AFM, Nano − indentation and TEM characterization study of HFCVD diamond on tantalum and diamond seeded cemented carbide inserts

Abstract

This research describes an enhanced characterization technique for studying diamond production by hot filament chemical vapor deposition (HFCVD) on cemented carbide (WC − Co) SPUN inserts. The characteristics of diamond (Dia.) and tantalum (Ta) seeded powders used as seeding materials were determined using a variety of microscopic characterizations. Topographic and cross-sectional pictures obtained using field emission scanning electron microscopy (FESEM), respectively, demonstrate that the Ta-seeded substrate had a higher nucleation density, whereas the Dia.-seeded substrate had thicker coatings. Findings from atomic force microscopy (AFM) show that Ta-seeded substrates' mechanical strength is expectedly higher due to the smaller grains and higher apparent density. According to the X-ray diffraction (XRD) results, the Dia. − seeded substrate displayed a lower dislocation density, strain, and Burgers' vector magnitude. The highly crystalline structure of the Ta-seeded sample appeared in the Transmission electron microscopy (TEM) selected area electron diffraction (SAED) images. However, the multi-gradient sample structure of the Dia.-seeded Sample obtained increased its ductility property. The nanoindentation results demonstrated that the Ta-seeded substrate had a higher hardness while the Dia.-seeded substrate had a higher Stiffness and Youngs' modulus value. The findings are crucial for present-day CVD applications since Ta powders offer an alternative option to diamond powders.