Reserch On Friction And Wear Properties And Thermal Expasion Of Al-Sn Bearing Alloys

Tin aluminum alloy is a kind of high property bearing-material. These alloys present good resist adhesion properties; good wear resisting, corrode-resist properties and excellent conform-embed properties. So, they have been substituted for such wear-resisting materials as brass and Babbitt metal. But, how much the content of tin in the kind of alloy is the best properties have different points. The present work deals with the friction-wear properties of 3%—30% Sn-content Al-based alloys at room temperature and determined the thermal expansion of Al-Sn-Cu bearing alloy-AlSn6Cu,AlSn20Cu,AlSn30Cu between 30 — 150℃. A new kind of 6% TiB₂/Al-10Sn composite was fabricated by LSM method.The hardness, friction coefficient and friction-wear performance and thermal expansion of different Sn-content Al-based alloys were carried out on material testing system, abrasion testing machine, metallographic microscope, image-analyzer and thermal expansion equipment.The results show that: (1) 9% Sn-content Al-based alloys have fully eutectic organize, reticulate Sn surround Al crystal. With the increasing of Sn-content, Sn atoms get together into sphericity and crystals α (Al) crystals are refined. (2) The microanalyses of the TiB2/Al-10Sn composite revealed that TiB₂ particles are well distributed in the α (Al) matrix, the mean size of TiB₂ particles which is close to that of equiaxed polyhedron is < 1 μ m. But the micro-cluster phenomenon of TiB₂ particles occurs in the interface between α (Al) and eutectic tin. Primary α (Al) crystals are refined. β (Sn) phases are solidified around TiB₂ particles and distributed in the grain boundary as network structure. The "peritectic-type" structure of TiB₂ surrounded with tin is formed by homogenization. Several TiB₂particles are surrounded by tin phase and the whole organization become olivary. (3) It is shown that the friction coefficient of Al-Sn tends to decrease and the bearing capacity of alloys reduces with the increasing content of Sn. The aluminum alloys with 9% Sn content has the best wear-friction properties at room temperature. (4) with the increasing content of Sn the 3 (Sn) phase increasing coefficient of expasion decrease. (5) The dramatic changes of expasion coefficient of the alloy with temperature dependence decrease with increasing of copper content which has higher melting-point .Copper dissolving in the α (Al) phase brings about α (Al) lattice dropping.Guangxi is abundant in non-ferrous mineral resources, especially in Tin and Aluminum. So the present work is significant for exploitation and utilization of resources as well as the development of economy in Guangxi.