ELECTROCHEMICAL SYNTHESIS OF CERAMIC MATERIALS .4. ELECTROPHORETIC DEPOSITION OF METAL NITRIDE CERAMIC PRECURSORS

We have prepared metal nitride ceramic precursors by anodic dissolutio n of the corresponding metal in liquid NH3 electrolyte solutions and t hen deposited coatings of these precursors onto n-Si substrates by ele ctrophoresis. X-ray diffraction and electron microscopy indicate that calcination of the precursor-coated substrates yields coatings of AlN, delta-NbN, and Ni3N. Precursor coatings are formed by applying fields greater than 10 V/cm between electrodes in a CH3CN suspension of the precursor. The positively charged precursor particles deposit selectiv ely on the cathode. Subsequent calcination in flowing NH3 or Ar yields the metal nitride coating. The Ni3N coating was prepared by calcining the precursor at 375 degrees C in NH3, while the AlN and NbN precurso r coatings were prepared by calcination at 1100 degrees C in NH3 and 8 00 degrees C in Ar, respectively.