摘要:

A model is developed for the stiction and deformation of laser textured disks with crater-shaped laser bumps. Stiction and laser bump deformation are investigated as a function of laser bump and head/disk design parameters. In addition, a Monte Carlo analysis is performed to numerically study the dependence of the stiction force on laser bump and head/disk, design parameters. The results from the model are in very good agreement with experimental data.Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982304

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The lubricating life of a grease in rolling element bearings is limited by operation at high temperatures. The thermal and mechanical stresses imposed result in gross physical and chemical changes to the grease which contribute, eventually, to failure both of the lubricant and the bearing. The problem is very complex as both grease and bearing parameters contribute to failure and these are difficult to disentangle. Most of the research work in this area has been with bearing tests where samples of bulk grease have been removed for analysis after failure. Although this approach will yield results as to grease life and the condition of the grease at the end of the test it provides little insight into the fundamental mechanisms of failure.

ISSN:1040-2004    

DOI:10.1080/10402000008982305

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Oil film thickness and traction characteristics of a polyol ester in some hydrofluoro carbon and hydrochlorofluoro carbon refrigerants are determined with an EHD tester, where increase in refrigerant gas pressure decreases film thickness as well as traction in each refrigerant. When compared under an identical gas pressure, the film thickness with refrigerant is R-125 > R-134a > R-22, while that for the coefficient of traction at a certain slide-roll ratio is the same as film thickness. Oil film formability and traction performance are inversely correlated with solubility of refrigerant in POE in mole concentration.

ISSN:1040-2004    

DOI:10.1080/10402000008982306

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Based on gear scuffing results obtained on a high speed gear test rig, equations for calculating bulk temperature as well as critical temperature of a lubricant/steel combination are presented for dip lubrication. The calculation for bulk temperature of gears is modified to include speed as well as applied load. Critical scuffing temperature, previously thought to be independent of operating conditions, is found to be greatly influenced by gear speed and oil type. Experiments show that synthetic oils increase the value of critical temperature dramatically in comparison with base mineral oils, and speed also alters the critical temperature. The curves of critical temperature vs. pitch line speed of gears are characterized by a parabolic shape which is verified experimentally and mathematically. The effect of speed is attributed to a chemical process in which the loss of reaction film is related with the length of time in the contact zone. The effect of oil type is explained by the strength and concentration of reaction films on the contacting surfaces. Finally, a modified equation is presented for converting scuffing load limit between simulated and practically used gears.

ISSN:1040-2004    

DOI:10.1080/10402000008982307

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this paper, Ni-based alloys with different addition amounts of mixed rare earth fluoride were prepared using a P/M method in an intermediate frequency inductive furnace. The effect of mixed rare earth fluoride (30.9 wt.% LaF3and 69.1 wt.% DyF3in composition) additions on the mechanical strength of the alloy was investigated and compared with that of a CeF3addition. The findings indicated that by adding 3 wt.% mixed rare earth fluorides the improved toughness can be obtained. By adding 3 wt.% and 5 wt.% of mixed rare earth fluorides the compressive strength at 700°C were increased. The friction and wear behavior of the composite sliding against a high temperature self-lubricating composite at room temperature and 600°C in air were investigated on a pin-on-disk tribometer. The composites showed better tribological performances at 600°C than at room temperature.

ISSN:1040-2004    

DOI:10.1080/10402000008982308

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Experimental results are presented that show relationships between grain structure and friction. In particular, grain boundaries cause changes in friction during single pass experiments using a diamond rip sliding on polycrystalline tungsten (polytungsten) and polycrystalline silicon (polysilicon). For polysilicon, the crystallographic orientation of individual grains is also shown to have n pronounced effect on friction. Since polysilicon is the major material used for microelectromechanical systems (MEMS), inter- and intragranular friction measurements are needed by scientists and engineers who hope to design and fabricate microminiature motors and other devicevs using polysilicon. For this reason, friction measurements were also made using an Atomic Force/Friction Force Microscope (AFM/FFM) which allows for measurements on a microscope.Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982309

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper describes measurements of the change in surface roughness of aluminium strip due to cold rolling. Rolling is in the mixed lubrication regime, where there is both asperity contact and hydrodynamic action. The strip is in the as-received condition before rolling, with a continuous spectrum of roughness wavelengths. The spectra of roughness for both the initial and rolled surfaces are used to extract amplitudes for long and short wavelength components, with an arbitrary division at a wavelength of 14 μm between these components. It is found that the short wavelength components persist more than the long wavelength components, and that flattening of the strip increases with reduction in strip thickness. The qualitative effect of wavelength on flattening is similar to that observed with unlubricated rolling (Sutcliffe, 1999), and is in line with theoretical models of mixed lubrication. The effect of reduction is not predicted by existing theories, but is in agreement with measured variations of friction with reduction.Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982310

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The effect of molybdenum dithiocarbamate (MoDTC) on the friction and wear properties between aluminum alloy and steel was investigated. Large adhesive wear of the aluminum alloy is caused by the transfer of aluminum to the steel when an oil without MoDTC is used. MoDTC can prevent the adhesive wear of aluminum alloy by generating a surface film in the higher sliding speed range. The surface film reduces specific wear of the aluminum alloy to less than approximately 10−9mm2·N−1, but increases that of the steel to 10−9mm2·N−1. The corrosive wear of the steel was apparently caused by sulfur originating from MoDTC.Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982311

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The effect of particles on lubricated friction in mixed to hydrodynamic lubrication regime is investigated by using the spherical alumina particles which size distribution is known. It is found that the particles increase friction and the effect disappeared at elevated velocities. The increase in friction is not linearly proportional to the particle concentration but tend to saturate at higher concentrations especially at lower velocities. To explain these major features of the particle effect, a model that the particles larger than the lubricating film interfere with the surfaces is employed. A linear relationship between the numbers of interfering particles and increase in friction is established by introducing a concept that is similar as dead time in pulse counting. Then interference condition is evaluated by means of the interference height, length and friction force generated by each particle. It is concluded that the most of the velocity dependence of the particle effect is caused by the reduction of the interference time and reduction in loads supported by the particles at elevated velocities.Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982312

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Reciprocating friction and wear tests of Al-Si alloy matrix composites in contact with bearing steel were conducted in air and lubricating oil to evaluate the friction and wear characteristics of the composites.

ISSN:1040-2004    

DOI:10.1080/10402000008982313

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor