| 摘要 |
Oxynitriding (Nitroxidizing) wherein a ferrous workpiece is contacted at least partially simultaneously by a nitrogen-containing molecule (usually ammonia) and by oxygen (generally from steam or water vapor) in a furnace, preferably a fluid bed furnace, to provide a roughened porous outer layer comprising an Fe3O4 layer on top of a nitride layer. These layers provide sufficient roughening and porosity to hold a protective coating e.g. the polysiloxane coatings of U.S. 586,963 or those of U.S. 756,774 or other protective coatings, providing a high resistance to ASTM B117 salt spray test. This eliminates the two steps and related switching apparatus of ferritic nitrocarburizing. |
