Good Anti-wear Properties Research Articles

TRIBOLOGICAL TESTING OF ENVIRONMENTALLY FRIENDLYLUBRICANTS

This paper compares the properties of mineral oil with glycerol and water-based oil, and rapeseed-based oil.The obtained research results showed that the friction coefficient for mineral oil has similar characteristics forboth loads (25 N/50 N). Minimal differences were also observed for the rapeseed-based oil. However, the mostsignificant difference was obtained for oil based on glycerol and water, where the friction coefficient increasedby more than 23% under the load of 50 N compared to 25 N. The tests showed very good characteristicsof the oils based on rapeseed oil and the oil based on glycerol and water with additives reducing friction,depending on the applied load. For lower loads, the oil based on glycerol and water has very good anti-wearproperties, whereas the oil based on rapeseed oil has very good anti-wear properties for higher loads. Thus,environmentally friendly oils have similar or better lubricating properties under appropriate conditions thantoxic oils with high additive contents. Hence, they have the potential to replace the commonly used mineraloil.

A review on bio-based feedstock, synthesis, and chemical modification to enhance tribological properties of biolubricants

Biolubricants are emerging as an alternate option to petroleum-based lubricants and seeking the attention of researchers worldwide due to their biodegradability, renewability, and non-toxic nature. The presence of various acids such as oleic acid, ricinoleic acid, and linoleic acid enables the conversion of vegetable oil into biolubricants with desired lubricating properties. The addition of nanoparticles may ensure good anti-wear properties and proper viscosity of biolubricants. Transesterification, epoxidation, and estolide formation are the main method of the synthesis of the biolubricants from vegetable oil. This paper reviews the state–of–art development of the biolubricants, vegetable oil as feedstock for the biolubricants, and physico-chemical properties of biolubricants for better lubrication considering the improvement in chemical properties and methods of production. Chemical modification and the use of nanomaterial to improve the quality of the biolubricants have been reviewed in this paper. This paper will provide complete insight into the recent development of biolubricants to researchers working in the field of tribology and lubrication.

Microstructure evolution and anti-wear mechanism of Cu film fabricated by magnetron sputtering deposition

Copper (Cu) film was fabricated by magnetron sputtering method, and then subjected to current-carrying friction experiments in this study. Plastic deformations were found in the surface of the wear scar. Focused Ion Beam (FIB) cutting technology was firstly used combined with the Electron Backscattered Diffraction (EBSD) to analyze the worn surface, and the results indicated that the original grains would be broken down into smaller grains during friction. Owing to the strengthening effect of grain refinement, the Cu film exhibited good anti-wear properties. The TEM pattern revealed that the Cu Columnar crystals grow along the direction of magnetron sputtering deposition and perpendicular to the direction of reciprocating friction. GP zones and Nano-twins were observed at the polar surface, and the GP zones would gradually transform to stacking faults structures during the friction.

Ashless and non-corrosive disulfide compounds as excellent extreme pressure additives in naphthenic oil

Medium chain chlorinated paraffin (MCCP) and zinc dialkyl dithiophosphate (ZDDP) are widely used as extreme pressure (EP) additives in metalworking fluids (MWFs). Currently, sulfur-based EP additives are found to be more environmentally friendly and biodegradable. Although naphthenic base oil (NBO) is suitable to be used in MWFs due to its low pour point and better emulsified ability, there is a lack of study on the sulfur additives in this type of oil. In this study, two organo disulfides compounds namely dibenzyl disulfide (DBDS) and dioctyl disulfide (DODS) have been synthesized as EP additives. These DBDS and DODS demonstrate an excellent EP performance, non-corrosive, ashless, and good anti-wear (AW) properties in NBO. The DBDS shows 1961 N (EP value) and 6 mm2 (AW scar area) in NBO, which is superior to DODS, MCCP and ZDDP. This is due to the formation of sulfur-based tribofilm on the interface that acts as a protective sulfur layer thus, enhancing the property of EP.

