Excellent Lubricating Properties Research Articles

One-pot synthesis of SIB@ZIF-8 with enhanced anti-corrosion properties and excellent lubrication properties

Sulfurized isobutylene (SIB) is widely used for extreme-pressure additive. However, the high sulfur content of SIB may cause excessive metal corrosion. Here, we present a strategy for the one-pot encapsulation of SIB in zeolitic imidazolate framework-8 (ZIF-8). The tribological properties of SIB@ZIF-8 as an oil additive was studied by a ball-on-disk reciprocating tribometer. In comparison to SIB and mechanically mixed SIB/ZIF-8, SIB@ZIF-8 displayed better inhibition of metal pairs corrosion, and exhibited higher anti-wear property and load-carrying capacity. This may be attributed to slow release of SIB from SIB@ZIF-8 during the friction process. This study broadens the tribological application of ZIF-8 and also provides a highly promising extreme-pressure additive for future industrial applications.

Effect of Fatty Acid Methyl Ester on Fuel-Injector Wear Characteristics

This paper presents the experimental results carried out to evaluate the fatty acid methyl ester (FAME) obtained from cotton-seed oil and palm oil on fuel-injector wear characteristics. The cottonseed oil methyl ester (COME) and palm oil methyl ester (POME) were produced in the laboratory using alkaline transesterification. Gas chromatography based on 'BS EN 14103:2011' standard was used to analyze the percentage of fatty acids in COME and POME. The physicochemical properties of the two methyl esters were measured based on ASTM and EN standards. Various unique blends using cottonseed–palm oil methyl ester (CPME) were tested. Thirteen (13) different types of fuel blends were prepared from COME, POME, and petroleum diesel fuel (DF100). The wear and lubricity characteristics were measured using a high-frequency reciprocating rig (HFRR) based on ASTM D6079 standard. The worn surfaces of the specimen plates were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The COME100, POME100, and CPME100 showed excellent lubricity properties for the fuel injector in terms of lower COF and wear coefficient when compared with DF100. COME100, POME100 and CPME100 showed lower average COF compared to DF100 by 16.9%, 13.9% and 16.1%, respectively. This may be due to the presence of unsaturated fatty acids in the methyl esters composition. Consequently, the fatty acid methyl esters can be used to reduce the friction and wear of the fuel injectors due to the improvement in the tribological properties of the fuel.

Biodegradable lubricating mesoporous silica nanoparticles for osteoarthritis therapy

Osteoarthritis is characterized by lubrication failure of the articular cartilage and severe inflammation of the joint capsule. Lubricating mesoporous silica nanoparticles (MSNs) have been developed for the treatment of osteoarthritis based on enhanced lubrication and local drug delivery. However, MSNs are difficult to degrade in vivo in a short time, resulting in potential toxic effect due to bioaccumulation. In this study, biodegradable MSNs (bMSNs) were prepared through an oil-water biphase stratification method, and modified with poly(2-methacryloyloxyethyl phosphocholine) (PMPC) to synthesize lubricating drug-loaded nanoparticles (bMSNs-NH2@PMPC) by photopolymerization. The in vitro degradation test demonstrated that the bMSNs and bMSNs-NH2@PMPC almost degraded within 7 days. The tribiological test showed that the lubrication property of the bMSNs-NH2@PMPC was greatly improved, with a reduction of 50% in the friction coefficient (COF) compared with the bMSNs. It was attributed to hydration lubrication mechanism by which a tenacious hydration layer is formed surrounding the zwitterionic headgroups (N+(CH3)3 and PO4−) in PMPC polyelectrolyte polymer. Additionally, the bMSNs-NH2@PMPC maintained excellent lubrication property under degradation and achieved sustained drug release behavior compared with the bMSNs. In summary, the biodegradable bMSNs-NH2@PMPC developed in this study with the properties of enhanced lubrication and drug delivery may be a promising approach for osteoarthritis therapy.

