Study of the lubricity of emulsion/microemulsion systems for application in cutting fluids.
Cutting fluid, nonionic/anionic surfactant, A/O microemulsion, O/W emulsion, tribological performance
Development of new cutting fluids constitutes an important field of scientific and technological activity, since most of the fluids are part of the consumption of petroleum source, and this source is limited and not renewable. Recently, emulsion systems have been studied as an alternative to improve tribological applications as fluids that improve lubricity. Thus, this work aimed to formulate, characterize and study the tribological performance for O/A emulsions and A/O microemulsion systems with different anionic surfactants (soap base) and non-ionic nonylphenol polyethoxylates with different degrees of ethoxylation to apply as cutting fluids. Epoxidized vegetable oil was use for the development of emulsion and microemulsion systems. The main physico-chemical properties were determined for the formulations, such as density, acidity, iodo index, oxirane index, small angle X-ray scattering analysis (SAXS), particle size, rheological measurements and contact angle. In order to evaluate the tribological performance of the systems, a High Frequency Reciprocating Rig (HFRR) tribromometer, consisting of a plane type ball wear test. Based on the results presented above, it can be concluded that the physicochemical properties analyzed are suitable for the fluid as lubricants. The lower concentration of anionic surfactant (1%) presented lower coefficients of friction for the studied emulsions. The emulsions developed with 5% surfactant showed higher coefficient of friction and wear rate. The microemulsion systems have cylindrical shapes, in which it contributes to higher viscosity in the systems. When comparing the coefficient of friction in systems formulated with different surfactants NP4EO, NP6EO and NP9.5EO, it was observe that the coefficient of friction tends to increase in the systems (M1-M3) as the degree of ethoxylation increased and as increased the concentration of surfactant.