Decrease In Wear Rate Research Articles

Achieving precise graphenization of diamond coatings below the interfacial thermal stress threshold

Abstract Diamond coatings possess numerous excellent properties, making them desirable materials for high-performance surface applications. However, without a revolutionary surface modification method, the surface roughness and friction behavior of diamond coatings can impede their ability to meet the demanding requirements of advanced engineering surfaces. This study proposed the thermal stress control at coating interfaces and demonstrated a novel process of precise graphenization on conventional diamond coatings surface through laser induction and mechanical cleavage, without causing damage to the metal substrate. Through experiments and simulations, the influence mechanism of surface graphitization and interfacial thermal stress was elucidated, ultimately enabling rapid conversion of the diamond coating surface to graphene while controlling the coating's thickness and roughness. Compared to the original diamond coatings, the obtained surfaces exhibited a 63–72% reduction in friction coefficients, all of which were below 0.1, with a minimum of 0.06, and a 59–67% decrease in specific wear rates. Moreover, adhesive wear in the friction counterpart was significantly inhibited, resulting in a reduction in wear by 49–83%. This demonstrated a significant improvement in lubrication and inhibition of mechanochemical wear properties. This study provides an effective and cost-efficient avenue to overcome the application bottleneck of engineered diamond surfaces, with the potential to significantly enhance the performance and expand the application range of diamond-coated components.

Enhancing mechanical properties of 2024-Aluminium Alloy Matrix Composite strengthened by Y2O3 ceramic particles

The development of high-strength, low-weight composite materials has been a high-priority demand in the structural, aerospace, automotive, renewable energy, and sports equipment sectors. Micro-particle size Yttrium oxide (Y2O3) has been utilized to enhance the microstructure and mechanical characteristics of the 2024-Al alloy. The stir-casting technique is employed to prepare 2024-Al alloy and aluminum matrix composites (AMCs) with different Y2O3 weight fractions (1 %, 2 %, and 3 %). Scanning electron microscope ESM with EDS analysis and optical microscope imaging have been used to assess the development in the microstructure of AMCs. Furthermore, optical microscope images have been analyzed by using image processing software, ImageJ to evaluate development in microstructure grain size. Vickers' micro-hardness, tensile strength, elongation, and wear-resistant tests were conducted to assess the mechanical properties of AMCs. AMC image analysis results demonstrated a significant reduction in microstructure grain size. The highest reduction in grain size was recorded when adding 2 wt. % of Y2O3, which was approximately 22.5 % smaller than that of the plain alloy. Other mechanical test results demonstrated an increase in the hardness and tensile strength of AMCs compared with the plain alloy by approximately 58 % and 116 %, respectively, upon the addition of 2 wt. % of Y2O3, also tensile test shows increasing of AMCs elongation at failure point with increasing Y2O3 content, 132 % upon adding 3 wt. %. Finally, wear tests show a decrease in the AMC wear rate with an increasing Y2O3 weight fraction compared to the plain alloy.

Enhancing the Wear Performance of 316L Stainless Steel with Nb2O5 Coatings Deposited via DC Sputtering at Room Temperature under Varied Environmental Conditions

Niobium-based oxides have garnered increased attention in recent years for their remarkable enhancement of corrosion resistance, as well as biofunctional properties of various metallic materials, including 316L SS. However, the mechanical properties of these promising coatings have not been fully elucidated. This study investigated how much the environmental conditions (air, artificial saliva, and NaCl solution) impact the wear performance of 316L SS without and with Nb2O5 coatings deposited via the reactive sputtering technique. The results exhibited a notable decrease in friction coefficient (55% in air, 18% in artificial saliva, 10% in 0.9 wt% NaCl solution), wear area (46% in air, 36% in AS, 17.5% in 0.9 wt% NaCl solution), and wear rate (44.0% in air, 19.5% in AS, 12.0% in 0.9 wt% NaCl solution). Ultimately, the results obtained in the present study elucidate the synergistic mechanisms of corrosion and wear in 316L SS containing Nb2O5 coatings, highlighting its significant potential for applications in the biomedical sector.

