The authors studied the influence of Mo and C on the properties of the CoCrNiFeMnNb alloy system. Quasi-high-entropy alloys (QHEAs) were smelted by partially using ferroalloys in the charge, unlike classical high-entropy alloys (HEAs). The Mo content was 2 and 4% mass. The C content was 0.45% mass in the experimental alloys. The C content was determined based on the initial content in the charge. The experimental alloy microstructure was represented by a solid FCC-type solution; Laves phases of various compositions; Me1Me2-type intermetallics; carbides Nb0.8, Cr0.2C, and Mo0.5NbC; and μ-phase NbCo2. All experimental alloys had higher hardness, strength, and wear resistance than the alloy without Mo and C. Increasing the Mo content in the alloy to 4% mass increased the hardness and, in particular, the wear resistance of the alloy. Strengthening the alloy with elements Mo and C is associated with forming a finer grain. Grain growth was limited by implementation phases, as well as dispersion strengthening due to solid implementation phases of various origins being formed.
The article investigates Co-(C-Pd) multilayer coatings produced by magnetron sputtering, focusing on their structure and magneto-optical behavior. Film thickness was controlled by the number of layers, and X-ray diffraction was used to analyze structural features. Magneto-optical properties were measured by the transmission line method. Impedance spectroscopy (50 Hz–100 MHz) showed decreasing phase angle at high frequencies, indicating dielectric losses. Charge accumulation was influenced by crystallite boundaries, bulk resistance, and surface effects. Very high ε′ and ε″ values were observed, with low-frequency growth explained by Maxwell–Wagner polarization. Frequency dependence of dielectric loss and conductivity confirmed electromagnetic absorption. Thicker multilayers demonstrated enhanced magneto-optical characteristics, underscoring the potential of Co-C-Pd coatings for spintronic and data-storage technologies.
The tribological behavior of self-lubricating spherical bearings in aerospace applications is crucial for ensuring reliability under dynamic loads. This study employs Computational Fluid Dynamics (CFD) to analyze the interactions between contacting surfaces, focusing on pressure distribution, shear stress, heat flux, and elastic deformation. By simulating various operational conditions, including different rotational speeds and the use of solid lubricants like talc and graphite, the research evaluates their effectiveness in reducing friction and managing thermal effects. Findings reveal that rotational speed significantly influences tribological performance, with graphite outperforming talc in minimizing friction, heat generation, and wear at high speeds. While talc reduces friction, it induces higher shear stresses and elastic deformation, making graphite a more suitable lubricant for demanding aerospace applications. This, study contributing to enhanced performance and durability of self-lubricating bearings in critical aerospace.
The hydrodynamic plain bearing relies on the generation of a lubricant film through the rotational movement of the journal. As the journal rotates, it creates a layer of lubricant between the bearing and journal surfaces. This lubricant film separates the two surfaces, preventing direct contact and minimizing friction and wear. The high speeds can lead to severe conditions such as cavitation due to rapid oil evaporation, which introduces a new phase into the flow. In this study, it is anticipated that a two-phase flow will occur through the shaft-bushing conjunction because of the rupture of the lubricating film near the contact outlet. Pressure disturbances above these rupture zones may induce vapor-cavity formation at a small scale. A numerical analysis was conducted by solving Navier–Stokes continuity equations and vapor-transport equations. The k-epsilon model was used to analyze friction at the fluid-bearing interface for the turbulent regime. The results indicate that higher flow velocity values and pressure were observed in the case of two-phase flow compared to one-phase flow.
Photocatalytic coatings with self-cleaning properties are becoming increasingly more popular due to the increased awareness of the importance of cleaning and the associated high cost of cleaning supplies and services. This research investigated self-cleaning photocatalytic polydimethylsiloxane (PDMS)/titanium dioxide (TiO2) nanocomposite coatings and focused on selecting the optimal TiO2 phase and concentration. To date, the comparison of the different TiO2 phases as a nanocomposite coating has not been sufficiently considered. PDMS/TiO2 nanocomposite coatings with three nanomaterial (NM) samples (an anatase, rutile, and mixed phase) and three concentrations of TiO2 (0.6, 1 and 3 w/v%) were prepared, applied to glass slides by dip coating, and tested with respect to hydrophobicity, surface stability, antifogging, and photocatalytic properties. It was found that a stable hydrophobic coating with the optimal photocatalyitc performance was produced with 3 w/v% anatase TiO2.