Water Lubrication of Ni/Al2O3 Composite Coatings Sliding With Si3N4

Abstract Inspired by the excellent water lubrication properties of Al2O3, two methods are used to fabricate Ni/Al2O3 composite coatings for water lubrication. One is the conventional composite electroplating technique (one-step process). The other is depositing the Al2O3 particles layer on a substrate by electrophoresis firstly and then plating of Ni (two-step process). The morphology of surface and cross section, composition, micro-hardness, and bonding strength of the coatings were investigated. The water lubrication properties of the coatings sliding with Si3N4 were tested and compared. The result shows that the electrophoresis combined with electroplating is an efficient way to improve the Al2O3 particles content in the coatings. With the increasing of the particle content, the coating hardness increases while the bonding strength decreases. More importantly, low friction coefficient can only be achieved for Ni/Al2O3 coating with higher particle content. The comprehensive tribo-chemical reactions of Al2O3 and Si3N4 with water could be the dominated reason. The finds evidence the benefits of the ceramic-based composite coating design for water lubrication.

Bactericidal Lubricating Synthetic Materials for Three-Dimensional Additive Assembly with Controlled Mechanical Properties.

3D printable synthetic materials have been developed to realize desired surface and mechanical properties. Lubricating synthetic surfaces have broad technological impacts on many applications including food packaging, microfluidic systems, and biomedical devices. However, combining soft materials with lubricants leads to significant phase separation and swelling phenomena, together with lowered mechanical strength, impeding full utilization of lubricating synthetic surfaces with desired shapes in a highly controllable manner. Here, we report a new platform to create a 3D printable lubricant-polymer composite (3D-LUBRIC) for the seamless fabrication of multidimensional structures with diverse functionalities. The rationally designed lubricant-polymer mixtures including silica aerogel particles not only exhibit suitable rheological properties for direct ink writing without phase separation but also enable the deterministic additive assembly of heterogeneous materials, which have large mismatches of oil permeability, with no distinct shape distortion. While exhibiting excellent lubricating properties for a variety of liquids, 3D-LUBRIC shows tunable mechanical properties with desired functionalities, such as optical transparency, flexibility and stretchability, and anti-icing and antibacterial/bactericidal properties. We employ the proposed platform to fabricate self-cleanable containers and antibacterial/bactericidal medical tubes. Our platform can offer new opportunities for building low-adhesive, multifunctional synthetic materials with customized shapes for diverse applications.

Fretting wear behavior of brass/copper-graphite composites as a contactor material under electrical contact

In this study, copper-graphite composites were prepared by powder sintering. The wear resistance and electrical contact endurance of composites with different copper-graphite ratios were investigated and are discussed. The results illuminate that the high electrical contact resistance evolution during fretting wear is related to the graphite content. With a decrease in the copper content, the interaction between graphite and copper increases, and the conductivity decreases. The graphite particles of the flat sample delaminate and form a graphite friction film between the contact surfaces; this friction film has excellent lubricating properties. Thus, the copper-graphite composites with the highest graphite content herein demonstrate good behavior against fretting wear and exhibit poor electrical contact performance. In other words, a relatively high copper content could maintain a decreased and stable contact resistance. The comprehensive performance of composite materials can be effectively developed by designing the copper-graphite ratio.

Study on the Development of Banana Fibre Reinforced Polymer Composites for Industrial and Tribological Applications: A Review

Fibres form one of the basic tenets of the human society. Fibres are used as the building block of human existence and thrive. The fibre technology is mostly comprised of artificial fibres in the present day due to their longevity, stability and inertness. However, these fibres destroy the integrity of nature as they are non biodegradable and pollutant in nature. This has led to an increase in the usage of natural fibre based composites. These composites add to the effectiveness of the artificial composites. One such fibre is banana fibre. Banana fibre is obtained from the trunk of the banana tree (Musa acuminata) which is a plant native to Southeast Asia. Effectively considered as a waste material after the harvest of the fruit, banana fibre has shown remarkable properties as an additive in the preexisting fibres. The addition of banana fibres in the materials have shown to produce a remarkable improvement in the chemical, mechanical and physical attributes of the fibres. This paper gives the overall view in the field of banana fibre reinforced polymer composites and its physical, mechanical and tribological properties of the composites. Emphasis is laid in evaluating all the factors of the advantage of banana fibre. Banana fibre reinforced composites, in turn, enable the development of industrial and tribological components having excellent wear, friction and lubrication properties which finds numerous applications

Tribological properties of polyimide-graphene composite coatings at elevated temperatures

This paper focuses on developing a polyamic acid (PAA) of polyimide (PI) and PI filled with graphene (PI/GP) on 100CR6 ESU hardened steel. The tribological testing result of the pure PI and PI/GP against 100Cr6 steel ball at room temperature (RT) and elevated temperatures (50 °C, 100 °C, 150 °C, 200 °C) exhibits that the addition of GP clearly enhances the friction reduction and wear-resistant properties of PI, due to the excellent lubricating properties of GP. The 3 wt % of GP content in the PI is the optimum loading for the lowest friction and wear at RT and elevated temperatures. The SEM analysis of the worn surfaces showed that the high wear-resistant of the PI/GP composite is due to the generation of the loose particles from the coating surfaces which could be embedded on the friction pairs and rolled over there as a lubrication film. Also, at 60 % weight residue the PI/3 G P showed the high decomposition temperature.

