Friction Coefficient Resistance Research Articles

Friction and abrasive wear behaviour of Al 2 O 3 -13TiO 2 and Al 2 O 3 -13TiO 2 +Ni Graphite coatings

Abstract The friction and abrasive wear of plasma sprayed Al2O3-13TiO2 coating, with and without the addition of graphite was investigated. XPS analysis was used to determine the extent of γ-α Al2O3 phase transformation after wear. γ-α Al2O3 phase transformation had different influence on friction and wear of coatings. Al2O3-13TiO2+15% Ni Graphite coating exhibited lower coefficient of friction and lower abrasive wear rates than Al2O3-13TiO2 coating; the magnitude of decrease was dependent on load. The better abrasive wear resistance and lower coefficient of friction of Al2O3-13TiO2+15% Ni Graphite coating was due to the synergistic effect of self-lubricating film of graphite and tribochemical reactions. The severity of contact could identify transitions in abrasive wear rates, operating wear mechanisms and associated failure modes.

A statistical prediction on wear and friction behavior of ZrC nano particles reinforced with Al[sbnd]Si composites using full factorial design

This paper investigates the dry sliding wear and friction behavior of pure Aluminium (Al), Al12 Si with its reinforcement ZrC in various weight percentages. The samples were prepared by Powder Metallurgy method. The wear test was conducted using the pin-on-disc, with the varying the parameters of normal load (10–40 N), sliding distance (500–2000 m) and constant sliding velocity of 2.618 m/s. The ZrC reinforced specimens showed the lower coefficient of friction and maximum wear resistance. The influence and percentage contribution of variable parameters were analyzed using Minitab 17.3.1 software. The wear worn surface of the hybrid composites was analyzed using Scanning Electron Microscope and reveals that Al12Si shows fracture and deformed whereas Al12Si15ZrC consists of fine and coarse powders with uniform distribution and there is very less wear debris are seen. Al12Si15ZrC shows reduced coefficient of friction and specific wear rate while the load and sliding distances increases with increase in wt.% of carbide reinforcement.

High‐Energy Impact Behaviors of Hybrid Composite Plates Strengthened with 3D‐UHMWPE Composites

This study deals with drop‐impact effects of new hybrid concrete plates strengthened with an ultrahigh molecular weight polyethylene (UHMWPE). The proposed 3D‐UHMWPE results in excellent mechanical properties such as high abrasion resistance, impact strength, and low coefficient of friction. These special properties allow the product to be used in several high‐performance applications. In this study, we used two kinds of high‐performance materials for the impact reinforcement of a structure made of conventional materials such as a concrete. In particular, the impact mechanism of a fiber‐concrete hybrid structure was studied using various parameters. The parametric studies are focused on the various effects of drop‐impact on the structural performance. The combined effects of using different fiber‐reinforced materials on the impact behavers are also investigated.

Pentamaran configuration design with modeling hull form for resistance minimization

Multi-hull ship had characteristics with complex geometry configurations. In the early stage design, multi-hull ship with proper configurations can be producing both minimum resistance and power consumption. Increasing number of hull as in pentamaran will increase frictional resistance, but total resistance can be reducing by decreasing wave making resistance with a slender hull form. With CFD tool used to examine minimum resistance with modified modelling of chine hull form on variation i.e. deadrise angles, waterline section of entrance angle and longitudinal section of stem angle. All simulations were conducted with fix separation on S/L 3/16 and Froude number up to 0.7. Comparison with the original hull form, chine hull form C35 II in deadrise 35° and angle of entrance 15° more advantageous with maximum resistance drag reduction 20.38%. The results of the study had been displayed in table and charts of chine pentamaran which having the smallest total resistance expressed in coefficient of friction and wave resistance.

Wear behaviors of TiN/TiCN/DLC composite coatings in different environments

Diamond like carbon (DLC) coatings have high wear resistance and low coefficient of friction and its features are being tried to be further developed. We deposited TiN/TiCN/DLC composite coatings on inconel substrates with closed field unbalanced magnetron sputtering system to improve the features of the conventional DLC coatings. Structural, chemical and bond types of the coating were obtained with the XRD, SEM, EDS and XPS analyses. Wear behaviors of the coatings were determined in atmosphere, distillated water and commercial oil conditions under low (2N) and high (10N) constant load values with using pin-on-disc tribo-test system. The wear results demonstrated that using the TiN/TiCN layers with the DLC coatings increased the load carrying capacity, decreased the CoF, and wear rates at the high load values.

