increased. However, the compressive strength was decreased. This was because according to the increase of the amount of Mn, the area ratio of the sulfides was
increased, and the bonding strength between the metallic particles was decreased. In addition, according to the increase of the amount of Mn in the iron powder, the iron powder was hardened, and the compressibility was decreased, whereby the compressive
strength was decreased. In general, Mn is one of elements that improve the hardenability. Nevertheless, since the amount of S was supersaturated with respect to the amount of Mn, Mn for improving the hardenability was hardly obtained, whereby the
effect of Mn for improving the strength was not obtained. Therefore, in the sample of the sample No. 20, the compressive strength was greatly decreased. Accordingly, thethe values of the sample of the sample No. 08 in the First Example are also shown in Tables 5 and 6.

As shown in Tables 5 and 6, when the amount of Cu in the overall composition was increased by increasing the amount of the copper powder, the amount of the iron sulfide powder was decreased, whereby the amount of the sulfides was decreased. In
addition, a part of the amount of Cu formed sulfides, but the specific weights of the copper sulfides are greater than those of the iron sulfides, whereby the area ratio of the sulfides was decreased. Nevertheless, when the amount of Cu was in the range
described in the Third Example, sufficient amount of sulfides were obtained, and frictional coefficients were low.

According to the increase of