Investigation into the Structure of TiN Single-Layer and TiN/ZrN Multilayer Coatings

The structure of ion plasma coatings (single-layer TiN and multilayer TiN/ZrN) deposited on an EI961 alloy substrate was studied, and the values of residual stresses were determined separately for each phase of the coating. A scanning electron microscopy investigation showed that the TiN/ZrN coating has a periodical layered structure. The thickness of coatings (similar to 17 mu m) and separate layers (similar to 75 nm) was measured. The results of dark-field studies by transmission electron microscopy showed that TiN and ZrN layers are polycrystalline, and the dimensions of grains are comparable with the dimensions of layers. An X-ray structural analysis was used to determine the phase composition of coatings, X-ray lines were chosen to determine the residual stresses, and the homogeneity of the chemical composition along the coating depth was determined. An analysis of the residual stresses showed that their value for the multilayer coating was 40% less than that for the single-layer one. Stresses in the coating are compressive. Samples with a coating are in the volume-stressed state; consequently, stresses in the substrates have the opposite sign of the stresses in coatings. In the multilayer coating, the residual stress value in the TiN phase is much less than that in the ZrN phase.