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To obtain thermodynamically stable single-phase high-entropy monoborides (HEMBs), the formation abilities of two-compound monoborides were evaluated in advance by first principles calculations, which were constructed from two cation combinations chosen from 11 transition metals including Ti, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, and Ni. And this method was extended to HEMBs on predicting the relative feasibility of synthesis and the tendency of phase segregation from the mean mixing enthalpy (μ local) and the standard deviation (σ local). Results showed that the contribution of entropy to free energy for entropy-stable HEMBs is large, and HEMBs with small σ local are easy to obtain the higher single-phase formation ability. In addition, four HEMBs ceramic with Vickers hardness (41–45 GPa) were synthesized as superhard materials. This work provides a realistic theoretical guidance for the design and performance research of HEMBs, and will effectively promote the application of superhard HEMBs ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]

Nowadays, it is challenging to dispose of the huge amount of sludge produced yearly. The chemical property of sludge significantly affects its reactivity and thermal transformation, which is also crucial for the treatment procedure. However, little research, if any, has been conducted on the correlations of chemical properties of various sludges, let alone a statistical study on sludge. Moreover, studies with one or several samples lack some generality. Based on the dataset of Chinese sludge during the last ten years, the correlations between chemical properties of municipal and industrial sludges were investigated by various methods. The chemical properties of sludges from distinct sources as well as their correlations clearly differ from one another. The majority of the sludge (∼83%) is distributed between 0.03 and 0.18 in terms of fuel ratio. Ash content in dry basis (A d) and carbon content in dry basis (C d) exhibit a clear negative correlation, while hydrogen content in dry basis (H d), nitrogen content in dry basis (N d), and C d display positive correlations. In addition, the majority of sludge ash contains a number of acidic oxides, which can alleviate ash issues such as slagging and fouling. Heavy metals that remain persistently during thermal treatment present potential ecological issues to the environment. Here, Cu in industrial sludge has the greatest fluctuation in heavy metal content, ranging from 65 to 6426 mg kg−1. Cd and Cu inside sludge ash have very high ecological risk, which should be the priority of ash treatment. This study offers important information for comprehending the correlation between chemical properties of sludge, while broadly and accurately predicting correlations is difficult, and some trends can be captured. [Display omitted] • The correlations of sludge chemical properties were quantitatively analyzed. • Noteworthy trends and variations were captured with images and expressions. • The distributions of acid, alkali, and alkaline earth metal oxides were studied. • The majority of sludge (∼83%) lies in the fuel ratio range of 0.03–0.18. • The concentration of Cu in industrial sludge exhibits the most variation. [ABSTRACT FROM AUTHOR]

