Neutron activation analysis techniques were employed for the study of the wear and performance characteristics of slip ring and rotor assemblies and of the problems arising from environmental conditions with special reference to surface contamination. Results showed that the techniques could be successfully applied to measurement of wear parameters

Furr, A. K.

English

NASA Technical Reports Server

November 1967
	 Brief 67-10403 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Wear Studies Made of Slip Rings and Gas Bearing Components 
The wear and performance characteristics of slip 
ring and rotor assemblies were investigated by means 
of neutron activation analysis techniques. The same 
techniques were also used to investigate some of the 
problems arising from environmental conditions with 
special reference to surface contamination. 
The neutron activation analysis technique was 
particularly suitable for study of the wear charac-
teristics of the slip ring assemblies since gold consti-
tutes one of the major surface structural materials and 
is highly sensitive to neutron activation. Studies were 
made of the rate of wear of slip rings as a function of 
running time for characteristic brush contact forces 
and rotor speeds. Consistent results were obtained 
which indicated that the approach was satisfactory. 
Thermal neutron activation analysis techniques are 
normally not applied to materials where the elements 
involved do not activate readily, such as carbon, 
hydrogen, oxygen, and other elements represented in 
organic compounds. However, sample activations of 
some of the materials involved in the structural com-
ponents showed that they contained, in addition to the 
organic compounds, sufficient amounts of easily acti-
vatable trace elements to make it reasonable to at-
tempt to try and isolate these elements in the surface 
contaminant. 
Two approaches were made to the problem of iden-
tification of the nature of the surface contaminant.
One procedure consisted of collecting and activating 
samples of the surface contaminant and then compar-
ing the results obtained to the results expected from 
nearby structural components. 
The second approach investigated step by step the 
factors that went into the manufacture and prepara-
tion of the assemblies to determine which process was 
responsible for the residue. It was found that small but 
significant amounts of residue were being left behind 
during the cleaning of the assemblies. 
The investigations showed that neutron activation 
analysis techniques could be successfully applied to 
measurement of wear parameters for the specific as-
semblies of interest. 
Note: 
Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10403 
Patent status: 
No patent action is contemplated by NASA. 
Source: A. Keith Furr 
of Virginia Polytechnic Institute 
under contract to 
Marshall Space Flight Center 
(M FS- 12882) 
Category 05 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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Wear studies made of slip rings and gas bearing components

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