Manganese, Chromium, and Nickel in 18-8 Alloy Steels -4 Rapid Sequence Titration LOUIS SILVEIZ3I.\V . i h D O W E S (;.\‘[E5 ,5559 Hobart S t ., Pittsburgh, Penria.
1 0.2 gram-sample of steel solution, w-hich has been completely oxidized by the silver-persulfate method, is used for the successive determination of manganese, chromium, and nickel. 4 description of
lcnow-ri methods of analy ais for silicon. columbium, phosphorus. and moly-bdenum is included to correlate this new sequence method Ttith anal?sis of the other elemm LS mentioned.
I
N ALLOY steels containing 10 t o 30 per cent of chromium and 7 t o 20 per cent of nickel, the chromium and nickel
In Table I is compiled a series of aiialyses wliicli are coinpared with those of the manufacturer or contractor supplying the steels. I n Table 11, the values for Bureau of Standards sample No. 121 are given, using Bureau of Standards N o . lOla as standard.
are usually titrated on the same sample, in sequence. Manganese, however, is determined on a separate sample, by arsenite after the zinc oxide separation (Q),because the brown color of the manganic salts obscures the end point when much chromium is present. Another possible combination is made possible by the use of mercurous nitrate (3). After oxidation of manganese and chromium t o permanganic and dichromic acids, respectively, the manganese is determined by the mercurous nitrate, and the chromium by ferrous sulfate &susual. ~h~ nickel, however, cannot be determined by cyanide on this aliquot, because of the interference of mercuric salts. Investigations, with t h e aid of the electron bean1 seetrometer, indicated that permanganic acid could be accurately titrated vith the arsenite-nitrit’e reagent of Sandell, Kolthoff, and Lingane (7) and chromium and nickel could subsequently be determined on t h e same sample. Experimental conditions were then established, such that visual titration of manganese was equal in aec‘1rW’ t o that of the sectrometel when used as indicator.
TABLE I. C
5 Authors Manufacturer
3In
s
(.‘OMP.~R.LTIYE
.Irar.rs~s
S
Si
S i
Cr
Cb
$I %
2
cic
“0
7c
18.8 18.85
P
Solutions
.. ..
0.07
0.07
0 . 9 2 0,120 0 . 9 8 0.1‘36
0.052 0.044
0.53 0.54
9.2 9.37
Buthors Manufacturer
0.06
1.F4 1.74
0.020 0.018
0.010 0.014
0.50
0.52
11.5 11.3
18.2 0.83 18.05 0.81
Buthors Manufacturer
0.07
0.56 0.58 0.30
0.012 0.016
0.013 0.010
0.013 0.015 0,010 0.015
11 22 .. 43 9.4
0.81 0.77
0.018 0.53 0 . 0 1 8 0 . 3 2 0.015 0 . 3 1 0.017 0.47 0.024 0.05 0 . 6 8 0.018 0.07 0 . 5 6 0.019 0.07 0 . 5 6 0.011 O,OO 0.92 0 , 1 3 3 0.069 0 . 9 4 0.138 0.00 0.44 0.131 0.06 0.37 0.154 0.09 0 . 4 1 0.018 0.09 0 . 4 2 0.016 0.013 1 . 2 5 0.01s 0.06 1 . 3 1 0.018 0 . 0 ~ 1 . 3 ~0.014 0.065 1 . 3 7 0.021
0.47 0.47 0.44
18.5 18.4.5
Authors Manufacturer
9.0
..
0.40
18 8 18.6
0.36 0.30
18.3 18.3
.,
0.36 0.44
10.5 9.8 9.5 9.3 9.1 9.3
0,5x
i o ,a
Authors Manufacturer Authors Manufacturer Authors Manufacturer Authors 3lanufacturi.r Authors Manufacturer Authors Manufacturcr Authors Manufacturer Authors Manufacturer
0.06
0.07 0.06 0.07 0.05 0.05 0.05
0.009 0.013 0.010 0.013 0 . 066 0,084
0.014
0.37
0.34
0.43
9.24 9,I
18.; 16 1 19 2 19.25 18. .i 1 8 . %i 19.2
0.52 9 . 4 3 18.3‘1 0.47 18.4 0.010 0 . 4 8 8 . 3 0.008 0.43 S . 5 2 18.5.: 16.2 0,009 0 . 6 1 11.1 0.012 0 . 5 6 10.9 18.19 0.010 0 . 4 . j 9 , ~ 17.; 0.010 0 . 4 : i 0.Ii 17..j 0.014
,.
A ~ ~ ~ prepare ~ ~0.1 N~ arsenite ~ -by dissolvillg N ~ 4.95 grams of arsenious oxide in about 20 cc. of 20 per cent sodium hydroxide solution. Using phenolphthalein as indicator, decolorize with dilute sulfuric acid, add 500 CC. of n-ater and 20 to 25 grams of sodium bicarbonate, and decolorize with acid if necessary. Dissolve 7.0 grams of sodium nitrite in 200 cc. of water. Mix arsenite and nitrite, and dilute t o 2 liters. This is the stock 0.1 N solution. For use, dilute t o 0.02 N , standardize on a steel of about 1 per cent manganese, to which 20 per cent chromium has been added, and check with Bureau of Standards sample No. lOla or 121. FERROTS A 4 ~ 1 ~ f 0 x 1 SULFATE. 1x Dissolve about 46.0 grains (0.115 N ) of ferrous ammonium sulfate in 500 cc. of m t e r containing about 5 CC.of sulfuric acid. Dilute t o 1 liter. CITRICACID SOLCTION. To 380 grams of ammonium sulfate add 270 cc, of concelltrated ammonium hsdroxide, 1430 cc. of water, 5 grams of ammonium chloride, and 240 grams of citric acid. V T P 30~cc. on a 0.2-gram aliquot. ST.4ND.4RD SILVER NITRATE SOLUTION, 2.885 grallls of silver nitrate per liter. Use 5 * 0.1 cc. CYAKIDESOLUTIOX.Dissolve about 7.5 grams of sodium cyanide and 7 grams of sodium hydroxide in 1000 cc. of water. Dilute to analyst’s Se 11’1 convenience. 70 c; P o ~ a s s ~ u IODIDE, hi 200 grams of potassium iodide 0.26 .. per 1000 cc. of Use 2 cc. 0.23 ., ~ ~ I X E.~CIDS. D &,fix900 cc. of concentrated 11s.. .. drochloric acid, 300 cc. of concentrated nitric acid, and 1000 cc. of water. Use about 20 cc. for 2 grams. .. .. .. .. TIME-SAVISG ACID-SILVERSOLCTION. Mix 500 cc. of water, 1000 cc. of sulfuric acid, 5.77 grams , , . of silver nitrate, and 120 cc. of phosphoric acid. .. .. Dilute to 2 liters. Use 5 cc.
