Process for joining porous metal material to solid metal structure without cracking or blockage of porous component is described. Procedures of electron beam welding and electroforming are discussed. Illustration of microstructure resulting from process is included

Fortini, A.

Tulisiak, G.

English

NASA Technical Reports Server

December 1972	 B72-10754 
NASA TECH BRIEF 
is	 Lewis Research Center 	 0 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage P 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. 
Joining Porous Components to Solid Metal Structures 
The problem: 
To join a porous metal material to a solid metal 
structure without cracking and blockage of the porous 
component. Electron beam welding the porous com-
ponent directly to the solid metal causes cracks in the 
weld area. Brazing a solid material directly to a porous 
material cannot be done easily because the braze 
infiltrates the pores causing contamination and blockage.
Solutions: 
I. Electron beam buttering (surface welding) the surface 
of the porous material, followed by brazing or 
electroforming of the porous component to the solid 
metal structure. 
2. Electroforming a thin layer of metal to the surface of 
the porous material, followed by brazing of the 
porous component to the solid component. 
S
.	
.	 ,1	 .	 •,	 II. 
: 	 -	
t t 
Oil 
\	 1	 Solid Metal Component
 
•	 $ .
	 ,	
...	 ..	 j ..	 .	 .	 : 
.	 A.1	 ttA....	 .	 111111 'A 
Bond (Brazed Area)
	 - 
R	 ')L
Electron-Beam Buttered Area 
Porous Metal Component 
•	
s4_.$.. 
:.	 A
continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 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=19720000753 2020-03-17T03:40:53+00:00Z
final structure is to be used, the time required to perform 
the joining operation, etc. 
3. Electroform joining the porous component directly 
to the solid metal structure. 
How it's done: 
The joining operation is accomplished in one or a 
series of steps. 
In the first technique listed, the surface of the porous 
component is sealed by melting a thin outer layer of 
the porous material with an electron beam so that the 
melted material fills all outer surface pores. The thick-
ness of the surface coating may be varied from 0.025 
mm to 1.3 mm (1 to 50 mils) by varying electron beam 
power. The porous metal component can then be either 
brazed or electroformed to the solid metal structure. 
Although electroforming is a slower process (depositing 
0.025 mm or 1/1000 inch of metal per hour), it is 
inherently a cheaper process and is often preferred 
when compared to the complications which may be 
involved in brazing. As the micro-photograph shows, 
this joining technique produces a good bond without 
cracks and without contamination of the porous ma-
terial. 
More recently, this joining technique has been modi-
fied by electroforming a thin layer of metal to the 
surface of the porous material and then brazing the 
porous metal component to the solid metal structure. 
Alternately, the braze cycle can be eliminated by 
joining the porous component directly to the solid 
metal structure in a one-step electroforming operation. 
The choice among the three techniques depends on 
various factors such as the size of the pores in the 
porous material, the type of metals being joined, the 
conditions (temperature, pressure) under which the
Notes: 
1. This joining technique can be applied to the fabrica-
tion of filters and/or transpiration cooled bodies 
such as turbine blades,jet engine combustors, nozzles, 
and rocket chambers. 	 - 
2. Additional information is contained in NASA Tech 
Brief 68-10331, "Electron Beam Selectively Seals 
Porous Metal Filters." 
3. The following documentation may be obtained from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: NASA CR-72994 (N71-38071), 
Characterization of Porous Metal Matrices for 
Transpiration Cooled Structures 
Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B72-10754 
Patent status: 
NASA has decided not to apply for a patent. 
Source: Anthony Fortini and George Tulisiak 
Lewis Research Center
(LEW-112 59) 
B72-10754	 Category 08, 04


Joining porous components to solid metal structures

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server