Amorphous GeO
2
@C anode materials were successfully prepared from commercial GeO
2
and C
6
H
12
O
6
.H
2
O by a hydrothermal method combined with sintering under nitrogen atmosphere protection. The ...anode materials showed an ideal spherical shape of about 3 μm and their surface was uniformly covered with C. GeO
2
@C composite anodes exhibited better storage performance for Li-ion batteries. The discharge-specific capacities of GeO
2
@C-3 sample were 1143, 1049, 776, 551, and 308 mAh g
-1
at current densities of 0.2, 0.5, 1, 2, and 5 A g
-1
, and restored to 1136 mAh g
-1
when the current density returned to 0.2 A g
-1
. The reversible specific capacity was 756 mAhg
-1
after 1000 cycles at a current density of 1 A g
-1
. The GeO
2
@C anode was stable in the process of charge and discharge, and no obvious pulverization occurred. GeO
2
@C composites stabilized the electrochemical properties through carbon and amorphous structure to improve the overall electrical conductivity in Li
+
embedding/de-embedding processes.
Due to their excellent high-temperature properties, iridium-rhodium (Ir–Rh) alloys have become candidate materials in the aerospace industry. Increasing Rh content significantly improves oxidation ...resistance, but the processing performance is dramatically impaired. Doping with Zr is an effective means of toughening Ir–Rh alloys and enhancing their high-temperature properties. However, Zr and Ir–Rh system alloys form infinite solid solution alloys, and observing their microstructures and understanding their mechanism of action through conventional experiments are difficult. Therefore, in this study, the stability and the mechanical and thermal properties of Ir-40Rh-MZr (
M
= 0, 0.5, 1.0, 3.0) alloys have been assessed by first-principles calculations based on density functional theory. The results showed that the elastic modulus of Ir-40Rh-Zr alloys reached a minimum value for Ir-40Rh-3.0Zr and that the trend was consistent with the strain energy per unit length of the alloy (the strain energy of Ir-40Rh-3.0Zr reached a minimum value of 1.95 Jm
−1
), suggesting that 3.0 wt.% Zr could effectively improve the plasticity of the alloy. Meanwhile, the fracture resistance of the alloy under high pressure was improved by doping with Zr, reaching 577.1 GPa at 1800 K for Ir-40Rh-3.0Zr. The coefficient of thermal expansion of Ir-40Rh-MZr at high temperatures was decreased with increasing Zr doping content. Evidently, the high-temperature resistance and thermal shock fracture resistance of the material were improved by the addition of Zr. Moreover, analysis of the electronic density of states indicated that the main reason for the improved machining performance on adding 3.0 wt.% Zr was the generation of a significant pseudo-energy gap. Our results implied that adding 3.0 wt.% Zr had the best effect on toughening and improving and high-temperature properties of Ir-40Rh alloy. This study should provide theoretical guidance for the further application of Ir–Rh alloys in the aerospace field.
The cast Al4·4Cu0·6Mn alloy samples were subjected to quenching at 530 °C for 14 h, followed by aging treatment at 170 °C for 6, 8, 10, and 12 h. The effects of aging treatment time on the mechanical ...properties including the tensile strength (σb), yield strength (σ0.2), elongation (δ5), hardness (HB), and microstructure morphology of the alloy were investigated using metallographic microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, tensile-property, and hardness tests. The highest tensile strength of the alloy was 481.4 MPa when the aging time was 8 h. The size of precipitates increased gradually with the increase in aging time, and their morphology developed gradually from granular and bundle to reticulation. The main strengthening phases of the alloy were the θ- and T-phases as determined by X-ray diffraction and energy dispersive spectroscopy. Dimples and tear ridges were observed in the fracture morphology of four samples after different aging times, indicating that the fracture mode for the studied alloy is quasi-cleavage fracture. The T-phase has better thermal stability. Therefore, the mechanical properties of the alloy under the heat treatment conditions in this paper were stable and were not significantly affected by the aging time.
We propose a new two-dimensional metallic carbon allotrope named QHOD-net using first-principles calculations, the structure of which includes five carbon rings; quadrangular, pentagonal, hexagonal, ...octagonal, and decagonal. This metastable phase metallic carbon material displays anisotropic mechanical properties, and its smallest and largest in-plane stiffness have been calculated to be
C
a
= 261 GPa nm and
C
b
= 240 GPa nm, respectively, both much lower than for graphene. The Poisson's ratio is as low as 0.29, which has good toughness. The DFT indicates that QHOD-net is metallic with no bandgap in the entire BZ region and one band crosses the Fermi level. At the Fermi level, the electron density of states per atom is much higher, reaching ~ 0.297 eV/states/per atom. In addition, we have performed the 3D stacked structure of the two-dimensional structure QHOD-net, and the results of our study indicate that the stacked structure is a super-hard 3D carbon material (74.8 GPa nm). The two-dimensional structure QHOD-net contains a large number of tetragonal, pentagonal, octagonal, and decagonal carbon rings than the perfect hexagonal shape of ideal graphene. The disorder of the material is increased compared to that of graphene. It is this disorder that triggers these interesting findings, and in addition we provide a new strategy for the design of 2D structures with multiple carbon rings.
In this study, secondary ion mass spectrometry and a semiconductor parameter analyzer were used to study and analyze the component interdiffusion at the CdTe/HgCdTe interface before and after ...annealing, as well as the effect of the formation of a gradient bandgap layer from annealing on the electrical properties of the metal–insulator-semiconductor (MIS) structure. The site-direction relationship of the contracted crystals at the CdTe/HgCdTe interface was revealed by transmission electron microscopy, and it was found that the stacking dislocations in the CdTe layer were significantly reduced after annealing and that the Hg atoms diffused into the CdTe layer through the high-temperature annealing and occupied the lattice positions of the Cd atoms, thus forming the HgCdTe structure, which formed a contracted-crystalline structure with the CdTe substrate. Molecular dynamics was applied to simulate the specific atomic diffusion behavior at different temperatures and different times during the high temperature annealing process, and the above experimental results were verified by a research note on the variation of the diffusion phenomena during the process.
