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Earlier studies on the use of the concept of tribopolymerization as an anti-wear mechanism for ceramics involved liquid carriers such as pure hydrocarbons (e.g. hexadecane) and mineral oils at temperatures ranging from ambient to 150 o C. Recent studies have been carried out to determine the effects of potential tribopolymer-forming compounds on ceramic wear in the vapor phase using an inert...
In the present paper, the tribological behaviors of gadolinium dialkyldithiophosphate (GdDDP) were evaluated on friction testers. Thereafter, the tribochemistry of GdDDP were investigated through scanning electron microscopy (SEM), Anger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The results indicated that GdDDP possesses very good antiwear and friction-reducting capacities;...
An apparatus has been constructed to characterize the chemical intermediates and products of tribochemical reactions in situ by means of internal reflection spectroscopy. Diamond-like carbon (DLC) films were deposited by plasma chemical vapor deposition on rubbing substrates and on a germanium internal reflectance element. Spectra were taken in situ while rubbing the surfaces together under moderate...
Si 3 N 4 -based ceramics have been used for machining cast iron at very high speeds. However, they have been found to be unsuitable for machining steel because of the severe wear of the ceramic cutting tools, which is thought to be mainly caused by the chemical dissolution of the ceramic in the chip at the high temperatures reached at the cutting edge. In this paper, a simulation test...
Reciprocating tests were carried out on a number of different ceramics at a range of temperatures up to 1450°C in a high precision test system. The friction that was generated, and the damage to surfaces, were investigated. The aim of the experiments was to investigate the tribology of high-temperature ceramic contacts, and to provide data for high-temperature engineering applications of ceramics...
Friction and wear tests of pure polymers, polytetrafluoroethylene (PTFE), nylon 6, and polymethyl methacrylate (PMMA), vs. stainless steel were carried out on an MM200 tester. The XPS spectra and the atomic relative concentrations of elements on friction surfaces of stainless steel were analysed. The ESR spectra of radicals in polymer wear debris were determined. The results indicate that complex...
The tribological properties of the borate modified by N-containing compound were investigated with a four-ball tester. The boundary film on the rubbed surface were analyzed using a small area X-ray photoelectron spectrometer (XPS), the depth profiling XPS and the Auger electron spectroscopy (AES). Results of the tribological properties indicated that the borate modified by N-containing compound possesses...
The microstructure of wear debris originating in sliding tests from pure metals which form stable metal oxides with the rutile structure (like: manganese, tin and titanium) has been investigated by analytical TEM. The influence of the oxidation reaction on the formation of either amorphous or nanocrystalline debris was studied. Data on wear debris generated on manganese and tin are presented and compared...
The present paper deals with the fundamental understanding on the tribochemical mechanism of tungsten carbide (WC) coating and titanium alloy tribo-couples system. The tribological experiments were performed with a Timken-type tester. Water containing water-soluble additives was employed as the lubricating media. The rubbed surfaces of the carbide coating were characterized with scanning electric...
The Langmuir-Blodgett (LB) films of fatty acids including stearic acid (SA), arachidic acid (AA) and behenic acid (BA) and that of MoS 2 nanoparticles modified with dialkyldithiophosphate were prepared on a glass substrate. The tribological properties of the LB films were systematically investigated, and the structural changes of the LB films during friction process were analyzed with Fourier...
The role of transfer phenomena in the mechanisms of friction reduction by organic molybdenum compounds is studied with the aid of ultrahigh vacuum (UHV) analytical tribometry. Additives used are zinc dithiophosphate (Zndtp), molybdenum dithiophosphate (Modtp), molybdenum dithiocarbamate (Modtc) and Modtc/Zndtp combinations. Experiments involve UHV friction tests on tribofilms formed previously and...
Friction and wear tests of various polymers/stainless steel, PTFE/various metals and JS material (a multilayer composite)/stainless steel were carried out. The XPS spectra and atomic relative concentrations of elements on mating surfaces, the EPM spectra of element line distributions on frictional surfaces and the ESR spectra of radicals in polymer wear debris were determined. The test results indicated...
Formation of tribochemical layers and microstructural surface alterations during mild reciprocating sliding wear of AISI 52100 steel were studied under boundary lubricated conditions using a non-additive hydrocarbon lubricant. At the onset of relative motion no friction-induced chemical processes could be detected due to the protecting natural oxide film on the contacting steel surfaces. After a few...
Different and sometimes contradictory assessments of the importance of thermal and mechanical effects on tribochemical reactions in fretting have been reported in the literature. In our study of fretting wear between steel and silicon nitride ceramics, tribochemical reactions were determined to play the critical role under both non-lubricated and oil-lubricated conditions. Various possible effects...
The purpose of this paper is to present experimental research work seeking a better understanding of triboemission and its role in tribochemistry. A new instrument is described for measuring the intensity and retarded-energy spectra of electrons and ions triboemitted from various sliding contacts. This instrument was designed to accommodate a variety of contact geometries and it features a wide range...
In many fretting investigations, tribochemical reactions have been reported to critically determine the wear and friction behavior, however, different and contradictory assessments of the importance of mechanical and thermal effects on these reactions have been suggested. Since fretting is characterized by relatively slow sliding speeds, high temperatures are not generated over the entire nominal...
This paper reports the results of constant speed drag tests on disks with four different lubricants using an ultra-high vacuum (UHV) tribochamber equipped with a mass spectrometer (MS). An optical surface analyzer (OSA) is also used to observe lubricant migration. Based on the analysis of the experimental results, we propose that, in the case of diamond-like carbon (DLC)-coated sliders, the durability...
Tribochemistry-including chemical reactions at sliding surfaces in contact-is an important factor in boundary lubrication and the formation of protective films. It is a complex subject quite different from conventional glassware studies and may involve effects of high temperatures produced by friction, the emission of charged particles and high pressure.In previous theoretical studies based on a general...
The influence of tribological conditions on the surface reactions occurring between zinc dialkyldithiophosphate (ZnDTP) and steel surfaces has been studied by means of a combination of X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), in situ attenuated total reflection (ATR) infrared spectroscopy, and high-throughput combinatorial approaches. Purely...
Ball-on-plate sliding friction experiments were designed and performed to show the possibility of local friction control by electrochemical methods. By partitioning a metal plate into charged and uncharged zones, the friction coefficient in these zones can be differential when an external voltage is applied during rubbing. It is also possible to achieve differential friction at different locations...
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