Industrial Surface C Leaning Using Halogen Free Cleaning Agents: Surfactant Solutions and Hydrocarbon Solvents

Abstract

Minimising the health and environmental risks resulting from surface cleaning involves the design of suitable hardware but also the choice of a cleaning agent. As an alternative to chlorinated hydrocarbons, chlorine free hydrocarbons or surfactant cleaners in aqueous solution can be used. Whereas hydrocarbons work as solvents and remove mainly soluble oil or fat contamination, surfactant cleaners dissolve water soluble contamination and displace oils, fats, and insoluble particles, swarf, chippings, and cuttings. While it is advantageous to work with water as a solvent, many alkaline surfactant cleaners contain inorganic salts which leave non-volatile residues at metal surfaces ifthe parts are not rinsed sufficiently with desalinated water. Laboratory scale cleaning experiments with both types of cleaning agent have been carried out. Results were obtained by analytical means and modern surface analysis; in addition, gas nitriding, a surface modification process which is known to be sensitive to surface composition, was used to assess cleaning potential. For the total process of machining, cleaning, and nitriding, it is shown that it is neither possible nor sensible to define a standard of surface purity without considering the special demands of the surface modification process following.