Abstract
In powder metallurgy processings, oxide films on the surface of metallic powder particles are generally reduced during sintering. In some cases, however, the oxide films can be used as an important element for obtaining the special performance materials, such as SAP and flaky aluminum sintered compact having unique voltage-current characteristics. In this study, the conditions such as powder particle shape and size (d), relative green density (Dg), and sintering temperature (Ts) for remaining continuous oxide films in aluminum sintered and green compacts were investigated by electrical resistivity measurement .
The results obtained are as follows: (1) The measurement should be carried out under the breakdown voltage at which an electric current suddenly increases in voltage-current characteristic. (2) Semi-quantitative equations for the contiguity (C) of metal/metal or the continuity (1-C) of oxide films were proposed. (3) The continuous oxide films remained easily in the flaky powders as compared to the granular powders, and it was semi-quantitatively clarified that the continuous oxide films in the granular powders tended to remain in the case of smaller d, lower Dg and lower Ts.