Ароматические углеводороды азербайджанских нефтей и их влияние на эксплуатационные характеристики смазочных масел

. The production of high-quality motor oils is carried out using base oils of the II and III groups by API, hydrocracking and hydroisomerization oils, IV group oils and synthetic oils. Synthetic oils are considered the best oils, but they have some disadvantages: they contain isoparaffinic hydrocarbons, their low polarity or its complete absence creates insufficient adhesion of the oil to metal surfaces and the oil flows into the crankcase. These disadvantages are leveled by the addition of 5-10% synthetic alkylnaphthalenes to the oil. The article presents the qualities of motor oils from the developed at the Institute of Petrochemical Processes of ANAS, where a highly refined base oil (15-65%) from Balakhany oil, containing natural alkyl-naphthalenes (3-5%) and a concentrate of Lubrizol additives, was used as the base component. Sample testing was carried out at the Forschungszentrum (FVTR GmbH), which is a recognized scientific center in the field of energy technology, the center has a high level of expertise and direct access to new results and trends in international research. The samples have been shown to have good antiwear and antioxidant properties, according to these indicators, at the level of Mobil 1×1 5W30 oil containing synthetic AN.

Tribological properties of duplex coatings of chromium-vanadium carbide produced by thermo-reactive diffusion (TRD)

Carbide coatings are very important in molding industries due to their good anti-wear properties increasing the life of molds of hot and cold forging, extrusion and powder metallurgy exposing to abrasive forces. Diverse processes are applied to produce carbide coatings. One of them is the thermo-reactive diffusion method (TRD) using a molten salt bath. This process has many advantages including cost-effectiveness over other similar surface coating methods. The aim of this study is the formation of carbide-composite coatings using molten salt baths containing oxides of carbide forming elements individually and in a mixed form on SKD-11 cold work tool steel at 1000 °C. For this purpose, two sets of experiments were considered in this study. In experiment A, a chromium oxide bath and then a mixed chromium oxide and vanadium oxide bath with a molar ratio of Cr to V equal to 0.66 were used. In experiment B, at first a mixed chromium oxide and vanadium oxide bath (Cr/V ratio = 0.66) and next a single bath of vanadium oxide were utilized. To evaluate and compare the produced coatings, FE-SEM, EPMA (point, line and map), XRD analysis, nano-indentation and wear tests were performed. The results showed that the coatings include chromium carbides (Cr3C2, Cr7C3 and Cr23C6) and vanadium carbides (V2C, V6C5 and V8C7) as well as a carbon-chromium-vanadium triple phase with the composition of Cr2C2V. Moreover, the best hardness and abrasion resistance were gained for the coating produced in the molten bath containing chromium oxide and vanadium oxide after experiencing a chromium oxide bath. For the sample, the hardness was between 17.2 and 19.6 GPa and the lowest amount of COF was 0.32.

Moringa Oil With Pristine and Fluorinated Carbon Nanofibers as Additives for Lubrication

Abstract This study focuses on the influence of local moringa oil on the performances of lubricants obtained from a blend of dodecane and pristine or fluorinated carbon nanofibers at ambient temperature. The friction experiments have been evaluated using a reciprocating ball on a plane tribometer. Moringa oil is used as a bio-additive in lubricant formulations. First, the addition of a small amount of moringa oil to dodecane allowed a reduction of about 50% of the base oil friction performances. Second, a comparative study on the friction properties of their blends with pristine carbon nanofibers (CNFs) and fluorinated ones (CF0.85) was investigated, based on which they were intended to be used as solid lubricant additives. An adsorption effect of fatty acid molecules is observed in CNFs particles unlike CF0.85. Whatever was the percentage of moringa oil added, more promising results were obtained with CF0.85. Physicochemical characterizations of the tribofilms evidence the good antiwear properties of the lubricants.

Moringa and Graphite as Additives to Conventional Petroleum-Based Lubricants

Many researches are focused on the tribological performances of pure vegetable oil in order to replace the conventional mineral engine oils. This work investigates the influence of local moringa oil (noted VO) on the performances of lubricants formed from a blend of dodecane and graphite particles at ambient temperature. In a first part, a reduction of about 50% of friction properties of dodecane is observed when adding small amounts of moringa oil (VO), which is intended to be used as a bio-base performance additive in lubricant formulations. The friction properties of their blends with graphite, generally employed as solid lubricant additive, showed an adsorption effect of fatty acid molecules. The more promising results were obtained for the blend containing 2 w% of VO. Physicochemical characterizations of the tribofilms evidence the good antiwear properties of the lubricant.

