Improvement Of Tribological Properties Research Articles

Hard carbon coatings antifriction properties improvement by alloying

The efficiency of hard carbon coatings with different structure to improve the tribological performance of contacting surfaces of machine parts working in heavily loaded conditions has been analyzed. The possibility of increasing the antifriction and wear-resistant characteristics of these coatings by doping them with metals of the chromium subgroup of the Periodic table has been demonstrated. The possible mechanisms of hard carbon coatings dry and boundary friction tribological properties improvement by alloying have been considered. The possible role of alloying elements choice, structural and tribochemical factors has been discussed.

Improvement in Tribological Properties of Cr12MoV Cold Work Die Steel by HVOF Sprayed WC-CoCr Cermet Coatings

The main objective of this study was to develop an efficient coating to increase the wear resistance of cold work die steel at different temperatures. The microstructures of high-velocity oxygen-fuel (HVOF)-sprayed WC-CoCr coatings were evaluated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of temperature on the tribological properties of the coatings and the reference Cr12MoV cold work die steel were both investigated by SEM, environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD), and a pin-on-disk high-temperature tribometer. The coating exhibited a significantly lower wear rate and superior resistance against sliding wear as compared to the die steel at each test temperature, whereas no major differences in terms of the variation tendency of the friction coefficient as a function of temperature were observed in both the coatings and the die steels. These can be attributed to the presence of nanocrystalline grains and the fcc-Co phase in the coating. Moreover, the wear mechanisms of the coatings and the die steels were compared and discussed. The coating presented herein provided a competitive approach to improve the sliding wear performance of cold work die steel.

An Experimental and Numerical Approach to Study the Performance of Modified Perforated Cutting Tools on Machining of Ti–6Al–4V Alloy

In this research, the main aim is to reduce the unfavorable effects that occurred during machining of the Ti–6Al–4V alloy by perforating the rake face and the flank face of the cutting insert. The main novelty in this research is that machining of Ti–6Al–4V alloy with the micro-hole textured insert helps in the improvement of tribological properties and also reduces cutting temperature at chip–tool interface with proper lubricating effect. To validate the micro-hole textured tools, it is compared with conventionally available insert. The deformation of Ti–6Al–4V alloy with modified cutting inserts was simulated, considering tool as rigid body and workpiece as elasto-plastic material. DEFORM 3D software was used for the simulation of the machining process with the updated Lagrangian formulation. To predict the cutting temperature and chip morphology, the thermo-mechanical analysis was applied using Johnson–Cook material model for the machining process. The turning of the Ti–6Al–4V alloy was carried out with the modified polycrystalline diamond (PCD) cutting inserts (Design 1 and Design 2) and commercially available PCD insert (normal insert). Coconut oil was used as a micro-pool lubricant during the machining process under minimum quantity lubrication environment. In the present work, the turning performance characteristics such as cutting temperature, cutting vibration, tool wear, chip morphology and surface integrity were measured during machining of the Ti–6Al–4V alloy. The experimental results of cutting temperature and chip morphology were validated with the simulation results with better accuracy. The machining results of Design 2 cutting insert showed maximum reduction of 30%, 38%, 45% and 35% in cutting temperature, cutting vibration, tool wear and surface roughness, respectively, when compared with machining under normal insert and Design 1 cutting insert. It is also evident from the results that machining with Design 2 cutting insert significantly improved the process performance of the product quality at higher feed rates.

Evaluation of mechanical and frictional properties of CuO added MgO/ZTA ceramics

The focus of the present work is to investigate the tribological effect of adding CuO as solid lubricant in MgO/ZTA (Magnesia-Zirconia Toughened Alumina) ceramics. Different wt% of CuO (0–5 wt%) have been added in MgO/ZTA ceramics using powder metallurgy process route to study the change in mechanical properties i.e., hardness, fracture toughness and flexural strength, as well as the tribological properties i.e., coefficient of friction (COF) and wear depth, against corundum alumina balls. The addition of CuO shows significant improvement in tribological properties but a diminishment of the mechanical properties. A significant reduction of 53.45% in COF with minimum wear depth is achieved with the addition of 1.5 wt% CuO inside the MgO/ZTA matrix. The improvement in COF and specific wear rate of the composite is observed with increasing sliding velocity due to the presence of uniform patchy layer along with a glossy surface on the wear track. The formation of patchy layer is enhanced with an increase in sliding velocity due to high squeezing and smearing of wear debris. A significant increment in specific wear rate is observed with increasing load due to the delamination process prevailing at the contact surfaces.

