Wear mechanism of a novel AlSiMgAl2O4Al2O3 composite used in the low vessel of an RH secondary refining furnace

A novel AlSiMgAl₂O₄Al₂O₃ composite brick was prepared and evaluated in the low vessel of an RH (the initials of Ruhrstahl and Hereaeus) secondary refining furnace; it was characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The results show that after use, the AlSiMgAl₂O₄Al₂O₃ composite has a functional gradient with an erosion zone–reinforced zone–original zone phase distribution, in which the phases in the erosion zone (0–1.8?cm) are a Mg-hercynite spinel solid solution, α-Al₂O₃, and minor amount of Al₃Fe₅O₁₂. Furthermore, the phases in the reinforced zone (1.8–5.0?cm) are γ-AlON, 21RSiAlON, SiC, Mg_0.388Al_2.408O₄, and α-Al₂O₃; i.e., the Al and Si in the composite are completely converted into non-oxide reinforced phases. Finally, the phases in the original zone (>5.0?cm) show no change. The reaction mechanism is as follows. During operation, a Mg-hercynite spinel solid solution is formed in the erosion zone due to a reaction between MgAl₂O₄ and FeO from a refinery operation. Therefore, the slag erosion of the material is improved. The Al and Si metals undergo active oxidation, and 21RSiAlON flakes are subsequently formed from the products of the metastable Al₂O(g), SiO(g), and N₂(g) in the ambient. The γ-AlON is formed by a carbothermal reduction nitridation of the α-Al₂O₃ and residual active carbon from the resin binder. The 21RSiAlON and γ-AlON reinforce the composite brick and improve its high temperature performance accordingly. Its service life is 110% that of the magnesia-chrome bricks used in the same period. The reaction model was also established.     

Electrical conductivity and gas sensitivity of Zn-Sb-O thick films

The thick film of Zn-Sb-O was prepared by coating the paste of nanoparticles mixture (Sb₂O₃:ZnO=1:3) on the alumina substrate, followed by sintering at 500-900 °C for 2 h in air. The electrical resistance and gas-sensing properties to benzene, alcohol and acetone of Zn-Sb-O films were found to be dependent on the change of phase structure caused by sintering temperature.     

引线框架材料QFe2.5加工工艺研究

本文介绍引线框架材料的发展现状，讨论引线框架用铜合金的强化机理，童点阐述引线框架用QFe2．5铜合金带材的性能及主要生产工艺（铸锭加热、热轧、时效退火等）。     

Ennoblement of stainless steel in natural seawater – A new explanation

The ennoblement of corrosion potential (E_corr) of passive metal immersed in seawater was investigated with electrochemical technology and epifluorescence microscopy. The in situ observation showed that the bacteria number increased on the metal surface according to an exponential law which was in the same way with the ennoblement of E_corr. At the same time, the anodic polarization current of high‐Mo stainless steel decreased in the initial days. According to the mix‐potential theory and the characteristics of polarization curves of high‐Mo steel in natural seawater, the ennoblement of corrosion potential may be induced by the decrease of the passive current density.     

HSLA-80/100钢的焊接

对ＨＳＬＡ－８０／１００钢的焊接性、焊接材料及焊接工艺进行了综述，并指出了现存在的主要问题。     

企业网络安全系统构建的探讨

企业信息化水平提高后，随着Internet的接入，企业网络的安全状况发生了很大变化。网络信息的安全问题也日益突出。本文由技术安全、安全管理等两方面具体措施的实施，说明了企业网络安全系统的构建方法。希望与各位同行共享和探讨。     

铝箔轧机开卷和卷取电机的谐波分析

本文结合一台2000mm铝箔轧机的电气传动系统，介绍铝箔轧机开卷、卷取电机的谐波计算方法，并分析铝箔轧机开卷、卷取的谐波特点。     

烧成温度对高铬砖显微结构的影响

利用扫描电子显微镜分析了 170 0℃、174 0℃、1780℃、182 0℃和 186 0℃烧成后高铬砖的显微结构。结果表明 :高铬砖的烧成温度不是越高越好 ,而是有一个合适的烧成温度 174 0℃。在该烧成温度下制得的高铬砖 ,其基质中的Cr2 O3晶粒尺寸适中 ,基质组织结构致密 ,基质和颗粒结合紧密 ,无裂纹 ,并且其力学性能最佳。     

薄板坯连铸浸入式水口结构数值模拟

使用有限元计算方法开展薄板坯连铸浸入式水口流场的研究 ,分别对水口不同浸入深度的流场分布、水口出口不同角度的流场分布进行计算。结果发现 :水口的浸入深度在 30 0mm时较为合理 ;水口的出口角度以R1 5、60°、45°为宜     

Study on Sintered Synthetic Hercynite Clinker

Special grade bauxite and roll scale were used as raw materials to investigate the influences of reducing atmosphere and firing temperature on sintering clinker. The results showed that: 1) The mixture of the materials could be sintered enough to synthesise hercynite under reducing atmosphere by adding reducing reagent ; 2) The hercynite dinker could be sintered to high density and the content of FeAl2O4 may attain 80～90% under the firing tempera-ture of 1550℃.