodegradability and eco-friendly nature. Especially the soya bean oil possess good lubrication properties. The wear rate of dry, base oil and bio lubricant oil condition were determined different applied load, speed and sliding distance compared with each other.

The prospects of biolubricants as alternatives in automotive applications

Lubricants perform as anti-friction media. They facilitate smooth operations, maintain reliable machine functions, and reduce the risks of frequent failures. At present, the increasing prices of crude oil, the depletion of crude oil reserves in the world, and global concern in protecting the environment from pollution have renewed interest in developing and using environment-friendly lubricants derived from alternative sources. A biolubricant is renewable lubricants that is biodegradable, non-toxic, and emits net zero greenhouse gas. This study presents the potential of a biolubricant based on vegetable oil as an alternative lubricant according to studies published in highly rated journals in scientific indices. In the first part of this paper, the source, properties, as well as advantages and disadvantages of the biolubricant are discussed. The second part describes the potential of vegetable oil-based biolubricants as alternative lubricants for automobile applications. The final part describes the world biolubricant market and its future prospects. Biolubricants are potential alternative lubricants because of their low toxicity, good lubricating properties, high viscosity index, high ignition temperature, increased equipment service life, high load-carrying abilities, good anti-wear characteristic, excellent coefficient of friction, natural multi-grade properties, low evaporation rates, and low emissions into the atmosphere.

Experimental research on tribological performance of water-based rolling liquid containing nano-TiO2

Nano-TiO2 was dispersed in water to study the influences of nanoparticles on the tribological properties of water-based rolling liquid for hot steel. The phase composition and microstructure of nano-TiO2 were investigated by X-ray diffraction and transmission electron microscopy methods. The friction reduction and antiwear properties were measured on a four-ball friction tester, and then hot rolling experiments with lubrication have been carried out. The rolling force and surface roughness were measured. Moreover, the surface elements of the steel lubricated by nano-TiO2 rolling liquid were analyzed by energy dispersive spectroscopy. The results showed that nano-TiO2 as water-based liquid additives can effectively improve the antiwear properties of steel–steel friction pair and reduce the friction coefficient. At the same time, nano-TiO2 shows good lubrication properties during hot rolling. It is inferred from the lubrication and repairing mechanism that TiO2 nanoparticles sediment on the surface of steel, and the lower surface film is formed under high temperature and high pressure. The film possesses excellent antiwear, friction-reducing and repair properties.

Ionic liquids from amino acids: fully green fluid lubricants for various surface contacts

Five tetrabutylammonium-based amino acid ionic liquids (AAILs), tetrabutylammonium serine ([N4444][Ser]), tetrabutylammonium threonine ([N4444][Thr]), tetrabutylammonium valine ([N4444][Val]), tetrabutylammonium leucine ([N4444][Leu]) and tetrabutylammonium lysine ([N4444][Lys]) have been easily prepared by the neutralization of tetrabutylammonium hydroxide ([N4444][OH]) with the five corresponding amino acids. These AAILs only contain the elements C, N, O and H in their structures, so they are more environmentally friendly than conventional phosphorus-, halogen- or sulfur-containing lubricants. The preparation process of these AAILs is simple and also fully green, because no other by-products except water were produced during the whole process. The AAILs were evaluated as green lubricants for various surface contacts, such as steel/steel, steel/copper and steel/aluminum, using an Optimol SRV-IV oscillating reciprocating friction and wear tester at room temperature (RT). Due to their halogen-free character, these AAILs have a higher hydrolysis stability and a far lower corrosion level than the halogen-containing lubricants imidazolium ILs, 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6mim][NTf2]), which were also tested. The tribotest results revealed that these AAILs could act as lubricants to effectively reduce friction and wear of all sliding pairs, and they even showed superior tribological performances compared to poly-alpha-olefin (PAO40) and [C6mim][NTf2] under the experimental conditions. The worn surfaces of the lower discs were analyzed by X-ray photoelectron spectrometry (XPS). Based on the XPS results, it can be concluded that the good lubricating properties of the AAILs are attributed to the formation of physically adsorbed layers on the metal surfaces during the rubbing process.

