Enhancement Of Tribological Performance Research Articles

A Comprehensive Review of Cathodic Arc Evaporation Physical Vapour Deposition (CAE-PVD) Coatings for Enhanced Tribological Performance

In the realm of industries focused on tribology, such as the machining industry, among others, the primary objective has been tribological performance enhancement, given its substantial impact on production cost. Amid the variety of tribological enhancement techniques, cathodic arc evaporation physical vapour deposition (CAE-PVD) coatings have emerged as a promising solution offering both tribological performance enhancement and cost-effectiveness. This review article aims to systematically present the subject of CAE-PVD coatings in light of the tribological performance enhancement. It commences with a comprehensive discussion on substrate preparation, emphasizing the significant effect of substrate roughness on the coating properties and the ensuing tribological performance. The literature analysis conducted revealed that optimum tribological performance could be achieved with an average roughness (Ra) of 0.1 µm. Subsequently, the article explores the CAE-PVD process and the coating’s microstructural evolution with emphasis on advances in macroparticles (MPs) formation and reduction. Further discussions are provided on the characterization of the coatings’ microstructural, mechanical, electrochemical and tribological properties. Most importantly, crucial analytical discussions highlighting the impact of deposition parameters namely: arc current, temperature and substrate bias on the coating properties are also provided. The examination of the analyzed literature revealed that the optimum tribological performance can be attained with a 70 to 100 A arc current, a substrate bias ranging from −100 to −200 V and a deposition temperature exceeding 300 °C. The article further explores advancements in coating doping, monolayer and multilayer coating architectures of CAE-PVD coatings. Finally, invaluable recommendations for future exploration by prospective researchers to further enrich the field of study are also provided.

Synergistically assembled RGO/Si3N4 whiskers hybrid aerogels to endow epoxy composites with excellent thermal and tribological performance

Epoxy resin (EP) composites with satisfactory thermal and tribological performance are highly required for engineering moving components. However, the simple addition of fillers leaded to the serious filler agglomeration and limited promotion in tribological properties. In this work, we constructed a new kind of three-dimensional (3D) reduced graphene oxide (RGO)/Si3N4 hybrid aerogel for EP composites, which was prepared by a facile hydrothermal self-assembly method followed by freeze-drying technique. As a result, the dispersibility of Si3N4 whiskers was greatly improved through wrapping of polydopamine—polyethyleneimine copolymer (PDA—PEI) copolymer and physical spacing of 3D skeleton. Furthermore, benefiting from the synergistic effect of RGO and Si3N4@PDA—PEI in the thermal network, the thermal conductivity of RGO/Si3N4 hybrid aerogel (GSiA)—EP increased by 45.4% compared to that of the neat EP. In addition, the friction coefficient and wear rate of GSiA—EP decreased by 83.7% and 35.8%, respectively. This work is significant for opening a tribological performance enhancement strategy though constructing 3D hybrid architecture.

Tribological Performance Enhancement of Bronze Alloy through Microwave Irradiation: Fundamental Tribo-Tests and Real-Time Journal Bearing Applications

Tribological Performance Enhancement of Bronze Alloy through Microwave Irradiation: Fundamental Tribo-Tests and Real-Time Journal Bearing Applications

Enhancement of tribological performance in Li2TiO3/ZrO2 composite coating prepared by industrial hot-dip galvanization process

Hot-dip galvanization is a reliable industrial coating method to tune the surface properties, especially tribology, in an exceptional way. The unique morphological and layered structure of the composite plays a significant role in yielding distinct wear resistance. Lithium titanate (Li2TiO3) has a unique layered structure that can be scientifically used to improve wear resistance in industrial coating systems. In this work, Li2TiO3 has been synthesized using a sol-gel method, and subsequently, a lithium titanate/zirconia (Li2TiO3/ZrO2) composite coating has been prepared by the hot-dip galvanization process. The absence of any other phase in the composite revealed the absence of any possible interaction between the oxides. X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) confirmed the successful incorporation of the composites in the coating. The surface morphology and the surface roughness of the coatings were studied using Field Emission Scanning Electron Microscopy (FESEM) and Optical Surface Profilometry (OSP). The Li2TiO3/ZrO2 composite coating showed a hardness value as high as 3112 HV, high friction coefficient and 10 times higher wear resistance compared with pure Li2TiO3. This low-cost coating technique and the introduction of Li2TiO3/ZrO2 composite in the hot-dip galvanization process constitute a novel approach to finding a possible material for industrial applications.

