摘要:

In some high-temperature applications, it is desirable to deliver the lubricant as a thin liquid film without recirculation. For these conditions, the buildup of the deposit on the hot surfaces outside the actual bearing contact area can be a problem. In this study, a mathematical model is developed which incorporates several chemical and physical processes which are taking place when a thin liquid film of lubricant is converted to a deposit at elevated temperatures. Specifically, the model utilizes kinetic studies of the degradation of tricresyl phosphate and the evaporation of this lubricant at modest temperatures, <280°C, and modest levels of TCP degradation to predict the final or terminal amount of deposit which will be produced over a broad range of temperature. The key to this model is incorporating the influence of the evaporation of the liquid lubricant on the diffusion of oxygen in the gas phase. The diffusion of the evaporated lubricant molecules away from the liquid phase inhibits the diffusion of the oxygen in the gas phase. Consequently, the oxidation of the liquid lubricant is significantly reduced by the unavailability of oxygen even when the liquid film is exposed to a moving stream of air.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983280

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A new technique was developed to deposit phosphate films on irregular shaped iron or steel components. This technique is a chemical process, and it does not need any external power supply. The phosphate films thus coated are beneficial in reducing both friction and wear. Co-deposition of copper and zinc along with the phosphate is also demonstrated. This process could lead to the tailoring of the friction and wear properties of coatings by introducing various metals. In addition, the co-deposition of copper and zinc demonstrates that the lubricant can serve as a medium for the transport of ionic species.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983281

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The influence, of environments on the properties of the surface films formed, with molybdenum dithiocarbamate (MoDTC) was examined under a reciprocating sliding condition. MoS2was formed on the rubbing surfaces in air and oxygen, and molybdenum compounds with an oxidation state lower than MoS2were produced in nitrogen and argon. The surface film composed of MoS2was effective in reducing the friction and wear, while the molybdenum compound formed in nitrogen or argon had no ability to prevent direct contact between the rubbing surfaces and to reduce the friction. It was a necessary condition for forming the surface film composed of MoS2that the environment to be rubbed contained oxygen at a concentration above a certain level.

ISSN:1040-2004    

DOI:10.1080/10402009408983282

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An electronically-controlled mechanical seal, for use as the purge gas seal in a liquid oxygen turbopump, has been designed, analyzed, and built. The thickness of the lubricating film between the faces is controlled by adjusting the coning of the carbon face. This is done by applying a voltage across a piezoelectric element to which the carbon face is bonded. Steady state tests have shown that the leakage rate (and film thickness) can be adjusted over a substantial range, utilizing the available range of voltage.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983283

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Wear and degradation as exhibited by degassing of three commercially available perfluoroalkylpolyethers, A, straight chain with acetal linkage (OCF2CF2)p(OCF2)q;B, straight chain without acetal linkage (CF2CF2CF2O)n; C, branched chain (CFCF3CF2O)m, were evaluated at 0.025 mis under 1 to 300 N at 10−5Pa in a four-ball configuration using 440C and Si3N4balls, Φ:6.35 mm, as test specimens. A quadrupole mass spectrometer having a mass range of 1 to 200 amu was employed to analyze gaseous products released from the sliding surfaces.

ISSN:1040-2004    

DOI:10.1080/10402009408983284

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A commercial computer program for data acquisition and analysis has been used to facilitate the evaluation of the frequency content of friction force data obtained from a sliding wear test. The program uses a fast Fourier transform (FFT) algorithm to calculate the frequency spectrum of the friction force. The validity of the FFT program has been demonstrated by applying it to a recently published example that used a detailed mathematical treatment to remove an oscillatory component from friction data. When applied to friction force data from a pin-on-disk sliding wear test of NBD 200 silicon nitride sliding on NBD 100 silicon nitride, filtering of the dominant frequencies revealed by the FFT method reduces both the general dispersion of the friction values and almost completely eliminates localized signal perturbations. Successive filtering steps permit the association of particular frequencies with observed signal disturbances. Although the mean friction value in this example is not greatly altered by the frequency filtering, knowledge of the existing vibration frequency components in the tribosystem is important for a complete interpretation of wear mechanisms and for characterization of the machine/specimen interaction.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983285

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor