Abstract
The sintering process of plain Iron compacts and Iron-Carbon compacts was investigated by thermal balance and dilatometer during thermal cycle. The effects of moisture contents in hydrogen atmosphere were observed ; A atmosphere with 1.7-1.9 mg/L moisture content, B with 0.2-0.3 mg/L. The Mechanical and physical properties of sintered compacts were measured. The results were as follows.
1) Dimensional change
The specimens containing graphite showed lower shrinkage than plain iron. The shrinkage was greater with A atmosphere than with B atmosphere.
2) Weight change
The weight continued to decrease up to about 900°C, owing to degassing, desorption of moisture and reduction of oxide on the surface of iron powder. Above that temperature, the gassification of graphite by hydrogen was observed.
3) Mechanical properties
Higher strength was obtained for specimens sintered in A atmosphere and their graphite contents were as high as 1%.
4) Carburization
The carburization rate was greatly influenced by the moisture content in hydrogen. In the A atmosphere, the formation of carbide was pronounced, with decarburized layer as thick as 1.6mm. On the contrary, in the B atmosphere, the decarburized layer was very thin and much carbon was left uncombined.
