| 摘要 |
The invention relates to a process for generating a hard oxide layer (Fe3O4) on a surface and in the pores of sintered iron parts. A steam treatment process is known in which, in a sealable furnace chamber, the sintered iron parts are largely freed of atmospheric oxygen by flushing with steam at 370 DEG C and are then treated at 550 DEG C for at least one hour with superheated steam. In this way, a hard oxide layer of Fe3O4 is formed on the surface and in the pores of the sintered iron parts. In addition to the long treatment time, the known process also has the disadvantage that it can only be carried out batchwise in a sealable chamber. These disadvantages are avoided in the process according to the invention by heating the sintered iron parts in a continuous furnace to 370 DEG C-570 DEG C and passing them through a gas mixture with free oxygen, preferably air with a few percent by weight of steam. The air is expediently introduced at the furnace end into the treatment channel and extracted at the furnace inlet. It is then advantageous to adhere to a temperature limit of 370 DEG C in the front part of the furnace, which part has such a length that the passage time of the sintered iron parts is sufficient for complete evaporation of lubricants adhering thereto.
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