EN-9 is one of the steel grades, and it is widely used in power plants, automobiles, and the aerospace sector. The availability and ductility of EN9 steel have been limited. Heat-treatment procedures are used to increase the hardness, wear resistance, and percentage of elongation. The main intention of this study is to discover the effect of heat treatment on EN8 steel. In this work, the various kinds of heat-treatment methods like annealing, normalizing, hardening, and tempering were carried out on EN-8 steel. Mechanical properties like hardness, tensile strength, and percentage of elongation are evaluated. The microstructure is examined and compared, before and after the heat treatment process. Hardening and tempering results indicated that EN8 steel has better hardness, yield strength, ultimate tensile strength and elongation when compared to EN9 steel.
EN-9 is one of the steel grades, and it is widely used in power plants, automobiles, and the aerospace sector. The availability and ductility of EN9 steel have been limited. Heat-treatment procedures are used to increase the hardness, wear resistance, and percentage of elongation. The main intention of this study is to discover the effect of heat treatment on EN8 steel. In this work, the various kinds of heat-treatment methods like annealing, normalizing, hardening, and tempering were carried out on EN-8 steel. Mechanical properties like hardness, tensile strength, and percentage of elongation are evaluated. The microstructure is examined and compared, before and after the heat treatment process. Hardening and tempering results indicated that EN8 steel has better hardness, yield strength, ultimate tensile strength and elongation when compared to EN9 steel.
The aim of this research is to create self-cleaning hydrophobic and superhydrophobic surfaces (SHS) on a glass substrate. Carbon soot has been deposited from the candle flame in order to manufacture a SHS on glass slides. The water contact angle (WCA) and roll-off angle were measured after carbon soot deposition using a test rig built in the laboratory. Further, to make SHS on glass slides more robust, candle wax and vassilline were applied on a glass substrate with or without roughening it using emery paper of grade (P80, P220 & P400). The highest WCA was 160° for a candle sooted on glass roughened with emery paper of grade P80 using vassilline as an adhesive. The mechanical durability of the prepared surfaces has been investigated using a peel-off technique with highly glue adhesive tape. The WCA was measured after each peel-off to check the changes in the degree of wettability of the fabricated surface. From the investigation, it has also been observed that more roughened glass slides show more resistance to the removal of carbon soot.
The lack of the sulfur beneficial lubricity in ultra-low sulfur diesel (ULSD) may lead to premature wear and failure of diesel-fuel systems. Mixing of small percentages of, for instance, biodiesels and other biofuels is typically used to add lubricity in ULSD. N-butanol has been recently proved to mix in or replace diesel without compromising engine combustion performance. But anti-wear properties of mixing N-Butanol in ULSD have not previously been studied. This paper presents a tribology study on the effects of N-Butanol in ULSD in a steel-on steel sliding contact. The research work employed a pin on disk tribometer for friction-force data acquisition, and wear was measured by specimen weight-change. The wear results and the friction force evolution observed in tests indicate that the dilutions of ULSD with N-Butanol can lead to a reduction of wear and that there is an optimum rate of dilution, of around 25% of N-Butanol in ULSD, that minimizes wear and increases the mixture lubricity as compared to those of both pure ULSD and pure N-Butanol.
Currently Aluminum alloys and polymer based fibre composites are being used for various structural applications. It is always an advantageous to have light weight high strength materials. In this context, hybrid nanocomposites are fabricated and tested for their mechanical properties to meet various applications. Due to the conflicting nature of the mechanical properties, a multi criteria decision model employing AHP (Analytic Hierarchy Process), Entropy, and TOPSIS techniques were developed with the goal of selecting an appropriate material to meet the objective out of various material combinations. A framework has been developed to assist composite structure designers in selecting the best fibre types for a given application. The purpose of this paper is to first investigate the impact of weighting methods in multiple criteria decision making (MCDM), and then to develop a systematic framework for optimum fibre selection among all fibre reinforced polymer (FRP) composites.
