Tribological Properties Of Friction Pairs Research Articles

Tribological properties of friction pairs under double composite surface configuration with diamond film and laser texture

A composite model, which combined diamond thin film with surface microstructure, was designed on the surface of silicon carbide by picosecond laser and hot filament chemical vapor deposition. And the multifunctional friction and wear tester was used to study the tribological performance of the friction pair (silicon carbide-graphite) under oil-poor conditions to examine the tribological performance of the friction pair in terms of surface temperature rise and time-varying wear. The results show that the friction coefficient under the composite modeling of surface microstructure and diamond film reaches 0.009, and at the same time, the surface temperature of the composite modeling is only 61.2 ℃, which is 5.1% lower than that of only diamond film and 62.1% lower than that of no surface treatment, which indicates that the high frictional heat has caused a significant graphitization transition in the film. And the surface of the friction sub-surface with the lowest temperature (surface microstructure and diamond thin film composite modeling) kept the carbon content at more than 90% without the formation of Si-C bonding, which guaranteed the complete carbon friction transfer film; At the same time, the ID/IG ratio of the friction surface under the composite modeling of the surface microstructure and diamond film is about 0.06 at the abrasion mark, the ID/IG ratio of the diamond film only is about 0.33, and the ID/IG ratio of the friction surface without any surface treatment is about 1.37. Transient high temperatures lead to abrasion and localized spalling on the surface of friction pairs, causing graphite oxidation to become progressively more severe, thus transforming abrasive wear into adhesive wear. As a result, double composite surface configuration with diamond film and laser texture further reduced the transient temperature rise of the surface and improved the tribological performance of the friction pairs.

The impact of additives applied to the lubricant on the burnishing process and tribological properties

The aim of this study was to determine the impact of additions of tungsten carbide and silicon carbide microparticles to the lubricant used in the burnishing process on the tribological properties of friction pairs. The cylinders made of AISI 1045 steel constituted a workpiece. Burnishing was made with a lubricant the SN150 base oil with addition of tungsten carbide and silicon carbide microparticles. The tested materials were burnished with forces of 1000 N and 1500 N. Before and after the burnishing process, the surface roughness and hardness of the tested materials were measured. The study also presents the results of tribological properties of friction pairs with the tested structural materials. It was found that the addition of tungsten carbide microparticles to the base oil in the burnishing process can result in improved surface quality and reduced surface roughness. The results also confirmed the effect of addition of tungsten carbide and silicon carbide to the lubricant used in the burnishing process on tribological properties.

Sliding bearings with lead-bismuth liquid metal lubrication

The article presents the results of tribological tests of a thrust bearing made of steel-bronze materials when lubricated with a lead-bismuth metal melt under conditions of heating up to 500°C. The influence of steel-bronze on the coefficient of friction in the ranges of load 0.17–1.0 MPa, velocity 0.05–0.23 m/s, and temperature 250–500°C was studied. It has been established that the tribological properties of friction pairs under experimental conditions mainly depend on temperature, which determines the wetting angle and the viscosity of the metal melt. With an increase in the temperature of the melt above 300°C, the viscosity of the melt decreases, and the liquid metal lubricant is squeezed out of the actual contact areas.

Study on antifriction mechanism of surface textured elliptical bearings

Abstract The surface micro texture can improve the surface tribological properties of friction pairs. As a two oil wedge bearing, elliptical bearing can restrain the journal whirl and maintain the stable operation. In the manuscript, the surface micro-texture is combined with elliptical bearing, and the influence of micro-texture shape, micro-texture depth and micro-texture radius on oil film pressure, bearing capacity and friction coefficient of elliptical bearing is studied by theoretical calculation and experimental research. The results show that with the increase of micro-texture depth, the bearing capacity first increases and then decreases; and when the dimensionless texture depth is 0.03, the bearing friction is the lowest and the bearing capacity is the highest. When the dimensionless radius of the micro texture is v3, the lubrication performance of the bearing is the best. When the shape of micro-texture is circle or triangular, the lubrication performance of elliptical bearing can be improved.

Reactive magnetron sputtering of TiN-Pb coatings using two metal targets

One of the promising areas of application of the magnetron co-sputtering method using two separate targets in a reactive atmosphere is to increase the tribological properties of friction pairs by applying composite solid lubricant coatings consisting of a solid matrix and a soft lubricant. In this paper, we study the dependence of the parameters of TiN-Pb coatings obtained by co-spraying of separate Ti and Pb targets in a mixture of Ar and N gases on pressure. The factors that have a significant impact on the process of coating deposition were also determined.

Tribological Properties of Friction Pair between 316L Stainless Steel and CF/PEEK with Nonsmooth Surface under Seawater Lubrication

This work improves the tribological behavior via innovative surface designs for slipper pairs in seawater axial piston pumps. 316L stainless steel and carbon fiber/polyether ether ketone (CF/PEEK) were selected as friction pair matching materials due to their good corrosion resistance, self-lubrication, and wear resistance. One type of smooth surface and five different types of pit nonsmooth surfaces were created on CF/PEEK specimens. Rotational sliding tests were performed on a friction and wear tester at a load of 200 N at five different sliding speeds (0.79, 1.18, 1.57, 1.96, and 2.36 m/s) under seawater lubrication. The experimental results indicate that the friction process of the smooth surface friction pair is mainly based on abrasive wear and adhesive wear. The friction coefficient range is 0.05–0.08, the specimen contact temperature is 38–75 °C, and the wear rates of 316L and CF/PEEK are 2.3 × 10−5 to 1.2 × 10−4 mm3/(MPa·m) and 5.6 × 10−4 to 7.6 × 10−3 mm3/(MPa·m), respectively. Pits on the specimen surface produce a hydrodynamic effect and store wear debris. The friction process of the nonsmooth surface friction pair is mainly controlled by a ploughing mechanism with only a slight amount of adhesive wear. The friction coefficient range is decreased to 0.03–0.07, the specimen contact temperature is decreased to 28–54 °C, and the wear rates of 316L and CF/PEEK are decreased to 1.2 × 10−5 to 9.1 × 10−5 mm3/(MPa·m) and 2.6 × 10−3 to 7.1 × 10−3 mm3/(MPa·m), respectively. The geometrical arrangement of the elliptical and tri-prism pits increases the convergence gap range and produces a higher bearing capacity. As the sliding speed increases, the friction coefficient first decreases and subsequently slightly increases, the specimen contact temperature increases, and the wear rate decreases.

Research on the influence of micropits structure on the tribological performance of friction pairs

According to the traditional lubrication theory, the smoother the friction pairs the better the friction performance. But in recent years, a large number of theoretical and experimental results have shown that the friction surface with microstructure can effectively improve the tribological performance of friction pairs. For smooth surface and micro-dimple surface with different shapes of friction pairs, the two-dimensional finite element model is established based on the Navier–Stokes calculation equation of the fluid, and the effect of hydrodynamic effects arising from micro-dimple structure with different shapes on friction performance of friction pairs is analyzed. Through friction and wear testing, the friction properties of smooth surface and micro-dimple surface friction pairs are compared and analyzed. Theoretical simulation and experimental verification show that the surface of friction pairs with micropits can obviously improve the lubrication conditions of friction pairs and effectively improve the tribological properties of friction pairs.

Influence of amorphous carbon layers on tribological properties of polyetheretherketone composite in contact with nitrided layer produced on Ti6Al4V titanium alloy

The key issue in bone implants biomechanics is – besides using biocompatible materials - the optimization of tribological properties of friction pairs occurring in joint implants e.g. knee and hip endoprothesis. Increasingly important role in these systems, alongside ceramics-on-ceramics and metal-on-metal, have metal-on-polymer friction pairs. Commonly used in orthopedics ultra-high molecular weight polyethylene (UHMWPE) does not meet the requirements of modern bone implants, mainly because of its harmful wear products which can cause inflammation and osteolysis of surrounding tissues after several years of using the endoprosthesis. Therefore, other polymer materials have been developed to replace UHMWPE, as well as several surface engineering methods are used for enhancing biocompatibility and tribological properties of applied materials. One of the materials to replace UHMWPE is increasingly used in medicine polyetheretherketone (PEEK) – a polymer material with a high biological indifference and mechanical properties.The article presents characteristics of TiN+Ti2N+αTi(N) nitrided layer produced on Ti6Al4V titanium alloy using glow discharge assisted nitriding process at the plasma potential, also known as the active screen plasma nitriding process and hydrogenated amorphous carbon doped with nitrogen layer a-C:N:H produced via RFCVD process on PEEK-based composite consisting of 10% graphite, 10% carbon fibers and 10% PTFE. Tribological properties of a-C:N:H – TiN+Ti2N+αTi(N) friction pair using “ball-on-disc” and “block-on-roll” tests were examined in correlation with microstructure (TEM, SEM, Raman spectroscopy) and surface morphology and topography (SEM, AFM, optical profilometer).The goal of this work is to present a new possibility of material solution for a ‘head-acetabulum’ friction pair in hip joint endoprosthesis using PEEK (PEEK T) as a replacement for commonly used UHMWPE and nitrided layer produced on Ti6Al4V titanium alloy using active screen plasma nitriding process.Amorphous carbon layer, 200nm thick, produced on PEEK composite significantly improved tribological properties of PEEK composite – TiN (nanocrystalline)+Ti2N+αTi(N) layer friction pair, decreasing the friction coefficient by 2 times and minimizing wear of both used materials in the point contact (“ball-on-disc” method) and in surface contact (“block-on-roll” method).

Tribological Properties of Friction Pairs in Lubricant Contaminated with Particles under High Temperature

ABSTRACTA liquid–solid lubricant with sand particles of different sizes and concentrations is prepared in advance. The viscosity of the lubricant is measured by a capillary viscometer to determine its relationship to the concentration or size of the sand particles. The relationships between friction and concentration or size of the sand particles are also identified with a UMT2 tribometer. Results indicate that the size of sand particles plays an important role in the lubrication performance; when the size of sand particles is 1–5 μm, the friction coefficient of the liquid–solid lubricant is reduced at low concentration and low load. Contaminant concentration greatly influences the tribological behavior of such a lubricant. The failure probability of the part surface decreases with a reduction in particle concentration; moreover, a high temperature aggravates the friction and wear of this surface. The friction coefficient is 0.14 at 200°C, which is well above the friction coefficient at room temperature (0.078), and the wear volume also increases by 30% compared to the normal temperature. When the temperature is 300°C the wear volume is two times that under room temperature.

Tribological Properties of Laser Microtextured Surface Bonded With Composite Solid Lubricant at High Temperature.

A combination technology of the solid lubricant and the laser surface texturing (LST) can significantly improve the tribological properties of friction pairs. The plate sample was textured by fiber laser and composite lubricant of polyimide (PI) and molybdenum disulfide (MoS2) powders were filled in the microdimples. Sliding friction performances of micron-sized composite lubricant and nano-sized composite lubricant were investigated by ring-plate tribometer at temperatures ranging from room temperature (RT) to 400 °C. On the one hand, the results of the micron-sized composite lubricant show that the friction coefficient of the textured surface filled with composite lubricant (TS) exhibits the lowest level and the highest stability compared to a textured surface without solid lubrication, smooth surface without lubrication, smooth surface burnished with a layer of composite solid lubricant. The better dimple density range is 35-46%. The friction coefficients of the sample surface filled with micron-composite solid lubricant with the texture density of 35% are maintained at a low level (about 0.1) at temperatures ranging from RT to 300 °C. On the other hand, the results of the nano-sized composite lubricant show that these friction properties are better than those of MoS2-PI micron-sized composite. The friction coefficients of MoS2-PI-CNTs nano-sized composite solid lubricant are lower than those of the MoS2-PI composite lubricant at temperatures ranging from RT to 400 °C. In addition, the possible mechanisms involving the synergetic effect of the surface texture and the solid lubricant are discussed in the present work.

