Tribological Characteristics Research Articles

Mechanical and tribological characterization of wire arc additively manufactured SS308L component

The mechanical and tribological characterization of stainless steel 308 L, which was fabricated using wire arc additive manufacturing (WAAM), is presented in this work. Longitudinal tensile samples extracted along the deposition direction depict higher tensile strength than the transverse tensile samples. The reduction in microhardness along the build direction is associated with the temperature fluctuations the metal undergoes in the WAAM process. Ball-on-disc wear tests were performed on specimens from the top, middle, and bottom parts of the build at loadings of 20 N, 25 N, and 30 N. Furthermore; the wear analysis results showed that the top portion had the most wear at the highest load, while the bottom portion experienced the least wear under the lowest load.

Role of Quenching Temperature Selection in the Improvement of the Abrasive (Al2O3) Wear Resistance of Hybrid Multi-Component Cast Irons.

In this paper, enhancing the tribological characteristics of novel cast metallic materials-hybrid multi-component cast irons-by applying a strengthening heat treatment is described. The experimental materials were the cast alloys of a nominal composition (5 wt.% W, 5 wt.% Mo, 5 wt.% V, 10 wt.% Cr, 2.5 wt.% Ti, Fe is a balance) supplemented with 0.3-1.1 wt.% C and 1.5-2.5 wt.% B (total of nine alloys). The heat treatment was oil-quenching followed by 200 °C tempering. The quench temperature (QT) varied in the range of 900-1200 °C, with a step of 50 °C (with a 2-h holding at QT). The correlation of the QT with microstructure and properties was estimated using microstructure/worn surface characterization, differential scanning calorimetry, hardness measurement, and three-body-abrasive wear testing (using Al2O3 particles). The as-cast alloys had a multi-phase structure consisting of primary and/or eutectic borocarbide M2(B,C)5, carboborides M(C,B), M7(C,B)3, M3(C,B), and the matrix (ferrite, martensite, pearlite/bainite) in different combinations and volume fractions. Generally, the increase in the quenching temperature resulted in a gradual increase in hardness (maximally to 66-67 HRC) and a decrease in the wear rate in most alloys. This was due to the change in the phase-structure state of the alloys under quenching, namely, the secondary carboboride precipitation, and replacing ferrite and pearlite/bainite with martensite. The wear rate was found to be inversely proportional to bulk hardness. The maximum wear resistance was attributed to QT = 1150-1200 °C, when the wear rate of the alloys was lowered by three to six times as compared to the as-cast state. With the QT increase, the difference in the wear rate of the alloys decreased by three times. The highest abrasive resistance was attributed to the alloys with 1.1 wt.% C, which had a 2.36-3.20 times lower wear rate as compared with that of the reference alloy (13 wt.% Cr cast iron, hardness of 66 HRC). The effects of carbon and boron on hardness and wear behavior are analyzed using the regression models developed according to the factorial design procedure. The wear mechanisms are discussed based on worn surface characterization.

Enhancing the tribological characteristics of the biocompatible Ti-6Al-4 V alloy via heat treatment: An experimental analysis

The tribological behaviour of the Ti-6Al-4 V biocompatible alloy fabricated using laser powder bed fusion (LPBF) was experimentally investigated for prosthesis implants. Annealing heat treatment was executed to improve its tribological performance. The microstructure and microhardness characterization were performed using scanning electron microscope (SEM) and Vickers microhardness. The wear test was processed using a SS304 spherical ball in simulated body fluid (SBF) at body temperature. The ball on a flat tribometer was used to determine wear rate, depth, width, and friction coefficient at 15 N. The results revealed that a needle-like martensite α' structure was noticed on the as-deposited sample. Microstructural characterization significantly affects wear morphologies. The heat-treated specimen showed a more desirable wear performance than the as fabricated.

