This describes the manufacturing method of Steel sintered and alloyed frictional materials including a lot of lead. Steel sintered alloy and copper sintered alloy and steel and copper sintered alloy have been mainly used as a sintered alloy, used for veering or frictional materials, but there have been several problems, they have not shown excellent suitability with the opponent frictional material, they have weak abrasion-resistance and load-resistance also they can`t be used in a humid environment, because they got rust easily.
In contrast to above, it is known that steel and copper sintered ally is superior to other sintered alloies in various features, including abrasion-resistance and load-resistance. Since lead`s melting point(M.P.:325) is conspicuously lower than that of steel, if it is sintered with high-temperature, as when mixing and sintering steel and lead powder with other component like copper, most part of lead are vaporized and isolatedly abstracted. Thus we are unable to make them contain sufficient lead for sintered alloy.
For example, when mixing lead powder as a raw material in proportion of 20% in a former method, the remaining lead content after the completion of sinter is about 5%, it is impossible to improve lead content to over 15% and to obtain sufficient lead contenting effect with former sintered alloy method. As described above, the former manufacturing method had several problems, when sintered with high temperature, the wasted material is inevitable, as it is impossible to prevent the vaporization of lead. Especially vaporized lead steam adheres to the refrigerating part even with the concentration of under 0.2% in air and causes the damage to equipment and makes pollution, including lead poisoning. Therefore, the purpose of this high lead content sintered alloy, while preventing the vaporization and the isolated abstraction of lead when sintered with high temperature.