Comparative Study Of Tribological Behavior Research Articles

Toward ultralow friction and wear of ultrananocrystalline diamond film by formation of graphene nanosheets with a Cu catalyst

The present work has realized ultralow friction and wear of ultrananocrystalline diamond (UNCD) film through in-situ formation of graphene nanosheets by introducing Cu catalyst. UNCD film was first coated with a Cu layer by magnetron sputtering method and then annealed with the protection of Ar. After that, some thin and wrinkled graphene-like nanosheets were in-suit formed in UNCD film, which avoided the contamination of graphene during transfer process and enabled better adhesion between graphene and UNCD film. A comparative study of tribological behavior of UNCD, Cu/UNCD and annealed Cu/UNCD films were performed against Si3N4 ball on a ball-on-disk tribometer. The results showed that graphene nanosheets over UNCD film enhanced its tribological performance evidently. The annealed Cu/UNCD film exhibited ultralow friction coefficient of 0.025 and a kind of zero wear as the wear track is higher than the film surface. The findings in this study present a novel and effective method to enhance the lubricity of any engineering UNCD film.

Comparative Study of Tribological Behavior of TiN Hard Coatings Deposited by Various PVD Deposition Techniques

In this paper, we present a comparative study of tribological properties of TiN coatings deposited by low-voltage electron beam evaporation, magnetron sputtering and cathodic arc deposition. The correlation of tribological behavior of these coatings with their intrinsic properties and friction condition was studied. The influence of surface topography and the surrounding atmosphere was analyzed in more detail. We limited ourselves to the investigation of tribological processes that take place in the initial phase of the sliding test (the first 1000 cycles). A significant difference in the initial phase of the sliding test of three types of TiN coatings was observed. We found that nodular defects on the coating surface have an important role in this stage of the sliding test. The tribological response of TiN coatings, prepared by cathodic arc deposition, is also affected by the metal droplets on the coating surface, as well as those incorporated in the coating itself. Namely, the soft metal droplets increase the adhesion component of friction. The wear rates increased with the surface roughness of TiN coatings, the most for coatings prepared by cathodic arc deposition. The influences of post-polishing of the coating and the surrounding atmosphere were also investigated. The sliding tests on different types of TiN coatings were conducted in ambient air, oxygen and nitrogen. While oxygen promotes tribo-chemical reactions at the contact surface of the coating, nitrogen suppresses them. We found that the wear rate measured in ambient air, compared with that in an oxygen atmosphere, was lower. The difference is probably due to the influence of humidity in the ambient air. On the other hand, wear rates measured in a nitrogen atmosphere were much lower in comparison with those measured in an oxygen or ambient air atmosphere.

A Comparative Study of Tribological Behavior of Moglice and Dk-6(Pt) Composites

A Comparative Study of Tribological Behavior of Moglice and Dk-6(Pt) Composites

Nickel-catalyzed direct growth of graphene on bearing steel (GCr15) by thermal chemical vapor deposition and its tribological behavior

The present work investigates the friction and wear behavior of graphene synthesized on bearing steel. To avoid the deterioration in the quality of graphene during transfer and to avail the advantage of better adhesion between graphene and substrate, the graphene films were grown directly by thermal chemical vapor deposition on GCr15 bearing steel catalyzed with a layer of electroplated nickel. A gaseous mixture of H2 and acetylene (C2H2) was used to synthesize the graphene films. The effect of growth temperature, reaction time and flow rate on the formation of graphene films was investigated by Raman spectroscopy and scanning electron microscopy. The results indicated that few to multilayer graphene can be grown across the surface of Ni/steel. It was concluded that the graphene quality could be enhanced by optimizing the growth temperature, acetylene flow rate and time. Further, comparative study of tribological behavior of steel, Ni/steel, and G/Ni/steel was performed against steel ball for shorter as well as longer duration and it was concluded that graphene films over nickel catalyzed steel can enhance the tribological performance effectively. Graphene films can reduce the friction coefficient to 0.15 with 2–3 order reduction in wear.

