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Heterostructure engineering is crucial for enhancing gas sensing performance. However, achieving rapid response for room-temperature NO2 sensing through rational heterostructure design remains a challenge. In this study, a Bi2Se3/SnSe22D/2D heterostructure was synthesized by hydrothermal method for the rapid detection of NO2 at room temperature. By combining Bi2Se3 nanosheets with SnSe2 nanosheets, the Bi2Se3/SnSe2 sensor demonstrated and the lowest detection limit for NO2 a short response time (15 s) to 10 ppm NO2 at room temperature, reaches 25 ppb. Furthermore the sensor demonstrates significantly larger response to NO2 than to other interfering gases, including 10 ppm NO2, H2S, NH3, CH4, CO, and SO2,demonstrating its outstanding selectivity. And we discuss the mechanism of related performance enhancement. [ABSTRACT FROM AUTHOR]

Al2O3 dispersion-strengthened (ODS) copper has an excellent comprehensive performance due to the strong hindrance of the high concentration nano-Al2O3 to the dislocations inside copper grains. However, the processability of ODS copper is seriously deteriorated, which is caused by the presence of unfavorable microlevel Al2O3 particles along powder particle boundaries. In this study, a strategy of ball-milling-induced impurity removal is adopted to surmount the dilemma. It was found that the ball milling process can significantly weaken the formation of large Al2O3 particles in the primary boundaries. However, due to the activation of the powder particle surface, the metallurgical bonding between the powder particles is strengthened. The results showed that the ball-milled samples exhibited the optimal properties, including the ultimate tensile strength of 488 ± 3 MPa, elongation of 18.7 ± 0.7%, reduction in the area of 46.8 ± 1.2%, 82.2 ± 0.3 Rockwell Hardness measured on the B scale (HRB), and electrical conductivity of 77.2 ± 0.1% International Association of Classification Societies (IACS).

Powder metallurgy (PM) offers cost-effective potential for manufacturing titanium and titanium alloys. High oxygen content on titanium powder surface is a key problem affecting the mechanical properties of PM Ti alloys. Therefore, this study proposes a chloro-deoxidation method to reduce the oxygen content of titanium powder via introducing stannous chloride (SnCl2) into titanium powder. In the sintering process, SnCl2 reacts with the surface oxide on titanium powder to remove the oxide film, and thus forms gas TiClxOy escaping from Ti matrix, resulting in the decrease of oxygen content. With ~ 2.5 wt.% SnCl2 addition, the oxygen content reduces from 0.6 wt.% to 0.5 wt.%. Accordingly, the elongation of as-sintered Ti-SnCl2 sample significantly increases from 4.8% to 11% (increasing by 129%), while the tensile strength decreases from 815 MPa to 788 MPa. After HIP treatment, the elongation increases from 11% to 13%, and the strength is about 765 MPa. Although same Sn content (5 wt.%) is added in Ti samples, Ti-SnCl2 sample shows higher elongation value of 9.4% compared to Ti-Sn sample (3.6%), due to lower oxygen content. [ABSTRACT FROM AUTHOR]

This study provides an effective surface modification method for Li-rich layered oxide (LLO, Li1.2Mn0.54Ni0.13Co0.13O2) with Al2O3 coating. Strong organic acid TFBDC (2,3,5,6-tetrafluoro-1,4-phthalic acid) accumulates near alkali metal oxide LLO to form uniform Al-TFBDC coating. Al-TFBDC modified LLO is subjected to heat treatment to form Al2O3 coating on the surface of LLO. This uniform coating protects LLO from direct contact with electrolyte and does not block the migration of Li+. Meanwhile, F− is successfully doped into LLO particles. The LLO coated with doping has clear layer structures, and its electrochemical properties have been significantly improved. The rate performance is increased by 66% at 10 C. After 150 cycles, its capacity retention rate is 92.5%, while that of uncoated LLO is only 55.8%. [ABSTRACT FROM AUTHOR]

