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2021 Vol. 26, No. 5
Published: 2021-10-15
Engineering and Technology
Theoretical Research
Theoretical Research
387
First-principles calculations of Ni, Co and Al doped spinel LiMn
2
O
4
LI Xu, WANG Jianchuan, DU Yong
For spinel LiMn
2
O
4
doped with Ni, Co and Al, the first-principles calculations method based on density functional theory is used to analyze the magnetic configuration of the anti ferromagnetic layer and the ferromagnetic layer alternately arranged along the [001] direction rationality. The result show that this magnetic structure shows the valence distribution of Mn
3+
/Mn
4+
alternately arranged along the [001] direction. The doping calculation shows that all three kinds of atoms tend to replace Mn in the Mn
3+
layer, and the valence states of doped atoms are Ni
2+
, Co
3+
and Al
3+
after occupying the 16d site. Al and Ni doping can inhibit the Jahn-Teller distortion of doping sites, and its nearest neighbor Mn
3+
is oxidized to Mn
4+
after Ni doping, which is more conducive to the stability of the structure. Co doping may result in more severe Jahn-Teller aberrations. The Al
3+
and Co
3+
can significantly reduce the diffusion energy barrier of Li ion in two paths, and Ni
2+
further reduce the low energy barrier path’s energy barrier under the synergistic action of Mn
4+
.
2021 Vol. 26 (5): 387-395 [
Abstract
] (
492
)
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1906
)
396
Diffusion kinetics of BCC phase in Cr-Al and Cr-V systems
JIN Youliang, LIU Yuling, DU Yong, LIU Huixin, WEN Shiyi, MIN Qianhui, DU Changfa, ZHANG Shuyan, CHU Mingqiang
On the basis of Cr/Cr-Al and Cr/Cr-V diffusion couples together with electron probe microanalysis technique, the composition-dependent interdiffusion coefficients in BCC phases of Cr-Al and Cr-V alloys were measured between 1 273 and 1 473 K via the Sauer-Freise method, and the method of error propagation was applied to evaluate the errors of the measured interdiffusivities. Based on the available thermodynamic information, self-diffusion and impurity-diffusion mobilities, and the measured interdiffusion coefficients, the atomic mobilities for the Cr-Al and Cr-V system BCC phases are obtained by using the DICTRA (calculation of phase diagrams) software with the method of CALPHAD (diffusion controlled transformation). Furthermore, the interdiffusion coefficient and component distance curves of diffusion pairs after diffusion annealing under different conditions are predicted. By comparing the predicted results with the experimental data, it is found that the predicted interdiffusion coefficient and component distance curve are in good agreement with the experimental data. The results show that the atomic mobility parameters optimized by DICTRA software can well predict the diffusion process of the Cr-Al and Cr-V system BCC phases at different temperatures, which illustrates the reliability of the atomic mobility parameters obtained in this work. This work contributes to enriches the kinetic databases of the Ti-based alloys.
2021 Vol. 26 (5): 396-403 [
Abstract
] (
388
)
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940
)
Engineering and Technology
404
Residual stress and dynamic mechanical properties of swaging deformed tungsten alloy
LIN Zehua, KANG Jun, ZHOU Yonggui, ZHOU Chengshang, YAN Wenmin
95W-3.5Ni-1.5Fe tungsten alloy was prepared by cold isostatic pressing and vacuum sintering using W, Ni and Fe powders as raw materials. Then, the swaging processing with 15%, 30% and 40% deformation was carried out. Scanning electronic microscope with electron backscattered diffraction, split Hopkinson pressure bar and live-fire target test were used to analyze the microstructure, dynamic mechanical properties and residual stress distribution of 95W-3.5Ni-1.5Fe tungsten alloy. The results show that the W particles in the tungsten alloy deform from a spherical shape to an olive shape after swaging process. The static tensile strength and hardness (HRC) of the 40% deformation tungsten alloy increase from 983 MPa and 28.9 to 1 434 MPa and 46.1 HRC respectively, and the elongation decreases from 11.9% to 4.6%. There are residual compressive stresses in the alloy, which are mainly distributed between tungsten particles and in the Ni-Fe bonding phase. The deformed tungsten alloy has a higher strain rate of 4.9% under the impact strain rate of about 1.2×10
3
s
-1
, and exhibits “self-sharpening” when penetrating the steel target.
