Development of quantitative evaluation on interfacial strength for PVD coated materials.

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The ceramic coating by various types of physical vapor deposition (PVD) is widely utilized to prolong the life cycle of tool and die materials, to prevent substrate materials from initiation and growth of cracks, or to make significant reduction of wear rate. Many researches to progress the coating procedures have been reported anywhere in journals, but very few studies are present to make reliable evaluation and mechanical characterization of these coated materials. This is because little or no methodologies are available to assess the mechanical properties of coatings and their change with loading and scratching in operation. Even to make accurate determination of elastic constants of these coating materials, neither micro-hardness testing nor bending testing has sufficient reliability for the above materials assessment.Authors have been interested in research and development of acoustic diagnosis for materials evaluation. In this research, quantitative nondestructive evaluation of P … More VD ceramic coatings and surface treated materials is aimed to realize a base for the elastic characterization of surface structure of materials in the range from 50 nm to 100 mum, the residual stress distribution analysis in coatings and the acoustic homogenization approach to relate the macroscopic mechanical properties with the microstructure of materials, The key technology lies in the research and development of quantitative nondestructive evaluation system by the acoustic spectro-microscopy. In the final year of this research, new methodology was proposed and developed for the residual stress distribution analysis for the PVD TiN coatings where the difference of the leaky surface wave velocities between coated and reference materials in the function of d/lambda (d : coating thickness and lambda : wave length) can be identified as the residual stress distribution. Furthermore, new ultrasonic measurement methods were developed to describe the change of rheological properties with increase of temperature and pressure and to trace the deformed profile of powder compacts with pressurizing upto 400 MPa. Less