The Solidus Surface in the Ti ― Ni ― Hf System in the Ti ― TiNi ― HfNi ― Hf Region

Studies have been done on the phase equilibria at subsolidus temperatures in the Ti TiNi HfNi Hf region of the Ti Ni Hf ternary system. The phases based on binary compounds and solid solutions of these components are accompanied in the equilibria by a phase based on an equiatomic ternary compound. This new phase belongs to the family of Laves phases and has a hexagonal crystal structure of MgZn₂ type. The solidus surface in the Ti TiNi HfNi Hf subsystem consists of the surface of the ternary phase alone, the surfaces of the six solid solutions based on the components and binary intermediate phases, the planes of five conode triangles, and the corresponding lineated surfaces.     

Interactions in Molten Aluminum (Silicon) ― Boron Alloys

Isoperibolic calorimetry has been used to determine the partial and integral enthalpies of mixing for liquid alloys in the binary systems aluminum (silicon) boron at 1873 K. Those enthalpies are small exothermic quantities, which agree with published data. The enthalpies of mixing have also been calculated from the _f H ₂₉₈ of the metal borides. The concentration dependence has been determined for these enthalpies in binary alloys in the nontransition metal boron systems.     

Equilibrium Phase Diagrams for the Dy ― Al ― B and Er ― Al ― B Systems

X-ray diffraction has been applied to component interactions in order to construct isothermal sections of the phase diagrams for ternary systems Dy Al B at 600°C (region above 50 at.% Al) and 800°C (region below 50 at.% Al) and Er Al B at 800°C. It is confirmed that there are ternary borides: DyAl₃B> _x (structure type BaPb₃, space group R , a = 0.6156(3) nm, and c = 2.109(1) nm), DyAlB₁₄ (type MgAlB₁₄, Imma, a = 0.5819(2) nm, b = 1.0380(3) nm, c = 0.8176(5) nm), ErAlB₄ (type YCrB₄, Pbam, a = 0.59258(7) nm, b = 1.1515(2) nm, c = 0.35340(6) nm), and ErAlB₁₄ (type MgAlB₁₄, Imma, a = 0.5819(1) nm, b = 1.0401(2) nm, c = 0.8189(1) nm). The {Dy, Er} Al B systems lack signs of solid solutions based on binary and ternary compounds.     

Physico-Chemical Investigation of Component Interactions of the Si ― Al ― O ― N ― Ti System in the Region Si3N4 ― AlN ― Al2O3 ― SiO2 ― TiN ― TiO2. Part 1. Subsystems Si3N4 ― Al2O3, Si3N4 ― TiN,and Al2O3 ― TiN

Using the methods of differential thermal and x-ray diffraction analysis an investigation was made of component reactions in the Si Al O N Ti system, particularly between the compounds Si ₃N₄ Al₂O₃, Si₃N₄ TiN, and Al₂O TiN under conditions approximating those used in the hot pressing of composites. It was established that in the reaction of Si₃N₄ with Al₂O₃, -sialon, SiO₂, AlN, and the intermediate reaction products (mullite and X-phase) are formed. In the reaction of Si₃N₄ with TiN, as a result of the decomposition of Si₃N₄ at 1650-1900°C titanium disilicide is produced, which forms eutectics with free silicon and residual TiN at 1320 and 1280°C, respectively. The reaction of Al₂O₃ with TiN similarly leads to the formation of a eutectic between Al₂O₃ and spinel at 1850°C. The presence of eutectic liquids in the specimens after sintering promotes densification of the material, and improves certain of its mechanical properties.     

Cr(Ⅵ)与Cr(Ⅲ)的光度测定

本文研究了TnOA-H_2SO_4萃取分离、二苯偕肼显色光度测定微量Cr(Ⅵ)和Cr(Ⅲ),并满意地应用于工业废水的分析.用各种高分子胺萃取铬(Ⅵ)已早有报道,用TnOA从硫酸体系中萃取Cr(Ⅵ)亦有报道.为了消除干扰和富集铬,本文在前人工作的基础上研究了TnOA-H_2SO_4体系萃取分离、二苯偕肼显色光度测定微量Cr(Ⅵ)和Cr(Ⅲ)的适宜条件,并满意地应用于工业废水的分析.     

