SILICA REFRACTORIES Spectrographic Analysis Using the Direct Current Arc and High Voltage Spark RALPH H. STEINBERG AND HENRY J. BELIC South Works Chemical Laboratory, Carnegie-Illinois Steel Corporation, Chicago, I l l . A method is described for the quantitative spectrographic analysis of silica brick for alumina, titania, potassium oxide, and sodium oxide. The accuracy is comparable with the best chemical methods.
S
ILICA brick is one of the most widely used high temperature
refractory materials. The quality of the brick is adversely Ftffected by the presence of undue amounts of alumina, titania, potassium oxide, and sodium oxide, an accurate chemical determination of these compounds is exceedingly difficult and requires many hours. The spread or range of the results reported by the National Bureau of Standards and the cooperating laboratories on the Bureau of Standards silica brick 102 sample is shown in Table I.
Table I.
Silica Brick 202
Assigned Value,
Range,
%
Constituent AlzOa Tion
%
1.84-2.04 0.15-0.17 0.26-0.31 0.04-0.09
Kz0
Nan0
pin action. The pellet in its holder is used as the lower (+) electrofie. A graphite rod 0.6 em. (0.25 inch) in diameter with a conical tip of 120"included angle is used as the counterelectrode (-). The spark technique described by Steinberg and Relic ( 1 ) is used for the determination of alumina and titania. The powdered silica brick (ground to pass an 80-mesh sieve) is packed into a crater drilled in the end of a graphite rod 0.6 cm. (0.25 inch) in diameter and cemented with 2 drops of a 2% solution of Ethocel (an ethylcellulose ether) dissolved in butyl acetate. The butyl acetate is evaporated in a stream of air. The dried, loaded graphite rod is then used as the lower electrode. The counterelectrode is a graphite rod 0.6 em. in diameter with a conical tip of 120' included angle. Both the powdered graphite used in briquetting and the graphite rods are of special high purity grade. Exposure conditions are shown in Table 11.
1.96
0.16 0.29 0.06
The spectrographic determination of these constituents by the following method requires from 1to 1.25 hours for a single sample. The direct current arc is used as the excitation source for the alkalies and a high voltage spark is used as the excitation source for the alumina and titania.
Table 111. Analytical Curve Data Oxide TiOa
Ala01
KpO KnO
NnaO
NaaO
Element Line 3088.03 3082.16 4044.14 4047.20 3302.32 3302.32
Si Si Ba Ba Ba Ba
Internal Standard Line
Indexo
Range,
%
Excitation
2987.65 2987.65 3611.00 3611.00 2771.36 3315.80
0.18 1.66 0.23 0.30 0.13 0.07
0.07-0.20 0.95-2.10 0,08-0.33 0.10-0.35 0.02-0.30 0.02-0.30
Spark Spark Arc Arc Arc Arc
%
Defined as concentration a t which intensity ratio of analytical line pair (unknown and internal standard) is unity.
EQUIPMENT AND PROCEDURE
The direct current arc is a commercial unit with full wave rectification. The spark unit, consists of a high voltage commercial spark unit of 2 kv.-amp. with an added inductance of 0.045 millihenry and a capacitance of 0.021 microfarad. This unit has a Fuessner synchronous rotating auxiliary gap. These electrical conditions provide a very short period condensed spark.
Table 11. Subject Power source Poiver Preburn Exposure Rotating sector Spectrographic slit width Analytical gap
DEVELOPMENT AND PHOTOMETRY
The film is developed for 2 minutes in Eastman D-19 developer, placed in a 2.57, acetic acid stop bath for 10 seconds. and fixed in Kodak rapid liquid fixer for 45 seconds. After washing for 1 minute, the film is dried by infrared radiation in a stream of Farm air. The film is stretched taut in a film holder and the whole is placed in a commercial microphotometer in order to measure the density of the spwtral lines.
Exposure Conditions For blkaliee D.C. arc 6 amp. None 18 sec. 50% 15 microns 1 mm.
For -41201 and Ti09
WORKING CURVES
Spark 2 kv.-amp. None 11 Bec. None 30 microns 3 mm.
