Process for surface hardening of refractory metal workpieces
US5399207A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 29, 1993 |
| Grant date | Mar 21, 1995 |
| Priority date | — |
| Expiry date | Nov 29, 2013 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C8/28
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.