LOW-TEMPERATURE PYROLYTIC CARBON-FILMS - ELECTROCHEMICAL PERFORMANCE AND SURFACE-MORPHOLOGY AS A FUNCTION OF PYROLYSIS TIME, TEMPERATURE, AND SUBSTRATE

Pyrolytic carbon films were produced at temperatures between 728 and 1100-degrees-C on macor substrates. Scanning electron microscopy indicated that film morphology varied with temperature and that the most adherent films were obtained at 926-degrees-C. Increases in pyrolysis time resulted in thicker, less adherent films. Rate of charge transfer were determined via cyclic voltammetry for the ferri/ferrocyanide redox couple. Films generated at 728-degrees-C exhibited sluggish charge-transfer kinetics. Films fabricated at other temperatures displayed rate constants between 3.8 and 15.4 X 10(-3) cm/s. Electrode capacitance decreased with increased pyrolysis temperature. Film formation did not occur on quartz substrates unless pyrolysis temperatures were in excess of 783-degrees-C. Two distinct types of film were formed on quartz, depending on pyrolysis temperature. Rates of charge transfer for both types of film were similar to those obtained for macor-based films, but electrode capacitance was significantly higher for one of the film types. Films obtained on quartz at any temperature were much less adherent than those formed on macor.