Determination of Oxide in FLINAK Melt by Electrochemical Titration Technique

The use of K_2NbF_7 as a probe solute for the cyclic voltammetric determination of oxide in FLINAKmelts was studied and demonstrated.This method is based on a complex reaction and the peak current densityof NbF_7~(2-)reduction.The reaction constant was determined to be very large at 973 K.A cyclic voltammetricstandard addition experiment is also employed to determine the amount of oxide in FLINAK melt.The oxidecontent of FLINAK melts is equal to the amount of Nb(V)added minus the amount of NbF_7~(2-)which is ob-tained from the voltammogram.     

高苛性比铝酸钠溶液的Raman光谱研究SCIEI

用 Raman光谱方法研究高苛性比铝酸钠溶液的阴离子组成.高苛性比的铝酸钠溶液的Raman光谱在470cm^(-1)等处有特征峰.和固体Ca_3[Al(0H)_6]_2及Ba_2[Al_2-(OH)_(10)]的 Raman谱相对照,可看出高苛性比的浓铝酸钠溶液可能含有Al(OH))_6^(3-)及其聚合离子。     

THE DESULPHURIZATION OF MOLTEN SLAGS IN THE GASEOUS PHASE DURING TOP-BLOWN WITH AIR

利用空气顶吹研究熔渣的气态脫硫动力学,着重研究了熔渣∑FeO含量、j值[j=N_(Fe_2O_3)/(N_(Fe_2O_3)+N_(FeO))]、以及碱度对气态脫硫速度的影响.对气态脫硫反应的机理及反应速度的限制性环节作了分析和讨论.最后,对金属直接的气态脫硫、炉渣的气态脫硫和炉渣脫硫本身的矛盾、以及气态脫碗在转炉炼钢工艺上的应用问题进行了简要的讨论.     

硼酸盐缓蚀作用机理的研究——对缓蚀过程中溶解氧作用的新见解

采用腐蚀失重法、电位-时间曲线、极化曲线、划伤电极技术、赤血盐显色试验及XPS等方法,研究了硼砂对碳钢的全面腐蚀与孔蚀的缓蚀作用与机理。结果发现,硼砂对碳钢的缓蚀作用并不依赖于溶解氧的存在,而且随溶解氧浓度的增加.其缓蚀率、抗孔蚀及Cl~-侵蚀的能力,以及膜的修复能力下降。在有溶解氧存在的条件下,硼砂在碳钢表面所形成的保护膜的主要组成是FeO、Fe2_O_3与铁的硼酸盐,并夹杂有Cl-,硼砂表现出阳极抑制型缓蚀剂的特性;在脱氧的条件下.膜的主要组成是在微薄的FeO、Fe_2O_3膜上吸附B_4O_1~(2-)离子,硼砂表现出混合抑制型缓蚀剂的特征。     

几种含铌镍基合金的热腐蚀研究

用硫酸钠沉积法研究了四种镍基合金-Ni-16Cr,Ni-16Cr-2Nb,IN738和537合金-在900～1000℃之间的热腐蚀行为。用热天平测量了热腐蚀动力学曲线,用金相、SEM、电子探针、X 射线衍射和~(3δ)S 示踪法观察和分析了腐蚀产物。研究发现,Ni-16Cr-2Nb 合金中的铌富集在表面氧化膜内,形成 NaNbO_3而降低熔盐中的 O~(2-)浓度,抑制 Cr_2O_3膜与熔盐的反应;但在复杂成份的合金中。铌的上述作用可能促进氧化膜的酸性熔融。鈪同时能促进硫在 Ni-16Cr-2Nb 变形合金晶界上的连续分布,加速内硫化过程。     

Existing form of Mo(Ⅵ) in acidic sulfate solution

The existing form of molybdenum in acidic sulfate solution was studied by means of ion exchange,infrared(IR) spectra and X-ray photoelectron spectroscopy(XPS).The results indicate that the anionic molybdenum species are predominant in acidic sulfate solution,and Mo(VI) can combine with sulfate radical to form heteropoly acid anions[Mo_2O_5(SO_4)_2]~(2-) and[MoO_2(HSO_4)_4]~(2-).With the decrease in solution pH from 1.92 to 0.06,the existing form of Mo(VI) changes from Mo_7O_(21)(OH)_3~(3-) to[Mo_2O_5(SO_4)_2]~(2-) and then becomes[MoO_2(HSO_4)_4]~(2-),which results in the decrease in the resin adsorption capacity for molybdenum.     

