The viscosity-pressure-temperature dependence of mineral oils (in German)

401

LITERATUREANDCURRENTEVENTS

Authors’ Study of the Thermal

Abstracts

Behaviour of Diesel Engine Oils (in French)

M. MACNABANDM. A. DE GOLDLIN*, SociCtC ANTAR (Paris). The bench test makes it possible to study the behaviour of a lubricant in operation. But, since it is long and costly, it must itself be preceded by simpler tests which enable direct researches to be carried out. It is for this purpose that ANTARlaboratories developed a coking bench where the oil undergoes a similar aging to that observed in a diesel engine. When sprayed onto a heated metal surface, it drips together with condensates into a cold beaker and the process is then repeated, following the same cycle as the lubricant does in the engine, passing from the hot cylinder walls to the cold sump. The adopted device is flexible enough to enable operation under various temperatures, and accurate enough to provide reproducible results. The coke and varnishes produced on the hot surface, both by the liquid oil and by its vapours, are examined, as are the oil characteristics at the end of the test. Thus, curves are obtained of, for example, coke weight versus time or acid index versus time at various temperatures. The optimum composition for a mineral oil could first be determined, and then the improvement of its thermal strength resulting from the addition of various dopes. The comparison of the curves of various lubricants obtained on the coking bench, and of the PETTER engine data, showed a clear relationship between both sets of results. The value of the coking bench as a research instrument was thus demonstrated. Wear, 3 (1960) 401

The Viscosity-Pressure-Temperature

Dependence of Mineral Oils (in German)

E. Kuss (Institut fur Erdolforschung, Hannover, Germany) - Materia@rGfung, (1960) rSg-rg7;

z (6)

(9 fig., 4 tables, 35 ref.).

Owing to the complexity of multicomponent mineral-oil systems of unknown molecular structure, it is much more difficult to predict the technically important dependence of viscosity upon pressure for lubricating oils than it is for chemically well-defined substances. Difficulties are enhanced when oil additives are present. A considerable number of lubricating oils, some of widely varying composition, were investigated up to 2000 atmospheres, with the following results: (a) Characterization of the oil composition, for instance with the aid of Waterman’s method, is not sufficient for determining viscosity-pressure behaviour. At least * Lecture given to the “SociBt.5 des In&nieurs de 1’Automobile”. For information and reprints write to: ANTAR, 4 Rue LBon Jost, Paris 17; c/o Direction Technique & Etudes, Section Constructeurs et Documentation. WW’, 3 (1960) 401-402

$12

LITERATUREAKDCURRENTEVENTS

the degree structural

of branching

should

be additionally

accounted

for by means

of a

coefficient.

(b) The relation between the pressure coefficient tion was shown not to be sufficiently

of viscosity

accurate

and the energy of activa-

for predicting

pressure dependence

on viscosity. (c) However,

a prediction

an accuracy

of the viscosity-pressure

of about 5-7%,

values of the Waterman The presence additional

of additives,

correction

viscosity-pressure matically.

can be derived with

is used in connection

with certain

analysis. such as lead-naphthenate,

of the value of density. coefficient

The new method of predicting

must be accounted

In this way great

with temperature

will be taken

viscosity-pressure

was checked by means of our own experimental ASME

coefficient

if the aniline-point

for by an

variations

into

of the

account

behaviour

auto-

of mineral oils

data as well as of the results of the

project.

(See also: E. KUSS:Z.

anger. Phys., IO (1958) 566-575.) Wear,

3 (1960)

401-402

Wear Research and Rheology (in German)

G. SALOMON

(Centraal

fung,I (x1/12)(1959)

Laboratorium 385-390;

should

between

bulk properties

Some of the concepts used in technological

The theory

of friction

be considered

between

primary

Although yet possible

is then used as a starting separately.

processes

maximum to predict

in friction

rubbers

and fibres is briefly

outlined.

that the wear resistance

and temperature,

is determined

point. Elastic

of

and plastic

approaches

processes

give a correlation

and in wear. of rubbing

properties

and wear resistance

work on wear are first explained.

statistical

all the consequences

and of rheological

technology

Recent

temperatures

thermal

Materialfwii-

Delft, The Netherlands)

(4 fig.; 51 ref.).

A study is made of the correlation materials.

T.N.O.,

surfaces

can be calculated,

of frictional

on the ultimate

of

of abrasives,

from recent

under extreme

by their thermal

The influence

wear resistance

It can be concluded

of materials,

heating.

it is not

advances

conditions

in

of pressure

and also by their rheological

prop-

erties. Wear,

Stick-Slip

H. CATLING

Friction as a Cause of Torsional Vibration

(Institution

of MechanicalEngrs.,

3 (1960)

402

in Textile Drafting Rollers

London). Advance copy No. 26/59 (r96o)

7 pp. ; (g fig., I table, 7 ref .) Torsional

vibration

of long rollers stimulated

by stick-slip

frictional Weur,

behaviour 3 (1960)

con-

402-403