Thermodynamics of Component Interactions in Liquid Alloys of the Ternary Systems Ge(Al,Si) ― Ga ― Gd

The concentration dependence of the integral enthalpy of mixing in liquid alloys of the ternary systems Ge(Al, Si) Ga Gd at 1760 K, determined by the method of isoperibolic calorimetry and calculated using the surrounded atom model, was analyzed. Good agreement between H values obtained by both methods is noted. It was established that the interaction of gadolinium with components of the adjoining binary systems, which are characterized by the presence of intermetallic compounds, have a defining effect on the thermodynamics of alloy formation in the ternary systems Ge(Al, Si) Ga Gd.     

高纯Ta(OH)_5的生产

从纯的粗钽制取高纯Ta_2O_5的工艺为:(a)用含HF的酸性溶液(Ⅰ)以Ta-F络合物形式溶解粗钽;(b)以水不溶的有机溶剂(Ⅱa)和水不溶的季胺化合物(Ⅱb)的混合物(Ⅱ)从(a)溶液中萃取祖;(c)用至少合一种无机酸和(或)氨盐的水溶液(Ⅲ)洗涤有机相,以除去被萃取的杂     

Investigation of Liquid-Phase Sintering in W ― Sn ― Si Pseudoalloys

The kinetics of reaction between particles of tungsten and silicon during liquid-phase sintering of W Si Sn pseudoalloys was studied. Specimen growth caused by the formation of tungsten disilicide was observed. The growth rate in the investigated ranges of time and temperature obeyed a linear law. The rate constant was determined, and also the activation energy of the process, which agreed with the standard heat of formation of WSi₂.     

苯浮选Cr(Ⅲ)-二苯偶氮碳酰络合物光度法测定痕量Cr(Ⅵ)和Cr(Ⅲ)

在酸性条件下,Cr(能将二苯碳酰二肼(DPC)氧化成紫红色二苯偶氮碳酰,自身被还原为Cr(Ⅲ),Cr(Ⅲ)可与二苯偶氮碳酰生成深紫红色Cr(Ⅲ)-二苯偶氮碳酰络合物,该络合物在水相中不易溶解且不稳定,而在有机溶剂苯中稳定且极易溶解,用N2将Cr(Ⅲ)-二苯偶氮碳酰络合物浮选于苯中,形成真溶液,通过测定有机相吸光度测定溶液中Cr(含量。通过用过硫酸铵将溶液中Cr(Ⅲ)氧化成Cr(可测定Cr(和Cr(Ⅲ)合量(∑Cr),差减法计算出Cr(Ⅲ)含量。由于采用了大剂量富集倍数,使灵敏度大大提高,ε540=4.2×105,比水相光度法提高10倍。50 mL溶液中,Cr(质量线性范围0~12μg,测定5.0μg Cr(,RSD=1.8%(n=6),方法检出限7.1×10-9mol/L。由于络合和浮选的选择性,使本法选择性大大提高,实测了天然水中Cr(和Cr(Ⅲ),结果令人满意。     

The Equilibrium Phase Diagram for the Tm ― Mn ― B System

X-ray diffraction has been applied to the component interaction study in the ternary Tm Mn B system, and the 1070 K isothermal section of the phase diagram has been constructed. The ternary boride TmMnB₄ is confirmed as present, which has the YCrB₄ structure type (space group Pbam, a = 0.5868-0.5894 nm; b = 1.1320-1.1370 nm; c = 0.3368-0.34018 nm). The lattice parameter variation indicates that the ternary boride has only a narrow homogeneity region, which is in the direction of higher manganese contents. There are no solid solutions based on binary compounds in the Tm Mn B system.     

Regularities of Reactive Diffusion and Phase Formation in Ni ― Bi,Ni ― Zn,and Co ― Zn Binary Systems

Intermetallide layers enriched in bismuth or zinc are the first to grow in the Ni Bi, Ni Zn, and Co Zn reaction pairs. It is not found that high-symmetry phases of equiatomic composition are formed. There is not even a weak correlation between the rate of layer growth and the width of the homogeneity region for these intermetallic compounds. The main factors that determine the formation sequence for the intermetallic layers are the differences in melting point and atomic radius between the components, as well as the crystal structures of the intermetallides. The Kirkendall effect cannot be observed in the growing intermetallic layers. In that case, there is no physical basis for determining integrated diffusion coefficients.     

Nitriding Powders in the System SiO2 ― Al2O3 ― C

Chemical and x-ray analysis methods are used to study features of carbothermal reduction and simultaneous nitriding of a powder mixture of crystalline SiO₂ (α-quartz) and amorphous SiO₂ (Aerosil). It is established that the use of amorphous SiO₂ leads to accelerated formation of SiC and a shift in the direction of nitriding towards AlN formation. It is also shown that both phases are the solid solutions SiC ― AlN and AlN ― SiC.     

Study of Phase Formation Processes in the Systems Li ― N,Si3N4 ― Li3N,Si3N4 ― Li3N ― Y2O3

We have studied phase formation processes in the systems Li N and Si₃N₄ Li₃N. By nitriding lithium powder at temperatures of 400-600°C, we obtained lithium nitride Li₃N with a composition approaching stoichiometric. In the system Si₃N₄ Li₃N in the temperature range 300-1300°C, the ternary compounds Li₈SiN₄ (500°C), Li₅SiN₃, Li₂SiN₂ (900°C), and LiSi₂N₃ (1300°C) are formed. The studied properties of the hot-pressed composite material of the system Si₃N₄ Li₃N Y₂O₃ allow us to provisionally assign it to the class of solid electrolytes.     

少量添加Cr(Cr_3C_2)、Mo(Mo_2C)、Ta(TaC)的WC-10%Ni系非强磁性硬质合金粘结相的组成

研究了少量添加金属Cr、Mo、Ta及其碳化物的WC-10％Ni合金的磁性和粘绪相的关系,探讨了在何种粘结相成分下能得到非强磁性合金。其结果表明,由于粘结相中Cr和W同时大量固溶,不管合金碳含量如何,均形成非强磁性,另外,添加Mo(Mo_2C)、Ta(TaC)的合金与纯WC-Ni合金的机构大致相同,只有在减少碳含量,增加粘结相中W固溶量的条件下才能变为非强磁性。也证明了添加Cr(Cr_3C_2)的合金的室温强度在本质上比纯WC-Ni合金低。     

Subsurface Mobility of Organo–Cr(III) Complexes Formed during Biological Reduction of Cr(VI)

Hexavalent chromium [Cr(VI)] contamination of soil and groundwater is a major concern for some industrial sites as well as many United States Department of Energy sites. Bioreduction of Cr(VI) to less toxic and less mobile Cr(III) has received much attention as a viable method of remediation. However, bioreduction of Cr(VI) also produces soluble organo–Cr(III) complexes and little is known about the fate of these complexes in the environment. Cr(VI) was reduced abiotically in the presence of cellular organic compounds (malate, cysteine, and serine) and biotically in the presence of two test organisms (Cellulomonas ES6 and S. oneidensis MR1). The soluble organo–Cr(III) complexes formed were then introduced to soil columns to evaluate their sorption affinity and transport characteristics. The column data indicated that a significant fraction of the biologically derived organo–Cr(III) complexes are both soluble and mobile. Other complexes were observed to have limited mobility, indicating that a heterogeneous mixture of complexes are formed during biological reduction of Cr(VI).     

应用Cr(Ⅲ、Ⅵ)-CAS-CPB-NH_2OH·HCI-Zn(Ⅱ)体系分光光度测定Cr(Ⅲ、Ⅵ)

四川大学化学系方国祯等发现加入Zn(Ⅱ)可增加Cr(Ⅲ、Ⅵ)-CAS-CPB-NH_2OH·HCl体系的灵敏度并使最大吸收波长微移,Cr(Ⅲ)和Cr(Ⅵ)的分析数据几乎是相同的。指出在试验条件下铬的两种初始氧化态最终产生同样的氧化态Cr(Ⅲ)。Cr(Ⅲ、Ⅵ)-CAS-CPB-NH_2OH·HCl-Zn(Ⅱ)体系是高     

Phase Formation and Structure of Bronze ― Iron ― Graphite Composite Powder Material during Hot Forming

Copper tin iron graphite material prepared by hot forming is studied. It is established that on heating billets to 850°C Cu Sn alloy forms and there is no copper or tin in pure form after heating. The Fe Sn phase does not even form locally. Bronze grains have a banded relief that is connected with formation of a large number of twins and additional dislocations in Cu(Sn) solid solution. This structural inhomogeneity facilitates material strengthening and high operating properties.     

三正辛胺(TnOA)萃取Cr(Ⅵ)的机理研究

研究了用TnOAnCH3(CH2)6CH3H2SO4体系和TnOACHCl3H2SO4体系萃取Cr(Ⅵ)的机理及萃合物组成.考察了水相酸度,Cr(Ⅵ)、萃取剂与SO2-4浓度,萃取时间及温度等因素对萃取的影响.用饱和法、摩尔比法、等摩尔系列法和IR法确定了萃合物的组成和萃取平衡机理.结果表明,萃取过程属阴离子交换机理,萃合物的组成因pH值和c(Cr(Ⅵ))不同而异;pH值不同,Cr(Ⅵ)的型体也不一样;当c(TnOA)一定,pH=1.0,c(Cr2O2-7)=0.1000mol/L时,形成的萃合物是(R3NH)2Cr2O7(2∶1);当pH=-1.0,c(Cr2O2-7)=0.01945mol*L-1时,形成的萃合物是R3NHHCrO4(1∶1);SO2-4不被萃取,c(TnOA)及时间和温度对Cr(Ⅵ)的萃取影响不大.试验结果与Deptuta认为的Cr(Ⅵ)的型体为Cr2O2-7,Федоров和Жданов认为的Cr(Ⅵ)的萃取型体为CrO2-4的结论不同.     

5-Br-PADAP分光光度测定Cr(Ⅲ)

铬的测定,无论在钢铁分析还是在环境分析中都具有重要意义.二苯卡巴肼法是目前广泛用于钢铁等物质中铬的测定方法.该法灵敏度较高(ε_(540)=34600),选择性也较好.但是需将Cr(Ⅲ)氧化为Cr(Ⅵ)后再显色,而且显色剂本身稳定性差.最近十几年来,有人研究了Cr(Ⅲ)与PAN,PAR,铬菁R,二甲酚橙,偶氮胂Ⅲ等的显色反应.这些试剂灵敏度均较低,而且分析钢铁样品时,分离除去干扰离子的方法比较麻烦.2-[(5-溴-2-吡啶)偶氮]-5-(二乙基氨基苯酚)(简称5-Br-PADAP)是一种高灵敏的显色试剂.     

Bioceramics ― Yesterday,Today, Tomorrow

Developments and applications of bioceramics are reviewed. Used initially as alternatives to metallic materials in order to increase the biocompatibility of implants, bioceramics have become a diverse class of biomaterials presently including three basic types: bioinert high-strength ceramics; bioactive ceramics which form direct chemical bonds with bone or even with the soft tissue of a living organism; various bioresorbable ceramics which are actively included in the metabolic processes of an organism with predictable results. Certain members of the different types of bioceramics are the most bioinert and biocompatible of all known biomaterials. A review of the composition, physicochemical properties, and biological behavior of the principal types of bioceramic materials is given, based on the literature and some of our own data. The materials include, in addition to classical sintered ceramics, bioglass-ceramics and bioglasses which are similar in composition, properties, and applications. Special attention is given to structure as the main physical parameter determining not only the properties of the ceramic materials, but also their reaction with the biomedium. The present status of research and development in bioceramics is characterized as a first step in the solution of complex problems at the confluence of materials science, biology, and medicine by the synthesis of smart materials.