Improvement in Tribological Properties of Plasma-Sprayed Alumina Coating upon Carbon Nanotube Reinforcement

Crushed alumina powder heterocoagulated with 1 or 2 wt.% carbon nanotube (CNT) was used to produce plasma-sprayed coatings with improved tribological properties. Heterocoagulation is a colloidal processing technique, and it was used to produce a homogenous mixture of CNT in alumina. These coatings were compared with a pristine alumina coating using a pin-on-disk setup under various speed–load conditions. A 6-mm-diameter WC–Co ball was used as counterbody. The wear resistance of the coatings increased in the following order: pristine alumina, alumina with 1 wt.% CNT, and alumina with 2 wt.% CNT. Wear progressed by low cycle fatigue, microfracture, and finally pulverization of the already dislodged wear debris on repeated rubbing by the counterbody. The higher wear resistance of the reinforced coatings is attributed to their higher hardness and fracture toughness. The pristine alumina coating was found to crumble owing to diffuse intergranular fracture beneath the surface during rubbing under higher speed and load. Upon crumbling, the pulverized debris assumed a paste-like form and was ejected at the top under the compressive action exerted by the counterbody at its leading edge. The high wear of the pristine alumina coating is attributed to this effect.

Improvement of tribological properties of sintered self-lubricating composites produced by surface Mo-enrichment

In powder metallurgy, a high-cost method that is widely used to increase the useful life of the mechanical components is the addition of alloying elements. A less-exploited process is surface enrichment by plasma, where the same result is obtained only on the surface of the component at a rather lower cost. This paper reports on the improvement of the tribological properties of powder injection molding (PIM) self-lubricating composites produced by surface Mo-enrichment. The tribological properties were evaluated in terms of the scuffing resistance, friction coefficient, and wear rate values of enriched and non-enriched specimens, and counter-bodies. Scanning electron microscopy with energy dispersive X-ray spectroscopy and μRaman spectroscopy were used to characterize the wear scars. The results showed that Mo enrichment increased the scuffing resistance by an impressive 2000%, with a 90% decrease in the wear rate of the specimens and counter-bodies. These results were ascribed to several factors, including the microstructural modification, hardness increase, and tribolayer formation.

Study of the lubricating properties of hybrid liquid paraffin with TiO2 and CuO as nano-additives for engine oil application

Mineral based paraffin oil (L14480) lubricant finds it difficult to give optimum characteristics for modern engine application. In this work, possibility of hybrid paraffin oil which consists of paraffin oil (PO) and sesame oil (SESO) in equal proportions to be used for engine oil application is investigated. Properties of hybrid paraffin oil and SAE 20W40 were estimated and compared. Estimation of thermal characteristics of hybrid paraffin oil shows it have comparable properties with SAE 20W40. Low viscosity characteristics of hybrid paraffin oil can be improved by addition of EVA particles. Addition of TiO2 and CuO nanoparticles shows enough improvement in tribological properties of hybrid paraffin oil. Poor oxidative stability of hybrid paraffin oil can be improved by addition of butylated hydroxytoluene (BHT).

Improvement of tribological properties of Al alloy with CNTs and Nb nanopowder for industrial application

Unreinforced Al alloy lacks adequate tribological property required in service. To improve on this property, it must be reinforced with materials having good wear properties. Hence, Al was reinforced with CNTs and Nb and consolidated with spark plasma sintering (SPS). The wear experiment was conducted on a ball-on-disc Tribometer where loads of 10 N, 20 N and 30 N were systematically applied. The coefficients of friction (COF) of the sintered samples were subsequently obtained. The samples were weighed before and after each run to determine their weight losses which were used to compute their wear volumes. The experiment was designed and analyzed with Taguchi and ANOVA. Results showed that Al-8CNTs-8Nb composite had the best wear characteristics. Its COF got improved by 79% which shows that it is suitable for industrial applications.

