Process for surface hardening of refractory metal workpieces

Details Process for surface hardening of refractory metal workpieces Process for surface hardening of refractory metal workpieces

1993-11-29

1995-03-21

Silverberg, Sam

Metal treatment

Process of modifying or maintaining internal physical...

Carburizing or nitriding using externally supplied carbon or...

148223, 148238, 148281, C23C 810

Patent

active

053992075

ABSTRACT:
A process and apparatus for forming a hardened outer shell (40) on a refractory metal workpiece (36) preferably heated in a fluidized bed of metallic oxide particles (38) in an environment of an inert gas and a reactive gas with the reactive gas either oxygen or nitrogen. The workpieces (36) are heated in the fluidized bed to a temperature between 800.degree. F. and 1600.degree. F. for a period of over two hours to form hardened outer shell (40) in two layers (42, 44). Outer layer (42) is an oxide or nitride layer having a thickness (T1) between 10 microns and 25 microns. Inner layer (44) is a case hardened layer of the refractory metal having a thickness (T2) between 25 microns and 75 microns. In one embodiment (FIG. 3 ) workpieces (56) may be cold worked by peening from finely divided metal oxide particles (54) to provide a uniform surface texture for subsequent hardening.

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