2021 Vol. 26 (5): 404-411 [
Abstract
] (
425
)
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1037
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412
Diffusion behavior of FCC Ni-Al system in spark plasma sintering electric field
WANG Fei, LIU Yuling, DU Changfa, MIN Qianhui, LIU Huixin, WEN Shiyi, DU Yong
The smelting method was employed to prepare the Ni-9Al (mole fraction, %) alloys and pure Ni, and then the Ni/Ni-Al/Ni diffusion couples were annealed for diffusion in spark plasma sintering (SPS). The concentration profiles of FCC Ni-Al system at 1 173-1 373 K under the effect of SPS current were obtained combining with electronic probe microanalysis (EPMA). The Sauer-Freise method and empirical formula were employed to calculated diffusion coefficients respectively. The concentration profiles without current were simulated based on the atomic mobilitiy parameters without the influence of applied field and then the diffusion coefficients were calculated meanwhile. Comparing the simulated concentration profiles with the experimental ones. The results show that the current promotes the diffusion of Ni-Al alloys. The direction of the current has negligible effect on the diffusion of Ni-Al alloys. The concentration profiles and diffusion coefficients under different current directions have a high degree of overlap, indicating that the influence of electromigration on the diffusion of Ni-Al alloy is negligible. The applied current has little effect on the diffusion frequency factor, while the applied current significantly reduces the diffusion activation energy.
2021 Vol. 26 (5): 412-418 [
Abstract
] (
353
)
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716
)
419
Experimental investigation of phase relations in the Cu-Cr-Ti system
LI Jiahui, HU Ting, CAI Gemei
Through electron probe (EPMA) and X-ray diffraction (XRD) analysis of the Ti-Cr-Mn equilibrium alloy, the isothermal cross-sections of the Ti-Cr-Mn ternary system at 1 373, 1 173 and 973 K were constructed. According to present results, TiMn
2
(Laves C14) has a large solid solubility for Cr, mole fraction about 58% at 973 K, even reaching 60.5% at 1 373 K. In addition, TiMn
2
and TiCr
2
can not form a continuous solid solution due to their difference in crystal structure. The TiMn
1-
x
phase exists stably at 1 373 K. The solid solubility of Ti in the high temperature σ-H phase is 6.7% (mole fraction), which is higher than its solubility in the low temperature σ-L phase. In the temperature range of 973- 1 373 K, there is no ternary compound found in this ternary system. The phase relationship of Ti-Cr-Mn ternary system in the range of 973-1 373 K determined in this study can provide certain theoretical guidance for the preparation of Ti-Mn-based hydrogen storage alloys in this temperature range.
2021 Vol. 26 (5): 419-427 [
Abstract
] (
344
)
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(741 KB) (
754
)
428
Effect of adding the Fe-Ni powder on the structure and properties of Fe-4Ni-0.4 C low-alloy steel
WANG Xinyue, LI Songlin, LIU Xiangyang, YU Yongliang, YUAN Yong, ZHENG Risheng
Add Fe-20Ni pre-alloyed powder to replace part of Ni powder as Ni source to prepare powder metallurgy Fe-4Ni-0.4C low-alloy steel. Measure the density, hardness and tensile strength of low-alloy steel, observe and analyze the microstructure and structure of the material through optical microscope (OM), X-ray energy spectrum analysis (EDS) and scanning electron microscope (SEM). The effects of adding nanocrystalline Fe-20Ni pre-alloyed powders on the structure and properties of low-alloy steel were also studied. The results show that the addition of Fe-20Ni pre-alloyed powders can make the alloy structure evenly distributed, and reduce the enrichment of Ni. When the addition amount of Fe-20Ni pre-alloyed powders (mass fraction, the same below) is 10%, and the pressing pressure is 800 MPa, the overall mechanical properties of the alloy are the best. Compared with the material without Fe-20Ni pre-alloyed powders, the tensile strength is increased by 14.9 MPa.
