Investigation of wear and fatique behaviour of bronze bearings with low alloy low sn content

Ill ABSTRACT PhD. THESIS INVESTIGATION OF WEAR AND FATIGUE BEHAVIOUR OF BRONZE BEARINGS WITH LOW ALLOY LOW SN CONTENT Hüseyin TURHAN Firat University Faculty of Technical Education Department of Metallurgy 1998, Pages: 100 Intfeis study, the effect ©f B^ Ee and Mn which are added into Sn-bronzes with 5 - 6 % Zn, in increasing amounts, on surface hardness, energy capacity, tension, wear resistance and fatigue life of these materials were investigated comperatively. The specimens prepared were applied SEM, X-Ray diffraction analysis and hardness,tension bending fatigue and dry- friction adhesive wear tests. At the first and second chapters of the study, bronzes and their alloying elements were introducted. At the third and fourth chapters Sn - brozes, Sn - based bearing materials and Pb- additive bearing bronzeswere discussed. At the fifth and sixth chapters information about surfacial behaviours in friction, adhesion wear, contacting surfaces and adhesive wear were presentedIV At the seventh chapter, fatigue mechanisms, fatigue types, and the factors affecting fatigue behaviours of materials were defined. The following chapter deals with experimental studies. At the final chapter, the experimental results were given and dicussed. Finally some recommendations were presented. From the results, it was seen that, P did not effected the wear resistance negatively. In the P - free specimens, the wear resistance decreased with the increase of Fe and Mn content whereas these elements improved the fatigue strength. They also increased the tension strength, surface hardness and fatigue life of the alloys bei forming intermetallic compounds and precipitating among the dendrite arms.Except P the other alloying elements decreased the wear resistance relatively. In the specimens including very hard intermetallic phases, a relationship between wear resistance and surface hardness was determined for adhesive wear. Depending on the increase in Fe and Mn content, a big amount of intermetalic compounds formed among the dendrite arms. Formation of intermetallic phases prevented the formation of brittle (Zn,Cu)S phase. This occurance increased surface hardness and tension strength and thus increasing fatigue life. But after a certain extent of intermetallic phases, the wear resistance decreased relatively. The alloys including intermetallic compounds are preferable for fatigue strength unlike wear resistance. Addition of P caused an increase in fatigue life. Wear resistance however was not influenced very much by the hard phases like SnCu2FeS4, and FeSn2. Fe and Mn decreased the wear resistance relatively while increasing fatigue life considerably. ft was understood that the specimen having the best wear resistance, good fatigue life and mechanical properties was the one with 0,224 % P. With respect to the wear resistance, the specimens having 0,226 % Mn and 1,08 % Fe follewed this respectively. But the fatigue strengths of these alloys increased compared with the other allovs.