(Ti, Nb)(C,N) solid solution powder was used for preparing(Ti, Nb)(C,N)-based cermets at different nitrogen partial pressures.At the same time, Ti(C,N)-based cermets were considered as the control group.The effects of different nitrogen partial pressures during sintering on microstructure and mechanical properties of the cermets were studied by a scanning electron microscope with an energy spectrum analyzer and a Vickers hardness tester, combined with thermodynamic calculation.The results show that compared with Ti(C,N)-based cermets prepared with the same sintering process,(Ti, Nb)(C,N)-based cermets have finer grains, and only a few grains have special weak core-rim structure.There is a binder phase Ni-rich gradient layer on the surface of vacuum-sintered(Ti, Nb)(C,N)-based cermets.As the nitrogen partial pressure during sintering increases, the hard phase in the surface layer of(Ti, Nb)(C,N)-based cermets abnormally grows up.The formation of the gradient structure of(Ti, Nb)(C,N)-based cermets is due to the difference in N activity between the surface and the core of the material sintered at different nitrogen partial pressures, and different diffusion direction and rate of Ti, Nb and other atoms, attributed to thermodynamic coupling.

Embedding metal cations in the layered structure of vanadium oxides can significantly improve the electrochemical performance of the vanadate materials.According to the types of pre-embedded metal cations, the synthesized vanadates are mainly divided into alkali metal vanadates, transition metal vanadates and alkaline-earth metal vanadates.The latest research progress of these vanadate electrode materials is reviewed in this article, including preparation process, reaction mechanism, electrochemical performance, performance optimization methods and so on.Finally, the future research direction of vanadate electrode materials is prospected.

The Li-doped compound Na_0.75Li_0.25Mn_0.75O₂ and the Mg-doped compound Na;Mg;Mn;O;were synthesized by solid reaction process.Phase composition and morphology of the obtained materials were characterized by using X-ray diffractometer(XRD) and scanning electron microscope(SEM).Sodium storage performance of the materials was tested by galvanostatic charge-discharge and cycle voltammetry.The experimental results show that both Li-doped and Mg-doped materials present layered morphology and P2 crystal structure.The initial discharge capacity of Na_0.75Li_0.25Mn_0.75O₂is 146 mA·h/g, and its capacity retention rate after 50 cycles is 79.4%.The initial discharge capacity of Na_0.75Li_0.25Mn_0.75O₂ reaches 158 mA·h/g, and its capacity retention rate after 50 cycles is 64.1%.Doping with Li element can more significantly improve the cycle performance of the materials than doping with Mg element.

The effect of Mn content on microstructure and mechanical properties of FeMnCoCr series as-cast dual-phase high-entropy alloys was investigated by testing means of XRD,BSE and EBSD,and tensile experiments.The results show that with the decrease of Mn content,FCC phase and HCP phase in the high-entropy alloys transform to BCC phase,and there is only a single BCC phase in Fe₇₀Mn₁₀Co₁₀Cr₁₀ alloy.The crystal structure of Fe₅₃Mn₂₇Co₁₀Cr₁₀,Fe₅₅Mn₂₅Co₁₀Cr₁₀and Fe₅₈Mn₂₂Co₁₀Cr₁₀ alloys has little change after deformation.Part of FCC phase in Fe₆₀Mn₂₀Co₁₀Cr₁₀alloy transforms into HCP phase after deformation,and the phase variation is about 10%.FCC phase and HCP phase simultaneously transform into BCC phase during deformation of Fe₆₅Mn₁₅Co₁₀Cr₁₀,which causes TRIP effect and alloy elongation of 42%.When the Mn content(molar fraction)changes from 20%to 27%,the yield strength of the high-entropy alloys gra-dually decreases,and both the tensile strength and elongation decrease at first and then increase.With the further decrease of Mn content from 20%,the tensile strength of the high-entropy alloys still shows an increasing trend.

