Effect of some additions on the microstructure and mechanical, fatigue, and friction properties of sintered lead bronze
In an investigation into the effect of Zn, Ni, As, P, Fe, Sn, and Sb on the properties of sintered lead bronze with 30% Pb it was established that all the additions except iron and phosphorus increase in varying degrees the strength, hardness, and resistance to fatigue stresses of the material. All the additions adversely affect its coefficient of friction.
Individual elements affect the properties mentioned above by changing both the structure of the bronze and the dihedral angles between its copper and lead constituents. With tin and antimony additions, dihedral angles of more than 60° are recorded; as a result, the resistance to fatigue stresses and strength of the bronze increase, but its coefficient of friction also rises.
With structures characterized by dihedral angles smaller than 60°, no significant changes in properties are observed compared with the alloy without an addition; in fact, properties may actually be lowered. On the basis of the results obtained, it may be recommended that, taking into account the required load-carrying capacity and bearing life, tin or antimony should be added to lead bronze in amounts necessary for improving the friction properties of parts.
KeywordsIron Copper Microstructure Fatigue Phosphorus
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