Teruji Nojiri1, Fusao Hayama2 and Shigeo Oya2
1Graduate School, Waseda University, Tokyo. Present address: Fuji Heavy Industrial Co. Ltd., Tokyo
In a previous paper on the relationship between the sliding wear of lead-bronze and its casting structure, the present authors reported that the wear resistance was the strongest in the equi-axial crystal part, followed by the columnar crystal part and the chilled crystal part in order.
In this paper the wear mechanism of lead-bronze on dry sliding in air was investigated. The specimens were lead-bronze containing 0 ∼ 40%Pb and 0 ∼ 12%Sn, and these were slid on a hardened steel ring without any lubricant.
The results obtained are as follows:
(1) The wear mechanism of lead-bronze can be devided into metallic wear, melting wear and oxidizing wear.
(2) Metallic wear is found in the chilled crystal part or the parts containing little tin and lead in lead-bronze. The wear rate of the specimen is high, but the wear of the mating steel ring is hardly observable.
(3) Melting wear is generally found in a copper-lead alloy (without tin), particularly in a high lead alloy. The wear rate of the specimen is very high, but that of the mating ring is very small. Addition of tin is effective to prevent the wear of this type.
(4) Oxidizing wear is found in the high tin alloys, or alloys containing large amounts of tin and lead. In general, Cu2O is revealed at a low sliding speed and α -Fe2O3 at a medium speed, while a mixture of oxides of lead, copper and iron (PbO, Cu2O and α -Fe2O3) is observed at a high speed. The wear of the specimen is very small, but the wearing behaviors of the mating steel are in a varied with the oxidizing state and the wear rate is high at large.
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