2021 Vol. 26 (5): 428-435 [
Abstract
] (
383
)
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(1106 KB) (
553
)
436
Property of high-enthalpy plasma spraying Cr
2
O
3
·5SiO
2
·3TiO
2
/CoNiCrAlY gradient ceramic coating on the surface of the piston rod of the gate hoist
CHENG Xinchuang, FU Li, CHEN Xiaoming, ZHAO Jian, MAO Pengzhan, LIU Wei, ZHANG Lei
In order to solve the problem of the wear of the piston rod of the gate hoist during the Cao’e river sluice, the high-enthalpy plasma spraying technology was used to prepare a gradient ceramic coating with a bonding layer of CoNiCrAlY and a surface layer of Cr
2
O
3
·5SiO
2
·3TiO
2
. The microstructure, microhardness, porosity, bonding strength, impact toughness, and wear resistance of the CoNiCrAlY/Cr
2
O
3
·5SiO
2
·3TiO
2
coating were characterized and analyzed, and the wear mechanism of the ceramic coating was also analyzed. The results show that the average porosity of the coating is about 0.52%, the average microhardness is about 1 334.6 HV
0.2
, the average bonding strength is 61.7 MPa, and the friction and wear resistance is about 87.4 times that of the base 45
#
steel. The Cr
2
O
3
·5SiO
2
·3TiO
2
coating has excellent anti-wear properties. The wear mechanism of Cr
2
O
3
·5SiO
2
·3TiO
2
coating is abrasive wear, fracture and peeling. The CoNiCrAlY/Cr
2
O
3
·5SiO
2
·3TiO
2
coating has achieved good application effects on the piston rod of the gate hoist of Cao’e River.
2021 Vol. 26 (5): 436-441 [
Abstract
] (
251
)
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491
)
442
Effect of surface modifier on the rheological properties of Mg
2
TiO
4
microwave ceramics injection molding feedstock
SHI Yuan, LIU Shaojun
Mg
2
TiO
4
powders were modified by surfactants of stearic acid (SA), oleic acid (OA), 3-glycidyloxy- propyltrimethoxysilane (KH560) and 3-methacrylate-propyltrimethoxysilane (KH570). The effects of surfactants on the particle size distribution of Mg
2
TiO
4
powders and its mechanism were characterized by infrared analysis and particle size measurement. The Mg
2
TiO
4
powders before and after modification were used to prepared feedstocks with 44% solid load (volunm fraction). The effects of surfactants on the rheological properties, theoretical maximum loading capacity
φ
max
, activation energy and yield stress of feedstock were studied. The results show that the surfactants are chemisorbed on Mg
2
TiO
4
powder, which effectively reduce powder agglomeration. The OA can significantly reduce the viscosity and rheological activation energy of feedstock. The viscosity decreases from 39.55 Pa·s to 5.43 Pa·s (100 s
-1
); the activation energy decreases from 62 kJ/mol to 38 kJ/mol (100 s
-1
). The lowest yield stress of 12 Pa is obtained at 170 ℃ (1 832 kPa before modification). The maximum solid loading modified with KH560 is 135%.
2021 Vol. 26 (5): 442-450 [
Abstract
] (
296
)
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684
)
451
Properties of polyimide/sericite composite adhesive prepared by polyamic acid salt method
XIANG Yu, LANG Feng, WEI Mengling, LI Duxin
In order to obtain polyimide (PI) adhesives with stable properties, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 2,2'-bis[4-(4-Aminophenoxy)phenyl]propane (BAPP) and 4,4'-diaminodiphenylmethane (MDA) ternary monomers were co-condensed into polyimide based on the addition of triethylamine (TEA) synthesize the precursor of polyamic acid salt (PAAS) and modify it with organic sericite to obtain PI/sericite composite adhesive. The adhesive was analyzed by DSC, and the bond strength and dynamic mechanical properties were also tested. The results show that compared with pure PI adhesive, the storage stability, thermal stability, bonding strength and damping performance of PI/sericite composite adhesive are significantly improved. During DSC analysis, the temperature at (
T
5
) 5% mass loss and the temperature at (
T
10
) 10% mass loss of composite binder (mass fraction of sericite is 30%) are 25 ℃ and 21 ℃ higher than those of PI binder, respectively, and the bonding strength is up to 20.0 MPa, 29.7% higher than that of pure PI binder.
