Abstract Three groups of ultra-high-molecular-weight polyethylene (UHMWPE) with optimum hydrophilicity were obtained by halogenation modification. They were immersed in a 15% KBr solution for 30 h, a 10% NH4Cl solution for 60 h, or a 15% NH4Cl solution for 60 h. The mechanism of hydrophilicity enhancement by halogenation modification was investigated by combining surface morphologies and energy spectrum

ABSTRACT Friction and wear behavior of nickel base hardfacing alloys ER NiCr-A, ER NiCr-B and ER NiCr-C (ER: electrode rod, NiCr: Nickel Chromium) deposited over austenitic stainless steel was studied against silicon carbide counter body by ball-on-disc tribo testing at 25 °C (1 bar pressure, 3 × 10−5 mbar vacuum) and at 550 °C (3 × 10−5 mbar vacuum) temperature. The wear tracks were examined using

Abstract High-speed, high-load railway development has necessitated a deeper understanding of the wear behaviour and mechanism of welded steel railway joints subjected to repeated impact. Under different simulated impact loads and impact cycles, the impact damage evolution and wear mechanism of flash- and aluminothermic-welded joints in the weld and heat-affected zones and base material were compared

ABSTRACT The instability of oil film stiffness in mixed elastohydrodynamic lubrication (EHL) is a prominent cause of the fretting wear of continuously variable transmission pulley–metal sheet friction pair. In severe cases, it can induce dynamic system failure. In this study, an oil film normal stiffness model equivalent to a massless spring element is established using linear contact mixed EHL theory

Abstract In this study, a comprehensive thermoelastohydrodynamic model considering turbulence and cavitation is developed. After comparing the Reynolds-Rayleigh-Plesset and Elrod and Adams models, the EA model is adopted to consider cavitation effects. To validate the developed model, a series of novel two-phase flow or mixed bubble experiments is designed by extracting the characteristics of actual

Abstract The wear behaviors of 4145H drilling tool steel in water-based slurries were investigated under the conditions of various concentrations of SiO2, Al2O3 and SiC sands using a modified ASTM B611 rubber ring wet grinding test system. Under the identical conditions, the measured wear loss was positively correlated with the sliding distance, abrasive hardness as well as sand concentration. However

Abstract Wet clutches are widely used in vehicle transmission systems to start and shift. The temperature field of the wet clutch components is influenced by friction and is closely related to the vehicle performance and service life. This work improves the numerical modeling of the temperature field by taking into account groove cooling, local heat dissipation, and the time-varying friction coefficient

Abstract Due to the unique redox characteristic of CeO2, the addition of CeO2 in diesel fuel reduces diesel engine emissions; however, its influence on the friction and wear performance of fuel injection systems is not clear. In this work, CeO2 was synthesized and modified. CeO2–diesel fuel blends with different concentrations were prepared. The dispersion stability of the CeO2 and modified CeO2 in

Abstract The different fretting wear behaviors of alloy 690TT in air and in a flowing nitrogen environment were revealed. Moreover, grain refinement to the nanoscale caused by fretting wear in nitrogen was investigated. The results showed that when compared with an air environment, the coefficient of friction in nitrogen was slightly higher due to direct contact between the metals with strong adhesion

ABSTRACT Microturbomachinery implements gas bearings to produce significant power with high efficiency at high rotor speed operation. Externally pressurized porous (EPP) gas bearings allow nearly friction free operation. Presently, this paper presents rotor dynamic tests conducted with a large and heavy rotor (100 mm in outer diameter and 285 N in weight) supported on a pair of five-tilting pad EPP

Abstract To improve the tribological property and suppress the friction-induced noise of Ti-6Al-4V alloys (TC4), TC4 with smooth surfaces (TSs), groove anti-friction surfaces (GAs), Sn-Ag-Cu coating surfaces (SCs) and composite self-lubricating surfaces (CSs) with grooves and Sn-Ag-Cu coating were prepared, respectively. Experimental studies on the tribological properties and friction-induced noise