Mechanical properties and friction−wear characteristics of VN/Ag multilayer coatings with heterogeneous and transition interfaces

Abstract The heterogeneous multilayer interface of VN/Ag coatings and transition multilayer interface of VN/Ag coatings were prepared on Inconel 781 and Si(100), and the microstructures, mechanical and tribological properties were investigated from 25 to 700 °C. The results showed that the surface roughness and average grain size of VN/Ag coatings with transition multilayer interface are obviously larger than those of VN/Ag coatings with heterogeneous multilayer interface. The coatings with transition multilayer interface have higher adhesion force and hardness than the coatings with heterogeneous multilayer interface, and both coatings can effectively restrict the initiation and propagation of microcracks. Both coatings have excellent self-adaptive lubricating properties with a decrease of friction coefficient as the temperature increases, but their wear rates reveal a drastic increase. The phase composition of the worn area of both coatings was investigated, which indicates that a smooth Ag, Magneli phase (V2O5) and bimetallic oxides (Ag3VO4 and AgVO3) can be responsible to the excellent lubricity of both coatings. To sum up, the coatings with transition multilayer interface have excellent adaptive lubricating properties and can properly control the diffusion rate and release rate of the lubricating phase, indicating that they have great potential in solving the problem of friction and wear of mechanical parts.

Tribological assessment of vegetable oil based CeO2/CuO hybrid nano-lubricant

Vegetable oil based lubricants attract much attention nowadays due to their excellent boundary lubrication performance and biodegradability. Coconut oil is a vegetable oil with excellent lubricating properties which provides low friction coefficient and better oxidation stability. The purpose of this study is to investigate the performance of coconut oil based new hybrid CeO2/CuO nano-lubricant with various ratios of CeO2/CuO viz. 25/75, 50/50, and 75/25 at different concentrations (0.1, 0.25, 0.5, and 1.0 wt%). The rheological, thermal, thermo-gravimetric, and tribological evaluations were conducted for hybrid nano-lubricants and the results were compared with those of base oil (coconut oil) and nano-lubricants containing CeO2 and CuO nano-particles individually. A reduction of 15.7% in average friction coefficient and 23.4% in wear scar diameter was observed with the use of 0.25 wt% CeO2/CuO: 50/50 hybrid. Oil degradation studies and worn surface analyses after engine test were also done. The results showed that the surface enhancement is evidenced with the use of hybrid nano-lubricant.

Ultrastable Lubricating Properties of Robust Self-Repairing Tribofilms Enabled by in Situ-Assembled Polydopamine Nanoparticles.

Aqueous lubrication in nature is attracting increasing attention in the tribological fields for reducing friction energy consumption and improving anti-wear durability. Generally, adding nanolubricant additives is one of the most important strategies to effectively enhance the interface performance under boundary lubrication via the formation of a protective tribofilm on rubbing surfaces. However, the adsorbed tribofilms are unstable and are prone to failure during friction, and the interaction mechanism between the tribofilms and frictional interfaces is partly disclosed. In this study, inspired by mussels, an in situ-assembled polydopamine (PDA) tribofilm is achieved with PDA nanoparticles as aqueous lubricant additives, which shows excellent lubrication properties. The coefficient of friction is interface-independent and is reduced by as much as 83%. The results show that the PDA tribofilm can not only form chemical bonding with metal interfaces but also present a synergistic lubrication effect with the upper ceramic surface. Especially, a self-repairing effect of the PAD tribofilm is observed, by which the ultrastable lubricating properties can be achieved during friction, and thus, the friction and wear can be effectively controlled. This work provides an effective method for improving the interface stability of friction pairs under aqueous lubrication and also shows great meaning for industrial applications.

