Brazing process employs an aluminum-silicon filler alloy for diffusion bonding of aluminum parts in a vacuum or inert gas atmosphere. This process is carried out at temperatures substantially below those required in conventional process and produces bonds of greater strength and reliability

Beuyukian, C. S.

Johnson, W. R.

English

NASA Technical Reports Server

June 1966	 Brief 66-10241 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Brazing Process Using Al—Si Filler Alloy Reliably Bonds Aluminum Parts 
The problem: 
To develop an improved method for metallurgically 
bonding aluminum parts. Conventional fluxes which 
have been used for brazing aluminum evolve objec-
tionable fumes in the brazing furnace and necessitate 
the expenditure of time and effort to remove excess 
flux after brazing is completed. Bonds formed between 
aluminum parts by the silver diffusion process often 
fail to pass high-pressure leak tests, and parts which 
pass the tests must be given a protective coating to 
prevent cathodic corrosion of the aluminum. 
The solution: 
A process employing an aluminum-silicon filler 
alloy containing from 7.5 to 12% silicon for diffusion 
bonding of the aluminum parts in a vacuum or an 
inert gas atmosphere. 
How it's done: 
Parts to be bonded are chemically, cleaned to re-
move all contaminants from the mating surfaces. The 
cleaned surfaces may either be clad with the aluminum-
silicon alloy or interleaved with this material. The 
filled parts are placed into an open steel envelope 
whose inner surfaces are separated from the parts by 
aluminum or steel sheets. The envelope is then sealed 
by welding its open edges to ensure leaktight joints, 
as determined by a helium leak test, and evacuated to 
eliminate gaseous contaminants. The evacuated en-
velope is heated by any suitable means to a tempera-
ture ranging from 1045 0 to 1110°F, which is then 
maintained for a sufficient time for completion of the
diffusion bonding process. At the end of this time, 
heating is discontinued and the envelope is allowed 
to cool to room temperature. The envelope is then 
opened and the bonded structure is removed. The 
rate of cooling will depend on the configuration and 
mechanical properties of the completed aluminum 
structure. 
Notes: 
I. Parts of certain configurations may require that the 
envelope be purged and backfilled with an inert 
gas, instead of being evacuated. 
2. This relatively inexpensive process is carried out at 
temperatures substantially below those required in 
conventional processes and produces bonds of 
greater strength and reliability. 
3. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Manned Spacecraft Center 
Houston, Texas, 77058 
Reference: B66-10241 
Patent status: 
No patent action is contemplated by NASA. 
Source: C. S. Beuyukian and Wayne R. Johnson 
of North American Aviation, Inc. 
under contract to 
Manned Spacecraft Center 
(MSC-448) 
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.
https://ntrs.nasa.gov/search.jsp?R=19660000240 2020-03-11T17:32:05+00:00Z


Brazing process using'al-Si filler alloy reliably bonds aluminum parts

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