Method and apparatus for carbon coating and boron-doped carbon coating a

Abstract

A gravity assisted open system for coating porous refractory substrates with a highly uniform layer of graphite or other material. Pyrolytic dissociation of downwardly flowing precursor gases in an inert atmosphere, countercurrent to an upward direction of transport of the porous refractory substrate, promotes infiltration of dissociated species of the precursor gases into pores and cavities of the porous refractory substrate. The infiltrated species collide with and condense on the surfaces of the pores and cavities of the upwardly moving porous refractory substrate to form a homogenous coating having particular electrical, mechanical, and optical properties. The open configuration of the system allows coating of specimens of porous refractory substrate material at substantially atmospheric pressure, which reduces startup and shutdown transient conditions which affect the uniformity of the coating and its properties, and which provides for coating porous refractory substrates at production rates.