In lubricant film

Coppeta et al. [10] made slurry film measurements during using laser-induced fluorescence. By addition of a fluorescent dye to the polishing slurry film thickness was experimentally from the fluorescence intensity of the lubrication film as measured through a transparent substrate. Film thickness measurements were in good agreement with those of Levert et al. [7,8]. This technique can also be used to study slurry transport across the wafer surface, diameter variation in lubrication film thickness, and slurry mixing effects [11]. 

Figure 2-6. Pivoted slider bearing with diagram of pressure profile in lubricant film.

Jabbarzadeh, A., HarroweU, R, and Tanner, R.l. Crystal bridges, tetratic order, and elusive equilibria The role of structure in lubrication films. 2007. 7. Phys. Chem. Sill 11354. 

More recently in 1933 A. Kingsbury [9] published a paper entitled "Heat effects in lubricating films" which was both theoretical and experimental. 

KINGSBURY, A. "Heat effects in lubrication films". Mechanical Engineering, n 55, 1933, 685-688. 

HAGG, A.C. "Heat effects in lubricating films", Journal of applied mechanics, n 11, 1999, 72-76. 

PAN, C. H. T., "Calculation of Pressure, Shear, and Flow in Lubricating Films for High Speed Bearings", Trans. ASME, Journal of Lubrication Technology, Vol. 96, No. 1,... 

PAN,C.H.T. Calculation of pressure, shear, and flow in lubrication films for high speed bearings, ASME Journal of Lubr. Tech., 1974, 96, No.l, 80-94. 

PB = length of contact p = pressure in lubricant film P = load per unit width... 

W HIRS. "A bulk flow theory for turbulence in Lubricant films", 3. of Lub. Tech.,... 

In lubricating films, lateral diffusion of momentum and heat is usually much less than transverse. Furthermore, inertia and pressure-energy effects are frequently negligible, and the transverse variation of pressure is small. Therefore, we adopt the following equations for laminar lubricating films. 

The growth of solid films onto solid substrates allows for the production of artificial stmctures that can be used for many purposes. For example, film growth is used to create pn junctions and metal-semiconductor contacts during semiconductor manufacture, and to produce catalytic surfaces with properties that are not found in any single material. Lubrication can be applied to solid surfaces by the appropriate growth of a solid lubricating film. Film growth is also... 

The often-cited Amontons law [101. 102] describes friction in tenns of a friction coefiBcient, which is, a priori, a material constant, independent of contact area or dynamic parameters, such as sliding velocity, temperature or load. We know today that all of these parameters can have a significant influence on the magnitude of the measured friction force, especially in thin-film and boundary-lubricated systems. 

Antiwear Compounds. Additives are used in many lubricating oils to reduce friction, wear, and scuffing and scoring under boundary lubrication conditions, ie, when fuU lubricating films cannot be maintained. Two general classes of materials are used to prevent metallic contact. 

The wide range of soHd lubricants can generally be classified as either inorganic compounds or organic polymers, both commonly used in a bonded coating on a matching substrate, plus chemical conversion coatings and metal films. Since solid-film lubricants often suffer from poor wear resistance and inabihty to self-heal any breaks in the film, search continues for improved compositions. 

Bonded Solid-Film Lubricants. Although a thin film of soHd lubricant that is burnished onto a wearing surface often is useful for break-in operations, over 95% are resin bonded for improved life and performance (62). Use of adhesive binders permits apphcations of coatings 5—20 p.m thick by spraying, dipping, or bmshing as dispersions in a volatile solvent. Some commonly used bonded lubricant films are Hsted in Table 12 (62) with a more extensive listing in Reference 61. 

Under severe conditions and at high temperatures, noble metal films may fail by oxidation of the substrate base metal through pores in the film. Improved life may be achieved by first imposing a harder noble metal film, eg, rhodium or platinum—iridium, on the substrate metal. For maximum adhesion, the metal of the intermediate film should ahoy both with the substrate metal and the soft noble-metal lubricating film. This sometimes requires more than one intermediate layer. For example, silver does not ahoy to steel and tends to lack adhesion. A flash of hard nickel bonds weh to the steel but the nickel tends to oxidize and should be coated with rhodium before applying shver of 1—5 p.m thickness. This triplex film then provides better adhesion and gready increased corrosion protection. 

Individual particle surfaces can be lubricated by an adsorbed film that produces a smoother surface and/or decreases interparticle attraction. A plasticized binder may serve this purpose. Forming surfaces can be lubricated by coating with a film of low viscosity Hquid such as water or oil. Die surfaces can also be coated with a solution of stearic acid dissolved in a volatile Hquid that rapidly evaporates to leave a lubricating film. 

Polybutenes enjoy extensive use as adhesives, caulks, sealants, and glaring compounds. They are used as plasticizers in mbber formulations with butyl mbber, SBR, and natural mbber. In linear low density polyethylene (LLDPE) blends they induce cling to stretch-wrap films. Polybutenes when modified at their unsaturated end groups with polar fiinctionahty are widely employed in lubricants as dispersants. Blends of polybutene with polyolefins produce semisoHd gels that can be used as potting and electrical cable filling materials. 

One of the major advantages of the worm gear is low wear, which is due mostly to a full-fluid lubricant film. In addition, friction can be further reduced using metals having low coefficients of friction. For example, the wheel is typically made of bronze and the worm of highly finished hardened steel. 

A variety of chemical additives can be incorporated in lubricating oils to improve their properties under boundary lubrication conditions. Some of these additives react with the surfaces to produce an extremely thin layer of solid lubricant, which helps to separate the surfaces and prevent seizure. Others improve the resistance of the oil film to the effect of pressure. 

---