Effect of pulsed electric field on the nanocrystalline growth of magnetron-sputtered TiAlN hard coatings

Coatings prepared by magnetron sputtering have smooth surfaces; however, their columnar structure is conducive to crack propagation, which results in a short service life. Furthermore, the heating and cooling rates of the traditional method in vacuum chambers are slow and reduce preparation efficiency. In this work, the pulsed electric field (PEF) is used to suppress columnar growth and replace the traditional heating method. The results show that the electric field force and the Joule heat of the PEF promote the short-range atomic diffusion and the nucleation rate of nanocrystals. The critical load Lc1 of the nanocrystalline PEF coating can reach 95 N; the cutting distance is improved by 100% in comparison to the uncoated tool. Additionally, the PEF reduces the heating and cooling time significantly. The effect of the PEF is better than that of the traditional heating method. The preparation efficiency improves by about 41.2%. These results indicate that the PEF can not only guarantee coating properties but also improve the preparation efficiency.