Analysis of antifreeze properties before and after their operation in engine

The results of diagnostics of antifreeze indicators before and after their operation in an internal combustion engine are presented. The chosen direction of research is relevant, since it allows one to predict not only the change in the properties of antifreeze during its operation, but also to obtain evidence of the course of metal corrosion processes. The purpose of the study - to conduct control tests of antifreezes before and after their operation in an internal combustion engine, that ensures the maintenance of the power unit in good condition. The objects of study were fresh AGA Z-40-G12++ antifreeze (release of 2021; A-21) and coolant AGA Z-40-G12+ (release of 2012; AE-12) after its operation for several years. It is shown that the pH, density, viscosity, electrical conductivity of the coolant samples before and after its operation are different. It was found that the course of the dependences of electrical conductivity σ on temperature t for samples A-21 and AE-12 is the same. The dependence of σ on t is described by a polynomial (quadratic) model. It has been suggested that higher values of the AE-12 hydrogen index may indicate the occurrence of electrochemical corrosion of metals, which, in the process of contact with antifreeze, form short-circuited galvanic pairs. With the help of a complete factorial experiment, it was demonstrated that higher pH values of used antifreeze can be a reflection of the degradation of the properties of monoethylene glycol and the ongoing processes of metal corrosion.