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Quick Search     Adv Search   2021 Vol. 31, No. 01 Published: 2021-02-10   1 Synthesis，main properties and applications of new carbon quantum dots in new materials Hot! YI Jianhong，ZHAOWenmin，BAO Rui，FANG Dong，YOU Xin DOI: 10.13228/j.boyuan.issn1006-6543.20200235 In recent years，carbon quantum dots（CQDs）as a new type of carbon nanomaterials have attracted widespread attention. In addition to unique and excellent optical properties，CQDs also have good water solubility， biocompatibility，low toxicity，and low cost. Since the discovery of CQDs，people have develop a variety of synthesis methods，such as template method，microwave method，hydrothermal method，magnetron thermal method，etc.，and because of its excellent properties，they have been widely used in biology，environment，energy， and related material fields. The synthesis route，main properties of CQDs，and its applications and prospects in energy，electronics and biological materials were clarified. 2021 Vol. 31 (01): 1-8 [Abstract] ( 2 ) HTML (1 KB)  PDF (1720 KB)  ( 5 ) 9 In situ synthesis of nanoscale NbC-Co composite powder and its application in sintered cemented carbides Hot! WANG Haibin，ZHANWangbin，LIU Xuemei，LIU Chao， HOU Chao，SONG Xiaoyan DOI: 10.13228/j.boyuan.issn1006-6543.20200103 The optimum synthesis process of nanoscale NbC-Co composite powder by in situ reactions of Nb2O5， Co and carbon black was investigated in the present work. Then the obtained composite powder was used as an additive of WC-Co to prepare cemented carbide bulk material by HIP-sintering. The effects of the additive on the microstructure and property of the WC-Co cemented carbide were studied. By means of thermodynamic calculations and in situ reaction experiments，it shows that the transition of Nb2O5 in the reactions with carbon black proceeds in the sequence of Nb2O5→NbO2→NbC. The addition of Co，not only decreases the reaction temperature，but also results in simultaneous occurrence of reduction and carburization reactions which normally take place in two steps. After the optimization of the carbon content and reaction temperature，the synthesized NbC-Co composite powder has no impurity phases，a low oxygen content and a mean particle size is 82 nm. The addition of nanoscale NbCCo lead to a decrease in grain size from 0.70 μm to 0.48 μm and a more homogeneous microstructure in the prepared WC-Co cemented carbide. Moreover，the hardness of the cemented carbide is significantly enhanced at both room and high temperatures due to the addition of nanoscale NbC-Co. Particularly at 800 oC，the WC-12Co-1NbC cemented carbide still maintaines a hardness of 890HV30. 2021 Vol. 31 (01): 9-16 [Abstract] ( 3 ) HTML (1 KB)  PDF (2336 KB)  ( 6 ) 17 Investigation on reduction process of TiO2-WO3-NiO-C for preparation of （Ti，W）C-Ni composite powders Hot! CHEN Min，XIAO Xuan，LIU Li，DAI Yunyu DOI: 10.13228/j.boyuan.issn1006-6543.20190207 The phase evolution in the reduction of TiO2-WO3-NiO-C mixtures was investigated using SEM，TGDSC and X-ray diffraction analysis. Results show that Ni is reduced from partial NiO in the mixture. Stable NiWO4 solid solution is formed at lower temperatures with combination of WO3 and NiO. With the increasing of temperature， NiWO4 is reduced to Ni and WC. The crystal structure of TiO2 is transformed from anatase to rutile. When TiC is formed，（Ti，W）C solid solution is synthesized by TiC and WC. 2021 Vol. 31 (01): 17-20 [Abstract] ( 2 ) HTML (1 KB)  PDF (1519 KB)  ( 4 ) 21 Braking behaviors of Cu-based powder metallurgy brake pads mated with different discs for high-speed train Hot! ZHAO Sanqing，YAN Qingzhi，PENG Tao DOI: 10.13228/j.boyuan.issn1006-6543.20200063 Stable braking and lightening of unsprung mass are the development direction of high-speed train braking systems. Carbon ceramic materials（C/C-SiC）have been used in advanced braking systems such as high-end cars and airplanes due to light weight，appropriate toughness，and high thermostability. However，its application in high-speed train needs to be estimated. In this study，powder metallurgy brake pads，steel brake disc，and C/CSiC brake disc were used. The brake tests were performed at initial braking speeds of 80，120，160，200，250， 300，320，350，380 km/h. The results show that the powder metallurgy pad and C/C-SiC disc displayed higher friction coefficient，and higher friction stability. The friction coefficient stability factor is 0.908 for the ceramic disc group，which is higher than the corresponding value of steel disc，0.895. The wear test shows that the wear rate of the brake pad mated with the ceramic disc is up to 0.147 cm3/MJ，while the wear rate of the pad with the steel disc is 0.338 cm3/MJ，which is 2.3 times that of the ceramic group. When mated with C/C-SiC ceramic disc， the surface is slightly damaged after high-speed braking. Maintaining a stable friction area，the friction coefficient is stable as well. Meanwhile，transferred material on the ceramic disc is less，resulting in lower wear rate. According to the results，the application of C/C-SiC ceramic brake discs to high-speed braking systems shows significant advantages. 