VOL. 1 (1947) .\s.\r.\- I-ICi\ Cl11 AfTC.\ .\C’I-A l

301)

QUAN-I-ITATIT’E SP~CTIIOGRRPNICAL ANALYSIS OF

\YMITE-MET.41, USING SPARK 13SCITATION

l)Y

J . I s-1 I~ODUCTI OS

So far, on1.v i1 few invcstlgxtions llnvc: been pl~l)li4lcd cone_1 ning the qu:lnti- tativc spcctlograp11ic anal> 9i5 of complcs allo>*s, containing bcsitlcs tlw chief

clcmcnt, Iargc contents of other con.,tllucnts. On the one hrmcl, this IS tluc to the fact that, as a rule, 11~ cllcmlcnl an:ll\ws for thcsc clcmcnts. whose contents arc sufficicntl>* high, is comparati\*cly cask*, while, one the other hand, the hpcctro-

graphical tlctcrminatmn of the various clcrncnts 1s often strongly influalccd by the prcscncc of lligh contents of n third constltucnt, cspccially If thcsc contents ;Lrc apt to fluctuate Iwt\vccn \vitlc lrmits. \\:c arc*, nc\*crthclcss, of the opinion, that it

ma>. hc of great importance to csnminc wllc tlwr or nut a spectrographic method can lx applied to such alloys, cspccially from it practical point of \*icw, for csnmplc as IL clwck on tllc xvorklng proccsx~ in foundries. ‘I’llc main advantage of the spectroclicmical clctermmntion lie. nilInCl~, in 11s cluxkncss, xvliilc as a rule its prccislon, varying x.5 it clots in the niorc’ fnv~uinl~lc casts Ixt\vccn 2 :: and 3 0/O, will bc amply suflictcn t.

2. SUUJEC’I r\ND 1’URPOSII:

In the prcscnl study restricting ourwl\*cs to ;I dcfiniLc t!yc of tlic group of whitc- metal alloys, \vc ilIT only conccrncd will1 an allu?~ usccl I>!* tlic S.hr 13.S. (Xiltl0Iltll

Belgium Railways Compitny) as itntlfrlction rnctA, the coml,osition of which must ful!il tlic following rcquircnxnts

Base clcmcnt : Sn . All~~~ccl clcmcnts : Sl,

cu .

Imppuritics: Pi> As : Fc * %n

(Fc -I- %n *

Rq-fYcrrccs p. 2r7.

15

Foi tnorc &tail5 :~t)out the tr*rtle range of tt’lfIt.c-metal bearing alloys, xv:: refer to mart gcncral Ixqx_zrs such a.5 f\.S.I’.iX. (I~rsignation IZz3----4GT (1946) and DIN (1703 ancf 1707)).

‘I’l~c p-twposc of the prcscnt mvestigatton is to prove that the spectrographical mctI\ocl cna1Ac.s one to ascertain, with sufficient accuracy and within a very short lime wllctllcr or not ;L given alloy belongs to the type of white-metal Just dcscribcd :tnd satisfies the stanclardiscd demnncls, this being of great importance for the cliccking ~trxllysis previous to the founding.

In order to rcricIl tlic end, mcntioncd :~I>ovc, five st;tnclarclt~cd alloys wcrc formclotl. m whtcI1 111~ amounts of the tarious ccxxbtitucnt5 were mode to range so as to incluctc tlic white-mcla1 under csammation. ‘I’hc composition was accu- KklCip deLcrrt~inccl by C~lCllllCi~l amilysis. .A series of condensed-spark slxctra of c,~ch of tllcsc st~n&rdi~cd alloys was then rccordcd and in the qxclra tl)w obtained, the intcnslty-ratio w;ib determined bctwcen :t lmc of each clcrncnt, the contcnl of which was lo IJC found and CL lint of the base clcmen t. By plotting these ratios against the content of the clement in qucstlon, one obtains a set of stnnclard- curves, wI~IcI~ can then lx used for the slxctrograpllic mnulysis and for checking the type of the alloy.

