硫化锌精矿两段逆流氧压浸出原理及综合回收镓锗工艺研究

文章分析了硫化锌精矿氧压浸出各元素的行为,阐明了硫化锌精矿两段逆流氧压浸出的原理及综合回收镓、锗的工艺。说明了两段逆流氧压浸出综合回收镓、锗的生产工艺特点。     

硫化锌精矿高温高压浸出技术

介绍了硫化锌精矿高温高压浸出技术的发展和硫化锌精矿高温高压浸出的工艺和动力学研究。     

NdFeB基纳米双相复合永磁材料研究进展

介绍了近年来NdFeB基纳米双相复合永磁材料的研究进展,主要从纳米复合双相材料的耦合机制和矫顽力机制等理论方面进行了总结,包括晶粒交换耦合作用、成核理论、钉扎理论、成分关系理论、自钉扎理论、晶体内部缺陷钉扎作用、脱溶相对主相晶粒钉扎作用等相关理论,然后从元素替代、掺杂元素对双相复合材料磁性能的影响进行了阐述。     

不锈钢耐蚀性能的价电子理论研究进展

 在介绍固体与分子经验电子理论（EET理论）和扩展的EET理论的基本原理和方法的基础上,综述了这一理论在钢铁材料成分设计、组织结构转变和性能预测方面的应用及其研究现状;归纳了在晶体价电子结构理论角度上探讨不锈钢中合金元素的作用及不锈钢抗腐蚀机理的研究进展;并提出了采用扩展的EET理论,从合金元素对晶体价电子结构影响的层次上揭示不锈钢抗腐蚀性能的本质以及发展新型不锈钢的计算合金设计新方法。     

纳米硫化锌颗粒制备工艺与研究进展

硫化锌为典型直接带隙半导体材料,具有优异的光学、电学、着色以及红外性能,因此在国防军工、化学化工以及电子材料制备及应用领域扮演着重要的角色。伴随当今器件微型化、智能化、集成化发展趋势的推进,纳米颗粒制备合成技术日渐引起了人们的广泛关注。基于此,本文针对纳米硫化锌颗粒的常用制备工艺进行了总结,并简要对于研究进展进行了阐述,以期为推动纳米硫化锌颗粒研发贡献力量。     

氧压浸出硫回收粗硫池设计计算

硫化锌精矿加压浸出全湿法炼锌工艺是硫化锌精矿不需焙烧脱硫直接浸出工艺。在浸出过程中,大部分硫转化为元素硫进入浸出渣中,浸出渣经处理分离出硫磺,避免了SO_2气体及尾气有可能泄漏对大气的污染。从加压浸出渣中回收元素硫是一个物理过程,其原理是利用元素硫在约120℃时熔化成液态的特点,达到与浸出渣中其它杂质分离。本文对硫回收工艺中粗硫池设计计算进行阐述。     

甘蔗渣提取木质素作为硫化锌精矿氧压浸出分散剂的应用研究

针对采用硫化锌精矿氧压浸出工艺的炼锌企业采购木质素比较困难,木质素含氯元素较高且其含的有机物在使用过程中难于分解的问题,通过实验研究对比甘蔗渣提取木质素和市场采购木质素在硫化锌精矿氧压浸出的分散效果,从浸出液成份、锌浸出率、浸出渣性状进行综合分析对比。结果表明：甘蔗渣提取木质素具备作为硫化锌精矿氧压浸出分散剂使用的各项特性,浸出液含有机物、氯离子明显下降。     

硫化锌精矿加压氧浸的矿浆降温降压冷却方法

介绍了一种硫化锌精矿加压氧浸的矿浆降温降压冷却方法及装置,取消了调节槽,简化了设备配置,缩短了生产工序,解决了生产中矿浆容易堵塞系统的问题,熔融硫可以采用热滤法生产元素硫,打破了"闪蒸一调节"的传统观念,可以采用一步闪蒸,优化了锌加压氧浸矿浆降温降压的方法及装置。     

