Добірка наукової літератури з теми "Raman Tribometer"

The focus is on the oxidation resistance and tribological performance of ta-C and Al2O3/ta-C coatings. The wear tests were carried out on the ball on disc tribometer at room (25 °C) and high (400, 450 and 500 °C) temperatures in ambient air with Si3N4 balls as counterbodies. Scanning electron microscopy and Raman spectroscopy were used to analyze the surface morphology and chemical bonding, respectively. The Al2O3/ta-C coating exhibited better oxidation resistance and tribological performance at elevated temperatures than the ta-C coating. The Raman analysis revealed that a thin alumina layer suppresses structural changes in the ta-C coating at elevated temperatures, thus preserving the sp3 content.

Laboratory scale studies of tribological properties of nitride coatings are useful in predicting their protective wear behavior in cutting tools for industrial scale applications. Main aim of this research is to determinate optical and tribo-mechanical properties in multilayer coatings of metal-ceramic assigned as coatings A and B. These coatings were deposited by DC magnetron sputtering on carbon steel AISI 1060 using buffer adhesion layers of W, Ti/W/WN and TiN/TiN respectively. For to determinate molecules interactions of materials were analysed by means of Raman and FTR spectroscopies. The nanohardness, tribological and adhesion behaviour were studied by nanoindentation, pin on disk and a tribometer. The hardness and behaviour tribological, were obtained by Nano-indentation, pin on disk, and scratch test using a tribometer. FTIR and Raman analysis shown the formation of Ti metallic ion and WO3 mainly in both coatings. The hardness of coatings shown a slight improvement compared with the substrate. However, for industrial application this property should be increase. The behaviour of COF does not presented improvement. The mass loss and wear rate were high significantly due to the formation of cracks on surface coatings. Scratch analysis, it found three wear mechanics determined by the presence of irregular borders with sharp shadow, semicircle detachment in coatings and coatings detachment in the central track as the load increased.

Polyoxymethylene copolymer (POM-C) is the most prominent engineering thermoplastic consisting of repeating carbon-oxygen bonds in the form of oxymethylene groups (OCH2). It is widely used to make small gear wheels, ball bearings, precision parts, automotive and consumer electronics. In this study, the POM-C round blocks were irradiated with 165 KeV electron beam energy in five doses (100, 200, 300, 500 and 700 kGy) in vacuum condition at room temperature. The wear rate, surface hardness and morphological properties of electron beam dose irradiated POM-C blocks surfaces have been analyzed using pin on disk tribometer, optical microscopy, nano-indenter, Raman spectroscopy, 3D nano surface profiler and scanning electron microscopy (SEM). The electron beam irradiation transferred the wear phenomena of unirradiated POM-C sample from the abrasive wear (plough and cracks), adhesive wear (grooving/striation, micropitting) and scraping to mild scraping and striation for the 100 kGy dose irradiated POM-C sample due to cross-linking (macroscopic networks), chemical free radicals formations and partial physical modification (smoothness), which can be concluded from tribometer, optical microscopic, SEM and Raman spectroscopic observations. It also reduced the surface wear rate and average surface roughness with increasing microsurface hardness at threshold value of cross-linking among all unirradiated and others doses irradiated POM-C blocks. The level of tribological (wear and morphology) attribute improvement relies on the electron beam irradiation condition (energy and dose rate) depending on chemical and physical factors of polymeric materials.

Microcrystalline diamond (MCD), nanocrystalline diamond (NCD) and microcrystalline and nanocrystalline composite diamond (MNCD) films are all deposited on flat square shaped WC-6%Co substrates by using bias-enhanced hot filament chemical vapor deposition (HFCVD) apparatus. The diamond films are characterized with scanning electron microscope (SEM) and Raman spectrum. Typical diamond film features are exhibited in the observation of SEM and the analysis results of Raman spectrum. The tribological properties of diamond films against zirconia ceramic are conducted on a ball-on-plate type rotating reciprocating tribometer in ambient air. The average friction coefficients of MCD, NCD and MNCD film in stable period are 0.205, 0.181 and 0.138 respectively. The images of surface topography based on white-light interferometer suggest a very low wear rate of CVD diamond film.

In this work, the metal phase MoS2 was prepared by a simple one-step hydrothermal method, and it was systematically studied by XRD, Raman, SEM, TEM, and other characterization methods. In addition, the tribological behavior of M-MoS2 in water-based drilling fluids has been extensively studied with a ball-disk tribometer. In addition, the influence of applied load and speed on friction performance is also studied. The experimental results show that the introduction of M-MoS2 significantly reduces the friction and wear of the material. Among them, M-MoS2-5-water-based drilling fluid has the lowest friction coefficient (~0.11).

