The sample is treated with 5N H2SO4 followed by concentrated HNO3 and the diluted mixture is filtered. Soluble B is determined in the filtrate by Inductively-Coupled Plasma (ICP) spectrometry after addition HCl and extraction of Fe with ethyl-ether. The residue is fused with Na2CO3 and, after treatment with HCl, the insoluble B is determined by ICP spectrometry as before. The method permits determination of ppm amounts of B in steel

Coedo, A. G.

Lopez, M. T. D.

Revista de Metalurgia

English

A method is proposed for boron determination in steels at ppm levels by inductively-coupled plasma spectrometry. Solutions equivalent to 5 g sample in 100 ml were used, a previous separation of iron being performed, in HCl, with ethylic ether. The analytical line used for boron analysis was 2496. 78 A and the results were verified with standard samples.Peer reviewe

Gómez Coedo, Aurora

Dorado López, María Teresa

Digital.CSIC

Boron Determination in Steels by Inductively-coupled Plasma Spectrometry (ICP)

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https://ntrs.nasa.gov/search.jsp?R=19860019554 2020-03-20T14:51:03+00:00Z
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
'WASHINGTON, D.C. 20546 	 JUNE 1986
^r
	 07
r
NASA TECHNICAL MEMORANDUM
	
NASA TM-88434
BORON DETERMINATION IN STEELS BY INDUCTIVELY-COUPLED PLASMA
SPECTOMETRY (ICP)
A. Gomez Coedo and M.T. Dorado Lopez
Translation of "Determinaci6n de bozo en aceros
mediante la t@cnica de espectrometria de plasma
(ICP) ", Rev. Metal. Vol. 21, No. 2, March-April 1985,
Madrid Spain, pp. 87-90
NNASA-TM-88434) 60RON 9ETEEYjINA7I0N IN
	 N86-29026
STEELS BY INDUCTIVELY-GCUPIEU PLASMA
SPECICMEZRY (ICP) (National Aeronautics and
Space Administration) 14 p
	 CSCL 11F
	 Unclas
G3/26 43456
LTANOARo TITLE FACO
1, Ra••rt He.	 !. Wnr*w•M Aaa•sel•e N•. 3. R•clPlet► t's C400100 N•.
NASA TM- 8434-
4. 	 Tltl• •n4 SY► itale S. R/yar Date
Boron Determination in Steels by induct JUNE 1986
ively-Coupled Plasma Spectometry ( ICP) 6. P+rI•rnlnp 011enilotien C•I•
I	 I.	 Awfhor(.) 04 P/rlernino Drfenalatlen R.,•.1 too.
A.G.  Coedo and M.T.D.  Lbpe z
14. Welk unit Ito,
11. CGnarect of Grant No.
0.	 Pertere.,ng Drlenil•ti•n Items rill AJJ*o#e NASw•	 4004
SCITRAN I>. Type of Raperr end Ae11 04 Cea•ra^
Box 5456
antaS	 Barha Translation
tat. 
s^Clonar eroaisutics aand Space Adminiat ration
1Nasnindton, D.C. 	 20546 14. »i"oodog Ap•a-iy Codo
If. 6"PI•raent•.y Notes
Translation of "Determinacibn de boro en aceros mediante la
t6cnica de espectrometria de plasma (ICP)", Rev. Metal.
Vol. 21, No. 2, March-April 1985, Madrid Spain, pp. 87-90
16. Abotmo'
The sample is treated with 5N-H 2 SO 4 followed by conc. HNO 3 and
the diluted mixture is filtered. Soluble B is determined in th
filtrate by 1CP spectrometry after addition HC1 and extraction
of Fe with ethyl ether. The ::esidne is fused with Na CO and,
after treatment with HC1, the insoiuble B is determinid Zy ICP
spectrometry as before. The method permits determination of
ppm amounts of B in steel.
IF. R•P
 1706I• (S•16044 01 A(1 044Q)
	
10. ofstributt•n State""
Unclassified and Unlitiiited
1!, Sasr.lep Cta: N1. (•1 OA1• fAV40rd
	 D. sovVity C10610, toll ail• Peiz'1	 M no. of Pgao	 211. PAOa
Uoclassifled
	 Unclassificd
	
