Development of metal processing liquids containing ecological corrosion inhibitor

Corrosion is a process which negatively affects the chemical and physico-mechanical properties of metallic materials by oxidizing them as a result of chemical and electrochemical reactions with their environment. This process, also called "metal cancer", is one of the most fundamental problems encountered in all industries where metals are used. During machining, metalworking fluids are used to lubricate, cool and remove chips by forming a film between the tool tip and the metal being machined. The film layer provides a smooth machined metal surface while preventing tool tip wear. Rapid removal of the particles released by machining is an important factor that increases production efficiency. The use of fluids is needed during chip removal in order to prolong the life of the cutting tools and to protect the treated metal against corrosion. In order to reduce the corrosion rate, organic and mainly inorganic compounds called inhibitors are added to the metalworking fluids. Most of these chemical additives are known to be harmful to human health and the environment. L-arginine is a kind of amino acid frequently used by athletes as a food supplement. In this study, electrochemical impedance spectroscopy (EIS), chip corrosion testing, SEM and EDS methods were applied to demonstrate that L-arginine can be used successfully as an ecological corrosion inhibitor in metalworking fluids to fight against corrosion instead of the currently preferred tolitriazole.