Comparative study of tribological behavior of MWCNTs filled HFRP and unfilled HFRP composites under different sliding parameters and different sliding environment

Industrial application of Hybrid Fiber Reinforced Polymer Composites (HFRP) is increasing day by day. HFRP composites have many advantages such as lightweight, high specific strength etc. which make HFRP composites a suitable material in aerospace industry. This paper compares the tribological properties of HFRP composites and HFRP composites doped with multi-walled carbon nanotubes (MWCNTs) fabricated by vacuum bagging process under different loads and different environments. The experiment was performed on a pin on disc type tribometer with HFRP samples and steel disc of hardness 60 HRC acting as a counter surface. Experimental results depict that addition of MWCNTs improves tribological behavior of the composite. In addition to that morphology of specimens was examined by optical microscope.

Comparative Study of Tribological Behavior of Electroless Ni–B, Ni–B–Mo, and Ni–B–W Coatings at Room and High Temperatures

Ni–B alloys deposited by the electroless method are considered to be hard variants of the electroless nickel family. Inclusion of Mo or W to form ternary alloys improves the thermal stability of electroless nickel coatings. Therefore, in the present work, Ni–B, Ni–B–Mo, and Ni–B–W coatings are deposited; and their tribological behavior at room and high temperatures are investigated. Electroless Ni–B, Ni–B–Mo, and Ni–B–W coatings are deposited on AISI 1040 steel substrates. The coatings are heat treated to improve their mechanical properties and crystallinity. Tribological behavior of the coatings is determined on a pin-on-disc type tribological test setup using various applied normal loads (10–50 N) and sliding speeds (0.25–0.42 m/s) to measure wear and coefficient of friction at different operating temperatures (25 °C–500 °C). Ni–B–W coatings are observed to have higher wear resistance than Ni–B or Ni–B–Mo coatings throughout the temperature range considered. Although for coefficient of friction, no such trend is observed. The worn surface of the coatings at 500 °C is characterized by lubricious oxide glazes, which lead to enhanced tribological behavior compared with that at 100 °C. A study of the coating characteristics such as composition, phase transformations, surface morphology, and microhardness is also carried out prior to tribological tests.

Comparative study of tribological behavior of thin coatings based on metal oxides at various scale levels

Results of tribotests of thin coatings based on multicomponent oxides are presented. Tests have been conducted using two instruments, i.e., a NanoScan-3D scanning nanohardness tester and a UMT-2 tribometer. A comparative analysis of the results of the tribotests has been carried out. The causes of the spalling of the coatings have been studied theoretically and experimentally.

Comparative Study of Tribological Properties of Ni-P Coatings under Dry and Lubricated Conditions

This paper presents a comparative study of tribological behavior of electroless Ni-P coating under dry and lubricated condition based on Taguchi analysis. Mild steel specimens are used as the substrate material for the deposition of Ni-P coating. Based on L27 orthogonal array of Taguchi analysis, the friction and wear tests are conducted on a plate-on-roller type multi-tribotester. Three process parameters viz. normal load, sliding speed and duration of sliding are considered. It is seen that the normal load is the most significant factor followed by sliding speed and sliding time at 99% confidence level in case of friction coefficient. However, for wear normal load and sliding time are significant parameters at same confidence level. Confirmation tests are carried out to validate the analysis. Finally, the surface morphology, composition and compound analysis of the coatings are done by means of scanning electron microscope, energy dispersed x-ray micro-analyzer and x-ray diffraction analyzer respectively.

Exploring tribological behaviour of diamond film by hot-filament chemical vapour deposition on tungsten carbide for lunar exploration

To explore the future application of diamond films coated by hot-filament chemical vapour deposition on tungsten carbide for lunar exploration, a comparative study of tribological behaviour of the film sliding in air and in vacuum under four different temperatures was conducted. Results showed that the coefficient of friction (COF) in air basically decreased with elevated temperature and, in vacuum, increased initially followed by a decrease with elevated temperature. The diamond film surface in air was observed to be smooth at 50 °C and to form a passivation layer that reduces friction at 250 °C. Its counterpart in vacuum was observed: (i) to adhere with debris at 50 °C, (ii) to form a transfer layer by the agglomerated debris at 250 °C, which reduced the friction and increased the level of agglomeration with the elevated temperature, (iii) to crack at 450 °C which subsequently increased the sliding friction. Surface graphitization of diamond was favourable in reducing the COF and detected for the sliding both in air and vacuum when the temperature was approaching 650 °C.

