Mechanical and Electrochemical Properties of Titanium Aluminum Nitride Coatings with Different Nitrogen Flow Rates on CrMnSi Steel by Filter Cathode Vacuum Arc Technology

In order to address the weaknesses of poor corrosion resistance of hydraulic cylinder piston rods, we have developed a surface protection strategy for titanium aluminum nitride coatings by filter cathode vacuum arc (FCVA) technology. The optimization and regulatory mechanism of N2 flow rate on the microstructure, mechanical, and electrochemical oxidation behaviors have been emphasized. The results indicated that all coatings revealed a nanocrystalline amorphous composite structure dominated by an fcc TiAlN phase. However, the solid solution content, growth orientation, and grain size could be controlled by the nitrogen flow rate, thereby achieving optimized hardness, adhesion strength, corrosion, and oxidation resistance. Specifically, with the increase in the N2 flow rate, the solid solution content continued to rise, while the crystal orientation transformed from the (111) to the (200) plane, and the grain size initially increased and then decreased. As a result, mechanical properties, including hardness, toughness, resistance to plastic deformation, and adhesion strength, displayed a trend of initially increasing and then decreasing. The corrosion failure of coatings was linked to surface defects controlled by the N2 flow rate, rather than the composition and phase structure. The coating displayed superior corrosion resistance at low N2 flow rates due to fewer macroscopic particles and pore defects. This study provides valuable insights into the corrosion behavior of an aluminum titanium nitrogen coating, providing crucial guidance for coating design in harsh environments.