Lubricants definition

Most compounds in which carbon is the key element are classified as organic. Common examples of organic compounds include degreasing solvents, lubricants, and heating and motor fuels. This subsection highlights some of the more common characteristics of organics as they relate to hazards. Various relevant classes of organics are presented in terms of chemical behavior and physical properties. In order to facilitate the discussion to follow, a few basic definitions will be presented first. 

There is a wide range of conversion levels. The term maximum conversion type has no precise definition but is often used to describe a level of conversion, where there is no net fuel oil manufactured. A fuel products refinery with specialities may manufacture lubricating oils, asphalts, greases, solvents, waxes and chemical feed stocks in addition to the primary fuel products. The number and diversity of products will naturally vary from one refinery to another. Refineries produce chemical feed stocks for sale to the chemical affiliates and do not have responsibility for the manufacture of chemical products directly. Both operations may be carried out at the same physical location but the corporate product responsibilities are usually separate. 

Definition of Thin Film Lubrication and Boundary Lubrication... 

The definition of different lubrication regimes is a historic problem [41 ]. In boundary lubrication, molecules will be absorbed on a solid surface of a tribo-pair and form a monomo-lecular absorbed layer as described by Hardy [42] as shown in Fig. 1 (a). If the film thickness of lubricants in the contact region is from a few nanometres to tens of nanometres, different layers will be formed as shown in Fig. 1 (b) proposed by Luo et al. [3,4]. The layer close to the surfaces is the adsorbed film that is a monomolecular layer. The layer in the... 

As described above, the magnitude of Knudsen number, Kn, or inverse Knudsen number, D, is of great significance for gas lubrication. From the definition of Kn in Eq (2), the local Knudsen number depends on the local mean free path of gas molecules,, and the local characteristic length, L, which is usually taken as the local gap width, h, in analysis of gas lubrication problems. From basic kinetic theory we know that the mean free path represents the average travel distance of a particle between two successive collisions, and if the gas is assumed to be consisted of hard sphere particles, the mean free path can be expressed as... 

The agents in this class are bicyclophosphates and bicyclothiophosphates. This class of agents is not specifically listed in the Chemical Weapons Convention nor is it covered by the language of the general definitions in the Schedules. Some of these chemicals have been used as fire retardants, oil lubricants, and for medicinal research. They also occur as breakdown products in some synthetic turbine engine lubricants and some rigid polyurethane foams. 

Tests showed that liquid lubricants do not even provide adequate lubrication in the lower Vacuums of space simulators. Solid lubricants, such as molybdenum disulfide, tungsten disulfide. and the soft metals have given better results. However, the known data about space lubricants are results of simulator measurements made in the pressure range of 10 s to 1C6 torr which does not simulate real space conditions, and therefore, these available data cannot be considered completely valid. It can be expected that definite data on lubricant performance in a vacuum will be obtained by conducting tests in a simulator that reaches the low 10"10 torr range. At this press level, the monolayer formation time is increased to at least several hours which will result in a sufficient time span for observing the metal... 

There is an international standard, ISO 46641 which is written as a guide to dynamic testing and which can be referred to for definitions of terms used and also includes classifications of test machines, preferred conditions, recommended test piece shapes and a bibliography. The British standard is identical (BS ISO 4664). ASTM has taken the same approach but the equivalent2 is more like a small text book and includes some rather unnecessary definitions (e.g. lubricated and relative). Whilst it is some ways a valuable reference, in other respects it is over the top for many peoples testing needs. 

A coarse grayish-green talc rock has been called soapstone or steatite and was formerly much used for stoves, sinks, electrical switchboards, etc, Talc finds use as a cosmetic, for lubricants and as a filler in paper manufacturing. Most tailor s chalk consists of talc. The origin of the word talc is not definitely known. 

Precipitation number the number of milliliters of precipitate formed when 10 ml of lubricating oil is mixed with 90 ml of petroleum naphtha of a definite quality and centrifuged under definitely prescribed conditions. 

The kinetics and thermodynamics of the solubilization and localization of guest molecules into reverse micelles in lubricants are little known. Questions such as What are the driving forces responsible for the uptake of molecules into reverse micelles What are the kinetic steps in solubilization Where is the location of the guest molecules in a water pool or interface - all still await a definitive answer (Luisi et al., 1988 Pawlak, 2001 Willermet, 1998). 

Rowe, G.W., Friction, Wear and Lubrication Terms and Definitions, Organization for Economic Cooperation and Development, International Research Group on Wear and Engineering Materials, Paris, 1969. 

Diesters prepared from specific monohydric alcohols can be formulated into low viscosity partial synthetic automotive crankcase lubricants. These diester basestocks exhibit definite advantages over petroleum basestocks of similar and sometimes higher viscosities. These advantages are ... 

Thus each solid face makes a definite quantitative contribution to the friction, irrespective of what the other solid face may be, or what lubricant is present. At one time Hardy attempted to explain this on the theory that the influence of the attraction of the solid face extended for long distances, but more recent analysis of the occurrences during sliding indicates that the process is very complex, and that the coefficient of friction is not, as a rule, a quantity capable of simple interpretation in terms of the properties of continuous surface films, and of the underlying solid. 

Wettability of a solid surface definition and assessment The concept of wettability of a solid by a liquid is directly related to the wetting processes. This concept is specially useful in the fields of detergency, lubrication or enhanced oil recovery. In the context of the oil industry, proposals were made by Briant and Cuiec (1972) for the experimental assessment of wettability, which was defined in terms of the thermodynamic affinity of a solid surface for a liquid. 

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