Graphite moulding coated with metal carbide or carbonitride - esp. graphite boat coated with zirconium carbide and used to hold samples in atomic absorption spectroscopy

摘要

A carbide or carbonitrite of Zr, Ti, Nb, Hf or V is formed by first immersing the moulding in an acid aq. soln. of a salt of the metal, and using a bath voltage of 3-8 volts so the graphite moulding is coated with the metal during an electrolysis time of 1-2 hrs., followed by washing the coated moulding with pure water. The coated moulding is next placed in a furnace for drying in an inert gas atmos. at 380-400 degrees K, and then heating at 5-20 degrees K per sec. to 2500-3300 degrees K; the moulding is held for 10-30 secs. at the latter temp. The moulding is made of compacted graphite with a smooth surface possessing only slight porosity; and is provided with an adherent, wear-resistant coating.