Laboratory optimization on performance of high density brine-based drilling fluid

The brine-based drilling fluid is paramount for drilling operation in the salt-anhydrite formations. In this work, a novel high density brine-based drilling fluid was designed and established, based on the features of salt-anhydrite formation in Missan Oilfields. A suite of laboratory tests has been carried out to comparatively evaluate effect of key additive amounts on standard properties of drilling fluids. The formula of the high density brine-based drilling fluid was optimized. The newly developed brine-based drilling fluid possesses excellent rheology, filtrate, thermal stabilization, inhibition and lubricity properties, which can provide an alternative to drilling through the salt-anhydrite formation in Missan Oilfields.

Effect of Gradient Nanostructure on Plasma Sulfonitrocarburizing of 42MnCr52 Steel

A nanocrystalline layer was fabricated on the surface of 42MnCr52 steel by ultrasonic surface rolling processing (USRP). Plasma sulfonitrocarburizing (PSNC) was performed on the untreated surface and nanostructure surface to obtain a composite layer composed of the solid lubrication layer (FeS) and nitrocarburized subsurface layer. The effect of the nanocrystalline layer on PSNC was investigated using phase analysis, microstructural analysis, element analysis, hardness analysis, and wear property analysis. The results are as follows: The average grain size of the gradient nanostructure surface was about 40 nm. A more compact and homogeneous sulfide composite layer was formed on the surface of the USRP + PSNC specimen, and the sulfide composite layer was mainly composed of an FeS phase with excellent solid lubrication properties. The thickness of the nitrocarburized layer was increased by 130% on average and its homogeneity also improved after USRP. The hardness value of the subsurface (nitrocarburized layer) of the USRP + PSNC specimen was higher than that of the PSNC specimen. The wear volume and frictional coefficient of the USRP + PSNC specimen were obviously lower than those of the PSNC specimen. The USRP + PSNC specimen exhibited strong wear resistance.

The ecotoxicity and tribological properties of choline monocarboxylate ionic liquid lubricants

AbstractIn this work, a series choline monocarboxylate ionic liquids ([Ch][MA] ILs) were synthesized. The physicochemical properties and lubricating efficiency of the ILs on copper and aluminum discs were systematically investigated. At the same time, their ecotoxicity was explored on aquatic organisms. In comparison with 1‐butyl‐3‐methyl imidazolium tetrafluoroborate (L‐B104), which is a kind of traditional IL, [Ch][MA] ILs exhibited excellent lubricating properties and low toxicities, thus can be considered as environmentally friendly lubricants in tribology.

Crystal structure and tribological properties of molybdenum disulfide films prepared by magnetron sputtering technology

Molybdenum disulfide (MoS2) is widely used in practice due to its excellent lubricating properties. However, research on the tribological properties of magnetron sputtering for depositing MoS2 films remains limited. Herein, the tribological properties of MoS2 films were investigated in detail through a series of characterization and friction coefficient tests. MoS2 films were deposited onto silicon substrates by magnetron sputtering under different radio-frequency powers (Prf). With increased Prf, the crystallinity of the films gradually increases, whereas the friction coefficient initially decreases and then increases. Prf also affects the chemical composition, surface morphology, and grain size of MoS2 films. At Prf = 300 W, the film surface is dense and smooth, the grain distribution is uniform. Moreover, the films have superior tribological properties and low friction coefficient, which can be attributed to the weak van der Waals force among MoS2 layers and the microscopic morphology of the films. All these results indicate that by reasonably controlling the preparation parameters, MoS2 films with excellent tribological properties can be prepared by magnetron sputtering.

Effects of femtosecond laser texture on the tribological properties of 20CrNiMo/beryllium bronze tribo-pairs of rock bit sliding bearings under non-Newtonian lubrication

In this paper, the tribological characteristics of the unit tribo-pairs of rock bit sliding bearings under various loads and high temperatures were investigated. The conical textures, distributed in beryllium bronze surfaces with depth–diameter ratios ranging from 0.087 to 0.483, were fabricated using femtosecond laser irradiation. The friction characteristics of the 20CrNiMo/beryllium bronze tribo-pairs were tested at a high temperature of 120 ℃ and under non-Newtonian lubrication conditions using pin-on-disc configurations. The textured surfaces with depth–diameter ratios of 0.165 and 0.483 exhibited excellent lubrication and wear-resistant properties. In addition, the effects of the operating conditions on the tribological performance of the tribo-pairs were discussed.