Graphite-containing plasma electrolytic oxidation (PEO) composite coatings were prepared on Al alloy using periodically constant voltage, with addition of graphite in silicate electrolyte. The surface and cross-sectional morphologies of the coatings were examined using scanning electron microscope (SEM), the composition of the coatings was investigated by X-ray diffraction (XRD) and Raman spectra, the tribological properties of the coatings were evaluated on a tribometer. The results show that friction-reducing PEO composite coatings on Al alloy can be prepared in graphite-dispersed electrolyte using periodically constant voltage, the yielded coatings exhibit relatively lower and more stable friction coefficient.

This Research aimed to improve the tribological properties of commercially available lubricating oil (5W-40) by incorporating CuO nanoplatelets (NPs) synthesized using a simple and cost-effective sonochemical method. To evaluate the performance of the nanolubricant, a reciprocating tribometer was indigenously designed and developed to measure the coefficient of friction (COF) and wear tracks between two AISI 1045 steel surfaces. The CuO NPs were characterized using XRD to confirm their purity and phase, while SEM and FE-TEM were utilized to study their morphology and composition. Raman spectroscopy was used to reveal three distinct Raman active peaks of CuO at 283, 330, and 616 cm−1. Zeta potential measurements demonstrated good dispersion quality, with a value of 92.0 mV for 0.1% concentration. SEM and FE-TEM analysis of the nanolubricant showed the formation of a tribo-film over the CuO NPs and adding 0.1% CuO NPs reduced COF by 32%. These findings suggest that incorporating synthesized CuO NPs in commercially available lubricating oil can enhance its tribological properties, leading to improved machine efficiency and lifespan, as well as reduced energy demand. Overall, the study demonstrates the potential benefits of using CuO nanoplatelets as an additive in lubricating oil, which could have significant implications for the development of more efficient nanolubricants.

Graphite-like carbon films were deposited on DC53 steel substrate by unbalanced magnetron sputtering. The microstructures of the resultant films were investigated by Raman spectroscopy, scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD), respectively. Ball-on-disc tribometer was employed to analyze the tribological properties of the film. The results show that the films were dominated by sp2 sites. The surfaces are uniform and dense, the sectional morphology of the films present dense columnar crystal. The films have superior tribological properties under different loads, including low friction coefficient (0.18-0.33) and low wear rate (2.53×10-17m3/(Nm)- 8.47×10-17m3/(Nm)).

At present, cost-effective coatings that cause less pollution are in great demand; to decrease frictional losses, carbon-based hybrid composite coatings have been developed using a high-velocity oxy-fuel (HVOF) spray process. The microstructural, tribological, corrosion, and mechanical properties of these coatings have been evaluated using high-resolution X-ray diffraction (HRXRD), field emission scanning electron microscopy-Energy dispersive X-ray Spectroscopy (FESEM-EDS), Raman spectrum, Vickers micro-hardness tester, µ-360 cos(α) residual stress analyser, corrosion tester, and high temperature tribometer. The residual stress, corrosion and tribological behaviour at high temperatures were investigated using a pin-on-disc high-temperature tribometer. The tribological performance was evaluated using a high-temperature tribometer, and the experimental result shows that a coefficient of friction (COF) varies from 0.12 to 0.52, while wear results were in the range of 45 µm to 120 µm, as the test condition of temperature ranging from 50 °C to 350 °C, load from 60 N to 90 N and sliding velocity from 0.1 m/s to 0.4 m/s respectively. The experimental results of corrosion testing show that the mass loss decreases from 0.10 g to 0.04 g, when samples were dipped for 1 h; when the samples were dipped for 8 h, the mass loss of hybrid composite coating varied from 0.12 g to 0.045 g. The tribological test showed a 78.9 % increase in micro-hardness, a 78 % decrease in residual stress, and 60 % and 62.5 % decreases in mass loss due to corrosion at 1 h and 8 h, respectively, a 76.9 % decrease in COF and 62.5 % reduction in the wear at test condition of 350 ºC temperature, a sliding velocity of 0.4 m/s and 90 N load.

