Preparation And Properties Of （AlCrTi）-Si-N Medium Entropy Coatings Deposited By Plasma-enhanced Magnetron Sputtering

Due to high hardness,low coefficient of friction and strong adhesion,Ti N coatings were widely used as surface protection materials for various mechanical workpieces,which can effectively improve work efficiency and extend service life.With the development of science and technology,traditional coatings were difficult to meet the requirements of modern processing.The preparation of multi-nanocomposite medium entropy coatings to further improve their hardness and toughness,enhance wear and corrosion resistance,will greatly expand the application scope of Ti N-based coatings.In this paper,the（AlCrTi）-Si-N medium entropy nanocomposite coatings were prepared by plasma-enhanced magnetron sputtering（PEMS）,focusing on the influence of substrate bias voltage and nitrogen flow rate parameters on the microstructure,mechanical properties and friction properties of（AlCrTi）-Si-N coatings.（AlCrTi）-Si-N coatings under different bias voltage were prepared by PEMS technology.The study found that all coatings were Na Cl-type FCC solid solution structures,which were optimally grown along the（111）crystal plane.With the increase of bias voltage,the N content increased from 38.96%to 52.88%.At a bias of-75 V,the coating had the highest microhardness（25.28 GPa）and optimal adhesion strength（33.67 N）.After exceeding-75 V,the hardness and adhesion strength of the coating decrease to a certain extent.The friction coefficient of the（AlCrTi）-Si-N coating under different substrate biases is between 0.5 and 0.6,the coatings had the lowest coefficient of friction（0.507）and the lowest wear rate(1.0×10^-6g/N·m)when the substrate bias voltage was-75 V.Under different bias voltage,the failure mechanism of（AlCrTi）-Si-N coatings were the combination of abrasive wear and oxidative wear.（AlCrTi）-Si-N coatings were prepared using PEMS technology at different nitrogen flow rates.The study found that all coating surfaces were irregular particles,and the surface is uneven.（AlCrTi）-Si-N coating between the layers of the good combination,no obvious defects.With the increase of nitrogen flow,the porosity and roughness decrease first and then increase,and the deposition rate continues to decrease.At a nitrogen flow rate of 40 sccm,the coating had the densest surface structure,the lowest porosity（2.61%）,and the lowest average roughness（9.06 nm）.With the nitrogen flow rate increases,the microhardness,adhesion strength and mass wear rate of the coatings all show a change of decrease after the first increase.Under different nitrogen flow rates,the failure mechanism of（AlCrTi）-Si-N coatings were the combination of abrasive wear and oxidative wear.