Chemical vapour deposition processes for coating bores of tubes - tantalum coating obtd. by decompsn. of its chloride

摘要

Process for coating hollow bodies, esp. tubes, comprises a chemical vapour deposition process in which the tube is heated in zones to the deposition temp. so that the coating only occurs in the zone at the required temp. In the pref. process, metal-acetylacetonates, -carbonyls or -halides are decomposed in a stream of carrier gas, esp. TaCl5 in a stream of H2 in zones heated to above 600 degrees C to obtain a deposit of Ta, the length of the zones being 1-5 cm. Suitable for coating the bore of a hollow body with substances which cannot be deposited by electroplating, e.g. steel tubes to specification V2A or V4A coated internally with Ta and used in gas-chromatography.