Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
The fatigue and wear characteristics of AISI VIM-VAR M50 steel were evaluated using three fully formulated synthetic ester-based lubricants. Tests were conducted using a rolling contact fatigue test rig of the ball-on-rod type at a cyclic maximum hertzian stress level of 4.83 GPa (700 klbf in −2 ) and temperatures of 23°C (74°F) and 177°C (350°F). The lubricants evaluated included three polyol...
The tribological properties of P-containing antiwear (AW) and extreme pressure (EP) additives in the sliding of steel against aluminum alloy were investigated by Optimol SRV tester. It was found that phosphates reduces the friction coefficient of base stock. However, all P-containing AW and EP additives produce larger wear volume than base stock. The relationship between tribological properties of...
Experiments are described in which a hard half-wedge, representing a scaled up model asperity, was indented into the horizontal surface of a relatively soft specimen with the specimen then moved in a direction parallel to its surface and normal to the wedge edge. Forces measured at the wedge-specimen interface are used to investigate the state of lubrication at the interface at all stages of the experiment,...
The tribological properties of diol compounds in the sliding of steel against aluminum alloy were investigated using an oscillating friction and wear apparatus with the ball-on-block geometry. It was found that molecular structure of diols is important, e.g. 1,3-butanediol is most effective in reducing the friction and wear as compared with 2,3- or 1,4-substituted compounds. The relationship between...
The friction coefficients for copper pairs lubricated with fatty acids and fluorinated fatty acids have been measured over a wide range of sliding speeds and temperatures. Sliding speeds in the range 10 -7 -10 -2 ms -1 and temperatures in the range 4.2-300 K were used. The friction coefficients near 300 K are generally low and increase with sliding speed, while...
The mechanisms of boundary lubrication were investigated by comparing the capability of selected oil blends to protect 52100 steel, silicon nitride, and partially stabilized zirconia from wear. A four-ball wear tester was used and the test parameters were varied to find the optimum conditions for each material/lubricant combination. Additives were considered effective when both the wear rate in the...
The fatigue and wear characteristics of AISI VIM-VAR M50 steel were evaluated using two high-temperature synthetic turbine engine lubricants. Rolling contact fatigue (RCF) tests were conducted on a ball-on-rod type rig at a cyclic Hertzian contact stress of 4.8 GPa (700 ksi) and temperatures of 177°C (350°F) and 274°C (525°F). The two lubricants tested included a five-ring polyphenylether (MIL-L-87100,...
The film-forming properties of lubricant base fluid mixtures in elastohydrodynamic contacts have been studied using ultrathin film interferometry. It has been shown that in binary mixtures where one of the components is more polar than the other, the EHD film thickness formed in the very thin film (< 10 nm region) is controlled by the viscosity of the polar component rather than the viscosity of...
Wear tests were performed in five oil formulations using AISI-52100 balls softened down to 35 Rc. Two configurations were used: four tempered balls, and three tempered balls with a hard spindle ball. The antiwear additives gave low wear constants at all hardnesses except for the softer balls in the four-tempered-balls configuration. Indeed, in many instances moderate softening of the steel actually...
A large class of tribological contacts involve two components, each carrying finite roughness, sliding over one another for many repeated cycles of operation. Although the initial contact may be plastic the steady state situation is one of elastic stress fields in each consistent with the presence of a low shear strength boundary film on one or both of the surfaces. In order to relate the overall...
In this paper we describe our investigation of tribochemical reactions of dibenzyl and diphenyl disulphides in boundary lubrication. We used four-ball wear testing and quantitative analysis of thio byproducts in our studies. We determined the contents of disulphides, thiols, monosulphides, sulphurised hydrocarbons, elemental sulphur, a few phenyl ring thioethers in oil solution and iron sulphide on...
While investigating the problems of high temperature lubrication of adiabatic diesel engines, it was discovered that boundary lubricant films could be transformed into reacted films in an extremely short period under certain reaction kinetics after the oil films had lost their lubrication efficacy. The reacted films consisted of in situ formed graphite and MoS 2 . A performance index R is...
There is a need to better understand the behavior of perfluoropolyalkylether (PFPAE) fluids under boundary lubrication so that their interaction with metal surfaces may be modified by additives or by other means. In this study, the effects of temperature, substrate steel type, an antiwear additive, and atmospheric humidity on the protective surface film formation in a linear PFPAE fluid were studied...
The wear of ultra-high molecular weight polyethylene (UHMWPE) bearing surfaces in prosthetic joints is a significant clinical problem. Wear studies on prosthetic joints are therefore necessary in the improvement of their long-term performance. However, there is no practical and reliable lubricant available for the wear tests. The present study was the beginning of the development of artificial joint...
Impressive strides have recently been made in the field of tribology through molecular dynamics (MD) simulations. A convergence of MD and experiment has led to optimism in scientific circles that the mechanisms of friction and boundary lubrication, studied for centuries, can soon be understood and predicted by first principles. However, from the engineering point of view, practical predictive ability...
The tribological properties of Cl-containing antiwear (AW) and extreme pressure (EP) additives in the sliding of steel against aluminum alloy were investigated by an Optimol SRV tester. It was found that Cl-containing additives were effective at reducing the wear of aluminum. The acting mechanism of Cl-containing additives in the lubricated aluminum-on-steel system was proposed.
Wear of steel (AISI M-50 and AISI 52100) bearing balls in lubricated rolling contact with ground and ground-and-lapped silicon nitride rods was studied using a ball-on-rod rolling-contact-fatigue (RCF) tester. The steel balls suffered significant wear in rolling contact with the as-ground (R a = 0.18 μm) silicon nitride rods. The wear volume loss was approximately linear with the rolling distance...
For the combinations of an Si 3 N 4 pin and five kinds of ceramic disk (SiC, Si 3 N 4 , Al 2 O 3 , ZrO 2 , TiC), a friction and wear test was carried out in ethanol and in ethanol containing iron particles (1 wt.%, average diameter d = 200 nm, d = 12 μm under cohered condition) under a load in the range 5.88-11.50 N, at a sliding velocity of...
As a part of ongoing research intended to produce a reliable artificial joint fluid for wear tests of prosthetic joint materials, the lubricating properties of soybean lecithin and soy protein were studied. For comparison, wear tests were done with bovine serum, and with joint fluid aspirated from a prosthetic hip joint at revision operation. The tests were done with ultrahigh molecular weight polyethylene...
Influence of boundary layers on wear transition from mild to severe conditions in sliding lubricated contacts is experimentally studied. A servohydraulic controlled ball-on-disc tribometer is used. During running, additives in lubricants form boundary layers, which influence the lubrication positively in mixed and boundary lubricated contacts. However, it is not clear if and to what extent boundary...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.