2021 Vol. 31 (01): 21-27 [Abstract] ( 3 ) HTML (1 KB)  PDF (2312 KB)  ( 4 ) 28 Precise design of the tooth profiles of compaction molds for powder metallurgy gears Hot! YE Hanlong，CHENG Jigui，CHEN Pengqi DOI: 10.13228/j.boyuan.issn1006-6543.20200272 The design error values of severd design methods according to the design formula of PM cylindrical compaction mold was calculated，and tried to reduce the errors by combining the different design methods. At last an optimized design method with no（zero）design error was obtained. This paper realized the precise design of the tooth profiles of powder metallurgy gear molds，and provided a feasible method for the precise design of PM gear formation mold. 2021 Vol. 31 (01): 28-33 [Abstract] ( 1 ) HTML (1 KB)  PDF (1315 KB)  ( 3 ) 34 Fracture failure analysis of shift pawl made by powder metallurgy Hot! ZHAO Hongli，WU Mei，WANG Yuanhao，LUO Cheng DOI: 10.13228/j.boyuan.issn1006-6543.20200008 The failure analysis of the shift pawl was carried out by the analysis of the macroscopic and microscopic fracture morphologies as well as metallographic structure，hardness distribution and tightness. The results show that the load of shift pawl is mainly caused by the reverse inversion of ratchet wheel in the process of driving shift. The fracture of the pawl is in the middle of the step near the pawl rocker arm. The fracture surface is rough and there is no obvious plastic deformation observed. The sintered neck at the broken part of the pawl is not fully formed. The pores near the fracture surface of the pawl are larger than the normal part，and unevenly distributed. There are even connected pores in the local area. The microstructure is mainly tempered martensite，plus copper and nickel riched phases，separately. Hardness varies in different regions. The main reasons lead to the fracture of the pawl are discussed and improvement measures are provided，warm compacting should be carried out at 140 ℃ and sintering at 1160 ℃，instead of compacting at room temperature and sintering at 1 140 ℃. 2021 Vol. 31 (01): 34-38 [Abstract] ( 2 ) HTML (1 KB)  PDF (2227 KB)  ( 3 ) 39 Effect of CeO2 doping on dispersion of ZrO2 ceramic bearing particles Hot! YU Dongling，ZHANG Xiaohui，WU Nanxing，LIAO Dahai DOI: 10.13228/j.boyuan.issn1006-6543.20190261 In order to investigate the relationship between the content of CeO2 and the dispersion of dry granulation of ZrO2 ceramic bearings，ZrO2 ceramic bearings with different content of CeO2 were prepared by dry granulation. High-precision screen was used to screen billet particles，and scanning electron microscopy was used to observe the micro-morphology. The SEM image was converted into binary image by Image J image analysis software， and the dispersion parameters were obtained. Particle gradation analysis and dispersion D method were applied to evaluate the dispersion of billet particles. The results show that when the content of doped CeO2 is 7%，the particle size distribution curve is approximately normal distribution，and the qualified rate of particles is the highest. Dispersion D0.1 and D0.2 are the highest，which are 9.67% and 17.35% respectively. The best dispersion uniformity of billet particles is obtained. CeO2 doping can effectively improve the particle dispersion of ZrO2 ceramic bearings during dry granulation process. 2021 Vol. 31 (01): 39-45 [Abstract] ( 2 ) HTML (1 KB)  PDF (1899 KB)  ( 3 ) 46 Effects of sintering temperatures on performance of WC-6Ni non-magnetic cemented carbide by Sinter-HIP Hot! LI Jinpu，SHI Yulei，LIU Xuequan，JIANG Lijuan，LI Biao DOI: 10.13228/j.boyuan.issn1006-6543.20190183 WC-6Ni non-magnetic cemented carbide was fabricated mainly from ultra fine WC power and carbonyl nickel power with a small amount of additives，carbon powder and tungsten powder through sinter-HIP. The influences of sintering temperature and carbon distribution amount on the density，hardness and bending strength of WC-6Ni non-magnetic cemented carbide were investigated in the present study. Experimental researches show that the density，hardness and bending strength of WC-6Ni non-magnetic cemented carbide show different trends with the increasing sintering temperature. The metallographic porosity rating of the alloy is A02B00C00 with the addition of 5.98% carbon. 