THE STRUCTURE CONTROL OF ALUMINUM FOAMS PRODUCED BY POWDER COMPACTED FOAMING PROCESS

A new technique, powder compact foaming process for the production of aluminum foams has been studied in this article. According to this method, the aluminum powder is mixed with a powder foaming agent (Till2). Subsequent to mixing, the powder blend is hot compacted to obtain a dense semi-finished product. Upon heating to temperatures within the range of the melting point, the foaming agent decomposes to evolve gas and the semi-finished product expands into a porous cellular aluminum. Foaming process is the key in this method. Based on experiments, the foaming characteristics were mainly analyzed and discussed. Experiments show that the aluminum-foam with closed pores and a uniform cell structure of high porosity can be obtained using this method by adjusting the foaming parameters: the content of foaming agent and foaming temperature.     

EFFECT OF FINE GRINDING ACTIVATION ON LEACHING BEHAVIOUR OF SCHEELITE CONCENTRATE

The influence of mechanical activation on the leaching behaviour of scheelite was studied bymeans of fine grinding in an attritor and subsequently HCl leaching in presence of PO_4~(3-).Results showed that after fine grinding in the attritor,the reaction rate of scheelitewith HCl-Na_3PO_4 solution was remarkably increased,the extraction of W increased fromabout 8 to 99%.The IR spectra and X-ray diffraction analysis indicated that in addition toan enlargement of surface area the fine grinding action had made also changes of fine struc-ture and reactivity of solid surface,hence the leaching process of scheelite can be carried outunder mild leaching conditions.     

相尺寸和铁添加剂对W—Cu（20wt％）复合粉末烧结行为的影响

研究了钨-20％铜(W-20wt％Cu)复合粉末中相尺寸和少量铁对烧结行为的影响。两种混合粉末分别由湿法冶金(H)或机械合金化(M)合成。机械合金化粉末由纳米级W—Cu混合物和微米级W和Cu晶粒组成。不合Fe和掺杂0．2wt％Fe的湿法冶金粉的相尺寸为150nm-450nm。加热和在10900C—1250℃(3min～80min)下处理后的相对密度对烧结进行了研究。粒度较粗的纯的湿法冶金粉压坯烧结获得了最低密度(88％)：较小的相尺寸或Fe添加剂增加烧结的密度。纯细和掺杂的粗湿法冶金粉达到了最高密度(96％一98％)。Fe添加剂显著降低了导电性。     

工业纯钛在不同温度下的屈服应力应变

前言晶粒度、杂质含量、应变速率和试验温度都影响工业纯钛的屈服点。如果晶粒度小于50微米,在室温下就可观测到上屈服点和下屈服点。屈服落差随钛中氧和氮的含量而增加。     

梁赞有色冶金工厂采用钛装置

在梁赞有色冶金工厂的主要工序中采用了含硫酸盐和金属氟化物杂质的硫酸腐蚀溶液,气体含硫化物,氟化物和二氧化碳,氟,氯以及硫酸蒸气。由于材料快速腐蚀破坏,所用装置的工作寿命不长。在某些工序中应用钛制装置可以延长其使用寿命,降低生产消耗,强化工艺过程。在湿法冶金,微尘回收和配料干燥车间所进行的、BT1—0、BT5—1钛合金与X18H10T、X17H13M2T钢的对比腐蚀试验(见表)表明:在大多数研究介质中     

Ti5Nb人工钉扎中心NbTi超导体的磁通钉扎机制分析

采用棒基组合的装配方法，用热挤压和冷加工相结合的工艺制备了岛状Ti5Nb人工钉扎中心NbTi超导体，其中Ti5Nb体积含量为10％。通过对此超导体进行详细的磁通钉扎机制分析，认为样品的磁通钉扎力特征主要由正常相钉扎和Δκ扎相结合的机制决定。根据分析的结果，采用多源标度方法，很好地拟合了不同线径样品的磁通钉扎力密度随磁场变化的曲线。拟合的结果表明：样品在较低场下的性能主要由正常相钉扎机制决定，而在较高场下的性能主要由Δκ钉扎机制决定。并且随着线径的减小，正常相钉扎力密度和Δκ钉扎力密度均有不同程度的提高。     

磁带的湿老化动力学

本文主要描述了磁带用聚酯型聚氨酯粘合剂的水解动力学。动力学数据是由检测不同湿-温度环境下粘合剂水解产物的丙酮萃取物与其水解时间的关系曲线得到的。这些数据可以由线性、单一产品的可逆速率方程来描述.该方程与检测水解对已记录磁带的性能影响均可用来预测磁带合适的环境贮存条件.     

Rationally designed inhibitors as tools for comparing the mechanism of squalene-hopene cyclase with oxidosqualene cyclase

The inhibition of squalene-hopene cyclase (SHC) (E.C. 5.4.99.-), an enzyme of bacterial membranes catalyzing the formation of pentacyclic sterol-like triterpenes, was studied by using different classes of compounds originally developed as inhibitors of oxidosqualene cyclase (OCS) (E.C. 5.4.99.7), the enzyme of eukaryotes responsible for the formation of tetracyclic precursors of sterols. The mechanism of cyclization of squalene by SHC, beginning with a protonation of the 2,3 double bond by an acidic residue of the enzyme, followed by a series of electrophilic additions of the carbocationic intermediates to the double bonds, is similar to the mechanism of cyclization of 2,3-oxidosqualene by OSC. The inhibitors studied included: (i) analogs of the carbocationic intermediates formed during cyclization, such as aza-analogs of squalene and 2,3-oxidosqualene; (ii) affinity-labeling inhibitors bearing a methylidene reactive group; and (iii) vinyldioxidosqualenes and vinylsulfide derivatives of the substrates. Comparison of the results obtained with the two enzymes, SHC and OSC, showed that many of the most effective inhibitors of OSC were also able to inhibit SHC, while some derivatives acted as specific inhibitors. Differences could be easily explained on the basis of the different substrate specificity of the two enzymes.     

中微孔复合分子筛的合成研究开发进展

综述了复全分子筛合成的研究进展，介绍了原位合成法，离子交换法和纳米组装法。分析比较了各种合成方法的特点，讨论了方法的适用范围，指出复合分子筛的合成中存在的一些问题，认为合成具有大－中－小孔梯度分布的复合物和用硅铝纳米簇进行自组装合成中孔材料将是今后发展的主流。     

尼龙及超细尼龙专用活性染料-ERIOFAST

Eriofast是亨斯迈纺织染化部专门为尼龙及超细尼龙染色而并发的专用活性染料.本文除了叙述Eriofast活性染料开发的背景外,还阐明了使用与其相匹配而专用的Eriofast Fix交链剂的优点,尤其突出的是在染色工艺中使用氯化钙可以在全消光的聚酰胺纤维上获得很深的色相.