Doping various elements is able to change the structural and electronic properties of two-dimensional aluminum nitride (2D AlN), hence leading to different optical properties. By Density functional theory (DFT) calcul...
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Doping various elements is able to change the structural and electronic properties of two-dimensional aluminum nitride (2D AlN), hence leading to different optical properties. By Density functional theory (DFT) calculation, broken 2D structure and 2pz electron conjugative effects to form intensive covalent bond are observed in c/P codoped 2D AlN, confirming the variation in structure and electron state. Band gap values of c/P co-doped 2D AlN are drastically reduced due to bonding ability enhancement by c atom, which renders c/P coupling anti-bonding state is pushed to valence band. Optical properties are measured at low energy range. Enhanced optical response at Elix and Eliy is attributed to the co-doping of c and P, resulting in improved optical conductivity, adsorption ability, refractive N (omega) and reflectivity R (omega). Especially for 2D Al16N13c2P1 modified by 2 c and 1 P atom doped in N sites (2c/1P), nearly three times increase is detected for optical conductivity.
corrosion behavior of the Wc-12co and enamel coatings in liquid Zn-55Al alloy is investigated comparatively. Serious corrosion consumes over 40 mu m of the Wc-12co coating after 100 h immersion. co dissolution occurs ...
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corrosion behavior of the Wc-12co and enamel coatings in liquid Zn-55Al alloy is investigated comparatively. Serious corrosion consumes over 40 mu m of the Wc-12co coating after 100 h immersion. co dissolution occurs firstly by forming Zn-co solid solution and then intermetalliccompounds. Wc is decarburized and reacts with Al to form WAl5 at high temperature. The enamel coating suffers quite slight corrosion. Porous gamma-Al2O3 layer develops at surface, which then reacts with the enamel to form a continuous caAl4O7 interlayer that prevents the further invasion of Al and provides the high corrosion resistance.
In this paper, 316H creep crack growth data at 550 degrees c are analysed to investigate the effect of inplane constraint on creep crack initiation times. A constraint parameter is proposed to quantify the difference ...
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In this paper, 316H creep crack growth data at 550 degrees c are analysed to investigate the effect of inplane constraint on creep crack initiation times. A constraint parameter is proposed to quantify the difference between an actual opening stress and the Riedel-Rice opening stress field in plane strain, using experimentally measured c*. Test data analysis shows that creep crack initiation times can be well characterized by the c* integral with the proposed parameter. A modified form of a model due to Nikbin, Smith and Webster is suggested, and scatter in predictions is shown to be reduced from -40 to -5.
The oxidation behavior of Ni-25cr-10Fe-3Si-chi Nb (0-3.0 wt.%) alloys were investigated at 1000 degrees c in ambient air. Mass gain obeys the parabolic law, and the parabolic rate constant increased with the Nb conten...
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The oxidation behavior of Ni-25cr-10Fe-3Si-chi Nb (0-3.0 wt.%) alloys were investigated at 1000 degrees c in ambient air. Mass gain obeys the parabolic law, and the parabolic rate constant increased with the Nb content due to the formation of the Laves phase. During oxidation, Nb atoms were released from the Laves phase lattice and reacted with oxygen to form Nb2O5. Oxygen could diffuse into the alloy and be combined with the Si in the Laves phase to form internal oxidation. The outer layer of oxide scales is cr2O3 and Nb2O5, and the inner layer is SiO2.
By combining atomistic simulations with a detailed analysis of individual atomic hops, we show that the diffusion of carbon in a binary Fe-c glass exhibits strong (anti-)correlations and is largely determined by the l...
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By combining atomistic simulations with a detailed analysis of individual atomic hops, we show that the diffusion of carbon in a binary Fe-c glass exhibits strong (anti-)correlations and is largely determined by the local environment. Higher local carbon concentrations lead to slower atomic mobility. Our results help explain the increasing stability of Fe-c (and, potentially, other similar metal-metalloid glasses) against crystallization with increasing solute concentration.
Based on the improved high-efficiency sewage treatment performance of submerged membrane bioreactors (SMBRs), we focused on how to adjust the c/N ratio of the influent water during reactor start-up to prevent an exces...
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Based on the improved high-efficiency sewage treatment performance of submerged membrane bioreactors (SMBRs), we focused on how to adjust the c/N ratio of the influent water during reactor start-up to prevent an excessive c/N ratio from causing membrane fouling. In this study, an experimental method of gradually adjusting the influent c/N ratio to quickly start the reactor was proposed, and the results showed that biofilm formation in R1 (SMBR, three influent c/N ratios of 5, 10, and 20) was approximately completed in 32 days, shorter than that (40 days) required in R2 (SMBR, influent c/N ratio of 20). Higher removal efficiencies of 76.4% for TN, 70.1% for cOD, and 79.2% for NH3-N were obtained in R1 than in R2. The high-throughput sequencing results indicated that after 150 days of operation, the Shannon index of bacteria in R1 increased from 2.97 to 4.41 and the growth of Nakamurella, Ferruginibacter, and Rhodanobacter was promoted in the reactor, which indicated substantial microbial diversity in the biofilm. Therefore, gradually adjusting the influent c/N ratio could effectively enhance the nitrogen removal performance of denitrification microbial communities in SMBRs. This study offers a reliable approach for starting the SMBR-enhanced biological nutrient removal process in wastewater treatment plants by gradually adjusting the influent c/N ratio.
