Measuring and correlating the thermal conductivity and ultrasonic transmission of seven hot-brazed-bonded copper plates established a relationship between heat transfer and ultrasonic transmission properties of the bonds. This relationship permits the prediction of heat transfer characteristics from ultrasonic transmission tests

Di~novi, R. A.

English

NASA Technical Reports Server

March 1967 Brief 67-10037 
AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Correlation Established Between Heat Transfer and Ultrasonic Transmission

Properties of Copper Braze Bonds 
U 
C 
0 
an 
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:	 0.8 
. E 
In
0.2 
z<
0.2 0.4 0.6 0.8 1.0 
NK = K/Kstd, normalized thermal conductivity in 1mm 2
 areas 
Normalized ultrasonic transmission at 1.0 Mc in 1 mm2 
areas versus normalized thermal conductivity in 1 mm2 
areas for copper braze bonds (f= 1.0 Mc) 
The solution: 
A relationship was experimentally established be- 
heat transfer and ultrasonic transmission of brazed 
bonds by measuring and correlating the thermal con- 
ductivity and the ultrasonic transmission of seven hot- 
brazed-bonded copper plates. A typical correlation is 
shown. The amplitude of the transmitted ultra- 
sonic pulse decreases with a decrease in heat 
transfer, and thus with bond quality. The fact that 
this correlation is established for copper braze bonds 
indicates that similar knowledge can be obtained for 
other types of bonds, e.g., the diffusion bonds of reac- 
tor fuel elements. For any type of bonded elements, 
this method will yield a definitive relationship per- 
mitting the prediction of heat transfer characteristics 
from the ultrasonic transmission properties. This 
relationship can then be used as the basis for setting 
The problem: 
To determine whether a correlation exists between 
heat transfer and ultrasonic transmission through 
copper braze bonds. The integrity of the bond between 
the fuel and the cladding of nuclear fuel elements is 
of prime importance. Heat from the fuel must flow 
across the bond to react with the coolant. Therefore 
the bond must be capable of providing adequate heat 
transfer and must be free of defects that would cause 
localized hotspots and early corrosion failure. 
Nondestructive evaluation of bonds has long been 
made by ultrasonic tests, in which acceptance or 
rejection of a bonded element is based on its ability to 
transmit or to reflect ultrasound. However, no corrëla-
tion between thermal conductance of the bond and 
ultrasonic transmission has been previously estab- 
lished.
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per- 
son 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 the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000037 2020-03-11T20:17:40+00:00Z
more realistic acceptance standards for bonded reactor 
fuel plates. 
How it's done: 
To determine the thermal properties of the bonded 
elements, the thermal pulse method for measuring 
thermal diffusivity and thermal conductivity is 
utilized. The front surface of the specimen is uniformly 
irradiated by a very short pulse of radiant energy from 
a xenon flash tube. The temperature history of the 
back surface is continuously monitored by an oscil-
loscope, and the oscilloscope trace is photographed. 
The thermal conductivity, K, of the material is deter-
mined from:
K = aQ/LTM 
where 
a is the thermal diffusivity, and is determined 
from sample thickness and half-rise time 
Q is the amount of energ2 falling on the front 
surface 
L is the thickness of the sample 
TM is the maximum temperature rise of the back 
surface 
To determine the ultrasonic transmission of the 
bonded elements, a setup that closely duplicates the 
typical ultrasonic nondestructive test setup for bond 
testing plates is utilized. Tests are made at 1.0, 2.25, 
and 5.0 Mc. The output is fed into a dual-trace oscil-
loscope, and the amplitude of the transmitted pulse is 
obtained from the oscilloscope. 
For each specimen studied, the following values 
are obtained and plotted: 
- amplitude of the transmitted pulse of specimen 
NA - amplitude of the transmitted pulse of standard 
thermal conductivity of specimen - 
N  - thermal conductivity of standard
Notes: 
I. The relationship between thermal conductivity and 
ultrasonic transmission is frequency dependent. 
The rate of loss of ultrasonic transmission increases 
as the wavelength decreases. 
2. Before specimens are tested, they are examined 
radiographically so that a wide range of bond 
quality can be selected. 
3. Additional details are contained in the following 
references: 
(a) Applied Materials Research, July 1966, pp. 
162-167. 
(b) "Correlation of the Heat Transfer Properties 
and Ultrasonic Transmission Properties of 
Bonds," by R. A. DiNovi, ANL7074, February 
1966. This report is available from Clearing-
house for Federal Scientific and Technical 
Information, Springfield, Virginia 22151; price 
$3.00 (microfiche $0.65). 
4. Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B67-10037 
Source: R. A. DiNovi
Metallurgy Division
(A RG-247) 
Patent status: 
Inquiries about obtaining rights for commercial use 
of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 67-10037	 Category 02


Correlation established between heat transfer and ultrasonic transmission properties of copper braze bonds

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