Abstract
The present report is concerned with experiments on the infiltrating phenomena of silver, copper and 10%tin-bronze infiltrants into sintered iron skeletons made of three types of iron powders ; that is, (A) electrolytic iron powder made by crashing the electrolytic iron plates, (B) ore reduced iron powder made by crashing the carbon-reduced magnetite ore, (C) mill-scale reduced iron powder made by crashing the carbon-reduced mill-scale of rimmed steel. The results of the experiment can be summarized as follows :
1) In the case of silver, which shows no alloying reaction with iron :
a) With the complexity of the forms of the iron powders, the pore structures of the skeletons increases in complexity, and consequently the liquid silver decreases in infiltrativity. Infiltration can be performed by using, in the decreasing order of the degree of infiltrativity, (A), (C) and (B) powders.
b) The process of infiltrating liquid silver into the skeletons can generally be divided into the following two stages : that is, first the liquid spreads over the surface of the skeleton, and then penetrates into the skeleton. This tendency is most marked when (A) is used. However, the low compactibility of this powder is liable to cause hair cracks in the surface layer of the skeleton.
c) Adding a small amount of tin, which shows alloying reaction with both iron and silver, to the iron skeletons, fairly increases the infiltrativity of silver into the skeleton.
2) In the cases of copper and 10%tin-bronze, which show mutual alloying reaction with iron, their infiltrativity is very high. However, insufficiency in the volume of the liquid in relation to the porosity of the skeleton is liable to cause the liquid to prefer to penetrate into finer pores of the skeleton, leaving pores unpenetrated.