Highly wear resistant metal bond for diamond tool based on two-step reactive sintered Fe3Al

Metal bond diamond tools are regularly used in the machining of various hard and brittle materials. The mechanical properties and wear resistance of the metal bond are very important for the tool's life and machining performance. Herein, a low-cost and highly wear resistant Fe3Al bonded material for diamond tool was proposed. A novel two-step reactive sintering method, integrating short-term high-temperature reactive sintering and long-term low-temperature densification sintering, was proposed to prepare Fe3Al bond diamond tools. The effect of sintering temperature on the microstructure and mechanical properties of the Fe3Al bond was examined during one-step reactive sintering. The mechanical properties and tribological characteristics of the one-step and two-step reactive sintered Fe3Al and commercial Fe alloy bond were compared. The machining performance of the two-step reactive sintered Fe3Al bond diamond tool on sapphire was also examined and compared to that of a commercial Fe alloy bond diamond tool. The results showed that the relative density and mechanical properties of the Fe3Al bonded material were enhanced by increasing the sintering temperature during one-step reactive sintering. Moreover, the sample sintered at 1150-850 °C exhibited better mechanical properties and wear resistance compared to the one-step reactive sintered Fe3Al and commercial bond. The grinding ratio of the two-step reactive sintered Fe3Al bond diamond tool was 157 % higher than that of the commercial Fe alloy bond diamond tool.

Study on the Tribological Properties of Multilayer Concentric Hexagonal Laser Texturing on Rubber Surfaces of Screw Pumps.

Given the friction and drag reduction effects observed in various biological hexagonal structures in nature, a new design was implemented on the rubber surface of the stator of a submersible screw pump. This design featured a multilayer concentric hexagonal groove structure. Furthermore, a composite multilayer hexagonal structure integrating grooves and pits was also developed and applied. This study investigated the influence of groove layer number, groove depth, pit depth, and multilayer hexagonal groove texture arrangement on the rubber surface flow characteristics. Additionally, the pressure field state, the degree of influence on the oil film-bearing capacity, and the biomimetic and hydrodynamic lubrication theories were tested using the finite element analysis method. Tribological experiments were conducted on nanosecond laser-processed rubber textures under simulated liquid lubrication conditions, reflecting actual shale oil well experiments. These experiments aimed to investigate the influence of multilayer hexagonal shape parameters on the tribological characteristics of the stator-rotor friction pair of a submersible screw pump. The results indicated that with a constant overall size, a multilayer hexagonal structure with ~0.1 mm groove depth enhanced the oil film-bearing capacity, providing significant friction and drag reduction. For composite textures, a deeper pit depth within the study area enhanced the oil film-bearing capacity. Furthermore, a gradient arrangement of groove textures featuring wider outer grooves and shallower depth exhibited superior performance in terms of bearing capacity.

Physio-mechanical and tribological characterisation of sintered aluminium 7068 modified with NiTiFeAlCu high-entropy-alloy for engineering applications

ABSTRACT Metal particles are gaining attention as reinforcement in metal matrix composites owing to their ductility as compared with ceramic particles, which are inherently brittle. High-entropy-alloy (HEA) particles belong to this category based on their high strength, ductility, and thermal stability. Aluminium-7068 is a new aerospace alloy in the 7000 series that possesses higher strength than aluminium-7075, yet very few studies have considered reinforcement with high-entropy alloy particles. For strength improvement, NiTiFeAlCu (HEA) powder was introduced into the aluminium-7068 matrix at 0, 4, 8, and 12 wt. % at 500 °C via vacuum sintering. The microstructure depicted dispersed particles in the matrix with a linear reduction in porosity as the HEA dosage increased. Consequently, there was a linear increase in density and relative density. 4–12 wt.% HEA engendered linear improvements in yield and ultimate tensile strength, elastic modulus, and hardness; meanwhile, elongation was a progressive decline. The outcome of this study shows that HEA particles in AA-7068 resulted in an improvement of the tensile and hardness properties. The particle addition was observed to reduce the composite’s friction coefficient and wear rate. This report revealed that the performance of AA-7068 can be improved up to 12 wt. % NiTiFeAlCu HEA addition.

