CHARACTERIZATION OF THE ION-PLATED TIN ON AISI-304 STAINLESS-STEEL BYENERGY-FILTERING TRANSMISSION ELECTRON-MICROSCOPY

The microstructure and chemistry of TiN coatings on AISI 304 stainless steel:was characterized by a Zeiss EM 902A energy filtering transmiss ion electron microscope (TEM) equipped with an electron energy loss sp ectroscopy (EELS) detector. Deposition of the TiN thin films was carri ed out by a hollow cathode discharge ion plating coater. The microstru cture across the coating thickness direction and near the TiN/steel in terfaces was investigated by plan-view TEM. It was found that the micr ostructure of the TiN coatings is thickness dependent. The grain size of TIN ranges from 88 nm at the coating surface down to 9 nm near the TiN/steel interface. In addition, the TIN surface layer shows slightly textured microstructure, but the subsurface and internal TIN layers h ave mainly equiaxial and randomly oriented microstructure. Chemical an alysis of the coating and the interfacial region was done by EELS. It was obtained that the relative oxygen content increases linearly from the TiN surface to the TiN/steel interface, whereas the relative nitro gen content first decreases slowly and then drops rapidly near the int erface. The presence of a Ti2N phase and the deficiency of nitrogen ne ar the TiN/steel interface suggest that the early deposited TiN may be nonstoichiometry. (C) 1997 American Vacuum Society.