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2019 Vol. 24, No. 1
Published: 2019-01-15
Engineering and Technology
1
Preparation and characterization of Cu6AlNiSnInCe imitation-gold powder by vacuum nitrogen gas atomization for 3D printing
CUI Bo, ZHU Quanli, CHEN Jin, MAO Weidong, Li Bo, XIAO Zhiyu
A novel Cu6AlNiSnInCe imitation-gold powder for 3D printing was fabricated by vacuum gas atomization. And its color, morphology, particle size distribution and microstructure were characterized by using spectrophotometer, scanning electron microscopy (SEM), laser particle size analyzer, laser particle shape analyzer and DTA. The formability of specimens was also studied in selective laser melting (SLM). The results show that the color difference Δ
E
between Cu6AlNiSnInCe powder and pure gold is 28.9; the 80% (volume fraction) of the powder roundness fitting rate up to 85%, the 60% of the powder bluntness fitting rate up to 70%, and the shape of the powder particles are spherical or nearly spherical, the fluidity of powder is 16 s/50 g, apparent density is 4.39 g/cm
3
, tap-density is 4.67 g/cm
3
, average oxygen content is 0.01%. The yield of powder with particle size between 15 and 53 μm is 40%. The microstructure of the powders is composed of cellular and dendritic grains, which is a matrix of α-Cu solid solution and a Sn-rich phase distributed along grain boundaries. The relative density of Cu6AlNiSnInCe alloy formed by Selective laser melting (SLM)increases with increasing laser power or decreasing laser scanning speed, and the maximum relative density reaches 89.6%。
2019 Vol. 24 (1): 1-7 [
Abstract
] (
293
)
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552
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8
Effects of sintering temperature on microstructure and mechanical properties of Ti600 alloy fabricated by powder metallurgy
DING Chao, ZOU Liming, LIU Xin, HANG Zhengxiang, WU Wei, LI Runxia
Ti600 alloy (with a nominal composition of Ti-6Al-2.8Sn-4Zr-0.5Mo-0.4Si-0.1Y) was prepared by cold isostatic pressing and vacuum sintering using the mixed element powder method. The effects of sintering temperature on the microstructure, density and mechanical properties of the alloy were investigated. The results show that the microstructure of Ti600 alloy is composed of disordered α lamellar at the sintering temperature of 1 100 ℃, the α lamellar begins to arrange regularly to α colonies at the sintering temperature of 1 200 ℃, the α lamellar basically forms to α colonies at the sintering temperature of 1 300 ℃. The Zr and Mo elements dissolve in the β-Ti phase, the Al element dissolves in the α-Ti phase, and the Si element enriches in the precipitates, the Sn and Y elements distribute uniformly. With increasing the sintering temperature, the numbers of pores and α-Ti phase in the alloy gradually decrease, the amount of β-Ti phase gradually increases, and the density and the mechanical properties of the alloy increase. The alloy sintered at 1 300 ℃ has the relative density of 92.8%, the hardness (HV) of 324.0, the tensile strength of 622.6 MPa and elongation of 5.0%.
2019 Vol. 24 (1): 8-14 [
Abstract
] (
333
)
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1112
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15
Effects of selective laser melting energy density on density and microstructure and properties of pure tungsten
NIU Pengda, LI Ruidi, YUAN Tiechui, WANG Minbo
Some refractory metals are widely used in the fields of weaponry, communication and medical fields due to their high melting point, low steam pressure and excellent high temperature strength. Using selective laser melting (SLM) technique to print pure tungsten can solve the problems of traditional powder metallurgy technology for some complicated shapes and ultra-fine grains. The effects of energy density of SLM on the density, hardness and microstructure of the pure tungsten were studied. The results show that the density and microhardness increase with the increase of volumetric energy density (VED). The maximum relative density can reach 75%, and the microhardness reaches 485 HV, far more than traditional powder metallurgy (260 HV). The microstructure after SLM is a fine equiaxed grain with the grain size less than 1μm.
