| abstract |
A layer of zirconia, or other ceramic oxide material, is deposited on a number of conductive substrates 9 using a d.c. biased, thermionically enhanced, plasma assisted physical vapour deposition technique. The layer may be deposited oxygen deficient, and subsequently oxidised by heating in an oxygen environment. A preferred material deposited is a zirconia based material. In the specific embodiment, as illustrated in the Figure, there is provided a thermionic emitter, 11, which may be a tungsten or titanium filament, the support platform 8 for the substrate being connected to a d.c. power supply 10 arranged to maintain the platform 8 at a negative potential. In use a glow discharge may be initiated by applying a potential of several kV to the support platform so as to initiate a d.c. diode mode glow discharge. Alternatively the filament heater 11 itself may be activated so as to produce a filament omission current with a negative potential applied to the filament and a negative bias being applied to the support platform 8 and initiate a d.c. triode mode glow discharge. A positively biased electrode may be introduced into the plasma generated to raise the plasma potential and cause the surfaces of the workpieces to be bombarded with ions and neutral species as well. <IMAGE> |