Silver Iron Research Articles

Coprecipitation and X-ray fluorescence determination of iron in copper, zinc, silver, and cadmium metals

Coprecipitation and X-ray fluorescence determination of iron in copper, zinc, silver, and cadmium metals

On the diffusion of iron in silver

In the temperature region 780 to 940 ° C the diffusion of 59 Fe in silver single crystals is investigated. The diffusion coefficient, D=1.90 exp (−49.36/RT) cm 2 /s, agrees with the earlier work of Mullen. The calculations of the correlation factor fi for the Ag[BOND]Fe system using Mullen's results and from the model of LeClaire and the T m -model, further support the vacancy mechanism to be operative in this system. Die Diffusion von 59Fe in Silber-Einkristallen wird im Temperaturbereich von 780 bis 940° C untersucht. Der Diffusionskoeffizient, D=1,90 exp (−49,36/RT) cm 2 /s, stimmt mit dem in der fruheren Arbeit von Mullen uberein. Berechnungen des Korrelationsfaktors f i fur das Ag[BOND]Fe-System mit den Mullenschen Ergebnissen sowie den Modellen von LeClaire und dem T m -Modell bestatigen den Leerstellenmechanismus als in diesem System wirkenden Mechanismus.

Application of the graphite furnace to the determination of trace iron in gold and silver

Atomic-absorption analysis using a graphite furnace is a powerful technique for the determination of nanogram amounts of iron. It can be applied to the determination of traces of iron in gold and silver. These metals may be removed from solution by reduction to metallic gold and precipitation as silver chloride respectively. Iron is not co-precipitated. The iron content can be determined in 50–100 mg of the noble metals with an error of about 7% (or 0·1 ppm).

Development of a theoretical equation for steady-state dislocation creep and comparison with data

Abstract For nineteen materials, including silver, tantalum and gamma iron, Ashby found that an empirical equation e e , = A( D v μb kT )( σ μ ) n gives a reasonable fit to steady-state creep data where A and n are materials constants. It is now shown that if the materials obey the Bailey-Orowan equation, Taylor's work-hardening model and Friedel's network-climb recovery-equation then an identical creep equation is predicted with A = 8π3c∝, and n = 3. Here c∝ = jog-concentration. In the cases of nickel, cadmium, beta thallium and stoichiometric UO2 the predicted and actual creep strengths differ by less than a factor two.

Influence des dislocations sur la cinetique de diffusion du fer, du cobalt et du ruthenium dans le cuivre et l'argent monocristallins

The heterodiffusion of transition metals having very lo′ solubility in copper and silver ′as investigated. Diffusion coefficients ′ere calculated at any temperature from the permeation curves of the C = C 0 erfc X/√ 4Dt type ′hich do not present any anomaly. On silver-iron and copper-ruthenium Arrhenius diagrams, Log D = ƒ( 1 T ) , large positive deviations from Arrhenius la′ ′ere found at 800°C and 900°C for the first and second system respectively. The amplitude of this effect ′as less large for the silver-cobalt system, though iron and cobalt solubility in silver are the same. From volume diffusion parameters obtained for every studied system in high temperature range, the diffusion mechanism for these lo′ solubility solutes is thought to be a classical vacancy diffusion mechanism. The deviations from Arrhenius la′ ′ere explained in terms of an enhanced diffusion due to Frank net′ork dislocations, since it ′as sho′n that the ruthenium diffusion coefficient in copper depends strongly on dislocation rate at 800°C. This volume diffusion kinetics dependence on dislocations at such high temperatures is explained in terms of a large e′uilibrium segregation of solutes along linear defects. Si′e factors account for the behaviour difference bet′een iron and cobalt.

Chemistry of noble metal oxides. II. Crystal structures of platinum cobalt dioxide, palladium cobalt dioxide, coppper iron dioxide, and silver iron dioxide

Chemistry of noble metal oxides. II. Crystal structures of platinum cobalt dioxide, palladium cobalt dioxide, coppper iron dioxide, and silver iron dioxide

Determination of Chromium, Cobalt, Iron, Manganese, and Nickel in Silver by Atomic Absorption Spectrophotometry

Abstract The determination of chromium, cobalt, iron, manganese and nickel by atomic absorption spectrophotometry in silver and silver alloys has been investigated. Samples containing from 2 μg to more than 500 μg in a two-gram sample of silver can be determined by using the same procedure. A series of twenty samples for each element at different concentrations gave an average standard deviation from linear regression analysis of 2.1% for iron, 1.97% for chromium, 2.9% for nickel, 1.6% for manganese and 2.8% for cobalt. The time required for analysis of these five elements in a two-gram sample, including sample dissolution and standard preparation, is approximately three and a half hours.

Spectrographic Determination of Traces of Iron in Copper and Silver by Carrier Distillation

A quantitative spectrographic method has been developed for the determination of traces of iron in high-purity copper and silver. The use of copper chloride as a spectrographic carrier improves the sensitivity and enables the method to be used over a very wide range of concentrations. Samples containing from 0.004 to more than 150 μg of iron (0.07–2500 ppm) can be determined by the identical procedure. A series of 15 replicate copper samples containing 6.4 ppm iron yielded a coefficient of variation of 5.2%. The intensity of the iron spectrum is apparently independent of the copper or silver matrix, which greatly simplifies the preparation of calibration curves. Methods for the preparation of iron-free copper chloride and for purifying graphite electrodes are also outlined.

Diffusion of iron, cobalt and nickel in silver

Diffusion coefficients of iron, cobalt and nickel in silver have been determined over the temperature range 600–850°C using radioactive tracers and the residual-activity technique. The results are as follows (in units of cm 2/sec): D Fe Ag = 9.4 × 10 −7 exp (−29,600/RT) D Co Ag = 3.0 × 10 −7 exp (−29,700/RT) D Ni Ag = 8.5 × 10 −7 exp (−28,700/RT) The frequency factors and activation energies are quite small relative to those for self-diffusion in silver. It appears that the extremely low solid solubilities of iron, cobalt and nickel in silver reduce the flux through the lattice to the point where diffusion along dislocation short-circuiting paths becomes the controlling mechanism. This is in line with the diffusion results previously obtained for these tracer elements in aluminum.

Determination of copper, iron and lead in metallic silver.

Determination of copper, iron and lead in metallic silver.

Frequency factors and isotope effects in solid state rate processes

The movement of defects in solids on the basis of classical absolute rate theory is reexamined with special attention to many-body aspects. The effective frequency in the Arrhenius expression governing these processes is shown to be, in harmonic approximation, the ratio of the product of the N normal frequencies of the entire crystal at the starting point of a transition to the product of the N−1 normal frequencies of the crystal when it is constrained in a saddle point configuration. The influence of the masses of the various atoms on the effective frequency is investigated. It is shown that an effective mass which depends on the direction of the path through the saddle point in configuration space determines this frequency. In the case of chemical diffusion by the vacancy mechanism the effective mass is approximately the same as the mass of the solute atom, and must always lie between the mass of the solute and the mass of the solvent. It is finally shown that the classical rate theory, even with many-body considerations, is unable to explain the recent observations of L azarus and O kkerse on the isotope effect in the diffusion of iron in silver.

Activity Coefficient of Copper in Liquid Iron, Fe-C, And Fe-C-Si Alloys at 1600°C

The distribution of copper between liquid silver and liquid iron, Fe-C, and Fe-C-Si alloys was studied at 1600°C. From the data and the activity of copper in silver obtained from the phase diagrams, the activity coefficients of copper in iron up to 3 atomic pct are log γ Cu = 0.90 − 2.4 NCu and γ°Cu = 8.0. The effect of carbon up to saturation is expressed as log γ(c)Cu = 1.8 Nc. The effect of silicon up to 11 atomic pct is insignificant.