Latest ArticlesFor the improvement of the fluidity of castables with recycled aggregates of mullite-SiC bricks due to their high porosity, high water absorption and massive cracks, silica sol was used to impregnate mullite-SiC brick aggregates. The effect of silica sol concentration on the aggregate properties of mullite-SiC bricks was investigated. The microstructures and the element distributions of modified mullite-SiC bricks aggregate were analyzed by scanning electron microscopy coupled with energy dispersive spectroscopy. The water wettability of mullite-SiC brick aggregates was characterized via water contact angle measurement. The results show that after the impregnation of mullite-SiC brick aggregates, the water absorption of mullite-SiC brick aggregate reduces from 6.9% to 2.6%, and the water contact angle decreases from 55° to 7°, thus improving the water wettability of the aggregate. The impregnated mullite-SiC bricks were used as recycled aggregates instead of brown corundum in Al2O3-SiC-C castables. In addition, the effect of aggregates on the properties of castables was also investigated. The results indicate that Al2O3-SiC-C refractory castables with silica sol concentration of 15% modified mullite-SiC bricks aggregates after heat-treated at 1 450 ℃ have the minimum apparent porosity of 17.1% and the maximum cold compressive strength of 73.7 MPa, which is 45.7% greater than the strength of castables with brown corundum as aggregates. Meanwhile, the residual strength and the residual strength ratio of castables after thermal shock are increased by 69.4% and 24.1%, respectively.
The residual mechanical properties and microstructure of UHPC mixed with 6, 8, 12 mm copolymer formaldehyde fiber and steel fiber after high temperature were studied. The test results show that at 400 ℃, only plain concrete bursts. At 500 ℃, the steel fiber UHPC specimen burst, while the UHPC specimen with single copolymer formaldehyde fiber and mixed with two kinds of fiber can still maintain relatively integrity, and the latter has higher residual strength at high temperature. SEM and pore structure show that the copolymer formaldehyde fiber in UHPC can be closely bonded to the matrix after steam curing at high temperature. The pore formed by fiber melting at 165 ℃ can effectively relieve and release steam pressure, keep the concrete matrix intact and prevent it from cracking at 500 ℃. The research results reveal the mechanism of the copolymer formaldehyde fiber on the high temperature performance of concrete, which has great reference value for its application in UHPC.
In addition to incandescent lamps, white light-emitting diode and nonlinear supercontinuum white light, recent studies focus on the production of continuum broadband white light by irradiating different active materials with near-infrared constant-wave lasers. In this review, we introduced and categorized different materials that exhibit NIR laser driven white light emission, i.e., inorganic phosphors, hybrid nanostructures, carbon-based materials, organometallic compounds and rare-earth complexes. The intrinsic photophysical behavior of this process in terms of spectral characteristics, temperature evolution and photoelectric response was discussed. In addition, the different mechanisms of while light generation and highlight potential applications of this process were also represented. Finally, the past results and point future research direction for this optical process were summaried.
Data-driven Machine Learning (ML) has been widely used in materials performance optimization and novel materials design due to its ability to quickly fit potential data patterns and achieve accurate prediction. However, the results of data-driven ML are often inconsistent with the materials basic theory or principle, which results mainly from the lack of the guidance of materials domain knowledge, e.g., the correlation among descriptors and the driving mechanism associated with the properties. Herein, by analyzing the characteristics of materials data and the modeling principle of data-driven ML methods, we clarify the three main contradictions occurring to the application of ML in materials science, i.e., the contradictions between high dimension and small sample, complexity and accuracy of models, learning results and domain knowledge. Following this, we propose the ML method embedded with materials domain knowledge to reconcile these three contradictions. Further, surrounding the whole ML process including target definition, data collection and preprocessing, feature engineering, model construction and application, we explore some key techniques to realize domain knowledge embedding by summarizing the related basic and exploratory efforts. Finally, opportunities and challenges facing the ML method embedded with domain knowledge are also discussed.
