Study On Properties Of Copper-iron Composite Powder Prepared By Mechanochemical Method

In the early stage,iron powder and copper powder are often mechanically mixed in the preparation process of oil bearing.Due to the segregation tendency of iron and copper mixed powder,the powder composition distribution is not uniform,which affects the quality of parts.Therefore,the development of high performance iron copper base oil bearing raw materials has important practical significance and industrial application value.Copper-iron coated composite powder can effectively solve the problem of uneven distribution of direct mixed components of copper-iron powder.However,the existing preparation methods of copper-iron composite powder have some problems,such as uneven coating by mixed diffusion method and unfriendly environment by chemical replacement method,which limit its further development.A simple and environmentally friendly preparation technology of copper-iron composite powder for oil bearing was developed.The effects of raw material properties,mixing process and reduction process on the properties of composite powder were studied.The properties of composite powder prepared by chemical replacement method and ball milling method were compared.At the same time,the influence of different metal elements on the properties of powder was studied.Copper-iron composite powder was successfully prepared by mechanochemical method with reduced iron powder and cuprous oxide powder as raw materials.It maintained the irregular sponge-like morphology of raw iron powder,and fine Cu particles were densely distributed on the surface of Fe particles.The microstructure was core-shell structure.With the increase of mixing speed and mixing time,the bulk density of composite powder increases and the fluidity improves.When the mixing speed is 1200 r/min and the mixing time is 4 min,the performance of copper-iron composite powder is the best.With the increase of reduction temperature,the bulk density of the composite powder increases and the flowability improves.When the reduction temperature is 700?,the radial crushing strength of the composite powder sintered body is the largest.When reduction time exceeds 2 h,the radial crushing strength of composite powder sintered body does not change obviously.The copper-iron composite powder prepared by mechanochemical method has better compressibility.Compared with the composite powder prepared by chemical replacement method,the blank density is 0.14?0.22 g/cm3 under the same pressing force(200?400 MPa).Under the same blank density(5.40?6.20 g/cm3),the strength of the blank was nearly 50%higher.Compared with the composite powder prepared by ball milling,the blank density is 0.24-0.36 g/cm3 lower under the same pressing force(200?400 MPa).At the same blank density(5.80?6.20 g/cm3),the strength of the blank is slightly higher.In the case of similar sintering density,compared with the powder prepared by ball milling,the composite powder prepared by mechanochemical method has good sintering performance,and the porosity of the powder sintered body is much higher than that of the powder prepared by ball milling.Compared with the composite powder prepared by chemical replacement method,the sintering properties of the two powders are similar.The radial crushing strength of the sintered body is 308 MPa and 306 MPa,and the opening rate is 19.8%and 19.6%,respectively.Trace metal elements were introduced at the interface of copper-iron composite powder.It was found that Ni,Cr and Ti had little effect on the properties of the composite powder.With the increase of Sn content,the coating effect of the composite powder was improved,and the radial crushing strength of the composite powder sintered body increased significantly.When the Sn content was 2.0%,the radial crushing strength of the sintered body was 402 MPa,which was 30.52%higher than that of the sintered body without metal elements(308 MPa).