Functional behaviour of novel multi-layered deposition via twin wire arc additive manufacturing: Microstructure evolution and wear tailoring characteristics

Twin wire arc additive manufacturing offers advantages such as high deposition rates and the ability to use a wide variety of materials, making it suitable for large-scale metal part production with enhanced efficiency and flexibility. Functionally graded deposition (FGD) based structure of dissimilar steels (SS316LSi and ER70S-6) fabricated via twin wire arc additive manufacturing and their detailed performance analysis are accomplished in the current research work. Microstructural, mechanical, and tribological characteristics of the deposited structure were investigated and analysed. Microstructure reveals polygonal ferrite, widmanstatten ferrite, skeletal ferrite, lathy ferrite, ferrite solidification, and ferrite to austenite (F/A) transformation. FGD structure possessed a microhardness of 371 HV. Average ultimate tensile strength, yield strength, and elongation percentage were 675.98 MPa, 414.21 MPa, and 38.37 %, respectively. In wear analysis, the average coefficient of friction value of WAAM-processed FGD samples is 0.44–0.49. 3D profilometer analysis reveals that average values of roughness, maximum height of roughness, and maximum roughness valley depth are significant with increasing applied loads. The findings of the present research focus on the quality and appropriateness of dissimilar steels for structural applications and provide a novel method for creating high-strength components.

Injectable Boron Nitride‐Hyaluronic Acid Hybrid Hydrogels to Facilitate Joint Motion: Mechanical and Tribological Characterization

AbstractHexagonal boron nitride (hBN) is used as an additive in engineering applications such as polymers, ceramics, and coatings because of its anti‐wear and lubrication performance. It has a high potential as a biomaterial, but it has not been evaluated to facilitate joint motion with its lubricating properties until now. In this study, the hypothesis that boron nitride nanoparticles (BNPs) and nanosheets (BNNSs) can facilitate movement in the joint region is evaluated for the first time. Hyaluronic acid‐based hybrid hydrogels are designed to transport BN particles to the target area and pin‐on‐disc tests on cartilage pins paired with glass disks are conducted to determine the validity of the proposed hypothesis. The injectability, mechanical properties, and friction coefficients of hydrogels with the addition of increasing proportions of different hBN morphologies are monitored. As a result, hyaluronic acid has been found to be a suitable carrier for the injectability of boron nitride in biomedical applications. The amount and morphology of boron nitride are observed as two important parameters. A significant decrease in the friction coefficient (18.9%) is observed in the BNNS‐doped hybrid hydrogel compared to the virgin hydrogel. hBN can be considered as a new therapeutic agent with the potential to facilitate joint mobility.

Influence of droplet-free ta-C coatings and lubrication conditions on tribological performance and mechanical characteristics of WC−Co

Cemented carbide (WC−Co) tools suffer from surface abrasion, limiting their performance. This study explores droplet-free tetrahedral amorphous carbon (ta-C) coatings deposited via arc ion plating as a solution. The coatings possess a dense, sp3-rich structure, leading to a remarkable hardness of 60 GPa compared to 37 GPa of WC−Co, and strong adhesion with a critical scratch load of 41 N. Tribological tests confirm their effectiveness. Dry sliding tests show reduced wear and lower CoF (0.123) compared to uncoated tools (0.159). Notably, water-soluble lubricants yielded the best performance (lowest CoF: 0.092, superior wear resistance), while water and mineral oil also improved performance.

