密闭消解-ICP-MS法测定地质样品中的痕量铑和铱

采用密闭消解的方法,以王水在200℃经16 h消解地质样品,用电感耦合等离子体质谱法(ICP-MS)直接测定Rh和Ir。以Lu为内标元素消除基体效应,建立校正方程消除Cu和Sr对Rh、Hf对Ir的所产生的多原子离子干扰,可在酸溶体系中不经分离富集直接测定铂族物料中的痕量Rh和Ir。结果表明,Rh和Ir的检出限分别为0.014 ng/g和0.012 ng/g,方法回收率为90%~111%,用于铂族元素地球化学一级标准物质中Rh、Ir的测定,所得结果与认定值一致,相对标准偏差(RSD)小于9.6%。     

ICP-AES测定银内胆水杯中有害元素迁移量

建立了一种基于电感耦合等离子体原子发射光谱法(ICP-AES)测定银内胆水杯中6种有害元素(砷、镉、铬、镍、铅和锑)迁移量的方法。结果表明，待测元素在标准曲线浓度范围内均呈良好线性关系，加标回收率86.1%~103.3%，相对标准偏差(RSD)均小于5%。在酸性迁移条件下，部分样品可检出一定量的锑元素迁移量，锑迁移量为0.00868~0.0304 mg/dm²。可为银餐具安全评价提供技术支持。     

DDO-锑粉沉淀富集铬铁矿中微量铂族元素

铬铁矿中分析铂族元素分干法和湿法。干法以[预处理锍试金光谱法]较好。但试金中产生新铬铁矿造成捕收损失,且酸溶产生“闪光物”,使分析难于进行。湿法则先将锇钌蒸出,然后沉淀铂钯铑铱。分步富集,流程冗长。DDO 作铂族组沉淀剂,本所1973年提出实验。资料有锑粉置换分离铑铱的介绍。     

密闭消解-重量法测定掺铱、锇和钌的黄金饰品中金量

掺杂铱、锇和钌的黄金饰品中金的量难于用密度法或X射线荧光光谱法(XRF)测定。将样品在高压密闭条件下经过王水消解后,掺杂的难溶金属可过滤分离,以80%水合肼(用水稀释6倍)作还原剂,将滤液中的金还原成沉淀,以重量法测定金含量,金粒的纯度用火花原子发射光谱法测定。方法加标回收率为96.2%~101.6%,相对标准偏差(RSD,n=6)为0.09%~0.23%,可满足掺杂铱、锇和钌的黄金饰品中金的测定。     

四(亚硝基)合钯酸钾的合成、单晶结构及其循环伏安特征

以醋酸钯(PdAc2)与亚硝酸钾(KNO2)为起始原料，水为溶剂，合成四亚硝基钯酸钾(K2[Pd(NO2)4])，产率为96.5%。采用溶剂挥发法培养出其单晶，经X射线单晶衍射分析证实:此晶体由中心对称的[Pd(NO2)4]^2-配阴离子，K⁺阳离子和2分子结晶水组成，为三斜晶系，P-1空间群，晶胞参数为:a=6.4953(5) nm，b=7.0134(5) nm，c=7.1473(5) nm，α=118.784(2)°，β=101.050(2)°，γ=98.085(2)°，Z=1，Pd-N键长为2.014 nm和2.037 nm，∠N-Pd-N为91.70(4)°，且Pd²⁺位于4个N原子组成的平面四边形的中心。采用恒电位仪在室温下测试其循环伏安图，测得其还原峰电位(Ep)为-0.51 V (vs. SCE)。     

纳米锑掺杂对回流焊Sn-3.0Ag-0.5Cu-xSb焊点界面IMC生长的影响机理

研究了纳米锑掺杂对回流焊过程中Sn-3.0Ag-0.5Cu-xSb(x=0,0.2%,1.0%和2.0%)焊点界面金属间化合物(IMC)生长动力学的影响.借助扫描电镜(SEM)观察了焊点的微观结构,利用X射线能谱分析(EDX)及X射线衍射谱仪(XRD)确定了IMC的相和成分.结果表明,部分纳米锑颗粒溶解在富锡相中形成SnSb二元相,部分纳米锑颗粒溶解在Ag₃Sn相中形成Ag₃Sb相,剩余部分沉降在界面Cu₆Sn₅金属间化合物层表面.随着纳米锑含量的增加,IMC厚度减小.当纳米锑的含量为1.0%时,IMC厚度最小.通过曲线拟合,确定出界面IMC层生长指数和扩散系数.结果表明,IMC层生长指数和扩散系数均随着纳米锑含量的增加而减小.当纳米锑的含量为1.0%,IMC层生长指数和扩散系数均有最小值,分别为0.326和10.31×10^-10 cm²/s.由热力学相图和吸附理论可知,Sn,Sb元素之间易形成SnSb化合物,引起Sn元素的活性、Cu-Sn金属间化合物形成的驱动力和界面自由能下降,从而导致Cu₆Sn₅金属间化合物生长速率下降,抑制IMC生长.     

铋试金﹣二次灰吹﹣ICP-AES测定黑色岩中的铂、钯、金

黑色岩中的大量碳、硫、镍影响铋试金的捕集和操作。在铋试金配料中加入硝酸钾、铁粉、硝酸银和亚碲酸钾,可消除碳、硫的影响,且一次灰吹时铋扣能快速脱皮、二次灰吹可得到光滑圆整的贵金属碲银合粒。合粒经硝酸、盐酸溶解,电感耦合等离子体光谱法(ICP-AES)测定,铂、钯、金的回收率均大于97%,方法检出限为Pt 0.020 μg/g、Pd 0.020 μg/g、Au 0.021 μg/g。对标准物质测定结果的相对误差(RE)为-4.31%~3.77%,相对标准偏差(RSD)均小于6.92%。     

顺式-二氯[(1R,2R)-(-)-环己二胺]合铂(Ⅱ)的合成与结构表征

顺式-二氯[(1R,2R)-(-)-环己二胺]合铂是一种铂类抗癌药物及一种合成药效基团为(1R,2R)-(-)-环己二胺的铂类抗癌药物的中间体。通过两种常规方法合成了顺式-二氯[(1R,2R)-(-)-环己二胺]合铂,产率均高达90%以上,并采用元素分析、核磁共振谱、红外光谱及X-射线单晶衍射分析对其进行了结构表征。结果表明:此化合物的单晶结构含有1分子结晶水,为单斜晶系,C2空间群,晶胞参数为:a=12.753(3) nm,b=6.8749(16) nm,c=12.325(3) nm,α=90°,β=97.577(3)°,γ= 90°,V = 1071.1(4) nm³,Z=4,Pt-N键长分别为2.047和2.027 nm,Pt-Cl键长分别为2.326和2.330 nm,且Pt²⁺、N和Cl不在同一平面上,可能与结晶水、两个交错排列的分子间N-H...Cl氢键的存在有关。     

一种新型三氮唑铱(Ⅲ)配合物的合成和表征

以5-(4-氟苯基)-1,3-二甲基-1H-1,2,4-三唑(fdpt)为环金属配体、乙酰丙酮(Hacac)为辅助配体合成出一种新型铱(Ⅲ)配合物Ir(fdpt)2(acac)。采用元素分析、红外光谱、核磁共振谱分析和单晶X衍射对其组成和化学结构进行了表征。结果表明,该配合物化学组成为C25H25F2IrN6O2,属于单斜晶系,P21/c空间群。晶胞参数为a=1.58917(14) nm,b=1.64798(15) nm,c=1.06146(9) nm,β=94.741(3)°,V=2.7704(4) nm³,Z=4。     

碳酸二羟基·四氨合铂(Ⅳ)二水合物的合成、表征及性质

合成了一种用作前驱体的,具有八面体结构新型水溶性的金属复合离子型化合物碳酸二羟基.四氨合铂(IV)二水合物([Pt(NH3)4(OH)2]CO3.2H2O),用元素分析和X射线单晶衍射仪(XRD)对其结构进行了表征,用热重-差热(TG-TDA)测试其热分解特性,并对比评价制备DOC催化剂的性能。结果表明,化合物为单斜晶系、P21/c空间群,晶胞参数为:a=0.88191(14) nm,b=1.17817(18) nm,c=1.01533(16) nm,V=0.9978(3) nm³,Z=4,R1=0.0403,wR2=0.1235,R1=0.0466,wR2=0.1353。其晶体结构为以Pt(IV)为中心与4个NH3和2个羟基配位形成八面体的二价阳离子;TG-DTA测试显示化合物分解峰出现在223.8℃;制备得到的DOC催化剂催化活性和起燃温度优于传统前驱体化合物。     

Influence of metal ions on the formation of artificial zinc rusts

The artificial rust particles were prepared from ZnCl₂ solutions dissolving Al(III), Fe(III), Fe(II), Ni(II), Co(II) and Mg(II) at different atomic ratios from 0 to 0.3 in metal/Zn. With increasing metal/Zn the crystal phases of the products turned following as ZnO → a mixture of ZnO and Zn₅(OH)₈Cl₂ · H₂O (ZHC) → ZHC. Al(III) most facilitated the formation of ZHC but Mg(II) and Fe(III) produced no ZHC. The morphology of the formed particles varied following as agglomerate → fine → rod → sheet → irregular with the increase of metal/Zn. The sheet and irregularly shaped particles were identified as ZHC and the other particles as ZnO.     

Effect of dislocation density on the low temperature aging behavior of an ultra low carbon bake hardening steel

Strain aging was studied in an ultra low carbon (ULC) steel with a total carbon content of 20 ppm (wt.%) in order to identify the process stages and mechanism of bake hardening in this type of steel. The effects of dislocation density, varied by means of uniaxial tensile prestraining (1–10%) on the aging kinetics were investigated within an aging temperature range of 50–170°C. The aging was evaluated by means of strength measurements and the determination of interstitial carbon content after aging using a piezoelectric composite oscillator operating at 40 kHz. The interaction between interstitial carbon and dislocations was examined through amplitude dependent internal friction measurements. The influence of dislocation density on the aging behavior have been discussed with reference to the kinetics and mechanism of the aging process.     

A corrosion study of the main constituent phases of AZ91 magnesium alloys

The different constituents of an AZ91 alloy (α,β, and MnAl phases) were synthesized and their corrosion resistance was studied by electrochemistry in ASTM D1384 water, pH 8.3. The pure phases were characterised through the corrosion potential, the polarisation resistance, and polarisation curves, then systematically coupled to assess the galvanic corrosion occurring in the AZ91 alloy. The aluminium content of the oxide film was obtained by X-ray photoelectron spectroscopy measurements. The corrosion rate of the α solid solution alloys depends closely on their Al content. Aluminium enhances the corrosion resistance of the α-phase through the formation of an Al enriched superficial layer. The β-phase is 150 mV nobler than the α-phase, but their corrosion rates are similar. The galvanic currents are low (below 20 μA cm⁻²) whatever the implemented couples and close to the corrosion current previously measured for the AZ91 alloys.     

Mechanism of cathodic delamination control of zinc-aluminum phosphate pigment in waterborne coatings

The propagation of the cathodic delamination and blistering was studied for different waterborne paint systems, with or without the zinc aluminum phosphate (ZAP) pigment. The mechanism by which ZAP reacts at the metal-coating interface to improve coating performance against cathodic delamination and blister formation was investigated by means of scanning acoustic microscopy (SAM), pull-off test and surface analysis. The presence of the pigment clearly enhanced the adhesion and delamination resistance of the coating upon immersion. It has been evidenced how the pH buffer properties of the ZAP pigment play an important role in reducing the advancement of the delamination front. A compact film constituted of zinc and sodium phosphates was found, on the substrate surface, solely within the delaminated area. The precipitation of this phosphate layer on the cathodic sites is thought to polarize the cathodic reaction, contributing to slowing down the delamination reaction.     

Corrosion behaviour of powder metallurgical and cast Al-Zn-Mg base alloys

The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion.     