This master thesis work is performed at ABB Corporate Research Center inVästerås. The aim of this study is to investigate Ag:graphene composites as slidingelectrical contacts, suitable for use in e.g. tap-changers. Three different graphenematerials, all produced by a low-cost exfoliation process, are evaluated in this study. The results are compred to an ongoing work on Ag:GO (graphene oxide) composites. This material has shown very good tribological properties, however it hasbeen difficult to handle during sintering processing. The goal of this study is to geteven better tribological, electrical and mechanical properties than Ag:GO, and also todevelop a new powder-metallurgical method to produce the Ag:graphene composites.The study also investigates the influence of graphene flake size and concentration aswell as microstructure of the Ag:graphene composites. This report focuses on aninvestigation of the graphene raw material quality from the suppliers, and friction,wear and resistance analysis of the composites. This is done by using Ramanspectroscopy, SEM with EDS, LOM, tribometer tests and resistivity analysis. Raman and SEM analyses show that none of the supplied LEG materials are ofhigh-quality G (single or bilayer), but rather multi-layer graphene or even graphite.Small amounts of graphene added to Ag gave extremly low friction (μ<0.2 vs. pureAg μ~1.3, 5 N load and 5 cm/s speed). The composite manufacturing process hadcritical steps, which have to be optimized, to obtain low values of friction. Severedegassing of the composites was observed for some sampes, but the samples stillmaintained good friction values. SEM and EDS analyses of 2dfab’s wear track show abuild-up thin carbon-containing tribofilm on the Ag surface. Indicating that G ispresent, and works as a lubricant, creating good tribological properties. The resultsfrom this project may for sure be of importance for future ABB products in specificindustrial applications.

In conventional tribological experiments that study friction and wear behavior of materials, the contact interface is hidden by the contacting bodies. The physical or chemical phenomena taking place at the interface must then be examined through intermittent tests. These kinds of postmortem studies have remained speculative and model based. The inadequacy of such analysis has long been recognized. For a fundamental understanding of interfacial phenomena, it is important to study interactions in real-time. The present work attempts to overcome this hidden-interface problem by developing a tribometer using optically transparent surfaces which can carry out real-time tribological experiments under a microscope equipped with a Raman spectrometer. Such a micro-Raman system enables combined optical imaging capability with chemical mapping and is consequently a promising tool for in situ studies in tribology. Chapter 2 describes the development of a novel in situ total internal reflection (TIR) Raman tribometery, a technique based on TIR Raman spectroscopy combined with tribological experiments. The in situ TIR-Raman tribometer test rig is based on a ball-on-flat geometry. The rotating ball is immersed in an oil bath and carries a film of lubricant while rotating as it rubs against a flat (transparent) surface. Raman spectra of the lubricant are recorded from the contact region through the transparent window as a function of load, time, and velocity. A unique advantage of the TIR technique is that the sample can be analyzed from a known depth beneath the interface using evanescent waves. The capabilities of this TIR Raman tribometer have been demonstrated by carrying out experiments with known solid lubricant material molybdenum disulfide (MoS2). MoS2 is known for its solid lubricant properties. Nanoparticles of MoS2 are used as an anti- wear additive in engine oil. The commissioning of the tribometer rig was carried out using MoS2 nanoparticles to lubricate a steel-steel contact. Before carrying out in situ Raman tribometry on MoS2 nanoparticles, a set of characteristic friction and wear data was obtained from MoS2 nanoparticle-lubricated steel- steel contact (chapter 3) and compared with the data obtained from a commercial tribometer. In addition, friction characteristics of dry MoS2 and MoS2- hexadecane lubricated steel-steel contact were studied as a function of temperature. The friction in the dry particle lubrication was found to increase with temperature while the friction in wet condition was found to decrease with increasing temperature. Micro-Raman and FTIR spectroscopy are used to explore the roles of environmental moisture and chemical degradation of oil on the formation of antifriction films on the steel substrate. Ex situ optical and Raman analysis revealed the formation of an anti-friction film on the steel substrate. To understand the underlying mechanism of nanoparticle lubrication, in situ Raman tribometry was performed and results are presented in Chapter 4. By combining in situ optical imaging and Raman spectroscopy, the sliding history in friction-induced material transfer of dry 2H-MoS2 particles in a sheared contact was studied. Video images in contact showed the fragmentation of lubricant particles and build-up of a transfer film. Contact imaging was used to measure the speed of fragmented particles in the contact region. Total internal reflection (TIR) Raman spectroscopy was used to follow the build-up of the MoS2 transfer film. The combination of in situ and ex-situ analysis of the mating bodies was used to understand the mechanism of transfer film formation in the early stages of sliding contact. Application of in situ TIR Raman tribometry for the study of liquid lubricants was demonstrated by using PAO to lubricate SF10 glass – silica contact and results are discussed in Chapter 5. It is well established that under high shear rates, synthetic base oils undergo shear thinning. Earlier studies of shear thinning relied mainly on viscosity measurements from which it is not possible to obtain information on molecular alignments or ordering. In the present study, TIR Raman spectra were used to estimate the thickness of the lubricant film under sliding conditions and polarized Raman data was used to study the alignment of molecules during shear thinning. The experimentally obtained film thickness data was superposed with theoretical calculations and a transition from Newtonian to non-Newtonian behavior was observed at high shear rates. Also, the effect of additive molecules on the shear thinning behavior of poly alpha olefin lubricant was studied. The in situ TIR Raman tribometer is a powerful tool to detect the physiochemical changes lubricants undergo at the hidden interface under sliding conditions. The capability of this technique in enabling tribological processes to be observed dynamically in real time with concomitant chemical changes at the interface has the potential to make it an indispensable tool in fundamental studies of tribological interactions. The application of total internal reflection resulted in significant signal enhancement which makes the technique developed in this study an important addition to the already available ones for future tribological studies. The information and insight generated in a range of tribological phenomena taking place at the hidden interface of contact will be useful in developing new lubricant materials.

