Long-term stable Ti/BDD electrode fabricated with HFCVD method using two-stage substrate temperature

Boron-doped diamond-film-coated titanium (TiBDD) has become increasingly attractive because of the combined properties of these two unique materials. The challenge for the composite material is stability, especially when it is used as an electrode. In order to meet this challenge, a two-temperature (2-T)-stage hot-filament chemical vapor deposition (HFCVD) method was employed in this study. The accelerated working lifetime was significantly increased to 804 h for the 2-T electrode, compared with 244 h for the diamond-film electrode fabricated under the one-temperature (1-T)-stage method. With the characterization of micro-Raman, X-ray diffraction, and cross-sectional scanning electron microscopy, a multilayer of Ti/TiC/(diamond + amorphous carbon)/diamond could be found in the 2-T sample and the structure of TiTiCdiamond in the 1-T sample. There was less void space observed in the interlayer of the 2-T sample. The multilayered compact structure played an important role in improving the adhesion of diamond film to the titanium substrate, which in turn increased the electrode working lifetime by over two times.