Abstract
This investigation was undertaken to determine whether or not the gases are enclosed in residual pores of sintered iron. The gas analysis was carried out by the vacuum-fusion method and by the solution-distillation method.
Carbonyl iron powder contains about 1600 p.p.m. of oxygen, as oxide films on powder particles. When the powder compact was sintered in hydrogen at 1200°C, the oxide film was mostly reduced within 1 min. to produce water vapour, which desorbed through the pores to the outer surface. It was suggested, therefore, that the air or nitrogen is not enclosed in residual pores. Approximately 10200 p.p.m. oxygen were detected in sintered iron, which had been cooled to room temperature in hydrogen after sintering. These oxygen contents correspond to the variation of surface area including the inner surface of open pores, which may be explained by assuming that the inner surface of open pores was quickly oxidized in air at room temperature. However, small amounts of nitrogen were not removed by sinteririg in hydrogen.
From the above results it maybe suggested that residual pores in sintered iron contained hdyrogen of about 1 atm.
