Chemical vapor deposition of ZrC in small bore carbon-composite tubes

Process conditions are described for the chemical vapor deposition of ZrC from ZrCl/sub 4/--CH/sub 4/--HCl--H/sub 2/--Ar vapor over the temperature range 1320 to 1775 deg K. From an analysis of the process conditions (initial composition of coating gas, axial temperature profile along the tubes, total pressure, and length of deposition time), the subsequent ZrC coat thickness profiles and thermodynamic data, an equation expressing the variation of the axial rate of ZrC deposition is derived. This expression can be used for the estimation of process conditions required to yield a specified ZrC coat profile. Variations of the chlorine and oxygen contents, lattice pararmeter, microstructure of the ZrC deposit and thermal expansion coefficient as a function of deposition temperature are described. (11 figures, 3 tables) (auth)