We investigated superparamagnetic nanolubricants and verified the influence of the magnetic field, particle size, and concentration on the tribological performance. The superparamagnetic nanoparticles were synthesized with two different sizes (7 and 15 nm) and dispersed in mineral oil with concentrations of 0.2 and 0.4%wt. The tribological tests were performed using a HFRR tribometer, with and without

ABSTRACT The effect of SrAl2O4, FeAl2O4 and FeO derived from the solid state reaction between Fe, Al and SrSO4 during the hot pressing sintering process on the tribological properties of Fe-Al-SrSO4 (FA-SrSO4) composites was investigated between room temperature and 1000 °C. The results indicated that the formation of SrAl2O4, FeAl2O4 and FeO had an impact on the friction coefficient and wear rate

ABSTRACT A Cu-free brake friction material was produced with three surface scorching conditions, and the brake performance was compared using maps of the friction coefficient, maximum disc temperature and deceleration. The tests were carried out using a sub-scale dynamometer to avoid any hardware influence on the obtained brake data. The friction coefficient decreased with velocity and contact pressure

Abstract The objective of this study is to evaluate the correlation between noise and friction variation through an analysis of data obtained from relative motion of headlining and panel. Tests were conducted using headlining and panel specimens cut from the actual vehicle. The effect of surface roughness on noise was investigated by comparing textured headlining A with non-textured headlining B. To

Abstract In previous work, a monomolecular lubricant layer was applied on coin blanks by a burnishing process. With this layer, not only was the die life increased three times but the coin surfaces were protected from tarnishing. In this work, a monomolecular octadecanethiol layer was applied on the surface of silver coins by ultrasonic bathing. After an organic accelerated sulfurization test, the

ABSTRACT In the present study, a series of Ni + xCr7C3 (x is the weight fraction of the Cr7C3) clads on hydro turbine steel (CA6NM) were developed through microwave cladding. The weight fraction of Cr7C3 was 10 wt%, 20 wt% and 30 wt% in the developed clads. These clads were developed to mitigate the erosion induced degradation of the substrate surface. The Ni +10% Cr7C3 composite clad exhibited poor

In rotating machines, tilting pad bearings (TPJBs) are widely used due to their enhanced design stability in comparison with alternative bearing configurations. In the present research, a thermohydrodynamic (THD) lubrication model for a tilting pad bearing with injection is developed. Within the THD lubrication model, the lubricant is also fed into each pad through a central injection orifice. The

ABSTRACT In order to investigate the effects of the oil film between deformed disks on the dynamic torque behavior of hydro-viscous drive (HVD), a mathematical model incorporating film lubrication, asperity contact, translational and rotational motion from a friction system is developed based on four kinds of representative film gap cases. The main analytical solutions including squeeze velocity, angular

Abstract Measurement of the antioxidant additives during lubricant thermal degradation is a useful method for providing a quantitative basis to understand the performance of the lubricant. In this study, a synthetic ester-based aviation oil was thermally exposed for a period of 500 hours under gas turbine aero-engine representative conditions using Lubricant/System Interaction Simulator (L/SIS) test

ABSTRACT C/C-SiC composites with different SiC content was fabricated by reactive melt infiltration of silicon with four types of porous C/C composites, which are prepared through chemical vapor infiltration. Compared with the high-density C/C composites and silicified graphite, the C/C-SiC composites demonstrated excellent balance of mechanical properties, especially impact toughness. The results

Through the introduction of gas-phase monomers phthalic anhydride (PA) and p-phenylenediamine (PPD), replenishment of lubricants during high-temperature friction process could be realized. In a 10-minute ball-disk friction at 500 °C, introduced monomers would contact and polymerize in gas-phase to form solid products with the structure of imide or long carbon chain according to FT-IR and GC-MS, which

This paper presents an efficient cavitation model for fluid film bearings, considering both gaseous and vaporous cavitation. This work presents a modification of the Elrod cavitation algorithm, where the bulk fluid is similarly considered to be a mixture of liquid and bubbles, without the need for a switch function. By solving for properties of the bulk fluid in the film, the distribution of the gaseous