2021 Vol. 31 (01): 46-50 [Abstract] ( 1 ) HTML (1 KB)  PDF (1239 KB)  ( 4 ) 51 Effect of mixing processes on microstructure and mechanical properties of SiCp/Al composites with rare earth Hot! XIEWenfang，LIU Pei DOI: 10.13228/j.boyuan.issn1006-6543.20190211 SiC powder，Al-Si alloy powder and CeO2 powder were mixed using three mixing methods（mechanical mixing，dry ball-milling and wet ball-milling）and with different mixing time under the condition of dry ballmilling， the SiCp/Al composites with rare earth were fabricated by powder metallurgy. The samples were tested by SEM，tensile and hardness measurement to study the effects of different mixing method on microstructure and mechanical properties of SiCp/Al composites. The results show that SiC and Si particles in the composite can be simultaneously refined by dry ball-milling，and thus the composite shows the best mechanical properties. The wet ballmilling has the worst refining effect on SiC and Si particles due to the medium alcohol`s obstruction on the ball， and thus the composites have the worst mechanical properties. The refining effect on SiC and Si particles of mechanical mixing and the performance of composites are just between the above two mixing methods. Under the condition of dry ball-milling，the increase of ball-milling time is beneficial to the fragmentation and refinement of SiC particles，but when the mixing time exceeds 6 h，the refining effect of SiC is not significant and the performance can not improve obviously. 2021 Vol. 31 (01): 51-55 [Abstract] ( 3 ) HTML (1 KB)  PDF (2259 KB)  ( 5 ) 56 Effect of solution and aging temperature on microstructure and properties of a new powder superalloy Hot! ZHONG Zhiyong，LIU Jiantao，ZHANG Yiwen，LI Xiaokun，JIA Jian DOI: 10.13228/j.boyuan.issn1006-6543.20190069 The effect of solution and aging temperature on the microstructure of the new designed alloy was studied by JMatPro、OM、FEG-SEM and EPMA . The relationship between microstructure and mechanical properties of the alloy was analyzed. The results show that the non-dissolved large-size γ′ phases in the alloy lead to the reduction of secondary γ′ phase after heat treatment at 1 160-1 190 ℃＋ 740-920 ℃，which meant the strengthening effect of γ′ phase is reduced. After heat treatment at 1 190-1 220 ℃＋ 740-920 ℃，the secondary γ' phases grow up to 240 nm and tertiary γ' phases grow up to 70 nm. Secondary γ' phases split because its center of <100> edge pitted inward. After heat treatment at 1 190-1 220 ℃＋740-890 ℃，the volume fraction of secondary and tertiary γ′ phases is 56% ，and the morphology of secondary γ′ phases is stable and regularly arranged，which significantly increases strengthening effects of the γ′ phase and the high temperature strength of the alloy. After that heat treatment， the rupture life of the alloy is up to 437 h under the condition of 750 ℃/750 MPa，and the comprehensive mechanical properties are the best. 2021 Vol. 31 (01): 56-63 [Abstract] ( 3 ) HTML (1 KB)  PDF (3083 KB)  ( 6 ) 64 Effect of solution treatment on microstructure and corrosion resistance of duplex stainless steel fabricated by cold isostatic pressing Hot! ZHANG Peng，WANG Zhiyong，SHANG Feng，LI Huaqiang，HE Yiqiang DOI: 10.13228/j.boyuan.issn1006-6543.20190079 The 316L and 430 water atomized stainless steel powders were mixed according to the mass ratio of 65： 35，and the duplex stainless steel was prepared by the cold isostatic pressure-vacuum sintering process，the solution treatment was carried out in 1 150-1 300 ℃，with a insulation for 1 h at a time. The evolution of microstructure of duplex stainless steel with different solution treatment temperature was studied，and the effect of solution treatment temperature on corrosion resistance of duplex stainless steel was studied by dynamic potential polarization and electrochemical impedance. The results show that with the increase of solution treatment temperature，the content of ferrite phase increases gradually，the content of austenite phase decrease gradually，the grain grows gradually；and the two phase ratio of ferrite to austenitic is 39.1：60.9 at 1 300 ℃ ，and at this moment，duplex stainless steel has good corrosion resistance. 2021 Vol. 31 (01): 64-68 [Abstract] ( 2 ) HTML (1 KB)  PDF (1839 KB)  ( 4 ) 69 Effect of Zr on microstructure and mechanical properties of sintered Al-5Si aluminum alloy for automobile body Hot! WU Zhiguang，ZHOU Jianmin，ZHANG Fangdong DOI: 10.13228/j.boyuan.issn1006-6543.20200013 The comprehensive properties of sintered Al-5Si aluminum alloy used for mobile body were improved by adding Zr element. The microstructure and slow strain rate tensile（SSRT）test were used to analyze the microstructure and mechanical properties. The results show that Zr can inhibit the recrystallization process and reduce the recrystallization grain size. More black second-phase particles are formed in Al-5Si-Zr plate，and the recrystallized grains increases obviously. The second phase structure of dispersion distribution is found in all the plates， which has obvious needle structure，and the number decreases after Zr is added.Zr can nail the quenching vacancy of Al-5Si-Zr plate，form less movable vacancy，make it difficult for the grain boundary phase to nucleate. The tensile strength and elongation of the plate in NaCl solution are lower than that in the air.After the addition of Zr，the tensile strength of the plate in air decreases from 346 MPa to 321.5 MPa，and the elongation decreases from 12.2% to 11.41%. At the fracture site of Al-5Si-Zr plate，a dense distribution of dimples is formed，resulting in transgranular ductile fracture，and the fracture size and depth are reduced. 2021 Vol. 31 (01): 69-73 [Abstract] ( 1 ) HTML (1 KB)  PDF (1925 KB)  ( 3 ) 74 Influence of Al powder content on the performance of auto Al2O3 hot-pressing injection molding core Hot! LI Yang，DU Shaojie DOI: 10.13228/j.boyuan.issn1006-6543.20190032 The Al powder was selected as Al2O3 powder material modifier to test the changes of shrinkage，microstructure and mechanical properties of Al2O3 powder material under different addition amounts of Al powder. The results show that the casting shrinkage of the sample changes significantly with the addition of Al powder，in which the casting shrinkage is the largest in the width and the thickness is the smallest.With the gradual increase of Al powder content，the bending strength and volume density of Al2O3 powder sample decreases significantly，the porosity increases significantly，the powder deflection of Al2O3 also increases significantly，the pore diameter of the casting structure also increases significantly，and the pore diameter of a larger size is formed. With the increase of the content of Al powder，the intensity of alumina diffraction peak increases. When Al powder is not added， some large particles are formed at the fracture site，which showes the characteristics of transgranular fracture. The fracture of the material with Al powder is intergranular fracture. 2021 Vol. 31 (01): 74-77 [Abstract] ( 3 ) HTML (1 KB)  PDF (1335 KB)  ( 5 ) 78 Study on effect of powder particle size on mechanical properties of molybdenum shield Hot! GONG Yanfei，QU Binrui，LIANG Yanming，WANG Chengyang， DONG Di，SUN Xiaoxia DOI: 10.13228/j.boyuan.issn1006-6543.20200149 In this paper，the molybdenum shield made of different sizes of molybdenum powder was tested in 60 s solid rocket ground motor test. The correlation between the powder size and the mechanical properties of molybdenum shield was obtained through the metallographic structure，mechanical property test and fracture structure analysis of ablation results. The results show that with the increase of the particle size of the original powder，the ablation resistance and the mechanical properties of the Mo guard plate used in the SRM with 60 s working time are improved. 2021 Vol. 31 (01): 78-81 [Abstract] ( 4 ) HTML (1 KB)  PDF (2024 KB)  ( 2 ) 82 Study of thermoelectric properties of nanocrystalline Sb2Se3 doped PZT ferroelectric ceramics Hot! WU Yali，YUE Caixia ，JIN Hong DOI: 10.13228/j.boyuan.issn1006-6543.20200068 In order to enhance the thermoelectric properties of piezoelectric ceramics（PZT）ferroelectric ceramics， Sb2Se3 was doped into PZT ferroelectric ceramics by solid sintering technology. XRD analysis of the doped samples show that the Sb2Se3 doped into PZT is effectively. And then the thermoelectric properties of the sample materials are analyzed in detail. The results show that with the increase of temperature，the absolute values of Seebeck coefficient of samples increase gradually，and are all negative. The absolute values are lower than that without PZT. The thermal conductivity of the sample with smaller volume is lower than that of the larger sample obviously. With the amount increase of doping Sb2Se3 into PZT ferroelectric ceramics，the conductivity increases firstly and then decreases. The maximum ZT value of PZT material with 0.3 doping is 0.28 at 615 K（342 ℃） 2021 Vol. 31 (01): 82-85 [Abstract] ( 6 ) HTML (1 KB)  PDF (1369 KB)  ( 13 ) 86 Progress of PM aluminum alloy in automotive industry Hot! WANG Qi，JIANG Feng，SUN Jun DOI: 10.13228/j.boyuan.issn1006-6543.20190224 Automobile lightweighting is one of the effective measures to reduce energy consumption and reduce emissions. The use of aluminum alloy powder metallurgy parts to replace iron-based powder metallurgy parts used in automobiles is the development trend currently. This paper mainly introduces the development and research status of the aluminum alloy powder metallurgy technology，and gives some suggestions on the possible development and application direction of the technology in the automobile field. 