转炉冶炼20CrMo钢的生产实践

介绍了石家庄钢铁有限公司转炉生产20CrMo钢的工艺技术及其产品质量状况和这一新工艺所带来的显著效益。     

An efficient parallel strategy for the perfect domination problem on distance-hereditary graphs

A graph is distance-hereditary if the distance stays the same between any of two vertices in every connected induced subgraph containing both. Two well-known classes of graphs, trees and cographs, both belong to distance-hereditary graphs. In this paper, we first show that the perfect domination problem can be solved in sequential linear-time on distance-hereditary graphs. By sketching some regular property of the problem, we also show that it can be easily parallelized on distance-hereditary graphs.     

Particle distribution and interfacial reactions of Al–7%Si–10%B<Subscript>4</Subscript>C die casting composite

Aluminum–boron carbide particle reinforced composite is an advanced material which can be used in applications such as neutron-shielding components, aircraft, and aerospace structures. In the microstructural characterization of an Al–7%Si–10%B₄C die casting, attention is particularly focused on particle distribution and interface reaction products between B₄C particles and the aluminum matrix. The quantitative analysis results show that, in a cross-section of the cast part, more particles concentrate in the center and fewer particles are present in the wall regions. Moreover, some particle segregation bands have been observed. The mechanisms of the particle migration are proposed to describe the phenomenon. However, the average particle fraction in any cross-section of the cast part is almost the same. A barrier layer consisting of several sublayers was detected on the surface of B₄C particles. Using electron diffraction in selected areas, it is found that these sublayers are composed of Al₃BC crystals, TiB₂ crystals, Si crystals, and coarse stick-shaped TiB₂ particles. In addition, it is observed that Si plays an important role in the formation of a dense barrier layer. The barrier layer can limit B₄C decomposition and improve B₄C stability in the aluminum melt.     

五年来我国有色金属工业结构调整状况及对策建议

本文总结了近5年来我国有色金属工业结构调整和产业升级的基本情况,即中国有色金属工业集约化程度、技装备水平提高,生产成本下降,行业整体实力增强。而这些成绩的取得都有赖于国家积极的财政政策及“债转股”政策的推动,有赖于深化企业改革及发挥市场资源配置的作用等等。同时,针对对当前及今后有色金属工业结构调整和产业结构升级所面临的问题,提出了有关对策建议     

Composite group vector space method for estimating melting and boiling point of pure organic compound

Composition Group Vector Space (CGVS) method for estimating melting and boiling point T _m , T _b of organic compound has been proposed, and the principle of this method has been elucidated. The models for estimating T _m , T _b have been established and the numerical values of relative parameters have been presented. The average percentage deviations of T _m , T _b estimation are 7.53 and 1.58, respectively, which show that the present method demonstrates significant improvement in applicability to predict the above properties, compared to conventional group methods.     

安钢高线粗中轧机导卫设计特点

介绍了安钢自行设计的高线粗中轧机导卫装置的设计原则和特点。     

导数火焰原子吸收法对调味品中锌的测定

将微量脉冲进样技术和导数火焰原子吸收法结合，建立了测定调味品中锌含量的新方法。该方法的检出限为0．013μg／mL，精密度4．46％，回收率96．67～113．33。     

A Simple Quasi-2D Numerical Model of a Thermogage Furnace

A simple quasi-2D model for the temperature distribution in a graphite tube furnace is presented. The model is used to estimate the temperature gradients in the furnace at temperatures above which contact sensors can be used, and to assist in the redesign of the furnace heater element to improve the temperature gradients. The Thermogage graphite tube furnace is commonly used in many NMIs as a blackbody source for radiation thermometer calibration and as a spectral irradiance standard. Although the design is robust, easy to operate and can change temperature rapidly, it is limited by its effective emissivity of typically 99.5–99.8%. At NMIA, the temperature gradient along the tube is assessed using thermocouples up to about 1,500°C, and the blackbody emissivity is calculated from this. However, at higher operating temperatures (up to 2,900°C), it is impractical to measure the gradient, and we propose to numerically model the temperature distributions used to calculate emissivity. In another paper at this conference, the model is used to design an optimized heater tube with improved temperature gradients. In the model presented here, the 2-D temperature distribution is simplified to separate the axial and radial temperature distributions within the heater tube and the surrounding insulation. Literature data for the temperature dependence of the electrical and thermal conductivities of the graphite tube were coupled to models for the thermal conductivity of the felt insulation, particularly including the effects of allowing for a gas mixture in the insulation. Experimental measurements of the temperature profile up to 1,500°C and radial heat fluxes up to 2,200°C were compared to the theoretical predictions of the model and good agreement was obtained.