Surface damage mitigation of TC4 alloy via micro arc oxidation for oil and gas exploitation application: Characterizations of microstructure and evaluations on surface performance

Because of its excellent corrosion resistance, high specific strength and high tensile strength, TC4 titanium alloys used as petroleum tubes have received wide interest from material engineers after many technical investigations and estimations. However, because of its low surface hardness values, high coefficient of friction and poor wear resistance, the TC4 alloy is seldom adopted in tribological-related engineering components. In this work, micro-arc oxidation (MAO) coatings were fabricated on TC4 alloys in NaAlO2 and (NaPO3)6 electrolytes with and without ultrasonic assistance. The microstructural characterizations of the produced MAO coatings were investigated. Comparative estimations of electrochemical corrosion in CO2-saturated simulated oilfield brine and tribological behaviours on MAO coatings and TC4 alloys were conducted. The results showed that the introduction of ultrasound increased the thickness of the MAO coatings. The thickness increased by 34% and 15% in the NaAlO2 and (NaPO3)6 electrolytes, respectively. There was no significant discrepancy in phase constitutions when the MAO processes were conducted with and without ultrasonic assistance. Both MAO coatings obtained with and without ultrasonic assistance were found to improve the corrosion and wear resistance of the TC4 alloy. MAO treatments made it possible to ensure the working surface of a TC4 alloy with an enhanced surface performance for oil and gas exploitation applications.

An investigation on the effect of surface treatment of bamboo fiber-filled PMMA composite

Polymeric composites have steadily gained importance in recent years for industrial applications. The increase in use calls for a better understanding of their behavior under different working environments. Friction and wear are considered two important parameters that govern tribological behavior. In this study, the friction and wear characteristics of bamboo fiber-Polymethyl methacrylate (PMMA) and MoS2 filler in PMMA composites were experimentally investigated at varied loads and sliding velocities. From this investigation, it was found that the addition of MoS2 in PMMA composite system showed least coefficient of friction and highest wear resistance.

Experimental study on thermo-hydraulic performances of TiO2-H2O nanofluids in a horizontal elliptical tube

Stable TiO2-water nanofluids are prepared by a two-step method, and the morphologies of nanoparticles and the stability of nanofluids are investigated. The heat transfer and flow characteristics of nanofluids flowing through a horizontal circular tube and a horizontal elliptical tube are experimentally investigated. The effects of nanoparticle mass fractions (φ = 0.1 wt%, φ = 0.3 wt%, φ = 0.5 wt%) and Reynolds numbers (Re=5000-15,275) on the Nusselt number and flow frictional resistance coefficient are discussed. In addition, computational formulas for heat transfer and flow performances are put forward based on the experimental data using the polynomial fit technique. Also, thermo-hydraulic comprehensive performances of nanofluids in the horizontal circular tube and the horizontal elliptical tube are studied.

Tribological Characteristics of Silicon Carbide – Epoxy Nanocomposites

The applications of polymer nanocomposites have been increased in fast, in technological applications and engineering materials for seal and sliding components in many machines, devices, tools and variance vehicles. In this research friction and wear coefficients of epoxy reinforced by nanoparticles silicon carbide in terms of variance volume fractions have been tested. Mechanical – layup method with ultrasonic technique for the dispersion of the nanoparticles within the polymer matrix are used. Wear and friction coefficient tests are created out using pin -on-disc technique. The results showed significant improvement in wear resistance and low coefficient of friction for 10 vol. % nanocomposites compared with the matrix alone. It can be concluded from scanning electron microscopy (SEM) results before and after the tests that the wear was transformed from the severe to the moderate.

Laser processed calcium phosphate reinforced CoCrMo for load-bearing applications: Processing and wear induced damage evaluation.

