X-ray study on repeated bending loading process of TiN and TiC coated materials
Matsue Tatsuya; Hanabusa Takao; Ikeuchi Yasukazu
Abstract:Residual stress is generated in coating films due to difference in thermal expansion between film and substrate. Since the residual stress influences the mechanical properties of coated material, it is important to measure the residual stress in the film and the substrate. In this study, 5 mm thick TiN and TiC films deposited on the spring steel substrates using multi-arc (M-A) and dynamic mixing (D-M) methods. In the TiN films deposited by the M-A method, the compressive residual stress of -5.5 - -4.0 GPa was measured, and its absolute value decreased with increasing depositing temperature. Similarity the compressive residual stresses of -2.0 GPa and -7.2 GPa were measured in the TiN film deposited by the D-M method and TiC film deposited by the M-A method, respectively. In the substrate near the film/substrate interface, small compressive residual stress of -25 - -10 MPa was measured under the as-deposited condition. The residual stress change during the repeated bending stress was measured in the substrate and the film. In the substrate of TiN coated specimen, the residual stress increased in the early stage of repeated bending stress and saturated at the stress value of -110 - -40 MPa. The saturated stress increases with increasing applied stress. On the other hand, the residual stress did not change in the substrate of TiC coated specimen. In addition, the residual stress in the films did not change during the repeated bending stress in all the coated specimens. Key Words:TiN, TiC, residual stress, X-ray diffraction, multi-arc PVD method, dynamic mixing method, repeated bending process