An evaluation is presented of silicon carbide, zirconium diboride, and iridium-coated graphite as materials for construction of furnace cores which could operate under highly oxidizing conditions at temperatures of approximately 2,200 C in the presence of molten aluminum oxide. It was found that silicon carbide and zirconium diboride could not withstand oxidizing atmospheres in the presence of aluminum oxide at temperature 2,200 C. However, graphite furnace cores coated with iridium were found to be useful furnace cores at 2,200 C in an oxidizing atmosphere for reasonably extended periods of time

Duhamel, A. P.

English

NASA Technical Reports Server

I I .  I THE DEVELOPMENT OF MATERIALS CAPABLE 
. OF OPERATION IN A N  OXlDlZfNG ATMOSPHERE 
FOR EXTENDED PERIODS OF TIME 
I 
\ 
A. P. DUHAMEL 
. ' COMMONWEALTH SCIENT,IFIC CORPORATION 
6 .  
, 500 PENDLFTON STREET 
. . * A  , . ALEYANDRIA, VIRGINLA 22314 
I 
I , . (NASA-CR- 122425) THE DEV3LOPHENT OF N72-25551 
I ?¶ATERIALS C A P A B L E  OF OPESATIOl i  IN AN b ,  ' O X I D I Z I N G  ATYOSPY.IE3E FOR EXTENDED P E R I O D S  
1 OF TIRE Final A . P .  9 u h a r v l  (Commonwealth U n c l a s  
i 1 S c i e n t i f i c  Carp, f mag 1972  6 p CSCL 1 ID G 3 / 1 8  3C.741 " :!'. ' I I '. . . , . 
I ) . t  . ! . .  
, I  . '  MAY 1972 
. . 
;, . 
I ,  8 . 1  * . '  
. . 
( .  
. . 
, . 
- 1 
, #  < 
.a .I' 
. 1 .  . ' . ; ) .  FINAL REPORT FEB. 1$2! - MAY 1972 ;. i 
!, . r 
. , 
0 .  
, , . 
. : ,  
# 
. . 
' S  
, .  PREPARED FOR , 
. . 
, - 4 t ! . * . ,  GODDARD SPACE FLIGHT CENTER 6 I , . I  a GREENBELT, MARYLAND 20771 i a  , . * . .. 
I' . .  . 1 .  , I . .. 
' .  . 
. I 1 
- 
, ' .. L .  
I 8 I ' ,, ' ., 
4 ,  ' 0 ,  . . '  . , 
:. 0 ' , , i . , ! .  
. . * .  , '  
4 '. 4 ,. ' 
, . 
. 9 
3 .  
' I 
* ,  
- 
. . 
C~MMONWEALTH 
https://ntrs.nasa.gov/search.jsp?R=19720017901 2020-03-11T18:09:33+00:00Z
The Development of Materials Capable of 
' 
May 1972 I 
izing Atmosphere for p p r g i p  i n . 3  Oripme 6. perform in^ Or~onixotion Code ten e Per1 s o 
7. Author(s) 
TECHNICAL REPORT STANDARD TITLE PAGE 
I None , ! 
3. Recipient's Catolog No. 1. Report No. 
Final Report 
A. P. Duhamel 
9. Performing Organization Name and Address 
Commonwealth Scientific Corporation 
500 Pendleton Street 
Alexandria, Virginia 22314 
12. Sponsoring Agency Nomr ond Address 
Gddard Space F l  ight Center 
Greenbelt, Maryland 20771 
Mr. John deluca (Building 12) 
I 
16. A b s h c t  
The work performed under this program has been involved with 
an evaluation of silicon carbide, zirconium diboride, and iridium coated 
graphite as materials for construction of furnace cores which could operate 
I 
under liigl-ily oxidi+Ii;g ccfiditic,?; =t temperatures of approximately 2,200 C 
in the presence of molten aluminum oxiaa. It was found that silicon 
O I 
carbide and zirconium dibaide could not withstand oxidizin atmospheres 
I 
8 in the presence of aluminum oxide at temperatures of 2,200 C. However, 
graphite furnace cores coated with iridium were found to be useful 
furnace sores at 2,200'~ in on oxidizing atmosphere for reasonably 
1 extended periods of time. 1 
4. Ti t le ond Subtitle 1 5. Report Date 1 I 
2. Government Accession No. 
18. Worr Unit plo. 
- 
11. Controct or Grant NO. 
NASS-21390 
13. Type of Report and Period Covered 
Final Report 
Feb. 1971-May 1972 
1 4 .  Sponsoring Agency Code 
17. Key Words (S tectod by Amhor(m) 18. Oirtribution Statement 
I S .  Supplementury Notes ' 
Materials 
I 
I Furnaces 
I .. ' - 
22. Price4 
b L 
21. Ne. of Pa@es 
. 
19. k r r i t y  Classif. (mf thi@ toport) 
51 one 
20. k c u r i t y  Clossif. (of th i r  page) 
None 
PREFACE 
The objective of the work presented in this report was to 
investigate materials capable of operation for extended periods of time 
in on oxidizing atmosphere at 200'~ in the presence of molten 
aluminum oxide. The materials to be investigated were s i l  icon carb ide 
and zirconium diboride along with any other materials which might 
be useful for the production of furnace cores which could be utilized 
under the conditions mentioned above. Since silicon carbide and 
zirconium diboride proved to be ineffective materials in an oxidizing 
atmosphere at 2 , 2 0 0 ~ ~  it was decided to investigate high density graphite 
' coated with iridium. it was found that this technique yielded furnace 
corer which could be ruccessfull y util ired at temperatures of 2,200'~ 
and an oxidizing atmosphere. The primary conclusions reached from this 
work are that silicon carbide and zirco~.rium dibor:de cannot be used 
0 
under highly oxidizing conditions at temperatures reaching 2,200 C. 
However, i t  would be recommended thak furnace cores coated with 
iridium be utilized for such applicr:ilr?:. 
' I 0 INTRODUCTION 
This report i s  the final report on Contract NAS5-21390. 
The report i s  concerned primarily with the results of the experimental 
work performed with silicon carbide, zirconium diboride and high ' 
density graphite coated with i r id i~m.  The objective of the program 
was to evaluate these materials for their potentibl to produce furnace 
cores which could operate for extended periods of time at 2 , 2 0 0 ~ ~  in 
an oxidizing . mosphere in  the presence of molten aluminum axide. 
2,O EXPERIMENTAL AND RESULTS 
Considerable experimental 'work was performed with high 
density silicon carbide and zirconium diboride before ~t ten- ion was 
directed to the investigution of high density graphite c w t r d  with 
. . 
~r~dium. , However, since the level of effort available for this program 
was relatively low, experimental effort on the investigation of each 
material had to  be severely restricted in  order to  achieve the overall 
goals of the program. 
Silicon carbide furnace cores were prepared by hot pressing 
s i l  icon carbide to  a very high density impervious material . The tubes 
., >.,,.. . ..,.w ere submitted to. t h e  Goddard Space Flight Center f ~ r  evaluation at 
, a '  , ., , :;;;;;: .. $ ' .  . '  . . , 
' A . 1. 
. . 
"2, XK)"C in an oxidizing atmosphere. It was found that the' silicon 
. . 
... carbide furnace cwes prepared under optimum hot pressing conditions 
I ! . 
. 
* were stii l r i lat ively ieactive in an oxidizing atmosphere. Chemical 
. analysis of the products of reaction of oxygen with the silicon carbide 
& 
corer indicated: thht the silicon carbide was reacting rapidly at 2,200'~ 
! 
. 
. . 
, . to yicild si lkon dioxide; From this *data it beeame o l w  . 
' * .  I .. @ c ' *  
, . 5 
a that silicon carbide 'would not be a useful material for further investigation 
* 
.. 4 under the temperature and oxidizing ' conditions selected. Further 
/7:I_A3 
attempt at producing furnace cores from silicon carbide were therefore Ll 
discontinued . . 
COMMONWEALTHSCIEM~~IFIC CORPORATION- - 
Thd experimental work with zirconium diboride led to 
essentially the same results as the work with silicon carbide, i .e., 
oxidat ion to  zirconium oxide. Since the initial zirconium diboride 
powder was difficult to obtain in a pure form it i s  possible that 
these impurities were adversely effecting the hot pressing technique 
although it i s  feit that under the temperatures and oxidizing conditions 
utilized during this investigation zirconium diboride would not be 
a useful furnace core material. 
The experimental work with graphite coated with iridium 
proved to be more successful for the preparation of furnace cores. 
In this case a high density graphite &as machined t o  the appropriate 
dimensions. The purpose of the graphite was simply to serve as a 
support for two iridium sleeves. Two iridium sleeves were prepared, 
* 
one for the inner side of the graphite tube and one for the outer 
side of the graphite tube. The iridium sleeves were prepared by 
welding sheets of iridium metal tc the appropriate dimensions. The 
graphite tube was then placed between the inner and outer sleeve 
t o  construct the furnace core. This technique produced furnace cores 
which were able to  withstand the high temperatures and highly oxidizing 
conditions under which they were exposed. The furnace cores have 
been delivered to the Goddard Space Flight Center and are n ' w  in  use. 
3.0 ' NEW TECHNOLOGY 
I 
As indicated in the report submitted under separate cover 
to the New Technology Division of the Goddard Space Flight Center 
* 
d .  it is  not cmidered that any new technqlogy wa; under t h i s .  , ' 
1) It i s  concluded that furnace cores which can 
0 
withrtond temperatures of 2,200 C in  an oxidizing atmosphere 
q cannot be constructed from s i l  icon carbide. 
2) It is  concluded that furnace cores which can 
withstand temperatures of 2 , 2 0 0 ~ ~  in  on oxidizing atmosphere 
cannot be constructed from zirconium diboride. 
3) It i s  concluded that furnace cores which can 
0 
withstand oxidizing conditions at temperatures of 2,XO C can 
be constructed from graphite coated with iridium. 
5.0 RECOMMENDAT IONS 
The principal recomnlendations which can be made 
. 
at this time would be to  investigate better and cheaper methods 
of preparing furnace cores from graphite coated with iridium. 
While the cost of iridium is  high, it should be noted that since 
iridium is  a precious metal it may be returned to  the manufacturer 
after we and approximately 85% of i t s  original c a t  i s  returned 


The development of materials capable of operation in an oxidizing atmosphere for extended periods of time

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server