High-entropy ceramics has become a major focus in the research of new ceramics in recent years,with promising prospects of development and application in the aerospace industry.High-entropy oxide ceramic coatings,designed based on the high-entropy strategy,can better solve the deficiencies of key performance of thermal/environmental barrier coatings,including service life,oxidation resistance,and CMAS(Ca/Mg/Al/Si oxides) corrosion resistance at high temperatures.The article reviews the research progress of quintuple-element high-entropy rare earth salt materials in different systems as alternate candidates in the field of thermal/environmental barrier coatings in recent years,and summarizes the characteristics of the materials in terms of structure,performance and main application fields.Finally,the future development direction of high-entropy rare earth salt ceramic coatings is discussed to provide insights for further research and development as well as optimization of key performance of the new material systems.

The pure niobium was subjected to surface carburization by vacuum carburizing technology.The microstructure,elemental distribution and phase structure of the carburized layer were characterized by SEM,EDS and XRD.And the bonding strength,hardness and wear resistance of the carburized layer and substrate were evaluated by surface scratches,nano-indentations and friction and wear tests.The results show that the thickness of the carburized layer on pure niobium after carburizing at 1 400 ℃ for 12 h is about 37.8 μm,and the formed carburized layer consists of inner and outer layers.The outer layer is entirely composed of NbC phase while the inner layer contains NbC phase and Nb₂C phase.The carburized layer is dense and uniform without holes and cracks,presenting good bonding performance with the substrate.The hardness and elastic modulus of the pure niobium are greatly improved by carburizing,with the surface nano-hardness increasing from 1.8 GPa to 23.5 GPa.Compared with pure niobium,the friction coefficient of the carburized layer decreases from 1.03 to 0.62 during the friction process with Si₃N₄ friction pair,and the specific wear rate decreases from 21.6×10^-5 mm³/(N·m) to 1.12×10^-5 mm³/(N·m),indicating an improvement of wear resistance.Severe wear is observed on the surface of pure niobium with adhesive and abrasive wear mechanisms,while only slight wear appears on the carburized layer due to the presence of the NbC hard phase with the abrasive wear mechanism.

Cold compression tests of Ti-1300 alloy were carried out by Gleeble—3800 simulated testing machine.The effects of extrusion temperature,cold rolling reduction and heat treatment on the microstructure and mechanical properties of Ti-1300 alloy cold-rolled tubes were investigated through tensile tests at room temperature and microstructure observation.The results show that the Ti-1300 alloy cold-rolled tubes with 30% reduction extruded at the transformation temperature have a good strength-plasticity match.After solid solution treatment,cold-rolled tubes have lower strength and better plasticity,and the α+β two-phase solid solution microstructure mainly consists of a large number of spherical or elongated α phase and resi-dual metastable β phase.The β phase solid solution microstructure is mainly composed of equiaxed β grains.The strength of cold-rolled tubes in aging state is significantly improved,and their microstructure is mainly composed of spherical or elongated primary α phase,acicular secondary α phase and β matrix.

The effects of antimony(Sb) on grains and eutectic Si of hypoeutectic Al-Si alloy under gravity sand casting conditions were investigated by solidification temperature-time curves,polarized light microscope(PLM),scanning electron microscope(SEM),electron backscattered diffraction(EBSD),transmission electron microscope(TEM),and energy disperse spectroscope(EDS).The results show that the addition of Sb to the Al-7Si alloy results in a decrease in the nucleation temperature of primary α-Al grains and eutectic Si.The nucleation of primary α-Al grains becomes more difficult,and their average size increases from 319 μm to 353 μm.The mechanism of Sb modifying eutectic Si is that with Sb addition,the nucleation temperature of eutectic Si decreases,the solid solubility of Si in α-Al decreases,the chemical potential increases,the velocity of Si atoms discharging from α-Al increases,the growth rate of eutectic Si increases,and finally the eutectic Si becomes shorter and narrower.Sb does not play its role of modification by acting on the nucleation cores and twins of eutectic Si.

2023年7月20日,中国(株洲)先进硬质材料及工具国际交易中心启动招商。这是国内首个以先进硬质材料及制品贸易为主的国际交易中心,吸引了业内400余家企业和行业商协会参加启动式,株洲硬质合金集团有限公司、株洲欧科亿数控精密刀具股份有限公司、湖南富兰地切削工具有限公司。

近期爆火的云南菌子掀起了各地群众吃菌的热潮,成了新晋的“网红美食”。但伴随着鲜美味道而来的是超乎想象的危险——以“见手青”为代表的一类菌子具有毒性,若食用未经完全烹饪的菌子会造成食物中毒,轻者出现眩晕、腹泻、呕吐现象,重者产生幻觉,影响脑部神经。因此,在寻求美味时需注意食品质量安全,保证安全饮食。

Cemented carbide studs are the core wear-resistant parts in stud roller of high pressure roller mills.WC-11.5Co cemented carbide studs were subjected to high pressure gas quenching heat treatment with different technological parameters,and then their properties were compared and analyzed and field application was conducted.The experimental results show that the hardness,bending strength,fracture toughness and impact toughness of the cemented carbide studs are improved after gas quenching at 950~1 350 ℃ and 0.6 MPa,and reach their highest value when quenching temperature is 1 250 ℃.The results of the field application show that the cemented carbide studs treated with gas quenching at 1 250 ℃ and 0.6 MPa are not prone to breakage and edge collapse during their application,demonstrating excellent wear resistance,and their running time with materials is increased by 1.2~1.5 times and service life is obviously prolonged,compared with the studs without gas quenching heat treatment.

In the loaded organic phase extracted by N1923+isooctanol+sulphonated kerosene system,the low W/Mo ratio was the key factor limiting the separation efficiency of evaporative crystallization of W/Mo in the subsequent strip liquor.The process of eluting molybdenum from N1923 loaded organic phase by using workshop waste ammonia water as detergent to improve the W/Mo ratio was studied.The effects of pH value,reaction temperature,reaction time,and water to oil ratio on molybdenum elution rate were also investigated.The results show that under the conditions of pH=9.0,reaction temperature of 25℃,reaction time of 25 min,water to oil ratio of 4∶1,and standing time of 10 min,the unipolar elution rate of molybdenum reaches 88.18%.The secondary countercurrent washing of the eluted organic phase is found to have little effect on the elution rate of molybdenum with the increase of washing times.Using workshop waste ammonia water to wash the N1923 loaded organic phase to improve the W/Mo ratio is economically feasible,environmentally friendly,simple and effective,with high molybdenum elution rate and less tungsten loss.This study has certain reference significance for the separation of tungsten and molybdenum in the N1923 loaded organic phase.