Influence of a dual-species biofilm on the corrosion of mild steel

The effect of a dual-species biofilm on the corrosion of carbon steel was examined using two bacterial species: the iron-reducer, Shewanella oneidensis (MR-1), and the sulfate-reducer, Desulfovibrio desulfuricans (G20). These experiments exploit the fact that the products of their metabolism (ferrous iron or sulfide) affect the corrosion rate of carbon steel in opposite ways. Electrochemical impedance spectroscopy (EIS) shows that over a short time period, co-cultures of MR-1 and G20 protect steel from corrosion. The fact that an iron-reducing bacterium can inhibit corrosion when a corrosion-enhancing bacterium is present warrants future study with respect to its potential applicability to the design of biological corrosion-control measures.     

Electrochemical behaviour of amorphous and nanoquasicrystalline Zr-Pd and Zr-Pt alloys in different environments

The corrosion behaviour of melt spun amorphous and nanoquasicrystalline Zr₇₀Pd₃₀ and Zr₈₀Pt₂₀ alloy ribbons has been investigated using potentiodynamic polarization study in NaCl, H₂SO₄ and NaOH solutions at different concentrations. The amorphous and nanoquasicrystalline alloys show better corrosion resistance than Zr in all the solutions studied. Both the alloys are susceptible to chloride attack and pitting has been observed. Complete passivation has been observed in H₂SO₄, while gradual break down of passivating layer occurs in NaOH. In general, nanoquasicrystalline state in both the alloys shows better corrosion resistance than amorphous state in all the solutions studied.     

Effect of solution heat treatment on galvanic coupling between intermetallics and matrix in AA7075-T6

Susceptibility to localised corrosion is strongly affected by heat treatments performed on Al-Zn-Cu-Mg alloys. In order to study how galvanic coupling between intermetallics and matrix is affected by solution heat treatment, AA7075-T6 and solution heat treated AA7075 have been characterised by means of scanning electron microscopy and scanning Kelvin probe force microscopy. Solution heat treatment strongly increased the Volta potential difference between the intermetallics and the surrounding matrix showing a strong increase in galvanic coupling. This is explained by Zn and Mg enrichment of the matrix caused by dissolution of strengthening particles during solution heat treatment.     

Effect of moisture (in solid polymer electrolyte) on the photosensitivity of conducting polypyrrole sensitized by prussian blue in solid-state photocells

The effect of small concentration of dispersed prussian blue (PB) [in solid polymer electrolyte viz polyvinyl alcohol (PVA) with phosphoric acid] on the photocurrents were studied (in wet state and in dry state of solid polymer electrolyte) in solid state photocells fabricated using conducting polypyrrole (PPy). These exhibit good photoresponse to visible light: photocurrents being 20 to 25 times greater than the dark currents depending upon the concentration of the sensitizer. The current–voltage (I–V) characteristics in such cells reveals that the charge transport is mainly governed by the space charge effects and the sensitization effects are due to the lowering of the potential barrier formed at the polypyrrole (PPy)/polyvinyl alcohol (PVA) interface under photoexcitation. Also, sensitization effects were studied in the wet state and in dry state of solid polymer electrolyte (PVA). It has been observed that the moisture content in the solid polymer electrolyte reduces the photosensitivity factor (S=I_l/I_d, where I_l is the light current and I_d is the dark current), since it increases the ionic conductivity in the solid polymer electrolyte thereby increasing the dark current values which results in overall decrease in the photosensitivity factor (S). The importance of the other factors such as dye concentration, dye aggregation etc. have been explained on the basis of the experimental observations. The sensitization effects are explained on the basis of the energy band diagram of the materials forming the photocells.     

Effect of anodic oxidation parameters on the titanium oxides formation

The aim of this paper is to evaluate the effects of titanium anodic oxidation in a sulphuric acid electrolyte on the crystallinity of the oxide layer and to adjust the process parameters, in order to maximize the TiO₂ crystalline phase, specially for what concerns the anatase form. In particular, the relationship between anatase formation and anodization parameters, such as current density and applied potential, will be evidenced. From XRD analysis two opposite trends emerged: oxide conversion to anatase is promoted either by an increase in current density or by a decrease in sulphuric acid concentration.