2019 Vol. 24 (1): 15-20 [
Abstract
] (
511
)
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(687 KB) (
992
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21
Effects of electrolyte circulation form on energy consumption and properties of electrolytic copper powder
XIANG Xiaoyan, XIA Wentang, YANG Wenqiang, YIN Jianguo
The electrolytic copper powder was prepared by using a new type of electrolytic cell with parallel feed device under the condition of total flow rate of 18 L/min. The effects of electrolyte feeding mode on cell voltage, current efficiency, energy consumption and copper powder properties were studied. The energy saving and consumption reduction of copper powder electrolysis process were also explored. The results show that the energy consumption is 3.01×106 kJ/t, the current efficiency is 94.42%, the particle size of copper powder is 3.47 μm, and the particle size distribution is concentrated by wing traditional injection method. The cell voltage and energy consumption of electrolysis process can be effectively reduced by using the traditional mode of parallel and bilateral flow. With the increase of the flow rate of bilateral parallel flow, the current efficiency increases and the energy consumption decreases, but the particle size of copper powder increases. When the flow rate of the spray nozzle is 6 L/min, the electrolysis energy consumption of 2.55×106 kJ/t is low, the average particle size of copper powder is 4.65 μm, the particle size of more than 95% copper powder is less than 7.2 μm, and the copper powder has obvious dendritic structure. There is no obvious difference in the properties of copper powder obtained from traditional electrolysis. When the nozzle flow rate further increases to 9 L/min, the energy consumption of electrolysis decreases to 2.17×106 kJ/t, and the current efficiency increases to 96.95%, but the particle size of copper powder increases to 45.76 μm, and the particle size distribution is obviously graded.
2019 Vol. 24 (1): 21-26 [
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] (
416
)
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1778
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27
Effects of
w
(Co)/
w
(Ni) ratio on high-temperature oxidation and corrosion resistant behavior in Ti(C,N)-based cermets
LIU Yi, ZHANG Meimei, KANG Xiyue, LIN Nan, YAN Yan, QIU Song, HUANG Jianhua, HE Yuehui
The effects of Co and Ni binder ratio on microstructure and properties in Ti(C,N) based cermets has been studied. The corrosion behaviors of cermets in high temperature and acid solution have been analyzed systematically. The results indicate that cermet with
w
(Co)/
w
(Ni) ratio of 1 has excellent mechanical properties, which TRS and hardness are 1 749 MPa and 93.8 (HRA), respectively. The corrosion resistant of cermets in H
2
SO
4
acid solution increases obviously with adding Ni into binder phase, whereas the mass loss of T3 cermet with
w
(Co)/
w
(Ni) ratio of 1 is 0.074 5% after immersion for 120 h. The corrosion mechanisms of cermets in acid solution are the dissolution of binder phase and partly rim phases. The passive regions in anodic polarization curves appear combination with the decrease of
w
(Co)/
w
(Ni) ratio, which is proved that the increase of Ni content can promote the solid solution of the elements to the binder phase. The T3 cermet has excellent corrosion resistance, and the self corrosion current density is 3.356 6×10
-7
A/cm
2
. Finally, after oxidized in static air for 10 h under 900 ℃, the mass losses of all cermets with surface area of 2.5 cm
2
are lower than 1mg. Moreover, the corrosion behaviors of cermets in high temperature are the prior oxidation of binder phase and the oxidation of Ti, W-riched solid solution phases.
2019 Vol. 24 (1): 27-36 [
Abstract
] (
334
)
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1033
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37
Microstructure and photothermal effect of photothermal agent nanocrystalline WO
3-
x
prepared by hydrothermal method
HU Wei, HUANG Zhi
PTMP-PMAA modified Nano-WO
3-
x
powder was obtained by hydrothermal method. The effects of pH value and concentration on photothermal properties of the nano-WO
3-
x
powder materials were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and photothermal property testing. The results show that the powders prepared by hydrothermal method are spherical nonintegral structure W
17
O
48
with a particle size of less than 10 nm. The UV absorbance of the WO
3-
x
material increases and the photothermal effect increases with decreasing the pH value or concentration of WO
3-
x
. When pH 6.4 and mass concentration is 800 μg/mL, the temperature of WO
3-
x
can rise nearly 19 ℃ in 5 minutes after photothermal conversion. Considering that the body temperature is 37 ℃ and the pH value of tumor site is between 6.0 and 6.5, nano-WO
3-
x
powders at this concentration can be used in photothermal therapy and achieve the killing effect on tumor cells.
2019 Vol. 24 (1): 37-44 [
Abstract
] (
292
)
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1840
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45
Effects of isothermal compound forging on microstructure and mechanical properties of 2A14 aluminum alloy wheel hub
YU Yongxin, XIAO Daihong, ZHOU Pengfei, HUANG Lanpin, LIU Wengsheng
The 2A14 aluminum alloy wheel hub forging stock was prepared by isothermal compound forging (isothermal multi-direction forging + isothermal die forging) followed by solid solution and aging treatment. The effects of isothermal compound forging on microstructure and mechanical properties of the alloy were investigated by optical microscopy, scanning electron microscopy (SEM) and mechanical property testing. The results show that there are dynamic recovery and dynamic recrystallization in isothermal forging process. With increasing the die forging temperature, the softening mechanism of the alloy gradually changes from dynamic recovery to dynamic recrystallization. The mechanical properties can be improved by increasing isothermal multi-direction forging passes. Under the same isothermal multi-direction forging, the mechanical properties of the alloy increase first and then decrease with increasing the isothermal die forging temperature. The alloy treated by isothermal multi-direction forging with 6 passes at 450 ℃ and isothermal die forging at 460 ℃ has the best mechanical properties with the tensile strength and the elongation of 491 MPa and 12%, respectively.