Abstract Excessive torque on tool surfaces resulting in friction and wear in the process of well drilling remain a big challenge for the oil/gas exploration industry. In this study, two kinds of glycerides are encapsulated serving as lubrication additives to improve the tribological properties of water-based drilling mud. It is found that encapsulation has improved the thermal stability of microcapsules

Abstract Disc brakes are widely used in various kinds of light vehicles. Currently, it has become a tendency to reduce the mass and volume of brake systems because of the increasing lightweight requirement for vehicles, especially for passenger vehicles in populated cities and for outdoor sport. However, there is often conflict between light weight and reliability. In this article, the braking characteristics

Abstract Most magnetic fluid seals are multitooth structures for the high sealing capacity. However, the pressure transfer mechanism in the multitooth magnetic fluid seal is only carried out through experimental methods. In this article, a simulation method is presented to solve the two-phase flow of magnetic fluid and air in the sealing clearance. The boundary of the magnetic fluid is obtained by

Abstract A solid contact model with high accuracy is required for mixed lubrication calculation to predict friction loss and wear in sliding parts by computer-aided engineering; however, existing models have numerous limitations. A new asperity contact model was constructed to determine contact states using the roughness parameters of pairs of surfaces. Although the contact states differed greatly

Abstract During acceleration and deceleration processes of a bearing, the kinetic relationship of collision and friction between the cage and the rolling element is complex, which has an important influence on the dynamic characteristics and stability of the rolling bearing. In this study, experimental investigation of the dynamic motions of a cage under various external radial loads was performed

ABSTRACT In recent years, the porous bearings are being increasingly used in various industrial applications because they are less noisy, have good precision, and are relatively maintenance free. In this article, the numerical analysis of conical porous hybrid journal bearing system (CPHJBS) has been carried out. The interactive effects of permeability parameter, semi cone angle and pseudoplastic (shear

Abstract To study the dynamic support characteristics of an auto-eliminating clearance auxiliary bearing (ACAB) after a rotor fall, this paper proposes a parameter identification method based on the finite element method (FEM). First, a dynamic model of the magnetic suspension bearing–rotor system was established. Next, the support-stiffness and damping matrices of the ACAB were deduced, and the feasibility

Abstract An extended Reynolds equation is presented to evaluate the effects of the fluid inertia and cavitation on the performance of a spiral-grooved mechanical face seals at the high-speed conditions. The segregated finite element procedures are employed to solve the fluid inertia terms and the fluid film pressure distribution with the artificial viscosity stabilization strategy and Streamline-U

Abstract Chain continuously variable transmissions (CVTs) are attracting attention as the next-generation practical application and utilize lubricated rolling–sliding contacts for transmitting the engine power. However, their flexible structure sometimes causes vibration and noise problems that need to be solved. In this study, friction tests were conducted for a rolling–sliding contact lubricated

Abstract Water-miscible metalworking fluids (MWFs) are used in metal removal and forming operations. For end use, formulation concentrates are diluted in water, providing conditions conducive to microbial growth and metabolism and potentially causing fluid biodeterioration and microbiologically influenced corrosion. Microorganisms in the environment are highly diverse, and bacteria and fungi have been

ABSTRACT The present work aims to investigate the synergetic effect of Titanium Dioxide (TiO2) and graphene (GnP) nanoparticle additives on rheological and machining characteristics of biodegradable vegetable oil (Rice bran). The rice bran oil has been used in turning of M2 steel using Minimum Quantity Lubrication (MQL) technique. The effect of varying concentrations by weight (0.5 wt.% and 1 wt.%)

Abstract In this study, a rough surface thermal elastohydrodynamic lubrication (TEHL) model tailored for the simulation of high-speed and high-temperature contacts of relatively smooth surfaces is introduced. The model uses a modified Carreau-Yasuda constitutive function to capture the non-Newtonian effects and a limiting shear formulation to consider any lubricant–solid slippage. It is employed to

Abstract High-temperature tribology of steel components is typically characterized by high friction and excessive wear, which need to be addressed. In the present study, the tribological properties of an alkali borate were evaluated in a steel contact by ball-on-disc testing over a wide range of temperatures (600–800 °C) and loads. The compound exhibits good lubrication performance consistently throughout