Mechanical and tribological properties of Al 7075 /SiC/ Graphite hybrid composites processed by powder metallurgy technique

The metal matrix composite strengthened with ceramic material of carbide (SiC) has smart mechanical characteristics. Metal-based composites, however, demand progress in their friction and tribological characteristics. In this work-study an effort is made to design a completely new material through the method of metallurgy by adding graphite, which acts as a solid lubricant. This study explored the effect of graphite on the tribological behaviour of hybrid composite Al 7075/5 wt. % SiC / X wt. % graphite (X=10, 5 and 0). The research confirms the performance of wear properties by incorporating graphite into the composite. The sic-graphite reinforced Al 7075 (aluminium alloy 7075) was studied. Metallurgy route was used to prepare the composites. Microstructures, the mixture of materials, wear and wear resistance properties were analyzed by optical micro cope and scanning electron microscope, XRD, and pin-on-disc apparatus. The freshly developed metal composite has significant improvement in tribological properties with a mixture 5% silicon carbide (SiC) and 5% graphite. The experimental investigations confirm that a sliding distance of one thousand meters and a sliding velocity of 1.5 m / s with an applied load of 5 N leads to minimum wear loss of 0.01062g and coefficient of friction as 0.1278

Investigation of tribological properties and engine performance of polyol ester–based bio-lubricant: Commercial motorbike engine oil blends

This article explores the influence of blending polyol ester–based bio-lubricant with commercial lubricant on engine performance. Polyol esters trimethylolpropane ester and pentaerythritol ester were prepared from Calophyllum inophyllum seeds. Extreme care was taken to minimize deterioration of physicochemical properties when blending bio-lubricant with commercial oil. Blending of bio-lubricant with commercial oil was carried out in 10%, 15%, 20% and 25% volume. The test oils were first investigated for wear and friction properties on a four-ball wear tester. Optimum blending ratio was calculated from results of tribological properties, and the blend with optimum blend ratio was investigated for engine performance. The engine performance of the optimum blends was evaluated by conducting a 60-h endurance test on a motorbike. Significant improvement in tribological properties was observed up to a blending percentage of 15% when blending pentaerythritol ester with commercial oil. In the case of trimethylolpropane ester–based bio-lubricant, 10% blending with commercial oil gave optimum performance. The novel evaluation of engine performance of commercial oil and blends has shown a reduction in the wear of engine components with an encouraging decrease in fuel consumption. Metallographic studies conducted on worn piston rings reveal synergy between additives in the commercial oil and esters in the bio-lubricant in reducing wear and friction, thereby reducing fuel consumption.

Synergistic effect of nano-SiO2 and graphene oxide: hybrid filled thermosetting polyimide nanocomposites with ultralow wear

In this work, nano-SiO2, GO and nano-SiO2/GO hybrid reinforced thermosetting polyimide (TPI) composites are synthesized by in situ polymerization method, respectively, and their mechanical performances are simulated using the finite element software to guide the design and manufacture of these tribological coatings. The tribological results show that the nano-SiO2/GO/TPI hybrid composites demonstrate better wear resistant ability, particularly under high load, than TPI composites that are added anyone of the SiO2 or GO nanoparticles alone, and the lowest wear rate of this hybrid composite 4.25 × 10−8 mm3N−1m−1 is obtained at high load, which is more than 1 order of magnitude lower than pure TPI’s 11.48 × 10−7 mm3N−1m−1. Tribological mechanism analysis shows that the improvement of tribological properties is mainly attributed to the synergistic effect of nano-SiO2 and GO in the tribological process. This hybrid nanocomposites can be promising material used as tribo-material in dry sliding condition under high load, and this study demonstrates a way to design and prepare polymer composite coatings with good tribological properties by considering the synergistic effect of nanosize fillers.

Performance evaluation of hazelnut oil with copper nanoparticles - a new entrant for sustainable lubrication

PurposeThis paper aims to investigate the friction and wear performance of Hazelnut oil with copper (Cu) nano additives.Design/methodology/approachThe experiments were performed on a pin-on-disc tribometer in boundary and mixed lubrication regimes. Copper nanoparticles were added in 0.5 and 1 Wt.% concentrations and corresponding Stribeck curves were generated with a base oil and with oil containing Cu nanoparticles. Surface analysis of aluminium 6061 pins was conducted using an optical microscope, scanning electron microscope and energy dispersive spectroscopy.FindingsThe lubricant with 0.5 Wt.% Cu nanoparticles exhibited better results. An improvement of around 80 per cent in coefficient of friction and around 99 per cent in specific wear rate was observed. The film formation capability of the Cu nanoparticles led to an overall improvement in tribological properties of the base oil.OriginalityExperiments were performed to evaluate the tribological performance of a new lubricant (Hazelnut oil) using Cu nanoparticles. The results obtained herein suggest that Hazelnut oil has a great potential to replace the conventional mineral oils in the field of industrial lubrication.

