Adaptation of commercial instrument which measures nitrogen and oxygen in steel gave results in less than four minutes. Sample is heated in helium atmosphere in single-use graphite crucible. Platinum flux facilitates melting of sample. Released gases are separated chromatographically and measured in thermal-conductivity cell

Davis, W. F.

Graab, J. W.

Merkle, E. J.

English

NASA Technical Reports Server

September 1974	 B74-10085 
NASA TECH BRIEF 
Lewis Research Center 
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. 
Rapid Method for Determining 
Nitrogen in Tantalum and Niobium Alloys 
. 
S
A commercially available instrument developed for the 
analysis of gases in steel has been adapted to rapidly 
determine the nitrogen content in tantalum and niobium 
alloys. The conventional method for determining nitrogen 
content, a modified Kjeldahl procedure, requires four to 
six hours; this new method requires less than four 
minutes. 
Refractory alloys are promising candidates for skin 
materials for the Space Shuttle. Nitrogen and other 
interstitial -elements are critical to the strength and 
corrosion resistance of refractory metals at high tempera-
tures. Thus, it is important to determine nitrogen content, 
and to monitor changes in nitrogen content, in these 
alloys below the 100 parts-per-million level. The method 
most often used is a modified Kjeldahl procedure con-
sisting of chemical dissolution, distillation and spectro-
photometric measurement which takes four to six hours 
to complete. Investigation of an inert gas fusion procedure 
resulted in the adaptation of a commercial instrument, 
developed to measure nitrogen and oxygen in steel, which 
gave comparable results in less than four minutes. 
In this inert gas fusion procedure, the sample is heated 
to approximately 2973 K (4892°F) in a helium atmos-
phere in a single-use graphite crucible. A platinum flux is 
used to facilitate melting of the sample. The released gases 
are separated chromatographically and measured in a 
thermal-conductivity cell. 
A comparison of nitrogen values by the inert gas fusion 
method and a modified Kjeldahl procedure has been made 
for two tantalum-base alloys and six niobium-base alloys. 
The designation and nominal composition of the alloys 
tested are: T-lll (Ta-8W- 2H0, T-222 (Ta-I0W-2.51 ­10, 
B-66 (Nb-5Mo-5V-lZr), Cb .752 (Nb-9.8W-2.7Zr), Nb-iZr, 
C-1 29Y (Nb-10W-l0Hf-0.IY), WC-3015 
(Nb-29Hf- 15W-i Zr-4Ta), and FS-85 (Nb-28Ta- low-I Zr). 
The inert gas fusion method results are comparable to 
the modified Kjeldahl results. For the tantalum and 
niobium alloys tested, the standard deviation for the inert 
gas fusion method was 5 to 7 percent.
Advantages of the inert gas fusion method are: 
1. Both oxygen and nitrogen are determined on the 
same sample specimen; 
2. The elimination of the time consuming Kjeldahl 
dissolution, distillation, and spectrophotometric measure-
ment steps; and 
3. Reduction of interference by nitrogen compounds 
normally present in the laboratory atmosphere. 
Notes: 
1. Further information is available in the following 
report: 
NASA TM-X-3067 (N74-26032), Comparison of 
Inert Gas Fusion and Modified Kjeidahl Techniques 
for the Determination of Nitrogen in Niobium 
Alloys 
Copies may be obtained at cost from: 
Aerospace Research Applications Center 
Indiana University 
400 East Seventh Street 
Bloomington, Indiana 47401 
Telephone: 812-337-7833 
Reference: B74-10085 
2. Specific technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B74-10085 
Patent Status: 
NASA has decided not to apply for a patent. 
Source: E.J. Merkle, J.W.Gaab,

and W.F. Davis

Lewis Research Center

(LEW-12237) 
Category 04 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the Aeronautics and S pace Administration. Neither the United Slates
	 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=19740000085 2020-03-17T14:05:49+00:00Z


Rapid method for determining nitrogen in tantalum and niobium alloys

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server