As a typical ceramic tool, the wear resistance of Al 2 O 3 /SiC w composites is a prominent parameter in engineering applications. Therefore, how to improve its wear resistance has becomes a research emphasis of ceramic tools. In this work, the Al 2 O 3 /SiC w composites with improved wear resistance were prepared by a novel oscillatory pressure-assisted sinter forging (OPSF) process. The composites prepared by OPSF process not only exhibit higher density and significantly improved mechanical properties, but also own lower coefficient of friction than conventional sinter forging and hot oscillatory pressing processes. EBSD results indicated that the OPSF process could improve the texture of (0001) crystal face, low-angle grain boundaries, high-angle grain boundaries with special angles in the Al 2 O 3 matrix and enhance shear deformation at micro-scales, which are multiple contributed to enhanced wear resistance. Therefore, OPSF process is a promising technique to prepare ceramic-based cutting tools with excellent mechanical properties and wear resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • The co-firing of coal and municipal sludge with high moisture content was studied. • The more sludge co-fired, the less NO x emission. • There are higher flue gas temperature and NO x emission at lower moisture content. • Co-firing sludge from the medium-upper burner can reduce the layers of burner. • The shrunk-middle type is the optimum scheme of SA distribution. Using the current coal-fired power plant to treat sludge with large annual production is an efficient sludge treatment method. Nevertheless, the majority of the previous studies concentrated on sludge co-firing with low blending ratio and moisture content in utility boiler. Further analysis and discussion are necessary regarding the impact of sludge with high blending ratio and high moisture content on co-firing performance as well as the potential interactions between high moisture content sludge and coal during the co-firing process. The simulation results of the verified computational fluid dynamic (CFD) model can be regarded as numerical experiments. In the present research, CFD was used to analyze the co-firing characteristics of municipal sludge and coal in a 600 MW tangentially fired utility boiler. The impacts of sludge moisture content, blending ratio, blending strategy, and secondary air (SA) distribution on co-combustion characteristics and NO x emissions were investigated, and their potential synergistic effects were assessed. The co-firing of coal and sludge has little impact on the furnace outlet temperature while potentially lowering NO x emissions, provided that the net calorific value of the feeding of the mixture of sludge and coal is kept constant. The reduction of sludge moisture content can significantly improve co-combustion performance, but it also facilitates NO x production. Blending sludge from the position of the medium-upper burners can reduce the number of layers needed to burn the sludge in practical coal-fired boiler. Furthermore, the SA distribution has a major impact on the furnace outlet flue gas temperature and NO x content. The shrunk-middle type is the optimum scheme for SA distribution. This study contributes to a deeper knowledge of the actual co-firing of sludge and coal in the utility boiler and provides a possible theoretical foundation for the widespread, clean, and effective use of sludge. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) devices play an increasingly important role in solving the energy crisis. However, the conversion efficiency of the PV panel is small. Cooling of PV panels using phase change devices is an effective way to improve the working performance of PV panels. A phase change device with a two-level arrangement of metal-organic phase change materials (PCMs) is proposed. The PCM is filled in a metal cavity made of aluminium plates. A numerical model of the melting process of the combined PCMs is established, and the flow and heat transfer characteristics of the melting process are analysed. The results show that the temperature variation curve of the metal cavity wall close to the PV panel can be divided into three main stages according to the temperature increasing rate, i.e., the first rapidly rising stage, the slowly rising stage and the second rapidly rising stage. The temperature distribution inside the metallic cavity is more uniform compared to the temperature distribution inside the organic material cavity, and the flow in the metallic cavity is weaker, and the temperature controlling time shows a unimodal variation with the increase of gallium filling proportion in the studied ranges, and the optimal filling proportion is 56.9%. [Display omitted] • Solve the dimensionless temperature and velocity governing equations simultaneously. • Ambient and melting temperature influences different stage of temperature rising. • The flow in the metallic cavity is weaker than that in the organic cavity. • The temperature controlling ability of 2-stage heat sink is better than 1-stage. [ABSTRACT FROM AUTHOR]

The technology of oxy-fuel co-combustion is beneficial to consume the large amount of ultra-low volatile coal-based solid fuels (UCF). Moreover, the oxy-fuel co-combustion of various UCFs could also promote the development of coal-chemical industry and reduce the carbon emission in power plants. However, the co-gasification behaviors of various coal-based solid fuels blends at initial oxy-fuel co-firing stage are still vague, which need to be further studied. In the present, the co-gasification features of various coal-based solid fuels blends during initial oxy-fuel co-combustion process were investigated by oxy-fuel co-combustion system experimentally. The rise of O 2 concentration could obtain low Brunner−Emmet−Teller surface area and high Barrett-Joyner-Halenda average pore owing to the collapse of internal structures. The nitrogen gases (X–N) yields show a decreasing trend with the UCF proportion raised. The increasing temperature could promote the gas release of sample. The ash droplets observed on the surface of blend were formed by reactions between oxygen and carbon on the sample surface in 3% O 2 /97% CO 2 atmosphere, which are enlarged with temperature significantly. The present research could be beneficial for efficiency utilization of low-rank coal, together with the reduction of NO x emission and realization of carbon neutrality. • The co-gasification features at initial stage of oxy-fuel combustion were examined. • The synergistic effects of blends during co-gasification process were elucidated. • Tiny oxygen concentration results in collapsing of carbon and ash skeletons. • The addition of UCF could lead to the decreases of X–N yields in blends. • Ash droplets observed on the blend surface are enlarged with the T increased. [ABSTRACT FROM AUTHOR]