OBRABOTKAMETALLOV Vol. 26 No. 2 2024 technology Fig. 6. Experimental setup for electrochemical hole machining: 1 – electrolyte supply system; 2 – electrochemical cell; 3 – anode (blank); 4 – cathode-tool; 5 – three-coordinate machine; 6 – technological power source The gap between the anode and the cathode during the technological experiment was 0.1 mm [29, 31–34]. Following the experiment, the sample was placed in an ultrasonic sludge cleaning bath and subsequently weighed on high-precision laboratory scales (the division value is 0.1 mg). The depths of the holes were measured by digital micrometer GRIFF (0–12.7 mm; with the division value of 0.001 mm). Photographs of the specimen were taken using a Nikon MM-400 microscope with 30× magnification. Results and discussion The results of polarization studies have enabled the features of anodic dissolution of tool steel U10A to be established (Fig. 7). The anodic behavior of the steel under study in a 10 % solution of a neutral salt of NaCl in water exhibits a characteristic curve. This curve indicates that the active dissolution of steel occurs within a specific potential range between φ = 0.3...8.0 V with slight inhibition in the potential range φ = 2.1...2.6 V and φ = 3.9...4.3 V. This is probably due to phenomena that occur during the electrolysis of steel in an aqueous salt solution, such as the oxidation of the material under study and the decomposition of water [28–30, 31–33]. The general nature of the electrochemical dissolution of U10A steel in 10 % NaCl in water indicates the absence of passivation sites. This is due to the fact that during the electrochemical dissolution of materials in sodium chloride, passivation phenomena are removed by increasing the voltage without introducing additional activating processes [28–34]. Fig. 7. Anodic polarization curve of U10A tool steel in 10 % aqueous NaCl solution
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