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Quick Search     Adv Search   2019 Vol. 29, No. 04 Published: 2019-08-10   1 Recent PM materials and technologies in automotive industry Hot! XIONG Xiang，YANG Bao-zhen，LIU Yong，LIU Ru-tie DOI: 10.13228/j.boyuan.issn1006-6543.20190118 The characteristics of powder metallurgy technology and its advantages in auto parts manufacturing were introduced. The development and applications of new iron-base materials and aluminum alloy materials for powder metallurgy were reviewed. Specially, the characteristics of injection molding and additive manufacturing technology were summarized, and their applications in automotive parts were introduced. Prospects for the application of these new materials and new technologies were presented. 2019 Vol. 29 (04): 1-7 [Abstract] ( 5 ) HTML (1 KB)  PDF (1613 KB)  ( 7 ) 8 Study on forming mechanism of defects in metal injection molding of 42CrMo4 high strength structural parts Hot! CHEN Zhi-chao, ZHANG Peng, PENG Shi-min DOI: 10.13228/j.boyuan.issn1006-6543.20180010 The formation mechanism of defects in the metal injection molding (MIM) process of ultra-high strength alloy 42CrMo4 steel was studied and discussed. The results show that the microstructure of the metal injection 42CrMo4 alloy contains a large number of pores and cracks, which are caused by bonding defects after supercooling due to the intersection of viscosity bodies during the injection process. During the degreasing process, the viscosity bodies cannot be completely fused, and the space among the powders form the boundary between the viscosity bodies. Under the condition of low sintering driving force, the defects are enlarged in the subsequent cooling shrinkage process to form internal holes and cracks. 2019 Vol. 29 (04): 8-11 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 12 Study on the influence of process conditions on energy consumption in electrolytic copper powder process Hot! WANG Hong-dan, XIA Wen-tang, REN Bing-zhi, SUN Ya-feng, DENG You-ming DOI: 10.13228/j.boyuan.issn1006-6543.20170154 Electrolytic process has the highest energy consumption in copper powder production, and process conditions have an important impact on electrolytic energy consumption, which needs in-depth research and optimization. Copper powder was prepared by electrolysis. The effects of interelectrode gap, Cu 2＋ concentration, sulfuric acid concentration, electrolyte temperature, current density and scraping period on cell voltage, current efficiency and DC power consumption in electrolytic copper powder process were studied. The results show that increasing Cu 2＋concentration, electrolyte temperature and powder scraping period are conducive to reducing cell voltage and improving current efficiency, thus reducing DC power consumption. The cell voltage, current efficiency and DC power consumption of electrolytic copper powder increase when the interelectrode gap is increased. However, when the concentration of sulfuric acid is increased, the cell voltage, current efficiency and DC power consumption of electrolytic copper powder are reduced. When the current density is increased, the cell voltage of electrolytic copper powder is significantly increased and the current efficiency is slightly decreased, resulting in a significant increase in DC power consumption. The optimum process parameters of electrolytic copper powder are: interelectrode gap 20-40 mm, Cu 2＋ concentration 10-15 g/L, sulfuric acid concentration 150 g/L, electrolyte temperature 40-50 ℃, current density 1 500 A/m2, and powder scraping period 45 min. 2019 Vol. 29 (04): 12-16 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 17 Preparation of high performance spherical titanium alloy powder for 3D printing by inert gas induction melting Hot! FAN Ya-zhuo, XIE Bo, MIAO Qing-dong, ZHAO San-chao DOI: 10.13228/j.boyuan.issn1006-6543.20180016 Spherical titanium alloy powder for high performance ultra-fine low oxygen 3D printing was prepared by electrode induction melting gas atomization. The effect of atomization angle on primary powder formation rate and the relationship between powder particle size and primary oxygen enrichment rate were studied. The results show that atomization angles have a great influence on the primary powder forming rate, too large or too small atomization angle is not conducive to the improvement of the primary powder forming rate. Only when the atomization angle is about 33 degrees, the primary powder forming rate is the best (about 80%), and the titanium alloy powder obtained under this condition has good sphericity and less associated phases. When the particle size of spherical titanium alloy powder is 60-150 μm, the primary oxygen enrichment gradually decreases with the increase of particle size. The primary oxygen enrichment increases rapidly when the particle size of the powder is less than 60 μm, while the primary oxygen increase hardly changes when the particle size of the powder is larger than 150 μm. 2019 Vol. 29 (04): 17-20 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 21 Research on micro-porous surface forming process based on selective laser melting Hot! LI Pei, QIAN Bo, ZHANG Chi, ZHANG Jian-rui, WEI Qing-song DOI: 10.13228/j.boyuan.issn1006-6543.20180008 Microporous surfaces can enhance boiling heat transfer and have broad industrial application prospects. Selective laser melting (SLM) is a new manufacturing method for microporous surfaces. The effects of scanning spacing and laser power on 316L stainless steel powder forming micro-porous surface during SLM process were mainly studied. The results show that the pores on the surface of the micro-porous formed by scanning spacing of 0.3-0.5 mm are regular through holes, and a large number of powder bonds exist on the inner wall of the holes, which can form a large number of potential gasification cores. Using 180-240 W laser power and 0.2-0.5 mm scanning spacing, a micro-porous surface with hydraulic diameter of 78.9-410.5 μm and porosity of 11.6%-50.2% is obtained. The boiling heat transfer experiment was carried out with deionized water. The initial boiling temperature of the micro-porous surface formed by 240 W laser power and 0.5 mm scanning spacing is 104 ℃, and the critical heat flux is 150 W/cm2, which has obvious boiling heat transfer enhancement effect. 2019 Vol. 29 (04): 21-28 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 29 Effect of Mo content on mechanical and tribological properties of Ni-8Cr-6Al alloy prepared by powder metallurgy method Hot! QU Xiao-li, WANG Tao DOI: 10.13228/j.boyuan.issn1006-6543.20180013 Ni-8Cr-6Al alloy with different Mo content was prepared by powder metallurgy method. The effect of Mo content on its mechanical and tribological properties was studied by SEM and XRD. The results show that Al2O3 is formed in Ni-8Cr-6Al-xMo alloy samples, and the microstructure is uniform and compact. With the increase of Mo content, the density, hardness and room temperature compression properties of the alloy increase. Ni-8Cr-6Al-4Mo alloy has excellent mechanical properties in wide temperature range and good tribological properties at high temperature. When the Mo content is too high, Mo2C phase is formed in the high temperature (400 ℃ and above) friction process, which will produce pinning effect, making the lubricating phases such as MoO2 and NiO generated in the friction stage unable to form continuous films, thus reducing the friction performance of the alloy. 2019 Vol. 29 (04): 29-32 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 33 Friction and wear performance analysis of sintered RGO/Cu-Ag composites for brake shoes Hot! LI Yuan-jun DOI: 10.13228/j.boyuan.issn1006-6543.20190038 The surface of graphene oxide (RGO) was loaded with nano-Cu particles by electroless plating, and then mixed with Cu-Ag matrix to prepare RGO/Cu-Ag composite materials. SEM and XRD tests were carried out, and the wear resistance of the samples was characterized by a friction tester. The results show that when the mass percent of RGO is 4%, the surface of the composite is in a state of combination of particles and flakes. With the increase of RGO content, the hardness and elastic modulus of the composite increase first and then decrease. When the mass percent of RGO is 4%, the hardness and elastic modulus of the composite are the largest, which are 64.82 HV and 104.26 GPa, respectively. At this time, the sample is worn into a strip-shaped furrow shape with regular arrangement, and the original scabbing rough area disappears. With the increase of RGO content, the friction coefficient of the sample first decreases and then increases. When the mass percent of RGO is 4%, the friction coefficient of the sample reaches the lowest value of 0.28, while the surface roughness decreases to 1.68 μm. 2019 Vol. 29 (04): 33-37 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 38 Study on properties of SiC particle reinforced aluminum matrix composites for vehicle braking Hot! QIU Cui-rong DOI: 10.13228/j.boyuan.issn1006-6543.20180011 The 30%SiCp/6082Al (volume percent) composite for vehicle braking was prepared by powder metallurgy technology. The effect of sintering temperature on the microstructure and properties of the composite was studied. The results show that uniform SiC particles are distributed in the matrix of 30%SiCp/6082Al composite material, and the Si content increases with the increase of sintering temperature. After sintering, various reaction products such as Si, Mg2Si, SiO2, etc. are formed in the composite material. With the increase of sintering temperature, the density of the composite material increases firstly and then decreases. After sintering at 700 ℃, the bending strength of the composite material reaches the highest value of 364 MPa. There are many tiny pores with different shapes in the cross-sectional area of the composites sintered at 650 ℃, and most SiC particles show cleavage fracture characteristics. As the sintering temperature increases, the number of pores decreases and gradually changes into a more uniform spherical structure, and nearly all SiC particles show cleavage fracture characteristics. 