Technique detects voids greater than or equal to 0.1016 cm in braze depths of 0.254 cm, detecting voids of smaller dimensions is possible. Internal design ensures control of beam's water path length to within 0.635 cm, this length is critical to system's accuracy

Peterson, R. M.

English

NASA Technical Reports Server

Bad Bond (On One 
Side Of Joint) - 
Signal Shear Wave 
At Unbonded Braze 
Echoes Back To 
Transducer 
March 1971	 Brief 7l-10045 
• gt3Gvco\
AEC-NASA TECH BRIEF 
YES	 Space Nuclear SystemsOJjice 
AEC-NASA Tech Briefs announce new technology derived 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 
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. 
Ultrasonics Used for High-Precision Nondestructive Inspection of Brazed Joints 
Brazed joints can now be inspected nondestructively 
with a high degree of precision using a new method 
involving ultrasonics. Earlier ultrasonic equipment 
was too cumbersome to allow accurate, easy aiming of 
the sound beam. With the new technique, however,
If the beam is considerably defocused when the 
mirror position is changed, it can be refocused by 
adjusting the position of the transducer, a lithium sul-
fate long-focus transducer operating at 2.25 MHz. 
Rocket-Nozzle Wall 
Fixture Assembly	 /	 L Transducer _ Fr-- 
Water,-,	 U-Tube 
Plexiglass 
Windows, 
Mirror 
Block
	 Bonded 
Teflon 
V-Guide.
Good Bond—
Signal Through 
Bonded Section 
Continues On
voids of > 0.1016 cm (^! 0.04 in.) in depth have been 
detected in braze depths of 0.254 cm (0.10 in.), and de-
tecting voids of smaller dimensions is possible. 
An ultrasonic mirror "fixture" is used to aim the 
beam without having to move the entire beam struc-
ture. The fixture consists Of an ultrasonic transducer 
and a polished aluminum mirror block-mounted in a 
sealed chamber. The mirror can be rotated and 
moved longitudinally, and the beam can be easily 
aimed within 0.875 x 102 rad (0.5 deg) after the fixture 
is in approximate position.
Coupling water is pumped through the fixture. 
Careful internal design ensures control of the beam's 
water path length to within 0.635 cm (0.25 in.). This 
length is critical to the accuracy of the system. 
Notes: 
1. For a Hastelloy X rocket nozzle 1.5 in (5 ft) in 
diameter, 1.8 m (6 ft) long and 1.016 cm (0.40 in.) 
thick, the method described plotted 250,000 data 
points in the inspection of 685.8 m (2250 ft) of braze 
joint. Every unsatisfactory bond was detected. 
(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=19710000045 2020-03-17T02:18:37+00:00Z
Requests for further information may be directed to: 	 Patent status: 
Technology Utilization Officer	 No patent action is contemplated by the AEC or 
AEC-NASA Space Nuclear Systems Office 	 NASA. 
U.S. Atomic Energy Commission
	
Source: R. M. Peterson of ur Washington, D.C. 20545	
jet-General Corp. Aero Reference: B71-10045	
under contract to 
AEC-NASA Space Nuclear Systems Office 
(NUC-10352)
. 
Brief 71-10045	 Category 08


Ultrasonics used for high-precision nondestructive inspection of brazed joints

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