Mass and emission spectrographic analyses of magnesium oxide and tantalum carbide to determine impuritie

Leipziger, F. D.

English

NASA Technical Reports Server

RE-ORDER N O . d a -  
R,' v SRRC-RR-65-111 
This work w a s  performed for the Jet Propulsion Labodmy, 
California Institute of Technology, sponsored by the 
National Aeronautics and Space Administration under 
Contract NM7-100. 
DEVELOPMENT OF CHEMICAL ANALYSIS TECHNIQUES 
FOR 
ADVANCED MATERIALS RESEARCH PROGRAM 
Fourth Quarterly Progress Report 
covering the period 
September 1 ,  1965 t o  November 30, 1965 
JPL Contract No. 940992 
Prepared for: Jet Propulsion Laboratory 
California Inst i tute  of Technology 
4800 Oak Grove Drive 
Pasadena , California 
Principal Investigator: 
I 
Fredric D .  Leipziger 
I 
L ICATEGORY) 
(NASA CR OR TMX OR AD NUMBER) I 
/ 
I 
1 S R R 
GPO PRICE $ 
CFSTI PRICE(S) $ 
I 
I 
i 
I 
Hard copy (HC) 
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ff 653 July 65 , 
https://ntrs.nasa.gov/search.jsp?R=19660007403 2020-03-16T23:07:43+00:00Z
Development of Chemical Analysis Techniques 
For 
Advanced Materials Research Program 
-4 SL REORDER No. L s  
I .  SUMMARY 
The period covered by t h i s  report  has been devoted t o  a s e r i e s  
of i m p u r i t y  analyses on MgO and TaC materials.  The materials have been 
both powders and compacts. 
determined. 
Metall ic as well as gaseous impurities have been 
A p o r t i o n  of t h i s  period has  been used t o  attempt t o  c o r r e l a t e  
hydrogen content as measured by h o t  extraction w i t h  OH content measured 
mass spectrographically.  This i s  a d i f f i c u l t  problem, due i n  par t  t o  the 
nature of the mater ia l ,  and a l so  t h e  common occurrence of water vapor as a 
residual gas i n  the vacuum system of the spectrograph. 
As a fur ther  check on mass-spectrographic analyses, a s e r i e s  of 
wet and colorimetric chemical methods a r e  being investigated.  
sodium, potassium, calcium, f luorine,  and s i l i c o n ,  are  being determined by 
these methods because emission-spectrographic analyses are  somewhat doubt -  
f u l  i n  these cases.  
The elements, 
Detai ls  of  these investigations a re  given i n  the following sec- 
t i o n s .  
11. A C T I V I T Y  DURING THE REPORTING PERIOD 
A .  MqO Analyses. 
A s e r i e s  of seven WgO samples selected from various points i n  the 
JPL process f o r  preparation of pure MgO from magnesium metal has been 
analyzed mass spectrographically.  These materials were e i t h e r  powders or 
compacts. 
The powdered m a t e r i a l s  were mixed w i t h  p u r e  s i l v e r  powder (two 
p a r t s  by we igh t  s i l v e r  t o  one p a r t  by we igh t  MgO), p r e s s e d  i n t o  a p p r o p r i a t e  
shape ,  and r u n  i n  t h e  mass spec t rog raph .  T h i s  h a s  proven t o  be a r e l i a b l e  
and a c c u r a t e  p rocedure .  The major  problems w i t h  t h i s  t y p e  of a n a l y s i s  are 
poor mix ing ,  which results i n  an inhomogeneous e l e c t r o d e ,  and contamina- 
t i o n  from the d i e .  We have been a b l e  t o  avo id  both o f  these problems by 
u s i n g  an extended mixing time and e x t e n s i v e  removal of  t h e  s u r f a c e  of  t h e  
e l e c t r o d e  p r i o r  t o  a n a l y s i s .  