A comparative study of tribological behaviour of dental composites and tooth enamel: An energy approach

In this article, an energy approach based on the correlation between dissipated friction energy and wear volume was used to compare wear resistances of human tooth enamel and four composite dental materials: Arkon, Ecusit, Ful-Fil, and Filtek. The results of the study showed that the wear resistance of enamel is approximately one order or more higher than the one obtained for the dental materials. The effectiveness of the approach used has also been shown. Scanning electron microscopy (SEM) examinations and chemical analysis surfaces subjected to tribological experiments made it possible to uncover substantial differences in the wear mechanisms occurring on enamel and the dental material surfaces. The wear mechanism of the dental materials used in the study is characterized mainly by chemical changes, while enamel is mainly subjected to physical transformations.

A new tribometer for friction and wear studies of dental materials and hard tooth tissues

This paper presents a new tribometer developed for a study of the tribological behaviours of dental materials and hard tooth tissues. The device simulates oral kinematic conditions and the loading produced during masticatory process. The tribometer is similar to the existing devices regarding the kinematic features, i.e. it produces an adjustable oscillating movement. However, the device machine is equipped with a unique pneumatic system of loading controlled via computer by special software called TOOTHY. The programmable system allows easy adjusting of the loading parameters such as the magnitude of normal force and its amplitude or pattern of cyclic loading. In this way different combinations of loads can be applied thus making the investigation of different wear situations possible. The device has two full bridge strain gauges for the measurement of loading and friction forces, by which the coefficient of friction is determined. The use of the tribometer is illustrated by a comparative study of tribological behaviour of human enamel subjected to two- and three-body friction, and to two different loading patterns as well. The obtained results are discussed.

A comparative study of tribological behavior of microarc oxidation and hard-anodized coatings

Microarc oxidation (MAO), a novel coating technique capable of depositing dense, hard ceramic composite coatings on aluminium and its alloys, has the potential to replace conventional hazardous anodizing techniques. However, the emergence of such a scenario depends strongly on the properties and performance of MAO coatings in comparison to hard-anodized coatings. In order to facilitate such a comparative investigation, a 6061 T6 aluminium alloy was employed as the substrate and the coatings were deposited through microarc oxidation (MAO) and hard anodizing techniques. The tribological performance of the coatings was evaluated using dry-sand abrasive wheel tests at different normal loads and solid-particle erosion wear tests at different particle velocities and impact angles by employing silica as erodent. The hard-anodized coatings reduced the abrasive wear rate of 6061 Al alloy by a factor of 2, while the MAO coatings reduced the wear rate by a factor of 12–30. Under erosion conditions, the overall wear rate of MAO coatings is identical to that of bare alloy, whereas the hard-anodized coatings exhibit 10 times higher erosion rate.

A Comparative Study of Tribological Behavior of Plasma and D-Gun Sprayed Coatings under Different Wear Modes

In recent years, thermal sprayed protective coatings have gained widespread acceptance for a variety of industrial applications. A vast majority of these applications involve the use of thermal sprayed coatings to combat wear. While plasma spraying is the most versatile variant of all the thermal spray processes, the detonation gun (D-gun) coatings have been a novelty until recently because of their proprietary nature. The present study is aimed at comparing the tribological behavior of coatings deposited using the two above techniques by focusing on some popular coating materials that are widely adopted for wear resistant applications, namely, WC-12% Co, A12O3, and Cr3C2-MCr. To enable a comprehensive comparison of the above indicated thermal spray techniques as well as coating materials, the deposited coatings were extensively characterized employing microstructural evaluation, microhardness measurements, and XRD analysis for phase constitution. The behavior of these coatings under different wear modes was also evaluated by determining their tribological performance when subjected to solid particle erosion tests, rubber wheel sand abrasion tests, and pin-on-disk sliding wear tests. The results from the above tests are discussed here. It is evident that the D-gun sprayed coatings consistently exhibit denser microstructures and higher hardness values than their plasma sprayed counterparts. The D-gun coatings are also found to unfailingly exhibit superior tribological performance superior to the corresponding plasma sprayed coatings in all wear tests. Among all the coating materials studied, D-gun sprayed WC-12%Co, in general, yields the best performance under different modes of wear, whereas plasma sprayed Al2O3 shows least wear resistance to every wear mode.