2021 Vol. 26 (5): 451-455 [
Abstract
] (
380
)
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1363
)
456
Effects of titanium transition layer on interface characteristics and mechanical properties of Al/steel explosive composites
ZHANG Wending, LI Huizhong, LIANG Xiaopeng, ZENG Zhiheng
The Al/Ti/steel (1060/TA1/Q235B) three-layer explosive composite plate was prepared by explosive composite technology with Ti transition layer. The interface characteristics of these composite plates were characterized and the mechanical properties were tested. The results show that the Al/Ti interface in the Al/Ti/steel composite plate is sinusoidal waveform, the Ti/steel interface is sawtooth waveform, and the interface is well bonded. Vortex melting zone is formed between Al/Ti and Ti/steel interface, and there is no brittle intermetallic compound region. The thickness of thermal diffusion layer of Al and Fe in titanium layer is 3 μm and 3.2 μm, respectively, which is 76.5% and 77.8% higher than that of Al/steel interface, respectively. The addition of Ti transition layer increases the bonding strength of Al/steel composite plate from 149.88 MPa to 178.22 MPa, and the interface shear strength from 75.20 MPa of Al/steel interface to 95.55 MPa of Al/Ti interface and 332.65 MPa of Ti/steel interface.
2021 Vol. 26 (5): 456-464 [
Abstract
] (
342
)
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(884 KB) (
795
)
465
Modification of sulfur cathode by CeO
2
-C composite hollow spheres and research on electrochemical performance
LI Neng, QIN Bihui, HUANG Suping, XIAO Qi
CeO
2
-C composite hollow spheres materials were synthesized by solvent-free template method using 3-aminophenol formaldehyde (APF) resin spheres and cerium nitrate hexahydrate (Ce (NO
3
)
3
·6H
2
O) as raw materials. The as-prepared samples were characterized by X-raydiffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier infrared spectroscopy (FTIR), etc. In addition, commercial conductive carbon black was used as the sulfur host material, and the prepared CeO
2
-C composite hollow spheres were used as an additive to modify the sulfur cathode material. The electrochemical performance of the modified sulfur cathode material was tested by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance (EIS), etc. The results show that the sulfur cathodes modified by CeO
2
-C composite hollow spheres exhibit higher initial discharge capacity of 1 125 mAh/g at 0.2 C, and the lower capacity decay rate of 0.083% per cycle at 1 C after 500 cycles. Using commercial conductive carbon black as sulfur carrier and adding a small amount of CeO
2
-Ccomposite hollow sphere modifier to prepare sulfur cathode can effectively improve the electrochemical performance of lithium sulfur battery without changing the current preparation process of lithium sulfur battery, showing great application potential.
2021 Vol. 26 (5): 465-474 [
Abstract
] (
328
)
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751
)
475
Inflammatory response of strontium titanate micro/nanoparticles in vitro
LIU Wentao, WU Hong, ZHOU Jixiang
The biological response of RAW 264.7 cells stimulated by strontium titanate micro/nanoparticles was studied by the direct interaction between cells and materials. Scanning electron microscope (SEM), laser particle size analyzer, X-ray diffractometer and specific surface area tester were used to characterize the physical and chemical properties of the materials. The effects of strontium titanate micro/nanoparticles on the proliferation activity of RAW 264.7 cells were evaluated by CCK-8 test and live/dead cell staining; the morphological changes of cells were observed by SEM; The expression of inflammatory cytokine genes in RAW 264.7 cells stimulated by strontium acid micro/nanoparticles. The results show that the compositions of the micron and nano strontium titanate particles are uniform and both have irregular shapes. The average particle size of the micron strontium titanate particles is 1 085.0 nm, the specific surface area is 1.72 m
2
/g, and the particle size of the nano strontium titanate particles is 505.2 nm. The specific surface area is 2.94 m
2
/g. The micron and nano strontium titanate particles have no effect on the proliferation activity of RAW 264.7 cells on the 24h and 72h. Under the stimulation of micro/nano strontium titanate particles, the RAW 264.7 cell morphology develops into a polygonal shape and has a larger attachment area. Micron strontium titanate particles stimulated high expression of inducible nitric oxide synthase (iNOS), cluster of differentiation (CD) 86, TNF-α and interleukin (IL)-6 genes in RAW 264.7 cells, and the expression of iNOS, tumor necrosis factor (TNF)-α and IL-6 genes is significantly higher than that of nano strontium titanate particles. nano strontium titanate particles stimulated RAW 264.7 cells to highly express iNOS and TNF-α genes, while IL-10 gene expression is significantly down-regulated. Both micron and nano strontium titanate particles stimulate RAW 264.7 cells to highly express iNOS, induce RAW 264.7 cells to polarize to the M1 phenotype, and produce an inflammatory response. The inflammatory response induced by micron strontium titanate particles is more significant.
2021 Vol. 26 (5): 475-482 [
Abstract
] (
303
)
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561
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