硫化锌精矿焙烧浸出与直接浸出结合提锌同时除铁的方法

介绍了一种硫化锌精矿焙烧浸出与直接浸出结合提锌同时除铁的方法,利用硫化锌精矿氧压浸出除铁原理,浸锌同时除铁,取消了热酸浸出的除铁过程,简化了设备及工艺流程,提高了锌回收率,可以达到节能、环保、高效。     

纳米硫化锌的制备与应用状况

介绍了纳米硫化锌的制备方法及制备原理,详细阐述了目前纳米硫化锌在各领域中的应用状况,指出开发能制备尺度均匀、形状及光电性能优异、并且易于实现工业化的纳米硫化锌粉体的方法及掺杂方法是目前急需解决的问题。     

Recrystallization of silicon nitride during hot pressing

Conclusions The recrystallization processes taking place in a silicon nitride-base material produced by the hotpressing technique were studied by the methods of metallography and electron microscopy. It is shown that the starting grains of such a material become comminuted as a result of hot pressing. This is accompanied by partial recrystallization, which has a localized character. The number of large grains is negligible, and these grains have no significant effect upon the process of structure formation in the material.Translated from Poroshkovaya Metallurgiya, No. 12 (156), pp. 74–77, December, 1975.     

Abnormal Grain Growth and Recrystallization in Al-Mg Alloy AA5182 Following Hot Deformation

Abnormally large grains have been observed in Al-Mg alloy AA5182 sheet material after forming at elevated temperature, and the reduced yield strength that results is a practical problem for commercial hot-forming operations. The process by which abnormal grains are produced is investigated through controlled hot tensile testing to reproduce the microstructures of interest. Abnormal grains are shown to develop strictly during static annealing or cooling following hot deformation; the formation of abnormal grains is suppressed during plastic straining. Abnormal grains grow by static abnormal grain growth (SAGG), which becomes a discontinuous recrystallization process when abnormal grains meet to form a fully recrystallized microstructure. Nuclei, which grow under SAGG, are produced during hot deformation by the geometric dynamic recrystallization (GDRX) process. The mechanism through which a normally continuous recrystallization process, GDRX, may be interrupted by a discontinuous process, SAGG, is discussed.     

Improved microstructure and properties of 6061 aluminum alloy weldments using a double-sided arc welding process

Due to its popularity and high crack sensitivity, 6061 aluminum alloy was selected as a test material for the newly developed double-sided arc welding (DSAW) process. The microstructure, crack sensitivity, and porosity of DSAW weldments, were studied systematically. The percentage of fine equiaxed grains in the fully penetrated welds is greatly increased. Residual stresses are reduced. Porosity in the welds is reduced and individual pores are smaller. It was also found that the shape and size of porosity is related to solidification substructure. In particular, a weld metal zone with equiaxed grains tends to form small and dispersed porosity, whereas elongated porosity tends to occur in columnar grains.     

聚变堆中面向等离子体的钼板材制备工艺研究

通过对比采用轧制方法和锻造方法生产的钼板材的组织和力学性能,研究了面向等离子体钼板材的制备工艺。结果表明:采用板坯轧制方法生产的钼板材经过完全再结晶退火之后,尽管密度较大,但轧制面方向上金相组织晶粒较粗大,强度值明显偏低;采用钼棒坯经过大加工率锻造加工后生产出的钼板材同样经过完全再结晶退火处理后三向晶粒组织和强度值均匀,可满足聚变堆中钼板材料的使用要求,且进一步加大锻造加工率,可进一步提高板材的强度和密度。     

Warm Deformation of Low Carbon Steel Using Forward Extrusion-Equal Channel Angular Pressing Technique

A combination of extrusion and equal channel angular pressing (ECAP) was used to deform a plain low carbon steel. This process consists of two successive deformations by extrusion and ECAP in a single die (Ex-ECAP). Cylindrical samples were heated to predefined temperatures (650 and 850 ℃) and then pressed through a die channel with crosshead speed of 10 mm/s. Microstructure and resultant mechanical properties of processed material were studied. The results showed that pressing temperature has a significant effect on the resultant microstructure. While at 650 ℃, the cold worked structure with elongated ferrite grains were obtained, and at 850 ℃ the microstructure consisted of elongated ferrite grains and very fine grains at their boundaries as a consequence of continuous dynamic recrystallization (CDRX) of ferrite phase. Also at 850 ℃, a particular microstructure consisted of cold worked ferrite and static recrystallized grains on shear bands was obtained.     