In order to clarify carbon content range of cemented carbides with the best microstructure and mechanical properties,WC-10 Co composite powders with different carbon contents were prepared,and the cemented carbides were obtained by pressing and sintering.The effects of carbon content on microstructure and mechanical properties of the cemented carbides were analyzed by metallographic microscope,scanning electron microscope,hardness tester and electronic universal mechanical testing machine.The result show that there is decarburized phase in the cemented carbides with less carbon content than 5.34%,and carburized phase appears in the cemented carbides with greater carbon content than 5.50%.When the carbon content is 5.36%~5.47%,the cemented carbides are in the WC+Co two-phase region.When the carbon content is lower than 5.38%,WC grains present a nearly elliptical shape.When the carbon content is increased to 5.41%,the edges of WC grains tend to be flat and straight,and as the carbon content continues to increase,the growth of WC grains is more obvious,until they develop into the balanced morphology of triangular prism shape.When the carbon content ranges from 5.41%to 5.47%,the cemented carbides have better hardness and flexural strength than those with other carbon contents,and their hardness and flexural strength are 1655~1668 kg/mm² and 3921~4475 MPa,respectively.

The effect of ruthenium addition on the microstructure of WC-Co cemented carbides was discussed.The results show that ruthenium addition has a significant effect on the growth and average size of WC grains in WC-Co cemented carbides.With the increase of ruthenium content, the phenomenon of abnormal growth of WC grains in the cemented carbides gradually decreases until it disappears, the average grain size of WC decreases to a certain extent, but WC grain growth orientation does not show a clear tendency.After ruthenium element is added to WC-Co cemented carbides, it is mainly dissolved in the Co phase, and ruthenium grains significantly grow up by sintering.

WC based cemented carbide with Co-Mo-Ni new bonding phase was prepared by spark plasma sintering.The friction and wear characteristics of the new bonding phase cemented carbide and TC4/GCr15 friction pairs were studied by using the ball-face friction mode on UMT—2 friction and wear testing machine.The results show that under the same friction condition,the friction coefficient of the cemented carbide is large in the most cases when TC4 is used as a dual part,and the wear form is mainly adhesive wear with lower load,while abrasive wear occurs on the basis of adhesive wear with higher load.When GCr15 is used as a dual part,the wear form is mainly plastic deformation with lower load,and local abrasive wear occurs with higher load.After abrasive wear,the plastic deformation on surface of the cemented carbide is significantly reduced,and the wear rate also decreases.

AlCrN coatings were deposited on cemented carbide by gas ion source-assisted arc ion plating and conventional arc ion plating,respectively.The microstructure,composition,hardness,bonding strength and wear resistance of AlCrN coatings prepared by these two methods were compared and analyzed.The results show that the surface of AlCrN coatings prepared by the two methods is smooth,and the bonding strength of all the coatings is above 100 N.The thickness of AlCrN coatings prepared by conventional arc ion plating is relatively thin,the proportion of metal atoms is small,the surface roughness is low,the friction coefficient is small,and the hardness and wear resistance are also low.Since the gas ion source-assisted deposition can improve the ionization rate of metal atoms,the growth rate of AlCrN coatings prepared by gas ion source-assisted arc ion plating is faster,and the hardness and wear resistance are improved.

随着经济的不断发展以及人们生活水平的提高,食品安全逐渐成为备受关注的焦点。然而,随着食品的种类越来越丰富,新的食品安全问题不断涌现,严重危害人们的身体健康。在日常生活中,一日三餐都离不开食物,食品安全于我们而言是重中之重,我们要注意防范伪劣食品,并做好果蔬的清洗工作。一、伪劣食品防范"七字法"一防"艳"。对颜色过分艳丽的食品要提防,如目前上市的草莓像蜡果一样又大又红又亮、咸菜梗亮黄诱人、瓶装的蕨菜鲜绿不褪色等,需留心是否添加了色素。二防"白"。凡是食品呈不正常、不自然的白色,十有八九会存在漂白剂、增白剂、面粉处理剂等化学品的危害。

Tungsten slag contains not only valuable elements such as W,Sn,Ta and Nb,but also toxic elements such as As and Pb.If tungsten slag is randomly stacked or buried,not only the environment will be polluted,but also its value as secondary resources will be wasted.This paper reviews the research progress of comprehensive recovery and utilization technologies of alkali-boiled tungsten slag,such as hydrometallurgy,beneficiation-metallurgy combination,pyro-hydrometallurgy combination and pyrometallurgy.Their technical advantages and disadvantages are analyzed.It is pointed out that pyrometallurgy has the characteristics of short process flow and will become the development direction of comprehensive utilization technology of alkali-boiled tungsten slag.