Nanoscale viscosity of triboreactive interfaces

It has been long speculated that the good antiwear properties of the nano-thin triboreactive interfaces might have a rheological origin that can greatly influence their friction, lubrication and antiwear characteristics, which account for nearly one quarter of the worldwide total energy consumption. However, the measurement of the nanoscale viscosity of such tribological interfaces is still a challenging task. This is mainly due to their ultralow thickness, i.e. typically < 150 nm, high viscosity and reactivity, which make the currently used bulk, interfacial or micro-gap rheological techniques inadequate. Here we demonstrate two methods, i.e. creep and squeeze flow, that can be used to quantify the viscosity of triboreactive films in-situ as they form and ex-situ after formation. Films generated from the zinc and ashless dialkyldithiophosphate (ZDDP and DDP) antiwear additives were analysed as model systems because of their industrial and academic importance. The results confirm that the formed tribofilms behave as molten glass with an average viscosity ranging from 2 × 1 0 11 to 7 × 1 0 12 Pa s. During its formation, the molten glass showed rich intrinsic rheological properties that allowed them to maintain local order on the nanoscale through the motion and reconfiguration of single and multiple patches within the formed film, which can significantly predetermine its superior antiwear properties. The findings of this study open future opportunities for optimizing the nano-flowable glass to efficiently control the lubrication of tomorrow’s engines without the need of any environmentally harmful oil additives. • Triboreactive films behave as molten glass with rich intrinsic rheological properties. • Local order at the nanoscale predetermines the friction and wear performance. • Nano-flowable glasses are the key to efficient lubrication in tomorrow’s engines. • Single asperity AFM is fully capable of probing the flowability of surfaces nano-patches for energy harvesting and other applications.

Influence of the Organic Moiety on the Tribological Properties of MoS2:Glycol Hybrid Nanoparticles-Based Dispersions

MoS2:glycol hybrid nanoparticles were synthetized through a polyol route. Their tribological properties when used as lubricant additives in a PAO 6 base oil were investigated using a pin-on-disk tribometer. An important friction reduction and good anti-wear performances were observed compared to the base oil and to the no modified particles. The MoS2:glycol nanoparticles were characterized by thermogravimetric analysis, transmission electron microscopy, RAMAN spectroscopy, X-ray diffraction, and Fourier transform infrared. Furthermore, the stability of the dispersion was followed by dynamic light scattering. On the other hand, Field Emission Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, and X-ray Photoelectron Spectrometry analysis showed that the tribofilm formed on the wear surfaces during the friction test is at the origin of the excellent tribological performance of the MoS2 nanoparticles. In particular, it was demonstrated that the interaction of MoS2 with the organic moiety of the nanoparticles plays a key role in the friction reduction and the good anti-wear properties of the dispersions.

Insight into the Effect of TDMs on the Tribological Behaviors of the Ionic Liquid Composite Films.

Ionic liquid (IL) combined with 2D materials has evoked considerable attention in the field of lubrication applications because of their speical structure and outstanding lubrication properties. However, the ambiguous effect of the 2D materials on the friction and anti-wear properties of the IL needs futher study. Here, we have obtained two families of IL composite films with additives of MoS and graphene via a combined process of spin-coated and curing, and the distinction of the effects of two additives on the tribological performance of the IL films was studied. The friction tests showed that the friction coefficient and anti-wear life of the IL films were greatly enhanced after the addition of MoS or graphene, which could be attributed to the improved load-carrying capacity and the second lubrication phase. Under a low addition content, graphene had more advantages to reduce the friction of the films, and MoS was more beneficial to the tribological properties with the additional content increased. The films with low friction and good anti-wear properties may be valuable for the rational design of lubrication films for the practical engineering applications.

NTI-WEAR PROPERTIES OF MEDIUM CARBON STEEL AFTER CARBURIZING WITH SUBSEQUENT DIFFUSION CHROMIZING AND PVD TREATMENT

The paper discusses the results of research on the structure and tribological properties of hybrid layers produced on the surface of medium-carbon steel in hybrid treatment, combining gas carburizing process with the next treatment, i.e. diffusion chromizing and PVD treatment. A comparison was made of the structure and tribological properties of the layers obtained as a result of hybrid treatment with the layers produced in a single diffusion chromizing process. The studies of the layers concerned their structure, chemical composition, thickness, and hardness. Linear wear of the layers were performed by means of three-cylinder-cone method. It has been shown that the linear wear of samples with hybrid layers, produced on medium carbon steel, is less than 50% of samples with single carbide layers. This indicates very good anti-wear properties of hybrid layers.

