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Extension of the isotopic method for the determination of oxygen in titanium
VOL.
16 (1957)
STARILIT~
THERMIQUE
DES
BTALONS
ANALYTIQUES.
IV
325
%USAlMMENFA,SSUNG Ln diescr vim-ten Arbcit hber Verglcichssubstanzen wurdcn die Thcrrnolysekurvcn und Ultrarotspektren im festcn Zustand von I 2 Vcrbindungcn bestimmt,wclchc in vcrschicdcncm Masse ZIII HcrstellunF: van anal>rtisch-chemischcn TitcrWsungcn dienen k&men. HIBLIOGHAPHIE Ii. J>UVAL 15-r J. LWONTJ~, Conrp/. rend., 2x3 (1941) (~9% C. DUVAL ET J. LECOMTE. Comfy/. rend., 272 (1941) 389 ct 696; Bull. SOC.chinr. Frcorre, S (1942) 548. C. WUVAL ET S. PELTIER. Compf. reprd., 220 (19411) 1727. Mllc DUVEAU, Diplhe d’&fths Supdriorres, Paris, 1042. Mllc C. ROCCHICCIOM, Compl. vend., 242 (rgg0) 2922. Elscvicr l~‘ublishing Company. :\mstc!rclarn, C. DUVAL, Incwgakc Thernropravimefric Arrdysis, 1953. 1~. 172. T. DUPUXS. Cotnfil. rerrd., 242 (1956) 2224.
EXTENSION 01; DETERMINATION
THE
ISOTOPIC OF OXYGEN
METHOD FOR IN TITANIUM*
THE
I,>
I?esearclr lnsliirr~e of ‘I’enrfile Unirtersily,
Philadelphia,
Pa.
(U.S.
.*I.)
The use of the isotopic method for the determination of oxygen in mctals1*!*3 has now been applied to titanium in the range of o.od-0.2 wt. Oh,O.I’his method is based on reacting a weighed sample of titanium metal mixed with a known amount of and liberating “master alloy” in the ~tzoilcn state with graphite ‘“O-containing part of the oxygen as carbon monoxide. The 1sO/160ratio in the carbon monoxide is determined by a mass spectrometer. Method
The percent
oxygen,
x, is calculated .2: =
where a
100
of calcrrlatio~r
from the simple mixture
bt(na-n)
-_--._
at&
-
(clr--rtv) . .__...- .___-_
a
rule, namely:
1
weight of sample; weight of titanium “master alloy” containing L weight fraction oxygen, with ??Iatom o/oof oxygen-x8 in excess of the normal** isotopic concentration (W 0.21 at. o/o leO); C _Z weight of crucible containing 21 weight fraction oxygen; (I weight of graphite containing v weight fraction oxygen; n = atom ()& of oxygen-r8 in excess of normal concentration after equilibrium. Because isotopes are preferably mixed and measured on an atom per atom basis, .-.-_. . _. .. b
=
l Presented before the Xnalytical Section of the American Chemical Society in Xew York, N.Y., Sept. 13. 1954. l * ‘The exact normal ,isotopic concentration is determined before each series of analyses.
Refersrks’p.
aa
A.
226
D. KIRSHEkBAUIM, A. V. GROSSE
VOL. 16 (x957)
61 should be expressed either in gram-atoms or, more simply, in weight units using the same atomic weight of the element as in a. Thus bt is not expressed in actual milligrams of the heavy isotope, but in equivalent milligrams of the normal isotopic mixture (see Ref. 1, p. 760).
The apparatus and proccdurc used wcrc clcscrihcd in detail prcviouslyr*2. Tt was found recently3 that by replacing the graphite crucible wit11 a molybdenum one (maclc from 0.25 mm sheet metal), tl~c oxygen blank correction can Gc rctlucctl from about 3 mg down to o.or mg.