2019 Vol. 29 (04): 38-41 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 42 Microstructure and mechanical properties of carbon fiber reinforced Al-Cu matrix composites for vehicles Hot! WEI Yu-tang, CUI Su-hua DOI: 10.13228/j.boyuan.issn1006-6543.20190029 The carbon fiber reinforced Al-Cu matrix composite coated with Cu electroplating solution was prepared by vacuum pressure infiltration method, and the mechanical properties of the samples were tested and the microstructure was observed. The results show that the surface of carbon fiber is plated with Cu to form an interface layer with compact structure and thickness of about 1 μm. A good bonding state is formed between carbon fiber and Al-Cu matrix, but no carbon fiber bundles separated from Al-Cu matrix is found. The carbon fiber has been fully permeated by the Al-Cu liquid, and no voids are found in the matrix. In addition to C and Al, Al2Cu intermetallic compound also exists in the composite material compared with the Al-Cu substrate. Compared with Al-Cu substrate, the tensile strength of CF/Al-Cu matrix composite is significantly increased. Many microcracks are formed in the carbon fiber bundle at the fracture stage, and stepped fractures are formed at this time, and the fracture site also has a flat structure. 2019 Vol. 29 (04): 42-46 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 47 Hydrothermal preparation of MnO2/NiCo2O4 nanocomposite coating on stainless steel and analysis of its structure and hydrogenation properties Hot! WU Chang-you, LIU Jun-chao, HE Wen DOI: 10.13228/j.boyuan.issn1006-6543.20180122 MnO2, NiCo2O4 and MnO2/NiCo2O4 nano-films were prepared on stainless steel substrates by hydrothermal method. SEM, XRD, TEM analysis were carried out, and their hydrogen evolution effects were characterized electrochemically. The results show that MnO2 nano-materials form a uniform distribution on the surface of stainless steel and have a petal-shaped stacked structure. NiCo2O4 nano-materials are in vertical form, showing obvious alignment trend. In addition to the three characteristic diffraction peaks corresponding to stainless steel, the XRD pattern of MnO2/NiCo2O4/316L also forms the diffraction peak corresponding to NiCo2O4, and the characteristic peak of MnO2(220) crystal plane appears to shift to a low angle. The polarization curve test shows that MnO2/NiCo2O4 nanomaterials have excellent hydrogen evolution performance, and with the increase of overpotential, the current density also increases significantly, with a faster hydrogen evolution reaction speed, indicating that the hydrogen evolution performance is improved by synergistic effect between NiCo2O4 and MnO2. 2019 Vol. 29 (04): 47-50 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 51 Tribological properties of nano-particles reinforced copper-based spray friction plate Hot! ZHANG Guo-hong, XU Cheng-fa, FENG Xiu-ming, XU Yao, DU Jian-hua DOI: 10.13228/j.boyuan.issn1006-6543.20180129 The effects of nano-materials, ball milling and graphite morphology on tribological properties of copper-based spray friction materials were studied by adjusting the composition ratio, adding nano-materials, adopting ball milling process and changing graphite morphology. The results show that adding Ni/n-SiO2 and ball-milled Cu/natural graphite, ball-milled Cu/n-SiO2 and ball-milled Cu/natural graphite can improve the comprehensive properties of copper-based spray friction plates. Ball-milled Cu/nano graphite+ball milled Cu/natural graphite can improve the wear resistance and heat resistance of copper-based spray friction materials, but can significantly reduce the friction coefficient of friction materials. The preparation of Cu-graphite composite particles by ball milling method can increase the graphite content in the matrix of copper-based spray friction materials, thus significantly improve the heat resistance of friction materials. 2019 Vol. 29 (04): 51-58 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 59 Preparation and tribological properties of Niss/Ni3Si eutectic composite Hot! YUAN Ya, HAN Ming-gang, CHEN Hui DOI: 10.13228/j.boyuan.issn1006-6543.20180020 Niss/Ni3Si eutectic composites were prepared by mechanical alloying and hot pressing method, and its microstructure and tribological properties were studied. The results show that the composites are mainly composed of Niss, Ni3Si and Ni31Si12. The composites have a good combination of strength and toughness. The sintered density, hardness, bending strength and fracture toughness of the Niss/Ni3Si composites are 98.5%, 668 HV, 741 MPa and 8.92 MPa . m1/2, respectively. The composite has a low friction coefficient and wear rate. With the increase of the load, the friction coefficient of composite decreases and the wear rate rises slowly. The wear mechanism is changed from adhesive wear under low load to abrasive wear under high load. At the same time, there is an oxidation wear during the wear process. 2019 Vol. 29 (04): 59-62 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 63 Friction properties of Fe-Cu-C oil-bearing Hot! WEN Xin-rong, QIN Jun-hua, WEI Chang-xing, FAN Min-zhong, SHEN Xiao-ping DOI: 10.13228/j.boyuan.issn1006-6543.20180023 The friction performance of Fe-Cu-C oil-bearing was studied by changing the composition ratio of Cu and graphite, and the bearing formula under certain working conditions was obtained. MoS2 was added as solid lubricant to further optimize the formula and improve the friction and wear performance of the bearing. The results show that the limiting PV value of oil-bearing with Fe-22.0Cu-1.5C component is the highest, and the friction coefficient of oil-bearing with Fe-16.0Cu-1.5C component is the lowest. When 2.0％MoS2 is added to Fe-22.0Cu-1.5C oil bearing, the friction performance of the oil bearing can be effectively improved. 