Microstructure and Wear Resistance of FeCrV15 Coatings by Laser Cladding

Improving the surface performance and service life of 60Si2Mn steel is an important issue in agricultural machinery. A FeCrV15 coating layer may exhibit excellent performance in wear resistance. This research focuses on studying the microstructure and wear resistance of the FeCrV15 coating layer at various scanning speeds through laser cladding. Microstructure, phase distribution, surface hardness, and wear resistance of the coating layers are analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), a microhardness tester, and laser confocal microscopy. The results indicate that the FeCrV15 alloy coating consists of γ-Fe, V8C7, and Cr7C3. The microhardness of the FeCrV15 coatings increases with the increase in the scanning speed. At a scanning speed of 8 mm/s, the highest microhardness reaches 727.5 ± 27 HV, approximately 2.5 times higher than the substrate. The friction and wear test of the coating is conducted using a 4 mm diameter Si3N4 ball grinding pair. The coatings prepared at different scanning speeds exhibit lower average coefficients of friction and wear rates compared to the substrate. Both the average coefficient of friction and wear rate decrease with increasing scanning speed. At a scanning speed of 8 mm/s, the lowest average coefficient of friction and the lowest wear rate were observed. The main wear mechanisms of the coating are oxidative wear and adhesive wear, with a small amount of abrasive wear.

Carbon fiber/nano SiO2 reinforced polyelectrolyte-graft UHMWPE for water lubricated superlubricity

In this study, a new kind of UHMWPE composite with ultralow coefficient of friction (COF) and high mechanical properties was developed. An efficient method was established to graft hydrophilic monomer 3-sulfopropyl methacrylate potassium salt (SPMK) onto UHMWPE powder by thermal initiation radical polymerization. The COF of UHMWPE grafted SPMK sample was significantly reduced by 50 %. After filling carbon fiber and nano SiO2, the COF of UHMWPE composites can be reduced as low as 0.009 at 0.1 m/s. Besides, a 76.1 % decrease in wear rate of single UHMWPE was achieved. The outstanding tribological properties of UHMWPE composite was attributed to the synergistic effect of hydration lubrication and particle reinforcement. The prepared UHMWPE composite has great potential to realize water lubricated bearing.

Enhancing wear resistance of aluminum 6061 composites with fly ash: A sustainable approach for industrial applications

This study investigated the benefits of adding fly ash as a reinforcement material. The benefits included cost-effectiveness, improved quality, isotropic behavior, and environmental advantages. To improve self-lubrication and wettability behavior, Al6061 alloy composites were fabricated with different amounts of fly ash (0%, 2%, 4%, 6%, and 8% by weight), along with a fixed amount of graphite (3wt.%) and magnesium (2wt.%). Wear tests were conducted using Taguchi’s Design of Experiment (DoE) approach on the composites. The optimized composition with 6% fly ash exhibited the least wear rate under the test conditions of load = 10 N, sliding velocity = 3 m/s, and sliding distance = 2 km. SEM images revealed a uniform distribution of fly ash and graphite reinforcement in the matrix, contributing to enhanced wear resistance. The composites exhibited fewer scratches and plastically deformed surfaces, indicating a decrease in wear rate and increased wear resistance with higher fly ash content. ANOVA were used, and four parameters were identified to be critical, Composition at 34%, Sliding Distance at 27%, load at 23%, and Sliding Velocity at 12% contribution with a statistical confidence of 95%. This research contributes to developing cost-effective and environmentally sustainable materials with improved mechanical properties. It makes them suitable for various industrial applications, such as the automotive industry, where wear resistance is essential.