The array films of amorphous carbon nanorods were prepared by thermal catalytic pyrolysis of acetylene at 650°C on a porous anodic aluminum oxide (AAO) membrane with Co-Ni catalysts. The morphology and microstructure of the array films were examined by scanning electron microscopy (SEM) and Raman spectroscopy. The friction properties of array films of amorphous carbon nanorods were investigated using a ball-on-disk tribometer and a friction force microscopy (FFM) in ambient air. The friction coefficients of the array films were influenced by the graphitization degree of the amorphous carbon nanorods. The amorphous carbon film with high graphitization degree showed low friction coefficient.

Ultra-thin tetrahedral amorphous carbon (ta-C) films were deposited by the filtered cathodic vacuum arc (FCVA) technique. The thickness, structure, and topography of the films were studied by various analysis methods, such as auger electron spectroscopy (AES) depth profile, high resolution transmission electron microscope (HRTEM), Raman spectroscopy, and atomic force microscopy (AFM). A tribometer was used to investigate the tribological properties of the ta-C films. The results indicate that ta-C film with thickness less than 2 nm can be obtained by the FCVA technique. As the film thickness increases the relative intensity ratio ID/IG decreases, which means that sp3 bond in the films increases. The oxide layer cleaning procedure of silicon substrate before deposition influences the growth mode and surface roughness of the films. The ultra-thin ta-C film has the lowest friction coefficient of 0.19 and excellent anti-wear properties.

Abstract. The paper presents the results of the research on the tribological properties of the DLC coating. The coating was applied using plasma-assisted chemical vapour deposition (PACVD). The obtained coating was determined to be a DLC coating using a Raman spectroscope. Friction tests were performed using a tribometer working in a ball-disc friction configuration at various loads applied. For the tests, a disc with a DLC coating was used as a sample, and a ball made of 100Cr6 steel was used as a counter-sample. The friction tests were carried out in the conditions of technically dry friction. Examination of the coating was done using a scanning microscope. Analysis of the geometric structure of the sample before and after the friction test was performed using a confocal microscope with an interferometric mode. The obtained test results indicated that the properties of DLC coatings are influenced by the deposition process conditions: the argon and methane flow ratio. Whereas the deposition time influences the tribological properties.

Abstract An ultrasonic nanocrystal surface modification (UNSM) technique was applied to the thermally sprayed yttria-stabilized zirconia (YSZ) ceramic thermal barrier coating (TBC) deposited onto a hot tool steel substrate to improve the mechanical and tribological properties. The surface microstructure of the as-sprayed and UNSM-treated coatings was examined using a scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy, while the hardness of the coatings was measured by Vicker`s hardness tester. The friction and wear behavior of the coatings was assessed using a ball-on-disk tribometer against bearing steel (SAE52100) ball at temperatures of 25 °C and 200 °C under dry reciprocating conditions. Results showed that the UNSM-treated coating had smoother surface, lower friction and higher resistance to wear compared to that of the as-sprayed coating. It was found that hybrid use of thermal spray coating (TSC) and UNSM technique is meaningful to bring together synergy effect of two emerging surface technologies.

Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.