Sn,,lplcs
N rrrllyzclc
The titanium metal samples wcrc supplied and analyzed by E. 1. du Pant and tlrc hllcghcny T.lctllum Steel Company by the vacuum fusion mcthod4.
de Ncmours
& Co.,
The data obtained by the isotopic method are tabulated and compared with those obtainecl by the vacuum fusion method in Table J. It is of interest that the vacuum fusion data are IO-IS%, lower than the isotopic values. ‘This would indicate that in the vacuum fusion analyses not all of the oxygen has been liberated as carbon monoxide and that some of the oxygen is held by the metal. This concurs with the findings of HORTON AND I~I~ADY~ who rccovcrcd only 85-7o”A, of the oxygen by the vacuum fusion method in the case of chromium. Similarly, RODGERS AND HAI~TERO using the same method, found that the recovery of nitrogen was not quantitative in analyzing zirconium metal. In their case the determination of nitrogen, in the form of ammonia, by the Micro-Kjeldahl method gave higher values than the vacuum fusion method.
OlSTlCllhllNATION
(In all cases j)d =
136762
012
OSYGEN
atom o(,reO,l /
u, g weight of suhstancc 6 weight of master alloy f: i- (1, g weight of grspliitc 11, atom, I<, llrO above ncxmal after equilibration
h,
#RI--_)I
.V = wt. OA, 0 in sample, observed * * wt. y<, 0 by vacuum fusion Wffcrcncc, o/O of 0 content, isotopicvacuum fusion
IN
TITANIUM
=
r .8o557 0.17860 2.7273 6.7534 6.9228 0.0483 0.0436 i-9.7
.-. ..-- -- -.-.-----.-.._--.- ._._. . _.._-- . ..-_.-._-~___-._--* Analyzed by supplier.
BY
THE
ISOTOFIC
MRTHOD
r.Sgr7wt.O~,Oandu=u
I .oosqr)
o*r3.)79 “.0)505 4~9772 8.6ggo 0.1378 0.1219
G2I.S
_...._ ..._._ -.
= o.rgowt.“/oO)
2.22325
2.2ISr)S
0.14674 2.328s 3.6417
cr.15474 2.2374
3.7352
10.0345 0.1870 0.165 j-1 1.8 _-_._
994ro 0.2005
0.175 -1_12.7
___---_-----
A possible error leading to a higher oxygen content by the isotopic method might be due to an exchange between oxygen-18 of the carbon monoxide and the oxygen-16 in the quartz. This error possibility, however. was shown in a previous publication2, to amount to less than 0.5% of the actual oxygen content of the sample. I
.
VOL.
16 (1957)
UETERhflNATION
OF OXYGEN
227
IN TITANIUM
The only other way the isotopic method might give erroneously high results is if air leaks into the apparatus. This would immediately reveal itself by the appearance of atmospheric argon peaks in the mass analyses. However, no argon was found in any of our samples. ACKNOWLEDGEMENTS
The authors wish to express their thanlcs to Dr. R. H. ~LlXKKNSlEIN of the Du Pant Company and to Mr. W. A. Psrrw~ of Allcghcny Ludlum Steel Company for supplying us with thr: titanium samples.
Our oxygen of 0.04 results found
method of isotopic elomcntnrv analysis has rcccntly been appliad to the dctcrmination of in metals. It is now cxtcnclccl to the determination of oxygen in titanium in the low range to 0~2 weight pcrccnt osygcn. Tho method has the great advantage that it gives qunntitativc wil/rorr/ a quantitative separation of oxygen in any form. In the !JitttlplcS analyzed it \ViW that the nltcrnativc vacuum-fusion m&hod gives results which arc g-130/” too low.
Notre m&hode isotopiquc tl’analysc &lbmcntaire a &6 appliquCc r&zcmmcnt ill1 dosage dc I’oxyg&nc clans lcs m&aux. Ella cst appliqu& maintcnnnt au dosage clc l’oxyg:c\ncrclans lc titanc. cn poitls d’oxygbnc. Ccttc mdthotlc prdscntc lc grand avantagc pour dcs tcncurs dc 0.04-0.27;, de donncr dcs r&ultnts quantitatifs SUNSsdparation quantitative rlc l’oxygbnc. Nous nvons constat& que, pour les dchantillons analysbs, la mdthodc do fusion tlans Ie vitlc clanne clcs rCsultats 9 Q 13%, trop faiblcs.