The compacted samples have been ana lyzed  by a new t e c h n i q u e  
w h i c h  c i r cumven t s  the use of  a conduct ing a d d i t i v e .  
d i r e c t  s p a r k i n g  o f  two MgO e l e c t r o d e s  a t  h i g h  (50-60 kV) s p a r k  v o l t a g e s .  
The advan tages  of the  method a r e  obvious:  there i s  no con tamina t ion  from 
c r u s h i n g  o r  h a n d l i n g  t h e  sample; and t h e  s e n s i t i v i t y  and accu racy  a r e  a t  
l eas t  as good as t h o s e  of  t h e  s i l v e r  powder method. A t y p i c a l  mass spectrum 
of an MgO material i s  shown i n  F i g .  1. 
Th i s  method i n v o l v e s  
One d i s a d v a n t a g e  i s  t h e  enhancement o f  t he rma l  i o n i z a t i o n .  During 
the s p a r k i n g  of two MgO e l e c t r o d e s ,  enough h e a t  i s  g e n e r a t e d  t o  c a u s e  t h e  
e l e c t r o d e s  t o  glow. 
as sodium and po ta s s ium,  and would lead t o  e r r o n e o u s l y  high resu l t s .  
e v e r ,  the use of  t h e  doubly i o n i z e d  l i n e ,  Na o r  K , a t  masses 11.5 and 
19.5, w i l l  g i v e  a t r u e  i n d i c a t i o n  o f  the c o n c e n t r a t i o n  o f  t h e  element. 
r e s u l t s  of these a n a l y s e s  a r e  shown i n  Tab le  1, on t h e  f o l l o w i n g  page. 
T h i s  i s  more than enough heat  t o  i o n i z e  e l emen t s  such 
How- 
++ tl- 
The 
Emiss ion - spec t rog raph ic  ana lyses  a s  a check on t h e  mass s p e c t r o g r a p h  
have a l s o  been performed f o r  t h o s e  elements w h i c h  can be handled by emiss ion  
t e c h n i q u e s .  The emiss ion  method invo lves  t h e  u s e  of a ser ies  of c a r e f u l l y  
p r e p a r e d  s t a n d a r d s  which a r e  of known i m p u r i t y  c o n t e n t ,  The spectrum of 
- 2 -  
: *  . 
. . .n . .. 
FIG. 1 Mass spectrum produced from two MgO electrodes. Spark voltage 
5.5 kV. The high aluminum content is from aluminum holders. 
c 
4 
t h e  unknown i s  compared t o  these s t a n d a r d s  and t h i s  h a s  r e s u l t e d  i n  
r e a s o n a b l e  comparisons between mass and emis s ion  v a l u e s .  Tab le  2 l i s t s  
the  resu l t s  of  e m i s s i o n - s p e c t r o g r a p h i c  a n a l y s e s .  
T a b l e  1. Mass-spectrographic  a n a l y s e s  of  JPL MgO (ppma). 
10 -5 - 4 Sample No: - 2 3  - 
Boron 
Ni t rogen  
F l u o r i n e  
A 1  umi num 
Sodium 
S i l i c o n  
Calcium 
C h l o r i n e  
I r o n  
3 1  5 5 
195 240 170 95 
17 200+ 125  250+ 
- - 30 
< 1  1 1 < 1  
190 175 115 170 
1 2  75 60 30 
65 125 110 95 
8 3 20 8 
3 
110 
250+ 
15 
< 1  
75 
4 0  
4 5  
20 
11 -
8 
210 
30 
5 
< 1  
65 
30 
35 
14  
13 
< 1  
200 
50 
30 
< 1  
80 
30 
55 
10 
-
T a b l e  2. Emiss ion - spec t rog raph ic  a n a l y s e s  of JPL MgO (ppma). 