2019 Vol. 24 (1): 45-51 [
Abstract
] (
411
)
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(989 KB) (
707
)
52
Effect of polyethylene glycol 2000 content on the properties of TiO
2
membrane
TONG Zhi, WANG Lei, FAN Lu, YANG Bowen, SUN Xiaojuan, XING Jing
TiO
2
membrane was prepared by sol-gel method through using tetrabutyl titanate as the precursor, PEG as an additive. Thermal stability, crystal phase change, specific surface area, pore structure, surface morphology, and hydrophilicity of the membrane were characterized by means of TG-DTG, XRD, BET, SEM and contact angle analysis etc. The results show that,with the increase of PEG2000 content, the temperature of TiO
2
membrane anatase crystal transformed into rutile crystal increases, the surface of membrane develops from dense and smooth to cracking and course, the specific surface area continues to increase and the average pore size decreases, the contact angle increases from 3° to 20.2°. When the PEG2000 content is 5%, TiO
2
membrane has the best performance and super hydrophilicity.
2019 Vol. 24 (1): 52-57 [
Abstract
] (
328
)
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1316
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58
Microstructure and mechanical properties of Al
2
O
3
matrix composite metal ceramic die materials
LIU Xianchao, GUO Rong
The alumina matrix composite metal-ceramic die materials were fabricated by hot-pressing sintering technique in N
2
atmosphere using nano Al
2
O
3
and Ti(C,N) as the main raw materials, Mo and Ni as sintering additives. The phase composition and microstructure were tested and analyzed by XRD and SEM. The mechanical property was also studied. The results show that when the sintering temperature is 1 660 ℃, the mass fraction of nano Al
2
O
3
is 74.5%, nano Ti(C,N) is 20% and Mo+Ni is 5%, the prepared alumina matrix composite metal ceramic die material can obtain the optimal properties. And the relative density is 98.14%, flexural strength is 795.98 MPa, hardness is 18.52 GPa and fracture toughness is 8.05 MPa·m
1/2
. Introduced second phase and Mo+Ni in the boundary of crystal can increase the crystal boundary strength, accelerate intergranular crack transit to transgranular cracks, then enhance mechanical properties of the samples.
2019 Vol. 24 (1): 58-62 [
Abstract
] (
373
)
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(1 KB)
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(332 KB) (
398
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63
Preparation and mechanical properties of in-situ carbon nanotube/aluminum composites
WANG Lei, YIN Hua, XU Run, TAN Zhanqiu, FAN Genlian, LI Zhiqiang, ZHANG Di
The carbon nanotube/aluminum (CNT/Al) composites were fabricated by flake powder metallurgy, and investigated the mechanical properties. First, flaky CNT/Al composite powders were prepared by in-situ growth of CNTs on the submicron sized Al flakes with the polymer pyrolysis chemical vapor deposition (CVD) methods. Then the flaky CNT/Al composite powders were compacted, sintered and extruded to fabricate dense bulk CNT/Al composites. The results show that, Compared with the Al matrices, the tensile strength and modulus of the 1.5%CNT/Al composites are increased by 18.5% and 23.7%, while the tensile strength and modulus of the 3%CNT/Al composites are increased by 31.4% and 74.1%. However, their tensile elongations decrease to 4.96% and 1.5%, respectively, which may be owning to the grain refinement and dislocation strengthening mechanisms.
