Effect of N₂ Flow Rate on the Microstructure， Mechanical Properties，and Tribological Performance of AlCrTiCN Coatings

N2 flow rate is an important preparation parameter in the deposition process of nitride coatings.To investigate its effect on the microstructure， mechanical properties， and wear resistance of AlCrTiCN coatings， a combination of pulsed direct current magnetron sputtering and radio frequency magnetron sputtering was employed.Five different AlCrTiCN coatings were prepared by controlling various N2 flow rates (0，5，10， 15， 20 mL/min).The results showed that when the N2 flow rate was 0 mL/min and 5 mL/min， the AlCrTiCN coatings mainly consisted of pure metals and their carbide phases.As the N2 flow rate increased， the degree of amorphization in the coatings increased， the coating thickness gradually decreased， and the surface quality significantly improved.The hardness and elastic modulus of the coatings initially increased and then decreased， with the maximum values (23.1 GPa and 622.3 GPa) achieved at an N2 flow rate of 10 mL/min.The coating-substrate adhesion strength increased with the N2 flow rate and reached its maximum value of 30.8 N at an N2 flow rate of 20 mL/min.Due to the improvement in mechanical properties and the combined effect of the nanocrystalline-amorphous structure， the coating prepared at an N2 flow rate of 10 mL/min exhibited the lowest wear rate of 5.7×10-6 mm3/(N·m)， showing optimal wear resistance.The main wear mechanisms of the coatings prepared at different N2 flow rates were different.Adhesive wear was dominant in coatings prepared at N2 flow rates of 0， 15， 20 mL/min， while abrasive wear was dominant at 5 mL/min and 10 mL/min.In conclusion， N2 flow rate significantly affected the microstructure and overall performance of AlCrTiCN coatings.The coatings prepared at 10 mL/min exhibited the best mechanical and wear resistance properties.This study provided a reference for the design and optimization of high-performance multi-component coatings.