| 摘要 |
A metallic powder consisting of Mo, 0-35% W, 0-10% iron group metal, 0-2% metal oxide which cannot be reduced by hydrogen is composed of porous particles 100% of which are -100 mesh (Tyler), at most 2% of which are +150 mesh and at most 2% of which are -325 mesh: the powder has an angle of repose of less than 45 DEG to the horizontal. The particles each have voids which may or may not open into their outside surfaces; they may be produced by melting molybdenum trioxide (with or without other oxides), forming and solidifying droplets from the melt and reducing the oxide droplets with hydrogen in two stages. The powder may be used for spraying with an oxyacetylene or plasma spray gun.ALSO:In the production of a flame-spraying powder (see Division C7) MoO3 spheres are produced by passing a stream of molten MoO3 flowing from a 3/8 inch opening in the bottom of a crucible, downwardly through a 2-inch i.d. collar provided with three axially spaced circumferential rows of inwardly directed air inlets. The air jets so produced inclined downwardly at about 30 degrees to the collar axis. |