Evaluation of ionic fluids as lubricants in manufacturing

Ionic fluids are liquid salts that have been investigated for a number of applications, including catalysis, their use as solvents and electrically conducting fluids. Chemically, they consist of ionically bonded species, and depending on the cation and anion, can be extremely valuable in the chemical processing industry. Another characteristic that makes them useful is a high viscosity and good lubrication properties. This paper examines a number of ionic fluids, and determines their suitability as lubricants. This involves determining rheological properties, including viscosity and high-pressure viscosity, generally using a Barus law. In addition, their traction behavior is measured to evaluate their lubricating properties. Since metalworking fluids (and lubricants in general) are used in non-isothermal situations, the thermal conductivity of these fluids have also been measured.

Research on the microstructure and space tribology properties of electric-brush plated Ni/MoS2–C composite coating

In order to expand the application field of MoS2 lubricant coatings (films) and to improve their adaptability in harsh environments, a Ni/MoS2–C composite coating composed of Ni metallic matrix and two lubricating components was prepared on AISI 52100 steel substrates with a nano electro-brush plating process. The relationship between microstructure and properties of the coating was analyzed via microstructure characterization. The tribological properties of the as-received coating samples and the samples treated in humid air (HA), high vacuum (HV), atomic oxygen (AO) erosion and ultraviolet (UV) irradiation exposure were investigated comparatively. The results show that the surface of the obtained Ni/MoS2–C coating is smooth and clean. The micro and nano MoS2–C grains are dispersed in the Ni matrix homogeneously. The MoS2 and C particles also showed good synergistic effects. The added nano graphite particles not only increased the moisture resistance of the composite coating, but also reduced the residual stress and enhanced the mechanical properties of the coating. The composite coating still showed good lubricating properties after long-duration treatments in HA, HV, AO and UV environments, and the friction coefficients during the stable running periods remained at about 0.1. The influence of vacuum outgassing on the properties of the lubricants is not obvious. The coatings were oxidized slightly by AO, and thus their initial friction coefficients in AO conditions also increased, but the coating still showed good friction reduction properties after a short running-in period. The changes in microstructure and properties of the coating after UV irradiation were also inconspicuous. All test results indicate that the Ni/MoS2–C composite coating has excellent space tribological properties and good adaptability in harsh environments. So it is promising to use Ni/MoS2–C composite coating in a space solid lubrication area.

Tribological behaviour of proposed polymeric bearing materials

AbstractThe aim of the present work is to introduce new polymeric bearing materials. The proposed polymeric composites are consisting of polyethylene (PE), polypropylene (PP) and polystyrene (PS) and filled by fibres of polytetrafluoroethylene (PTFE) in concentration up to 25 wt.% as well as different types of natural oils such as (corn oil, olive oil, paraffin oil, glycerin oil, castor oil and sunflower oil) in concentration up to 10 wt.%. The frictional behavior of the proposed composites and wear resistance are investigated at different values of applied load. Based on the experimental observations, it was found that for composites free of oil, friction of PS and PE specimens decreased, while friction of PP specimens slightly increased with increasing PTFE content. PP composites filled by corn oil showed slight friction increase. Besides, friction coefficient displayed by PS and PE specimens filled by glycerin oil decreased with increasing oil content, while friction coefficient displayed by PP specimens showed consistent trend. It was noted that, PE filled with 7.5% glycerin oil and 20 wt.% PTFE displayed the minimum value of friction coefficient (0.07). This friction coefficient values recommend those composites to be used as bearing materials. PE filled by glycerin oil displayed relatively lower friction values due its common known good lubricating property. Friction of PE composites filled by paraffin oil drastically decreased with the increasing oil content. PP composites showed the lowest wear values. In addition to that, it was shown that wear displayed by composites filled by glycerin oil was higher than that containing corn oil, while wear of the tested composites filled with olive oil showed lower values than that displayed by corn oil filled composites. Composites containing 5.0–7.5% paraffin oil content showed good wear resistance which recommends them to be used as bearing material. Wear of PP, PS and PE composites filled with sunflower oil and 15 wt.% PTFE drastically decreased with increasing oil content. The minimum wear was displayed by PP and PE composites filled with 10% oil content.

