MICROSTRUCTURE, CHEMISTRY AND COATING PROPERTIES OF ION-PLATED TIN ONTYPE-304 STAINLESS-STEEL

Characterization of TiN coatings on type 303 stainless steel was carri ed out using a Zeiss EM 902A energy filtering transmission electron mi croscope equipped with an electron energy loss spectroscopy (EELS) det ector. TiN thin films were produced by a hallow cathode discharge ion plating coater. It was found by plan-view transmission electron micros copy that the microstructure of the TiN coatings is thickness dependen t. 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 la yer shows some degree of texture, but the subsurface and internal TiN layers are mainly equiaxial and randomly oriented. Chemical analysis b y EELS shows 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 is non stoichiometric. By the periodic cracking method, the ultimate sheer st ress at the TiN/steel interface and the residual stress in the TiN thi n film were estimated to be 2.2 GPa and 12.8 GPa, respectively. (C) 19 97 Elsevier Science S.A.