Vor kurzem wurdc unsure lsotopen-Methodc dcr Elomcntar-Analywe auf die Bcstimmung von Saucrstoff in Metallen angcwandt. Dcr Anwcnclungsbcrcich dcrsclbcn wurclc nunmchr auf dir: Bestimmung van Saucrstoff in Titnn, in dem nicclcren Bercich von 0.04 bis 0.2 Gcw. o/o Snucrstoff crweitcrt. Dcr grossc Vortoil tlcr Methode ist darin zu crblickcn, dass sic, olrrredie quantitative Ergebnissen Abtrcnnung dcs Saucrstoffes in irgcndcincr Form zu crfordcrn, zu quantitativcn flihrt. Es zcigtc sich, dass tlic Anwcnclung dcr altcrnativcn Vnkuumschmelzmethocle auf die Saucrstofflwstimmung in den untcrsuchtcn Probcn Wcrte licfcrt, wclchc urn g-13?<, zu nicdrig licgcn. REFEREKCES 1 2 3 4
A. D. ~~IRSHENBAUM AND A. D. I<;IRSHENBAUM, R. A. A. D. JCIRSHRNIUUM AND W. 31. ALBRECHT AND M.
5 W. S. HORTON 6 J. 1". HODGKRS
AND AND
A. V. GROSSE, Traws. Am. Sot. Jleluls, ‘15 (1953) MossnrAN AND A. V. GROSSI!, Trans. Am. Sot. Mefals, A. V. GROSSE, Awl. Ctwwr., 26 (rg54) 1955. W. MALLISTT, Atlal. Chm.. 26 (1954) 401. J. RRADY, ArlaC. Chem., 25 (1953) r8gr. G. J. HARTEH, Anal. Ctreprr., 26 (1954) 395.
l
758. 46 (1954) 525.
August
1st.
l()gG
16 (1957)
STARILIT~
THERMIQUE
DES
BTALONS
ANALYTIQUES.
IV
325
%USAlMMENFA,SSUNG Ln diescr vim-ten Arbcit hber Verglcichssubstanzen wurdcn die Thcrrnolysekurvcn und Ultrarotspektren im festcn Zustand von I 2 Vcrbindungcn bestimmt,wclchc in vcrschicdcncm Masse ZIII HcrstellunF: van anal>rtisch-chemischcn TitcrWsungcn dienen k&men. HIBLIOGHAPHIE Ii. J>UVAL 15-r J. LWONTJ~, Conrp/. rend., 2x3 (1941) (~9% C. DUVAL ET J. LECOMTE. Comfy/. rend., 272 (1941) 389 ct 696; Bull. SOC.chinr. Frcorre, S (1942) 548. C. WUVAL ET S. PELTIER. Compf. reprd., 220 (19411) 1727. Mllc DUVEAU, Diplhe d’&fths Supdriorres, Paris, 1042. Mllc C. ROCCHICCIOM, Compl. vend., 242 (rgg0) 2922. Elscvicr l~‘ublishing Company. :\mstc!rclarn, C. DUVAL, Incwgakc Thernropravimefric Arrdysis, 1953. 1~. 172. T. DUPUXS. Cotnfil. rerrd., 242 (1956) 2224.
EXTENSION 01; DETERMINATION
THE
ISOTOPIC OF OXYGEN
METHOD FOR IN TITANIUM*
THE
I,>
I?esearclr lnsliirr~e of ‘I’enrfile Unirtersily,
Philadelphia,
Pa.
(U.S.
.*I.)
