Prediction of Pressure-Viscosity Coefficient of Mixtures

Abstract

The pressure-viscosity coefficient α is one of the most important property for EHL condition, however its measurement has difficulty. Therefore authors attempt to predict α for blend oils by using the relationship between pressure-viscosity coefficient and logarithm of kinematic viscosity at atmospheric pressure, which is used for single oil as ever. The pressure-viscosity coefficient of mixtures enables to predict with base oils properties and viscosity of mixture at atmospheric pressure. Test fluids are SN-HV, PBSN, DOS, BBPH and mixtures of these oils. High-pressure viscosity measurement was done at pressure up to 0.4 GPa and temperature range at 20ºC to 100ºC. The authors proposed the prediction method of α for mixtures.

Correlation of structure and properties of groups I to III base oils

“…The film thickness produced by test oil ( H t ) and the reference oil ( H r ) at the same fixed value of (u * η) were taken from the graph and used for the estimation of pressure–viscosity coefficients of test base oils. The pressure–viscosity coefficients at different temperatures were estimated using the film thickness of a reference oil of di(2‐ethyl hexyl) sebacate (DOS) . The pressure–viscosity values of DOS at different temperatures are calculated using the relationship between kinematic viscosity and pressure–viscosity coefficient provided by Hayashi et al (α of DOS = 11.865 at 30°C, 9.599 at 60°C and 7.554 at 100°C) and used for the estimation of pressure–viscosity coefficients of base oils under study using the following equation: where H and α are the film thickness and pressure–viscosity coefficient with the subscripts ‘t’ and ‘r’ indicating the test sample and reference, respectively.…”

“…The 1 H/ 13 C-NMR spectral recordings were carried out on a 300 MHz FT-NMR in CDCl 3 solution, and tetramethyl silane was used as an internal reference. The quantitative 13 C-NMR spectra were recorded in a 30% solution prepared in CDCl 3 containing 0.1 M chromium acetyl acetonate as the relaxation agent ( Figure 1). 1,2 A total of 10 000 scans with a relaxation delay time of 5.0 s were given for achieving the best S/N ratio for obtaining the quantitative 13 C-NMR spectra.…”

“…The pressure-viscosity coefficients at different temperatures were estimated using the film thickness of a reference oil of di(2-ethyl hexyl) sebacate (DOS). 13 The pressure-viscosity values of DOS at different temperatures are calculated using the relationship between kinematic viscosity and pressure-viscosity coefficient provided by Hayashi et al 13 (a of DOS = 11.865 at 30 C, 9.599 at 60 C and 7.554 at 100 C) and used for the estimation of pressure-viscosity coefficients of base oils under study using the following equation:…”

“…The log(H c /D) versus temperature (1000/T) plot is shown in Figure 6. The higher value of proportionately constant K is indicative of large variation in EHD film at high temperature for group I (K, 276-290) and group II (K, 104-133) compared with group III base oils (K, [6][7][8][9][10][11][12][13]. It is also evident from the value of D and H c that the film thickness of groups I to III base oils is dependent on hydrocarbon composition and mobility of the molecule at a given temperature.…”

Molecular Dynamics of Synthetic-Based Lubricant System by Spectroscopic Techniques—Part 1

“…The pressure-viscosity coefficients at different temperatures were estimated using the film thickness of a reference oil of di-(2-ethyl hexyl) sebacate (DOS). The pressure-viscosity values of DOS at different temperatures were calculated using the relationship between kinematic viscosity and pressure-viscosity coefficient provided by Hayashi, et al (29) (α of DOS = 11.016 at 40 • C, 9.599 at 60 • C, 8.469 at 80 • C, and 7.554 at 100 • C) and used for the estimation of pressure-viscosity coefficients of synthetic base oils under study using the following equation:…”