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Quick Search     Adv Search   2017 Vol. 27, No. 04 Published: 2017-08-10   1 Characteristics，status analysis and development trend of metal powders for diamond tools LIU Yi-bo，XU Qiang，XU Liang DOI: 10.13228/j.boyuan.issn1006-6543.20170070 The characteristics of metal powders for diamond tools were introduced，mainly including the wear resistance and matching of matrix，the holding force for diamond，the pressing，sintering and security performance. The types，manufacturers，preparation methods，morphology and particle size of the powder and the pre-alloy powder at home and abroad were listed，and the chemical composition of the powder，the sintering temperature，the hardness，the use and so on were also provided. Finally，the development trend of metal powders was introduced with focus on the emergence problems at home，which was for reference to raw material manufacturers and users. 2017 Vol. 27 (04): 1-6 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 7 Study on the properties of spherical cast tungsten carbide powders prepared by different methods WANG Lei，LIU Xin，XIE Huan-wen，ZOU Li-ming，CAI Yi-xiang DOI: 10.13228/j.boyuan.issn1006-6543.20160058 The spherical cast tungsten carbide powder is a kind of new potential wear-resistance ceramic material. The chemical composition，morphology，microstructure，phase composition，micro-hardness，flowability，loose density and other characteristics of spherical cast tungsten carbide powders prepared by different methods were investigated. The results indicate that，compared with plasma re-melting spheroidizing and induction re-melting spheroidizing，the deviation value between the total carbon content and the theoretical carbon content of spherical cast tungsten carbides fabricated by plasma rotation electrode atomization method is the smallest，and the content of free carbon and impurities are the lowest. Furthermore，the corresponding powder particles fabricated by plasma rotation electrode atomization method are denser，the eutectic microstructure is finer and microhardness is higher than those fabricated by other methods. Spherical cast tungsten carbides fabricated by induction re-melting spheroidizing have the best flowability and the highest loose density. 2017 Vol. 27 (04): 7-11 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 12 Preparation and formation mechanism of hollow ammonium metatungstate spheres by spray drying method ZHANG Li-na，SU Qi，YANG Gao-ling，SHI An-hong，LIU Bai-xiong DOI: 10.13228/j.boyuan.issn1006-6543.20160128 Nano-WO3 based materials have many properties，such as photodegradation，water splitting，electrochromism，thermochromism and photochromism，etc. Therefore，nanostructured WO3 based materials are potentially used in the fields of photocatalysis，new energy resources preparation，smart windows，sensors and flat-panel display. Hollow ammonium metatungstate spheres were synthesized by spray drying method，and the preparation process and formation mechanism of the hollow structure were analyzed. Results show that the average diameter of the hollow ammonium metatungstate ball is 1.03 μm，and the wall thickness is about 100 nm. The preparation process is divided into 3 stages： atomization，shell formation during flash evaporation and hollow structure formation. Since the initial temperature in hot air drying tower is 130 ℃，far higher than the boiling point of water，leading to rapid evaporation of droplet surface water. The fast evaporation speed leads to the droplet surface crystallization and the shell formation，thus the hollow structure forms. 2017 Vol. 27 (04): 12-16 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 17 Preparation and characterization of Co3O4 by wet precipitation-thermal decomposition with oxalate LI Hui-ying，WANG Wen-xiang，LIU Ying，YAN Ying-yan，LIU Zhi-hong DOI: 10.13228/j.boyuan.issn1006-6543.20160110 The cobalt oxide precursor was prepared by wet precipitation method with cobalt chloride as cobalt source，ammonium oxalate as precipitating agent，and Tween-80 as surfactant. The Co3O4 powder was obtained by thermal decomposition method. The morphology，crystal structure and thermal decomposition of precursor particles and Co3O4 powder were characterized by scanning electron microscope，X-ray diffractometer and thermal analyzer. Results show that the precursor of cobalt oxide prepared with oxalate as precipitant is CoC2O4·2H2O. Relatively pure Co3O4 powder can be obtained when the precursor is calcined at 600 ℃ for 4 h. The Co3O4 powder basically maintains the original shape of precursor，which are still needle (rod) shape and the edge of the particles become smooth. 2017 Vol. 27 (04): 17-21 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 22 Preparation of magnetic abrasive by dual-nozzle atomizing water-cooling method and its grinding performance ZHANG Gui-guan，ZHAO Yu-gang，GAO Yue-wu DOI: 10.13228/j.boyuan.issn1006-6543.20160149 Spherical and near-spherical magnetic abrasives were prepared by gas-solid two-phase flow atomization with double nozzle water-cooling. The surface morphology of magnetic abrasive was observed using field emission scanning electron microscope (FESEM)，and the quantitative and qualitative analysis of surface elements were analyzed through energy diffraction spectrometer (EDS). The grinding performance of the prepared magnetic abrasives was analyzed by XK7136C CNC milling machine planar magnetic grinding device. The results show that the spherical magnetic abrasive prepared by atomizing and water cooling of gas-solid two-phase flow has good polishing and finishing effect，and the magnetic abrasive still has good precision finishing ability after using for 40 min. 2017 Vol. 27 (04): 22-25 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 26 Preparation of nano-sized potassium metavanadate-thallium nitrate composite powder and its photocatalytic degradation property to Sudan red II SUN Shu-xiang，HUANG Xiao-ying，WU Ben-lai DOI: 10.13228/j.boyuan.issn1006-6543.20170063 The nano-sized potassium metavanadate-thallium nitrate composite powders were synthesized using hydrothermal method with thallium nitrate，potassium metavanadate，sodium sulfite and manganese ioxide as raw materials.The degradation capacity of the powder to Sudan red II was investigated after activation. The nano-sized composite powders were also characterized by SEM，XRD and XPS. The results show that，when 2.5% （mass percent） potassium metavanadate is doped with thallium nitrate，the composite powder has the most effective catalytic activity. It can degrade 200 mL Sudan red II solution with concentration of 1×10－3 mol/L effectively by using 25 mg nano-sized potassium metavanadate-thallium nitrate composite powders. 2017 Vol. 27 (04): 26-30 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 31 Simulation on filling density of titanium powder in vibration forming based on EDEM LIANG Zeng-hua，LIU Qiu-zu，MA Lin，SHANG Zhu-xian DOI: 10.13228/j.boyuan.issn1006-6543.20160074 Mechanical vibration can effectively reduce the porosity and improve the packing density of titanium powder particles. Based on establishing the dynamic equation of particles contact process by discrete element method，numerical simulation of the titanium powder particle filling process was conducted using EDEM discrete element software，and the vibration state of titanium powder in different directions was analyzed. Results show that the filling density of titanium powder with single direction vibration is higher than that with two directions or three directions. The steady-state average packing density of[x]direction is 1.04 times and 1.06 times of[xy]and[xyz]directions，respectively. With the increase of vibration time，the filling density increases firstly and then turns stable. The optimum vibration time is 20 s. The simulation has certain reference significance for the actual production of titanium powder. 2017 Vol. 27 (04): 31-34 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 35 Tribological properties analysis of copper-based bimetallic bearing material containing FeS XUE Lu，YIN Yan-guo，ZHANG Guo-tao，LI Ji-ning DOI: 10.13228/j.boyuan.issn1006-6543.20160052 The Cu-based bimetallic bearing material containing FeS was prepared by the traditional powder metallurgy method and compared with the Cu-based bimetallic bearing material without FeS. The friction and wear properties of the Cu-based bimetallic bearing material were tested on HDM-20 end machine，and the wear marks were observed through the optical microscope. The results show that under the condition of sufficient lubrication，the antifriction properties and bearing capacity of copper-based bearing material with FeS are better than those without FeS. Under the condition of dry friction，the antifriction property of the copper-based bearing material with FeS is better than that without FeS. 2017 Vol. 27 (04): 35-39 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 40 Research on microstructure and arc erosion resistance of W-25Cu composite materials for photovoltaic power switch ZHANG Jing-jie，LIU Xing-ya DOI: 10.13228/j.boyuan.issn1006-6543.20170050 The W-25Cu composite material with fine grain was obtained by the hydrothermal co-reduction method. The microstructure and the morphology variation after arc erosion were also analyzed. Results show that the microstructure of W-25Cu composite material has an obvious densification characteristic. The fine W phase particles are surrounded by Cu phase totally. The distribution of Cu and W phases is very uniform，and the grain size of W phase is 1-3 μm. The fracture zone shows an obvious dimple toughening characteristics. In the fracture stage，many curved fine tear edges and many dense small fracture dimples are formed. After the arc erosion，the surface phase is mainly composed of Cu and W phase，and the surface is smooth without obvious holes and cracks. During the fracture closure stage，the material transfer process is mainly characterized by arc transfer，melting bridge transfer and splash evaporation. 2017 Vol. 27 (04): 40-43 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 44 Experimental study on ultrasonic assisted grinding of carbon fiber composites XIAO Chun-fang，HAN Bing DOI: 10.13228/j.boyuan.issn1006-6543.20170031 Experimental study on ultrasonic assisted grinding technology of carbon fiber composites was carried out. Firstly，the single factor experiment of the relationship between the ultrasonic amplitude and the surface quality of the workpiece was carried out. Then the orthogonal experiments were carried out to analyze the influence of tool size，feeding rate，grinding depth and spindle speed on the surface quality of workpiece. Finally，the optimized machining parameters were tested and verified. The resin matrix carbon fiber composite material processed by the optimized process parameters has remarkably improved surface quality. 