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Quick Search     Adv Search   2015 Vol. 25, No. 02 Published: 2015-04-18   1 The performance improvement and selection of lubricant for production of PM components HAN Feng-lin DOI: 10.13228/j.boyuan.issn1006-6543.20130116 In the production of PM components, admixed lubricant in the metal powder mix is the most common way to achieve the lubrication needed during compaction and ejection of the components. However, the type of lubricant not only influences the compaction, but also the properties of the powder mix as well as the properties of the green component and sintered parts. The most commonly used lubricants were reviewed, and the advances in binder/lubricant systems in the past two decades were introduced. 2015 Vol. 25 (02): 1-7 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 8 Study on the preparation process of MIM stainless steel powder by high pressure water atomization method LENG Dan, ZENG Ke-li, WANG Zhi-yong, SONG Xin-qiang, ZHU Jie, TIAN Xue-na DOI: 10.13228/j.boyuan.issn1006-6543.20140041 Stainless steel powder was prepared by high pressure water atomization method. The influences of nozzle diameter and water pressure on the morphology, oxygen content, particle size distribution and tap density of powder were investigated. The microstructure and properties of samples were characterized by means of laser particle size analyzer, scanning electronic microscope, etc. The results indicate that, the stainless steel powder has small average particle size ([D50] is 8.83 μm, [D90] is 20.80 μm), uniform particle size distribution, low oxygen content and high tap density when the water pressure is 115 MPa and the nozzle diameter is 3.5 mm. 2015 Vol. 25 (02): 8-11 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 12 Research and application evaluation of new magnetic alloy powder for MPC WANG Jun, LU Guang-feng, YU Jin-xia, LIU Gang DOI: 10.13228/j.boyuan.issn1006-6543.20130114 Magnetic alloy powder is the most important factor in magnetic particle clutches and brakes. A new magnetic alloy powder was prepared by gas atomization process, the oxidation resistance and failure mechanism of the powder was discussed. The static testing shows that the new magnetic powder has good physical characters and high temperature magnetic stability; while the dynamic testing shows that the powder has high output torque and good heat resistance. 2015 Vol. 25 (02): 12-19 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 20 Gelcasting and vacuum sintering process of TiC/Fe steel bonded carbide SHI Yong-liang, GUO Zhi-meng, LI Xiu-min, YANG Xiao-cai, QI Cui-fen DOI: 10.13228/j.boyuan.issn1006-6543.20140080 Gelcasting in methylbenzene/HEMA system was successfully employed to manufacture TiC/Fe cemented carbide with complex shape. The effects of monomer content on the structure, density and strength of green and sintered body were analyzed. The results show that the monomer content is the key factor in TiC/Fe gelcasting process. The optimum monomer (HEMA) content is 4.6% (based on the mass of powder). With the optimum monomer content, the green strength is 28 MPa. When vacuum sintered at 1 420 ℃ for 1 h, the transverse rupture strength, density and hardness of specimens are 1 410 MPa, 6.46 g/cm3 and 50 HRC, respectively. The transverse rupture strength and hardness reach 1 670 MPa and 65 HRC after heat treatment. 2015 Vol. 25 (02): 20-24 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 25 Effect of the fine Cr-Fe alloy powder on the microstructure and properties of powder metallurgy steels MOU Nan, LEI Long-lin, XU Ran, TANG Lin, LUO Feng-hua DOI: 10.13228/j.boyuan.issn1006-6543.20140078 The Fe-Cr-Mo PM steel was obtained from the mixed FeCr55C600 high carbon ferrochrome powders with a mean particle size of 4.65 μm and the Fe-0.5Mo water atomized pre-alloyed powders, sintered at 1 200℃ by sinter hardening process. The results indicate that the hardness and strength of the sintered alloys increase as the content of Cr-Fe alloy powder increasing. The microstructure of the sintered specimens is mainly composed of bainite. When adding ultrafine Cr-Fe alloy powder, leading to the Cr mass content of 1.7%, Fe-Cr-Mo PM steels have optimal properties, with tensile strength of 1 210 MPa and hardness of 30 HRC. Main microstructure of the alloy is a mixture of fine lower bainite and martensite, and mass ratio of the alloy element of Cr/C is about 1.54. 2015 Vol. 25 (02): 25-30 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 31 Influence of Al2O3 content on the properties of CNTs reinforced copper matrix composites CUI Zhao-wen, JIANG Li-kun, LIU Jian-jin, JIA Cheng-chang DOI: 10.13228/j.boyuan.issn1006-6543.20150005 By employing the combination of mechanical alloying (MA), magnetic stirring process (MS) and spark plasma sintering (SPS) process, the influence of Al2O3 content on the properties of carbon nanotubes (CNTs) reinforced copper matrix composites was studied. Results show that wear rate of the composite is reduced by 70.9%-85.7% and Vickers hardness is increased by 11.6%-24.5% compared with pure copper. The copper matrix composite has the best comprehensive properties when adding 1.0% CNTs and 1.6%Al2O3 (mass percent), showing the relative density of 97.5%, Vickers hardness of 75.2 HV, thermal conductivity of 272.45 W/(m·K), and electrical conductivity of 4.39×107 Ω-1·m-1. 2015 Vol. 25 (02): 31-34 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 35 Effect of torsion radius on the microstructure and hardness of SiCp/Al composite produced by high pressure torsion LIN Li-jing, WANG Cheng-guo, Li Ping, QIAO Shuo DOI: 10.13228/j.boyuan.issn1006-6543.20130121 SiCp/Al composites have a widespread use in the field of aerospace, automobile and so on, because of their good wear resistance, high specific strength and low coefficient of thermal expansion. High pressure torsion (HPT) was used to prepare SiCp/Al composites. The influence of torsion radius on the microstructure and hardness of the composite was investigated. The results show that the shear strengthening and equivalent strain increase, the particle agglomeration decreases, the distribution of SiC is more uniform and the micro-hardness of the composite increases with the increasing of torsion radius. 