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Fluoride solid lubricants for extreme temperatures and corrosive environments
LITEKATUKE
404 certain sufficiently high deformation rate (usually above 10~ see-1) greases become practically Newtonian liquids m the process of flow, their viscosities being not much above that of the dispersion media. Fundamental Aspects of Grease Bleeding. S. F. Calhoun, NLGI Spokesman, q (IO) (1966)
328-332.
In this paper, the author concludes that better homogenization and dispersion of the grease thickener in the liquid component will increase both of the oil-retaining forces, and thus reduce bleeding. The Effect of Variations in the Viscosity and Type of the Mineral-oil Component on the Permeability Coefficients of Lithium-Calcium and Baragel Greases. J. L. Zakin and E. H. Tu, XLGI Spokesman, 29 (ro) (1966) 333-337. 3.3. Solid lubricants Preferential Adsorption of Compound8 with Long Methylene Chains on Cast Iron, Graphite, Boron Nitride, and Molybdenum Disulfide. A. J. Groszek, ASLE Trans., 9 (1966) 67-76. Several layered solids, which are effective solid lubricants, have a strong affinity for methylene groups. This leads to preferential adsorption on the solids of those paraffinic molecules that can form the maximum number of contacts with the surface and with each other. Thus the strength of adsorption of mineral oils increases with their average molecular weight. The strong affinity of the surfaces of the solid lubricants and cast iron for paraffine hydrocarbon is expected to influence their loadcarrying capacity, in that it should be higher for the oleophilic sliding surfaces than for surfaces such as those of plain steel, which are devoid of this property. So far, however, this has not been confirmed experimentally. For MoSz dispersed in mineral oils, indications have been obtained that the strong attachment of oil molecules to the surfaces of the dispersed solid reduces its EP effectiveness. Friction and Wear of Graphite and Molybdenum Disulphide. E. R. Braithwaite, Sci. Lubrication, 18 (4) (1966) 13, Part I; ibid., 18 (5) (1966) 17. Part 2; 16 figs., 4 tables, 23 refs. Part I : Experimental evidence for, and hypotheses on, the influence of adsorption of vapours on friction and the significance of intercrystalline forces, are presented. Part 2: Evidence of contact lubrication is given. The Effects of Reactor Radiation on Three High-temperature Solid-f&n Lubricants. R. H. McDaniel, Lubrication Eng., 21 (II) Wear, 9 (1966)
398-409
ANT) CUKKEN’f
EVEXI’S
463-473; I I figs., 7 tables, II refs. Experiments were performed to tleterminc the effects of reactor radiation on the wear life of three high-temperature, solid-film lubricant-PbS + MOSS I- BgOB, CaFy .i oxide frit, and MoSe + graphite + sodium silicate. Test specimens were irradiated under static conditions to an average gamma dose of 2.2 x loll ergs/g (C) plus associated neutrons of 5.2 x 1016 n/cm2 (E > 2.9 Me\‘). Subsequent tests with a double-rub, shoetype, sliding-wear tester were made with a load of IIO lb. per rub shoe and at a sliding speed of 128 ft./min. Tests were performed at several temperatures up to 1500’F. Based on the data obtained in this experiment and the statistical treatment employed (Weibull plots and ranking of data), it was concluded that static exposure to reactor radiation had no significant effect on the wear life of the PbS + MO& $ Hz03 film nor on the CaFz coating. The MO& + graphite 1~ sodium silicate film suffered a decrease in wear life at 80”F, but it displayed improved wear life at (loooF and izoo°F after irradiation. (1965)
Fluoride Solid Lubricant8 for Extreme Temperature8 and Corrosive Environments. H. E. Sliney, Th. N. Strom and G. P. Allen, ASLE Trans., 8 (1965) 307-322. Fluorides of the alkali metals and the alkalineearth metals have an interesting combination of properties that make them promising candidates as solid lubricant materials for use at high temperatures and in corrosive environments. They are chemically inert in strong oxidizing or reducing environments; they are relatively soft and non-abrasive; and some of them, such as CaF2, have planes of perfect cleavage in their crystal structure suggesting low shear strength and good friction properties. Thin, fused fluoride coatings (0.001 inch) were applied to nickel chromium alloys by spraying water slurries of the fluorides on the bearing surface, drying it, then firing it in a hydrogen atmosphere. Coatings of CaFz-LiF mixtures and of CaFz-BaFs mixtures were effective as solid lubricants in hydrogen to 1500°F and in air to 1200’F. The CaFs-BaFz coatings were effective solid lubricants in liquid sodium at 1000°F and a sliding velocity of sooo ft./min. Vapor-deposited, Thin Gold Films as Lubricants in Vacuum (lo-” mm Hg). T. Spalvins and D. H. Buckley, XASA Th-D-3040.