Friction Coefficient Evolution of Si3N4 Binary Coating with a Stoichiometric Ratio of 57/43

Friction coefficient depends on various factors or surface characteristics during tribological testing, and this friction coefficient can be modified by altering the properties of one of the two contacting surfaces. It is crucial to monitor the friction coefficient continuously, not only at the conclusion of the test. This research examined the evolution of friction coefficient of silicon nitride (Si3N4) coating and H13 steel over different sliding distances (250, 500, 750, 1000 m). The study assessed surface wear and oxidation through three-dimensional profilometry and SEM/EDX. The findings indicated a reduction in friction coefficient by 22%, a decrease in wear rate by 88%, and a reduction in wear volume by 87% when comparing the silicon nitride coated steel to the uncoated steel. Furthermore, the changes in friction coefficient provided insights into the timing of the complete fracture of the hard coating.Graphical abstract

Tribological behavior of the carbon fiber-reinforced epoxy resin matrix composite with orderly arranged carbon nanotubes

In order to improve the wear resistance of carbon fiber (CF)-reinforced epoxy (EP) matrix composite (CF/EP), this study incorporated carbon nanotubes (CNTs) into the CF/EP composite through the chemical grafting method (C-CNTs/CF/EP). The results showed that the orderly arranged CNTs facilitated the stress transfer from the EP matrix to CF, resulting in a 51.60 % increase in tensile modulus, a 31.21 % increase in strength, a 1.25-Shore increase in hardness, a 4.43 % decrease in coefficient of friction, and a 34.44 % decrease in wear rate of the CF/EP composite. In addition, under different friction conditions, including time, load, and reciprocating frequency, the variations in the characteristics and wear forms of the friction surface dominated the changes in the tribological behavior of the C-CNTs/CF/EP composite.

Tailoring the additional content of short carbon fiber in the reduced graphene oxide-Cu self-lubricating composites for enhanced mechanical and tribological performance

The reduced graphene oxide-Cu self-lubricating composites with short carbon fiber fillers were fabricated by powders wet-mixing combined with hot-pressed sintering process. The impacts of short carbon fiber content on microstructure, mechanical and tribological performance of reduced graphene oxide-Cu composites were characterized. The reduced graphene oxide/carbon fiber hybrid fillers were randomly distributed in the sintered bulk compacts. The hybrid filled composites achieved enhancement in mechanical and tribological properties. With increasing carbon fiber content, hardness and compressive yield strength of the prepared composites were increased, and both friction coefficient and wear rate showed a constant decrease trend under different loads. Owing to the synergy effect of reduced graphene oxide/carbon fiber hybrid lubricant fillers during sliding together with the greatly enhanced hardness and yield strength, up to 0.6 wt% carbon fiber incorporation resulted a lowest friction coefficient and decreased wear rate. Randomly distributed reduced graphene oxide/carbon fiber hybrid fillers provided the lubrication to reduce friction and wear for Cu matrix.

Effects of liquid lubricants on the surface characteristics of 3D-printed polylactic acid

In this study, 3D-printed Polylactic acid (PLA) specimens were manufactured and polished using various lubricants to assess their surface, friction, and wear characteristics. After polishing, the surface roughness decreased by approximately 80% compared with that before polishing, except when acetone was used as the lubricant. In particular, under deionized (DI) water and acetone lubrication conditions, the friction coefficient decreased by 63% and 70%, respectively, whereas the specific wear rate decreased by 88% and 83%, respectively, compared with the unpolished specimens. In the case of dry polishing, adhesion, friction, and wear increase owing to surface damage. Ethanol and IPA polishing resulted in hydrolysis and increased friction, but slightly decreased wear rates. The surface of the specimen polished with acetone dissolved and became very rough. Only the surface polished with DI water exhibited hydrophobic properties. When acetone and DI water were used as lubricants, the surface adhesion force, adhesion energy, friction coefficient, and wear rate were lowest. The finite element analysis results showed that the polished surface exhibited stable contact pressure and friction force, while the unpolished surface showed large fluctuations in contact pressure and friction force owing to the laminated pattern. These results suggest that the polishing process is crucial for improving the surface characteristics and mechanical performance of 3D-printed PLA parts.