新型TiNbTaZr合金的生物腐蚀性和细胞毒性(英文)

通过真空自耗电弧炉开发一种新型β钛合金Ti35Nb2Ta3Zr,其弹性模量仅为48GPa,探讨该合金的耐腐蚀性能和细胞毒性。在Ringer模拟体液中,通过测量开路电位、极化阻抗谱和极化曲线发现Ti35Nb2Ta3Zr的腐蚀性优于Ti6Al4V和Ti。细胞毒性试验证明Ti35Nb2Ta3Zr的生物相容性与目前临床常用的Ti6Al4V和Ti相当。因此,该新型β钛合金Ti35Nb2Ta3Zr具有良好的耐腐蚀性和生物相容性,未来作为生物材料具有广阔前景。     

镍基高温合金M17和M38G的电化学腐蚀行为研究

采用电化学方法、扫描电镜、能谱分析等技术,研究了常温下镍基高温合金M17和M38G在NaCl溶液和含S2O2-3的NaCl溶液中的腐蚀行为.结果表明,在含质量分数为3.5% NaCl的溶液中,M17和M38G均会遭受严重的点腐蚀;向NaCl溶液(NaCl质量分数为3.5%)添加Na2S2O3(Na2S2O3质量分数为1.5%)后,由于溶液中的S2O2-3在试样表面活性点与Cl-竞争吸附并与H 结合,使两种合金的点蚀均受到抑制;M38G中存在微量的Nb、Ta、Mo等元素使得M38G合金在NaCl溶液中的耐腐蚀性能明显优于M17合金.     

EQUILIBRIA OF Sr,Ba AND O,S IN LIQUID Fe

The equilibrium constants between Sr-O,Ba-O and Sr-S,Ba-S in liquid iron at 1570℃ and the interaction coefficients concerning these elements have been determined as follows: K_(Sro)=1.897×10~(-7),e_O~(Sr)=-43.8 K_(BaO)=8.204×10~(-8),e_O~(Ba)=-98.0 K_(SrS)=8.356×10~(-7),e_S~(Sr)=-3.9 K_(BaS)=4.083×10~(-7),e_S~(Ba)=-3.5     

CaBi_4Ti_4O_(15)高温无铅压电陶瓷的B位高价掺杂改性研究

分别以V~(5+)、Nb~(5+)和W~(6+)离子对CaBi_4Ti_4O_(15)陶瓷进行B位取代,比较3种掺杂离子对CaBi_4Ti_4O_(15)陶瓷的烧结、介电和压电性能的影响.结果表明:3种离子的掺杂均能改善材料的烧结特性,提高瓷体致密度,同时降低高温电导率和损耗.V~(5+)掺杂可显著改善烧结性能,少量V~(5+)掺杂对居里温度影响不大,但可显著降低高温电导率和高温介电损耗.少量Nb~(5+)掺杂可有效提高材料的压电性能.W~(6+)掺杂对居里温度影响最为显著,使居里温度降低了30 ℃,但改性效果不如Nb~(5+)和V~(5+)明显.     

Electrochemical characteristics of titanium based biomaterials in artificial saliva

In the last decade, new titanium alloys have been developed in different areas of dentistry, such as Ti6Al7Nb, Ti6Al2Nb1Ta1Nb, and Ti5Al2.5Fe. The aim of this study was to compare the Ti6Al7Nb, Ti6Al2Nb1Ta1Nb, Ti5Al2.5Fe, and Ti6Al4V alloys with the commercial titanium, regarding the corrosion resistance in artificial saliva. In the electrochemical estimations the polarization data are converted into instantaneous corrosion rate values (I_corr). The passivation properties were comparable for the four alloys. The EIS spectra are best fitted using an equivalent circuit (EC), which corresponds to the model of a two‐layer structure for the passive film. High impedance values (in the order of 10⁶ Ω cm²) were obtained from medium to low frequencies for all materials suggesting high corrosion resistance in artificial saliva. The electrochemical and corrosion behavior of Ti6Al4V is not affected on substituting vanadium with niobium, iron, molybdenum, and tantalum.     

In vitro corrosion resistance and cytotoxicity of novel TiNbTaZr alloy

A novel β type Ti35Nb2Ta3Zr alloy with low modulus (48 GPa) was fabricated using vacuum consumable arc melting. The corrosion resistance and cytotoxicity of Ti35Nb2Ta3Zr were evaluated. The open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods were used to determine the corrosion resistance. In Ringer's solution, Ti35Nb2Ta3Zr alloy exhibits better corrosion resistance, as compared to that of Ti6Al4V and Ti. The cytotoxicity tests indicate that the biocompatibility of Ti35Nb2Ta3Zr is as good as Ti and Ti6Al4V which are widely used in biomedical fields. Based on corrosion resistance and cytotoxicity, the novel β type Ti35Nb2Ta3Zr alloy can be considered as a potential biomaterial.     

Bonding of Al2O3 ceramic and Nb using transient liquid phase brazing

The brazing of Al2O3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni-5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1423-1573 K for 1-120 min. The results show that the shear strength of the joint first increases and then decreases with increasing holding time and brazing temperature. The joint interface microstructure and elements distribution were investigated. It can be concluded that a composite structure, in which the base metals are solid solution Nb(V) and Nb(Ti) reinforced by Ni3Ti, is formed when the brazing temperature is 1473 K and holding time 15 min, and a satisfactory joint strength can be achieved. The interaction of Ti foil and Ni-5V foil leads to the formation of liquid eutectic phase with low melting point, at the same time the combination of Ti come from the interlayer with O atoms from Al2O3 results in the bonding of Al2O3 and Nb.     

Adsorption of Ag（Ⅰ） on H2TiO3 from aqueous solutions

Adsorption of silver ions from aqueous solution onto H2TiO3 was studied. Equilibrium experimental studies were performed to determine the adsorption capacity of H2TiO3 for silver ion at various pH values. Batch experiments were conducted in the range of pH value 3-7 and silver ions concentration 10-200 mg/L. The results show that the adsorption is strongly dependent on pH value. The equilibrium absorption capacity of H2TiO3 increases significantly with the increase of pH value from 3 to 7. The adsorption of silver ion obeys the Langmuir isothermal equation well in the concentration range studied, the adsorption constant is 0.054 7, 0.052 4, 0.0881 at pH 5, 6 and 7, respectively, and the maximum adsorption capacities are 23.64, 29.76 and 40.82 mg/g.     

碱热处理对TC4合金微弧氧化膜生物活性的影响

利用微弧氧化技术在Ti6Al4V合金表面制备含钙、磷的多孔TiO_2涂层(记为MAO),并对涂层进行碱热处理(记为MAONH).结果表明:MAONH膜层的相结构和MAO膜层的大有不同,它主要由TiO_2(金红石型和锐钛矿型)、钛酸钙相组成.钙和磷离子在MAONH膜层表面比在MAO膜层表面更容易沉积,其原因是钛酸钙在模拟体液浸泡时发生水解,生成大量的Ca~(2+)和OH~- 离子,Na~+和OH~-离子同模拟体液中的Ca~(2+)和PO_4~(3-)离子发生离子交换,导致磷灰石在MAONH膜层表面沉积.     

Surface characterization of passive film formed on nitrogen ion implanted Ti-6Al-4V and Ti-6Al-7Nb alloys using SIMS

The aim of this paper is to study the effect of N⁺ ion implantation on corrosion and phase formation on the implanted surfaces of Ti-6Al-4V and Ti-6Al-7Nb alloys. Nitrogen ion was implanted on Ti-6Al-4V and Ti-6Al-7Nb alloys at an energy of 70 and 100 keV, respectively using a 150 keV accelerator at different doses ranging from 5 × 10¹⁵ to 2.5 × 10¹⁷ ions/cm². Electrochemical studies have been carried out in Ringer’s solution in order to determine the optimum dose that can give good corrosion resistance in a simulated body fluid condition. The implanted surfaces of such modified doses were electrochemically passivated at 1.0 V for an hour. Secondary ion mass spectroscopy was used to study and characterize titanium oxide and titanium nitride layers produced on implanted surface and to correlate them with the corrosion resistance. The nature of the passive film of the implanted-passivated specimen was compared with the unimplanted-passivated as well as as-implanted specimens.     

Composition and processing effects on the electrochemical characteristics of biomedical titanium alloys

The electrochemical behaviour of the Ti–13Nb–13Zr and Ti–6Al–4V ELI alloys with martensitic microstructures was investigated by polarization and electrochemical impedance spectroscopy (EIS) in Ringer’s solution. The impedance spectra were interpreted by a two time-constants equivalent circuit. Both investigated alloys showed high corrosion resistance, but the thin and uniform passive film on the Ti–6Al–4V ELI alloy surface was more protective. The inner barrier and outer porous layer were highly resistant and capacitive. However, thicker and more porous passive film on the Ti–13Nb–13Zr alloy surface may be beneficial for osteointegration. The suitable thermomechanical processing improved the corrosion resistance of Ti–13Nb–13Zr alloy.     

Electrochemical impedance spectroscopic studies of titanium and its alloys in saline medium

The influence of potential on electrochemical behaviour of pure Ti, Ti‐6Al‐7Nb, and Ti‐6Al‐4V ELI alloy under saline conditions were investigated by electrochemical impedance spectroscopy (EIS). All measurements were carried out in saline solution (0.9% NaCl) at different impressed potentials (corrosion potential (E_corr), 0 mV (SCE) and + 500 mV (SCE)) for 1 h. The experimental results were compared with those obtained by potentiodynamic polarization curves. The corrosion current densities obtained for the titanium alloys showed lower values than for pure Ti, indicating the formation of a stable passive film with time. Electrochemical impedance spectroscopic studies indicated that the resistance of the passive film increased with the impressed potential. The impedance spectra were fitted using a non‐linear least square (NLLS) fitting procedure. The magnitude of the corrosion resistance of titanium alloys under saline solution was compared and results are presented.     

铜钴镍离子对镁合金微弧氧化膜的影响

目的提高镁合金微弧氧化膜的耐蚀性。方法在Na_2SiO_3-NaOH-Na_2B_4O_7组成的电解液体系中,分别加入铜离子、钴离子和镍离子对AZ91D镁合金进行微弧氧化,研究离子种类和组成对膜层性能的影响。采用点滴实验测试膜层的耐蚀性,采用电化学工作站测试膜层的电化学性能,采用扫描电子显微镜(SEM)和能谱分析(EDS)对微弧氧化膜层的表面形貌和元素组成进行分析。结果电解溶液中加入钴离子、铜离子、镍离子后,镁合金微弧氧化膜的耐腐蚀性能均有提高。其中铜离子的影响最大,加入1.5 g/L的铜离子后,镁合金微弧氧化膜的点滴时间提高了77.3 s,膜层耐腐蚀性能显著提高。电化学测试结果得出,不加金属离子的氧化膜的腐蚀电流密度为1.092×10~(-5) A/cm~2,腐蚀电位为-1.487 V;加入钴、铜、镍离子浓度分别为2、1.5、3 mol/L时,腐蚀电流密度分别为3.912×10~(-6)、6.027×10~(-6)、2.167×10~(-6) A/cm~2,腐蚀电位分别为-1.412、-0.832、-1.047 V;加入金属离子制得的微弧氧化膜的腐蚀电流密度均降低了1个数量级,腐蚀电位不同程度地正移,其中加入铜离子后腐蚀电位提高了0.655 V。加入金属离子后,陶瓷膜表面空隙和孔洞数量不同程度地变浅和减少,增加了膜层的致密性和均匀性。结论电解液中添加一定量的铜、钴、镍离子均能够提高AZ91D镁合金微弧氧化膜层的耐蚀性,其中铜离子的效果最明显。     

用钒(V)-PAR-NH_2OH-DDMAA混合显色体系测定钒

研究了钒(V)-PAR-羟胺-DDMAA(Dodecyldimethylamino acetic acid)混合显色配位体系的特性.该体系在0.5～0.9mol/L硫酸溶液介质中,其最大吸收峰λ_(max)为560nm波长处,在560nm波长处空白值几乎等于零,摩尔吸光系数∈_560为3.7× 10~4L·mol~(-1)·cm~(-1).配合物的组成比,V(v):PAR:NH_2OH:DDMAA为1:1:1:1:1.0～30μgV~(5+)+/25ml范围内.服从比尔定律,用该方法直接测定钨精矿和钨矿中微量钒,获得了满意的结果.