Applications, evaluations, funding, and management of National Natural Science Foundation of China programs on inorganic nonmetallic materials in 2021 were summarized and statistically analyzed. The specific measures of inorganic nonmetallic materials on scientific fund reform, talents and academic teams, academic exchange and seminars, in-depth researches on the 14th five-year and medium and long-term development plan were introduced detailedly.
Microwave absorbing materials are widely used in military and civil fields. The current research focusses on novel microwave absorbing materials with intense absorption, wide bandwidth, light weight and thin thickness. Black phosphorus (BP) and sulfur-doped black phosphorus (BP-S) crystals were prepared at a high temperature and a high pressure, and then BP and BP-S nanosheets were obtained via liquid-phase exfoliation. Compared with BP, the complex permittivity and εr″/εr′ of BP-S are enhanced at 1.0-16.5 GHz. The minimum reflection loss (RL) reaches -41.4 dB at 9.6 GHz, and the RL exceeding -10 dB in a frequency range of 7.0 to 16.1 GHz is obtained for the absorber thickness of 1.0-2.0 mm. The minimum RL frequency dependence of the absorber thickness for BP-S comply with a λ/4 matching model. BP-S has broad application prospects as a high-performance microwave absorbing material.
The mechanism of conventional photocatalysis is based on photodegradation effect of photo-induced carrier when the surface of photocatalyst nanoparticles is irradiated by light. For this photocatalysis technique with outside-light-supply mode, a light utilization efficiency is rather low, the catalyst is often out-of-work, and recycle cast is high, which restrict its practical application in environmental protection. To solve the problems above, a photocatalytic system was prepared via the construction of a non-crystal fiber-Sn3O4 nanosheet. The results show that Sn3O4/optical fiber in the photocslayst can enhance the photocatalytic performance. In addition, the wave guide of incoherent light targeted to photocatalysis and the inner-light-supply photocatalysis were also proposed for the development of optical wave guide theory, and this photocatalyst with Sn3O4/optical fiber could have a promising potential in water treatment application.
The salt control and desalination for treating the secondary damage of silicate materials caused by sticking ointment and soaking method commonly used in salt damage control were investigated by a spraying atomized water vapor method. The salt distributions in the samples before and after treatment were analyzed by laser particle size analysis, X-ray diffraction, visible shortwave infrared hyperspectral imaging analysis and ion chromatograph. The results show that after the atomized water vapor enters the sample, the area where the sample is wetted is a hemisphere centered on the spray point, and the salt in the superficial layer of the sample is transported to the outside of the hemispherical wetting area. Also, the route of controlling the salt distribution by atomized water vapor was proposed, and the feasibility of preventive treatment of salt damage in silicate material was preliminarily verified.
With the developments of the electronics and energy technologies, studies on nanostructure engineering of the emerging thermoelectric materials and thermal logic devices are drawing increasing attentions. In this review, we focus on several promising thermoelectric materials, and study the mechanisms of thermal transport engineering in the atomic and nano-scale structures theoretically and experimentally, with a micro-nano scale thermal transport measurement system developed by our research group. Such research focuses include: the atomic alloying of Si1-xGex alloy films with full components, the mismatched interfaces of Bi2Ca2Co2Oy layered-structure single crystals, the ionic localized resonances of superionic conductor A0.5RhO2 (A=K, Rb, Cs) single crystals, and the loose microstructures in quasi-one-dimensional ZrTe5/HfTe5 single crystals as well as the SnSe2 intercalations in SnSe single crystals. The influences of various scale structures and interatomic forces on the thermal transport properties are summarized, offering effective engineering strategies on developing potential thermoelectric materials with low thermal conductivity and excellent thermoelectric performance. Besides, the realization of effective dynamic engineering of thermal conductivity using phase transition, along with its potential applications in thermal logic devices are introduced.
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