摘要:

The Barus equation relating viscosity to pressure includes a pressure-viscosity coefficient used widely by investigators even though that coefficient is grossly inaccurate at elevated pressures. A new empirical equation was developed relating viscosity to pressure. The equation is mathematically simple and provides two coefficients that are satisfactory over a wide pressure range. These coefficients are temperature dependent and produce a pressure-viscosity relationship with a maximum error of only about 8 percent at a temperature of 37.8°C over a pressure range to 0.60 GPa for a number of fluids.

ISSN:0569-8197    

DOI:10.1080/05698198308981471

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

An investigation was made of the behavior of different ferrocenyl alcohols and ferrocenyl sulfides as wear-reducing additives in paraffin oil. From measurements of wear as determined by four-ball apparatus, and extensive examination of products being formed by the ferrocenyl alcohols during sliding, a carbocation model has been proposed which elucidates the mechanism of wear and seizure protection.

ISSN:0569-8197    

DOI:10.1080/05698198308981472

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The purpose of the paper has been to present a comparison of theoretically predicted and experimentally measured pressures between nearly cylindrical rollers. The primary theoretical and experimental tools have been described earlier, but have required some refinement to evaluate critical edge stress conditions. At misalignment levels on the order of 0.86 to 1.25 × 10−3radians, edge stresses on the order of 2 GPa have been measured and predicted. These stresses are more than twice the stresses that would occur for ideal line contact.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in New Orleans, Louisiana, October 5–7, 1981

ISSN:0569-8197    

DOI:10.1080/05698198308981473

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Friction measurements were performed on the ball-on-cylinder machine at a low sliding speed and high loads to establish conditions of isothermal boundary lubrication. Friction coefficients, as well as the topology of the wear tracks, were measured under different conditions of lubrication: dry contact in laboratory air, lubricated contact with puren-hexadecane, and a saturated (1 percent) solution of palmitic acid in hexadecane. Dry sliding produced a friction coefficient of 0.45 and wear characterized by heavy fissuring. The palmitic acid solution provided a low friction coefficient of 0.12 and a burnished, crack-free sliding track, as expected. When highly purifiedn-hexadecane was used as the lubricating medium, the recorded friction coefficient was as high as 0.75 but the sliding track was at first similar to that produced in 1 percent palmitic acid; wear occurs in the translation of elongated, thin platelets parallel to the surface. This mode of wear particle formation has apparently not been reported elsewhere and differs markedly from the protruding shear plates observed in dry sliding. It is concluded that the action of pure hexadecane is to redistribute part of the normal and shear loads to regions between those of metallic conjunction in the sliding contact. This redistribution of stresses prevents the occurrence of stress reversal fatigue and leads to reduced wear even if the friction coefficient is larger.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in New Orleans, Louisiana, October 5–7, 1981

ISSN:0569-8197    

DOI:10.1080/05698198308981474

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Antiwear additives are necessary components of motor oils in order to maintain satisfactory wear rates of automobile engines, particularly in the valve train area. Even though much has been accomplished to minimize wear, the processes by which antiwear additives function to mitigate wear are not completely known. A mechanism is proposed which includes antiwear additive—surface interaction by either adsorption followed by reaction or direct reaction. This mechanism is shown to be consistent with previous experimental data. Evidence is shown indicating that surface sulfide is not the sole species responsible for boundary lubrication with organosulfur compounds. The formation of sulfide rather than the thermodynamically preferred sulfate is indicated to be the result of kinetic limitations which restrict oxygen and produce a “reducing atmosphere” during reaction on the surface. A mechanism for producing wear debris is proposed. This mechanism relies on diffusion and segregation of antiwear additive elements into grain boundaries followed by subsequent fracture. This model is shown to be consistent with experimental observations.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in New Orleans, Louisiana, October 5–7, 1981

ISSN:0569-8197    

DOI:10.1080/05698198308981475

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A series of pure zinc dialkyldithiophosphates have been tested on high-frequency reciprocating test device. The formation of thick chemical films during friction testing was monitored using contact resistance measurements.

ISSN:0569-8197    

DOI:10.1080/05698198308981476

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

X-ray photoelectron and Auger electron spectroscopy analyses and tribological studies were conducted with a silicon carbide {0001} surface in sliding contact with iron at various temperature to 1500°C in a vacuum of 10 nPa. The results indicate that there is a significant temperature influence on both the friction properties and the surface chemistry of silicon carbide. Graphite and carbide-type carbon are seen primarily on the silicon carbide surface in addition to silicon at temperatures to 800°C. The coefficients of friction of iron sliding against a silicon carbide {0001} surface were high at temperatures to 800°C. When the friction experiments were conducted at temperature above 800°C, the coefficients of friction were dramatically lower. At 800°C, the silicon and carbide-type carbon are at a maximum intensity in the XPS spectra. With increasing temperature above 800°C, the concentrations of the graphite increase rapidly on the surface, whereas those of the carbide-type carbon and silicon decrease rapidly. This presence of graphite is accompanied by marked decrease in friction.

ISSN:0569-8197    

DOI:10.1080/05698198308981477

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The wear and friction behavior of compressed compacts of molybdenum disulfide was examined during sliding in air against a 0.45 percent carbon steel disk. The contact pressure was 0.082 through 0.412 MPa, and the sliding speed was 0.03 through 5.00 m/s. The specific wear rate (wear volume per unit sliding distance/load) under various experimental conditions was found to be a simple function of a parameter fPV, corresponding to the frictional heat. It was noted with interest that the wear of molybdenum disulfide compacts decreased when sliding conditions were made more severe.Presented as an American Society of Lubrication Engineers paper at the ASLEIASME Lubrication Conference In New Orleans, Loulsiana, October 5–7, 1981

ISSN:0569-8197    

DOI:10.1080/05698198308981478

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

For pure hydrodynamic conditions in instationary loaded journal bearings, the viscosity characterizes the behavior of lubricants. Whereas the viscosity of Newtonian fluids changes with temperature and pressure, non-Newtonian lubricants are also affected by shear rate. These physical effects are not constant in circumferential and axial direction of a journal bearing. They form a definite viscosity distribution, which will be permanently changed by the varying conditions of dynamically loaded bearings.

ISSN:0569-8197    

DOI:10.1080/05698198308981479

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A method for predicting the effects of lubricant chemistry on bearing fatigue life was evaluated. The method was based on a correlation that was developed from wear test data, obtained with a ring-on-black tester, and full-scale bearing life test data. The correlation revealed that the degree of wear was inversely proportional to bearing fatigue life. The relationship between wear and bearing life was developed by using both light- and heavy-viscosity base oils, single- and multicomponent-additive formulations, and various commercial lubricant formulations. It was concluded that the ring-on-block tester may represent a method for predicting the chemical effects of mineral oil formulations on bearing fatigue life. A lubricant chemical adjustment factor for predicting such effects was derived. The wear tester appeared to identify an important property of lubricants that should enhance the process of selecting lubricants for various applications. The data revealed that a small number of lubricants exerted a detrimental influence on fatigue life, but the majority of formulations tested were either indifferent to fatigue life or had a beneficial effect. This fact correlates well with the large-scale use of additives throughout industry where bearing performance is significantly enhanced. The findings indicate that the chemical influence of lubricants can be a significant factor for both wear and fatigue processes. A mechanism for explaining the correlation for wear and bearing life is discussed.Presented as an American Society of Lubrication Englneers paper at the ASLE/ASME Lubrlcatlon Conference In New Orleans, Loulslana, October 5–7, 1981

ISSN:0569-8197    

DOI:10.1080/05698198308981480

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor