摘要:

Value train wear was examined in a motored 2.3 l engine similar to that wed in the Sequence V-D test. A procedure was developed in which model hydroperoxides were added to the crankcase oil to simulate used oil. Cam lobe and follower wear occurred, apparently as a result of direct attack by the hydroperoxides on rubbing surfaces rather than through oil oxidation. The extent of wear was proportional to the hydroperoxide concentration. The same type of hydro-peroxide-induced wear subsequently was identified in a fired bench engine and in a field test.

ISSN:0569-8197    

DOI:10.1080/05698198708981775

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The present paper expounds on the effect of a near-surface cavity, when the solid surface is subjected to the Coulomb frictional loading of an asperity moving at moderately high speed. The medium under consideration is represented by a solid half-space which is coaled with a thin layer of solid wear coating. The cavity is assumed to be rectangular in cross section. The temperature field and its gradient in the vicinity of the cavity are obtained during the traverse of the asperity over the surface near the cavity. The cavity defect results in a material nonuniformity mathematically modelled in term of the material coordinates. The resulting governing differential equation is time-explicit and transient. A general finite difference formulation is developed, from which numerical solutions are obtained for problem with a cavity at various positions relative to the surface-layer/substrate interface. Because of the poor heat transfer characteristics of tile cavity, the temperatures in the surface layer above it are higher than those in the surrounding region. This phenomenon causes a higher temperature gradient, especially at the trailing corner of the rectangular cavity. There, the direction of the maximum temperature gradient is at a significant oblique angle to the wear surface. The combined effect of a higher temperature gradient and an oblique direction would result in a much larger shear stress in the surface-layer/substrate interface. This phenomenon could lead toward delamination of the coating near the cavity.Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Tribology Conference in Pittsburgh, Pennsylvania, October 20–22, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981776

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An AC impedance technique in combination with a thin-film (12 μm) cell was employed to separately meusure the electrical resistance and capacitance of electrode-lubricant interfaces and bulk lubricant layers. In this study, three different additives were investigated by measuring the AC impedance spectrum of each additive mixed separately with a commercially available mineral oil. These additives were oleic acid, N-oleyl-1,3 diaminopropane (fatty amine), and mixed alkyl acid orthophosphute (acid phosphate). For lubricants containing 2 mass percent of an acid phosphate or fatty amine, the capacitance of the electrode-lubricant interface, Ci, and the capacitance and resistance of the bulk lubricant layer, Coand Ro, respectively, were evaluated separately from the AC impedance spectra. The lower limit of the resistance of the electrode-lubricant interface, Ri, was aDo estivnated. For additives, such as oleic acid, which physically adsorbs on the electrodes, the resistance and capacitance of the electrode-lubricant interface and the bulk lubricant layer could not be measured separately.Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Tribology Conference in Pittsburgh, Pennsylvania, October 20–22, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981777

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Quantitative estimation of friction losses in the initial design stage of an automobile engine is a crucial issue that determines the fuel economy and performance of the automobile. However, measurements and mathematical treatments of friction losses were difficult, and practical estimation methods were scarce.

ISSN:0569-8197    

DOI:10.1080/05698198708981778

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The analysis in this Paper is concerned with the piezoviscous-rigid regime of lubrication for the general case of elliptical contacts. In this regime, several, formulas of the lubricant film thickness have been proposed. However, either the load parameter W is not included, which has a strong effect on film thickness, or the film thickness is overestimated by using the Barus formula for pressure viscosity characteristics. In the current study, the Roelands formula has been used for the pressure-viscosity relationship. The effects of the dimensionless load, speed, and materials parameters, the radius ratio, and the lubricant entrainment direction have been investigated. Forty-one cases were used in obtaining the minimum film thickness formula: H0= 178G0.386U1.266W−0.880(1 − e−0.0387αContour Plots indicate in detail the pressure developed between the contacting solids.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6—9, 1985

ISSN:0569-8197    

DOI:10.1080/05698198708981779

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Using high-speed steels T–1 cold M–50, which have little amount of retained austenite and the usual through-hardening ball bearing steel SUJ 2 (SAE 52100) previously tested, changes in x-ray parameters with loading cycles in rolling contact were examined and the following formula between loading cycles and x-ray parameters was found: N = K·(δB)6·(δσ)3·(δγ)0, where F = (δB)6·(δσ)3was defined as “fatigue parameter” and δB δσ, δγ are changes in half-height breadth, residual stress, and retained austenite, respectively. If we know in advance the value of Fc, the fatigue parameter at which a surface-originated fatigue failure results, the ratio of F at a given number of loading cycles to Fc gives the life ratio N/Nc, which is the ratio of loading cycles N to the loading cycles Nc when a surface originated fatigue failure would occur. Fc was about 1 for various materials and test conditions, if we use units of residual stress value in GPa and half-height breadth in degree of diffraction angle.Presented at the 42nd Annual Meeting in Anaheim, California May 11—14, 1987

ISSN:0569-8197    

DOI:10.1080/05698198708981780

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The paper presents a method to evaluate, the heat of adsorption of a two-component lubricant on the metallic surfaces in relative motion. The information needed to determine the heat of adsorption can be obtained by friction and wear measurements under boundary lubrication conditions.

ISSN:0569-8197    

DOI:10.1080/05698198708981781

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A secondary-alkyl zinc dialkyldithiophosphate (ZDP) was thermally decomposed in the presence of air. The resulting precipitate, when blended in a base grease, demonstrated better antiwear performance in a 4-ball wear machine than the parent additive. When extracted with acetone, a white powder with excellent antiwear properties was obtained from the precipitate. Chemical analysis indicated that this white powder was approximately 86 mass percent zinc pyrophosphate, 11 mass percent zinc orthophosphate, and 3 mass percent of an unknown sulfur compound. The antiwear effectiveness of a commercial zinc pyrophosphate and a zinc orthophosphate was also measured, but neither provided comparable antiwear protection. The white powder was amorphous/microcrystalline, whereas the commercial zinc pyrophosphate and zinc pyrophosphate were highly crystalline. These results indicate that zinc pyrophosphate is one of the thermal degradation products of ZDP. In addition, zinc pyrophosphate is suspected of being primarily responsible for ZDP's antiwear properties. The degree of amorphism/microcrystallinity may be a critical property for good antiwear performance of zinc pyrophosphates.Presented at the 42nd Annual Meeting in Anaheim, California May 11–14, 1987

ISSN:0569-8197    

DOI:10.1080/05698198708981782

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A numerical solution of an isothermal elastohydrodynamic contact, between two infinitely long waved surface cylinders, is presented.

ISSN:0569-8197    

DOI:10.1080/05698198708981783

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The mechanism of boundary lubrication of organic disulfides in while oil, using four-ball test data, has been studied by examining the influence of load, wear test time, concentration and structure. The amounts of iron sulfide, thiol and elemental sulfur fanned from disulfides have been quantitatively determined in oil solution and wear debris. Monosulfide was identified in oil solution after wear test. Temperature in wear junction and additive concentration in oil control the rate and magnitude of sulfur products formation. The formation of iron sulfide occurs by decomposition of disulfide to elemental sulfur and thiol, which than read with the metal surface giving sulfide. The separate chemical reaction paths of disulfides with different rates and amounts of sulfur products formation depended on the lubrication conditions present. The chemical structure of disulfides influences the formation of determined sulfur compounds.Presented at the 42nd Annual Meeting in Anaheim, California May 11–14, 1987

ISSN:0569-8197    

DOI:10.1080/05698198708981784

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor