真空熔化法測定金属中的气体

溶解在金属中的气体,通常都是些有害的杂质,甚至重量仅为万分之几至百万分之几的含量,就足以破坏金属的机械性能。如锆中含氮从20ppm增至50ppm时,将显著降低其在600°F水中的抗腐蚀性,金属中的氢往往使金属变脆,铀中含氢达2ppm时,就会使抗张强度和延伸率降低。钢中高的残存氧量是危害钢铁质量的大敌。析出的某些类型的氧化物夹杂,使钢在热加工时发生“红脆”,并降低了塑性和强度;氧还改变了变压器钢的电工性能,减小了磁导率,提高了磁滞损失,自第二次世界大战后原子能、喷气飞机以及火箭等工业的发展,对高纯度、高质量的金属材料的要求特别迫切,因而准确快速的测定金属中的气体含量,以便在冶金过程中得以控制和消除,有其重大的意义。对于金属中氮、氢、氧三元素的测定,目前最广泛采用的是真空熔化法,本文拟把这方面的工作情况作一介绍。     

区域熔炼法制备高纯度金属

在电子工业生产中采用区域熔炼的方法 ,能将金属的纯度提高到 99 999999%。本文研究了区域熔炼的原理及实际应用等问题 ,并分别对含有杂质为KS>1,KS<1或同时含有KS>1和KS<1的金属的提纯作以详细分析     

络合吸附色层法纯制碱金属化合物的研究

制备高质量的荧光粉,首先要制得高纯度的原材料。制备高纯原材料,不仅要提纯基质材料,也要纯制助熔剂。碱金属化合物可用作发光材料的基质,也可用作助熔剂。因此有必要研究碱金属化合物的提纯,以除去其中对发光有害的杂质。使用络合吸附色层法来提纯发光材料是一种简单易行、生产效率较高的方法。     

反应气氛法纯制掺钕YAG混合粉料

本文介绍反应气氛法用于提纯Nd~(3+):YAG混合粉料。实验结果指出,在干燥O_2+I_2气氛中1350℃处理48h以上,能有效地除去Nd~(3+)+:YAG混合扮料中OH-杂质。用本法制得的混合料所生长的Nd~(3+):YAG激光晶体,提高了激光效率。     

用FeCl_3从复杂铋矿中浸出金属铋

从品位低、组成复杂、伴生钼、铜矿物的复杂铋矿石中浸出金属铋,采用常规搅拌浸出法在常温常压下进行浸出,讨论了酸度、FeCl3用量、浸出时间、浸出剂用量等对铋浸出率的影响。实验结果表明:用FeCl3浸出金属铋,铋的浸出率可达95%以上。     

纯2223相铋系超导体的合成

本文重点研究了铅含量，温度，出炉条件及气氛等因素对２２２３相的影响，得到了最佳合成工艺。     

纯金属中的玻璃形成

正如果冷却速度足够快,人们认为任何金属液体都可被冷凝成一种玻璃态,后者反过来又能产生具有不同寻常的、可能会有用的机械性能的一种固态金属。实践中,这种玻璃形成现象主要限于由两个或更多元素组成的金属:产生一种单原子金属玻璃所需的冷却速度通常太高,无法在实验中达到。Li Zhong等人找到了绕     

浮选分离-石墨炉原子吸收法测高纯镍中痕量铋

在硝酸钠存在下碘化钾-孔雀绿-水液-固体系浮选分离铋，采用石墨炉原子吸收法对高纯镍中痕量铋进行了分析。讨论并确定了实验的最佳测定条件。结果表明，Bi的检出限为1.9ng/mL。回收率为101.7%-102.5%，相对标准偏差（n=6)为1.1%-1.4%。方法已应用于高纯镍中痕量铋的测定。     

无溶剂结晶法纯制二苯醚

用无溶剂结晶法纯制二苯醚 ,该方法具有高效、经济和洁净的特点。用该方法制备得到的产品 ,其结晶点能由 2 6.5 5°C上升到 2 6.85°C以上 ,用国标方法检不出苯酚的含量 ,达到和超过进口产品的品质 ,从而达到制备具有高结晶点、低酚含量二苯醚的目的。     

区域熔融法提纯工业黄磷的数学模型与实验研究

为了满足高纯磷酸以及半导体等行业对高纯磷的需求,采用了区域熔融法对工业黄磷进行提纯,分析了区熔法提纯工业黄磷的原理,并根据所测有效分布系数建立整个区熔过程中杂质分布的数学模型.实验考察了熔区长度以及熔区移动次数等对杂质分布的影响,研究结果表明,采用区域熔融法提纯黄磷具有良好的效果,能有效地脱除所考察的13种杂质(Fe, Ca, Co, Mg, Cr, Cd, Mn, Ni, Cu, Pb, Zn, Al, As);当熔区为区熔管长度的0.1倍时,熔区移动速度为5 mm·h~(-1),经过10次区熔后,60%的黄磷产品纯度达到99.99999%(7N),完全能够满足半导体行业以及高纯磷酸对磷的纯度要求;所建立的杂质分布数学模型能够很好地描述杂质在区熔过程中的分布情况.     