Co-based alloys, an ideal choice for biomedical load-bearing implants, show low wear rates along with low coefficient of friction (COF) and good resistance to corrosive media. However, significant material loss can occur in vivo due to wear and/or corrosion of CoCrMo over long periods of time. Release of metal ions in the human body over time leads to medical complications such as metallosis, which can often require a revision surgery that can adversely affect the quality of life for the patient. We hypothesize that metal ion release from CoCrMo alloys can be reduced during articulation using an in situ formed inorganic tribofilm, and our results validate our hypothesis in calcium phosphate reinforced CoCrMo composites.

Computational Fluid Dynamics Study of the Dead Water Problem

The dead water problem, in which under certain conditions a vessel advancing in a stratified fluid experiences a considerable increase in resistance respect to the equivalent case without stratification, was studied using computational fluid dynamics (CFD). The advance of a vessel in presence of a density interface (pycnocline) results in the generation of an internal wave that in the most adverse conditions can increase the total resistance coefficient by almost an order of magnitude. This paper analyses the effects of stratification on total and friction resistance, the near field wake, internal and free surface waves, and resistance dynamics. Some of these effects are reported for the first time, as limitations of previous efforts using potential flow are overcome by the use of a viscous, free surface CFD solver. A range of densimetric Froude numbers from subcritical to supercritical are evaluated changing both the ship speed and pycnocline depth, using as platform the research vessel athena. It was found that the presence of the internal wave causes a favorable pressure gradient, acceleration of the flow in the downstream of the hull, resulting in thinning of the boundary layer and increases of the friction resistance coefficient of up to 30%. The total resistance presents an unstable region that results in a hysteretic behavior, though the characteristic time to establish the speed–resistance curve, dominated by the formation of the internal waves, is very long and unlikely to cause problems in modern ship speed controllers.

On the recyclability of polyamide for sustainable composite structures in civil engineering

Previous studies have highlighted the potential application of Polyamide 6 (PA6) as excellent recyclable polymeric material, which is well suited to form carbon-fiber-reinforced, graphene-nanoplatelets-reinforced or metal-porous-polymer composite structures. The conventional screw extrusion process is one of the established melt processing techniques, having potential of enhancing mechanical, thermal and morphological properties of polymeric materials. PA6 is an important engineering material which exhibits excellent mechanical properties, chemical resistance, wear resistance, dimensional stability, and low coefficient of friction. In the present study attempts have been made to explore the behavior and characteristics of the recycled PA6 polymer through twin screw extrusion process towards increase in recyclability (as primary recycling process). The mechanical properties (tensile strength, Young’s modulus, peak load), metallurgical properties (porosity, wear and material loss) supported with optical microscopy were investigated to ensure the recyclability of PA6 as a properties enhancing extrusion process. It has been observed in the present study that, melt processing by screw extrusion at best settings of input process parameters enhances the material properties for applications in sustainable civil engineering.

Structure and properties of NbN/MoN nano-multilayer coatings deposited by magnetron sputtering

NbN/MoN nano-multilayer coatings with MoN layer thickness ranging from 1.0 to 4.3 nm were deposited using a closed field unbalanced magnetron sputtering system by varying Mo target current. The structure of the coatings was investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. The mechanical and tribological properties of the coatings were evaluated by nano-indentation and ball-on-disc wear tests. It was found that all of the as-deposited NbN/MoN multilayer coatings exhibit fcc B1-NaCl structure and the preferred orientation of the coatings changed from (111) to (200) as MoN layer thickness exceeds 2.1 nm. The NbN/MoN multilayer coatings with MoN layer thickness 1.0 nm exhibit a superhardness with value of 40.0 GPa. Further increase of MoN layer thickness results in a decrease in coating hardness. The NbN/MoN multilayer coatings exhibit lower coefficient of friction and better wear resistance compared to NbN single layer coatings. A low COF of 0.53 and wear rate of 0.7 × 10−6 mm3/Nm can be achieved in the NbN/MoN multilayer coatings with a MoN layer thickness of 4.3 nm.

