초록 ▼

A method of coating a surface using a plasma arc torch comprises directing a plasma plume externally from a discharge end of the plasma torch toward the surface, positioning a powder injector proximate the plasma plume to introduce ceramic oxide powder particles at a size less than 20 microns diamet

A method of coating a surface using a plasma arc torch comprises directing a plasma plume externally from a discharge end of the plasma torch toward the surface, positioning a powder injector proximate the plasma plume to introduce ceramic oxide powder particles at a size less than 20 microns diameter into an outer mantle of the plasma plume so that the powder particles are confined in the outer mantle, directing first and second gas jets at the plasma plume downstream of the powder injector position and on opposite sides of the plasma plume to enhance entrainment of the injected powder particles in the outer mantle, circulating the powder particles in the outer mantle of the plasma plume for a residence time to heat the powder particles to melt them without substantial vaporization, and depositing the melted powder on the surface as a dense coating having closed porosity.

대표청구항 ▼

[ We claim:] [1.] Apparatus for coating a surface, comprising:a) a plasma torch having a discharge end from which a plasma plume is directed toward said surface, andb) a powder injector having a powder supply passage and a powder discharge passage having a generally elliptical cross sectional shape

[ We claim:] [1.] Apparatus for coating a surface, comprising:a) a plasma torch having a discharge end from which a plasma plume is directed toward said surface, andb) a powder injector having a powder supply passage and a powder discharge passage having a generally elliptical cross sectional shape with a major and minor passage dimension and with a reduced cross-sectional area as compared to that of said powder supply passage proximate a particle injection region of said plume, said powder discharge passage being oriented at an angle between about 30 and 60 degrees relative to an axis perpendicular to a longitudinal axis of said torch for introducing powder particles in the size range less than about 20 microns diameter into an outer mantle of the plasma plume.