Exploring the tribological impact of micaceous additives in copper‐free automobile brake friction composites

AbstractThis study investigates the tribological impact of incorporating micaceous additives in copper‐free brake friction composites for automotive applications. Four brake pad formulations were created, each containing different amounts of muscovite and phlogopite, ranging from 0% to 10% by weight. A brake pad comparison was conducted by replacing mica with synthetic barites. The physical, thermal, mechanical, and chemical properties of the fabricated brake friction composite were examined. Tribological features were evaluated through inertia brake dynamometer testing following the JASO‐C‐406 schedule. Scanning electron microscope (SEM) analysis delved into contact plateau formations and back transfer patches on the brake pad's surfaces. Notably, phlogopite‐based pads exhibited enhanced thermal stability and efficient heat dissipation, contributing to sustained tribological performance. Overall, the comprehensive evaluation using the multiple objective optimization by ratio analysis (MOORA) method positioned phlogopite‐based brake pads as the optimal choice for optimized braking performances.Highlights Exploration of micaceous additives as an ingredient in brake friction composite. Phlogopite‐based brake pads showed better fade and recovery performance. Phlogopite‐based brake pads exhibited low pad wear and rotor wear. MOORA optimization positioned phlogopite‐based brake pads as the optimal choice.

Microstructural and mechanical properties of Al-Al2O3 micro and nanocomposite fabricated by stir casting

ABSTRACT The current study examines the relationship between the microstructure and tribological characteristics of Al-Si alloy composites reinforced by secondary phase nano SiC particulates synthesis via the stir casting process. The results of wear testing of stir-cast SiC metal matrix composites including up to 12 weight percent fine (75–100 µm) and coarse (125–150 µm) size particles were obtained from cast aluminium alloy. It was discovered via microstructural investigation that the aluminium alloy and SiC particles have good interface bonding. However, at greater amounts (12 wt.%) of fine size reinforcement, clustering of reinforced particles is observed. In addition, results state that finer size particles agglomerate more in the matrix than coarser size particles at greater reinforcement levels. In addition, increasing the amount of SiC particles in the matrix enhanced the hardness of the base alloy. However, when the size of the SiC particles was reduced, the hardness of the composite increased dramatically. Better wear resistance was observed for higher SiC reinforcement levels, while higher forces were also associated with a corresponding increase in wear rate. A combined mode of adhesive and abrasive wear mechanisms is responsible for composite wear, according to a scanning electron microscopy (SEM) investigation of worn surfaces.

Tribological properties and synergistic effects of ionic liquids and silver complexes

PurposeThe purpose of this paper is to solve the abrupt deterioration of lubricant performance in high-temperature conditions.Design/methodology/approachThree silver pyrazolyl methyl pyridine complexes with different morphologies were synthesized. A four-ball tribometer was used to assess the tribological characteristics as an additive for pentaerythritol oleate both independently and compound with 1-hexyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide.FindingsThe results showed that when silver complexes and ionic liquids (IL) act independently, sheet silver complex 1 and rod silver complex 2 exhibit good lubricating performance; the optimal antifriction concentration of the ILs is 0.25 Wt.%. The tribological results of the compounds additive of ILs and silver complexes indicate that the wear scar diameter of compound 1 decreased by 16.914%, the wear volume reduced by 7.44% and the lubrication effect surpassed that of the two substances individually; rod compound 2 exhibited an antagonistic effect, intensifying wear; compound 3’s lubrication effect fell between that of the two individual components.Originality/valueThe compound of sheet silver complexes and ILs effectively solves the agglomeration problem of micro/nano lubricant additives. When the interface fails, self-repair is completed, improving the stability and antiwear performance of the lubricating oil.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0128

Atomic-scale tribological behavior of pressure-induced MoO3(0 1 0)/Ag(1 1 1) heterogeneous sliding interface

The atomic-scale tribological properties of the MoO3(010)/Ag(111) heterogeneous sliding interface were studied by first-principles calculation method. The interface binding energy, sliding potential energy, friction force, charge density difference, partial density of states, Mulliken bond population and HiRshfeld charge were analyzed, and the essence of the friction was revealed. The results show that the sliding potential energy and friction exhibit anisotropy for the pressure-induced MoO3(010)/Ag(111) heterogeneous sliding interface. The friction force can be described by the change of the sliding potential energy, and the charge redistribution between interface atoms is the intrinsic reason for the change of tribological properties. This work provides atomic and electronic level insights for understanding the tribological characteristics between two-dimensional materials and soft metals.

