INFLUENCE OF A WATER-MISCIBLE SURFACTANT-BASED CUTTING FLUID ON THE CORROSION OF R6M5 STEEL IN A NEUTRAL MEDIUM

The aim of the work is to research physico-chemical and anti-corrosion properties of surfactants-based water-miscible cutting fluid Gelltex G-430. This cutting fluid is designed for lubricating and cooling of drop feeder scissors of glass-forming machines. It contains mineral and vegetable oils, emulsifiers and corrosion inhibitors. The cutting fluid slows the corrosion of the high-speed steel P6M5 in a neutral medium with a protective effect up to 88%. The cutting fluid demonstrates anodic mechanism of corrosion inhibition. It slows anodic process (oxidation of the metal) and stimulates cathodic process (reduction of the corrosive medium). Therefore, use of this lubricant in acidic media is undesirable because it can cause hydrogen accumulation in the steel and embrittle it. In a water solution, the lubricant builds different types of micelles, which is explained by two horizontal sections on the surface tension isotherm. Change in form of the micelles can affect the anti-corrosion properties of the lubricant. It is confirmed by gravimetric tests. The optimum dilution for this cutting fluid is 1:800. A lower dilution can worsen its protective effect. The range of recommended dilutons of the lubricant should be within horizontal sections on the surface tension isotherm. The lubricant is able to interact with calcium ions (probably building complexes or forming precipitates) and it limits its use in a hard water - a too high concentration of calcium ions in the water can change the structure and anti-corrosion properties of the lubricant.