13	 i
Boron Determination in Steels by Inductively -Coupled Plasma
Spectometry ( ►CP)*
A. Gomez Coedo ** and M.T. Dorado L6pez**
C.D.U. 543.5:546,27:669.15 = 60
Abstract A method is proposed for boron determination in
steels at ppm levels by inductively-coupled plasma
spectometry. Solutions equivalent to 5 g sample in
100m> were used, a previous separation of iron being
performed,	 in HCL, with ethylic ether.	 The
analytical line used for boron analysis was 2496.78 A
and the results were verified with standard samples
from the British Chemical Standards.
1. INTRODUCTION
/g7***
Boron steel alloys, known for several decades, have been
reintroduced in the past few years, thanks to technological ad-
vances favoring their correct preparation, as well as various
studies concerning their properties (1).
Boron steels have been specified by the various
standardizing agencies: ISO, UNE, AIS1 1 AFNOR, DIN, etc., and
there	 are	 hundreds	 of	 varieties.	 The majority of boron steel's
are	 alloyed with manganese	 (:	 1%) and with chrome (<0.5%) and,	 in
some cases, with nickel and molybdenum.	 Carbon content varies
between	 0.1.5 and 0.45%.	 Aluminum and	 titanium are routinely	 used
r-espectively as	 deoxidizing	 and	 denitriding	 agents, with	 a
*rStud.y received November 29, 1984
** Dr. of Chemical Sciences. Member, CENIM.
Rev. Metal. Madrid 21 (2) 1985
***Numbers in margin indicate foreign pagination.
consequent residual content of these elements in the order of
0.030%.
The considerable interest in these steels is based on the
fact that small amounts of boron (in the order of ppm) improve
tempering to a much higher degree than other alloy elements.
There are various theories to explain the effects of boron
in improving the hardening of steel 's. This effect diminishes as
the carbon content of the steel is increased, and is practically
eliminated in eutectoid alloys.
Because of i is h igh of f in  ty f or n 1 trogen and oxygen, and
its readiness to substitute for the carbon in carbides, it is
accepted that a large proportion of the total boron present in
steei is made up of oxides, nitrides and/or borocarhides. By
selective chemical attack, it is possible to distinguish the two
types of boron present in steels:
	
soluble and insoluble boron.
Although the complete separation of the various boron
combinations is difficult, it is generally accepted that:
- the soluble boron component includes the boron of the
solid solution, the borocarbides, M2.3(B,C)6 and M 3 (B,C), and the
boron oxides. This boron component is placed in solution by acid
attack.
- the insoluble boron component is made up of the boron
Piiiri dos , BN. This component is placed in solution by means of
alcaline fusion of the acid-insoluble residue.
It is fully established that there is a direct relationship
between the improved temperability produced by boron and the
amount of the element present in the form of soluble boron. This
.a
2
relationship goes through a maximum, in that there is an optimum
soluble boron content at which temperability is highest, compared
to an identical material without boron (2 and 2)(Fig. 1).
As can be observed in Figure 1, all the authors find an
optimum soluble boron content, located between 5 and 30 ppm. The
differencess among these values can be attributed both to
variations in analytical methods and to different levels of
oxidized boron, taken to be soluble boron, although it exerts no
influence whatever on temperability.
There are certain clearly established facts with respect to
insoluble boron:
- the content of insoluble boron increases as the content of
fnitrogen (BN) increases.	 --
.j
4f	 ^' 	 k	 3G
25	 f	
GROSSMAN
.!	 MELLOY
0	 MAITREPIERRE
Z	 KAPADI4
LLEWELLYN 1
^j	
L	
L (^,	
L
0	 Q5Z D,DD4 0,006 D,O68	 0,010
CONTENIDO DE 8080, Re %
Fig. 1.	 Influence of boron on temperability according to various
authors. The maximum effect is set equal to 100%.
1- Influence of boron given as a %; 2- Boron content, %.
- the effect upon temperability will decrease to the point of
disappearance if the insoluble boron component is increased at the
cost of a diminished component of soluble boron.
3	 :4
low-
^S
C
x'
E
boron content levels we are concerned with.
.:1., : LSrc k
the presence of a certain amount of insoluble boron (from
10 to 15 ppm, for example, seems to improve the tensile strength
of steel (3).
From the foregoing considerations it can be deduced that the
content of soluble and insoluble boron can be used to improve both
temperability and tensile streri-th.
It is clear that the soluble boron/insoluble boron ratio is a
function of the content of free nitrogen in the metal, and
therefore, of the content of elements, such as titanium and
aluminum, which can form nitrides.
It ik--, of utmost importance to achieve a homogeneous
distribution of the boron, as gaps can create I or , aI
irregularities, such as sizeable oxide or eutectic formations (Fe=
C-B).
The difficulties encountered by the first manufacturers of
boron steel are now history; modern production methods make it
possible to ensure ar, even distribution. This leaves us free to
focus on the problem of providing analytic methods which will, in
turn, guarantee the actual content of this element.
The most widespread methods for this type of analysis are
included within two categories:
	 spectrophotocolorimetry and
emission spectroscopy (arc or spank). The former methods (4-14)
present major difficulties because of the extremely critical
working conditions under which they must be carried out, and the
latter,
	