2019 Vol. 24 (1): 63-68 [
Abstract
] (
356
)
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(455 KB) (
691
)
68
Effects of sintering temperature on microstructure and properties of high speed steel particles reinforced titanium matrix composites
ZENG Han, WU Hong, ZHOU Chengshang, LIU Yong, LIU Bin
The high-speed steel particle reinforced titanium matrix composites (HSS
P
/Ti-based composites) were prepared at 850~1 000 ℃ by spark plasma sintering (SPS) using M2 high-speed steel particles as reinforcements. The effects of sintering temperature on the microstructure, hardness and friction property of the composites were investigated. The results show that no pores or Ti-Fe intermetallic compounds are found in the interfacial transition layer between high-speed steel particles and titanium matrix, and the highest density of composites is 96.8%. A layer of carbide precipitates around the high-speed steel particles is founded at the sintering temperature of 850 ℃. The carbides disappear due to the diffusion of C phase with increasing sintering temperature. The W and Mo elements in the high-speed steel particles are enriched around the high-speed steel particles. The microhardness of the interface between the high speed steel particle and titanium matrix is relatively higher, and the microhardness of the titanium matrix sintered at 1 000 ℃ can reach 426.9 HV. The addition of high-speed steel particles is beneficial to improve the friction property of titanium. The wear mode of high speed steel particles reinforced titanium matrix composites is dominated by adhesive wear. The microhardness and wear resistance of the material both increase with sintering temperature increases.
2019 Vol. 24 (1): 68-74 [
Abstract
] (
373
)
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(625 KB) (
586
)
75
Performance of anti-erosion coating sprayed by explosive spraying on fluid machinery
FU Li, CHEN Xiaoming, MA Honghai, LIU Wei, MENG Jinbo
The WC-12Co coating was prepared by CCDS2000 explosive spraying technology on the stainless steel 0Cr13Ni5Mo, which is commonly used in fluid machinery such as pumps and turbines. The microstructure, micro hardness, porosity, bonding strength and erosion resistance of the coating were characterized and analyzed by optical microscopy, hardness tester, SEM, XRD, tensile testing machine and slurry erosion wear testing machine, and the erosion mechanism of the coating was also analyzed. The results show that the porosity of the WC-12Co coating is 0.63%, the micro hardness is 1 305.6 HV
0.2
and the bonding strength is 130 MPa. Additionally, the coating erosion resistance is 4.678 times than that of ZG0Cr13Ni5Mo stainless steel. The internal crack of the coating mainly expands along the transgranular fracture and crystal fracture. Therefore, the use of explosive spray to prepare WC-12Co coating has broad application prospects in fluid mechanical parts with high sediment flow.
2019 Vol. 24 (1): 75-79 [
Abstract
] (
305
)
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(457 KB) (
563
)
80
Synthesis and electrochemical performance of porous V
2
O
5
microspheres
CHEN RU, FANG Guozhao, TAN Xiaoping, ZHOU Jiang, Liang Shuquan
Porous V
2
O
5
microspheres were synthesized by a facile hydrothermal reaction followed by high temperature calcination. The crystal structure of V
2
O
5
microspheres was analyzed by X-ray diffraction (XRD). The morphology and microstructure were observed and analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the microspheres are single phase V
2
O
5
with homogeneous porous morphology. As cathode material for lithium batteries, porous V
2
O
5
microspheres electrode exhibits excellent electrochemical performance at different voltage ranges. The initial discharge capacity of the porous V
2
O
5
microspheres electrode is 145 (mA·h)/g at the current density of 100 mA/g during 2.5-4 V, which is very close to the theoretical value. The capacity retention is 95.2% based on the initial capacity after 50 cycles. In addition, the electrode demonstrates excellent long-term cycling stability with the discharge specific capacity maintained at 82.8 (mA∙h)/g after 1 000 cycles at 2 A/g current density, and the average single-cycle specific capacity attenuation rate is only 0.022%. The excellent electrochemical properties of the material benefit from the three-dimensional porous microsphere structure.
2019 Vol. 24 (1): 80-88 [
Abstract
] (
267
)
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(705 KB) (
1357
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89
Organic synthesis and pyrolysis properties of high carbon-zirconium ratio zirconium carbide precursor
LI Yiming, SU Zhean, YANG Xin, HUANG Qizhong, SHAO Junjie, WANG Yujie, FANG Cunqian
Using zirconium tetrachloride as zirconium source, and benzyl methanol as carbon source, precursor benzyl alcohol zirconium (BAZ) of high carbon zirconium ratio (28:1 atomic ratio) zirconium carbide ceramic was prepared by 3 different solvents (p-xylene solvent, m-xylene solvent and xylene solvent). The structure of the BAZ was characterized by FT-IR. The heat-resistant property was studied by TGA and the transformation of ceramic was studied by XRD. The results show that all zirconium carbide precursors prepared by different solvents are pyrolysised during 600-700 ℃ and turn to ZrC after 1 500 ℃ heat treatment. The precursor prepared by p-xylene solvent has the highest ceramic yield of 51.8% after 1 600 ℃ heat treatment with argon gas protection. The precursor prepared by xylene solvent has the highest pyrolysis temperature that is 670 ℃.
2019 Vol. 24 (1): 89-94 [
Abstract
] (
390
)
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2300
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