4. PROCI:ET)ING

l’hc computed quantities of the constituents (pure metals) arc m&cd in a pxph itc cruciklc under :I Inycr of cliarcoal. After 1iaIf WI hour the contents are poured into n pan ; tlic alloy ol~t;~irlecl in this w,;y is rncllcd once agam without cllnrconl, nnd uftcr being \*igoroukly .stirrccl for a short time, it immediately is pourccI into a cold slcel clcct~odc-mould. T11c clcctrodc is crlinclrical, its length is 9 cm and ils cliamctcr x0 mm. l’lic inst;~ntimcous soliclificntion is meant to gunran- tee, a$ much as possible, a cc~nq~letc homogeneousness of the clcctrodes. this homogeneousness being of great importance.

l’hc actual composition of the cIcct~ocle~ was dctcrmincd by cl~cmicnl analysis, In or&t to avoid errors caused I,;* ;tnv possibIe inhomogcneousncss of the cfec- tr O&s, tllc Snmplc to bc ~Uli~lJ?XCl \V;Is tnkcn from plaCCS as CIOsc as 1xxssiIAc to thC plnccs Co 1x2 esaminc;cl spcctiographicnlly.

I. Arsenic i3 distilled xs &l-l, and introclxcd into :m csccss of an nlknlinc In,-

I&-fcvrr1ccs ,p. -“IF.

VOX,. 1 (1947) SP1:CTROC.R \PIIIC \I. .\X:.\l.\‘SIS OC \\‘I11 I’E 3II:T 11. 211

solution; after adding a solution of ammoniummolyl~dntc in sulLAruri:: acid, the cxccbs of I2 is clcstro~*ccl by X+!!,O, , reducing the niscno-inol~~lxlatc compound formed wth SnCI,, the solution acquires a blue colour, which makes 11 possible to find the As-contcut colorirnctrnxllyt.

2. l’llc sum of the Sb- and As-contents arc dctcrminccl by titrntlon with h;J3rO.,. 3. Sn and Sb togctlwr arc grnvimctrically dctcxmincd as osiclcs, from tliis

tlctcrmin;ition the %-content follows. 4. In tlw filtrntc of the latter the l’b- ant1 Cu-a mounts art! found clcct rolyticall~-

ilb PLO, and CU rcspcctivcly. 5. ‘I’lic Zn-content in tllc rcmitining scllutton I\ dctcrrninccl sl~~~ctI~,gl~~~~llic,~ll~~

nccording to LZn~ii~crr’s nictllotl (%nO in CuO-IMW)~. G. \\‘c lolmcl tltc I:c-c0iitcllt SC~~~ll’iltCl~ 1>\1 coloi inwtqf, using cr-a’-~lll)\~I’lCl!~ll.

CL. Excil2rt.q colk?illolLs. From a prcliminnr_v invcstigttion, in whicil tlio ilrC as

well as the sprl c wds htwlied. it nppcnrcd tllxt lnghly rcproduclblc csciting con- ditions fol wllilc-lwLa1 can Ix Ol)tillllCd bv means of tllc condcnsccl S]Xlrl<. \\‘u Usccl

i~Ul:SSSl~W’S hl’“rki~I’P”rilt~lS in the followkg working conditions:

Sccondnry voltngc PF4 (I2 000 V) CilpilCi t> C 3/5 (x800 cm) Scl f-induc t ion L I/I (So0 000 cm) Electrocks : lower-electrode * white-metal, 0 3.8 mm

top clcctrodc : graphite 0 3.8 mm distance hetwccn elcctrodcs : 3 mm shape of clcctrodes : standard SllilpC

(flat tulncd surface \vith sligthl> roundccl cclgcs)

I. By the above mentioned preliminary spectroscopic investigation using the: arc, we convinced ours& c.i that a rod of graphite used as upper-clcctrode yicld5 better results than two metal-clcctrodcs placed ol)posrte each other. ‘I‘hc same was found by other invcstigators3.

2. A strong snction apparatus (vacuum cleaner) is placed a few ccntimctcrs above the clcctrodcs (Zerss-stand in dc GR.\AIOST’S construction), which continu- ally supplies fresh air to the surroundings of the clcctrodcs; this method means a considerable improvement bf the results compnrcd with those of a former invcsti- gation. l?cfc~~rrccs p. 2rl.

3. Tn order to mnkc the dlxharge talcc plncc more regularly, we applied more- over EL sharp metal point, mounted horizunt~tlly at about I cm from the spark and clcctrically connected with one Of the clcctrodcs (“Lockspitzcf”*.

fl .S~cc~~#~~~~J~. All csposurcs were nwdc with the %I;:rss-spectrograph “Spck- tlograf filt Chcmikcr Q x8”. using quartz-optics. Slitwidth: 0.05 mm.

y. Iflu?ilinnlio?t. 11 uniformly illummation of the slit is obtained by using a three lens-system according to %i:rss press zG6 fr). An intcrmcdiatc image of the?’ light source is formed by mcims of the first lens on 3 screen mounted imme- d1atcly before t11c SCC0~lci lens. In the screen a variable apcrturc is mounted so as t0 isolate, If ncccssary, some part of the light, the wltulc npcrturc however \VitS tlSC!Cl.

Immctli,~tcly in fronl of tllc slit rotates a logaritllmic step sector by which a spcclrum, rccluccd in five stcpb, IS oblainccl. Provided the angular velocity be cctmputctl in the right \Vily, such 3 sector can, accorcling to Scii>tIIXG, be used quite well with intct mittcnt light-sources, 11kc the spark. ‘The sector was rotated by ;L synchronous motor at :L speed of 125 rpm; his ratio being 2, the ang:lcs coVcrcd by the separate steps arc 240°, Izoo, Go”, 3o” illltl 15” rcspcctivcly.

6. 7’tM.? of cx~OsliYc. Aflcr a prc-sparking time of 30 scconcls, which was fiscd cmpiricnllyO, the spectrum was recorded du~mg 75 seconds.

c. Under the conditions just descrihcd, G csposurcs xverc made of each alloy.

Plates : GEVAERT Supcrchromosn 25O, anti-halo. l~cvelopn~cnt : mctol-hydrocliinon, four minutes at 22O C.

The intensity-ratio bctwccn a line of tlte clcmcnt to bc determined and a lint of the base-clcmcnt was csprcssccl in terms of “cflicicncy-cliffcrcncc” de, intro- ChlCCd by BRECKPO’I ‘. This quantity was determined with the aid of the logarithm- icAy reduced .spcctra in the way csplairlcd by him. \Vfnlc taking into account the y (by intermittent ilhlminntion) of the plate at tltc very spot where the line is measured, this method mcnns a considcrablc aclvantngc over other methods.

The main constituent of the alloy, Sn, being prcscnt in suflicicntly high and Very slightly Hut tunting amount , was chosen as referring cicmcnt.

All measurements were carried out with a “%~:rss Scl~ncllpl~otometer”, the photomctcr sht being o.So mn-,; its sensitivity ~35 arrnngcd in such a way that the deflcctlon of the galvanomctcr lo1 a non-csposccl part of the plate amounted to So0 scale-divisions.

VOL. 1 (r947) SPECTROGR,\I’IIIC~\L .\Sr\I.YSIS 01: \VIIl’I-1: ;\lI:‘lr\L 2x3

f. .*l mljtsis lines

l’hc following lines wa-c found to lx the most siiitnblc for tllc :lIlillJ’Si>:

{

Sl, 2G52 Go

c

1% 2373.32

C

Fc 2522SG

Sn 2GGr.25 Sn a7Gr.S Sn 2523.91

{ Cu 3961.16

{

A\ '349.53 Mn 3345-G %I 314I.SI Sn 23GS.3 1% 3223.7

5 I(I3S II I.‘I‘S

‘J’nl~lc I hlio\vs the rc9llts nf cl~crn~c;~l ;~rial~bis. Jksitlcs tltc content of cad1 constituent per 100 g of tlic allo>* (;~l~holutc content) \VC 11a\c ntldct1 its amount per x00 g tin (rclnti\c content).

:‘;, 51 -I--- ;1l;s.

-7 .-.-

T _.- _.___. -- _---.-._ _-_- __ ---. . __ -.-_--.- ----_---.

‘I:, SI, “,, Cl1 u:, 1’1, ” \s 0 1 I:,, ICC I:,, x11

- ---- --_- - ---- -- -- -..- -- - .- - ---_. _._ --- - --. --- .

;1bs. rcl al,s t-cl. dl,S. rcl. ah. rvl .ilPi rcl nLh rcl _ ---_ -___ ----- -._- ---__- --- -__-_. .-_-.- -.-----.-__ --

I II.51 IJ CJs 4 7b 5 73 0 .I')') 0 002 0.17') 0.2IC 0 02s 0.".~_37 o.u27 0.03~3

10.X.) Il.96 123 I 90 0.87 I o-5 OILY o.151 - - 0.0.18 0.~1566

x1.87 I.) 7s 6 47 7 73 0 72 J 0.328 O.IS.5 0.217

L

0.05 I 0 05’Jh - -

x0.3.1 '2 15 5 s.: 7 ox - - - - - - - - rz.G8 ‘5 37 *I OR I ., HS

- -- -I_~.~~ - L Z.-I_ - Spcctrographicnl data arc collcctcd in ‘I’;~ldc f I. leach 1 alllc of At is tllc nritll-

mctical mean of G nicasurcnicnts (6 pliologr;~plicd spectra). ‘1’11~ avcrngc tlcviationh 6 hnvc been adckc~.

Fig. I, 2, 3, 4, 5 and G sliow the working cur\*cb. ‘1‘11~ cflicicnq*-difkrcncc is plotted against tlic log of tlic vclnftrc content of tlic clcmcnt in cluc5tion. l;or 19, As, Fc and Cu the sprcacllng of the lxkts is \*cr>* slight., for Sl, it is SoIllc\vllitt larger. ‘J’hc cur\*c for XII IS ratllcr flat, \vl~icll is due to the \\cnI;ncs!, of tllc Zn-line for the minute conccntrnliqn here consiclcrccl.

RcfwotZltciDilify. .4s appcnrs from the a\*crngc tlcx iationb, tlic rcl~r0d~tcil~illty reached may lx callccl vcr>* satisfactory. ‘l’l\c ?/iCRtL CJ’1’01’ 7/l of tl1c cfficimc~*-clif- fercncc of one single mcasurcmcnt for the various clcmcnts is sllou\n in ‘J’ablc III. It is computed by IllC!ilnb of the csprcssionH

---- _ - ,.z\z

Ill = l / --

n-u

zr4 .I. l.Il.LIS. J. I:J:CICI!CJU’I’, AI. V.\h 1>00J~bI~J.r\l:J~ 1’01.. 1 ('947)

L f -- 03% 10%

- --c Log%Pb WI

Fig:. 3. \\‘orlclllg Llll \‘c TOI 1%

+ -050 -

003% 006% --*Log%Fe ret

1:1g 5. \Vorlc111g wr\-c for 1%

12l~fcwrrcl3 /L 2 I 7

I I,

01% a25% -cLog%Ap ml

1;1fq, .I \\'orlclng curve for As

Ar 1

003% 006% -Log%Zn ret

1'16. G. l\'orlcing culvc for Zn

VOL. 1 (1947) Sl’ECTI~OC;I~.\PIIIC.\L .\S.\l.\‘?YIS 01: \\‘IlITE >11:1 \I. ZI 5

whcrc v = ddfcrencc of the inch\-iclunl mcnsurcmcnts from 11x2 nritli- me tical mean ;

n = number of olxcr\*ations (= numlxr of sIxxtr;l on wliich Llw mcasu rcmcn +* wcrc cnrriccl out) ;

u = number of qunntitics (= number of stancl:~rd points).

In the GAIjSSi:m distribution 50 (i/0 of all mcasurcnwnts li,ivc errorb 1ilrgCl’ tllan “/3 m; this is, thcrcforc, tllc wluc of tiw pvo6nbf~ CIYOY w, w111cl~ 1s al.so insert in tlw table.

Taking into account the blopc of tllC \vorking CllI’\‘C (tgcz) ilTl<! tllC filCtOr p,

rcplchcnting the ratio Ixtwccn tlw Iinith of absc~s~:t ;111d ortlindtc, 011~ ~111 compute from w the prol~aldc error / of I//c co9hxl in y:, , ;tccordlng lo

l’hcsc errors arc sliou-11 in tllc last column of tlic table’. iTo1 Sb, C11, PI>, 11.s ant1 Fe, tllc~ arc wry smdl; for Zn, lio~vc~*cx, tllc error 15 I:trger tlils is \Vlioll\ clllc to tllC SIllill SlOpC Of tllC cur\*c, ily wliich an ilCCllrilt 2 ~~~~tCrIl~iIl~lti~JI1 Of tile %Il.cOntCnt

is made imposb I MC. ‘l’lic mnsimum content of Zn. t~lcJllgl1, cd11 1x2 found from 11 fairly ZlCCUriltCly.

AlKll~SlS

lines

b 2652,Go n aGGr.z5

b 2873.32 n 2761.8

9 2343 3.1 lI 2368.3

c 252z.SG lI 2523.91

” 3345sG p 3223.7

T -- AL

-- - b’

- 0.7.12

-0 119

-o.f.)r

- 0.5ss

- 0.7.10

-I- 0.0 I 7

I .L

o.oog

0 00s

0 005

O.OO(J

0 010

0.011

-.

.- I

I

--_. ,\I lay .! -r .

-

.-.--- LI 4

~-

- “-74 I

- 0. I(‘G

-I- o.u5 I

- 0.721

--

+ 0.05; .-

b’

o.ooj

0.030

0 012

0001

.-

0 006

--

-_- Ar

- 0717

- 0 315

-- 0 405

-” 5Sb

-” 552

.-

.- ..- R

---

0.00,

0 VI I

0.c IV

0.007

0 OOf8

-

--

.

1 -- r --__ L-__...

r\llo) , Alloy 5 --

i

‘--I--I--- AI I4

- cl YOCJ 0.00,

-- o.3zH 0.007

- -

- -

-.. I --

I _-

I -l--I_ -.- -- -.

_.~

- 0.702

- v..~Gr

-

-

-

-.. K

0 00s

O.OfJ2

-

-

-

-

--

If one wants Co Iind out s~~ectrogr~~~liic~ll~ \Vliutlicr or not an unkno\~ll ~vliltc- mctnl belongs to the t>‘pc in\xstigatccl, the cfficlcnc>*-cliffcrcncc for tltc gi\ul udysis lines must lie bctxtcen &finite limits:

I~cjcroIccs 1’. 2r7.

2IG

Sb -0.72 > Ar > -0.78

CL1 ------0.295 > At > -- 0.35

7’1, AL < --.o.rr,

11s da <\ ---0.5ri5

ITC AC < --o&3

%I1 Ar: ._= -I- 0.055

‘I II(*cc~ Illnils arc sl~o\vri in tlic figurc:s 11). clottctl lines.

-i

I- ‘-

-

y\ 2 ‘/ IOn

.---__

I.\37

3 w_J

1671

107)

710

11.1’

--

II

-.. ._

26

2 ,

‘5

‘5

8

ICI

‘I’:\Izl.l: I I I .- _ -- - .-

II III

- .

5

5

:1

3

?,

2

. ..--.

3 OCJS

0 (Jr.37

OOIIH

o.oor)f;

0.01 I

0.01 .! --

\\’

_... .

O.OO.j.(

o.oogr

” “073

0 ooG3

o 0073

0 oo7G

-.--

-

1RU

__-___

0.83

r -3 -7

0.916

I .?I

I.30

0. :! -3

vol.. 1 (1947)

--_-

I’ _.

‘I2

3l1

‘I,

‘la

‘I3

‘la

--.--

I

- _-----

I .., ‘:.:,

2.2 ‘i’”

2 .o %I

2 ..I y4

2.G y/o

1L.f “6

a. III 11112 prchcnt inwstIgnLion Llic pxs~l~~l~ty I+ shown of dctc~ nlintng spcctrogr.~plllccllly for ,L wliitc-mc1.d. I. tl1c Illlllts. bclwccn \vliILIi tlic pt lncllx~l LoniponcnL\ of ‘1 wliltc-liict,tl arc illlCJ\VCd to vary; 2. CIIC nx~s~miiili ~011lcr11s of 111~ impur~l.ws.

b. 'I'hc iiwllmct IS tlcwr1l~2tl III tlct.~ll .knd tl~c nt31 Iany: CIIT\CS ;LI L’ SIIOW~ :I+ well for tllc lIllpUIILICb :I?! lo1 tllc ClllCf corlsll~llcIlts of tllr ;tlloy (Sl) :1ntl Cu). ‘1 IIC lllrtllocl 15 sllllplc .md quick and, t,tlclng iii10 :lccoulit 11s iatlicr 111gl1 ;wxr.xy. It* .l~~~~llC.ltl0fl LLll IJc Of grCitL USC

III found1 ICS, WIWIC ;~~~.~lyb~h must bc carrlccl out 111 \crlcs cvc~y tlxy.

lhns In pr6scnlc tlutlc n011b ;LVOIIS montr~ quc l’.~nnlysc spcctrnlc pcut wrvll CL clSLcrnilncr clans III2 IlltLll LIlilllL. r lcs pourccntagcs cll~s tl~ll~~cnls constIL.u,tnts ct Its I~rii~tcs cnlrc lcsqiicls ccs pourccntdgcs

pcuvcnt v.lrlcl , 2. Its coiicciil.lntioiis tics Ilnplrct& 1st Its conmiitr.~Clons Illi1SIIII~L ~cl~ii~bh~l~l~~s

La nl6lllorlc CSL cltcrltc cn clCL.~il ct Its COIII~CS clc tlchtgc ont cti. clrcss6cs pour Its constltu- xnts clc l’.dlingc (Sb ct. Cu) vi+;l-vh clc I’ktoln coniliic hsc, nlnsi quc pour Its lmpurctbs d’un type cl&cruxrnG clc m6tnl-b1,~11c.

Lx mbtliodc est. s~niplc ct r,lpidlc ct, vu 1.~ 11;1uCc pr6cislon oblcnuc, cllc pourrd rcnclrc scrvtcc clans l’lnclustrlc, pnr cscinplc pour Ic cotiLr6lc clc fnbrlcntion. h’rfcrr tzcc< p. 2r;.