Spark Excitation Research Articles

Applicability of Controlled Atmosphere Excitation to Spectrographic Methods of Analysis of Aluminum Alloys from Compacted Chips

For further improvement of reproducibility of intensity ratios of constituent vs. aluminum lines, noted when argon atmospheres were used in the spark excitation of aluminum alloy (Alcoa 24S) chip compacts,1 a study was made of the effects of the following factors: chip size, carbon bonding, shape of pellet, sample pellet to sample pellet and to carbon electrode forms. The results show that unbonded, flat tipped pellets to carbon counter-electrodes produce the most desirable combination. Chip size does not have a significant influence on the results. Analytical working curves for Mn, Mg, and Si covering the percentage ranges found in Alcoa types 14S, 17S, A17S and 24S were obtained for flat pellet versus pellet and versus carbon electrode forms. The slopes of all curves for the latter combinations are essentially the same as those for working curves obtained by the use of the conventional solid aluminum disc vs. carbon counter-electrode in air. Lateral shifts of curves for pellets in argon are in a direction indicating a decrease in energies available to neutral atom transitions. Standard errors of estimate, except for Mn, are nearly twice those for the conventional technique indicating need of additional improvement in the pellet form and size for more reproducible sample material.

A method for determination of dissolved aluminium and alumina in steel

A part chemical and part spectrographic method is described for the determination of aluminium and alumina in steel. After separation of the two compounds by acid solution, the iron is removed from the filtrate containing the aluminium by mercury cathode electrolysis. Since difficulty is experienced in the concentration of the electrolyte to a suitable volume because of the sulphuric acid present, 8-hydroxyquinoline is used to precipitate the aluminium. This precipitate is taken into solution, as also is the reserved alumina precipitate. Known volumes are impregnated into specially prepared graphite electrodes and spectra obtained by spark excitation. Working curves are prepared from synthetic solutions and the method is reproducible to ± 0,001 % Al. A comparison is made between spectrographic and chemical results.

アナリスコープによる鐵鋼中珪素の直視迅速分析法

The visual spectroscopic method was employed for the rapid determination of silicon in pig iron while tapping. The red line pair Fe 6400År35/Si 6347År35 with spark excitation was observed with the partly reformed "Analyscope" (Japanese spectroscope of steele-scope-type).Testing was made with about more than one hundred samples taken from blast furnaces, and the result thereof showed that the rapidity was enough satisfactory but the sensitivity and the accuracy were somewhat inferior to those of chemical analysis. The method was also found to be applicable to steel samples. Further improvement of the apparatus was desired in conclusion.

Etude comparative de différentes conditions d'excitation pour l'analyse spectrale quantitative des laitiers

Different techniques for the quantitative spectrographic analysis of slags have been studied. Three sources of excitation have been employed: (1) the direct current arc; (2) the Feussner spark unit; (3) the “ multisource”. The best operating conditions have been determined for each source. Results obtained with these conditions have been compared with regard to the reproducibility of measurements, the slope of analytical curves, and the influence of the variation of oxide/silica ratio for some elements on the logarithmic intensity ratio of other elements being determined. Results obtained by spectrographic methods have been compared with those obtained by chemical analysis. ' Conclusions that can be derived from all results obtained are communicated. It may be indicated that the best results are obtained by spark excitation using the Feussner spark unit. For several elements results obtained by this technique are proved more reliable than those of routine chemical analysis.

Direct Spectrochemical Analysis of Solutions Using Spark Excitation and Porous Cup Electrode

Direct Spectrochemical Analysis of Solutions Using Spark Excitation and Porous Cup Electrode

Spectrographic analysis of slags using spark technique

A method is described for the quantitative spectrographic analysis of slags. A high voltage condensed spark excitation is used with powdered samples on a flat pure graphite electrode. Calibration curves have been prepared both for the determination of percentage of different elements in slags, using cupric oxide as an internal standard, and for the determination of Oxide/Silica ratio's, using a mixture of sample with pure graphite. The method gives sufficient accuracy for slag control, and results obtained for several elements are proved more reliable than these of routine chemical analysis.

The quantitative spectrographic analysis of Brittania-metal with spark excitation : Gillis, J., J. Eeckhout and M. van Doorselaer Anal. Chim. acta 1, 209–217 (1917)

The quantitative spectrographic analysis of Brittania-metal with spark excitation : Gillis, J., J. Eeckhout and M. van Doorselaer Anal. Chim. acta 1, 209–217 (1917)

Quantitative spectrographic analysis by spark excitation of metallic oxides

A new spectrographic technique is described for analysing a finely ground powder, such as a mixture of metallic oxides, which is placed in a crater in the lower electrode of a spark discharge. The powder is ejected continuously into the vapour column, and a source combining good sensitivity and reproducibility is obtained. This technique has been used successfully for many metallurgical analyses, more especially those which are not of a routine nature. It appears that ejection is brought about by electrostatic repulsion rather than by thermal or convective effects, and that the large amount of material passing into the discharge makes it arclike in character.

Spectrochemical Analysis of High Copper in Cast Iron and Steel

Analysis of copper in steel and cast iron is easily carried out spectrographically with spark excitation in the range .02 to .20 percent using the 3274A copper line and the 3264A iron line, and in the range .20 to .80 percent with the 3286A iron line. These methods, described in detail herein, are not reliable for higher percentages of copper in cast iron and steel due to reversing of the 3274A copper line and segregation of copper in the iron with increasing copper concentrations. A unique method is described in detail which enables the spectrographer to analyze copper in cast iron and steel up to 2.50 percent (higher if standards are available). The method advocates the use of the a.c. arc at 5 kv and 112 amperes for two reasons. The analysis lines chosen for calibration using the general internal standard method are the 2824A copper line and the 2819A iron line. Since copper percentages do not normally exceed .80 percent in the steel to be spectrographically analyzed by our laboratory, the technique described herein was developed primarily for cast iron in which copper percentages of three percent are not unusual.

SPECTROGRAPHIC ANALYSIS OF PLANTS AND SOILS

SummarySpectrographic methods which are applicable to the analysis of plants and soils include those employing flame, arc and spark excitation. Some seventy elements can be determined spectrographically, the most important exceptions being gaseous and non‐metallic elements.The most widely used flame emission method is that devised by Lundegårdh, in which the solution under examination is sprayed into an air‐acetylene flame. This method is particularly suited to the determination of the alkali and alkaline earth metals in soil and plant extracts. The Ramage method, in which the material is introduced on a paper spill, has also been used to some extent.Arc methods are widely employed for the determination of both trace and major constituents, generally with solid material in carbon or graphite electrodes of a shape chosen to suit the object of the investigation. The most sensitive source for most elements is probably the cathode‐layer arc, although the high‐voltage a.c. arc is useful for certain elements in solution. Interrupted arc and spark sources have been less widely used but have advantages for certain purposes, such as the determination of boron.Some direct photometric methods, omitting the use of a photographic plate, are described.Spectrographic methods are applicable to qualitative, semi‐quantitative or quantitative determinations. Semi‐quantitative methods generally employ a visual or subjective assessment of the content of an element, and are useful in giving a general indication of the levels of most of the trace constituents present in any sample, with an accuracy of some 30%. When objective photometric measurements are used, figures reproducible to ± 3–10% may be expected, depending on the method employed and the element being determined.Applications of spectrographic methods to analyses of soils and plants have been along both lines, either the semi‐quantitative survey of as many elements as possible, or the quantitative determination of specific elements. Attention is drawn to the relationship of the soil content to the geological origin of its parent material and to soil effects which may influence plant uptake.

Photo-Ionization of a Gas by a Discharge in the Same Gas

Method. Measurements were made in a tube containing two thermionic units electrically shielded from each other. The first served to give a discharge, the second detected ions produced by the radiation from the first by means of their effect on the space charge.Results. Relatively little photo-ionization is produced by arc radiation, while spark excitation and soft x-radiation give a strong effect. Curves of photo-effect versus discharge voltage show critical potentials which have been interpreted as follows: Ionization of ${n}_{2}$ rare gas shell---Cs, 13.0; K, 19.0: Spark excitation---Cs, 18.5; K, 21.6; A, 32.2; Ne, 48.0: Double ionization---Cs, 21.5; K, 31.8; A, 34.8; Ne, 54.9: Ionization of ${n}_{1}$ rare gas shell---Cs, 39.0; K, 48.0; A, 39.6. The neon II spectrum is excited at 55 volts.It was shown that photo-electric emission from the electrodes was at least ten times as great as the photo-electric emission from the gas, while the current change produced by the space charge effect was more than 2400 times the ion current in argon and caesium, the upper limit being quite indefinite.

Fluorescence of Cadmium Vapor

Fluorescence of cadmium vapor.---Cadmium vapor, in an evacuated and carefully baked quartz tube, when illuminated by cadmium, iron and nickel sparks, was found to emit the lines 3262A ($1S\ensuremath{-}2{p}_{2}$), 4678A ($2{p}_{3}\ensuremath{-}1s$), 4800A ($2{p}_{2}\ensuremath{-}1s$) and 5086A ($2{p}_{1}\ensuremath{-}1s$) much more strongly from freshly formed vapor than from older vapor. The line 2289A ($1S\ensuremath{-}2P$) also appeared slightly stronger in the freshly formed vapor when illuminated by the cadmium spark; it was not excited by iron and nickel sparks. Experiments are described which indicate that it was the freshness of the vapor, not primarily the temperature or pressure, which determined the intensity of the radiation. The effective exciting light was absorbed by glass, hence shorter than 3300A. A Cu spark did not excite the lines, at least in the visible.Fluorescence of thallium and indium vapors.---Impurities in the cadmium vapor gave strong fluorescent Th and In lines, ($2{p}_{2}\ensuremath{-}2s$) and ($2{p}_{1}\ensuremath{-}2s$), although spark spectra using the cadmium metal as electrodes did not reveal their presence. These lines were radiated only by the freshly formed vapor and appear to be the result of directly absorbed radiant energy rather than of collisions of the second kind. They were weaker with Cd spark excitation than when light from a Ni or Fe spark was used. Light from a Cu spark excited only the Th lines.