Evaluation of tribological properties on PEEK + CA30 sliding against 17-4PH for water hydraulic axial piston motor

Water hydraulic axial piston motor (WHAPM) is one of the key components in water hydraulic system. It is essential to identify the desired engineering materials and material combinations for improving the WHAPM, which are featured by strong wear and erosion resistance. As the candidate materials of friction pairs in WHAPM, the tribological characteristics of 30 wt% carbon fiber-reinforced PEEK (PEEK + CA30) sliding against 17-4PH precipitation-hardening stainless steel under fresh water lubrication were investigated. The friction experiments were conducted on MCF-10 ring-on-ring test rig. With the help of metallographic microscope, an attempt was made to approach the tribological properties of friction pair. The experimental results showed that the ideal sliding velocity is also about 1 m/s when the applied load is between 200 and 600 N. It can be concluded that the slipper designed based on the principle of residual pressure coefficient bearing with auxiliary supporting area is an effective way to decrease the actual pv value in the prototype of WHAPM. The research outcomes will lay the foundation for the design of key friction pairs in the water hydraulic components and system.

Effect of the composition of mineral and organomineral mixtures on the tribological properties of friction pairs

We have studied the tribological properties of friction pairs of chromium-plated steel parts after processing with geomaterials: serpentinite, a natural silicate, a mixture of serpentinite and the silicate, a polysaccharide-modified natural silicate, and a mixture of serpentine and the polysaccharide-modified silicate. The abrasive used was quartz dust ranging in particle size from 1 to 5 μm, whose concentration reached 1%. The mixtures were shown to be highly effective in producing composite coatings on friction surfaces of parts. The incorporation of the polysaccharide-modified silicate into a friction joint considerably reduces its coefficient of friction and, as a consequence, the energy level of contact interaction.

Tribological properties of crown‐type phosphate ionic liquids as lubricating additives in rapeseed oils

ABSTRACTThe friction and wear properties of rapeseed oils with different concentrations and crown‐type phosphate ionic liquids were studied by an Optimol SRV oscillating friction and wear tester. Crown‐type phosphate ionic liquids have better solubility than conventional ionic liquids in rapeseed oils. The tribological test results showed that the crown‐type phosphate ionic liquids as lubricating additives in rapeseed oil exhibited better tribological performance than the base oil for steel/steel friction pair under various loads. It is noted that the friction pair showed the least friction coefficient and wear volume when the concentration of ionic liquids was 1 wt.%. The better tribological properties of friction pair should be attributed to the effective boundary films formed in the worn surface, on various tribochemical products, organometallic products and iron oxides. Copyright © 2012 John Wiley & Sons, Ltd.

The Use of STM for Investigation of Surface Relief in Respect to Tribologic Properties of DLC Coatings

The surface relief is one of the main factors defining the tribological properties of friction pairs, especially in the case of diamond and diamond like carbon (DLC) coatings. Even such thin as 10 - 100 nm coating can considerably increase the wear resistance and drastically reduce the friction coefficient of friction pairs. The most convenient techniques for investigation microrelief effect on tribologic properties of thin films seems to be the scanning tunneling microscopy (STM). The microrelief was changed by surface bombardment with 1 keV ions of O, At and N. The friction coefficients was found to depend upon ion bombardment time and the minimal value could be achieved. The STM studies showed that namely at this time the surface relief was the most smooth. For the coatings in the initial state the surface relief was about 15 - 20 nm and in the state with minimal friction coefficient - about 1.5 - 3 nm.