Preparation of Ti-TiC functionally gradient material by hollow cathode discharge ion plating

摘要

Recently, active research on a new type of compo-site, which is called functionally gradient material (FGM) [1], has been carried out in order to give multiple functions to composites. FGM can be prepared using a variety of methods, such as powder metallurgy [2] and chemical or physical vapour deposition (CVD or PVD) [3,4]. Generally, it is easier to control the composition with the PVD method than with the other methods. However, a significant disadvantage is the low deposition rate. Within the PVD process, a hollow cathode discharge type of ion plating (HCD-ion plating) can produce a high deposition rate because of the high ionization of the evaporated atom and the high current density [5]. Shiota et ol. have prepared Ti-TiC FGM by HCD-ion plating, and have investigated the thermal stability of the FGM [6,7]. In this letter, preparation of Ti-TiC composites with various compositions and FGM in the system by HCD-ion plating is described. Fig. 1 shows a schematic diagram of the apparatus. Metal titanium was evaporated by a plasma beam emitted from an HCD gun, then the vapour reacted with CH4 gas introduced into the chamber on carbon substrates kept at 500 °C, to which an RF bias of 13.56 MHz was applied. The composition of the deposits was controlled by changing the flow rate of CH4. Phases in the deposits were determined by X-ray diffraction (XRD).