Creator:A.P. Young, P.R. Robbins, and C.M. Schwartz
Date Created:June 1962
Place Created:Columbus, Ohio
Keywords:high-pressure and temperature devices
Context:article submitted to Journal of Scientific Instruments
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-L> 0 ~IROLE	-P- ire
HIGW-TEMPEAATVftE DEVTC- FQP P«ESS»J»ES
4. P. Young, P. ftoobi n» and C« m. Schwartz
BATTELLE tiEMOaiAi. INSTITUTE Columbus 1, Ohio
The "girdle1 ultra-Mgft-pressj re device as originally described1 called for either Iron oxide powder or pr»»aoe*pres»ible gaskets for insulation between tha olstons and d<e. The effect of gaskets on the efficiency and ultimate sample pressure attainable in the girdle was not discussed. An apparatus ueing coomressibia gaskets, described by Daniels and Jones2* was similar to the girdle. The hiqhes* pressure mentioned in the description of the Daniel's device was 10C?000 kg/em2 on the Bridgmar teal a or approximately 75 kb on the Kennedy sc«le\
It has been possible by use o* special qype oaskats to obtain sample pressures to anout i*C kb in » nodi fled girdle apparatus. At about 120 kb and 1200 C, stishovlte4' tha mtUe-type hiqh-pressure modification c? SlC^t produced in this apparatus.
The piaton-di^-binding rino assembly in the revised girdle is essentially similar to that described previously^. The truncated cone portion of the pistols has a SSC cone anole and i/?-inch piston face.
A	.	,
The die is made with a cone angle, 1/2-inch-bore iiatteter and 1/4-inch-bore height. Tungsten carbide with 6 per cent cobalt Binder Is used for the pistons. The die is made of Carpenter Hampden steal hardened to Rockwall C 60-63. The use of an expandable steel die instead of a
tungsten carbide die is an important feature of the girdle apparatus. ----
* Supported by Atomic Energy Commission.
The changes revolting In increased efficiency end higher ultimate sample pressure in the girdle modification are in the specimen cell and the gasket configuration. A schematic of tha specimen cell and gaskets used in synthesizing $ti»hovite are shown In Figure 1. An essential
part of the assembly la tha polvethyxane films separating the gaskets
from t-e <.* er.d pis* 1. The li*s i ,t 01 'n-ir-h -jo ly ethylene
sheets
precut and joined at the edge by pressu-e and heat to form cones.
In synthesizing stlshovite, a 1/16-inch I.D. platinum tube with wall thickness was used bots as container and heater. Electrical contact was made on either and to the piston via a 0.005-inch platinum disk, a steel washer with pyrophvllite insert and steel disk as shown ift Figure 1. The heater requirements for this synthesis wer-e 675 j.isperes and 0.92 volts, and the oress load was 300 tons.
For pressure calibration, a cylinder of sllvej chloride enclosing an axlel metal wire was substituted for the platinum tube. Resistance versus pressure was determined for bismuth, iron and barium. The blsmmth VI-VII transition occurred at 210 tons press load. Sharp discontinuities were not observed in iron and barium above 200 ton* press load. There
was however the beginning of a rapid increase in resistance with pressure
3)0	3/o
at about •af-j tons press load in beri r »nd abou	tons in iron. If
the PrickameT* values of 90 kb for the bismuth VI-VIII, 130 kb for iron
and 144 kb for the upper berlue transitions are used* the s«aple pressure
required for stlthovlte synthesis was about 120 kb. This agrees with
Stishov's estimate if his figure of 160,000 atm u converted to the Kennedy
scale.
Apprcxijwta sas^l* tlfftur* *t high j>r«**«x« i« dtt»rain*j fro® h««t«r *«ttage. For analytical purposes It i* tUairaM* to <a«a»ur« k^apl* t«»p«ratare at pressor®. *ork is In srograae on ••thods of bringing out
RhFE,R£NC£S
1.	«. B.	Raw. Scl. lMtr.» 331 (I960)*
2.	ML B. Danials and M. T. Jonas, Rav. Scl. !Mtr«, 935 (1961).
3.	G. C. Kannady ana P. N. L**©rl, frcaraaa 1ft Vfrv High	R»»arch
John ill ay & Sons, York, 1961 p. 304.
7U~r Awa fJL^U^ ^Jfti^ i sJLt-
4.	S. M. Stiahov and S.«V. Popov*, GaakhUlya, SJ7'(l96l).
5.	F. C. T» Chao, J. J. Fahay, J. Littlar, and D. J. Milton, J. Gaophy*. rej Raaaarch, ft, 419 (1962).	' &
6.	A. S. Balchan and H. G. Drickwr, Fay. Sel. Tnatr., 306 (1961).
TUNGSTEN CARBON PISTON
-POLYETHYLENE
PYROPHYLLITE
•STEEL
-PYROPHYLLITE
-POLYETHYLENE
-STEEL
PYROPHYLLITE
■PLATINUM
-PYROPHYLLITE
STEEL-
SAMPLE-
PLATINUM TUBE-
Ml