2021 Vol. 31 (01): 86-90 [Abstract] ( 3 ) HTML (1 KB)  PDF (1390 KB)  ( 4 ) 91 Progress of production and purification technology of tantalum powder Hot! SU Longxing，YAN Xiaoyong DOI: 10.13228/j.boyuan.issn1006-6543.20190104 Different industrial methods of preparing tantalum powder were systematically introduced. These techniques， including sodium reduction of potassium fluo tantalate，sodium/magnesium reduction of tantalum oxide， electrical deoxidation of tantalum oxide and so forth，were developed during past decades. Advantages and disadvantages were compared and analyzed in respect of production efficiency and reaction mechanism to select the most optimal method. Subsequently，purification techniques for preparing tantalum powder were introduced. The progresses of acid leaching，deionized water washing and oxygen removing were described in details. Finally，metallic elements of Fe，Cu，Ni，Cd and nonmetallic elements of C，O，Si were discussed in deep to evaluate the current purification techniques. 2021 Vol. 31 (01): 91-97 [Abstract] ( 7 ) HTML (1 KB)  PDF (1199 KB)  ( 12 ) 98 Application of porous sintered metal filter element on E-Gas gasification char filter Hot! ZHOU Jianxin，XIONG Jiang，WANG Haiqing，HU Bo，GUO Zongbin，WANG Kun DOI: 10.13228/j.boyuan.issn1006-6543.20200084 This paper studied the problems in the operation of the char filter element of the E-Gas gasification unit of Huizhou Petrochemical Company，and used the operation experience of the porous sintered metal filter element in the coal gasification fly ash filter of China for reference. After optimization and improvement，it was first applied in the char filter of the E-Gas gasification unit. The results show that the porous sintered metal filter element appear better performance than that of the original sintered metal fiber filter，and the use of domestic porous sintered metal filter can also significantly reduce the production cost of the gasification facilities. 2021 Vol. 31 (01): 98-102 [Abstract] ( 1 ) HTML (1 KB)  PDF (1774 KB)  ( 4 ) 103 Recent development of new type powder metallurgy superalloys in Russia Hot! ZHANG Yiwen，JIA Jian，LIU Jiantao，QU Jinglong DOI: 10.13228/j.boyuan.issn1006-6543.20200193 This article reviews the research progress of powder metallurgy（PM）superalloys in Russia from 2015 to 2019. The microstructure and mechanical properties of ВВП nickel base PM superalloys are overviewed，such as ВВ750П，ВВ751П，ВВ752П and ВВ753П，which are developed by Russian Institute of Light Alloy（ВИЛС）. It is also reviewed the microstructure and mechanical properties of a new kind of PM superalloy named ВЖ178П， which is developed by Russian Institute of Aeronautical Materials（ВИАМ）. ВИЛС prepared disk billet by plasma rotating electrode process（PREP）and as-hot isostatic pressing（as-HIP）. Since October 2014，ВВ751П alloy powder with particle size of no more than 70μm has been used by ВИЛС to produce disk for ПД14 engine. ВИАМ adopts argon atomization（AA）and PREP to prepare alloy powders. The particle size distribution，gas content in powders，preparation technology，microstructure characteristics，microstructure and process plasticity of HIP billet， and microstructure and mechanical properties of forgin ingot were compared between AA powders and PREP powders. ВИАМ developed the disk billet（320 mm in diameter）of ВЖ178П alloy by HIP and isothermal forging process，and the mechanical properties of this alloy were better than those of the same kind in Russia and abroad. Compared with AA powders，PREP powders ensure that the deformed disk has higher mechanical properties at room temperature. Using PREP ВЖ178П powders and as-HIP process，full-scale experimental disk billet（600 mm in diameter）was first developed，and its mechanical properties met the modern requirements of areo-engine disk materials. 2021 Vol. 31 (01): 103-114 [Abstract] ( 3 ) HTML (1 KB)  PDF (5429 KB)  ( 5 )

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