Tribological and microstructural characteristics of Al2O3–LM6 semi-solid cast composite synthesized by dual mixed slurry process

The purpose of this work is to analyze the impact of reinforced Al2O3–LM6 aluminum composite made with dual mixed slurry for semi-solid casting with stirring, which is documented according to microstructure and wear properties. Under dry sliding pin-on-disk conditions, the composition and surface morphology of worn surfaces were carefully examined for the 10 N applied force, 1.2 m/s sliding speed, and sliding distances up to 750 m. Experimental findings indicate that Al2O3 reinforcement with semi-solid dual slurry effects give outstanding resistance against the adhesive wear. Microstructure, EDS, and XRD results from worn surface evaluation all show evidence of protective layers, which helps explain the reason for the rate of wear decreased due to processing. In this experiment, LM6 serves as the matrix material and Al2O3 as reinforcement. Al2O3–LM6 semi-solid cast composite was created via a dual mixed slurry technique with temperature control close to the solidus line for varying compositions. This work reports a substantial relationship between metallurgical and mechanical parameters. Mechanical properties and wear characteristics have been investigated.

Study of tribological characteristics of micro-arc calcium phosphate coatings on titanium

Tribological characteristics of implants, such as wear resistance and friction coefficient, play a critical role in ensuring their durability and functionality when interacting with surrounding tissues. These parameters influence the implant's ability to withstand mechanical loads and minimize wear throughout its service life. Minimizing friction between the implant and biological tissues not only helps prevent mechanical damage but also reduces the risk of inflammatory reactions, ensuring better biological compatibility. In this study, calcium phosphate coatings were obtained using the micro-arc oxidation method with different duty cycle of current to investigate their tribological characteristics. The coatings deposited on titanium had a structure with volcano-like formations with pores ranging from 66 to 98 micrometers. The thickness of the coatings varied from 74.3 to 100 micrometers depending on the conditions during microarc oxidation. Tribological tests were conducted using a ball-on-flat setup with reciprocating motion. The coatings were subjected to tribological tests against SHX15 steel under normal loads of 5 and 20 N. Depending on the applied load, the friction coefficients of the coatings ranged from 0.029 to 0.034 at 5 N and from 0.9 to 1.26 at 20 N. Analysis of wear parameters and micrographs of worn surfaces indicate that the mode with a pulse current duty cycle of 17.3% during micro-arc oxidation allows for the production of titanium surface coatings with high wear resistance.

Tribological behavior and characteristics of TIG surface cladded AlCoCrFeNi high-entropy alloy on 304L stainless steel

The present study examines the tribological properties of AlCoCrFeNi high-entropy alloy (HEA) surface cladded on 304L stainless steel via a Tungsten Inert Gas (TIG) heat source. Commercially pure powders of aluminum, cobalt, chromium, and nickel were ball-milled, mixed in specific ratios, and applied onto the substrate with polyvinyl alcohol as a binder. Cladding was performed with optimized parameters to create layers of HEA. Microstructural and EDS analysis revealed equiaxial dendrites rich in aluminum and nickel in dendritic (DI) areas, and rich in iron, chromium, and cobalt in interdendritic (ID) areas. Mixing entropy was calculated by consideration of EDS analysis of the cladding and based on the initial definition of a high-entropy alloy, the high-entropy nature of the cladding was confirmed. XRD analysis showed the presence of FCC, A2/B2, and hard σ phases. Surface alloyed material exhibited higher hardness compared to the base material, with an average of 540 HV versus 200 HV. A pin-on-disc wear test machine was used to assess tribological properties under different loads of 10, 20, and 40 N. The wear rates of the high-entropy cladded material were 36 and 50 % less than those of the 304L stainless steel under applied loads of 10 and 40 N, respectively, while their wear rates were almost similar at 20 N. Friction coefficients of HEA pins were notably lower than 304L at 10 and 20 N, with smoother profiles. Wear mechanisms of the HEA material varied with load: oxidative wear at 10 and 20 N due to the formation of an oxide layer, and abrasion and spallation at 40 N, resulting in a threefold increase in wear rate at this load. Overall, the study highlights the effectiveness of HEA cladding in improving tribological properties, especially under high applied load.