Improving the Tribological Properties of Polyethylene Products by Modification with Metal Chelate Complexes

The results of studying the improvement of tribological properties of polyethylene products by modification with Nd and Al chelate complexes containing bulky tert-butyl groups in the ligand surrounding are given. The effect of additives on the coefficient of friction and wear of friction parts under static load is studied. The influence of coordination compounds on thermomechanical characteristics of polymers is studied. It is shown the treatment of polyethylene with Nd and Al complexes gives rise to a 1.2- to 1.5-fold decrease in the coefficient of friction and a 1.5- to 2-fold increase in the wear resistance.

Tribological Behavior of Multi-walled Carbon Nanotubes Grafted Carbon Fiber-reinforced Friction Material

Friction characteristics of multi-walled carbon nanotubes grafted carbon fiber-reinforced friction material (MWCRFM), asbestos fiber-reinforced friction material (AFRFM), and oxidized carbon fiber-reinforced friction materials (OCRFM) are investigated in this work using a wear test apparatus. The surface of carbon fiber (CF) is chemically inert and hydrophobic in nature and possesses poor bonding performance with polymer matrix. Hence, in this work, an attempt is made to improve the bonding behavior between CF and remaining ingredients. CF surface is modified by two surface treatment methods. First, oxidation and second grafting multi-walled carbon nanotubes functionalized (MWCNT-F) on CF surface. CF content after surface modification is taken as (5 wt%) and mixed with remaining ingredients of friction material. Composite sheets are prepared by using hand layup method. Three types of friction materials, (MWCRFM), (AFRFM), and (OCRFM) are developed and analyzed for coefficient of friction and wear rate using wear test apparatus. These materials are also characterized for SEM. MWCNTs-F on CF surface is observed. Sample specimens are cut from the composite sheets and the influence of performance properties like speed, load, and time on friction and wear is studied. The back ground for this research work is to identify the best configuration of materials and surface treatment method on CF for the improvement of tribological properties of friction material. The behavior of the samples is also analyzed using regression analysis L9 (3 × 3) experimental design method for three different loads, time periods, and speeds. The results reveal that braking load and time plays an important role to control the friction and wear characteristics of MWCRFM. It was also observed that MWCNT-F grafted on CF possess less wear rate and high coefficient of friction compared to other formulations of materials.

Molecular dynamics simulation of effects of nanoparticles on frictional heating and tribological properties at various temperatures

The temperature of a friction pair exerts considerable influence on the tribological behavior of a system. In two cases, one with and the other without Cu (copper) nanoparticles, the temperature increase in friction pairs caused by frictional heating and its tribological properties at various temperatures are studied by using the molecular dynamics approach. The results show that temperature distribution and surface abrasion are significantly improved by the presence of Cu nanoparticles. This is one of the reasons for the improvements in tribological properties achieved in the presence of nanoparticles. The temperature and range of influence of frictional heating for the model without nanoparticles are significantly increased with the increase in the sliding velocity; however, in the model with nanoparticles, the temperature gradient is confined to the area near the Cu film. With an increase in the temperature of the friction pair, the improvement in anti-wear properties associated with the presence of Cu nanoparticles becomes more significant.

Improvement of Tribological Properties of Steel Camshaft by Plasma Nitriding

Improvement of Tribological Properties of Steel Camshaft by Plasma Nitriding

Research on the Improvement Effect and Mechanism of Micro-Scale Structures Treated by Laser Micro-Engraving on 7075 Al Alloy Tribological Properties.