Two film calibration curves are used, one for tbe 3600 to 4300 A, region and the other for the 2500 to 3600 A. region of the spectrum. The analytical curves are prepared by plotting the logarithm of the relative intensity ratios against the logarithm of the concentrations of the various oxides. Thus the percentage of an oxide constituent is taken directly from the analytical curve, using the proper film calibration curve. The analytical curves were prepared by using Sational Bureau of Standards silica brick 102 and several samples of silica brick which were analyzed
The spectrograph is a 1.5-meter instrument with a 24,000 lines per inch grating, providing a uniform dispersion of 7 A. per mm. The camera holds a 100-foot roll of film. Spectrum analysis No. 1 film is used. In analyzing for the alkalies 1.000 gram of silica brick (ground to pass an $0-mesh sieve), 0.600 gram of pure graphite powder, and 0.100 gram of pure barium carbonate are weighed and ground together in an agate mortar. The mixture is then compressed into briquets, each weighing approximately 0.5 to 0.6 gram. The briquet is shaped like a cupcake, being 0.6 em. (0.25 Inch) in diameter at the bottom with sides slightly tapered outward to the dome-shaped top. The compressing operation is carried out in a hydraulic press under a pressure of 250,000 pounds er square inch. The finished pellet is placed in the end of a tubuk r steel holder whose sides are slit to provide a little spring grip
Table IV.
Replicate Determinations on Same Sample
TiOz 700 11 0 09 0.10 0.11 0.10 0.10 0.11
A ~ ~ o ;%, i.00 i.oi 1.06 1.00 1.06 1.06 1.04, 1.04, 1.07 NazO', % 0.0'45, 0.045, 0.05, 0.055,'0.05~ KaO", % 0.29, 0.29, 0.29, 0.28, 0.28, 0.25, 0.305, 0.27
Only 2 decimals are normally reported: t h e third decimal is shown for demonstration of precision.
73 1
V O L U M E 21, NO. 6, J U N E 1 9 4 9 chemically in the South Korks Chemical Laboratory. cal curve data are shown in Table 111.
Analyti-
PRECISION
The general reproducibility of results on a single sample, which is a t present being used as a routine reference, is shown in Table IV. The results shown are for single determinations Ti-ith no corrections for curve shifting, which fortunately appears to be of a very minor character. The figures, taken from routine detrr-
minations, are typical of the checks to be expected and appear t o be of the same order of accuracy as those originally reported by the National Bureau of Standards and the cooperating laboratories on their silica brick 102 sample. Routine samples are generally run either in duplicate or triplicate and the average result is reported. LITERATURE CITED
(1) S t e i n b e r g , R. H., a n d Belic, H. J., ANAL.CHEM.,20,72 (19481 RECEIVED September 29, 1948.
X-RAY DIFFRACTION PATTERNS For the Identification of Surface-Active Agents THO3TiS F. BOYD, J. MALCOLM MAC QUEEN^, AND IRVISG STACY2 Philadelphia ,Varal Shipyard, Philadelphia 12, P a .
S
URFACE-active agents have acquired a Fide field of usefulness as detergents, emulsifying agents, dispersants, and wetting agents. Considerable investigation and development of commercial synthetic detergents are conducted a t this laboratory, and a rapid method for the identification of active ingredients was desirable. A4rapid method was also necessary as a basis for specifications requiring certain compositions in lieu of performance tests. The authors have prepared a file of x-ray data for 19 common surface-active agents for use in the synthetic detergent work of the laboratory ( 2 ) . EXPERIMENTAL PROCEDURE
The surface-active agents were separated from commercial products by tn.0 extractions n i t h 95% ethyl alcohol ( 1 ) . X-ray diffraction transmission patterns on film were made using a General Electric X R D unit and a flat cassette. The distance from the film to the sample holder v a s set a t 100 mm. Two-hour exposures were made with unfiltered copper radiation a t 40 kv. and 15 milliamperes. Photographs were taken using both the 0.25-mm. (0.010-inch) and 0.025-inch collimating systems. The distance from the film to the sample !vas calibrated n i t h sodium chloride. EXPERIMENTAL DATA
fi.vn n I s c u s s i o N
Interplanar spacings calculated from photographs are sh0n.n in Table I. The scale of intensities is an arbitrary one on which 10 represents the most dense line and 1 the faintest line. As a supplementary study. measurements of interplanar spacings and intensities Kere also made, using a S o r t h American Philips x-ray spectrometer, Type 12021. It was found that more lines and halos were recorded photographically than on the spectrometer chart and that the spectrometric measurements of 28 were in general less reproducible. However, more reproducible values of 28 were obtained for very high interplanar spacings using the spectrometer. .-it the high interplanar spacings, the width of the incident beam was limited by an extra slit in front of the regular slit and the 28 values n-ere obtained by setting the goniometer manually for the greatest numher of counts. .ACKNOWLEDGMENTS
Acknowledgment is made to Louis Goldberg and Myrtle Oberholtzer who assisted in obtaining data. The authors thank Henry Sloviter, Rubin Bernstein, and Joseph Simkin for their advice during this study. The authors wish to acknowledge the 1 1
Present address, 349 McClain .4ve., Coshocton, Ohio. Present address, 1673 East 13th St., Brooklyn 29, N. Y
Table I. Diffraction Data for Nineteen Crystalline SurfaceActive Agents Sgacing,
A.