Evaluation of niobium carbide coatings produced on AISI L2 steel via thermo-reactive diffusion technique

Thermo-reactive diffusion (TRD) is a high-temperature process for producing hard metal carbide coatings on carbon-containing substrates. In this study, niobium carbide (NbC) coatings were produced on low-alloy special-purpose tool steel (AISI L2) via a thermo-reactive powder-pack treatment. The treatment was done in a sealed box with a powder mixture consisted of ferroniobium, ammonium chloride and alumina powders at different times and temperatures. The ratio of the powders was optimized based on the thickness of coatings. The presence of NbC was confirmed by XRD and the growth kinetics of the coatings was studied, as well; leading to an empirical equation to estimate the thickness of coating based on treatment time and temperature. Moreover, pin-on-disc wear tests were conducted on the coatings at various applied loads. The results showed a significantly higher wear resistance and lower coefficient of friction for the coated metal compared to the bare metal.

One-step hydrothermal synthesis of reduced graphene oxide/zinc sulfide hybrids for enhanced tribological properties of epoxy coatings

Advanced reduced graphene oxide/ZnS (RGO/ZnS) hybrids were synthesized via a facile and effective hydrothermal method to enhance the tribological properties of epoxy coatings. Physical characterization of the hybrids indicated that the as-prepared products had the high chemical purity and that the ZnS nanoparticles combined well with RGO nanosheets. Meanwhile, ZnS nanoparticles were uniformly dispersed on RGO nanosheets with the diameters of several decade nanometers. The tribological properties of ZnS, RGO, and RGO/ZnS with epoxy coating were systematically investigated. By comparing the result of tribological study, it was found that RGO/ZnS hybrids had better lubricating properties with lower coefficient of friction and higher wear resistance than those of ZnS or RGO. In addition, the test results indicated that RGO/ZnS hybrids showed good stability with increased in applied load. These excellent tribological properties of RGO/ZnS hybrids were attributed to the excellent synergistic effects between ZnS nanoparticles and RGO nanosheets and to the transfer film that formed on the steel ball. This work paved a way to expand the potential applications of nanoparticles in the tribological field.

Plasma electrolytic oxidation coatings on AZ31 magnesium alloys with Si3N4 nanoparticle additives

Magnesium AZ31 alloys have been widely used in the aerospace, automotive, and personal computer industries due to their light weight and low density. However, high chemical reactivity, poor corrosion and wear resistance limit their further use in many other fields. The plasma electrolytic oxidation (PEO) process can produce a protective oxide layer on the Mg alloy to improve its mechanical property, wear resistance, and corrosion resistance. In this work, silicon nitride (Si3N4) nanoparticles were added into the reaction electrolyte to study their influence on the microstructure, mechanical, and anticorrosion properties of PEO coatings on AZ31 Mg alloy. The breakdown voltage for igniting the plasma discharge decreased with increasing concentration of Si3N4 nanoparticles. The PEO coating without Si3N4 additives in the reaction electrolyte had mainly MgAl2O4 and minor MgO phases. On the other hand, when Si3N4 nanoparticles were included in the PEO reaction, a Mg2SiO4 phase is present. In general, the coating thickness, surface roughness, hardness and elastic modulus increased with increasing Si3N4 nanoparticle concentration up to 3g/L. A maximum hardness of 16.4GPa was found in the coating fabricated with 3g/L Si3N4 nanoparticles added. The PEO coating fabricated using 2g/L of Si3N4 nanoparticles in its electrolyte exhibited the best corrosion resistance, high hardness, good adhesion, and low coefficient of friction in this study.

Investigate the Friction and wear behavior of MoS2 nanoparticles in solid state lubrication

A solid-state lubricant powders is one of the most significant powders usedto protect surfaces from damage in cases of relative motion, with a reduction in thefriction and wear between them. In this study, molybdenum disulfide (MoS2),purity 99%, nanoparticles have been used as solid-state lubrication, due to it havinga low coefficient of friction and high wear resistance. In which MoS2 particles havebeen distributed with 1.69 x 1015 particles per m2 over the steel disc’s surfaceagainst the steel pin using a pin on disc tribometer machine. The pin on disctechnique was used to study the friction coefficient behaviour of the MoS2distribution particles and the position depth of the steel pin on the steel disc surfacewhen the ambient environment was air and humidity. It was used to examine thetribological behaviour of the steel pin on the steel disc surface with no distributionof MoS2 nanoparticles and also for a steel pin on steel disc with a distribution ofMoS2 nanoparticles. Then, the morphologies and microstructures of thedistributions of MoS2 nanoparticles were characterized using Scanning ElectronMicroscopy (SEM). In a result, the distribution of MoS2 nanoparticles have resultedin a lower friction coefficient and higher wear resistance compared with only steelpin on steel disc surfaces.

