Quasi-fluids permit hydrostatic extrusion of solid materials. The use of sodium chloride, calcium fluoride, or glasses as quasi-fluids reduces handling, corrosion, and sealing problems, these materials successfully extrude steel, molybdenum, ceramics, calcium carbonate, and calcium oxide. This technique also permits fluid-to-fluid extrusion

Hunt, J. G.

Rice, R. W.

English

NASA Technical Reports Server

September 1970	 Brief 70-10428 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
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be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
High-Temperature "Hydrostatic" Extrusion
Liner
Metal Nose
ww
Die 
Thin Metal Shell 
Insulating Can for Hydrostatic Extrusion 
The effect of hydrostatic extrusion (refs. 1-3) can 
be approached by extrusion with use of solids that 
are very much softer than the materials extruded; the 
former are quasi-fluids relative to the latter. The use 
of such solids as NaCl, CaF,, or glasses as quasi-
fluids, somewhat below their melting points, substan-
tially reduces handling, corrosion, and sealing 
problems. Fluid-to-fluid extrusion is also possible by 
use of this technique; the isotactic back pressure can
be controlled by the extrusion of a second soft solid 
through a second extrusion die. 
Since the solid quasi-fluid can be heated with the 
billet separate from the press, it can have a higher 
temperature than the press liner (which is typically 
at only 400°C); thus the quasi-fluid helps to insulate 
the core material before and after extrusion. 
The fact that a metal sheath is often needed to pre-
vent contamination of the core by the quasi-fluid 
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presents no problem. The sheath has led to the use of 
the insulating-can concept (see fig.) which was con-
ceived and developed for extrusion of ceramics in 
thick-walled metal cans by conventional techniques. 
Use of a double-walled thin metal can, with the inter-
wall space filled with a suitable ceramic powder, pro-
vides still more insulation. The layer of powder 
provides an additional barrier against the quasi-fluid 
in the event of a leak in the outer wall of the can. Com-
monly the powder is of the same composition as the 
core which is compatible with the chosen materials 
of the can; usually it is at >50% of theoretical density. 
Tests have shown that steel and molybdenum can 
be extruded with NaCl and CaF 7 , respectively, used 
as the quasi-fluids; and that ceramics can be extruded 
by use of CaF, as the extruding fluid and of NaCl as 
the receiving fluid. Calcium carbonate (in a steel can) 
was extruded successfully by use of NaCl as the quasi-
fluid; CaO at about 1150°C, by use of CaF,. A 200° 
to 400° higher temperature would have prevented 
some cracking that occurred in the CaO; this higher 
temperature would still be usefully lower than the 
1800°C that is needed for extrusion of CaO in a thick-
walled can.
Reference: 
1. Beresnev, B. I.: Vereshchagin, L. F.; Ryabinin, 
L. N.: and Livshits, L. D.: Large Plastic Deforma-
tion of Metals at High Pressures. Akad. Nauk 
Press, Moscow, 1960. 
2. Pugh, H. L. D.; and Low, A. H.: The Hydrostatic 
Extrusion of Difficult Metals. J. Inst. Metals, vol. 
93, March 1965, pp. 201-217. 
3. Fiorentino, R. J.; Sabroff, A. M.; and Doulger, 
F. W.: Investigation of Hydrostatic Extrusion. 
Tech. Report AFM L-TR-64-372, Jan. 1965. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP70- 10428 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: J. G. Hunt of

Nuclear Metals, Incorporated,

and R. W. Rice of

The Boeing Company

under contract to

NASA Pasadena Office

(N PO- 1081 1) 
Brief 70-10428	 Category 08


High-temperature ''hydrostatic'' extrusion

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