posted on 2024-03-01, 13:06authored byArun Kumar, Vivek Kumar, Yogesh M. Joshi, Manjesh Kumar Singh
A thixotropic colloidal gel constituting
an aqueous dispersion
of synthetic clay Laponite with varying concentrations of salt has
been studied for its rheological and tribological performance as a
lubricant. We observed that the incorporation of NaCl induces notable
enhancements in the colloidal gel’s relaxation time, elastic
modulus, and yield stress. Although an increase in NaCl concentration
decreases the material’s relaxation time dependence on waiting
time (tw), overall, the strength of its
thixotropic character has been observed to increase with an increase
in salt concentration. The analysis of friction and wear indicated
that the utilization of a thixotropic colloidal gel of Laponite with
a higher concentration of NaCl resulted in progressively greater reductions
in both the coefficient of friction and specific wear rates under
various load-speed conditions. Severe abrasive wear on disc surface
under dry test, gradually mitigated upon the introduction of these
lubricants. Two simultaneous lubricating mechanisms, first, the smooth
sliding of the friction pair, facilitated by the alignment of Laponite
particles in the direction of shear forces, and second, the stable
structure of Laponite, coupled with the addition of NaCl, enabling
continuous replenishment of the wear track with lubricant, are attributed
to lubrication effectiveness.