2015 Vol. 25 (02): 35-38 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 39 Research on microstructure of alumina/metal coating prepared by melting-casting XUE Xiao-feng, WANG Ze-hua, ZHOU Ze-hua, SHAO Jia DOI: 10.13228/j.boyuan.issn1006-6543.20140061 A sort of alumina/metal coating characterized by a bi-layered structure of Fe2O3+Cr2O3+Al plus NiO+Al layers, was successfully prepared on steel substrate by melting-casting technique. The microstructure, bonding status of the interface between the coating and the substrate, and the element distribution of the coating were studied. Results indicate that the coating is composed of α-Al2O3, Fe-Ni, Cr, AlNi3 and Fe-Cr. There is an excellent bonding between the coating and the substrate, and no hole or gap is found in the composite. Moreover, there is obvious element diffusion in the interface. The coating is composed of equiaxed grain, columnar grain, dendrites and lath phase. The elements present a uniform distribution in the interface but an obvious segregation in the middle of the coating. The segregation degree of metal elements is strengthened when extending the holding time. 2015 Vol. 25 (02): 39-45 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 46 Influence of pore density and porosity on heat transfer performance of copper foam LIU Han-qiang, ZHAO Peng, PU Yu-ping, SHEN Wei, ZHU Li-ran DOI: 10.13228/j.boyuan.issn1006-6543.20140076 Copper foams with nine different cell structural parameters were prepared by ultrasonic assisted electrodeposition process. The viscosity coefficient [K1], inertia coefficient [K2] and nusselt number [Nu] of copper foams were tested using water as working fluid in laminar -turbulent transition region (0.4～1.3 m/s). The influence of pore density and porosity of copper foams on flow, convective heat transfer and overall performance was discussed. Results show that [K1] and [K2] decrease by about 80% and 50%, and the [Nu] increases by about 100% when pore density increases from 10 ppi to 45 ppi at the same porosity, while [K1] and [K2] decrease by about 30% and 20%, and[Nu]increases by about 50% when porosity decreases from 96% to 90% at the same pore density. From the view point of overall performance, copper foam with pore density of 10 ppi, 96% porosity is a clear optimum. 2015 Vol. 25 (02): 46-51 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 52 Research progress on mechanical alloying preparation of nanocrystalline supersaturated solid solution in Fe-Cu immiscible system WU Zhi-fang, , ZHOU Fan, DOI: 10.13228/j.boyuan.issn1006-6543.20140050 Nanocrystalline supersaturated solid solution can be obtained by mechanical alloying in Fe-Cu immiscible system, which shows the unique properties compared with micro-scale structure. The progress in mechanical alloying of nanocrystalline supersaturated solid solution in Fe-Cu immiscible system was overviewed, with focus on the formation mechanism of nanocrystalline supersaturated solid solution, as well as mechanical and physical properties. 2015 Vol. 25 (02): 52-56 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 57 Research status of preparation and properties of BN-AlN composite ceramics LIU Huan, ZHANG Ning, ZHANG Tian-wen, KAN Hong-min, WANG Xiao-yang, LONG Hai-bo DOI: 10.13228/j.boyuan.issn1006-6543.20140048 Several preparation methods of BN-AlN composite ceramics were introduced, and the research status on the performance of BN-AlN composite ceramics was discussed. Then, the future development trend of BN-AlN composite ceramics was previewed. 2015 Vol. 25 (02): 57-62 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 63 A review of preparation techniques for ceramic particles reinforced iron matrix composites ZHANG Fan, WANG Li-ge, WANG En-ze, DU Jun-wu, LIU Kai-xiang DOI: 10.13228/j.boyuan.issn1006-6543.20140062 The physical and mechanical properties of ceramic reinforced particles were introduced, and the advantages, disadvantages and application status of some typical preparation techniques for ceramic particles reinforced iron matrix composites were reviewed with emphasis. As for the complex influencing factors for ceramic particles reinforced iron matrix composites, it is pointed out that the combination of existing preparation techniques and computer simulation is an important development direction in the future for the preparation of iron matrix composites. 2015 Vol. 25 (02): 63-69 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 70 Development of internally added lubricant for high-density compaction KYOUSHI Adachi, YUUKOU Mizuno, ZENG Rui DOI: 10.13228/j.boyuan.issn1006-6543.20140056 Now widely used internal lubricant, such as zinc stearate and EBS wax (N,N，-ethylenebis[stearamide]),are suitable for the stable production of PM parts with green density of 6.8-7.1 g/cm3. However, these lubricants are often lack of lubrication in the?production of parts with green density higher than 7.2 g/cm3, leading to abnormal wear and decreased service life of the mold, and increased defective rate. Basic performance of new developed wax lubricant (Adeka new developed wax lubricannt) was summarized.The results show that the new lubricant can be used in the stable and continuous production of high density parts with green density higher than 7.2 g/cm3. 2015 Vol. 25 (02): 70-73 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )

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