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Quick Search     Adv Search   2017 Vol. 27, No. 05 Published: 2017-10-10   1 Discussion on the properties of raw and auxiliary materials for iron-based sintered parts ZONG Hua-hui DOI: 10.13228/j.boyuan.issn1006-6543.20170125 The mechanical properties of sintered parts are mainly determined by the density of parts， the composition of materials， the properties of materials and the preparation process of materials. The comprehensive cost of the part can be reduced by optimizing the material composition and preparation process. The so-called new material and new technology， the first step in the manufacture of parts-raw materials， has shown its unique advantages. The various raw materials used in iron-based powder metallurgy parts were reviewed. The mechanical properties， processing properties， application status and development prospect were analyzed and discussed， and the effective way to optimize the performance of sintered parts was explored. 2017 Vol. 27 (05): 1-11 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 12 High velocity compaction behavior and sintered properties of Ti-29Nb-13Ta-4.6Zr alloy HE Jie，XIAO Zhi-yu，YANG Shuo，GUAN Hang-jian，ZHANG Wen DOI: 10.13228/j.boyuan.issn1006-6543.20160080 The Ti-29Nb-13Ta-4.6Zr powder was compacted with a self-developed high velocity compaction machine. The effect of impact energy on density as well as mechanical properties was investigated. The results reveal that the green density increases with increasing impact energy， the green density reaches a maximum of 5.63 g/cm3 （relative density of 94.1%） with impact energy of 1 805 J. The radial spring back of the samples increase with increasing impact energy. After sintered in vacuum at 1 250 ℃， the sintered density increases with the increase of impact energy while the volume of the sintered compacts expand and the sintered compacts obtain the maximum density of 5.53 g/cm3 （relative density of 92.5%）. After sintered for 2.0 h in vacuum， the sintered compacts obtain the highest tensile strength of 629.8 MPa and the highest hardness of 324.5 HV. 2017 Vol. 27 (05): 12-17 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 18 The effect of phenolic resin content on properties of automotive friction material LIU Bo-wei，，CHEN Jie，YANG Yang，CHEN Gang DOI: 10.13228/j.boyuan.issn1006-6543.20160070 Five kinds of composite brake with phenolic resin mass percent of 4%-12% was prepared through hot pressing method. The Link3000 inertia friction test bench， Link3900 NVH inertia friction test bench and Link3336 compression testing machine were used to test the friction performance， noise performance and compression performance of the brake. The effect of phenolic resin content on the friction and wear properties of the brake were discussed combined with the microstructure and mechanical properties analysis. Results show that with the increase of phenolic resin content， the average friction coefficient and high temperature friction coefficient decrease， leading to recession. At the same time， the braking noise， the noise probability and the noise intensity increase. When the mass percent of phenolic resin is 6%， the friction coefficient has the best stability， which is not easy to cause recession； and the noise probability is the minimum when the mass percent of phenolic resin is 4%-6%. 2017 Vol. 27 (05): 18-24 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 25 Influence of multi-walled carbon nanotubes on the mechanical properties of CuSn-Co matrix XU Qiang，LIU Yi-bo，，XU Liang，YANG Zhi-wei DOI: 10.13228/j.boyuan.issn1006-6543.20160071 Carbon nanotubes have superior mechanical properties and excellent physical properties （with elastic modulus of 1.0- 1.8 TPa， tensile strength of 150 GPa， density of up to 0.8 g/cm3， thermal expansion coefficient of almost zero）， which is the ideal reinforcement for composite materials. The effects of the multi-walled carbon nanotubes （MWCNT） addition， sintering temperature and hot pressing pressure on the mechanical properties of CuSn-Co matrix were investigated by orthogonal experimental design， and influence degree of the three factors on the mechanical properties of the matrix were analyzed by means of direct analysis and variance analysis respectively. The fracture morphology was also observed through scanning electron microscope. Experimental results show that the carbon nanotubes addition has the most significant influence