Strong tribocatalytic dye degradation by tungsten bronze Ba4Nd2Fe2Nb8O30

The triboelectric effect has recently demonstrated its great potential in environmental remediation and even new energy applications for triggering a number of catalytic reactions by utilizing trivial mechanical energy. In this study, Ba₄Nd₂Fe₂Nb₈O₃₀ (BNFN) submicron powders were used to degrade organic dyes via the tribocatalytic effect. Under the frictional excitation of three PTFE stirring rods in a 5 mg/L RhB dye solution, BNFN demonstrates a high tribocatalytic degradation efficiency of 97% in 2 h. Hydroxyl radicals (?OH) and superoxide radicals (?O₂－) were also detected during the catalysis process, which proves that triboelectric energy stimulates BNFN to generate electron-hole pairs. The tribocatalysis of tungsten bronze BNFN submicron powders provides a novel and efficient method for the degradation of wastewater dye by utilizing trivial mechanical energy.     

Corrosion behavior of Cu–Sn bronze alloys in simulated archeological soil media

The corrosion behavior of synthetic Cu–Sn bronze alloys with six different Sn contents was examined through an electrochemical test and a synthetic test in a simulated corrosive medium. The mechanism of corrosion and the morphology of the corroded surfaces were characterized through field emission scanning electron microscopy equipped with energy-dispersive spectroscopy. At the corrosion potential, the corrosion behavior appears to be determined by the charge transfer step and the diffusion process. It was found that the bronze-IV (Cu–26.8Sn) specimen exhibited the best corrosion resistance, as evidenced by a low corrosion current density and a high impedance. This improvement resulted from an increase in the content of the Cu–Sn solid solution in the alloy, which was conducive to forming a relatively more protective passive film on the surface of the bronze alloy. This finding would be valuable in the anticorrosion protection of archeological artefacts after their excavation.     

全球趋向统一的《粉末冶金零件材料规范》

评述了ISO 5 75 5“烧结金属材料—规范”和美国MPIF标准 35的变迁和趋向统一。阐述了“最小强度值”的意义。说明了我国粉末冶金结构零件材料标准的现状     

Reaction between the tetragonal tungsten bronze niobate K2Sr4Nb10O30 and the perovskite Pb(Mg1/3Nb2/3)O3

The search for dielectric materials with a high dielectric constant and ′_r = ƒ(T) curves with a flat profile fitting the X7R specification is still ongoing. Promising results were obtained by mixing compounds with closely related structures, such as the tetragonal tungsten bronze (TTB) niobate K₂Sr₄Nb₁₀O₃₀ and the perovskite Pb(Mg_1/3Nb_2/3)O₃ (PMN). The present study, based on three methods of synthesis, explores the origin of the spreading out of the dielectric curves ′_r = ƒ(T). For the composition 10x K_0.2Sr_0.4NbO₃ (KSN) + (1 − x)Pb(Mg_1/3Nb_2/3)O₃ (PMN) with x = 0.3–0.6, the three synthesis methods provided similar characteristics and for the highest perovskite ratio (x = 0.3), the ′_r = ƒ(T) curve exhibits a flat profile. When lithium is used as a sintering agent, ′_r = ƒ(T) curves present a linear dependency with the temperature. These materials are also characterized by a structural and a microstructural inhomogeneity. Two phases TTB and perovskite type, different from KSN and PMN, are present after calcination and sintering, but not evenly distributed. The PbO loss during sintering also contributes to the evolution of the properties of the material.     

采用一次模压成形工艺生产高性能烧结NdFeB磁环

介绍了采用一次模压成形工艺批量生产高性能烧结钕铁硼磁环的新工艺 ,指出了目前该工艺仍存在的一些问题 ,同时概述了该工艺的应用前景     

Industrialization of High Performance Sintered NdFeB Magnets

Sintered Nd-Fe-B magnet was manufactured by advanced equipment via a SC (Strip casting) technology.It has integrative performance.     

高强度烧结钢

为开拓粉末冶金材料新的应用领域，近年来对高强度烧结钢进行了大量的研究与开发。本文简要介绍Ｈｏｇａｎａｓ公司开发的一些高强粉末冶金材料及对一些高强度烧结材料尺寸变化的控制。     

影响凹印铜金粉印金光泽度的主要因素

在研究国内外铜金粉的微观形貌、厚度、水面遮盖率、定向排列、光泽度和粒度分布的基础上，分析了影响凹印铜金粉印金光泽度的主要因素。结果表明，国产铜金粉颗粒级差大、细小颗粒所占比例过多、金属片太厚、水面遮盖率小、定向排列不好等是影响国产铜金粉印金光泽度的主要因素。     

应用10mm薄板铸锭制备的NdFeB烧结磁体

NdFeB薄板铸锭具有晶粒细，富钕相分布均匀及在稀土含量较低时可以防止α－Fe相出现的特点，是一种适合制备高性能烧磁体的合金铸锭，本文介绍了一种用10mm薄板铸锭和球磨制粉方法制备烧结磁体的工艺，在设备要求较低的情况下制备得到了Br=1.37T,(BH)max=320kJ/m^3(40MGOe)的烧结磁体，同时比较了使用常规铸锭和常规工艺的结果，强调了氢爆法在该工艺中的重要作用，最后对该工艺的改进方向和10mm铸锭的应用前景进行了阐述。     

Recent developments of high-performance NEOMAX magnets

For further improvement in achieving extremely high magnetic properties of Nd- Fe- B sintered magnets, extensive investigation has been done to densify the magnet up to the theoretical value, to increase the volume fraction of the Nd ₂Fe₁₄B matrix phase, and to achieve a high degree of alignment. By controlling chemical composition and the amount of constituent phases,improving particle size distribution, and adopting the isostatic pressing method to get better alignment of fine particles, we have succeeded in obtaining a high-performance magnet having residual flux density (B_r) of 1.495 T (14.95 kG), maximum energy product [(BH)_max] of 431 kj/m³ (54.2 MGOe), and intrinsic coercivity (iH_c) of 845 kA/m (10.62 kOe).