2017 Vol. 27 (04): 44-48 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 49 Current progress and prospect of numerical simulation in powder compaction YOU Meng-meng，PAN Shi-yan，，SHEN Xiao-ping，FAN Cang DOI: 10.13228/j.boyuan.issn1006-6543.20160054 Numerical simulation has become an effective tool in research and application of the powder compaction process. The mechanical modeling methods，the typical yield models and the material parameters （e.g.Young’s modulus，Poisson’s ratio and flow stress） used in the finite element simulation of powder compaction process were summarized. In addition，several softwares commonly used in this field，such as MSC.Marc，ABAQUS，DEFORM and ANSYS were compared in detail. Based on the current research situation，the future of simulation technique in powder metallurgy field was expected，and the primary development directions was pointed out，which were establishing more accurate mathematical models，enhancing 3D simulation and multi-fields coupling ability，applying software secondary development technology and improving numerical precision and practicality. 2017 Vol. 27 (04): 49-58 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 59 The research development on industrial combustible dust explosion YUAN Shuai，WANG Qing-hui，WANG Dan-feng DOI: 10.13228/j.boyuan.issn1006-6543.20160152 Research development on explosion of industrial combustible dust was reviewed comprehensively. Experimental and theoretical research achievements were summarized and analyzed. Firstly，the occurrence and development of dust explosion and the understanding of its mechanism were introduced，and the experimental research of dust explosion was summarized from the factors of characteristic parameters. Secondly，the application of numerical simulation and the development of mathematical model in dust explosion were described. Finally，the current protection measures and fire preventing of dust explosion were briefly introduced. The shortcomings for the present research were analyzed and future research trend was also put forward. Meanwhile，the research significance of dust explosion was pointed out. 2017 Vol. 27 (04): 59-65 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 66 Development of powder metallurgy CHEN Meng-ting，SHI Jian-jun，CHEN Guo-ping DOI: 10.13228/j.boyuan.issn1006-6543.20160123 With the rapid development of global industrialization，powder metallurgy technology has been widely applied into various fields. Powder metallurgy has advantages of high utilization rate of raw materials，low manufacturing cost and low material waste loss. At the same time，PM products have the advantages of high precision and stability. Powder metallurgy can be used to prepare materials and parts that are difficult to be prepared by conventional methods. Therefore，study of powder metallurgy is becoming more and more important. The production of powder metallurgy has been able to meet the basic needs of the national economic construction in China. More importantly，powder metallurgy science provides new materials for Chinese national defense construction and makes great contributions for military engineering construction. The powder metallurgy development history was described，the industry development situation in North America，Europe，Japan，China and some other countries were discussed，and development and application of new technology and new materials were described. According to the development of powder metallurgy industry and technology in China，some suggestions were also put forward. 2017 Vol. 27 (04): 66-72 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 73 Discussion on the design of the mould for the gear hub of powder metallurgy automobile synchronizer SUN Guo-xun DOI: 10.13228/j.boyuan.issn1006-6543.20170010 The use of powder metallurgy parts in automobile is more and more extensive. Because of the high requirements for the dimensional precision and the shape precision of the synchronizer gear hub，the forming and shaping of the blank is the most critical step in the production. One gear hub which has a disconnected sliding groove end，the outer tooth wheel disc is particularly thin，the spoke has different depth on the two sides，and the two ends of the hub are different in size. It need to reduce new deformation and is hard to control in shaping. By improving the die structure，the upper and lower two die presses structure were adopted，and the core rod was arranged on the upper central cylinder. The core rod was supported by the upper end surface when mould unloading，the upper end surface area was enlarged，and the tooth shape deformation was avoided. The utility model has the advantages of mass production and high practical value. 2017 Vol. 27 (04): 73-78 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )

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