Harold Ravner

Interactions in Neopentyl Polyol Ester—Tricresyl Phosphate—Iron Systems at 500 F

Neopentyl polyol esters, typical of turbine engine lubricant base stocks, are thermally stable at 500 F, unless, as reported by others, ferrous metals are present; in the latter case oil degradation and metal corrosion are severe. Tricresyl phosphate (TCP) stabilizes the metal-ester system by generating a passive oxide film on the active metal surface. In the presence of water, TCP accelerates ester hydrolysis, resulting in acids corrosive to lead. Aliphatic amines which react with TCP acidic impurities or breakdown products reduce the catalyzed hydrolysis of the esters. TCP reacts with free carboxylic acids to generate corrosive phosphoric-type acids. Reaction mechanisms are postulated. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Houston, Texas, October 14–16, 1969

High-Temperature Stabilization of Polyphenyl Ethers by Soluble Metal-Organic Salts

A series of soluble metal phenoxides prepared from two phenols was investigated as high-temperature (to 371 C) anti-oxidants in polyphenyl ether (5P4E). Compounds from Group 1A (alkalis) and 2A (alkaline earths) were effective, but not in the same order as their inorganic oxide, hydroxide and carbonate counterparts studied earlier. High-temperature antioxidant activity of the phenoxides was not adversely affected by water-saturated air; the phenoxides were, however, subject to hydrolysis at 40 C by persistent exposure to liquid water. The phenoxides did not adversely affect the pyrolytic stability of the ether in the absence of air, although they were themselves slightly degraded. Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

Inhibition of Iron-Catalyzed Neopentyl Polyol Ester Thermal Degradation Through Passivation of the Active Metal Surface by Tricresyl Phosphate

To investigate the role of tricresyl phosphate (TCP) in inhibiting the iron-catalyzed thermal degradation of a neopentyl polyol ester gas turbine lubricant base stock, various TCP/ester combinations were encapsulated in mild steel tubing and heated at 500 F up to 96 hours. The relative degradation rates of the individual mixtures were measured by monitoring the effusion site of hydrogen (a degradation byproduct) through the capsule all. The capsule interiors were then examined by electron microscopy and diffraction to determine whether correlation assisted between the features of the surface films formed and the reserved degradation rates. Distinctive films were produced in each test mixture. When ester degradation was inhibited by the addition of 2–10% TCP, characteristic iron oxide layer was always found at the ester/steel interface. It was postulated that TCP induces the formation of this film, that the film is the agency of inhibition, and that it is similar in action and genesis to the iron oxide pas...

High-Temperature Stabilization of Polyphenyl Ethers By Inorganic Salts

The free radical-induced high-temperature (to ca 370 C) oxidative degradation of polyphenyl ethers is shown to be drastically curtailed by the oxides, hydroxides and carbonates (but not the neutral salts) of the alkali metals and barium. The inhibiting entities form colloidal or molecularly soluble complexes with the ether, and function in very low concentrations. Mechanisms are proposed which invoke either the basicity of the effective salts, or their ability to destroy peroxy radicals via superoxide formation. Properly designed inhibitors of the types discussed are of interest in polyphenyl ether-based lubricants for very-high-output aircraft turbine engines. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Pittsburgh, Pennsylvania, October 5–7, 1971

Factors Contributing to the Properties of Fluoropolymer Barrier Films

Films of poly(1,1-dihydropentadecafluorooctyl methacrylate) (PFOMA) cast from fluorinated solvents are inert and not wetted by most organic liquids. They are widely used as barrier film in such applications as confining lubricants to miniature bearing raceways or preventing creep onto critical nonlubricated electric relay contact points. The quality of the films, e.g. thickness, surface texture, and resistance to liquid lubricants, is described in terms of their relation to the formulation variables of the PFOMA-solvent system. Aspects which contribute to optimization of the barrier film properties and the relevance of solvent thermodynamic properties are discussed. Presented at the 32nd Annual Meeting in Montreal, Quebec, Canada, May 9–12, 1977

Amine Phosphates as Antiwear Additives in Neopentyl Polyol Esters

Dialkyl acid phosphates are effective antiwear agents in neopentyl polyol ester lubricants applied to 440C stainless steel sliding surfaces at low loads, but they promote ester deterioration. Various amine salts of three representative dialkyl phosphates were studied to determine if the adverse effect could be reduced without sacrificing antiwear properties. The amine phosphates were generally highly effective in the low load region in four-ball wear tests. They were at least as effective as the parent acid phosphates and appreciably more effective than tricresyl phosphate. Little effect of amine structure on performance was observed. At a higher load, both the acid phosphates and their amine salts had no beneficial effect on wear. The amine phosphates promoted significantly less deterioration of the base ester under four-ball test conditions (266F) than did the dialkyl phosphates. In oxidation-corrosion tests at 3253, however, they were corrosive to copper and adversely affected ester stability. Presente...

Surface Analysis of Bearing Steels After Solvent Treatments

Traces of surface contaminants on precision miniature instrument bearings in guidance and other critical systems can greatly contribute to the ultimate failure of such systems. Current solvent-cleaning procedures employed by Navy facilities to prepare bearings for assembly vary with respect to materials and methods, but the specific effects of these variations on the bearing surfaces are unknown. To critically examine these effects, reference surfaces of specially cleaned 52100 and 440C bearing steels were characterized by Auger electron and X-ray photoelectron spectroscopic analysis, as well as by wettability and infrared studies, subjected to standard sequential cleaning cycles and to individual solvents at several Navy facilities, and re-examined by the same techniques. The data indicated that various quantities of hydrocarbon, ester and other residues were deposited on the reference surfaces during the cleaning process. The results are discussed in terms of comparison of the types, levels and probable...

Lubricants from Mixed Pentaerythritol Esters of 2-Ethylhexanoic and Isostearic Acids

A mixed pentaerythritol ester composed of 25 mole percent 2-ethylhexanoic and 75 mole percent of isostearic acid substituents was synthesized and characterized. By means of the synthetic and analytical procedures developed, this mixed ester can be prepared in a highly reproducible manner. Oxidation and thermal stabilities, corrosivity, and wetting characteristics are reported. The ester is of interest in instrument and bearing applications where a viscous lubricant having excellent low-temperature properties is required. Presented at the 26th ASLE Annual Meeting in Boston, Massachusetts, May 3—6, 1971

Factors Affecting Oxidation Stability of a Deuterated Ester

The significantly higher oxidation stability obtained on deuteration of the acid moiety of a neopentyl polyol ester is the result of two effects, viz, the deuteration effect and the synergistic effect of alkali metal compounds with the antioxidant. The enhancement in oxidation stability attributable to 96 atom percent deuteration appears to be three-to-fourfold at 220°C. The enhancement due to the alkali metal effect appears to be about thirtyfold. Preliminary results indicate that at higher deuterium concentration levels (>96 atom percent), the oxidative stability of the ester, deuterated on the acid moiety, is further increased. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in Hartford, Connecticut, October 18–20, 1983