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Carbon steel has a high application rate in modern industry, but this type of steel has the defect of high wear. This study aims to improve the surface friction and wear performance of carbon steel under such working conditions.

In this study, a dry film lubricant based on graphite powder was prepared by the ultrasonic dispersion method, and deposited on the surface of carbon steel specimens by the simple pressure spraying technology. At the same time, molybdenum disulfide and polytetrafluoroethylene dry film lubricants were developed by the same method, and the comparative experimental study on friction and wear was carried out in the end-face friction tester.

The results show that the deposition effect of graphite and molybdenum disulfide dry film lubricants on the surface of carbon steel is obviously better than that of polytetrafluoroethylene dry film lubricant. Compared with molybdenum disulfide and polytetrafluoroethylene dry film lubricant, graphite dry film lubricant has the best friction and wear performance on the surface of carbon steel. The working life of carbon steel specimens sprayed with graphite dry film lubricant decreases with the increase of pressure load and rotation speed. The combination of load and sliding speed will accelerate the transition of the coating to a stable direction. In addition, the micro lubricant particles formed in the wear process will form particle flow lubrication, and the appropriate addition of particle powder of the same material will also prolong the normal antifriction time of the lubricant.

These findings developed a dry film lubricant that can effectively improve the friction and wear properties of carbon steel surface.

To make a derivation of the load‐carrying capacity of elastohydrodynamic lubrication for special operating conditions, i.e. extremely heavy loads or extremely low rolling speeds based on the Newtonian fluid model by taking the Grubin‐type EHL inlet zone analysis, justify the load‐carrying capacity of elastohydrodynamic lubrication film in these operating conditions, and propose future trends of the research in EHL and mixed EHL based on the obtained results in the present paper.

A Grubin‐type EHL inlet zone analysis is carried out for the isothermal EHL of line contacts in special operating conditions, i.e. extremely heavy loads or extremely low rolling speeds based on the Newtonian fluid model. Comparison is made between the central EHL film thickness in line contacts, respectively, predicted by conventional EHL theories and accurately predicted from the present analysis for these operating conditions. An interpretation is made for the EHL film thickness in these operating conditions by taking the approach of the transportation and flow of the fluid through elastohydrodynamic contact when the EHL film is, respectively, thick and molecularly thin in the Hertzian zone. Conclusions are drawn on the load‐carrying capacity of EHL, EHL contact regimes and mixed EHL regimes in these operating conditions.

The present EHL inlet zone analysis shows that the EHL film thickness in the Hertzian zone is on the nanometer scale and the lubricant is non‐continuum across the film thickness in the Hertzian zone at relatively heavy loads in line contact EHL when the dimensionless rolling speed is lower than the dimensionless characteristic rolling speed U_ch=0.0372W^1.50/G. In this case, the central EHL film thickness in line contact EHL predicted by the conventional EHL theory may be several orders of magnitudes higher than that accurately predicted. This difference may be greater for heavier loads.The present results for line contact EHL based on the Newtonian fluid model show that in line contact EHL, for relatively heavy loads and the dimensionless rolling speed lower than the dimensionless characteristic rolling speed U_ch=0.0372W^1.50/G, the EHL analysis needs to further incorporate the lubricant non‐continuum effect across the film thickness in part of the lubricated area to investigate the EHL film thickness and the EHL film pressure in the contact in this very low film thickness condition; only the results based on such an analysis are believable for the EHL stage where the lubricant film thickness in the Hertzian zone approaches to zero and then vanishes; the results for EHL based on the Newtonian fluid model is unable to conclude that the EHL film thickness in the Hertzian zone is zero and dry contact occurs between the contact surfaces in EHL in any operating condition for ignoring the lubricant non‐continuum regime governing the EHL stage preceding the occurrence of the zero lubricant film thickness in EHL.

A very useful source of information for academic scientists, engineers and tribologists who are engaged in the study and application of the theory of elastohydrodynamic lubrication.

A derivation is first carried out for the isothermal EHL of line contacts in extremely heavy loads or extremely low rolling speeds by taking the Grubin‐type EHL inlet zone analysis by the present paper. Results and conclusions on the load‐carrying capacity of EHL in these operating conditions are first strict and thus convincing. These results are also original in clarifying the future trends of the researches in EHL and mixed EHL.

LONG before man learnt to make fire by the friction of wood, he experienced the burden of friction in dragging home his kill. Perhaps it is not too fanciful to suppose that the torn sides of his beast gave the first solid lubricant. Blood and mutton fat were seriously recommended as lubricants for church bell trunnions as recently as the 17th century. Indoed we still reckon fatty acids the best of all boundary lubricants. The range of man's activities has increased enormously in the present century, and particularly in the last few decades. Men have circled the earth in space; a space ship is on its way to examine another planet; terrestrial man is boring to the bottom of the earth's crust; others have descended to the depths of the ocean, and oven established a home on the floor of the Mediterranean, Speeds have increased by factors of thousands, temperatures range from near absolute zero to thousands of degrees; and a new environment of high‐intensity nuclear radiation has been created. Still, objects must move over and along each other in these exotic conditions; and to a large extent solid lubricants can provide the answer to the frictional problems.

