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2023 Vol. 28, No. 1
Published: 2023-02-15
Engineering and Technology
Theoretical Research
Theoretical Research
1
Numerical simulation of integrated inductor process by liquid composites molding
WANG Hao, GUO Feng, FU Bangliang, YAN Liangming
DOI: 10.19976/j.cnki.43-1448/TF.2022065
When the traditional molding method is used to prepare the integrated forming inductance, the forming pressure is large, and the formed inductance is prone to short circuit, sudden change of insulation impedance, coating cracking and peeling. In this paper, a new inductance molding method, liquid composites molding, was proposed. The whole process of inductive molding was simulated and analyzed by finite element software. The effects of mold temperature and filling time on the curing degree, as well as the effects of filling speed on the filling time and pore size were studied, so as to obtain the optimized forming process parameters. Then, an inductance molding experiment is conducted to test the inductance value (
L
), direct current resistance (DCR) and full load resistance (FLL). The results show that the curing degree increases with the increase of mold temperature or curing time. With the increase of filling speed, the filling time is shortened, and the number and size of pores first decrease and then increase. The optimum process parameters are mold temperature 175 ℃, filling speed 3 mm/s and curing time 150s. The inductance (FeSiAl/epoxy resin) has an average inductive value of 46.58 μH. The DCR is 116 mΩ, and the inductive value drop rate is 33.25% under 2.6 A for 30 min. The key indicators of the inductance are better than those of inductance prepared by traditional molding process. It proves that the liquid
2023 Vol. 28 (1): 1-8 [
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1000
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Engineering and Technology
9
Electrochemical properties of copper doped honeycomb-layered Na
3
Ni
2
SbO
6
cathode materials
CHEN Lin, HUANG Qun, CHEN Cheng, FENG Yiming, WEI Weifeng
DOI: 10.19976/j.cnki.43-1448/TF.2022089
Honeycomb layered Na
3
Ni
2
SbO
6
cathode materials were doped with Cu instead of Ni to obtain Na
3
Ni
2-
x
Cu
x
SbO
6
(
x
=0, 0.2, 0.4, 0.8) cathode materials. The morphology, structure and electrochemical properties of the materials were investigated by X-ray diffract to meter and scanning electron microscope. The results show that the cycling stability of Na
3
Ni
2
SbO
6
cathode materials can be greatly enhanced by Cu substitution, i.e. the Cu-doped Na
3
Ni
1.8
Cu
0.2
SbO
6
materials display a discharge capacity of 72.3 mA∙h/g after cycled for 100 cycles at 0.1C rate, while the discharge capacity of pristine Na
3
Ni
2
SbO
6
cathode is only 39.5 mA∙h/g under the same situation. Through theoretical calculation and experimental analysis, it is found out that the introduction of Cu (Ⅱ) can effectively reduce the band gap of Na
3
Ni
2
SbO
6
layered cathode materials and the diffusion energy barrier of Na
+
, and improve the electronic conductivity and ion diffusion performance of the cathode materials, and Cu substitution can also inhibit the adverse phase change of Na
3
Ni
2
SbO
6
cathode materials during the cycle, thus improving the cycle stability and electrochemical performance of the layered cathode materials.
2023 Vol. 28 (1): 9-11 [
Abstract
] (
490
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20
Construction and application of model of W@Cu core-shell powder prepared by intermittent electrodeposition technology based on machine learning
DENG Nan, LIANG Shuhua, LI Jianqiang
DOI: 10.19976/j.cnki.43-1448/TF.2022066
The uniform distribution of W and Cu phases is very important for obtaining high performance W-Cu composites. This paper mainly studies the construction and application of the model of W@Cu core-shell powder prepared by intermittent electrodeposition based on machine learning. Firstly, a machine learning model for the preparation of W@Cu core-shell powder by intermittent electrodeposition was established, and the relationships between the theoretical core-shell powder coating thickness and current, electrodeposition time, particle size of the powder to be plated, and the load capacity were determined. Further, the experimental verification was carried out
2023 Vol. 28 (1): 20-27 [
Abstract
] (
462
)
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28
Effect of Al
2
O
3
addition on microwave dielectric properties of Li
2
ZnTi
3
O
8
ceramics
DONG Qingchen, LIU Kunlei, YU Shihui, LIU Xiansheng, ZHANG Weifeng
DOI: 10.19976/j.cnki.43-1448/TF.2022072
Li
2
ZnTi
3
O
8
was synthesized by solid-state reaction. The microwave dielectric ceramics composed of Li
2
ZnTi
3
O
8
and Al
2
O
3
were prepared (The Al
2
O
3
mass is 0-7% of Li
2
ZnTi
3
O
8
mass). The effects of Al
2
O
3
addition amount on the microstructures and dielectric properties of the samples were investigated. The results show that the primary phase of the composite ceramics is cubic structure Li
2
ZnTi
3
O
8
. ZnAl
2
O
4
and TiO
2
phases are observed with the increase of Al
2
O
3
addition amount, which have a great influence on the microwave dielectric properties of the ceramic samples. The addition of Al
2
O
3
can inhibit the growth of Li
2
ZnTi
3
O
8
grains. When the sintering temperature is 1 100 ℃ and the Al
2
O
3
addition is 1%, the microwave dielectric ceramics composed of Li
2
ZnTi
3
O
8
and Al
2
O
3
obtain the best dielectric properties:
ε
r
≈ 26.1,
Q×f
≈ 87 900 GHz,
τ
f
≈13.3
×
10
-6
℃
-1
.
2023 Vol. 28 (1): 28-34 [
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396
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35
Effects of hard particles on microstructure and wear-resistance of plasma cladding WC/multi-principal components alloy composite hard facing coating
YANG Zihan, LIU Yong, ZHANG Wei, LIU Bin
DOI: 10.19976/j.cnki.43-1448/TF.2022086
Two kinds of hardfacing composite coatings with cast WC particles and sintered WC-Co particles as hard particles and multi principal alloy as bonding phase were prepared by plasma cladding technology. The effects of different hard particles on the microstructure and wear resistance of the hardfacing composite coating were studied by means of X-ray diffraction, scanning electron microscopy and friction experiments. The results show that the volume fraction content of M
6
C in FeCrNi/WC-Co composite coating (20.1%) is lower than that in FeCrNi/WC composite coating (28.4%). The sintered WC-Co particles have high thermodynamic stability, and the dissolution of WC is lower than that of cast WC particles, which can effectively reduce the precipitation of brittle M
6
C carbides. The wear resistance of FeCrNi/WC-Co composite coating is better than that of FeCrNi/WC coating. FeCrNi/WC-Co coating with less M
6
C phases can avoid premature peeling of the coating due to brittle fracture, ensure the integrity of hard phase particles, and improve the wear resistance of the hardfacing coating.
2023 Vol. 28 (1): 35-43 [
Abstract
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387
)
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1224
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44
Effects of SiO
2
and ZrO
2
on friction and wear properties of copper-based friction materials mated with C/C-SiC composites
LI Chenxin, LIU Rutie, LIN Xueyang, CHEN Jie, XIONG Xiang, LIAO Ning
DOI: 10.19976/j.cnki.43-1448/TF.2022087
SiO
2
and ZrO
2
were added to powder metallurgy Cu-based friction materials respectively. The effects of SiO
2
and ZrO
2
on the friction and wear properties of powder metallurgy Cu-based friction materials mated with C/C-SiC composites were studied, and the internal relationship between their influence mechanisms was analyzed. The results show that the Cu-based friction materials containing SiO
2
or ZrO
2
can achieve high average friction coefficient (0.375 8 and 0.342 4 respectively) at high braking speeds when they is mated with C/C-SiC composites. The wear of the friction materials are very low, which is 1.44 μm/time and 0.95 μm/time respectively, and the C/C-SiC composites has almost no wear. During the braking process, SiO
2
is easy to fall off and form abrasive particles, causing abrasive wear on the two friction surfaces. However, ZrO
2
remains intact in the matrix, which mainly ploughs the friction surface of C/C-SiC composites in the form of hard micro bumps. SiO
2
is easily embedded in the friction film of C/C-SiC composites after breaking and falling off at high braking speed, which is conducive to the accumulation of wear debris mainly composed of Cu and Cu compounds around it, and promotes the formation of friction transfer film on the friction surface of C/C-SiC composites to improve the friction and wear properties of the materials.