ABSTRACT Oxygenated fuel is recognized as an effective alternative fuel for the petrochemical industry. Studies have shown that using a mixture of dimethyl carbonate (DMC) and diesel fuel can help reduce soot emissions. Due to incomplete combustion of some diesel fuel, a small amount of fuel will inevitably enter into the engine oil and cause engine oil dilution. Herein, the tribological properties

Abstract In gas foil bearings, frictional contacts are one of the main factors that affect the bearing performance, which are highly nonlinear as well. Using finite element method, this paper presents a nonlinear model for static performance analysis of the foil bearings based on frictional contacts. The model incorporates the top foil and the interactions between bumps by modeling the foil structure

ABSTRACT The tribological performances of polymer stabilized TiO2 particles dispersed in mineral base oil were investigated. Two polymer/TiO2 mass ratios were investigated, with a constant polymer concentration of 0.3 wt% and two nanoparticles concentrations of 0.1 and 1 wt%. Friction tests were carried out with a pin on a reciprocating flat test configuration under boundary lubricated sliding conditions

Abstract The elastohydrodynamic (EHD) lubrication straight line contact conjunction is studied to evaluate the mixed lubrication heat generation experimentally over bordering operating conditions in a disc-on-disc machine. An experimental investigation is carried out using an accessory device that collects and measures the outlet lubricant temperature. The experimental results show the typical transition

Abstract A grooved texture surface was fabricated to enhance the wear resistance of the guide rail surface of molding machine. The effects of sand concentration in the oil and the groove width on the tribological properties were studied using a pin-on-disk tribometer. Surfaces with groove widths of 1000 μm (S1) and 1500 μm (S2) had lower friction coefficient and better anti-wear properties than a non-grooved

Abstract CoCrMo alloys are commonly used in artificial joints. However, tribocorrosion phenomena have led to the search for improvements to diminish wear debris and ion release. Engineering of surfaces is an alternative to achieve this purpose. In the present study the tribological effect of AlCrN, AlTiN, AlTiON, and AlCrON coatings deposited on cast CoCr alloy was investigated. The coatings were deposited

Abstract To explore the mechanisms of squeak generation in automotive interior, the stick-slip experiments of polypropylene verse leather were conducted under various conditions. The friction properties were researched with the normal force, velocity and temperature changing, then the static friction coefficients were generally smaller at low temperature, larger at room temperature, and intermediate

ABSTRACT Epoxy is a polymeric material that is widely used in various fields as an adhesive, coating, and bulk material due to its outstanding properties. Many researches about reinforced polymers have been conducted by adding micro/nano particles or fibers to attain better tribological properties. However, the tribological properties of patterning on epoxy surface are relatively obscure. In this study

Abstract A test apparatus is described which evaluates the performance of static aviation seals under an environment similar to the lubrication system in gas turbine engines. The seals can be tested at operating temperatures as high as 400 °C in the static seal rig (SSR). Incorporating an air/oil mist generating system, the test facility exposes the seals to degraded oil, which can deteriorate the

ABSTRACT In this paper, the synergistic effect of the addition V and Nb on CoCrFeMnNi high-entropy alloy (HEA) coating prepared by plasma cladding was studied. The results shown that the additions of V and Nb promoted the precipitation of intermetallics in the HEA coating and had no effect on the FCC structure of the matrix. The CoCrFeMnNiVNb composite coating presented complex phases structure including

ABSTRACT The difference in wear behaviour of superelastic NiTi and conventional Ti6Al4V alloys with similar elastic limits was investigated. Reciprocating dry-sliding wear tests were performed with a ball-on-plate tribometer machine at different normal loads and sliding times. Mechanical properties were also examined using different microindentation tests, and wear track morphologies and chemical compositions

Abstract The failure of moving mechanical components is often accompanied by hydrogen embrittlement caused by hydrogen diffusion in steel. One considerable mechanism for hydrogen diffusion is its ingress from lubricant decomposition. We quantitatively investigated the ingress of hydrogen generated by lubricant decomposition into bearing steels using time-of-flight secondary ion mass spectrometry (ToF-SIMS)

