Study on the growth and superhardness of TiN/SiO22 nanomultilayers

Superhard and oxide-composed multilayers are promising coatings for tools working under extreme conditions. In this paper, TiN/SiO22 nanomultilayers with vari ous individual SiO22 and TiN layer thicknesses have been prepared by multi-tar gets magnetron sputtering method. The growth structure and mechanical properties of the films have been studied by x-ray diffraction, energy dispersive x-ray spectrometry, high-resolution transmission electron microscope and nanoindenter. It reveals that although SiO22 and TiN monolithic films form amorp hous and nanocrystalline structures, respectively, the TiN/SiO22 multilayers exhibit coherent epitaxial growth due to the mutual growth-promoting effect. At small Si O22 layer thickness (～1nm) S iO22 layers transform into amorphous structure and block the coherent growth of multilayers, and then the hardness and elastic modulus of the multilayers decre ase gradually with increasing SiO22 layer thickness. On the other han d, the cha nging of TiN layer thickness shows a relatively small effect on the growth struc ture and mechanical properties of the nanomultilayers.