Positive changes in the mechanical and optical properties of the floor epoxy reinforced with green graphene

AbstractSilica‐rich Green Graphene® (GG) derived from agricultural residue is incorporated into a floor epoxy (FEP) matrix. The inclusion of GG particles within the FEP matrix has demonstrated a significant positive impact, resulting in improved optical and mechanical properties and increased durability of the floor coatings. The addition of GG into the original FEP reduces surface pores, with the glazier appearance of the composite coating attributed to a smooth surface enhancing light reflection. It is noteworthy that the FEP exhibits a high coefficient of friction (CoF), thereby constraining its potential in tribo‐logical applications. Nano‐indentation and tribo‐logical tests confirm that, incorporation of the 0.5 wt% GG in the FEP matrix results in a 130.15% improvement in hardness, a 10.45% decrease of nano‐scratch depth, a 34.55% decrease in wear rate, and a 33.33% decrease in CoF w.r.t pristine FEP sample. Tensile testing reveals a significant 37% enhancement in fracture strain, along with improvements of 12.3% in specific flexural strength and 43% in energy absorption. The utilization of GG derived from green processes, such as pyrolysis of residual agro‐biomass, presents an environmentally conscious alternative to conventional polluting as well as nonrenewable materials employed in epoxy‐based floor coatings.Highlights Green graphene/floor epoxy (GG/FEP) composites present a glazier appearance attributed to a smooth surface enhancing light reflection. GG particles enhance the hardness and tribo‐logical performance of the composite. GG/FEP composites show a synergistic enhancement in flexural strength. GG presents a sustainable and economically viable material for the epoxy‐based flooring industry.

Elevated temperature wear and friction performance of WC-CoCr/Mo and WC-Co/NiCr/Mo coated Ti-6Al-4V alloy

The effect of adding Mo to WC-based coatings on the microstructure and dry sliding wear performance at elevated temperatures is investigated. The WC-based coatings are deposited using a high-velocity oxy-fuel process on the titanium-31 substrate. The coating was characterized by microstructure, microhardness, porosity, surface roughness, density, and bond strength. The wear and friction behavior of coatings was evaluated using a ball-on disc tribometer at temperatures of 200, 400, 600, and 800 °C and loads of 20 and 30 N. SEM-EDS and an optical profilometer were utilized to evaluate the wear rate and mechanism. The microhardness and bond strength of WC-CoCr/10%Mo coating is more than that of WC-Co/20%NiCr/10%Mo coatings. The WC-CoCr, WC-CoCr/10%Mo, and WC-Co/20%NiCr/10%Mo coatings exhibited decreasing wear rates up to 600 °C, transitioning to an increase at 800 °C. The oxide phases of CoWO4, WO3, MoO3, CoMoO4, and NiMoO4, formed at 600 °C, aid in reducing the rate of wear and friction coefficient. However, the wear rate slightly increased at 800 °C due to vigorous oxidation and softness of coatings. The friction coefficient of WC-CoCr, WC-CoCr/10%Mo, and WC-Co/20%NiCr/10%Mo coating decreases with increasing temperatures due to the lubricating properties of oxide phases on the worn surface. The WC-CoCr/10%Mo coating demonstrates a lower friction and wear rate than the WC-CoCr and WC-Co/20%NiCr/10%Mo coating. At 200 °C, the predominant wear mechanisms were abrasive and fatigue wear, while at 800 °C, oxidative wear, abrasive wear, and adhesive wear were observed.

Molecular dynamics study on tribological properties of AlCrFeCoNi HEA at different temperatures

The microscopically wear mechanism of AlCrFeCoNi HEA effected by high temperatures still remains unclear. In this work, the tribological properties of AlCrFeCoNi HEA and tungsten carbide (WC) at temperatures ranging from 250, 400, 550, 700, 850 °C was investigated using molecular dynamics methods. Additionally, the shear strain, contact stress, and energy change at different temperatures were analyzed to explore the atomic wear mechanism. The simulated results indicated that the coefficient of friction and wear rate decrease with the increasing temperature, since the dislocation types decrease and the kinetic energy and total system energy increase. And high temperature can inhibit the synergistic effect of strain accumulation and atomic wear on the surface of AlCrFeCoNi HEAs.