The use of the isotopic method for the determination of oxygen in mctals1*!*3 has now been applied to titanium in the range of o.od-0.2 wt. Oh,O.I’his method is based on reacting a weighed sample of titanium metal mixed with a known amount of and liberating “master alloy” in the ~tzoilcn state with graphite ‘“O-containing part of the oxygen as carbon monoxide. The 1sO/160ratio in the carbon monoxide is determined by a mass spectrometer. Method
The percent
oxygen,
x, is calculated .2: =
where a
100
of calcrrlatio~r
from the simple mixture
bt(na-n)
-_--._
at&
-
(clr--rtv) . .__...- .___-_
a
rule, namely:
1
weight of sample; weight of titanium “master alloy” containing L weight fraction oxygen, with ??Iatom o/oof oxygen-x8 in excess of the normal** isotopic concentration (W 0.21 at. o/o leO); C _Z weight of crucible containing 21 weight fraction oxygen; (I weight of graphite containing v weight fraction oxygen; n = atom ()& of oxygen-r8 in excess of normal concentration after equilibrium. Because isotopes are preferably mixed and measured on an atom per atom basis, .-.-_. . _. .. b
=
l Presented before the Xnalytical Section of the American Chemical Society in Xew York, N.Y., Sept. 13. 1954. l * ‘The exact normal ,isotopic concentration is determined before each series of analyses.
Refersrks’p.
aa
A.
226
D. KIRSHEkBAUIM, A. V. GROSSE
VOL. 16 (x957)
61 should be expressed either in gram-atoms or, more simply, in weight units using the same atomic weight of the element as in a. Thus bt is not expressed in actual milligrams of the heavy isotope, but in equivalent milligrams of the normal isotopic mixture (see Ref. 1, p. 760).
The apparatus and proccdurc used wcrc clcscrihcd in detail prcviouslyr*2. Tt was found recently3 that by replacing the graphite crucible wit11 a molybdenum one (maclc from 0.25 mm sheet metal), tl~c oxygen blank correction can Gc rctlucctl from about 3 mg down to o.or mg.
Sn,,lplcs
N rrrllyzclc
The titanium metal samples wcrc supplied and analyzed by E. 1. du Pant and tlrc hllcghcny T.lctllum Steel Company by the vacuum fusion mcthod4.
de Ncmours
& Co.,
The data obtained by the isotopic method are tabulated and compared with those obtainecl by the vacuum fusion method in Table J. It is of interest that the vacuum fusion data are IO-IS%, lower than the isotopic values. ‘This would indicate that in the vacuum fusion analyses not all of the oxygen has been liberated as carbon monoxide and that some of the oxygen is held by the metal. This concurs with the findings of HORTON AND I~I~ADY~ who rccovcrcd only 85-7o”A, of the oxygen by the vacuum fusion method in the case of chromium. Similarly, RODGERS AND HAI~TERO using the same method, found that the recovery of nitrogen was not quantitative in analyzing zirconium metal. In their case the determination of nitrogen, in the form of ammonia, by the Micro-Kjeldahl method gave higher values than the vacuum fusion method.
OlSTlCllhllNATION
(In all cases j)d =
136762
012
OSYGEN
atom o(,reO,l /
u, g weight of suhstancc 6 weight of master alloy f: i- (1, g weight of grspliitc 11, atom, I<, llrO above ncxmal after equilibration
h,
#RI--_)I
.V = wt. OA, 0 in sample, observed * * wt. y<, 0 by vacuum fusion Wffcrcncc, o/O of 0 content, isotopicvacuum fusion
IN
TITANIUM
=
r .8o557 0.17860 2.7273 6.7534 6.9228 0.0483 0.0436 i-9.7
.-. ..-- -- -.-.-----.-.._--.- ._._. . _.._-- . ..-_.-._-~___-._--* Analyzed by supplier.
BY
THE
ISOTOFIC
MRTHOD
r.Sgr7wt.O~,Oandu=u
I .oosqr)
o*r3.)79 “.0)505 4~9772 8.6ggo 0.1378 0.1219
G2I.S
_...._ ..._._ -.
