David J. Boes

Friction-Wear Characteristics of Self-Lubricating Composites Developed for Vacuum Service

The friction-wear characteristics in air and in vacuum are reported for a group of composites that have recently been developed for ultra high vacuum service. They have demonstrated their ability to carry loads of 1400 psi with low self-wear and negligible wear of the surfaces against which they slide. These composites, made up of polytetrafluoroethylene (PTFE) and a solid lubricant distributed throughout a metal matrix, have been utilized as self-lubricating components in ball bearings operating in environments that conventional lubricants cannot tolerate. These environments include high vacuum (10−8 torr) and temperatures from -180 to 400 F. Contributed by the ASLE Technical Committee on Bearings and Bearing Lubrication and presented at the Annual Meeting of the American Society of Lubrication Engineers held in New York, April, 1963.

Unique Solid Lubricating Materials for High Temperature-Air Applications

A technique has been developed, whereby mechanical strength and excellent oxidation resistance is imparted to self-lubricating bodies of high lubricant content. By an “amalgamation” of powdered solid lubricants, such as tungsten diselenide, with a gallium alloy, followed by a subsequent compression-curing cycle, self-lubricating surfaces have been formed that resist oxidation at a temperature of 1500 F. This paper presents friction-wear characteristics of these materials at temperatures to 950 F. They offer potential as load-bearing surfaces and seals in high temperature applications for both oxidizing and inert or vacuum environment. Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

New Solid Lubricants: Their Preparations, Properties and Potential for Aerospace Applications

A group of compounds are described whose physical and chemical properties make them attractive solid lubricant candidates for aerospace applications. The compounds are diehalcogenides of the Group VB and VIB metals niobium, tantalum, molybdenum and tungsten. Through a description and discussion of their frictional characteristics and other pertinent properties, the potentials that they possess for applications in unusual environments are illustrated.

Chemical Interactions Involved in the Formation of Oxidation-Resistant Solid Lubricant Composites

Solid lubricating compacts of tungsten diselenide-gallium alloys are currently under development for use as self-lubricating members in high speed-high temperature ball bearing systems. The material is of considerable interest due to the fact that it resists oxidation at temperatures three times higher than pure tungsten diselenide. This paper discusses initial studies of the physical and chemical changes that occur in these compacts during a heal-treating cycle required in their fabrication. Speculations regarding the mechanism responsible for their oxidation resistance are presented. Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

A Dynamic Oxidation Test to Evaluate Grease Performance at High Temperatures

An instrument to evaluate grease or ball bearing performance at high temperatures under actual operating conditions has been developed. Operation of the bearing in an oxygen atmosphere has considerably reduced the total testing time required. By measuring the rate of oxygen consumption during a test, data on the chemical changes taking place in the grease are obtained, and the time of grease failure can be pinpointed quite accurately and reproducibly. Typical oxygen consumption curves of various greases, as well as data which show the effect of the internal bearing clearance and the bearings ABEC classification on grease life, are included. Contributed by the ASLE Technical Committee on Bearings and Bearing Lubrication and presented at the Annual Meeting of the American Society of Lubrication Engineers held in Detroit, Michigan, April 1957.

The Solubility of Helium in Various Lubricating Oils at High Temperatures and Pressures

The helium solubility characteristics of six low-viscosity lubricating oils have been investigated; namely, diester, aryl phosphate ester, dimethyl silicone, methyl phenyl silicone, paraffin base oil, and aromatic base oil. Solubility measurements were made over a 1000 psi pressure range and a 350 F temperature range. Results show that the solubility of helium in all fluids studied increases linearly not only with pressure but also with temperature. All fluids except the silicones exhibited heavy foaming tendencies upon decompression. Contributed to the American Society of Lubrication Engineers by the author.

The Performance of Lubricated and Dry Ball Bearings at 450 F in Oxidizing and Inert Atmospheres at Various Pressures

The performance of grease lubricated and unlubricated ball bearings has been examined under various conditions of atmosphere and pressure. Data showing the effect on bearing life by the substitution of “self-lubricating” retainers for standard metallic cages are also included. The tests were run in atmospheres of oxygen, nitrogen, and air, at pressures from 0.5–1 mm Hg absolute to 33 inches Hg, The majority of tests were conducted at 232 C. A general theory of bearing failure is proposed to explain the rather large variations in lubricant and bearing life brought about by the changes in the environment in which they operate. Contributed to the American Society of Lubrication Engineers by the author.