Composite materials assume a significant part in auto, aviation, marine, and defense applications due to its unique properties. Aluminum alloys have certain advantages over other alloys. In this paper, the composite material comprised of Aluminum Alloy LM6 and fly ash (150 – 175 μm) has been picked as lattice and supporting materials individually. Magnesium is added to lessen the surface pressure and evade the dismissal of the particles from the melts. Liquid state processing through stir casting procedure was adopted for fabrication of mmc into necessary shape and size according to the ASTM principles by energetically mixing at consistent speed and time. The fly ash with various syntheses (2%, 4%, 6%) were added with LM6 combination. XRD and EDAX were used to examine the structural analysis of MMC, and optical microscopy and SEM were used to investigate the microstructure on MMC. Wear test was also carried out on MMC to ascertain the wear rate and cof of different MMCs. There is substantial improvement of mechanical properties like tensile strength, micro hardness, and density of the composite.
An elastohydrodynamic model is applied in this work to study the influence of surface texturing on the structural performance of a coated aerodynamic plain bearing and a coated hydrodynamic plain bearing. Shaft rotational speed and radial load are digitally optimized to improve plain bearing performance, such as pressure, bearing inner face displacement, and shear stresses. Results are presented for different operating conditions. This research is carried out in order to predict the elastic behavior of a coated hydrodynamic plain bearing as well as a coated aerodynamic plain bearing at textured surface compared at a non-textured surface, operating at very high speeds. This study is a numerical investigation using a CFD code, by solving the Navier-Stokes equations of motion by the finite volume method and the displacement equations using the finite element method.
The various engineering components works under aggressive environments include the furnace parts, sliding parts in lathe machine and exhaust manifolds. Cast iron is used in these applications and important intention of this research work is to study on enhance the useful period of life.HVOF (High Velocity Oxy-fuel) sprayed Alloy-718coatings on cast iron were analysed. Coatings were characterised by field emission scanning electron microscopy (FE-SEM), Optical microscope (OM) and X-ray diffraction for its microstructural analysis. Energy dispersive spectroscopy (EDS) of the bare and coated samples was used to confirm the elemental details of the powder and the coating. Porosity measurements were taken and showed the 1.6% for Alloy-718 coating. Microhardness investigation was conducted for the Alloy-718 coating, and it was resulted as 560±20 HV. The bare material has hardness of 225±10, and there is a substantial difference of hardness found as 2.5 times higher. The fracture toughness was found to be 4.0 MPa.m1/2.
In the present numerical study, the effect of V-shape textures on the dynamic performance characteristic of hydrodynamic journal bearing is obtained by using fluid flow governing Reynold’s equation which has been solved with finite element method (FEM) by assuming that the fluid is Newtonian and iso-viscous in nature. Four different cases of texture depths/heights and distributions have been selected to compute the dynamic performance parameters (non-dimensional damping, stiffness and threshold frequency) and compared with un-textured hydrodynamic bearing. From simulated results, the maximum value of direct stiffness and damping coefficient for protruded textured bearing is found at full textured bearing and second half textured region as compared to dimple and un-textured bearing respectively. The value of threshold speed is maximum for fully textured region at higher value texture depth and eccentricity ratio for dimple textured bearing. Similarly its value is higher at higher texture height operating at lower eccentricity ratio for protruded bearings.
In the present work, experimental investigations were performed to study the effect of various machine parameters like sliding velocity (S_v), sliding distance (S_d), and load (L), on specific wear (W_s) and coefficient of friction (COF). The experiments were performed on a novel carbon fiber reinforced composite consisting of fishbone powder as filler. Response surface methodology (RSM) was used to develop the statistical models to predict the specific wear rate and coefficient of friction (µ) of the developed composite. A set of 20 experiments were designed according to the central composite design technique. Analysis of variance (ANOVA) was carried out at a confidence interval of 95% to determine the parameters that significantly affect (p<0.05) the output responses. It was also found that among the various parameters, the influence of S_d was most significant (33.4%) on W_s followed by S_v (20.3%) and L (17.9%). For COF, the percentage contribution of S_v was maximum i.e. 64%, followed by S_d (17.8%) and L (7.8%).