Sliding wear-induced compositional lamination in a VCoNi alloy at elevated temperatures, and its implications for reduced friction and wear

During tribological loading of metallic alloys at elevated temperatures, the thermo-mechanical coupling effect can lead to the development of a distinct tribolayer, profoundly influencing their tribological behavior. This study reports on the compositional lamination in the tribolayer during dry sliding wear of a VCoNi multi-principal element alloy at elevated temperatures. As the temperature increases from 25 °C to 600 °C, the alloy exhibits a remarkable 40% reduction in the coefficient of friction and a notable two-order-of-magnitude decrease in wear rate. The compositional lamination at 600 °C reveals a distinct tribolayer comprising a nanocrystalline-amorphous oxide glaze layer, a Ni-rich dealloyed layer, and a plastic deformation layer. Within the oxide glaze layer, three sublayers are identified, each featuring a nanocrystalline-amorphous nanocomposite structure with unique equiaxed nanograins. Specifically, the outermost sublayer comprises Co3O4, the intermediate sublayer contains a mixture of Co3O4 and Ni2V2O7, and the inner sublayer consists of V2O5. This multilayered structure is attributed to significant differences in the chemical affinity for oxygen among the constituent elements and their respective diffusion rates in the oxide scale. Significantly, the tribolayer formed at 600 °C exhibits a remarkable 70% increase in yield strength compared to its formation at 25 °C, correlating with a substantial reduction in wear. These findings present a novel avenue for designing self-adaptive, high-temperature wear-resistant alloys through the in-situ formation of a protective compositionally-laminated tribolayer.

Nanosecond laser-assisted fabrication of Ti6Al4V surfaces with gradient wettability and robust cross-linked microstructures

Abstract Surfaces with gradient wettability outperform singular superhydrophobic surfaces in terms of self-cleaning efficiency, anti-contamination properties, and fluid manipulation. These attributes offer extensive application potential across various industrial and scientific domains. This study introduces and employs nanosecond pulsed laser ablation to create wettability gradient surfaces on Ti6Al4V alloys, featuring robust cross-linked frame microstructures. Experimental results demonstrate that by varying the ridge width (w), associated with the liquid-solid contact fraction, we can achieve varying wettability and mechanical durability in these cross-linked frame microstructures. Wettability tests indicate static contact angles ranging from 150.7° to 105.45°. Furthermore, the sandpaper linear abrasion test illustrates a decrease in material wear rate with an increase in w. Under similar test conditions, the proposed surfaces demonstrate superior mechanical durability compared to two other prevalent wettability surface structures. The proposed surfaces, efficiently and eco-friendly produced through nanosecond laser fabrication, hold tremendous potential for diverse applications.

The self-lubrication property of single-phase high-entropy carbide ceramic under tribo-induced effect

Self-lubricating ceramic materials are mainly achieved through the addition of lubrication phases. Although incorporating lubrication phases can improve their tribological performances, the mechanical properties are consistently compromised. Thus, designing and fabricating single-phase ceramic with favorable self-lubricity is the relentless pursuit of researchers. In this study, the single-phase high-entropy ceramic of (Hf0.2Mo0.2Nb0.2Ta0.2Ti0.2)C exhibits self-lubricating properties and which closely relates to the testing condition. The wear rate and friction coefficient decrease with the increasing of loads (not above 30 N). And the friction coefficient of (Hf0.2Mo0.2Nb0.2Ta0.2Ti0.2)C samples against Si3N4 balls is as low as 0.3 under 30 N and 5 Hz. This originates from the carbon-rich tribo-film with self-lubricity, which is generated through diffusion and enrichment under the effect of tribo-induced. Single-phase self-lubricating ceramics—using own constituent elements to form a lubricating tribo-film—are expected to open up a new research field on the high-performance friction materials.

