Hydrogen Reduction Of Oxides Research Articles

PM grade iron powders by hydrogen reduction of oxides from pickling bath recovery plants

A process has been developed for the production of PM grade iron powders by the reclamation of iron oxides from the hydrochloric acid pickling baths used in rolling mills followed by hydrogen reduction and milling. Fine iron oxide obtained in a Ruthner plant was found to yield iron powder comparable to commercial sponge iron powder. The coarser iron powder produced from Lurgi iron oxides were also found to offer quite respectable properties for PM applications if a carefully balanced reduction and milling treatment is applied.

鉛および鉛合金の鉄に対するぬれ性と溶浸性

As a preliminary experiment, influence of oxygen in atmosphere on the wettability of Pb to Fe plates was investigated. At constant oxygen partial pressure in atmosphere, wettability and infiltration behavior between Pb or its alloys and Fe plates or Fe green compacts were also examined. Results obtained were as follows:(1) Wettability of Pb to Fe plates was significantly affected by oxygen in atmosphere; wetting proceeds successively with decreasing oxygen partial pressure. This is explained by the hydrogen-reduction of oxides on Pb drops and Fe plates. At constant oxygen partial pressure, wetting proceeds with raising temperature, this being explained mainly by the reduction of surface tension of liquid Pb.(2) Addition of Sn to Pb is efficient in wetting to Fe plates, especially at lower temperature. In contrast to this, addition of Cu is effective at higher temperature. Addition of both Sn and Cu to Pb is most efficient in wetting to Fe plates over a range from lower and higher temperature.(3) Infiltration of Pb to Fe green compacts is, as is in the wettability, difficult, but the addition of Sn or Cu to Pb improved the infiltration. Addition of both Sn and Cu improved the infiltration preferencially. Once these infiltrants start to penetrate into Fe green compacts, infiltration is accomplished completely in a few minutes.

Iron Whisker Surface Rearrangements Resulting from the Hydrogen Reduction of Oxides and from Thermal Etching

The hydrogen reduction of high-temperature oxidation products grown on iron whiskers produces iron surfaces whose topography depends on the orientation of the surface that was oxidized. The different topographies for {100} and {110} surfaces are shown, and the dependence is further illustrated on the polycrystalline iron surfaces which result from the heating of a single-crystal α iron whisker through its transformation temperature of 910°C. Rearranged surfaces covered with parallel striations and unusual dendritic surface structures are shown and discussed. Both the striations and dendrites are the result of thermal etching of a ``polycrystalline'' iron whisker at temperatures between 800°–1200°C.