The present paper considers the influence of yield strength on static and dynamic behaviour of cylindrical contact interface. The semi-cylinder is assumed to be in plane stress condition. A quasi-static analysis is executed by means of finite element (FE) software package ANSYS 18.2 to obtain several contact parameters. A key parameter, quantifying nonlinearity for the single-asperity cylindrical contact system is educed from the interference-contact force plot. The dynamic characteristics of the cylindrical contact interface is investigated by utilizing this parameter. In order to investigate the same, the contact interface is represented by a single degree of freedom spring-mass-damper system and the analysis is carried out for free-undamped as well as forced-damped vibration. It is found that, with higher Young’s modulus, the dynamic contact system becomes more nonlinear in nature. It is found that, with lower value of yield strength, the dynamic contact system becomes more nonlinear in nature. Moreover, the contact system is found to possess hardening type of nonlinearity.
The emerge of Industrial 4.0 revolution and influences to production, information, and communication technologies have made manufacturers capable of reaching higher performance in the last decade. Making smart operations has been set as a top strategy of manufacturing societies, and machinery industry as an integral part of production has been highlighted develop. Aerospace, automotive, metals, glass, and plastics industries have been pioneers to improve, optimize, and develop automated polishing as a final operation of surface finishing process considering of KPIs: quality, time, cost, and safety. In this review, after mentioning the state of the art of last relevant papers, some clues for future research will be presented.
The present experimental analysis has been carried out to compare the changes in the tribological and mechanical properties of brass samples with and without heat treatment. Four Cu-Zn alloy samples are heated in various temperature ranges between 350°C to 800°C. Changes in hardness of all samples are recorded to observe the effect of temperature and time duration. Wear tests are performed in both dry and lubricated conditions. Wear loss and coefficient of friction of samples were measured at loads 20 N, 30 N, 40 N, and 50 N and at rotating disc speeds of 120 rpm, 140 rpm, 160 rpm, and 180 rpm at fixed track diameter for 8 minutes. Better tribological performance was found in the lubricating condition within the entire range of tests carried out. Minimum wear rate was observed for the samples heat treated at 650°C. The wear behavior is also investigated for both kind of samples. Deep grooving and micro ploughing phenomena are observed for non-heat-treated specimens. In the heat-treated state, the plasticity formation is more prominent.
The present study examines the effects of changes in single-wall carbon nanotube (SWCNT) volume % in an Al reinforced nanocomposite under loading and unloading in a cylindrical flattening contact. Flattening action is provided by a rigid flat, which moves downward and upward to simulate the loading and unloading stages, respectively. The cylinder is modelled as a 2D quarter-circle, which consists of the embedded CNTs. Volume % of the nanotubes is varied by changing the wall thickness and number of CNTs, while the overall radius is kept fixed. Finite element model to perform a plane stress quasi-static analysis is created using ANSYS. The simulated results are compared with results from published studies to satisfactorily validate it. Various parameters, in the contact zone and in the vicinity of the CNTs, are presented as results. It is found that above a certain CNT thickness, higher volume percentage of CNTs result in higher contact force as well as contact area. Additionally, more matrix material in the asperity is found to yield plastically for higher volume percentage of CNTs.
In this study, tribological characteristics and wear debris morphology of A390 and A515 alloys are evaluated and compared. Components with a high wear resistance slide are typically made with alloys are A390 and A515, while components with high hardness requirements are usually made up with SS410. Those alloys were used in brake pads, and SS410 steel is used for the brake disc. Speed and pad force are the two factors that affect tribological characteristics such as friction coefficient and wear rate. Wear debris and wear track were examined by scanning election microscopy and optical microscope, respectively. The effect of sliding speed variations on wear and friction coefficient at various load conditions was also evaluated, and a comparative analysis was reported based on wear rates, coefficient of friction, and debris morphology for both materials. The A515 alloys shows higher friction coefficient under all the process conditions except at very low loads and high speeds due to increased superficial hardness and the composition of the case layer (oxygen-diffused/oxide formed).