Significant enhancement of tribological performance of carbon fabric/phenolic composites via interfacial modification and use of a lubricant additive

AbstractImproving the tribological performance of carbon fabric (CF)/polymer composites is vitally significant for developing high‐performance lubricating materials. We propose the combination of interfacial modification and use of a lubricant additive to enhance the antifriction and anti‐wear properties of CF/phenolic (PF) composites. And the tribological properties of CF/PF composites were characterized using ball‐on‐disc friction and wear tester. First, ZnO nanorods were densely and uniformly grown on the carbon fiber surface using POSS as a “bridge molecule” to make fiber with a rough micro‐nano microstructure and active functional groups; this was conducive to enhancing the interlaminar shear strength (ILSS) and wear resistance of CF/PF. Then, graphite (Gr) was further introduced as a lubrication additive into the modified CF‐POSS‐ZnO/PF to increase the friction‐reducing capacity. The corresponding modified composite with 5 wt% Gr demonstrated outstanding tribological performance. The coefficient of friction and wear rate decreased by 55.37% and 93.36%, respectively, compared to those of CF/PF. Moreover, it still retained outstanding friction and wear properties in the sliding process with high loads and speeds. The synergistic mechanism of interfacial modification and lubricant additive on the tribological performance of CF/PF are discussed systematically on the basis of the analysis of the ILSS, fracture surface microstructures, and worn surfaces of the composites. This work might shed new light on the design and development of high antifriction and anti‐wear CF/polymer composites.

Boehmite nanoparticles for potential enhancement of tribological performance of lubricants

A set of nanolubricants was prepared by varying concentrations of Boehmite nanoparticles (0.25,0.5,0.75,1 wt%) in synthetic base oil (PAO-6) with a fixed concentration of dispersant (PIBSA). This is the first study exploring Boehmite mineral for its antiwear and extreme pressure performance. Nanolubricants showed excellent colloidal stability for over 30 days without any sedimentation and improved viscosity index by 4.35% at 1 wt% concentration. Four ball tribometer was used for exploring the tribological performance of Boehmite nanolubricants. A significant 24% wear reduction over base oil was observed for optimum NPs concentration of 0.5 wt% beyond that performance deteriorated. On the other hand, increased NPs concentration enhanced load-bearing capacity for EP test and the highest enhancement of 40% was observed for 0.75 and 1 wt% concentrations. Based on surface characterization techniques, we confirm dehydration of Boehmite NPs into Aluminium oxide (Al2O3) under tribostress. We further confirm regenerative, sacrificial protective tribofilm composed of tribosintered Al2O3 along with oxide film on the rubbing surfaces.

Enhancement of Tribological Performance in Li2tio3/Zro2 Composite Coating Prepared by Industrial Hot-Dip Galvanization Process

Enhancement of Tribological Performance in Li2tio3/Zro2 Composite Coating Prepared by Industrial Hot-Dip Galvanization Process

Fabrication of Interference Textures on Cemented Carbides Using Nanosecond and Femtosecond Laser Pulses

Abstract Laser surface texturing has become popular in recent years, as its application in various fields may result in relevant benefits in different fields, such as tribological performance enhancement of contact surfaces. As frontline engineering materials, cemented carbides are widely used in the mining and manufacturing industries. In the case of cutting tools, surface texturing of working surfaces of cemented carbides emerges then as an interesting option. In this work, line-like structures are produced on the surface of a chosen cemented carbide grade by the method of direct laser interference patterning (DLIP), using nanosecond and femtosecond laser pulses, respectively. Specific laser setups are individually configured to obtain topographic features on the scale of a micrometer. It is aimed to assess the production precision using such configuration and compare the possible ablation effects induced by the two typical laser setups. Topographic features of the produced patterns are characterized using confocal laser scanning microscopy. Morphological features and surface integrity are examined by scanning electron microscopy combined with focused ion beam (FIB) milling. It is found that satisfactory geometrical precision is achieved both nano- and femtosecond lasers. It also complies with theoretical estimations. Surfaces formed by the femtosecond laser are cleaner and show smoother patterns, exhibiting lower melting or microcrack formation.

