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Preparation of lead-free free-cutting graphite brasses by graphitization of cementite 被引量:1
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作者 卓海鸥 唐建成 +1 位作者 薛滢妤 叶楠 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第10期3252-3257,共6页
Graphite brasses were prepared by graphitizing annealing of cast brasses containing cementite particles,which were in-situ formed during the fasting process.The eutectic cast iron as carbon source was added into commo... Graphite brasses were prepared by graphitizing annealing of cast brasses containing cementite particles,which were in-situ formed during the fasting process.The eutectic cast iron as carbon source was added into common brasses by casting.SEM and EDS were used to analyze the microstructure of graphite brasses,and the relationship between the microstructure and machinability was investigated.The results show that graphite particles are formed by the decomposition of cementite particles in cast brasses.The graphite particles are uniformly dispersed in the brass matrix with the average size of 5.0 μm and the volume fraction of ~1.1%.The machinability in the graphite brass is dramatically increased relative to the common brass,because of the lubricating properties of graphite particles and its role in chip breaking.The workpiece surface of the graphite brasses chips is smooth and burr-free,and the chips of graphite brasses are short(C-shape) and discontinuous,which is much better than that of the long spiral chips of common brasses. 展开更多
关键词 lead-free graphite brass graphitization annealing microstructure machinability
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Cementites decomposition of a pearlitic ductile cast iron during graphitization annealing heat treatment 被引量:5
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作者 Min-qiang Gao Ying-dong Qu +2 位作者 Guang-long Li Jun-hua You Rong-de Li 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2017年第8期838-843,共6页
Cementites decomposition of a pearlitic ductile cast iron during graphitization annealing heat treatment was investigated.Fractographies and microstructures of heat treated samples were observed using a scanning elect... Cementites decomposition of a pearlitic ductile cast iron during graphitization annealing heat treatment was investigated.Fractographies and microstructures of heat treated samples were observed using a scanning electron microscope and mechanical properties were measured by a universal tensile test machine.The results indicated that during isothermal annealing at 750°C,the tensile strength of pearlitic ductile cast iron was increased to a peak value at 0.5h,and decreased gradually thereafter but the elongation was enhanced with the increase of annealing time.Moreover,the diffusion coefficient of carbon atoms could be approximately calculated as 0.56μm2/s that could be regarded as the shortrange diffusion.As the holding time was short(0.5h),diffusion of carbon atoms was incomplete and mainly occurred around the graphites where the morphology of cementites changed from fragmentized shape to granular shape.In addition,the ductile cast iron with tensile strength of 740MPa and elongation of 7% could be achieved after graphitization annealing heat treatment for 0.5h.Two principal factors should be taken into account.First,the decomposition of a small amount of cementites was beneficial for increasing the ductility up to elongation of 7%.Second,the diffusion of carbon atoms from cementites to graphites could improve the binding force between graphites and matrix,enhancing the tensile strength to 740 MPa. 展开更多
关键词 Pearlitic ductile cast iron Cementite decomposition Diffusion Carbon atom Graphitization annealing heat treatment
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Preparation and properties of polycrystalline silicon seed layers on graphite substrate 被引量:2
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作者 李宁 陈诺夫 +1 位作者 白一鸣 何海洋 《Journal of Semiconductors》 EI CAS CSCD 2012年第11期28-31,共4页
Polycrystalline silicon(poly-Si) seed layers were fabricated on graphite substrates by magnetron sputtering. It was found that the substrate temperature in the process of magnetron sputtering had an important effect... Polycrystalline silicon(poly-Si) seed layers were fabricated on graphite substrates by magnetron sputtering. It was found that the substrate temperature in the process of magnetron sputtering had an important effect on the crystalline quality,and 700℃was the critical temperature in the formation of Si(220) preferred orientation. When the substrate temperature is higher than 700℃,the peak intensity of X-ray diffraction(XRD) from Si(220) increases distinctly with the increasing of substrate temperature.Moreover,the XRD measurements indicate that the structural property and crystalline quality of poly-Si seed layers are determined by the rapid thermal annealing (RTA) temperatures and time.Specifically,a higher annealing temperature and a longer annealing time could enhance the Si(220) preferred orientation of poly-Si seed layers. 展开更多
关键词 polycrystalline silicon graphite rapid thermal annealing preferred orientation
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