During various applications in aerospace, ships, autos, and aircraft, 7075 Al alloy will frequently contact other materials, and therefore suffer from slight abrasion. However, the poor tribological properties of 7075 Al alloy greatly affect its performance and life length, leading to limitations in its application. Preparing roughness structures on the surface is regarded as a promising method to improve the properties of materials. However, the tribological properties of 7075 Al alloy cannot be enhanced significantly by roughness structures in complex dynamic changeable environments, owing to the incomplete understanding of the effect of roughness structures. Given the above issues, in this paper, micro-scale structures (linear grooves, gridding grooves, and arc grooves) were designed and prepared on 7075 Al alloy surfaces by a surface treatment (laser micro-engraving), which provides excellent controllability of the morphology and dimensions of as-prepared roughness structures. The tribological properties of the as-prepared surfaces were investigated systemically. The effect of micro-scale structures on the tribological properties was studied. The wear mechanism and tribological properties improvement mechanism of the surfaces were clarified. Furthermore, the effect degree of the enhancement factors of the micro-scale structures on the tribological properties was explored under different conditions. The results indicate that the micro-scale structures play an important role in improving the tribological properties of Al alloy under different sliding speeds. The improvement mechanism can be summarized by four factors. However, the effect degrees of these factors on the tribological properties exhibit considerable differences. This study not only develops specific micro-scale structures that can dramatically improve the tribological properties of 7075 Al alloy under different conditions, but also offers guidance for the construction of appropriate roughness structures that can dramatically improve the tribological properties of Al alloy according to the friction conditions.

THE INFLUENCE OF SILICON-DOPED DIAMOND-LIKE CARBON COATING ON THE WEAR OF IONIC LIQUID LUBRICATED FRICTION PAIRS

This article reports the results of the study of an a-C:H:Si coating doped with silicon and produced by chemical deposition (PACVD). The effect of the coating on the tribological behaviour of IL-lubricated friction pairs was evaluated. The properties of the 100Cr6 steel specimens with and without the coating were compared. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used for imaging the morphology of the coating surfaces and cross-sections and for identifying the elements in the coating composition. The contact angle of the investigated surfaces was measured with an optical tensiometer. Friction tests were performed on a ball-on-disc tribometer under dry friction and when lubricated with trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl) amide ionic liquid. The geometrical structure of the surfaces before and after the tribological tests was measured using an optical profilometer. The ionic liquid used with the silicon-doped diamond-like coating under friction conditions reduced the coefficient of friction and wear. The results obtained from the tests and analysis allow for the conclusion that the use of DLC coatings a-C:H:Si lubricated with trihexyltetradecylphosphonium Bis(trifluoromethylsulfonyl) amide contributes towards the improvement of tribological properties of sliding surfaces under friction.

Solid/liquid lubrication behavior of nickel aluminum-silver alloy under seawater condition

The purpose of this work was to investigate whether a combination of solid lubrication with lubrication by seawater would be a feasible lubrication approach for marine applications such as propulsion system components, pumps, and other machinery. In particular, the friction and wear behavior of a high-strength, intermetallic-based solid-lubricating alloy (Ni3Al-Ag alloy) coupled with Al2O3 ceramic was investigated in simulated seawater. Under seawater conditions, the Ni3Al-Ag alloy exhibited a relatively low friction coefficient of 0.11–0.08 and a wear rate of about 1–2 × 10−7 mm3/Nm. It is proposed that the Ag alleviates plowing and adhesive actions of tribo-pair and retains chemical stability in seawater. Also, the seawater plays lubricating, cooling, and corrosive roles in the friction and wear response of the Ni3Al-Ag alloy. The improvement in tribological properties under seawater conditions is attributed to the synergistic action of solid and liquid lubrication.

Improved tribological property of VN film with the design of pre-oxidized layer

At room temperature, VN films often have a relatively high friction coefficient (COF), which vastly limits their industrial application. In this work, pre-oxidation thermal treatments with different oxygen concentration were applied to improve the room-temperature tribological properties of VN films. The results showed that the V2O5 and VO2 thin pre-oxide layer form under the high and low oxygen concentration, respectively, and after thermal treatment, the tribological properties of VN films are promoted greatly. The VN film with V2O5 thin pre-oxide layer has the lowest COF (~0.23) but the greatest wear rate ((11.41 ± 0.22)× 10–15 m3 N−1 m−1), while the VN film with VO2 thin pre-oxide layer has a relative lower COF (~0.46) as well as wear rate ((2.27 ± 0.14)× 10–15 m3 N−1 m−1) than VN film without a pre-oxide layer. By analysis, the initial existence of V-oxide seems to have a more positive effect than in-situ formation of V-oxide on the improvement of tribological property at room temperature, and the V2O5 plays a decisive role in the decrease of COF, and the VO2 can improve the properties of anti-friction and wear resistance simultaneously. Thus designing a thin pre-oxide layer on the V-based films seems to be a promising method to promote their room-temperature tribological property.