Tribology of steel/steel interaction in oil-in-water emulsion; a rationale for lubricity

Role of surfactant head group and chain length in aqueous lubrication: Steel−steel contact

“…This can be attributed to the argument that when surfactant monomer is able to anchor the steel surface then it can reduce the friction. As literature says [3][4][5][6]16,19,31,39,40 when surfactant concentration in water is below CMC then there will be only surfactant monomers, with no micelle present in the solution, which may lead to incomplete coverage of steel surface with surfactant molecules creating a kind of starvation of surfactant molecules to surface and hence for friction reducing agents. On the other hand when surfactant concentration is above CMC in that case micelles or other surfactant aggregates may form by packing their hydrophobic tails inside the aggregates and reducing the free monomers concentration in the solution.…”

“…The concept of green tribology can be promoted by reducing or eliminating the use of oil from metalworking fluids. Kumar et al 26 proposed that nano-emulsions of oil-in water can help in reducing the amount of oil from 5% to 0.5À1% and lubrication behaviour controlled by small droplet size distribution.…”

Contribution of different physical forces to the disjoining pressure of a thin water film being pressed by an oil droplet

“…The surface charge density depends on proton balance between the oxide surface and the solvent, the equilibrium is controlled by acid-base properties of both the hydroxyl surface groups and the solvent molecules. The surface potential of the stainless steel substrate was measured by pH-titration method [36] to be À235 mV. At pH 3, the steel surface is positively charged and this gives rise to an attractive electrostatic force (see inset of Fig.…”

Sensory perception and lubrication properties of milk: Influence of fat content

“…Usually these measurements are done in and relevant to the boundary regime. Kumar, Daniel, and Biswas (2010) recently argued that it is entrapment of small and marginally stable oil droplets that provides the lubrication. However, in practice, rather crude emulsions are used for cutting metal.…”