Synthesis and tribological characterization over a wide temperature range for A-site elements doping in Ti3AlC2

This work investigates the possibility of doping Si and Sn solid solution components (separate/simultaneous incorporation) into Ti3AlC2 to provide desired mechanical properties and tribological self-adaptability over a broad temperature range. The specimens are sintered at 1450 °C for 2 h in a vacuum environment with a pressure of 30 MPa. The phase composition, mechanical properties and tribological characteristics sliding against Al2O3 counter balls over a wide temperature range from room temperature to 800 °C are investigated. The results demonstrate considerable lattice distortion together with significant solid solution strengthening effects in quinary solid solutions. The friction coefficients of the four solid solutions are discovered to be temperature-sensitive from the distinguished variation tendencies in the wide temperature range. The wear rates exhibit a comparable tendency with test temperature that the values are two orders of magnitude lower at 600−800 °C than those at RT−400 °C. The noticeably lubricant tribofilm is responsible for the decreased wear rate at elevated temperatures. The distinct tribological behaviors of the quaternary and quinary solid solutions are ascribed to the characteristics of the self-generated oxides.

Preparation of inorganic oil-containing carbon nanocapsules and tribological properties of PA6 composites

Oil-containing polymer composites have garnered significant attention in the field of tribology due to their remarkable environmental stability and outstanding self-lubricating performance. It is important to develop an oil-containing polymer composite with excellent self-lubricating properties and mechanical properties. In this study, we successfully synthesized hollow mesoporous carbon nanospheres (HMCNs) with a particle size of about 200 nm and explored the key factors affecting their preparation. Subsequently, an impregnation technique was employed to create oil-containing nanocapsules (Oil@C) by using PAO40 lubricant as core material and HMCNs as wall material. Self-lubricating PAO40@HMCNs nanocapsules have an oil content of approximately 51.6 wt%. The unique mesoporous structure of HMCNs facilitates the controlled release of lubricants. During friction, the Oil@C in the polymer composites continuously provided lubricant to the worn surface, resulting in a remarkable 72.8 % reduction in the coefficient of friction and an 83.2 % decrease in wear rate. Analysis of the friction pair revealed that the PAO40 lubricant released from the nanocapsules played a crucial role in improving the tribological properties of the composites. The prepared PA6 composites exhibit outstanding tribological and self-lubricating properties, making them promising candidates for applications in mechanical parts, such as self-lubricating slide bearings.

Design and Material Optimization of Oil Plant Piping Structure for Mitigating Erosion Wear

Erosion in piping structures poses a significant challenge for oil industries as the conveyance of solid particles leads to operational malfunctions and structural failures affecting the overall oil plant operation. Conventional oil recovery methods have historically dominated, while in response to the challenges imposed by declining conventional oil production, the global shift towards non-conventional methods necessitates a reevaluation of erosion mitigation strategies due to increased piping infrastructure. Therefore, in this study research has been conducted to reduce erosion and optimize the piping structure. Variables impacting the erosion in piping were investigated from the literature, and simulation cases were made based on the impacted variables. Computational Fluid Dynamics (CFDs) analysis was performed using the Discrete Phase Model (DPM) to determine the erosion wear rate in each simulation case; based on the CFD results, variables with low Turbulent Dissipation Rates (TDRs) and Erosion Rates (ERs) were determined, and the optimized piping structure was designed. As a result, the optimized piping structure showed an 80% reduction in the turbulent dissipation rate and a 99.2% decrease in the erosion wear rate. These findings highlight a substantial improvement in erosion control, ensuring the safety and longevity of piping structures in oil plant operations.

Milling efficiency and wear behavior of silicon grinding media in autogenous stirred media milling

This study investigates the wear mechanisms and milling efficiency of silicon as grinding media for autogenous stirred media milling. Fresh autogenous grinding media (aGM) showed an exponentially decreasing wear rate first, while becoming constant at longer grinding times. The wear rate of used aGM was constant throughout the whole milling experiment. Shape and size analysis revealed that chipping and abrasion mechanisms dominate the wear behavior. These mechanisms led to spheroidization of the aGM. The grinding media concentration was introduced as measure for the energy transfer from the stirrer to the product particles. This concept was used for weighting the specific energy consumption. Nanoparticles of around 150 nm were obtained with similar weighted specific energy consumptions, while used aGM performed most efficiently due to their spheroidized shape. Finally, spheroidized aGM still consumed more weighted specific energy than conventional grinding media. However, a direct comparison was difficult due to the different material properties of the grinding media.