THE EFFECT OF THE COEFFICIENT OF FRICTION ON THE BIOMECHANICS OF CONTACT IN HIP ENDOPROSTHESIS

Hip replacement surgery, by introducing a specific replacement head on the stem and cup, completely changes the conditions of co-operation typical for the biological correct pair. The clinical selection of endoprosthesis, apart from other conditionings, involves a dilemma between the choice of a rigid tribological node and the selection of a susceptible bearing cushioning the locomotive loads. The aim of the study is to evaluate the coefficient of friction and wear resistance of materials used for sliding contact in the endoprostheses of hip joints. On the basis of the conducted tests, it can be stated that, in the selection of material for cups of endoprosthesis, the wear resistance is important, and the coefficient of friction in contact head and cup in the prosthesis is less important. The presence of significant disproportions between the two parameters of the tribological process proves that the biomaterial is less useful on the cup. In the assessment of cooperation in the endoprosthesis, simulations of the contact of structural elements are useful, because, on that basis, in the correlation with tribological parameters, one can make conclusions about the distribution of stresses and displacements that may determine the lifetime of the implant.

ВИБРОАКУСТИЧЕСКИЕ ИСПЫТАНИЯ ОБРАЗЦОВ ТРИБОСОПРЯЖЕНИЙ НА ИЗНОСОСТОЙКОСТЬ

For the development of standards of timing and amount of shipboard equipment maintenance and repair it is important to study and improve the theory and practice of evaluation of endurance of such friction pairs as sliding bearings. In the diagnosis of rolling bearings vibroacoustic methods are widely used, but, as for sliding bearings, these methods are still at the stage of research with respect to friction. Thereby, the results of testing different types of tribounit samples on friction test machines have been studied. There have been done vibration measurements for given conditions (rotation speed and load), where the root mean square values (RMS) of vibrational acceleration a in m/s2 or dB for acceleration were used as main diagnostic parameters. The authors have investigated dependencies of vibration levels for each band of tri-band spectrum on rotational speed, load, lubrication, surface roughness with respect to temperature, coefficient of friction and wear resistance. It has been proved that the source of VHF vibration of RMS is friction in coupling, depending on the surface condition and lubrication type of the friction pair. Dependency of acceleration RMS level on rotational speed and load of the sample has been stated. The results allow to infer about the effectiveness of the proposed tri-band vibroacoustic characteristics of the tribounits using vibrometer CM-21. This method can be used for diagnostics of sliding bearings, which can require standardization of modes and conditions of measurement and the establishment of zones of maximum permitted levels of the object state.

Effect of MoS2 on the tribological properties of carbon fabric composites under wet conditions

Carbon fabric reinforced phenolic composites are very attractive for use as friction materials under wet conditions due to their excellent self-lubricity, wear resistance, and high mechanical strength. However, brittle fracture of carbon fabric bundles during friction is one of the major problems that limit their application. In this work, MoS2 particles were used as additives and friction modifiers to improve the wear and friction behaviors. The composites containing different amounts of MoS2 particulates (0–20 wt%) were fabricated by impregnation technique. The influence of MoS2 on the tribological properties under oil-lubricated conditions has been studied systematically. The experimental results revealed that tribological characteristics such as coefficient of friction and wear resistance were changed significantly with the relative amount of MoS2. Addition of MoS2 within 15 wt% was found to decrease the wear rates of the composites, while 20 wt% MoS2-filled composites exhibited highest wear rate compared to other test samples. Increasing MoS2 content resulted in a rise in the wear rate of the counterparts. Wear mechanisms had been investigated by scanning electron microscope, which could support the observed wear performance.