on the hardness and bending strength of matrix， followed by hot pressing pressure， which has the second significant influence， and the sintering temperature has little effect. The final optimum scheme is as follows： the addition of MWCNT is 0.8% （mass percent）， the sintering temperature is 850 ℃， and the hot pressing pressure is 35 MPa. 2017 Vol. 27 (05): 25-31 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 32 Microstructure of Mg-5Gd-3Y-0.8Zr alloy and its corrosion resistance in NaCl solution YANG Jing-jing，TANG Xian-sheng，XIE Jiang-huai，MO Yu-mei DOI: 10.13228/j.boyuan.issn1006-6543.20160066 The microstructure and corrosion resistance of Mg-5Gd-3Y-0.8Zr alloys were studied systemically. The corrosion rate of the alloy in NaCl solution was measured by static weight loss test. The results show that the as cast alloy is mainly composed of α-Mg matrix and cubic β phase （Mg5Gd， Mg24Y5）. After aging treatment， the amount of β phase is obviously increased and mainly distributed in the grain boundary. The corrosion rate of magnesium alloy increases obviously after 12 h swamped in NaCl solution. After corrosion for 24 h in the 3.5%NaCl （mass percent） solution， the magnesium alloy has been seriously corroded， and the alloy surface is covered with corrosion pits and white corrosion products which have not fallen off. Magnesium alloy is prone to intergranular corrosion， and the cubic β phase particles can effectively prevent the surface corrosion extending to the alloy inside from the grain boundaries， thus improving the corrosion resistance of the magnesium alloy. 2017 Vol. 27 (05): 32-35 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 36 Study on the diversity of corrosion products of （Ce20Nd80）31FebalB1M magnet WU Ya-ping，ZHU Ming-gang，SHI Xiao-ning，SONG Li-wei，PAN Wei DOI: 10.13228/j.boyuan.issn1006-6543.20160057 The （Ce20Nd80）31FebalB1M magnets prepared by double main phase powder sintering process were corroded in highly accelerated stress test system. The corrosion morphology was observed and analyzed by EDS energy spectrum. Results show that the corrosion products are bobbles-like and ball-like after corroded for 24 h. The bobbles-like product is mainly rare earth oxide， which evolves into flocculent with the increase of etching time. While the ball-like product is mainly iron oxide， which partially falls off with the increase of etching time， and the remaining corroded particles are concluded on the substrate， preventing further corrosion to some extent. 2017 Vol. 27 (05): 36-40 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 41 Study on oxidation resistance of sintered nickel-based superalloy mesh porous materials GU Hu，YANG Jun-jun，WANG Hao，HUANG Zuo-qin，WANG Fan，ZHAO Jing-hui DOI: 10.13228/j.boyuan.issn1006-6543.20170022 The oxidation kinetics curve and oxidation rate of sintered nickel-based superalloy mesh porous materials with two different sizes and dense monofilament samples at 900 ℃ were tested through static weight gain method. The surface area of the porous small sample was tested through the 9410 automatic mercury porosimeter， and was also calculated through the permeability coefficient， and the oxidation rate of the porous small sample was corrected accordingly. The morphology and oxide composition of the porous samples were observed by SEM， EDS and XRD. The results show that the oxidation rate of the large and small porous samples is about 7 times that of monofilament sample after 100 h oxidation experiment. The oxidation rate of the modified small porous sample is much smaller than that before being corrected， which is also smaller than the oxidation rate of the monofilament sample. The surface oxide of the porous samples is spherical and distributed uniformly， and its composition is mainly NiCr2O4. 2017 Vol. 27 (05): 41-46 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 47 Microstructure and microwave dielectric properties of ZnO-B2O3 doped ceramics LIU Li-xin，ZHANG Yu-hua，LU Yin，LIU Xin-ning DOI: 10.13228/j.boyuan.issn1006-6543.20160060 The effects of ZnO-B2O3（ZB2） on the sintering behavior and microwave dielectric properties of （Ca0.254Li0.19Sm0.14）TiO3 ceramics were investigated. Results show that the relative densities of the specimens reach the maximum value when adding 3%ZB2 （mass percent）. The sintering temperature is lowered from 1 300 ℃ to 1 100 ℃ without degradation of the microwave dielectric properties. The （Ca0.254Li0.19Sm0.14 ）TiO3 ceramic with 3%ZB2 （mass percent） sintered at 1 100 ℃ for 3 h shows good microwave dielectric properties， which is[εr＝]108.2， [Qf＝]6 545 GHz， and[τf＝]6.5×10－6/℃， indicating that ZB2 is an effective sintering aid to improve the densification and microwave dielectric properties of （Ca0.254Li0.19Sm0.14）TiO3 ceramics. 