ALUMINIUM NITRIDE COATING DEPOSITION PROCESS Russian patent published in 1997 - IPC

FIELD: manufacture of supporting members for slow-wave systems of traveling-wave tubes. SUBSTANCE: process includes deposition of aluminium nitride coating on molybdenum rod pre-etched with mixture of hydrogen peroxide and caustic soda (1-5%) and annealed in ammonia for at least 15 minutes at deposition temperature. Nitride aluminium coating thickness amounts to 50-200 mcm at thickness of separate layer 5-15 mcm. Prior to depositing next layer, entire element is cooled down to room temperature and annealed with ammonia at deposition temperature for at least 15 minutes. Heat conductance of coating is minimum 100 W/m K, dielectric strength, 50 kV/cm, adhesion, not worse than 2 kg/sq.mm. EFFECT: reduced through porosity and improved layer-to-layer adhesion. 1 dwg, 1 tbl