13 -11 -10 -5 - 4 - 3 - 2 Sample No, - 
Boron 1 1 1 1 1 3 1 
A 1  um i num 3 7 15 30 20 5 5 
S i l i c o n  30 10 20 7 15 30 30 
Ca 1 c ium 5 10 15 5 10 25 15 
I r o n  2 2 2 2 2 7 5 
The most obvious p i e c e  of  i n f o r m a t i o n  t o  be d e r i v e d  from these 
a n a l y s e s  conce rns  the ' ITA e x t r a c t i o n  of t h e  magnesium n i t r a t e  s o l u t i o n .  
The h i g h  p u r i t y  o f  t h e  magnesium s t a r t i n g  material and the lesser p u r i t y  
of the samples numbered 3 ,  4 ,  5, and 1 0 ,  i n d i c a t e  t h a t  the TTA e x t r a c t i o n  
i s  n o t  on ly  ha rmfu l ,  b u t  unnecessa ry .  Contaminat ion of  h i g h  p u r i t y  mate- 
r i a l s  w i t h  r e a g e n t s  i s  not  unusual  and t h i s  i s  a p p a r e n t l y  t h e  c a s e  w i t h  
t h e  e x t r a c t i o n  s t e p .  
- 3 -  
5 
The determination of H and OH i n  these samples i s  proving 
a d i f f i c u l t  problem, The presence of water vapor as one of the res  
gases i n  the vacuum system i s  the most l i k e l y  cause of t h i s  t rouble  
t o  be 
dual 
A s e r i e s  of four samples of known OH content (GP 125, OP 128, 
O? 111, OP 1 4 )  has been analyzed mass spectrographically i n  an attempt t o  
use the OH peak a t  mass 17 as an indication of the hydrogen content. 
These experiments have been unsuccessful. 
over a f a c t o r  of t h i r t y ,  even on successive runs on the same sample. 
Continual baking of the source seems t o  have no e f f e c t  on t h e  peak. 
i s  becoming apparent tha t  we have a water adsorption problem which nay 
The peak a t  xass 17 changes 
I t  
best be solved w i t h  the aid of a l iquid nitrogen cooled t r a p  inside the 
source. This type of t r a p  has been reported i n  the l i t e r a t u r e  t o  lead t o  
grea te r  reproducibi l i ty  for  the analysis of v o l a t i l e s .  
As an indication of the v a r i a b i l i t y  we have been seeing, Table 3 
shows t h e  r e l a t i v e  heights of t h e  mass 17 peak during f i v e  successive r u n s  
on the  same sample. The sample was baked between runs and the source 
pressure was 5 x 10 t o r r .  -8 
Table 3.  Relative height o f  mass 17 peak for  OP 128, 
P i a t e  N o .  PPU (atemic) 
404 1 GOO 
405 50 
40 6 300 
407 50 
408 100 
We plan t o  i n s t a l l  a source cold t r a p  i n  the  near future  and re- 
r u n  these samples, 
- 4 -  
The d e t e r m i n a t i o n  of hydrogen by h o t  e x t r a c t i o n  h a s  n o t  proved 
t o  be as a c c u r a t e  as t h i s  technique can be f o r  m e t a l l i c  systems.  
samples ,  OP 125,  OP 128,  OP 111,  and OP 1 4 ,  have been r u n  u s i n g  h o t  extrac- 
t i o n ,  b u t  once a g a i n  there has  been a l a r g e  v a r i a t i o n  i n  s u c c e s s i v e  r u n s .  
The r e p r o d u c i b i l i t y  of  h o t  e x t r a c t i o n  f o r  hydrogen i n  m e t a l s  i s  f 20% a t  
w o r s t .  
the same sample.  
i s  as f o l l o w s :  OP 125 > OP 128 > OP 14 = OP 111. F u r t h e r  work w i l l  be 
done here .  
The f o u r  
We have found v a r i a t i o n s  much l a r g e r  t h a n  t h i s  f o r  r e p e a t  r u n s  on 
A r e l a t i v e  r a n k i n g  of t h e  f o u r  samples has  been made and 
The use of t he  mass s p e c t r o g r a p h  f o r  hydrogen a n a l y s e s  i s  now 
be ing  i n v e s t i g a t e d .  Our f i r s t  checks of  t h e  i n s t r u m e n t  b l ank  l e v e l  f o r  
hydrogen ind ica t ed  ex t r eme ly  high v a l u e s  (600 ppma). 
S a n d i a  C o r p o r a t i o n ,  however, i n d i c a t e d  t h a t  i t  has  been p o s s i b l e  t o  a n a l y z e  
hydrogen a t  much lower l e v e l s  - i n  f a c t ,  as low a s  1-10 ppm a tomic .  We 
have made a n o t h e r  check on ou r  in s t rumen t  w i t h  mater ia ls  used i n  t h e  
S a n d i a  i n v e s t i g a t i o n  and f i n d  t h a t  i t  may be p o s s i b l e  f o r  u s  t o  do hydro- 
gen a t  these low l e v e l s .  
( w e i g h t )  hydrogen has  been ana lyzed  with excellent resul ts  (1,8 ppm we igh t  
by our  i n s t r u m e n t ) .  
Some recent work a t  
A s t a n d a r d  molybdenum a l l o y  c o n t a i n i n g  1.0 ppm 
We p l a n  t o  i n v e s t i g a t e  t h i s  t e c h n i q u e .  
A pape r  d e s c r i b i n g  o u r  t e c h n i q u e  f o r  t h e  mass - spec t rog raph ic  
d e t e r m i n a t i o n  of  i n t e r s t i t i a l  elements h a s  been w r i t t e n ,  approved by JPL,  
and w i l l  be submi t t ed  t o  A n a l y t i c a l  Chemis t ry .  
B. A n a l y s i s  of  Tantalum Carbide.  
A ser ies  of e igh t  t a n t a l u m  c a r b i d e  specimens i s  b e i n g  ana lyzed  
Since the m a t e r i a l s  are  powders 
Results on t h e  
f o r  oxygen u s i n g  the mass s p e c t r o g r a p h .  
t h e y  are  b e i n g  mixed w i t h  pure s i l v e r  p r i o r  t o  a n a l y s i s ,  
- 5 -  
f i r s t  f i v e  samples a r e  a v a i l a b l e ,  The v a l u e s  a r e  l i s t e d  i n  T a b l e  4 ,  
T a b l e  4 .  Oxygen c o n t e n t  of  CIBA TaC. 
Sample No, 
3 - 2  
3 - 1  
2 - 5  
2 - 3  
2 - 2  
Oxygen ( w t .  %) 
.060 
.053 
.060 
0 28 
022 
These v a l u e s  do  no t  a g r e e  w i t h  vendor a n a l y s e s ,  b u t  we w i l l  w a i t  u n t i l  
the l a s t  three samples a r e  done be fo re  a t t e m p t i n g  any a n a l y s i s  of  t he  
d a t a  
C ,  Wet Metnoas 101 Stiectc: :=puri t ies .  
As a f u r t h e r  check on t h e  accuracy of  the mass s p e c t r o g r a p h ,  we 
are c u r r e n t l y  u s i n g  wet chemical methods t o  de t e rmine  t h e  c o n c e n t r a t i o n  
of s u c h  elements as sodium, potassium, ca l c ium,  f l u o r i n e ,  and s i l i c o n .  
Sodium, po ta s s ium,  and calcium w i l l  be ana lyzed  by f lame pho tomet r i c  t ech -  
n i q u e s .  
l e v e l s  of  these elements i n  MgO and the accuracy  i s  a l s o  good. Th i s  equip-  
m e n t  w i l l  be a v a i l a b l e  a t  the Research Center ear iy  next year. 
The s e n s i t i v i t y  of t h i s  method i s  more t h a n  adequa te  f o r  t h e  
F l u o r i n e  w i l l  be ana lyzed  by a p o l a r o g r a p h i c  p rocedure .  The 
s e n s i t i v i t y  and accu racy  o f  t h e  method are adequa te .  
a n a l y z e d  c o l o r i m e t r i c a l l y  by t he  molybdate method. 
S i l i c o n  w i l l  be  
D .  L a s e r  S o u r c e .  
We have made two t r i p s  i n  t h e  p a s t  month t o  l a b o r a t o r i e s  which 
have e x p e r i e n c e  w i t h  l a s e r  s o u r c e s  i n  t he  mass s p e c t r o g r a p h  (RCA and G . E . ) .  
Both l a b o r a t o r i e s  f e e l  t ha t  there i s  need f o r  improvement b e f o r e  t h e  l a s e r  
- 6 -  
1 ,  ' I  I -  
I '  
a 
I 
becomes a useful t o o l  f o r  t h e  l o c a t i o n  of i m p u r i t i e s .  
method has been no ted  f o r  t h i s  type  of  a n a l y s i s .  
p o i n t e d  e l e c t r o d e  as a probe has  found some a p p l i c a t i o n  f o r  i m p u r i t y  
l o c a t i o n .  T h i s  work h a s  been done a t  General  Telephone L a b o r a t o r i e s  and 
shows p a r t - p e r - m i l l i o n  s e n s i t i v i t y  i n  a r e a s  less t h a n  10 mils s q u a r e .  
Another  useful 
The use o f  a f i n e l y  
The most common problem w i t h  the l a s e r  s o u r c e  has been v a r i a -  
S u c c e s s i v e  laser p u l s e s  i n  t i o n  i n  t h e  amount o f  i o n  cur ren t  produced. 
t h e  same s p o t  produce i o n  c u r r e n t s  which v a r y  by a f a c t o r  of  one hundred. 
111. PLANS FOR NEXT QUARTER 
During t h e  next q u a r t e r  we s h a l l  a t t e m p t  t o  d e v e l o p  a s u i t a b l e  
method f o r  hydrogen and hydrox ide .  
easiest  t o o l  i f  r e a s o n a b l e  c o r r e l a t i o n s  can be maae. 
The mass s p e c t r o g r a p h  would be t h e  
Wet a n a l y s e s  of f l u o r i n e  and s i l i c o n  i n  JPL MgO m a t e r i a l s  w i l l  
be performed by methods o u t l i n e d  i n  Sec,  11. We w i l l  a l s o  a t t e m p t  t o  
c o r r e l a t e  tantalum-carbon r a t i o s  w i t h  oxygen c o n t e n t  i n  t a n t a l u m  carb ide  
specimens.  
I V ,  OTHER ACTIVITIES 
We have p a r t i c i p a t e d  i n  a round-robin f o r  the analysis of  i n t e r -  
s t i t i a l s  i n  r e f r a c t o r y  metals sponsored by the N a t i o n a l  Academy of  S c i e n c e ,  
Most of the l a b o r a t o r i e s  used s t a n d a r d  methods,  b u t  ou r  v a l u e s  were i n  good 
agreement  a s  shown. 
- 7 -  
Y 
i 
I .  
0 8  * . <’ 
I Molybdenum 
Carbon 
Nitrogen 
Oxygen 
I Tantalum 
Carbon 
Nitrogen 
Oxygen 
I Tungsten 
Carbon 
Nitrogen 
Oxygen 
Niobium 
Carbon 
Nitrogen 
Oxygen 
- M.S. True Value ppm wt. 
215 230 
7 16 
33 7 
20 
7 
16 
27 
11 
6 
28 
12 
34 
17  
18 
14 
9 
6 
7 
10 
43 
68 
- 8 -  


Development of chemical analysis techniques for advanced materials research program Fourth quarterly progress report, Sep. 1 - Nov. 30, 1965

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