2023 Vol. 28 (1): 44-54 [
Abstract
] (
402
)
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(1005 KB) (
843
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55
Effects of Cr
3
C
2
content on microstructure and mechanical properties of hot-pressed sintered WC based cemented carbides
YUAN Yulan, LIU Hanlian, HUANG Chuanzhen, LIU Yang, WANG Limei, JI Lianggang
DOI: 10.19976/j.cnki.43-1448/TF.2022078
In order to develop cemented carbide tool materials with high strength and high hardness, WC-based cemented carbides with different Cr
3
C
2
contents were prepared by vacuum hot-pressed sintering technology. The phase compositions and microstructures of the WC-based cemented carbides were studied by XRD, SEM, and EDS. The effect of Cr
3
C
2
content on the mechanical properties and microstructures of WC-based cemented carbide were investigated as well. The results show that appropriate amount of Cr
3
C
2
can effectively inhibit the abnormal growth of WC grains, improve grain uniformity, reduce microstructure defects, and improve its comprehensive mechanical properties. With the increase of Cr
3
C
2
content, the hardness and bending strength of the alloys increase firstly and then decrease, and the fracture toughness first decreases and then increases. When the mass fraction of Cr
3
C
2
is 0.4%, the WC based cemented carbide has the best comprehensive mechanical properties, with the hardness (HV) of
2023 Vol. 28 (1): 55-62 [
Abstract
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402
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628
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63
Construction and properties of microporous layer with gradient pore structure
LIU Zhipeng, LI Li, WU Xiaobo, XIE Zhiyong, LEI Ting
DOI: 10.19976/j.cnki.43-1448/TF.2022080
As one of the key components of PEMFC (polymer electrolyte membrane fuel cell), the GDL (gas diffusion layer) plays a crucial role in the water management of the battery, The microporous layers with different gradient pore structures were constructed on the carbon paper substrate using conductive nano carbon black, MWCNTs and graphite sheets as microporous carbon materials. Scanning electron microscope and mercury injection instrument were used to measure the micropore morphology and pore structure of the all microporous layers. Then the resistivity, gas permeability and breakthrough pressure of the diffusion layers were also tested. Finally, the output performance of a single cell was studied by a fuel cell test platform. The results show that the gradient pore structure porous layer is formed due to the “double peak” distribution of MWCNTs layer and graphite sheet layer, which promotes the separation of gas-liquid two-phase transport and improves the battery's mass transfer capacity. Compared with the double-layer design, the three-layer gradient pore structure microporous layer has better performance. When the current density reaches 5.5 A/cm
2
, there is no obvious mass transfer polarization of the diffusion layer, and its maximum power is 1 855 mW/cm
2
. Compared with the commercial GDL, it is increased by 21%.
2023 Vol. 28 (1): 63-73 [
Abstract
] (
401
)
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532
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74
Fabrication of Cu-Al
2
O
3
composite powder by spray drying and its microstructure, properties
WU Hao, GAN Xueping
DOI: 10.19976/j.cnki.43-1448/TF.2023003
Aluminum nitrate and copper nitrate were used to prepare Cu-Al
2
O
3
composite powders by spray drying, roasting, reduction and ball milling. Cu-Al
2
O
3
composites were prepared by hot pressing sintering, eventually the further densification of the materials were achieved by hot forging. The microstructure and morphology of the Cu-Al
2
O
3
composite powders and bulk materials were studied by X-ray diffraction scanning electron microscopy and transmission electron microscopy, the tensile strength and conductivity of the composite materials were also tested. The results indicate that the Cu-Al
2
O
3
composite powders are flake and the distribution of Al
2
O
3
is uniform. The sintered composites have a low density of 95.4%, the tensile strength and conductivity are only 306 MPa and 89.4%IACS. After hot forging, the density increases to 99.9%, the tensile strength and conductivity increase to 422 MPa and 94.8%IACS. γ-Al
2
O
3
particles are uniformly distributed in the copper matrix: large-sized particles (50?100 nm) exist at grain boundaries and small-sized particles (10?20 nm) precipitates within grain boundaries.
2023 Vol. 28 (1): 74-82 [
Abstract
] (
450
)
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(1065 KB) (
797
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83
Effect of silicon-doped amorphous carbon films on the tribologicalproperty of TC4
WANG Ling, TAN Zhoujian, CAI Zhixia, LUO Ye, ZHANG Fuqin, ZHANG Xiang
DOI: 10.19976/j.cnki.43-1448/TF.2022095
Diamond-like layers and Si-DLC layers with different Si contents on the surface of Ti-6Al-4V (TC4) alloys were fabricated by plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering using C
2
H
2
and Si targets. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) measurement were used to analyze the bonding content and structural disorder of different films. The mechanical properties of the TC4 alloy and the films deposited were measured by the method of nanoindentation and nano-scratch. The HT-1000 high-temperature friction and wear tester and optical profiler were used to measure the frictional wear properties. The results show that regardless of whether there is Si element in the DLC layer, the surface hardness of TC4 substrate can be effectively improved. The hardness of the pure DLC film layer is 2.4 times higher than that of the uncoated TC4, and the improvement rate is the largest among the four films. Pure DLC and two kinds of Si-DLC films with mole fractions of Si of 1.79% and 3.06% respectively, all can reduce the surface friction coefficient of TC4 substrate from 0.64 without coating to about 0.1 and the wear rate is also reduced from 476.5×10
-7
mm
3
/(N·m) to about 0.5×10
-7
mm
3
/(N·m), indicating that three kinds of coatings are helpful to improve the wear resistance of the TC4 substrate surface.
2023 Vol. 28 (1): 83-92 [
Abstract
] (
360
)
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