.,
., ..
.. .. .. ..
.. .. .,
..
.. ..
,,
.. ,,
..
0.34 0.32
.. .. .. ..
.. .. .. ..
..
,,
..
.. 318
.. ..
Experimental
.. .. 0 ,IC, 0.16
.,
.. ., .. ,
.. 2.60 3.00
Vse Bureau of Standards samples lOla and 121. Dissolve 2-gram samples in aqua regia, then fume Lvith 18 cc. of perchloric acid to eliminate chlorides. ..ifher cooling, diluting with water, and boiling out chlorine gas, filter the solution through paper and LTash \yell. )lake up the filtrate t o a known volume, and transfer 0.2-gram aliquots t o 400-cc. beakers. To the beaker add 5 cc. of silver nitrate solution, j cc. of (1 1) sulfuric acid, 0.3 CC. of glacial phosphoric acid, and 20 cc. of 6 per cent ammonium persulfate. Add water to make the solution up to 100 cc. Heat the solution to complete the oxidation
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~
~
ANALYTIC.4L EDITION
SEPTEhIBER 15, 1940
(519
Procedure TABLE11. ANALYSIS OF STEEL ~ l i n r e a uuf Standards S o l 0 l a used a s e t a n d m d . Xi 8 98) 3111
5; liureau of Standards S o . 121
0.41
.iuthor A, regular method Proposed method A u t h o r B, propmed niethoil
o:i1 0.30
l l n 0.47, Cr 16 33,
Cr %
Si
l i . 83
8.04
iiIcu,ATD NICKEL. Dilute the volumetric flask solution t o the mark. Transfer a 0.2-gram aliquot to a 400-cc. beaker. Add 5 =t0.1 cc. of silver nitrate solution, 5 cc. of (1 1) sulfuric acid solution, 0.3 cc. of glacial phosphoric acid, and 20 cc. of 6 per cent aninioiiiuni persulfate solution. Dilute with water to about 100 cc. Heat to complete the oxidation of manganese and to destroy excess persulfate, without boiling. Remove from the heat, and cool to 5” to 10” C. Titrate slowly with standard arsenite-nitrite solution (1 minute for first 5 cc., and 0.5 minute for each extra 5 cc.), shaking the beaker above a sheet of white paper. Dilute the solution to 200 cc. with cold water, and add 5 cc. 1) sulfuric acid solution. Titrate with standard ferrous of (1 sulfate solution using a potentiometer (mercury, mercurous chloride, potassium nit,rate with platinum electrode) as indicator for the chromium. Add 50 cc. of citrate solution IThich contains enough chloride to precipitate the silver, and then just enough ammonium hydroxide to dissolve the precipitate ( I ) , thus adjusting the acidity. Add 2 cc. of the potassium iodide solution, and titrate with standard cyanide solution to the end point for the nickel. MOLYBDEP~CM (a). Cool a suitable aliquot, treat with 15 cc. of 20 per cent stannous chloride, 5 cc. of 5 per cent ammonium thiocyanate, 10 cc. of (1 1) sulfuric acid, and 1 cc. of hydrochloric acid (1.2 sp. gr.), then extract the molybdenum by ether, butyl acetate, or cyclohexanol, and compare with a standard. PHOSPHORUS.Use the remainder of the solution or a suitable aliquot. Add 5 cc. of nitric acid (sp. gr. 1.4) and about 2 drops of concentrated hydrochloric acid, boil down to 50 cc., add molybdate solution and ammonium hydroxide, and complete by any favored method ( 5 ) .
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Literature Cited (1) Griffin, R. C., “Technical Methods of Analysis”, p. 20, Xew York, McGraw-Hill Book Co., 1921. (2) Hurd, TKD. ENG.CHEM.,Anal. Ed., 6, 477 (1934); 7, 396 (1935). (3)mKolthoff and Furman. “Potentiometric Titrations”,. P. 284, New York, John TViley & Sons, 1926.
Latimer. “Oxidation Potentials”, p. 223, New York, Prentice Hall Co., 1938. Lundell, Hoffman, and Bright, “Chemical Analysis of Iron and Steel”, p. 220, New York, John Wiley & Sons, 1931. Ibid., p. 298. Sandell, Kolthoff, and Lingane, IKD. ESG. CHEM.,Anal. Ed., 7, 256 (1936). Silverman, Ibid., 6, 287 (1934). Ibid., 8, 383 (1936). Smith, “Perchloric Acid”, Columbus, Ohio, G. F. Smith Publishing Co., 1934. Smith and Gets, ISD.ESG.CHEX.,.hal. Ed., 9, 37s (1937).
