Synthesis, Characterization, and Tribological Studies of Calcium–Copper–Titanate Nanoparticles as a Biolubricant Additive

Abstract

In the present study, tribological properties of castor oil have been investigated with and/or without use of additives by using four-ball tester. In the base castor oil, calcium–copper–titanate nanoparticles (CCTO) and zinc dialkyldithiophosphate (ZDDP) were added in different concentrations (i.e., 0.1, 0.25, 0.5, and 1.0 w/v%) to study their individual effect on tribological performance. Tribological test results have shown that there is an improvement in the antiwear, extreme-pressure (EP) properties at 0.25 and 1.0 w/v% for both the additives, respectively. However, in the coefficient of friction (COF) test (incipient seizure load), an optimum concentration of 0.5 w/v% was observed for ZDDP additive, whereas CCTO nanoparticles have shown similar level of performance at all concentrations. The worn-out surfaces were analyzed by using different analytical tools.

Tribological evaluation of calcium‐copper‐titanate/cerium oxide‐based nanolubricants in sliding contact

“…Also, some nanoparticles get deposited in the valleys to smoothen the interface. Another phenomenon that may associate with the nanolubricants (Figure C) is a nanobearing effect or simply rolling mechanism of the nanoparticles; the contact pressure experienced on each ball is huge (typically 3.402 GPa) . Therefore, there is a chance of embedment of the nanoparticles into the comparatively softer ball surface.…”

“…Also, it helps in asperity gouging. The presence of nanopits ascribes the partial indentation of the nanoparticles on the mating surfaces during sliding under higher contact stresses . It is also noticeable that, in spite of the presence of nanoparticles in the oil, complete separation of the mating surfaces is not possible because of higher applied load; therefore, asperity‐asperity interaction and collision may take place at few spots.…”

“…This may be due to the presence of a threshold number of the particles available between the friction surfaces, which separates the mating surfaces and particles rolling. But, with an increase in time, these nanoparticles experienced fatigue under higher contact stresses (typically 3.402 GPa) and initiation of fracture takes place. This makes the sphere (almost) nanoparticles become irregular in shape, which slides over the friction surface and gouges out, resulting in increased friction.…”

“…The compositions of the balls were 0.95% C, 0.15% Si, 0.24% Mn, 0.02% P, 0.018% S, 1.3% Cr, and remaining Fe. The synthesized CCTO nanoparticles, in our previous study, were used as one of the nanoadditives . CeO 2 nanoparticles were procured from AVANSA technologies and services, Kanpur, India.…”

“…In the past, CuO, CaCO 3 , and TiO 2 nanoparticles were tested in different oils individually to evaluate their tribological performance . Therefore, in the present work, as‐synthesized calcium‐copper‐titanate (CCTO) nanoparticles prepared by the sol‐gel method were used to study the combined effect of aforementioned three nanoparticles in the paraffin oil (PO). The concentration of the nanoparticles in the base oil was varied as 0.1, 0.25, 0.5, and 1.0% w / v .…”