Enhancement of tribological performance of centrifuge cast functionally graded Cu–10Sn–5Ni alloy with ceramic reinforcements

Functional grade composites Cu–10Sn–5Ni reinforced with 10 wt%SiC and 10 wt%Al2O3, respectively, and their alloy was developed through horizontal centrifuge cast technique. Sample composites and alloy were cast at cylindrical dimensions of Φout100 × Φin70 × 100 mm. They were later subjected to tribology analysis during non-lubricated sliding. Anti-wear performance variations at inner (0–8 mm) and outer (8–15 mm) wall thicknesses of both composites and alloy were experimented using pin-on-disc tribo-tester. Experimentation with increasingly varied parameters like load and slid distance showed a rising trend of wear and friction. This was observed while comparing between the least (10 N, 500 m) and highest (60 N, 3000 m) varied parameter; for both alloy and composites. Also, a proportional decline in coefficient of friction with increase in slid velocity was exhibited for both composites; whereas alloy showed a linear rise. Worn specimen analysis using scanning electron microscopy on both composites revealed Mechanically Mixed Layer formation at both zones. This caused reduction in friction coefficient at high velocity (6 m/s).

Pristine and Alkylated MoS2 Nanosheets for Enhancement of Tribological Performance of Paraffin Grease Under Boundary Lubrication Regime

In the present study, lubricating grease was developed with paraffin oil and 12-lithium hydroxy stearate metal soap as a thickening agent. MoS2 nanosheets were synthesized by hydrothermal method and functionalized with 1-octadecanethiol (i.e., MoS2-ODT). The MoS2 and MoS2-ODT nanosheets were dispersed in the grease with different concentrations to evaluate its tribological performance. Tribological results unveiled that the addition of MoS2 nanosheets in grease appreciably reduced the coefficient of friction and mean wear volume of tribo-interfaces as compared with pure grease. Energy dispersive spectroscopy (EDS) spectrum revealed the deposition of MoS2 on the worn surface and confirmed a thin tribo-film which protects steel tribo-pair against wear.

Fabrication of Hybrid Surface Composites AA6061/(B4C + MoS2) via Friction Stir Processing

Poor tribological properties restrict structural applications of aluminum alloys and surface composites of aluminum alloys have gained more attention in material processing. The addition of solid lubricant reinforcement particles along with abrasive ceramics contributes to the enhancement of tribological performance of surface composites. In the present study, the solid-state technique, friction stir processing (FSP) was used to develop mono (B4C) and hybrid (B4C + MoS2) surface composites in the AA6061-T651 aluminum alloy. The hybrid surface composites were produced by varying an amount of MoS2. Multipass FSP with different direction strategies was adopted for achieving uniform distribution of reinforcement powders in the aluminum matrix. Microstructure analysis showed a uniform dispersal of reinforcement particles without any clustering or agglomeration in the processing zone. Microhardness and wear performance of mono and hybrid composites improved in comparison with the base metal. The mono surface composite exhibited the highest hardness while the hybrid surface composite (75%B4C + 25%MoS2) achieved the highest wear resistance. This was attributed to the solid lubricant nature of MoS2. Furthermore, dissolution of the strengthening precipitate condition during multipass FSP without reinforcement particles resulted in the reduction of hardness and wear resistance.

Dispersion Stability and Lubrication Mechanism of Nanolubricants: A Review

The advent of nanotechnology has resulted in a significant number of experimental studies over the past decades into the use of nanoparticles as lubricant additives (also known as nanolubricants). Nanolubricants offer a solution to the environmental problems associated with traditional lubricant additives that contain sulphur, chlorine and phosphorus. Despite their excellent tribological performance, the poor long-term stability of nanolubricants limits their use in real applications. We herein present a review of recent efforts and progress in the preparation of stable nanolubricants, including the evaluation of nanolubricants dispersion stability, factors that affect dispersion stability, and techniques to enhance stability of nanolubricants. This paper also discusses the effects of dispersion stability of nanolubricants on the tribological performance and lubrication mechanisms involved in the enhancement of tribological performance. Finally, research challenges and possible solutions to this problem are discusses.

