Study On The Tribological Characteristics Of Copper-Bismuth With Silver Bearing Materials

With the continuous development of bearing materials, both home and abroad have carried out relevant lead-free copper-bismuth bearing friction and wear properties of materials research. To improve the characteristics of copper-bismuth bearing materials on which the fu Bi phase falling off from the surface of brittle grinding materials, and based on the copper-bismuth bearing materials research, added trace silver elements to the copper-bismuth bearing materials, in order to ease the phenomenon that the fu Bi phase stripping from the grinding crack surface and improve tribological characteristics of bearing materials. Lead-free copper-bismuth bearing materials were prepared by the conventional powder metallurgy method. Study on the mechanics and the tribological characteristics were conducted under different conditions. In order to investigate the friction and wear mechanism of lead-free copper-bismuth with silver bearing, microstructure, fracture and worn surface morphology, the chemical composition of the worn surface are analyzed with optical microscopy, scanning electron microscopy and other means of microscopic analysis.The study showed that with the proper amount of silver metal elements on copper-bismuth bearing materials can obviously ameliorate the antifriction and wear resistance under the condition of dry friction. Adding appropriate content of silver in the copper-bismuth bearing materials have certain effect on the improvement of friction and wear properties under the condition of oil lubrication. Especially with the drops of oil reduced and lubrication effect weakened, silver has a good performance in copper-bismuth anti-friction bearing materials and wear-resistant. Whether it is in the dry or oil-lubricated condition, silver content are best added to0.80wt%.Under the condition of dry friction, since adding Ag can slow down the grinding crack surface spalling of fu Bi phase velocity, more soft phase Bi with low melting retains on the surface of grinding crack. Ag also belongs to the soft phase, so the Ag and Bi in friction surface synergy, is beneficial to reducing the shear strength Ï„b of the contact point, improving the characteristics of copper-bismuth with silver bearing tribological materials. Under the condition of oil lubrication, adding a bit silver also slows down the Bi falling off from the surface of the grinding crack, and makes Bi content on the surface of grinding crack of copper-bismuth with silver bearing materials increased. Suitable content added for Ag can let Ag and Bi have synergy, which further improve the characteristics of copper-bismuth with silver bearing tribological materials, however, Bi content on the surface of grinding crack is still obviously inclined to be less compared with that of dry friction. With poorer lubrication conditions and time of extending of test, Bi content on the surface of grinding crack grows less and less, and the content of Fe gets more and more, meaning that friction and wear become more serious and easier Bi falls off from the friction and worn surface of the grinding crack, and the severer the adhesion wear is.