A novel and quick process combining self-propagating reaction with vacuum-expendable pattern casting is presented to accomplish integrated preparation of millimeter-thick TiCp/Al composite coatings on the Al substrate. Titanium and graphite powders were mixed with the polytetrafluoroethylene (PTFE) additive and pasted on the expendable polystyrene (EPS) followed by compaction. Al components with in situ TiCp/Al composite coating were simultaneously synthesized at a relatively low temperature of molten Al, which was poured into the assembly of EPS and powder compact inside the silica sands. Differential scanning calorimetry, x-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy and transmission electron microscopy were used to systematically investigate the thermodynamic characteristics of the reaction, the phase constituents, microstructure and tribological properties of the coatings. The infiltration model describing the densification of the reaction coatings was also developed for the critical wetting condition. The wear characteristics were assessed using a pin-on-disk tribometer with various loads. Results showed that uniform TiC particles stimulated by the PTFE-activated self-propagating reaction afforded superior mechanical properties and wear resistance. [ABSTRACT FROM AUTHOR]

Microstructure evolution and variations in mechanical properties of Al-Al2O3 nanocomposite produced by powder metallurgy were investigated and compared with commercially pure aluminum (Al-1050) after furnace annealing. Fine gas-atomized Al powder compacts were first sintered in flowing nitrogen, subsequently consolidated into wires by rotary swaging and eventually annealed at 300 and 500 °C for 24 h each. Scanning and transmission electron microscopy with energy-dispersive spectroscopy was utilized to document the microstructure evolution. Rotary swaging was proven to lead to a marked decrease in grain size. After heavy swaging to true deformation degree of φ = 6 and annealing at 500 °C, obvious recrystallization was observed at Al-1050’s existing grain boundaries and the crystals began to grow perpendicular to the flow direction. In the Al-Al2O3 nanocomposite, fabricated from d50 = 6 μm Al powder, recrystallization partially occurred, while grains were still extremely fine. Due to the dual role of fine-grained Al2O3 dispersion strengthening, the nanocomposite showed improved mechanical performance in terms of tensile strength, approximately twice higher than Al-1050 after annealing at 500 °C. [ABSTRACT FROM AUTHOR]

This study provides an effective surface modification method for Li-rich layered oxide (LLO, Li1.2Mn0.54Ni0.13Co0.13O2) with Al2O3 coating. Strong organic acid TFBDC (2,3,5,6-tetrafluoro-1,4-phthalic acid) accumulates near alkali metal oxide LLO to form uniform Al-TFBDC coating. Al-TFBDC modified LLO is subjected to heat treatment to form Al2O3 coating on the surface of LLO. This uniform coating protects LLO from direct contact with electrolyte and does not block the migration of Li+. Meanwhile, F− is successfully doped into LLO particles. The LLO coated with doping has clear layer structures, and its electrochemical properties have been significantly improved. The rate performance is increased by 66% at 10 C. After 150 cycles, its capacity retention rate is 92.5%, while that of uncoated LLO is only 55.8%. [ABSTRACT FROM AUTHOR]

Heterostructure engineering is crucial for enhancing gas sensing performance. However, achieving rapid response for room-temperature NO 2 sensing through rational heterostructure design remains a challenge. In this study, a Bi 2 Se 3 /SnSe 2 2D/2D heterostructure was synthesized by hydrothermal method for the rapid detection of NO 2 at room temperature. By combining Bi 2 Se 3 nanosheets with SnSe 2 nanosheets, the Bi 2 Se 3 /SnSe 2 sensor demonstrated and the lowest detection limit for NO 2 a short response time (15 s) to 10 ppm NO 2 at room temperature, reaches 25 ppb. Furthermore the sensor demonstrates significantly larger response to NO 2 than to other interfering gases, including 10 ppm NO 2 , H 2 S, NH 3 , CH 4 , CO, and SO 2 ,demonstrating its outstanding selectivity. And we discuss the mechanism of related performance enhancement., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Yi, Chen, Yu, Hao and Wang.)