2017 Vol. 27 (05): 47-52 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 53 Performance characteristics and research progress of metal powders for 3D printing GAO Chao-feng，YU Wei-yong，ZHU Quan-li，，XIAO Zhi-yu DOI: 10.13228/j.boyuan.issn1006-6543.20160062 Different from traditional manufacturing， 3D printing (additive manufacturing) is a new manufacturing technology with simplified manufacturing process， lower manufacturing costs and shorter development cycles. Nowadays， 3D printing technology is no more confined in laboratory， but now much toward to industrialization. But the limited variety， mass production and performance of the metal powder specifically used for 3D printing have became a constraint to the fast and healthy development of the industry. Metal powders for 3D printing need to meet the requirements of high purity， high sphericity and narrow particle size distribution. Major manufacturing technology for 3D printing metal powders includes atomization， plasma， rotation electrode process， plasma wire atomizing technologies. The effects of powder requirements， preparation methods and powder properties on the forming effect of 3D printing parts were introduced. The existing problems in the preparation of metal powders for 3D printing were also discussed. 2017 Vol. 27 (05): 53-58 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 59 The research progress of near net shaping hot isostatic pressing simulation QU Zong-hong，，LIU Jian-tao， DOI: 10.13228/j.boyuan.issn1006-6543.20160073 Near net shaping hot isostatic pressing （NNS-HIP） forming process has the advantage of high material utilization ratio and good uniformity of billet microstructure. It is an important forming process for complex shape parts made of nickel based PM superalloys and PM titanium alloys etc. The characteristics and production process of NNS-HIP， development and applications at home and abroad were introduced， and the microscopic and macroscopic powder densification models were also presented. By comparing and analyzing the numerical simulation and experimental results of hot isostatic pressing of different models， the advantages and disadvantages of different models were summarized， and the factors affecting the accuracy of numerical simulation were analyzed. 2017 Vol. 27 (05): 59-67 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 68 Effect of reasonable feeding control on properties of free cutting steel powder containing sulfur LIU Zhao-wa，ZHANG De-jin，QIU Peng DOI: 10.13228/j.boyuan.issn1006-6543.20170044 The phenomena of high total oxygen content and low compressibility often appear in the free cutting steel powder containing sulfur. It can be improved by adjusting the material thickness and changing the feeding way. Results show that the total oxygen content is reduced and the compressibility is increased effectively when the powder thickness is less than 25 mm with the original process. The looseness of the powder is improved by changing the feeding method. The 30 mm material thickness can meet the performance standard under the same process condition， and there is room for further improvement. 2017 Vol. 27 (05): 68-70 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 71 Experimental study on ultrasonic aided grinding surface quality of carbon fiber composites XIAO Chun-fang，HAN Bing DOI: 10.13228/j.boyuan.issn1006-6543.20170101 The ultrasonic aided grinding surface quality of carbon fiber composite was studied. The surface quality evaluation method of composite materials was analyzed. The grinding experiments were carried out under different processing parameters， and the removal mechanism and debris morphology of ultrasonic assisted grinding were studied. The results show that the surface roughness of the workpiece processed by ultrasonic aided grinding is 10%-30% less than that processed by ordinary grinding， and the machining surface formed by ultrasonic aided grinding is more smooth， the consistency is better， and the good surface quality is easier to form. 2017 Vol. 27 (05): 71-74 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )

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