EFFECTS OF TEMPERATURE AND REAGENT CONCENTRATION ON THE MORPHOLOGY OF CHEMICALLY VAPOR-DEPOSITED BETA-TA2O5

Crystalline beta-Ta2O5 coatings mere deposited on hot-isostatically-pressed Si3N4 by reacting TaCl5 with H-2 and CO2 in the temperature range of 1000 degrees-1300 degrees C and at a pressure of 660 Pa, The Ta2O5 coatings generally consisted of well-coalesced 2-3 mu m grains, resulting in the formation of a nonporous coating morphology. However, the presence of microcracks on the as-deposited surface was consistently observed, The surface morphology, texture, and growth rate of the coatings were examined as a function of deposition parameters.