Evaluation of Additives as Corrosion Inhibitors/Antioxidants for High Quality Nano Emulsifiable Oils of Metalworking Fluids

Abstract

Surfactants used for formulation metal working fluids. In the present paper, the inhibitive effect of synthesized anionic surfactant P-decyloxy p-sodium sulphonateazobenzene with chemical structure H21C10O-Ph-N=N-Ph-SO3Na and 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine on the corrosion of carbon steel in sulphuric acid solution is measured by the weight loss method. The relationships between the concentrations of these inhibitors and their surface properties, thermodynamic properties, surface coverage and inhibiting efficiency, have been investigated. The results indicate that P-decyloxy p-sodium sulphonate azobenzene is superior to 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine at high acid concentration. These inhibitors blend with coupling agent to produce water miscible cutting fluid. Values of surface tension of these additives were measured in water phase and consequently CMC was determined for all inhibitors. The efficiency of these inhibitors depends on their chemical structure and the presence of hydrophilic group to association of the surfactant with metal surface, hence very good wetting properties. The anti-corrosion characteristic of surfactants increases with increasing polar linkages in the aromatic moieties forming chelated and coordinated layer. This is due to the increase in number of sites to chemisorption on the metal surface. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the surfactants and their efficiency. More confirmation for suggested mechanism was investigated by measuring the area occupied per molecule of the surfactant at aqueous phase. The results indicate that the amphoteric surfactant more efficient than anionic surfactant. The antioxidants activities of different dosages of inhibitors were evaluated and suggested mechanism according to their thermodynamics parameters. The oxidation of the oil has been carried for different time intervals.