A New Preparation Method In Tin-babbitt And Its Effects On Microstructures And Properties

In view of the remarkable influnence of melt states on its solidified behaviors, microstructres and properties, this paper has discussed the existing of the temperature-induced melt structre transition (MST) and its reasonable explanation in tin-babbitt alloys which are widely used in engineering. Combining proper melt overheating and cooling conditions, the effects of different melt states on solidified microstructures and related properties have been investigated. In all, controlling melt states by melt overheating is used in this article to explore new tin-babbitt alloys preparation methods and its effects on microstructures and properties. Contents and results are as following:(1) The resistivity-temperature (p-T) behaviors of the B83, B89 and B92 ternary Sn-Sb-Cu alloys in multiple heating and cooling processes have been explored. Results sugguest that the three alloys all exisit abnormal changes at their own special temperature ranges in p-T curves which show different parterns. There is a low temperature reversible MST and a high temperature irreversible MST in B83 and B89 melt, while only an irreversible MST exsits in B92 melt.(2) According to the irreversible liquid-liquid transition infornation, the melt overheating temperature and cooling condtions in tin-babbitt alloys are properly selected and the effects of different melt states on solidification have been discussed by the solidification thermal alsysis, metallograph, XRD and EDS. Results indicate that the melts undergone irreversible MST obtain a larger undercooling in each air cooling solidification stages of all three alloys. In all cooling conditions, the microstructures of samples solidified from the melt undergone irreversible MST are refined with different degree and distributed more uniformly. However, with cooling rate increasing, the effects of melt states on microstructures tend to weaken. The melt states modification has no effects on solidificaton phases, but it causes different Sb element content in matrix.(3) Basing on the exloration in microstructures, the effects of melt states on hardness, tension properties and tribological properties in tin-babbbitt alloys are studied. The Vikers hardness of the alloys undergone the irreversible MST are all improved to different degrees whether in air cooling or cooper tube cooling. Tension results indicate that the effects of refined grain strengthening make the samples which have experienced the irreversible MST prossess higher mechanical properties, such as tensile strength and ductility. Under the dry sliding and oli-lubricated sliding, the B83 specimens undergone the irreversible MST show low friction coefficient and low wear which suggests longer life and better work properties.The results in this article have important significance and reference value for innovation in babbitt alloys preparation methods and improving their properties and service reliabilty.