Mechanism for improvement of friction/wear by using Al2O3 and SiO2/Gear oil nanolubricants

Gear oil of heavy mining machineries are designed to provide anti-wear and anti-friction protection under extreme load condition. In present study thermophysical and tribological properties of industrial gear oil with nanoparticles additives (Al2O3 and SiO2) has been experimentally evaluated. Morphology of dry nanoparticles under FE-SEM shows that both nanoparticles are spherical. DLS test shows the presence of mild-agglomeration of nanoparticles in the dispersion. Density and viscosity of nanolubricants is tested with varying temperature and particle volume fraction. Measured viscosity results for Al2O3/gear oil nanolubricants follow the existing empirical model and new model has been proposed for SiO2/gear oil nanolubricants. Anti-friction and anti-wear properties of nanolubricants are tested on pin-on-disc test apparatus. FE-SEM and energy dispersive spectroscopy (EDS) analysis of wear scar (pin SS-304), evident the occurrence of ball bearing and surface polishing effects, which may be responsible for advanced tribological properties of the oil. Test results reveals that ball bearing have dominating effect in enhancement of tribological performance.

Enhancing lubricating oil properties using novel quinazolinone derivatives: DFT study and molecular dynamics simulation

Lubricating oils are of a paramount importance for smoothing the movement of automotive engine components and maintaining the overall performance of vehicles. These oils are composed of base oil produced mainly from crude oil in addition to some enhancing additives, among them are antiwear additives and antioxidants. Herein, we report on the synthesis and spectroscopic characterization of four quinazolinone derivatives and their application as antiwear additives and antioxidants. These compounds have been synthesized via microwave-assisted method, differing in certain functional groups, and their structures have been confirmed by elemental analysis and spectroscopic analyses including 1H-NMR and FT-IR. In an attempt to investigate the tribological performance enhancement and the antioxidation effect of these compounds for lubricating oil, DFT-based quantum calculations were run and discussed. In addition, molecular dynamics simulation was performed to model the adsorption orientations of these compounds over Fe (110) surface to explain how their tribological enhancement and antioxidation performance proceed.

Enhancement of mechanical, thermal and tribological properties of AAPS-modified graphene oxide/ polyamide 6 nanocomposites

Abstract Polymer composites exploiting the outstanding properties of graphene have already attracted considerable attention. Amino-modified graphene oxide (AMG) was designed via N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPS) anchoring on the sheets' surfaces, as confirmed by X-ray photoelectron and fourier transform infrared spectroscopy data. It was found that the AMG had good dispersity and higher thermal stability. AMG/PA6 composites with various weight percentages of graphene platelets (0, 0.25, 0.5, 0.75, 1%) were prepared by solution blending and melting mixture. AMG markedly reduced the friction coefficient and increased the wear resistance of the polymer composites. It was shown that the friction coefficient of the AMG/PA6 composite reached 0.237, i.e., 44.6% lower than that of neat PA6, and the wear rate was decreased by 33.2%. The relations of the mechanical, thermal, tribological properties and the microstructure of the AMG/PA6 composites were also discussed. Such enhancement of tribological performance was primarily attributed to the synergistic influence of the mechanical and thermal properties of the composites and the high self-lubricity of AMG.

Investigation of laser texture density and diameter on the tribological behavior of hydrogenated DLC coating with line contact configuration

The technique of laser texturing has been gaining popularity in recent years because of its use in enhancement of tribological performance. In this paper, the effect of indirect laser texturing is analyzed on hydrogenated DLC coating under line contact configuration. Most previous research studies have been carried out for point contact configuration. The aim of this study is to investigate the effectiveness of indirect laser textured DLC for cam/tappet contact in an engine. For this reason, this study focuses on line contact. The tribological performance of textures is dependent on their geometric parameters. Therefore, textures' diameters and densities were varied. The results indicated that at a diameter of 50-μm and 20% density, tribological performance of a cylinder on a coated plate tribo-pair can be enhanced.