An environment-friendly solvent debinding process for polyoxymethylene (POM) for metal injection molding (MIM) is presented as an alternative to the traditional catalytic debinding method. This study ...investigated the influence of various acid solvents and debinding temperature. The optimal debinding parameters were 5 M nitric acid solution at 60 °C. Based on the calculation of effective diffusivity and activation energy, the solvent-debinding mechanism for POM is proposed. The removal of POM was controlled by three processes: dissolution, diffusion, and chemical reaction. The resulting final titanium parts have a high density of over 95% and an ultimate tensile strength of 406 MPa.
Ir doping is an effective method used to strengthen and toughen Pt–Rh alloy and improve its high-temperature properties. However, Ir and Pt–Rh alloys are infinite solid solution alloys, and their ...microstructures are difficult to observe to understand their mechanism of action. Therefore, the stability and mechanical and thermal properties of a series of Pt–20Rh–xIr (
x
= 0, 5, 10 and 20) alloys were calculated using first-principle studies based on density functional theory. The results show that with an increase in the Ir content, the Young’s modulus and hardness of Pt–20Rh–xIr initially decrease and then increase. The largest Young’s modulus (436.243 GPa) and hardness (18.453 GPa) were achieved when the Ir content was 20 wt%. Meanwhile, the thermodynamic calculation results show that with an increase in the Ir content, the thermal stability of Pt–20Rh–xIr was significantly improved, and the thermal expansion coefficient of Pt–20Rh–xIr was only 63% of that observed for Pt–20Rh. The above results imply that the addition of 20 wt% Ir gave the best effect on improving the strength, toughness and high temperature properties of Pt–20Rh alloy. This study provides theoretical guidance for further application of Pt–Rh alloy in the aviation field.
This present work aims to understand the strengthening mechanism of TiB2p reinforced rheological forming of Al matrix composites. The mechanism of in-situ TiB2p on microstructure evolution and ...mechanical properties strengthening of semi-solid Al–20Si (wt%) alloy was studied. The experiments show that the primary Si phase, α-Al phase, and eutectic Si are refined by in-situ TiB2p combined semi-solid forming. The primary Si phase is distributed uniformly in the matrix and the morphology of eutectic Si phase changed from needle-like to short rod-like. In addition, the Si/TiB2p interface is clear and well-bonded but no orientation relationship existed. On the contrary, the TiB2 are tightly bound to the α-Al and exist good lattice matching coherence in (01-1-1)TiB2p//(200)α-Al. The tensile strength and elongation are an increase from 110 MPa to 2.3% to 215.7 MPa and 4.2% with the content of in-situ TiB2p from 0 to 6%, respectively, own to dislocation strengthening, fine grain strengthening, and second phase grain strengthening induced by TiB2p. The fracture form from cleavage fracture to cleavage-ductile mixed-mode fracture due to the incorporation of TiB2p inhibits the crack propagation.
Protein tyrosine phosphatase non-receptor type 12 (PTPN12) is a recently identified tumor suppressor gene (TSG) that is frequently compromised in human triple-negative breast cancer. In the present ...study, we investigated the expression of PTPN12 protein by patients with breast cancer in a Chinese population and the relationship between PTPN12 expression levels and patient clinicopathological features and prognosis. Additionally, we explored the underlying down-regulation mechanism from the perspective of an epigenetic alteration. We examined PTPN12 mRNA expression in five breast cancer cell lines using semi-quantitative reverse-transcription PCR, and detected PTPN12 protein expression using immunohistochemistry in 150 primary invasive breast cancer cases and paired adjacent non-tumor tissues. Methylation-specific PCR was performed to analyze the promoter CpG island methylation status of PTPN12. PTPN12 was significantly down-regulated in breast cancer cases (48/150) compared to adjacent noncancerous tissues (17/150; P < 0.05). Furthermore, low expression of PTPN12 showed a significant positive correlation with tumor size (P = 0.047), lymph node metastasis (P = 0.001), distant metastasis (P = 0.009), histological grade (P = 0.012), and survival time (P = 0.019). Additionally, promoter CpG island hypermethylation occurs more frequently in breast cancer cases and breast cancer cell lines with low PTPN12 expression. Our findings suggest that PTPN12 is potentially a methylation-silenced TSG for breast cancer that may play an important role in breast carcinogenesis and could potentially serve as an independent prognostic factor for invasive breast cancer patients.
This study aims to achieve synergistic strength-ductility enhancement of semi-solid squeeze cast 6TiB2/Al–17Si–4Cu composites through in-situ particle strengthening and T6 heat treatment. The ...microstructure and mechanical properties of 6TiB2/Al–17Si–4Cu composites with different heat treatments were investigated. TiB2 particles are semi-coherent with α-Al and primary Si, respectively. The nanoscale precipitate phases were determined by their crystal orientation relationships. The results showed that they are θ and θʹ phases. Meanwhile, the research results pertaining to the mechanical properties imply that the strength and ductility are enhanced by the TiB2 particles and Al2Cu precipitates. The optimum heat treatment process (solution treatment for 9 h at 520 °C and aging for 8 h at 170 °C) of strengthened 6TiB2/Al–17Si–4Cu composites is revealed in this study, when the ultimate tensile strength and elongation of the composites are 263.3 MPa and 0.51%, respectively. The mechanisms governing the enhanced strength and ductility of 6TiB2/Al–17Si–4Cu composites were discussed.
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