(1965)
13 PP.
Thin gold films were vapor-deposited on nickel, nickel-chromium, and nickel-rhenium surfaces to be used for lubrication purposes. The durability of the film was determined by friction characteristics. Durability and strong bonding (adhesion) between the film and the substrate are essential when thin
404 certain sufficiently high deformation rate (usually above 10~ see-1) greases become practically Newtonian liquids m the process of flow, their viscosities being not much above that of the dispersion media. Fundamental Aspects of Grease Bleeding. S. F. Calhoun, NLGI Spokesman, q (IO) (1966)
328-332.
In this paper, the author concludes that better homogenization and dispersion of the grease thickener in the liquid component will increase both of the oil-retaining forces, and thus reduce bleeding. The Effect of Variations in the Viscosity and Type of the Mineral-oil Component on the Permeability Coefficients of Lithium-Calcium and Baragel Greases. J. L. Zakin and E. H. Tu, XLGI Spokesman, 29 (ro) (1966) 333-337. 3.3. Solid lubricants Preferential Adsorption of Compound8 with Long Methylene Chains on Cast Iron, Graphite, Boron Nitride, and Molybdenum Disulfide. A. J. Groszek, ASLE Trans., 9 (1966) 67-76. Several layered solids, which are effective solid lubricants, have a strong affinity for methylene groups. This leads to preferential adsorption on the solids of those paraffinic molecules that can form the maximum number of contacts with the surface and with each other. Thus the strength of adsorption of mineral oils increases with their average molecular weight. The strong affinity of the surfaces of the solid lubricants and cast iron for paraffine hydrocarbon is expected to influence their loadcarrying capacity, in that it should be higher for the oleophilic sliding surfaces than for surfaces such as those of plain steel, which are devoid of this property. So far, however, this has not been confirmed experimentally. For MoSz dispersed in mineral oils, indications have been obtained that the strong attachment of oil molecules to the surfaces of the dispersed solid reduces its EP effectiveness. Friction and Wear of Graphite and Molybdenum Disulphide. E. R. Braithwaite, Sci. Lubrication, 18 (4) (1966) 13, Part I; ibid., 18 (5) (1966) 17. Part 2; 16 figs., 4 tables, 23 refs. Part I : Experimental evidence for, and hypotheses on, the influence of adsorption of vapours on friction and the significance of intercrystalline forces, are presented. Part 2: Evidence of contact lubrication is given. The Effects of Reactor Radiation on Three High-temperature Solid-f&n Lubricants. R. H. McDaniel, Lubrication Eng., 21 (II) Wear, 9 (1966)
398-409
ANT) CUKKEN’f
EVEXI’S
463-473; I I figs., 7 tables, II refs. Experiments were performed to tleterminc the effects of reactor radiation on the wear life of three high-temperature, solid-film lubricant-PbS + MOSS I- BgOB, CaFy .i oxide frit, and MoSe + graphite + sodium silicate. Test specimens were irradiated under static conditions to an average gamma dose of 2.2 x loll ergs/g (C) plus associated neutrons of 5.2 x 1016 n/cm2 (E > 2.9 Me\‘). Subsequent tests with a double-rub, shoetype, sliding-wear tester were made with a load of IIO lb. per rub shoe and at a sliding speed of 128 ft./min. Tests were performed at several temperatures up to 1500’F. Based on the data obtained in this experiment and the statistical treatment employed (Weibull plots and ranking of data), it was concluded that static exposure to reactor radiation had no significant effect on the wear life of the PbS + MO& $ Hz03 film nor on the CaFz coating. The MO& + graphite 1~ sodium silicate film suffered a decrease in wear life at 80”F, but it displayed improved wear life at (loooF and izoo°F after irradiation. (1965)
Fluoride Solid Lubricant8 for Extreme Temperature8 and Corrosive Environments. H. E. Sliney, Th. N. Strom and G. P. Allen, ASLE Trans., 8 (1965) 307-322. Fluorides of the alkali metals and the alkalineearth metals have an interesting combination of properties that make them promising candidates as solid lubricant materials for use at high temperatures and in corrosive environments. They are chemically inert in strong oxidizing or reducing environments; they are relatively soft and non-abrasive; and some of them, such as CaF2, have planes of perfect cleavage in their crystal structure suggesting low shear strength and good friction properties. Thin, fused fluoride coatings (0.001 inch) were applied to nickel chromium alloys by spraying water slurries of the fluorides on the bearing surface, drying it, then firing it in a hydrogen atmosphere. Coatings of CaFz-LiF mixtures and of CaFz-BaFs mixtures were effective as solid lubricants in hydrogen to 1500°F and in air to 1200’F. The CaFs-BaFz coatings were effective solid lubricants in liquid sodium at 1000°F and a sliding velocity of sooo ft./min. Vapor-deposited, Thin Gold Films as Lubricants in Vacuum (lo-” mm Hg). T. Spalvins and D. H. Buckley, XASA Th-D-3040.
(1965)
13 PP.
Thin gold films were vapor-deposited on nickel, nickel-chromium, and nickel-rhenium surfaces to be used for lubrication purposes. The durability of the film was determined by friction characteristics. Durability and strong bonding (adhesion) between the film and the substrate are essential when thin