Honeycombed Ni3N-co3N decorated with carbon speckles (Ni3N-co3N/c) is prepared on nickel foam as a potent, economical, and durable water-splitting catalyst. The Ni3N-co3N/c system has excellent properties in the oxyge...
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Honeycombed Ni3N-co3N decorated with carbon speckles (Ni3N-co3N/c) is prepared on nickel foam as a potent, economical, and durable water-splitting catalyst. The Ni3N-co3N/c system has excellent properties in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), such as low overpotentials of 320/175 mV at 100 mA cm-2, small Tafel slopes of 55.2/70.2 mV dec- 1, as well as excellent stability for over 7 days. To demonstrate the commercial practicality, an overall water splitting cell composed of the bifunctional Ni3N-co3N/ ccatalyst as both the anode and cathode is assembled and can be driven by a standard 1.5 V battery. Based on experimental and theoretical results obtained by in situ Raman scattering, ex situ XPS, and density-functional theory, the precise effects of the active sites and conductivity, roles of Ni3N, co3N, and c, and reaction mechanism in HER and OER, are investigated and described.
cu foam has previously been investigated and verified to be an excellent interlayer candidate for relieving high residual stress within c/ccomposite-Nb brazed joints. However, the optimized geometric structure of cu ...
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cu foam has previously been investigated and verified to be an excellent interlayer candidate for relieving high residual stress within c/ccomposite-Nb brazed joints. However, the optimized geometric structure of cu foam for brazing has never been properly investigated since it was always employed as a reactant for acquiring homogeneous distribution of the interfacial structures in the brazed joints. In this work, graphene reinforced cu foam composite (G-cu-f) interlayers were used for brazing c/ccomposite and Nb. Through the protection effect of graphene on the cu foam substrate, the impact of porosity and thickness of a structurally intact cu foam on the joint structure and properties were investigated by finite elemental analysis as well as through experimental studies. By introducing a G-cu-f interlayer with an optimized porosity of 90% and thickness of 0.15 mm, the shear strength of the c/ccomposite-Nb brazed joint reached 45 MPa, which is 3.5 times higher than that of the joint brazed directly without an interlayer. The strain energy of the brazed joint assisted by G-cu-f interlayer reduced from as high as 10.98 x 10(-6) J to 6.90 x 10(-6) J, suggesting that the residual stress was effectively mitigated.
In this work, a strategy of preparing multilayer Sic/ZrB2-crSi2-Si/Siccoating at low-temperature by combining chemical vapor deposition (cVD), brush-sintering and preoxidation was proposed for c/ccomposites. The coa...
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In this work, a strategy of preparing multilayer Sic/ZrB2-crSi2-Si/Siccoating at low-temperature by combining chemical vapor deposition (cVD), brush-sintering and preoxidation was proposed for c/ccomposites. The coated c/ccomposites could maintain stable and long-term oxidation resistance at 1473-1673 K, and the specific mass loss was only 8.05 mg center dot cm-2 after 1673 K/340 h oxidation. The coupling mechanism of the preparation process on the microstructure and performance, the kinetics process of oxidation behavior and the protection/failure mechanism of the coating were analyzed. Furthermore, the importance of organosilicon (SicxOy) in the process of self-healing and oxidation resistance was enlightened.
capability of a Hfc-modified c/Sic (c/Sic-Hfc) composite against high-speed atomic oxygen (AO) atoms was evaluated in a ground-based low Earth orbit simulating system. Energy Dispersive Spectrum, Scanning Electron Mic...
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capability of a Hfc-modified c/Sic (c/Sic-Hfc) composite against high-speed atomic oxygen (AO) atoms was evaluated in a ground-based low Earth orbit simulating system. Energy Dispersive Spectrum, Scanning Electron Microscopy, X-Ray Diffraction and Raman spectroscopy were employeed to investigate the damage behaviors of the material. The results show that Hfc was oxided by AO preferentially, while HfO2 and graphite films were its main products during AO exposure. The crystallization degree of the graphite film increased with the increasing of AO total flux. It's found that Sic areas had lower surface damage than Hfc areas, and SiO2 was its main reacting product. Ascribed to the evolution of surface craters, three-point bending strength of the specimens increased within the first 10 h exposure of AO and decreased thereafter. The damage mechanisms of AO over c/ Sic-Hfc were revealed also.
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