Preparation And Study On New Cu-based Self-lubricating Material

For satisfying operation of components and parts in the atmosphere of avoiding oil pollution and in the place needing permanent lubricating, preparation of new high-performance cu-based self-lubricating materials not only have science significance but also have important application prospect. Because of widespread application and the better wear property of the cu-based self-lubricating materials, copper is used to be matrix with reinforced elements such as Ni, Sn; Ceramic enhanced phases such as W, SiC and nanometer Al2O3; Graphite, MoS2 or the mixture is added in to the matrix as solid lubricant. The cu-based self-lubricating materials are successfully prepared by general powder metallurgy technology. In the experiment, preparation process, moulding craft, material structure and mechanical properties, and self-lubricating mechanism of the experimental samples were studied with Metallurgical microscope, Scanning Electron Microscope, X-ray diffraction, Pressure tester, Friction and wear tester, and HV-hardness tester and other research techniques. With the results as follows:1) Experiment designed and prepared the new copper-based self-lubricating materials, which taking Cu-Ni-Sn-Pb atomized alloy powder as matrix, adding different content graphite with Owt%, 1wt%,2wt% as solid lubricant. The optimized sintering process is: 910℃and the sintering time is 4hours. With the increased of graphite content, the hardness decreased from 80.1HV to 35.7HV; the crushing strength decreased from 590.3MPa to 262.7MPa; the density decreased from 6.89g/cm3 to 6.69g/cm3; the friction coefficient decreased from 0.36 to 0.16; The wear resistance of samples with lwt% graphite is the best, the wear losses was 1/20 of non-graphite samples.2) At constant 2wt% graphite condition, adding the 14μm SiC, which content is 1wt% and 2wt%, and the 75μm SiC, which content is 1wt% as strength phases. We prepared the copper-based self-lubricating materials. The enstrength effect was better when the strength phase is 1wt% 14μm SiC. The density was 6.73g/cm3, the hardness was 61.2HV and the crushing strength was 480MPa. The wear resistance was the best as well. We prepared the self-lubricating material with porosity from 18%-27%. The density decreased from 5.90g/cm3 to 6.60g/cm3; the crushing strength increased from 170MPa to 251MPa; the hardness increased from 24.2HV to 43.0HV; The wear losses decrased 7/8.3) Taking Cu-Ni-W-Y2O3-MoS2-SiC mixture powders as matrix, adding different graphite including 3wt%,3.5wt%,4wt%,4.5wt% and 5wt% as solid lubricant. We prepared the high-graphite content copper-based self-lubricating materials. With the increased of the graphite content, the hardness decrease from 26.7HV to 19.8HV; the crushing strength decreased form 189MPa to 103MPa; the density decrease from 6.19g/cm3 to 5.99g/cm3. The friction coefficient is about 0.18; the wear losses increased slowly with the increasing of graphite.4) We prepared the self-lubricating materials, which taking the mixture powders of Cu-Ni-Y2O3-MoS2-Graphite as matrix, adding different content nano-Al2O3 including 0wt%,1wt%,2wt%,3wt% and 4wt% as dispersion enstrength phase, The density decreased with the addition of nano-Al2O3, but the hardness and crushing strength increased to 2% firstly, then decreased with more nano-Al2O3. The property is the best when the addition is 2%, that is:the density is 6.16g/cm3; the hardness increased to 35.1HV from 23.7HV; the crushing strength increased to 276MPa from 189MPa; Friction coefficient of the material with the mixture of graphite and MoS2 is small and stable, that is about 0.12. The wear losses was the best with 2%Al2O3, which is 1/7-1/8 by contrasting the samples with non-nano-Al2O3.5) The copper-based matiral, which were refored by Ni, Sn and nano-Al2O3 by dispersion strengthening, and were added graphite and MoS2 as solid lubricant, have definite self-lubricating property. Strengthening phase improve the anti-scaping ability, lubricating phase reduce the intensive adhesion, the appropriate mixture ratio of them influence the effect of self-lubricating.