Beam Assisted Deposition Film for Improving Fretting Fatigue Resistance of Ti-8Al-1Mo-1V Alloy at Elevated Temperature

Ion-beam-assisted deposition (IBAD) was investigated as a potential way to increase the fretting fatigue resistance of Ti-8Al-1Mo-1V alloy at elevated temperature. Three coating systems, hard TiN film, Al film and Cu/Ni multilayer films have been applied on the base material. Coefficients of friction and fretting fatigue lives of the specimens with and without film were compared. The results indicate that the IBAD technique can prepare all films with high bonding strength and excellent lubricating properties. The fretting fatigue life of the Ti-8Al-1Mo-1V alloy with the TiN film was improved by a factor of 2.4 as compared to the uncoated substrate at elevated temperature because of the excellent wear and fatigue resistance and good toughness of the film. The IBAD Al film significantly improved the fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy at elevated temperature for good lubricating property. The fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy was improved by all the Cu/Ni multilayer films. However, the fretting fatigue resistance did not increase monotonically with the modulation period of the films.

Beam Assisted Deposition Film for Improving Fretting Fatigue Resistance of Ti-8Al-1Mo-1V Alloy at Elevated Temperature

Ion-beam-assisted deposition (IBAD) was investigated as a potential way to increase the fretting fatigue resistance of Ti-8Al-1Mo-1V alloy at elevated temperature. Three coating systems, hard TiN film with good toughness and soft Al film of low friction and Cu/Ni multilayer films with modulation period thickness of 20~600nm have been applied on the base material. Coefficients of friction and fretting fatigue lives of the specimens with and without film were compared. The film damage was characterized through scanning electron microscopy. The results indicate that the IBAD technique can prepare all films with high bonding strength and excellent lubricating properties. The fretting fatigue life of the Ti-8Al-1Mo-1V alloy with the TiN film was improved by a factor of 2.4 as compared to the uncoated substrate at elevated temperature because of the excellent wear and fatigue resistance and good toughness of the film. Excellent wear resistance and good anti-fatigue properties could be simultaneously obtained by a single hard film to control the fretting fatigue damage. The IBAD Al film significantly improved the fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy at elevated temperature for good lubricating property. The fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy was improved by all the Cu/Ni multilayer films. However, the fretting fatigue resistance did not increase monotonically with the modulation period of the films. Films with a modulation period of 200 nm had the highest fretting fatigue resistance among the multilayer films prepared owing to their high toughness and strength and good lubricating and anti-fatigue action. The fretting fatigue resistance of films with a modulation period of 20 nm was low because of the poor fracture toughness and crack propagation resistance, even though these films had the highest hardness and good fretting wear resistance. Thus, comprehensive properties, including high toughness and strength, must be considered for multilayer films used to improve the fretting fatigue resistance of titanium alloys.

Preparation of poly (N-isopropylacrylamide) brush bonded on silicon substrate and its water-based lubricating property

The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by ellipsometer) with a grafting density of ca. 0.27 chains/nm2. The tribological properties of the poly (N-isopropylacrylamide) brush were investigated by means of ball-on-disk tests in a rotational mode under water lubrication for tribological application. The experimental results exhibited a low friction coefficient of ca. 0.03. The excellent lubrication property of the brush was due to its amide groups in the polymer chains. It was supposed that the good lubrication property of the brush was attributed to the cross-linked polymer network formed by the hydrogen bond association of N—H…O==C and the water molecular layer adsorbed by the terminal amide groups in the brush. The poly (N-isopropylacrylamide) solution also exhibits a lubrication property due to physical adsorption of the polymer chains.