Processing of Metallic Bismuth with the Production of Bismuth Oxohydroxotribromophenolate

The hydrolytic processing of metallic bismuth with the production of bismuth oxohydroxotribromophenolate pharmacopeial composition [Bi₆O₆(OH)₂](C₆H₂Br₃O)₄ used to prepare the medical drug Xeroform was studied by chemical, X-ray diffraction, and thermogravimetric analyses and electron microscopy. The results of these studies were confirmed by the industrial tests of the developed technology based on the oxidation of metallic bismuth, the dissolution of synthesized technical oxide in nitric acid, the hydrolytic purification of bismuth from impurity metals by aqueous alkaline hydrolysis with the precipitation of bismuth in the form of oxohydroxonitrate [Bi₆O₄(OH)₄](NO₃)₆?H₂O, the dissolution of bismuth oxohydroxonitrate in nitric acid, and the synthesis of bismuth oxohydroxotribromophenolate by adding an aqueous sodium tribromophenolate solution to the resulting solution in the presence of sodium acetate at a pH of 6.5–7.5 and a temperature of 90–95°C.

     

Processing Metallic Bismuth to Produce Citrate

Theoretical Foundations of Chemical Engineering - Using chemical and XRD phase analysis, along with electron microscopy, the hydrolytic processing of metallic bismuth into high-purity citrate has...     

Probability of Trapping Solid Particles during Zone Melting

Abstract

The probability P of trapping of glass beads was measured for tilt rotating zone melting of camphor. P increased with increasing zone travel rate, increasing tilt angle, decreasing tube rotation, and increasing mass of beads. P also decreased dramatically with distance down the tube. This is attributed to increasing impurity content as the zone moves down the tube and by the changing shape of the freezing interface due to the diminished content of glass beads. Trapping was predominantly by periodic bands, indicating one or more catastrophic trapping mechanisms.     

硅石焙烧-酸浸提纯及杂质相结构的演变

在硅石提纯过程中,采用XRD和EDS分析硅石中杂质元素赋存特征,采用高温焙烧活化与酸浸复合提纯方法研究了酸浸过程杂质相结构演变及提纯效果. 结果表明,硅石中不同类型铝硅酸盐的K, Na, Ca, Al, Si含量不同,主要分为长石类、伊利石和高岭石;酸浸提纯过程中硅石的杂质相不仅会溶解在酸中,且长石类杂质相会演变成伊利石和高岭石. 与未预酸浸的硅石提纯相比,预酸浸的硅石经高温焙烧活化提纯后纯度达99.995%,达到高纯石英砂的纯度,杂质Al和K含量分别降低了76.6%和66.5%;在700℃下焙烧,预酸浸硅石的Al和K去除效果最好,去除率分别为85%和41%.     

Influence of Localized Melting on Dynamic Fracture Behaviours of Metallic Shell

The dynamic fracture behaviour of cylindrical shell preformed by localized melting technology was studied experimentally, and the microstructure and performance of melted layers were also analyzed in this paper. The results reveal that the microstructure of melted layer is predominantly needle type and refined martensite by the melted‐solidification process. With the increase of hardness and decrease of impact energy absorbed, the embrittlement tendency of localized melting sample is obviously. Compared with natural fragmentation, the fragments of shell after melting are more regular, and the proportion of effective fragments is high. Due to the sensitivity of shear bands of melted layers, fracture can easily take place along the melting trajectory subjected to internal explosive loading.     

Purification of Tin by a New Method of Zone Refining

Abstract

The purification of tin by a new method of zone refining is described. The method is characterized by alternating high-speed clockwise and anticlockwise rotations (0 to 3000 rpm) of the containing tube at short intervals (0.5 to 10 sec). The experimental parameters which affect the degree of purification were investigated in some detail. The concentration of major impurities was lowered by about two orders of magnitude by 20 zone passes under standard operating conditions.     

Comparison of Yield for Zone Melting and Progressive Freezing

Abstract

The conditions under which the yield of purified product is identical for progressive freezing and zone melting have been determined. When the distribution coefficient is less than 1, the yield of progressive freezing is increased by lowering the amount of material rejected after each operation. When the distribution coefficient is greater than 1, however, the usual zone-melting conditions result in a greater yield than is possible with progressive freezing.     

沟槽机筒单螺杆挤出机耦合双槽熔融理论研究

利用自制的液压剖分式沟槽机筒单螺杆挤出机实验平台,研究了沟槽机筒单螺杆挤出机的熔融长度和螺杆转速的关系,实验验证了单螺杆挤出机固体输送段和熔融段机筒均开设沟槽的耦合双槽熔融理论。结果表明,与传统光滑机筒单螺杆挤出机和IKV单螺杆挤出机相比,在熔融段机筒开设沟槽的单螺杆挤出机的熔融长度较短且熔融过程比较稳定,熔融效率得到较大提高。