2019 Vol. 29 (04): 63-68 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 69 Effect of B addition on SPS properties of atomized Ti-48Al-2Cr-2Nb alloy powder Hot! ZHANG Jian-lin DOI: 10.13228/j.boyuan.issn1006-6543.20180025 The effects of various B additions on the spark plasma sintering (SPS) properties of atomized Ti-48Al-2Cr-2Nb alloy powder were studied. The results show that the rapid densification temperature of Ti-48Al-2Cr-2Nb alloy is obviously reduced by adding B element. After sintering, the alloy added with B element has obvious densification, and the dendritic structure are all disappeared. At the same time, a clearer phase interface is formed, and the grains are obviously refined. The alloy added with 0.2%B reaches the highest mechanical properties after sintering, and the tensile strength, yield strength and elongation are 524 MPa, 488 MPa and 9.62%, respectively. 2019 Vol. 29 (04): 69-72 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 73 Effect of WC content on properties of Cu-based powder metallurgy friction materials Hot! LIU Jian-xiu, SUN Lu-lu, LI Yu-wen DOI: 10.13228/j.boyuan.issn1006-6543.20180003 Copper-based powder metallurgy friction materials containing WC were prepared by powder metallurgy method. The effect of WC content on microstructure and properties of copper-based powder metallurgy friction materials was studied. The results show that when the mass percent of WC is less than 4%, the porosity of copper-based friction material decreases with the increase of WC content, and when the mass percent of WC exceeds 4%, the porosity obviously increases with the increase of WC content. With the increase of WC content, the density of copper-based friction material basically remains unchanged. The hardness of friction material increases with the increase of WC content. The addition of WC improves the friction performance of the friction material and increases its wear resistance with the increase of WC content. When the mass percent of WC is 4%, the copper-based powder metallurgy friction material has the best friction performance. 2019 Vol. 29 (04): 73-77 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 78 Characteristic analysis of Sb-doped ZnO nano-wire prepared by thermo-chemical vapor deposition Hot! DUAN Chun-Yan， HAN Hui-Li DOI: 10.13228/j.boyuan.issn1006-6543.20180172 In this paper, Sb-doped ZnO nanowires were grown on Si (100) substrates by thermochemical vapor deposition. The structure and photoelectric properties of the samples were analyzed. XRD analysis shows that the nanowires are hexagonal wurtzite structure, and their crystallinity decreases with the increase of Sb doping amount. TEM observation shows that the growth direction of nanowires is [0001] crystal plane. XPS analysis shows that Sb3+ successfully doped into the crystal structure of ZnO. After Sb doping, the ultraviolet luminescence position of nanowires shifted from 382 nm to 389 nm, and the green luminescence intensity decreased at 2019 Vol. 29 (04): 78-81 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 82 Research progress in preparation of silicon nitride ceramic powder Hot! XU Chen-hui, ZHANG Ning, ZHAO Jie-nan, ZHOU Bin-bin, KAN Hong-min, WANG Xiao-yang DOI: 10.13228/j.boyuan.issn1006-6543.20180050 Silicon nitride ceramic is a kind of high-temperature structural ceramic with excellent performance and broad development prospects. High-purity and ultra-fine silicon nitride powder is the key and foundation for preparing excellent silicon nitride ceramic. The preparation methods of silicon nitride ceramic powder were mainly introduced, the advantages and disadvantages of various preparation methods were analyzed, and the current research situation was pointed out. Finally, the prospect of the preparation of silicon nitride powder was looked forward. 2019 Vol. 29 (04): 82-86 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 87 Effect of raw material preparation methods on properties of Ni moulded parts by selective laser melting Hot! TANG Zi-lei DOI: 10.13228/j.boyuan.issn1006-6543.20180179 Ni powder prepared by spray drying and gas atomization were used as printing materials, respectively. Ni melting moulded parts were prepared by selective laser melting (SLM) technology, and their transverse and longitudinal microstructure characteristics were observed. The results show that the two kinds of Ni powder particles prepared by spray drying and gas atomization both have good sphericity. Most of the powder particles are smaller than 50 μm, and the sphericity is above 0.8. Both of them have very pure phase structure with Ni phase only. A melt channel with a width of about 85 μm is formed in the moulded part prepared by spray drying Ni powder, while a melt channel with a width of 75 μm is formed in the moulded part prepared by gas atomized Ni powder. There are many defects and some irregular holes in moulded parts prepared by gas atomized Ni powder. There are many oval molten pools in overlapping state on the longitudinal surface of the sample, and the sample prepared by spray drying Ni powder has a deeper molten pool depth than that prepared by gas atomized Ni powder sample. 2019 Vol. 29 (04): 87-91 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )

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