| 摘要 |
The present invention discloses novel nitrogen-hydrogen based atmospheres for sintering steel components in continuous furnaces with consistent quality and properties while prolonging the life of the wire mesh belts, reducing maintenance costs, and improving furnace productivity. Specifically, it discloses the use of a controlled amount of an oxidizing agent such as moisture, carbon dioxide, nitrous oxide, or mixtures thereof along with nitrogen-hydrogen atmospheres to (1) sinter steel components with consistent quality and properties, (2) prolong life of wire mesh belts, (3) reduce downtime and maintenance costs, and (4) reduce the formation of soot in the furnace. The use of a controlled amount of an oxidizing agent has been unexpectedly found to form a protective and adherent oxide layer on the belt material, eliminate complete reduction of the belt material in the heating zone of the furnace, and prevent sticking of sintered components on the belt material, all of which are responsible for significantly increasing belt life by reducing (1) erosion of the belt material caused by cyclic oxidation in the preheating zone of the furnace or in the ambient atmosphere outside the furnace and reduction in the high heating zone of the furnace, (2) embrittlement of belt material caused by the formation of metal carbides and nitrides, and (3) degradation of belt material by splashing of foreign material from parts being processed onto the belt. The amount of an oxidizing agent added to the nitrogen-hydrogen atmospheres to precondition belt material prior to its use for sintering and to sinter steel components is controlled in such a way that atmospheres become oxidizing to the belt material but reducing to steel components being sintered, specifically in the high heating and cooling zones of continuous furnaces.
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