| Abstract: | A nozzle assembly for a HVOF thermal metallic spray coating system includes
an inner tube, a middle tube and an outer tube which are concentrically
arranged about an axis of the nozzle assembly and are spaced to provide
annular, concentric gas flow passages for oxygen and gaseous fuel along
with a central wire feed passage in an efficient, compact arrangement. A
slotted nib and plug are fitted to the discharge end at the assembly and
defined, together with the middle tube, an annular premix chamber for the
combustible gases, and a plurality of circumferentially spaced mixing
slots and a downstream mix end portion of the nib where complete mixing of
the gases occurs prior to entry into the combustion chamber provided in an
air cap. An annular passage between the air cap and outer tube
communicates with a high pressure air source for establishing an envelope
of air against the inside surface of the air cap to serve as a protective
barrier layer from the atomized metal. |