Effect of Si Doping and Layer Embedding on the Microstructure and Properties of AlTiN-Based Coatings
摘要
AlTiN coatings are widely used to protect metal substrates from corrosion and wear due to their high hardness and excellent wear and corrosion resistance. To improve the performance of AlTiN coatings, element Si-doped AlSiTiN coatings and thin layer Si embedded AlTiN/Si multilayer coatings were prepared on 304 stainless steel substrates by magnetron sputtering. The effects of Si doping and Si layer embedding on the morphology, roughness, structure, composition, hardness, friction coefficient and corrosion resistance of AlTiN coatings were investigated and compared. The results show that the AlTiN monolayer coating presents a nanocrystalline (AlN) structure, the AlSiTiN monolayer coating has a nanocrystalline (AlN)–amorphous composite structure, and the Si embedding layer is amorphous. The Si doping and Si layer embedding effectively suppressed the surface pinhole defects and columnar structure of the AlTiN coatings, and the grain size was reduced from 21 to 14 and 10 nm, and the surface roughness Ra values decreased from 8.37 to 3.43 and 2.44 nm, respectively. The hardness of the coatings was increased from 7.6 to 12.6 and 17.1 GPa, respectively. The coefficients of friction were reduced from 0.91 to 0.75 and 0.64, respectively. The corrosion current densities were reduced from 6.81 × 10−8 to 1.95 × 10−9 and 1.22 × 10−9 A/cm2, respectively. The improvement mechanism of Si doping and Si layer embedding on the properties of AlTiN coatings is revealed in detail.