F. Legaydesesquelles et al., SEDIMENTATION OF METALLIC PARTICLES IN OILS AND EMULSIONS, Colloids and surfaces. A, Physicochemical and engineering aspects, 75, 1993, pp. 75-83
Sedimentation tests have been used to analyse the interaction forces b
etween micrometric carbonyl iron and steel particles suspended in mode
l liquids and emulsions which are representative of rolling lubricants
of the steel industry. In non-emulsified liquids, the stability and t
he final packing of the suspension depend on the polarity of the liqui
d, the nature of the various additives and their mutual solubilities.
In cyclohexane solutions of fatty acids, the aggregation of the partic
les and the suspension stability can be changed in a continuous way wi
th the solute concentration. The final solid volume fraction also vari
es and follows a saturation-like behaviour with two plateaux, the valu
es of which depend on the type of particle. Carbonyl iron suspensions
reach the closest packed value (0.62) for concentrated solutions and t
he parking limit (0.38) at intermediate concentrations. Steel suspensi
ons exhibit very low packing densities (from 0.07 to about 0.20). Sedi
mentation of steel suspensions in industrial emulsions depends strongl
y on the oil concentration and the results can be interpreted by compa
rison with model suspensions.