Tribological Properties of Alkyldiphenylethers in Boundary Lubrication

Lubricants that are used in miniaturized moving mechanical components generally serve under severe conditions, such as high temperature, high speed, and high load. Although alkyldiphenylethers (ADEs) are used as base oils for high-temperature greases, their tribological properties remain unclear. This study investigated the influence of the alkyl chains on the tribological properties of ADEs. Longer and more attached alkyl chains decreased the friction coefficient of ADEs under both reciprocating and continuous sliding conditions. Wear was found to be independent of the alkyl chain under reciprocating sliding conditions due to abrasion being caused by debris that was not readily removed. ADEs showed good anti-wear properties when used as either a lubricant or an additive under continuous sliding conditions. Much smoother surfaces in the friction track were observed in comparison to poly-α-olefin. Fourier-Transform infrared spectroscopy analysis suggested that the ether groups were attracted to the worn steel surface, phenyl groups became consequently perpendicular, and the attached alkyl chains repelled other substances and prevented further wear of the surface. Moreover, ADEs showed a high adaptability with traditional additives.

Integration of MoST and Graphit-iC coatings for the enhancement of tribological and corrosive properties

MoS2-based coatings present low friction coefficients in vacuum or inert environments, but they also present high wear rates in air environments, which is difficult to serve in complicate environments and extreme conditions. It is becoming more important to improve tribological properties in various environments for widely use. Conversely, carbon-based coatings exhibit good anti-wear properties in air environments, especially humid environments. In this study, we introduced the hydrogen-free carbon-chromium coating(Graphit-iC™) into the MoS2 coating doped with titanium(MoST™) by layer-by-layer deposition techniques, and we built a series of MoST/Graphit-iC multilayer coatings with different numbers of layers. The results show that multilayer coatings are composed of denser structure compared with the MoST coating. Furthermore, the tribological performance in various environments are significantly improved by building the multilayer structure. The lowest wear rate and longest wear life in ambient environment are obtained with 8 layers and the friction coefficient decreases to around 0.02 in vacuum environment. In addition, interfaces between MoST layers and Graphit-iC layers can inhibit the permeation of the corrosive mediums. Overall, the improvement of the tribological performance and corrosion resistance are attributed to the heterogeneous interfaces in multilayer coatings, and multilayer coatings exhibit great potential in widely use.

USING OF ESTERS AS DISPERSION MEDIUM OF POLYUREA PLASTIC GREASES

This article presents first results of the investigated physico-chemical and operational parameters of composition greases obtained with the use of esters of different nature as a dispersion medium and the polyurea as a thickening agent, including the addition of nanocellulose. The choice of the ester base for the production of greases is possible due, on the one hand, to good combination of the physico-chemical properties (high viscosity index, low volatility, high flash and ignition temperature, low pour point, good anti-wear properties). On the other hand, in the production of greases with good ecological characteristics biodegradability of its components is of great importance, which in this case is provided by the use of esters as an oil base and an organic thickener, nanocellulose, as a component of the polyurea dispersed phase. It has been shown that from the dicarboxylic acid esters studied, the polyurea greases based on dioctyl adipate are superior to the dropping point and better colloidal stability as compared to dioctyl sebacate and dibutyl sebacate. The smaller size of the ether molecule provides the stronger structure of the polyurea grease. Similarly, for branched ethers, the grease based on tri-basic alcohols is more effective than the four-basic alcohols. The possibility of using nanocellulose as a thickener component was demonstrated. An increase in the content of nanocellulose to 3.5% increases the colloidal stability and the dropping temperature of the synthesized greases. The obtained samples have a wider range of operating temperatures, better rheological indicators than imported and domestic analogues.

Ionic Liquids and its Potential in Lubricants: A Review

Lubricants have been associated with advancement of the human civilization with the changing priorities from “Transportability” in prehistoric times to “Longevity” in the modern times and then lately to “environment friendly”. Ionic liquids (ILs) are the room temperature molten salt and compounds of cations and anions. There are thousands of cations and anions hence millions of unique ILs are possible. The discovery of ILs have opened new frontier of research in many disciplines of science, one of the promising field is energy efficient and eco-friendly lubricants. First article on ILs as neat lubricant was published in year 2001 and till year 2011 ILs were being studied as base (neat) oil. The first oil soluble IL was synthesised in year 2012 and showed good anti-wear and anti-friction properties. This work gives the brief introduction of ILs and some of the recent advancements in developing ILs as additives for lubrication with an attempt to correlate oil-solubility, and lubricating behaviour. ILs are recent additives and still not commercialised in lubricants and its synergy need to be studied along with the other additives. This work will also focus on Influence of IL’s concentration in lubricants and the synergy between ILs and other additives in the synthesis of lubricants. At the end direction for future research has been discussed.