1. Sorbitan hlonostearate 61.6 10 15.7 1 4.18 6 Sodium Salt of Sulfonated Ethyl Methyl Oleyl A m d e 51.5 10 25.0 4 16.8 3 5.03 3 4.44 2 3.96 4 3.78 2
2.
3.
4.
Sodium Oleyl Sulfate 50.0 10 36.7 5 24.5 4 16.6 2 4.34 4 4.10 3 Stearyl Amide of Sulfonated Sodium Succinate 48.6 10 22.6 3 14.9 2 4.20 2 Halo 40.7 4
5.
Sodium Salt of Sulfonated Ethyl Oleate 48.4 10 24.5 4 15.7 3 4.08 4
6.
Sodium Lauryl Sulfate 42.7 71.7 13.8 4.34 4.06
7.
Spacing, A.
Intensity
1; 4 1 2
Sodium Lauryl Sulfoacetate 41.4 10 20.8 4 13.7 3 5.17 1 4.59 2 4.14 4
Spacing,
8. Sodium n-Octyl Sulfate 29.6 4.32 4.08 9.
A.
Intensity 15.
1; 4
Dodecyl Benzene Sodium Sulfonate 26.5 10 21.6 1 18.5 1 13.4 2 Halo 4.97 3
10. M o n o b u t y l Phenyl Phenol Sodium hlononiilfnnate 26.2 10 13.0 2 10.4 2 7.02 2 Halo 4.85 I 11. Decyl Benzene Sodium Sulfonate 25.7 10 20.5 1 17.2 1 12.6 2 Halo 4.83 3
12. Sodium Di-3,7dimethyl Octyl Sulfosuccinate 26 2 10 14 4 1 Halos 48.1 4 4.98 1 13. Monobutyl Diphenyl Sodium Monosulfonate 25.0 10 15.5 2 13.0 2 10.4 2 Halo 4.85 1 14. Diootyl Ester of Sodium Sulfosuocinrte 21.7 10 6.17 2 4.32 2 3.27 2 Halo 4.14 3
Intensity
Diamyl Sodium Sulfosuccinate 20 0 10 9.60 1 8 85 1 4.34 1 Halo39.5 1 4.91 2
16. Dihexyl Ester of Sodium Sulfosuccinate 19.7 10 18.4 9 4.96 3 4.70 1 Halo 40.7 3
17. Sodium Tetrahydronaphthalene Sulfonate 19.7 10 15.7 3 5 72 4 5.56 ! 4.87 4 . .53 1 4 31 2 4.11 1 3.84 2 3.68 1 3.48 1 18.
Dibutyl Sodium Sulfosuccinate 16.4 10 9.19 4 7.79 2 6.55 1 5.39 1 5.08 4 4.66 1 3.97 4 3.47 4 3.28 2 3.14 1 3.05 1
19. Sodium m-Xitrobenzene Sulfonate 20.3 4 15.5 10 8.25 1 5.84 1 5.07 3 4.18 4 4.01 3 3.38 2 3.27 4