Tribological characterization of the cooling performance when applying cryogenic coolants and minimum quantity lubrication

Cryogenic minimum quantity lubrication (MQL) offers the potential to combine high cooling capacities, advantageous lubrication effects and a significant reduction regarding resource consumption. However, due to the wide range of machining applications and different load cases, an efficient design of the respective supply strategy is comparatively difficult. In this study, a tribological approach is presented that enables a characterization of the cooling and lubrication properties in dependence of the supply strategy and two representative load cases. The results show that the tribological setup is well suited to evaluate the occurring thermomechanical loads in dependence of the cryogenic MQL strategies applied.

Investigating and predicting tribological characteristics of AZ31 alloy composites reinforced with nano-Al2O3 and micro-Sn particles: a comparative analysis using CCD-RSM and ANN models

In this research, the central composite-based response surface methodology was adopted to select the dominant optimal input factors on wear behaviour and coefficient of friction of an AZ31-microtin/2 wt% nano-Al2O3 composite prepared through a stir casting process with different wt% of Sn. The input factors, such as wt% of Sn reinforcement, sliding distance, sliding speed, and applied load, were selected to determine their significant effects on the coefficient of friction and wear behaviour with 30 trial runs. Analysis of variance (ANOVA) results indicated that Sn reinforcement plays a significant role in the wear behaviour of the nanocomposites, followed by applied load and sliding distance. In addition, an enhancement in wear resistance was witnessed by the addition of Sn reinforcement with AZ31/nano-Al2O3 composites. The optimal process parameters as per the desirability approach were found to be a weight percentage of Sn: 8%, load: 20 N, sliding speed: 2 m s−1, and sliding distance: 1000 m. According to the ANN results, the predicted data is perfectly acceptable with the actual experimental response value. The R values for the training, validation, and testing phases are 0.96166, 0.96801, and 0.98914 for COF, and 0.97688, 0.99247, and 0.99331 for wear rate, indicating a robust correlation between predicted and actual values. The worn-out pin samples were used to examine the worn surface morphology and analyze the wear mechanism.

Tribological and mechanical properties of FSW joints of untainted stainless steel and titanium: novel characterization of similar and dissimilar joints

Friction Stir Welding (FSW) is an emerging solid-state welding process that joins dissimilar or similar metals based on requirements. The additional material to make the joint is also a weight reduction factor deemed vital in weight-sensitive industries like aerospace and orthopedic applications. The similar and dissimilar Ti-6Al-3Nb-2Zr-1Mo (Ti6321) and stainless steel (SS 310) joints are performed through friction stir welding. This investigation aims to identify the effect of process parameters on the mechanical behavior and microstructural characteristics of the FSW joints. Five plates are chosen; three are FSW joints, and two are kept in the original base material. In all five plates, tensile, microhardness, and wear tests are performed, including an analysis of grain size. It is observed that the similar Ti6321 joint with a 6 mm pin diameter, 60 mm transverse speed, 900 mm rotational speed, and a constant axial force of 1 KN exhibits a maximum microhardness of 362 HV and a tensile strength of 927 MPa when compared to other joints. The tribological properties are identified as varying load (10–50 N), sliding speed (1–5 m s−1), and a constant sliding distance (1000 m) on pin-on-disc apparatus. It reveals that welding parameters and tool diameter influence tribological characteristics. The surface morphology carried out by FE-SEM revealed that the HAZ is composed of acicular α. The increase in microhardness is higher in WC than in BM due to the uniform distribution of particles. The chemical composition and phases are analyzed using XRD.

Effect of High-Speed Longitudinal Ultrasonic Vibration-Assisted Milling on Tribological Characteristics of a Plane Surface

Effect of High-Speed Longitudinal Ultrasonic Vibration-Assisted Milling on Tribological Characteristics of a Plane Surface