THE VERY TITLE of this talk is something which is always quite exciting to an Engineer—that is the thought of completely dry lubrication and the possibility of dispensing with such unpleasant necessitites as grease cups, nipples, oil sumps etc. Unfortunately, films of dry lubricants do have co‐efficients of friction and are therefore subject to wear, so the ideal of “life time lubrication” is still in the far and distant future. However new materials are constantly being discovered and/or developed which offer some technical advantage over the previous best, and as each of these materials comes to light it does mean that there are a few more engineering units that at one time were dependent on grease or fluid film lubrication that may now be dry lubricated. It is really the technical‐cum‐commercial development of dry lubricants that this paper discusses. For many years the use of Lamellar solids was limited to such materials as talcum, mica and graphite, the last being by far the most popular and possibly still the most widely used today. In more recent years, molybdenum disulphide has come very much to the fore, and because of certain technical advantages (which will be discussed later) will probably replace graphite if and when it becomes more economical to produce and if it in turn does not first become replaced by other lubricating solids such as boron nitride, tungsten disulphide and cadmium oxide. Of these “new” names in dry lubrication, tungsten disulphide looks very promising and has been selected as the third dry lubricant to discuss.

CLAIMED to be able to carry loads as high as 1,800 lb/sq. in. with little self‐wear and negligible wear of the surfaces against which they are sliding, a new group of self‐lubricating materials have been developed by the Westinghouse Electric Co. in the U.S.A. They are metal based composites containing small percentages of a film former, called polytetrafluoroethylene, and a novel dry lubricant, called tungsten diselenide, and are available in both a silver and copper matrix which are totally and homogeneously impregnated with the dry lubricant and film former. The lubricant is held in small pockets throughout the metal or high polymer matrices and form dry films of self‐lubricating material on the metal surfaces rubbing against the composites. These dry films transfer to other metal surfaces as they come into rubbing contact with the coated metal surfaces. In this way, the film continually transfers back and forth to heal any tiny break or faults that may occur in the films.

THE Glacier Metal Co Ltd manufacturers three dry bearing materials, namely Glacier DU, DQ and Deva Metal.

The effects of space environment on friction and wear and on the selection of lubricants and self‐lubricating materials for spacecraft mechanisms are discussed, with special emphasis on the ultrahigh vacuum of space. Experimental studies have demonstrated the feasibility of using selected oils and greases to lubricate lightly loaded ball bearings without replenishment for periods of over one year under the following conditions of operation : speeds of 8,000 rpm, temperatures of 160 to 200°F., and vacuum of 10–8 torr. Over one‐half year of successful operation has been achieved under similar operating conditions with self‐lubricating retainers of reinforced Teflon, provided that the loads were light. Bonded films of molybdenum disulfide have given shorter lifetimes and poor repro‐ducibility. Metal‐to‐metal slip‐ring contacts introduce excessive electrical noise into circuits when operated in vacuum of 10–7 torr. The noise (as well as the friction and wear) can be markedly reduced by providing a small amount of oil vapor, sufficient to maintain a pressure on the order of 10–6 torr, or by incorporating molybdenum disulfide into the brush material.

LUBRICANTS capable of lubricating mechanisms intended for use in present and future missile satellite systems and spacecraft must provide long‐time operational reliability under a variety of earth and space environmental and operational conditions. For example, the lubricants will be exposed to conditions attendant to ground activities; to short‐time operations during the launch, ascent and re‐entry and to extended operations in orbit. Ground operations include exposure to test and check out procedures, handling and transportation, exposure to elements and to possible fuel or oxidizer spillage. Under launch, ascent, and re‐entry, the effects of heavy shock, severe vibration, high and low temperature, and possibly fuel and oxidizer exposure, may be expected. When in orbit, the lubricant must still provide satisfactory lubrication despite the effects of ultra‐high vacuum, zero gravity, temperature extremes, and radiation exposure. Add to these requirements the compatibility factor and some idea of the demands placed on aerospace lubricants may tend to take form. It is unlikely that any one lubricant, even of the solid film type will be applicable to all these conditions; therefore, it appears quite likely that the solid film will be individually tailored to each specific application. As will be noted further that the Denver Division of the Martin Company allows the use of three distinct type solid film dry lubricants. It is expected that more will be added when environmental testing proves reliable under a specific set of requirements.

DRAWING of metals occurs in innumerable ways, both hot and cold. Here, however, we are concerned only with the cold drawing operations used to form vast tonnages of steel, and large quantities of non‐ferrous metals, as tube and wire, and for the forming of sheet metals (especially by deep drawing).