= o.rgowt.“/oO)
2.22325
2.2ISr)S
0.14674 2.328s 3.6417
cr.15474 2.2374
3.7352
10.0345 0.1870 0.165 j-1 1.8 _-_._
994ro 0.2005
0.175 -1_12.7
___---_-----
A possible error leading to a higher oxygen content by the isotopic method might be due to an exchange between oxygen-18 of the carbon monoxide and the oxygen-16 in the quartz. This error possibility, however. was shown in a previous publication2, to amount to less than 0.5% of the actual oxygen content of the sample. I
.
VOL.
16 (1957)
UETERhflNATION
OF OXYGEN
227
IN TITANIUM
The only other way the isotopic method might give erroneously high results is if air leaks into the apparatus. This would immediately reveal itself by the appearance of atmospheric argon peaks in the mass analyses. However, no argon was found in any of our samples. ACKNOWLEDGEMENTS
The authors wish to express their thanlcs to Dr. R. H. ~LlXKKNSlEIN of the Du Pant Company and to Mr. W. A. Psrrw~ of Allcghcny Ludlum Steel Company for supplying us with thr: titanium samples.
Our oxygen of 0.04 results found
method of isotopic elomcntnrv analysis has rcccntly been appliad to the dctcrmination of in metals. It is now cxtcnclccl to the determination of oxygen in titanium in the low range to 0~2 weight pcrccnt osygcn. Tho method has the great advantage that it gives qunntitativc wil/rorr/ a quantitative separation of oxygen in any form. In the !JitttlplcS analyzed it \ViW that the nltcrnativc vacuum-fusion m&hod gives results which arc g-130/” too low.
Notre m&hode isotopiquc tl’analysc &lbmcntaire a &6 appliquCc r&zcmmcnt ill1 dosage dc I’oxyg&nc clans lcs m&aux. Ella cst appliqu& maintcnnnt au dosage clc l’oxyg:c\ncrclans lc titanc. cn poitls d’oxygbnc. Ccttc mdthotlc prdscntc lc grand avantagc pour dcs tcncurs dc 0.04-0.27;, de donncr dcs r&ultnts quantitatifs SUNSsdparation quantitative rlc l’oxygbnc. Nous nvons constat& que, pour les dchantillons analysbs, la mdthodc do fusion tlans Ie vitlc clanne clcs rCsultats 9 Q 13%, trop faiblcs.
Vor kurzem wurdc unsure lsotopen-Methodc dcr Elomcntar-Analywe auf die Bcstimmung von Saucrstoff in Metallen angcwandt. Dcr Anwcnclungsbcrcich dcrsclbcn wurclc nunmchr auf dir: Bestimmung van Saucrstoff in Titnn, in dem nicclcren Bercich von 0.04 bis 0.2 Gcw. o/o Snucrstoff crweitcrt. Dcr grossc Vortoil tlcr Methode ist darin zu crblickcn, dass sic, olrrredie quantitative Ergebnissen Abtrcnnung dcs Saucrstoffes in irgcndcincr Form zu crfordcrn, zu quantitativcn flihrt. Es zcigtc sich, dass tlic Anwcnclung dcr altcrnativcn Vnkuumschmelzmethocle auf die Saucrstofflwstimmung in den untcrsuchtcn Probcn Wcrte licfcrt, wclchc urn g-13?<, zu nicdrig licgcn. REFEREKCES 1 2 3 4
A. D. ~~IRSHENBAUM AND A. D. I<;IRSHENBAUM, R. A. A. D. JCIRSHRNIUUM AND W. 31. ALBRECHT AND M.
5 W. S. HORTON 6 J. 1". HODGKRS
AND AND
A. V. GROSSE, Traws. Am. Sot. Jleluls, ‘15 (1953) MossnrAN AND A. V. GROSSI!, Trans. Am. Sot. Mefals, A. V. GROSSE, Awl. Ctwwr., 26 (rg54) 1955. W. MALLISTT, Atlal. Chm.. 26 (1954) 401. J. RRADY, ArlaC. Chem., 25 (1953) r8gr. G. J. HARTEH, Anal. Ctreprr., 26 (1954) 395.
l
758. 46 (1954) 525.
August
1st.
l()gG