摘要:

Sliding friction between an 1/8 in. spherical steel rider and a gold-plated steel flat was measured for various loads (200–2000 gm), gold film thicknesses (0.1–10 μ) and steel combinations (440C and 52100). Coefficient of friction recorded in each run for 100 traverses was found to be most sensitive to the rider material (0.1–0.3 with 440C rider and 0.1–0.6 with 52100 rider, as compared to 0.6–0.7 for unlubricated steel). With a 52100 rider, as the number of traverses increase three distinct types of frictional behaviors were found: (A) slowly decreasing, (B) rapidly decreasing, and (C) increasing (sometimes a minimum was first reached). Theoretical coefficient of friction (0.1) was only observed with 'Type B' results. With a chromium rich 440C rider, friction was always low presumably due to its low affinity to gold.Presented as an American Society of Lubrication Engineers Paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972171

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Friction, wear and metal transfer of the silver-iron friction couple have been studied as a function of oxygen percentage of the surrounding atmosphere at different levels of temperature. The results show that the replacement of high purity argon by a mixture of argon and oxygen causes an instantaneous increase in friction, followed by local transfer of silver to the iron surface and a high rate of wear. The observed effect is reversible. It is found that in the severe wear region the diffusion of oxygen towards the friction interface determines the wear rate, although visible oxidation does not occur. Experimental evidence strongly suggests that the formation of thin films of iron oxide is responsible for increased adhesion and metal transfer.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972172

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Friction experiments were conducted in vacuum with outgassed surfaces. Experiments were made with single and polycrystalline Al2O3, sliding on themselves and in contact with metals at a sliding velocity of 0.013 cm per second, at loads to 1500 gm, temperatures to 575 C and ambient pressures to 10−10mm Hg. These studies were made with a hemispherical or spherical rider sliding on the flat of a rotating disk. The results of the investigation indicate that (a) the friction characteristics of sapphire sliding on sapphire is highly anisotropic, (b) with metals sliding on sapphire, fracture in sapphire occurs while with polycrystalline Al2O3shear occurs in the metal, and (c) hexagonal metals exhibited lower friction co-efficients than cubic metals in contact with polycrystalline Al2O3.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972173

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

The degree of cold welding in ultra-high vacuum (10−9torr) was determined for 45 metal combinations. Static coefficients of friction were measured after stationary contact under 9.2-lb load for 300 hours at 200 C. Kinetic coefficients were measured at a velocity of 0.4 inch/second immediately after breakaway. Nearly all of the metal combinations tested exhibited maximum kinetic coefficients higher than the corresponding static coefficients. Metal transfer was from rider to ring when the rider was softer but followed no pattern when the ring was softer. Very little correlation was found between the friction characteristics of the metals and their physical properties.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis. Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972174

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Experiments are described in which pins of low-alloy, medium-carbon steel are worn against disks of the same material under unlubricated sliding conditions. The friction and wear characteristics of this system are measured as functions of load and speed. The choice of loads and speeds was made in such a way as to obtain the entire range of “hot-spot” temperatures possible for the system. The results are then compared with those to be expected from a model of the wear process in which the wear at the contacting regions between the pin and the disk is closely associated with the oxidation of the metal in these regions. The temperature of oxidation is assumed to be the calculated “hot-spot” temperature. In order to make the results compatible with the proposed model, it is necessary to introduce a new parameter (having the dimensions of length) which is shown to increase steeply with increasing “hot-spot” temperature up to about 700 C. It then levels off, at about 10−6cm, for all hot-spot temperatures in excess of about 700 C. In this way, the hot-spot temperature is shown to be a very important variable in the wear of steel.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972175

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

This is a theoretical paper concerned with the rise in the surface temperatures caused by frictional heating at sliding contacts. By taking into account in the theoretical model, the growth of junctions between contacting asperities due to the action of the friction force, a large improvement in the correlation with experimental surface temperature measurements at dry friction contacts has been obtained. These results are felt to support the use of the usual flash temperature technique for predicting the surface temperatures in lubricated or low friction conditions.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972176

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

This paper is one of a series dealing with the surface temperature conditions in disks and gears. It attempts to apply and extend the theory proposed in an earlier paper which predicted the behavior of the surface temperature of machine elements subjected to repeated frictional contacts. In considering the critical temperature hypothesis proposed by Blok as a criterion for failure by scuffing, it is essential that the operating surface temperature is taken into account in addition to the well known “flash temperature.” There have been many papers referrinq to this “flash temperature,” but little is known of the factors which affect the operating surface temperature, commonly called the bulk temperature. This paper demonstrates that the bulk temperature growth under loaded conditions can be predicted theoretically, and that by observing the behavior of the surface temperature the heat transfer coefficient and friction conditions can be calculated. Finally full details of the thermocouple used by the authors in their tests are given.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972177

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Experiments were conducted to determine the effect of vibration on friction. A rider, consisting of three fixed 1/3-inch diameter balls, slid along a flat steel plate under a dead weight load of 1 kg and a speed of 0.02 cm/second. The plate was vibrated by a speaker at frequencies of 20, 100, 500, and 1000 cycles per second. Acceleration, coefficient of friction, and electrical resistance of a contact were measured. For both lubricated (white oil plus oleic acid) and unlubricated conditions, apparent kinetic friction decreased rapidly after the acceleration of vibration approached and exceeded the acceleration due to gravity. Electrical resistance increased periodically with vibration. The data indicated that the vibration periodically reduced metal-to-metal contact due to reduced load. Thus, an apparent reduction of the coefficient of friction was observed. Microscopic observation of the unlubricated wear tracks on the plate showed absence of galling, brown film formation, and marked plastic deformation during sliding with vibration. The possibility of fretting-type oxide film was considered.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis. Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972178

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

A study of an optical and two stylus-type instruments for measuring surface finish was conducted. The stylus-type instruments are demonstrated to be inaccurate on metals that have a Rockwell hardness less than C-66. The inaccuracy is attributed primarily to surface damage caused by the stylus. The optical instrument causes no surface damage. Stylus-type instruments are proven also to be unsatisfactory for rating relative degree of roughness unless gross roughness differences are considered.

ISSN:0569-8197    

DOI:10.1080/05698196708972179

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Using an automobile gasoline engine (73 mm bore × 71 mm stroke), temperatures of crankpin bearing and other related parts were measured by thermocouples. The thermocouple wires were led out from the crankpin bearing through the connecting rod, the pistonpin, the piston, the combustion chamber and the cylinder head. A better understanding of the behavior of crankpin bearings has resulted.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

ISSN:0569-8197    

DOI:10.1080/05698196708972180

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor