Wrapped molybdenum foil with silica fabric insulation and wrapped tantalum foil with carbon fabric insulation are usable to 1367 K and up to 2478 K, respectively, both offer marked space saving and efficiency in high temperature operations. Graph displays temperature profiles at end of firing period

Carlson, L. W.

English

NASA Technical Reports Server

August 1971	 Brief 71-10289 
NASA TECH BRIEF 
NASA Pasadena Office
	
A 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield; Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology, Utilization Office, NASA, Code KT, Washington, D.C. 20546.
Improved Insulating Materials Effective at Extremely 
High Temperatures 
Two multilayer foil and fabric insulators,
	 usable	 tests, the foil and fabric were wrapped to a radial 
to	 1367 K (2000° F) and up to 2478 K (4000° F),
	 thickness of 1.47 cm (0.58 in.) around the combus-
respectively, offer marked space saving and efficiency
	 tion	 chamber	 of	 a	 graphite	 rocket engine. The 
3400 
2000 Wrapped Tantalum Foil and 3200 
Carbon Fabric Insulation, 3000 2478 K (4000° F) 
Theoretical Combustion 2800 Temperature
2600 
2400 
1500
2200 LL 
2000 ,-
1800 
0. 
E 1600
W 
0. 
E 
Wrapped Molybdenum Foil 
1000
and Silica Fabric Insulation, 1400 
1367 K (2000° F) 
Theoretical Combustion 1200 Temperature
— 1000 
500 1 200
I	 I	 10 
0	 2	 4	 6	 8	 10	 12	 14	 16	 18	 20 21 
Wrap Number 
Typical Temperature Profiles at End of Firing Period 
in nuclear power, plasmas, magneto hydrodynamics,
	 assembly was installed in a vacuum chamber which 
and other high-temperature operations.
	 was taken down to an initial vacuum of 1.3 x 10-2 
The lower-temperature configuration consists
	
N/rn 2
 (10 4 torr). The engine was fired at a 
of molybdenum foil, 0.0254 mm (0.001 in.) thick,
	 theoretical combustion temperature of 1367 K 
wrapped with an interleaved layer of silica cloth
	 for a period of 1000 sec. A maximum heat load 
around the object to be insulated. In developmental
	 of 46 W of thermal energy was detected by the 
Agolk	 (continued overleaf) 
	
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
	
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
	
Government nor any person acting on behalf of the United States
	 will be free from privately owned.rights. 
https://ntrs.nasa.gov/search.jsp?R=19710000288 2020-03-17T02:20:32+00:00Z
calorimeter which surrounded the insulation. Typical 
temperatures at various points in the wrapped in-
sulation, as indicated at the end of the firing period, 
are shown in the figure. 
The foil maintained its integrity during firing, 
although the surface near the combustion chamber 
was rough and discolored. The silica fabric was 
only slightly sintered in the layers closest to the 
chamber. The low effective thermal conductivity 
of this molybdenum-silica insulator at relatively 
low temperatures favors its use up to 1367 K. 
A similar configuration of tantalum foil, 
0.0254 mm thick, and carbon cloth is usable at 
even higher temperatures. During testing, the tantalum-
carbon insulation materials were wrapped to a radial 
thickness of 2.54 cm (1.0 in.) around the combustion 
chamber. Despite an initial vacuum similar to that 
obtained in the molybdenum-silica tests, the pres-
sure rose to between 2.66 >< 102 to 1.64 x 103N/m2 
due to extreme out-gassing during firing at a theo-
retical temperature of 2478 K. The maximum heat 
load was 113 W of thermal energy. Typical tempera-
tures at the end of the firing period, as detected at 
various levels within the tantalum-carbon insulation 
package, are also shown in the figure. 
The inner layers of tantalum foil combined 
chemically with the carbon cloth during firing, 
forming brittle tantalum carbide. This carbide, 
however, is itself an effective part of the insulator 
because of its reflective surface. The strength of the 
carbon cloth was not significantly affected, although
the cloth was somewhat changed in appearance in 
the hotter regions. The tantalum-carbon insulation 
essentially retained its integrity throughout the 
firing and soakback period. 
Above 1367 K, the effective thermal conductivity 
of the tantalum-carbon insulator is lower than that 
of the molybdenum-silica one. The tantalum-carbon 
insulator is therefore recommended for use at tem-
peratures above 1367 K up to 2478 K. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP7 1-10289 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to: 
Patent Counsel 
Mail Code 1 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Source: L. W. Carlson of

North American Rockwell Corp.

under contract to

NASA Pasadena Office

(N P0-12067) 
Brief 71-10289	 Category 04


Improved insulating materials effective at extremely high temperatures

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