in addition to being subject to the availabilty of
suitable master samples, do not offer sufficient precision for the
y,	 {
4
In this paper, the problem is studied using the Inductively-
Coupled Plasma emission source technique (ICP-AES)(15-20). An
operating procedure is established to permit precise, exact
determination Qf ppm levels of boron (soluble and insoluble) in
steels.
2. EXPERIMENTAL METHOD
2.1.	 Selection of analytical lines
2.1.1.	 Sensitivity
The study was made using etonventlonal ultraviolet boron
analitical lines.
X,A
2497.73
2496.76
2089.59
2088.93
	
Since the equipment utilized has no vacuum system (it merely 	 x
permits purging of the monochromator with inert gas), the remote
ultraviolet boron lines (	 = 1826.4 A and 1825.9 A) are not	 4
sufficiently sensitive for the boron levels we are concerned with.
r
On the other hand, it is of interest to note that these lines are
clearly interfered with by the 1826.3 A line of sulphur.
Table I shows the peak/baseline ratio of the lines considered
(calculated with emission values corresponding to 0.1 ppm of boron 	
S
and to water), the equivalent baseline concentration (concentra-
tion of the element which gives an emission intensity over the
baseline of the same order as the baseline itself) and the minimum
determinable ppm. The Relative Standard Deviations(RSD) calcu-
lated on 20 determinations of these minimum ppm are below 1%.
5
6The working parameters of the equipment employed OY 38 P),
were se iec'ted with the purpose of obtaining, for each line,
baseline values (considering as baseline the emission
corresponding to water) of less than .1,000 mV.
X tdai6n p Utfnndo
Or► PPM atH.o	 1
CE F	 1	 iPm 1nir^u+tiu
IVPmX	 Z	
Itt	 ur^bkt
2497.73 2,5 0,060	 0.03
2496.78 2.3 0.060	 0.05
2089,59 1.6 0,12	 0.10
2086,93 1.6 0,15	 0410	 i
Table 1. Sensitivity study of selected boron lines:
peak/baseline ratio, equivalent baseline concentration (C.E.F) and
minimum determinable ppm.
i- Peak/baseline ratio, 0.1 ppm B/1. 1 20;	 2- Minimum determinable
ppm (RSD 1%).
2.1.2.	 Interferences
Next, a. study of spectral interferences was made, in order to
verify the analytic value of each of the lines considered in the
determination of boron in steels. This study included not only
those interferences caused by the base element (iron), but also by
the other elements usually present in this type of material.
2.1.2.1
	
Interferences originating_ from the base material (iron)
Because of the high proportion of sample in solution
necessary for the precise recording of the boron contents of
interest to us, the direct sample solutions present a high saline /89
concentration which originates on the one hand, significant
nebulization and transportation interferences, and on the other, a
considerable increase of the spectral baselines, carrying with it
a diminution in the peak/baseline ratio, and consequently less
'^	 1
'^	 f
I r'I
1
favorable values for the determinable minirnum contents.
Because of these difficulties the process evolved included
massive elimination of iron using ethyl ether. Following this
process, described in Section 3, "Preparation of the Test Solu-
tion", it was verified that, for weighings of 2.5 g of sample,
with a final measurement at 50 ml, the concentration of iron
toatning unseparated was In all cases less than 50 ppm. Next, a
study was made to verify the spectral interferences produced by
this residual quantity of iron in the boron analytical lines.
Lines 2088.93 A and 2089.59 A in their next measurement showed no
significant emission from iron. Line 2496.78 A, although very
close to the iron line 2496.53 A, was not interfered with
appreciably by the residual iron, thus verifying that the emission
corresponding to 0.1 ppm of boron is not affected by the presence
of up to 100 ppm of iron.	 Finally, line 2497.73 A proved to be
affected by iron line 2497.82 A, even at the residual levels of
unseparated iron in the solution.
Table II showG the values corresponding to the emission of
0.1 ppm of boron in the presence of different quantities of iron,
in lines 2496.78 A and 2497.73 A, since these are the lines
located close to each of the iron lines.
Table 11.
	 Spectral interference produced by iron.
X
J„	 Valoms de emisi&
H=o 0.1 ppm 9 0.1 ppm 0 0,1 ppm a 0.1 ppm 0
+50 ppm h +100 ppm +250 ppm re
rV
2496.78 500 1180 1190 1182 1250
2497.73 800 2125 2250 2520 4800
As can be observed In table 11, boron line 2496,78 A is not
spectrally influenced by the Iron remaining after the extraction
process.
2.1.2.2	 Interferences caused by RjjX 21herelements p
--- ------ .— 
_LSISnt
The elements usually present in steels as alloy or residual
materials, cause the spectral Interferences shown in Table 111.
Tungsten causes spectral Interferences In the four lines
considered, making necessary its elimination during the
preparat lo,, of the test solution, by means of ammonlacal washing
of the residue in acids.
Though lines 1825.9 A and 1826.4 A were not studied, the
literature indicates a clear interference coming from the 1826.3A
sulphur line.	 On the other hand, it has been observed that
cobalt presents an emission in the testing of the boron 2496.78
I !ne t an emission which does not cause appreciable interferences
within the concentration levels tested.
Table	 111.	 Lines of the elements
	
interfering In the
determination of boron
at — L	 Eicrmnifjs iniefferento	 11A, A k A
Ni — 2089f18
2088,93 W — 2089,14
f
Mo — 2089.52
2009,52 W — 2089J4
2496.78 W — 2496,63
2497.73 W — 2497,50
I- Interfering elements.
8
0AP-'r
i
concentrated to approximately 10 ml and diluted to 50 ml
	 with
water.
	
This solution contains soluble boron and
	
is equivalent
	 to
Cinall^ ,-, and in considerat.io;,
 )f the sensitivity and
interference studies carried out, the boron 2496.73 A 1 ine was
selected for determination of this elernent in steels.
3 PREPARATION OF THE TEST SOLUTION
2.5 mg of sample	 is weighed and attacked	 In a teflon	 vessel
with 20 rnl of 5N sulphuric acid. When the reaction subsides,
	
the
solution is oxidized with 10 ml of concentrated nitric acid. The
resulting solution is diluted with approximately 23 ml of
[omitted] and is filtered while hot: through medium porosity
paper, washing it	 with with	 1	 to g diluted	 hot	 hydrochloric acid.
Soluble	 boron i;	 ., etermined in the	 filtrate	 liquids, and
insoluble boron, in the filtered residue.
3.1 Soluble boron
After attack of the sample with acid (Section 3) the
resulting solution is concentrated to approximately 15 ml; 30 ml
of concentrated hydrochloric acid is added and it is transferred
to a decanting funnel or plastic flask, using as a washing
liquid, 20 ml of 1 + 1 diluted hydrochloric acid (the chlor-
hydric molarity of the resulting solution falls between 6 and
8111) .
Then the iron is extracted with 60 ml of ethyl ether. With
agitation for 1 minute the aqueous phase is separated, and
another treatment of 60 ml of ethyl ether. The aqueous phase is
s3.2 Insoluble boron
After	 4	 tack	 of	 the	 sample with acid	 (Section	 3) the
resulting	 solid	 residue	 is	 washed with ammonia,	 roasted In	 a
platinum crucible	 and	 fused with	 IS anhydrous Na 2 CO 3 .	 The fused
mass	 is	 extracted	 with	 15	 ml	 water and	 5	 ml	 concentrated
hydrochloric	 acid,
	
and	 diluted	 to 50 ml	 with	 water. This
solution
	
contains	 insoluble	 boron and is	 equivalent	 to	 5 g of
sample	 per	 100 rail.
4. CONTROL. TEST	 J90
The analysis was paralleled by a control test using the same
proportions of reagents and following the entire operating
procedure for both soluble and Insoluble boron.
5. TERMS OF REFERENCE
The terms of reference for both soluble and insoluble boron
are prepared by adding ppm of boron from a master solution of this
element to controls containing the same reagents in the same
proportions as in the problem sample. Given the linearity of the
technique employed and on the basis of the small contents sought
to determine, these terms can be the control test and one which
contains 0.5 ppm of boron in an identical medium.
6. RESULTS AND CONTRASTING SAMPLES
Using the test solutions prepared according to subsections
3.1. and 3.2. against the respective control tests (Section 4),
and calibrating the results as indicated in Section 5, *he soluble
and insoluble boron content in the sample (as a function of the
minimum determinable ppm indicated in Table 1) can be determined
A
jY
10
7
with precision and accuracy down to I ppm.
The method developed has been contr ^bted with master samples
f rom the f i rms BCS (Nos. 326 to 330 and 458 to 460) and NBS (Nos.
361 to 365), the total boron content of which varies between 5 and
100 pprn. The results are given in Table IV. These same samples
have been analyzed for both soluble and insoluble baron by spec-
trophotocolorirnetry, and the results are in agreement with those
yielded by the method developed.
Table IV. Results
1 Munsru	
M 
bwo olubk
ICP
ppm bam bWWW
ICP
WP kWO t'"I
(a nW1C& a)
BCS 326	 802 4.0 10
00 327	 27.8 111 30
BCS 328	 39.0 2,8 40
BCS 329
	
71.1 10.0 80
BCS 330	 72.7 <0.5 70
BCS 458	 38,B 817 45
BCS 09	 91.6 8,2 100
BCS 460	 11,9 15.0 25
ppm boro total
i►proximado
(no certificado)
NBS 361	 0 1.0 5
NBS 362	 30.0 e-045 25
NBS 363	 14,2 0.8 10
NBS 361	 120,3 <0.5 160
NBS 365	 015 <0.5 —
1- Samples; 2- ppm soluble boron ICP; 3- ppm insoluble boron
ICP; 4- ppm total boron (certified); 5- approximate ppm total
boron (uncertified).
11
t
7 . OOKLUS IONS
- A plasma (ICP) methodology has been perfected for
determination of boron in steels at levels in the order of ppm.
- The soluble boron and insoluble boron present in these
materials have been separated by a wet method procedure.
- The iron matrix has been for the most part eliminated by
extraction with ethyl ether in a hydrochloric medium = 8M.
- The validity of the method has been verified by comparison
of its results with those obtained by spectrophotocolorlmetry in
various standard samples.
7	 ^
3
12
REFERENCES
I	 T1.IELNING, K,E.:	 Steel and its
--
	 treatment, 2d Ed.,
Butterworth, London^^1 m) 	 — —  — -- —_— —
2	 LLEWELLYN, D.T. and COOK, W.T.: Met Tec yhnp_l., 1 (12), 1974:
517-519.
3	 ROUSSEAU, D.: Aciers Saec, No. 44, Dec 1978: 9-18.
4	 PASZTOR, L.: Anal Chem, 32 (2), 1960:	 277-28:1.
5	 EREMIN, YU-G.:	 Zavod. Lab,, 29(4), 1963: 420.
6	 HARRISON, T.S.:	 Analbt, 91 (1.086), 1966, 576-581.
7	 BELL, D. and McARTHUR, K:Analyst, 93 (1.106),1968:298-305
8	 VERNON, F. and WILLIAMS, 3.M.: Anal, Chim. Acta, 51 (1970):
533-535.	 _---»	 _
9	 GLAGIARDI, E. and HOLLINGER, W. MikrochimActa, 1 (1972):
136-144 (a) .
10	 AFNOR. A 06-355 (1976).
11	 SAMSONI, Z. and SZELOCSKY, M.: Mikrochim,Acta 1, 5-6 (1960):
445-453.
12	 DONALDSON, E.M.: Talanta, 28(11), 1981: 825-831.
13	 OSHIMA, M. and FUJIMOTO, K.: Anal Chim Acta, 134(1982)73-80
'	 14	 VIALATTE, B and ALEVEQUE, a.: Analisis, 11(9) 1983: 446-451.
15	 HAMNER,R.M. and De'AETZ, L.A.:Talanta 27(6) 1980: 535-536.
16	 GRALLATH, E. and TSCHOEPEL, P.: Fresenius Z. Anal Chem
302(1), 1980: 40-51.
	
--------_   
	 __--
17	 DePARADE, D. and DOERFFEL, K.Z.: Z. Chem 22(9)1982:339-340.
18	 WALLACE, G.)~.: Atomic 'Seectrosc t 2(2) 1981: 61-64.
19	 FOS TER, R. and NYGAARD, D.D.: I CP Information        Newsl e t t e r 9
_ _ ___(7) 1983. 424.	 ___ ____ __ ___—__
`j	 20	 NYGAARD, D.D. and CHASE, D.S.: Res/Dev, Feb 1984: 172-174.
13


Boron determination in steels by Inductively-Coupled Plasma spectometry (ICP)

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