Thin coatings AlN, AlZrN, and AlCrN were deposited by pulsed magnetron sputtering. The high-speed steel Т1, structural alloy steel 5140, and structural carbon steel 1017 were used as substrates. The magnetron current, nitrogen content in the gas mixture, and bias voltage on the substrate were changed to obtain nanostructured and amorphous layers of coatings with different elemental compositions. The voltammetry and impedance spectroscopy were performed on the coated samples in 3% NaCl solution. The corrosion behavior of the coatings was characterized by the corrosion current density i corr, the polarization resistance R p (at the corrosion potential), the ratios i corr,s /i corr , and R p /R p,s , where subscript s refers to the substrate. It was shown that the coatings under study (except AlN) are electrochemically active, and the corrosion processes occur not only on the substrate in the coating discontinuity but on the coating surface as well. The coatings AlN/T1, AlZrN/5140, AlCrN/T1, and AlCrN/5140 with i corr ~10 −7 A cm −2 are found to be the most corrosionresistant in 3% NaCl. The paper discusses factors affecting the corrosion behavior of the investigated coatings.3% NaCl solution, coatings AlN, AlZrN, and AlCrN, structure and electrochemical behavior
| INTRODUCTIONRecently, much attention has been paid to the development of nanostructured coatings with high physical, mechanical, and tribological properties. Such coatings include ZrMN and CrMN (M = Al and Ti) with a hardness of more than 40 GPa; they are simultaneously characterized by thermal and corrosion resistance. In recent years, coatings ZrAlN, CrAlN ZrTiN, and CrTiN with hardness 30-40 GPa are attracting the most attention due to their unique properties, including high hardness, high-temperature oxidation resistance, minimal wear, and excellent thermal stability. [1][2][3][4][5][6] The TiAlN coating exhibits inferior corrosion resistance compared to the TiN coating. Potentiodynamic polarization measurements have shown that for all single layer CrN, TiN, TiAlN coatings, and multilayer nanolayered TiAlN/CrN coatings, the corrosion potential is shifted to higher values compared to the uncoated substrate. The corrosion current density for coated samples decreases. The protective effect of multilayer TiAlN/CrN coatings is higher than that of single-coat coatings. The Nyquist and Bode plots obtained from the EIS measurements were fitted with appropriate equivalent circuits to calculate coating discontinuity resistance, charge transfer resistance, and capacitance. [7] These studies confirm that