Preparation and properties of nanosize MnZn ferrite from δ-FeOOH

Ferrous ion was transformed into feroxyhyte (δ-FeOOH) by oxidation. Then, manganese sulfate and zinc sulfate in some ratio were added to the feroxyhyte solution. The co-precipitation was boiling reflux conditions sometime under constant stirring. The nanosize MnZn ferrite powder was formed. The mechanism of preparation of the nanosize MnZn ferrite was discussed, and the formation of feroxyhyte which was playing a key role during the process was mentioned. The properties of powder was tested by means of X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results show that the samples of spherical particles about 20 nm, which have characteristics of ferrimagnetism, has larger saturation magnetization, but the remanent magnetization and coercivity are comparatively smaller. The spinel MnZn ferrite nanosize powder was successfully prepared from δ-FeOOH at low temperature, with low-carbon steel and peroxide as main material.     

Analysis of Intermetallic Phases Formed on Surface Vapor Oxidized H13 Hot Work Steels in Molten Aluminum

In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample's cross-section shows that Fe3O4 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer),respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease.     

火焰原子吸收光谱法测定高纯石英粉中痕量钙

系统地研究了用空气——乙炔火焰原子吸收光谱分析法测定高纯石英粉中钙的最佳条件，建立了14％的乙醇作为增感剂，在2％盐酸介质中，0．4％ LaCl3溶液作为释放剂，用塞曼火焰原子吸收法测定的可行性方案，探讨了共存元素对钙的干扰及其消除。方法操作简便快速，干扰少，方法相对标准偏差小于3％，适用于日常分析石英粉中的杂质。     

有限元方法在离心机转鼓强度分析中的应用

在回顾以往转鼓强度分析的基础上 ,指出了目前转鼓有限元应力分析所存在的问题 ,给出了提高计算精度和保证模拟有效性的注意事项 ,并探讨了转鼓强度评定准则     

碳铵化肥发青问题解决小结

探讨了该厂化肥生产中碳铵发青的原因,通过硫化氢含量的测定,分析了系统内外影响因素,提出了解决措施,达到了不停车稳定产品质量的目的。     

海特隆酸不饱和聚酯树脂的性能及应用

叙述了海特隆酸不饱和聚酯树脂的特点和性能，并介绍其在湿氯气和其它氧化性介质中的应用。     

电除尘器出口烟气废热的利用

介绍了采用热管锅炉回收硫酸系统电除尘器出口烟气废热情况，可回收废热生产0．8MPa饱和蒸汽1．0t/h。通过严格控制饱和蒸汽压力、炉气的三氧化硫含量及入炉原料的水分含量，热管锅炉连续运行两年未发生泄漏。运行一年即可收回成本，经济效益显著。     

离子膜使用过程中起泡的原因及危害

分析并列举了离子交换膜在使用过程中鼓泡的原因，阳极液质量浓度；pH值；阴极液质量浓度；电流密度；开停车及盐水质量等因素都可以造成膜鼓泡，形成针孔。提出了相应的预防措施。     

Influence of Hydrostatic Pressure and Humidity on Superplastic Ductility of Two β-Spodumene Glass-Ceramics

The extent of superplastic deformation in two lithium aluminosilicate glass-ceramics was found to be limited either by intergranular cavitation or by the initiation and growth of surface cracks. Tensile tests were performed under a superimposed hydrostatic pressure to distinguish between the two failure mechanisms. Two materials, one with a high flow stress and the other with a low flow stress, were studied. Cavitation was substantially suppressed by hydrostatic pressure in both materials. The strain-to-fracture, however, was enhanced only in the material with the lower flow stress. (In at least one instance the tensile ductility became almost infinite.) In the material with the higher flow stress, failure was caused by the initiation and propagation of cracks from the surface. The crack-propagation mode of failure was found to be sensitive to humidity, raising the possibility of stress-corrosion cracking at high temperatures in glass-ceramic materials.     

冲击波和爆轰波的共异性

炸药爆炸是实现一些纳米新材料的重要能量来源之一。文章对炸药爆炸所涉及到的一些最基本的概念、模型及其基本关系及冲击波和爆轰波曲线的特征等做了一般性评述，旨在对纳米金刚石合成技术有所指导。