Abstract This work presents a study on the tribological behavior of surfaces obtained by turning in sintered self-lubricating composites. Turned surfaces were obtained at constant cutting speed (vc = 100 m/min), feed (f = 0.2 mm), and depth of cut (ap = 1 mm). The tested composites have solid lubricants (graphite and hexagonal boron nitride, h-BN) mixed in an Fe-C-Ni-Si matrix manufactured by single

Abstract The effect of annealing treatment on the wear performance of hot-rolled wear-resistant steel–carbon steel–cladded plates was investigated. A novel cladding procedure that can provide high wear resistance, a strong structure, and low cost is typically employed for metallurgical mining equipment, agricultural machinery, coal mining, and other industries. The cladded plates were first annealed

Abstract AISI D2 steels are an interesting family of tool steels that generally have applications in knife blades, shaper blades, and forging and punching dies due to its optimum toughness, lower wear rate, and relatively high hardness. The present research work aims to design a new heat treatment cycle consisting of single tempering followed by cryogenic treatment and soft tempering to improve the

Abstract Carbon fiber–reinforced polymers (CFRPs) are often exposed to solid particle erosion wear due to small particles moving freely in the atmosphere or in the environment and their impact on aircraft bodies. In this study, fiber weaves of CFRP composite materials of the following types were produced: unidirectional (U), plain weave multidirectional (P), and twill 2 × 2 weave multidirectional (T)

Abstract The frictional vibration generated in water-lubricated rubber bearings operating under low speed, heavy load, startup and shutdown conditions can severely degrade the reliability and the sheltered performance of underwater vehicles. The rubber layer of the ship stern tube water-lubricated rubber bearings is easily elastically deformed under certain loads, which affects the damping performance

Abstract Ni-Ti-C metal matrix composites (MMCs) with in situ formed, homogeneously distributed titanium carbide (TiC), as well as graphite (C) reinforcement in the nickel metal matrix, were synthesized using mechanical alloying (MA) followed by spark plasma sintering (SPS). The main objective of this research is to consolidate Ni-Ti-C MMCs with varying C/Ti ratio and characterize the MMCs to investigate

ABSTRACT Friction and wear are the primary factors for the failure of liner, which affects the lifting capacity and the milling cost in ball mills. But there are not effective methods to measure and evaluate the friction and wear behaviour of liner. Therefore, it is vital to understand the friction and wear mechanisms of liner in ball mills. In this paper, the multi-body friction and wear properties

Abstract Disc brakes are widely used in various kinds of light vehicles. Currently, it has become a tendency to reduce mass and volume of the brake systems because of the increasing lightweight requirement for vehicles, especially for passenger vehicles in the populated cities and outdoor sport. However, there is often conflict between lightweight and reliability. In this paper, braking characteristics

Abstract The wear characteristics and related mechanisms of the ring chain of a scraper chain were investigated. Multiple sets of wear tests were performed in order to simulate the working environment of the heavy-load scraper conveyor. The wear characteristics of the ring chain in different environmental media (acid, alkaline, neutral electrolyte solution, deionized water and pulverized coal mixture)

The objectives of this investigation were to experimentally and analytically investigate the dynamics of a medium sized, relatively high speed ball bearing supported turbocharger (TC). In order to achieve the objectives a TC test rig was designed, developed and instrumented with a combination of strain gauge based load sensors and proximity probes. The sensors were used to measure the axial and frictional

A mixture model suitable for thermal effect on EHL of emulsions is proposed. The maximum temperature rise occurs at the emulsion layer because sliding occurs mainly in the emulsion layer to generate shear heating, and it increases with increasing oil concentration, slide-to-roll ratio, mean speed and load. The rise in surface temperature of the rollers decreases with the increase in the adsorbed layer’s

Abstract In this work, a systematic investigation was carried out to study the electrochemical and tribocorrosion behavior of LY12 aluminum alloy sliding against an Al2O3 pin in artificial seawater, using a pin-on-disc tribometer combined with an in situ electrochemical workstation. The results revealed that the cathodic shift of open circuit potential and two order of magnitude increase in current