Influence of wear parameters on friction performance of A356 aluminum – graphite/ granite particles reinforced metal matrix hybrid composites

In this work aluminium-silicon alloy (A356) is strengthened with blends of granite and graphite particles using stir casting technique. Granite particulates, an industrial waste generated while cutting granite stones is used along with graphite particulates which has excellent lubricant properties. The reinforcements are mixed in different weight proportions, to base alloy at 2 and 4 weight percentages. Wear rate and friction for the fabricated composites and alloy is recorded during each sliding test The dry sliding wear of the over different loads with a track diameter of 60 mm and sliding times of 15, 30 and 45 minutes respectively. The techniques of ANOVA and Taguchi are used to study the influence of wear parameters on the friction coefficient of composites by using “MINITAB 18” software with quality characteristics chosen as smaller is better.

Tribological Properties of Multi-Walled Carbon Nanotube-Cr and Graphene Oxide-Cr Composite Coating

Chromium (Cr)-based coatings have been widely used to strengthen the friction reduction and wear resistance on various kinds of surface. Here, the stable aqueous dispersion of oxidized multi-walled carbon nanotube (MWCNT) and graphene oxide nanosheets (GOS) was obtained by ultrasonic oxidation treatment. Then, MWCNT-Cr and GOS-Cr composite coatings were prepared using the direct current electrochemical co-deposition process on 420 stainless steel in the electrolyte with the addition of MWCNT and GOS under different current density and temperature. The morphology, structure, hardness and tribological properties of MWCNT-Cr and GOS-Cr composite coating are comparatively studied using pure Cr coating as a baseline. The friction reduction performance of MWCNT-Cr and GOS-Cr composite coatings was improved at optimum current density and temperature. The anti-wear properties of MWCNT-Cr and GOS-Cr composite coatings were enhanced by uniform embedment of MWCNT and GOS in coatings increasing the hardness and lubricity. This study suggests that the introduction of oxidized MWCNT and GOS with good dispersion could enhance the wear resistance and friction reduction of pure Cr coating due to their excellent dispersion, mechanical, and lubricant properties.

Tribological Properties of Typical Zeolitic Imidazolate Frameworks as Grease-Based Lubricant Additives

In this study, three different zeolitic imidazolate framework (ZIF) materials of ZIF-8, ZIF-71, and MAF-6 were synthesized, and their tribological properties as base grease were evaluated. We demonstrate that the tribological properties of ZIFs are correlated with the framework density/pore volume and the substituted groups. Under 200 N, MAF-6 has the lowest wear volume value and ZIF-71 exhibits the lowest friction coefficient. As the load increased, MAF-6 maintained the best and most stable tribological performances among the three ZIFs additives; however, the properties of ZIF-71 worsened. Thus, MAF-6 exhibits the lowest density and largest solvent-accessible volume (SAV) and has the lowest elastic stiffness; it easily slides and adheres onto the wear surface, forming a tribofilm that reduces friction and prevents severe wear. ZIF-71 with chlorinated groups may enhance the tribological performance; as the load rises, its dense and stiff structure has an adverse effect. These results are expected to be helpful for designing future ZIFs with excellent lubrication properties.

Fabrication of Novel CeO2/GO/CNTs Ternary Nanocomposites with Enhanced Tribological Performance

Increasing demands of multi-functional lubricant materials with well distributed nanoparticles has been generated in the field of oil lubrication. In this study, one-dimensional (1-D) acidified multi-walled carbon nanotubes (CNTs) and two-dimensional (2-D) graphene oxide (GO) sheets were dispersed together under an ultra-sonication condition to form CNTs/GO hybrids and the corresponding CNTs/GO hybrids decorated with uniform zero-dimensional (0-D) cerium oxide (CeO2) nanoparticles were prepared via a facile hydrothermal method. The tribological performance of CeO2/CNTs/GO ternary nanocomposite was systematically investigated using a MS-T3000 ball-on-disk tester. The results demonstrated that CeO2/GO/CNTs nanocomposites can effectively reduce the friction of sliding pairs in paraffin oil. Moreover, the oil with 1 wt% of CeO2/GO/CNTs exhibited the best lubrication properties with the lowest friction coefficient and wear scar diameters (WSD) compared with adding only GO nanosheet, CeO2, and CeO2/CNTs hybrid nanocomposite as lubricant additives. It is concluded that due to the synergistic effect of 0D CeO2, 1D CNTs, and 2D GO during sliding process, a dimensionally mixed CeO2/GO/CNTs nanocomposite exhibits excellent lubricating properties, providing innovative and effective additives for application in the field of lubrication.