Enhancement of tribological performance of epoxy bulk composites and composite coatings using micro/nano fillers: a review

Epoxies in the form of bulk and coatings have been used throughout the years for a wide spectrum of applications in various industries ranging from aerospace, oil and gas, petrochemical and marine to several others. Their use in tribological applications, those involving a range of contact conditions and where the requirement is exceptionally low wear and friction coefficient, is often limited by the properties of the pristine epoxy matrix such as low load bearing capacity combined with low thermal conductivity values. These properties have been improved by the addition of nano-fillers, and numerous studies have been carried out in this regard. This paper presents a detailed review of the works carried out in the recent years where addition of nano-fillers to formulate epoxy-based composites and coatings has shown a substantial improvement in wear and friction properties thereby enhancing their potential to be used in demanding tribological applications such as solid lubricant in bearings, as wear-resistant protective coatings in rotating and stationary equipment and for applications in the construction industry such as floorings and airport runway repairs. Copyright © 2016 John Wiley & Sons, Ltd.

Fabrication, mechanical performance and tribological behaviors of polyacetal-fiber-reinforced metakaolin-based geopolymeric composites

A type of new fiber-reinforced geopolymeric composites was developed by combining metakaolin and polyacetal (POM) fibers. High-strength POM fibers were first prepared through melt spinning followed by a hot-drawing procedure, and then a series of metakaolin-based geopolymeric composites with different contents of POM fibers were synthesized. The mechanical and tribological properties of the resulting composites were evaluated, and the morphology and microstructure were investigated. The POM fibers provided significant mechanical reinforcement for the metakaolin-based geopolymer. The composites were optimized for flexural and compressive strength with respect to fiber content and fiber length. Compared to unreinforced geopolymer, the composites obtained an optimum improvement by approximate 150% in flexural strength and by almost 26% in compressive strength. Moreover, the longer POM fibers exhibit a better reinforcement effect on the geopolymer, resulting in a lower optimal fiber content for the composites to achieve the maximum mechanical data. The reinforcing mechanisms were discussed on the basis of morphological investigation and considered as a cumulative energy-dissipating effect by fiber pullout and orientation, fiber rupture, fiber debonding from the matrix, and fiber bridging within cracks. The geopolymeric composites also achieved a considerable reduction in friction coefficient and abrasion loss rate in the presence of POM fibers. Such an enhancement of tribological performance is ascribed to the formation of self-lubricating transfer films between the contact surfaces of composites against the steel counterpart.

Tribological studies of epoxy and its composite coatings on steel in dry and lubricated sliding

Industrial lubricants are invariably used with additives (with high sulfur and phosphorous contents) for tribological performance enhancement. However, these additives are environmentally very harmful. Hence, there is an urgent need to find alternate solutions for enhancing the tribological performance of lubricants and components without the use of harmful additives. The objective of this work is to investigate the feasibility of using polymer composite coatings in enhancing the tribological properties of steel surfaces in dry and base oil lubricated conditions. Pure epoxy and its composite (with 10 wt-% of graphene or graphite powder) films were coated onto steel substrates and tested under dry and base oil lubricated conditions. Friction and wear experiments were conducted on a ball on cylinder tribometer between polymer/composite coated cylindrical steel surface (shaft) and an uncoated steel ball as the counterface. Tests were conducted at various normal loads and speeds. In dry condition at 3 N load and 0.63 m s− 1 sliding speed, the wear life of epoxy was increased by five times and coefficient of friction was nearly the same (0.18) on inclusion of graphene nanoparticle. In lubricated case, epoxy/graphene composite coating performed eight times and more than five times better than pure epoxy and epoxy/graphite respectively.

Surface Modified UHMWPE Particles by Direct Fluorination Blended with Polyurethane for Enhancing its Wear-Resistant Performance

In this study, Ultra-high molecular weight polyethylene (UHMWPE) particles were surface treated by F2/N2 and F2/O2/N2 two direct fluorination routes. A great number of polar groups are grafted on the surface of UHMWPE particles after direct fluorination confirmed by FT-IR and X-ray photoelectron spectroscopy (XPS) characterization. Two kinds of surface modified UHMWPE particles were blended with thermoplastic polyurethane (TPU) by dissolving in solvent. The scanning electron microscope (SEM) demonstrates that the interfacial interaction degree between the two polymer phases is correlated with the chemical composition of a fluorinated surface layer. The TPU composite with the UHMWPE particle treated by F2/O2/N2 route obtains excellent tribological performance enhancement with significant decrease in wear loss, ranging from 192.9 mm3 to 97.8 mm3, about 49.3% reduction compared with the virgin TPU.