Texture development during recrystallization of aluminium containing large particles

The recrystallization process in heavily deformed commercially pure aluminium containing large intermetallic particles was studied by in situ neutron diffraction texture measurements and various microscopical techniques including texture measurements in local areas and simultaneous determination of size and orientation of individual grains. The formation and growth of recrystallization nuclei at the particles and in the matrix were examined by correlating the measured change in texture to the observed change in microstructure. It was found that prolific nucleation of grains having a wide spread of orientations takes place close to larger particles or clusters of particles early in the recrystallization process. The texture of fully recrystallized material, however, contains only a relatively weak random component showing that the randomisation effect of the particles was limited. This was ascribed to a slower growth of randomly oriented grains compared with those with other orientations.     

R-curve behaviour of Al2O3 ceramics

The fracture micromechanics and underlying physical processes of fracture in Al₂O₃-based ceramic specimens have been studied as a function of grain size by instrumented in situ dynamic scanning electron microscopy (SEM) using the double torsion technique. The toughness is found to increase with grain size. Crack bridging is found to extend over hundreds of grain diameters behind the crack tip, resulting in R-curve behaviour. Evidence is amassed which points to frictional energy dissipation, rather than distrubuted microcracking or crack-closure due to elastic ligaments, as the dominant contribution to toughening. The friction occurs at grains which bridge the crack faces and are pulled out as the faces separate. Restraining stresses, which constrain the bridging grains in their sockets, are believed to be the result of both grain morphology and the thermal expansion anisotropy of the material. Simple modelling indicates that only a few percent of the grains need be involved in the frictional process to account for the toughening. The conclusion is supported by hysteresis measurements.     

Grain size effects on the texture evolution of α-Zr

The texture evolution during the plastic deformation at room temperature of Zr-2.5Nb round bars was studied in specimens with two different α-Zr grain sizes. It was found that during axisymmetric compression the strain producing mechanisms active during deformation depended on the grain size. In fine grained specimens there are two main phenomena characterizing the evolution of texture: (i) a rapid rotation of the grains about their 〈c〉 axis to form a <112¯0> fiber at strains below −0.20 and, (ii) a slow and progressive reorientation of the 〈c〉 axes of the grains towards the compression axis to form a [0001] fiber texture tilted approx. 20°. The latter process takes strains larger than −0.80. In coarse grained material, the texture evolution is characterized by a sudden rotation of the 〈c〉 axes to become aligned parallel to the compression axis at strains as low as −0.05. It is shown using a self-consistent viscoplastic model of texture evolution that the type of texture obtained depends on the mechanism controlling 〈c〉 axis deformation. In fine grained material prismatic slip, with basal and pyramidal 〈c + a〉 slip acting as complementary deformation modes, control the texture evolution process. In coarse grained material twinning is responsible for the final texture observed.     

Characterization of the kinetic and mechanistic differences between free-surface and bulk grain growth in WC-Co materials

The rate of grain growth at different high temperatures in the bulk and at the free surface of a WC-Co substrate was measured. The microstructure, phase evolution, and elemental composition at the free surface were characterized at various stages of the grain-growth process and compared to equivalent characteristics of the bulk. A dramatic difference in the rate of grain growth between the free surface and the bulk of the material was observed. Grains in the free surface grew at a much faster rate than those in the bulk. Since this fast rate of growth was found to coincide with the vaporization of the binder phase from the free surface, it is suggested that this increase in the rate of growth is related to a change in the growth mechanism from an interfacial reaction limited growth in the bulk to a surface diffusion rate limited growth at the free surface. The contact points between grains provide bridges for atomic transport from high free-energy regions (small grains) to low free-energy regions (large grains); hence, the contiguity of the material has a strong influence on the rate of growth.