Experimental research for biomass steam gasification in a fluidized bed

ABSTRACTA fluidized bed gasification system was built to investigate the biomass steam gasification performance in different conditions. Medium heating value syngas with 34% H2 content and no more than 20 g/Nm3 tar content could be obtained under 800°C with a S/B (steam vs. biomass ratio) of 0.9 by using olivine as bed material. The results indicated that syngas quality (including H2 content, gasification efficiency, tar reduction, etc.) is in a positive correlation with temperature and S/B, but has a negative correlation with fluidization number (FN). Compared with quartz sand and dolomite, olivine is more suitable for fluidized bed because of its catalytic ability and good abrasion performance for fluidized bed gasifier. As a result, a set of optimum parameters is recommended with S/B of 0.9~1.0, FN of 1.4, and temperature of 800°C in this study.Tar is a by-product from the gasification process, which will cause the pipeline congestion, reduce the gasification efficiency, and deteriorate the working condition. According to this experiment, the temperature and S/B both have a negative effect on tar content, while tar content increased with increase in the FN. Dolomite and olivine both have an inhibition function on tar, and the olivine is considered the best choice of bed material because of its good anti-wear properties.

The Synergistic Antiwear Performances of Organic Titanium Compounds Containing Sulfur with Borate Ester Additive

Two oil-soluble organic titanium compounds (OTCs) such as titanium dialkyldithiocarbamate (TiDDC) and sulfurized titanate (TiS) were synthesized and identified by Fourier-transform infrared spectroscopy (FTIR). The antiwear and extreme pressure properties of TiDDC or TiS with borate ester containing nitrogen (BNO) additive in mineral base oils were evaluated by four ball tester. The results show that TiDDC and TiS not only possess good antiwear and load-carrying properties, respectively, but also exhibit good antiwear synergism with BNO additive without impairing extreme pressure performances. Moreover, the synergistic antiwear properties of the said additives are improved significantly under the optimum additives ratios. The topography of wear scar and the composition and chemical states of typical elements on the rubbing surfaces were analyzed by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) and X-ray photoelectron spectrometer (XPS). The proposed synergistic antiwear mechanism involves an effective interaction between TiDDC or TiS and BNO additive, respectively.

Diamond derivating coating impact on wearing in combustion engine

Piston – ring – cylinder is the typical and simple example of the friction pair that we can find in combustion engine where wearing is one of the main problem. Research on stability of friction pairs are focused on the surface and the top layer of surface in the parts. The main goal is find new solutions in design and materials in order to reduce wearing, which is consistent with the observed trend of technology development. This article presents one of the stages in the research of the newly developed piston ring designed for an internal combustion engine, in which the novelty is an innovative diamond-derivative coating with very good anti-wear properties. Objective of this work was to realize an endurance test in railway engine EMD645 based on rings with diamond coatings and a test of roll-block type on tribotester to set wearing and friction forces of specimen. The super-hard, anti-wear amorphic coatings based on carbon-like diamond show a promising direction in automotive industry, mainly in terms of decreasing friction coefficient in parts of internal combustion engine. The work aims to show the possibilities and benefits of the application of new protective coatings on structural elements.

Enhancement of wear resistance of Ti—6Al—4V alloy by picosecond laser surface micro texturing process

A pulsed, picosecond Nd:YAG laser with a wavelength of 532 nm is used to texture the surface of grade 5 titanium alloy (Ti—6Al—4V) for minimizing its wear rate. The wear properties of the base samples and laser surface textured samples are analyzed by conducting wear tests under a sliding condition using pin-on-disk equipment. The wear tests are conducted based on the Box—Benhken design, and the interaction of the process parameters is analyzed using response surface methodology. The wear analysis is conducted by varying the load, rotating speed of the disc, and track diameter at room temperature with a sliding distance of 1500 m. The results demonstrate that the laser textured surfaces exhibited a lower coefficient of friction and good anti-wear properties as compared with the non-textured surfaces. A regression model is developed for the wear analysis of titanium alloy using the analysis of variance technique. It is also observed from the analysis that the applied load and sliding distance are the parameters that have the greatest effect on the wear behavior followed by the wear track diameter. The optimum operating conditions have been suggested based on the results obtained from the numerical optimization approach.