A TECHNIQUE FOR EQUATION STATE DETERMINATION OF LIQUID METALS AT HIGH TEMPERATURES AND PRESSURES

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A TECHNIQUE FOR EQUATION STATE

DETERMINATION OF LIQUID METALS AT HIGH TEMPERATURES AND PRESSURES

A. Berthault, L. Arles

To cite this version:

A. Berthault, L. Arles. A TECHNIQUE FOR EQUATION STATE DETERMINATION OF LIQUID

METALS AT HIGH TEMPERATURES AND PRESSURES. Journal de Physique Colloques, 1984,

45 (C8), pp.C8-301-C8-303. �10.1051/jphyscol:1984855�. �jpa-00224357�

JOURNAL DE PHYSIQUE

Colloque CS, supplément a u n O l 1, Tome 45, novembre 1984 page C8-301

A T E C H N I Q U E FOR E Q U A T I O N S T A T E D E T E R M I N A T I O N OF L I Q U I D M E T A L S A T H I G H T E M P E R A T U R E S A N D P R E S S U R E S

A . B e r t l i a u l t a n d L. A r l e s

Conunissar~ial à Z'hYzergie Atomique, B o î t e Postale 53:, 75752 Paris Cedex 15, France

Résumé

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comprises e n t r e 1500 e t 8000°K.

L ' é c h a n t i l l o n m é t a l l i q u e e s t contenu dans une e n c e i n t e r e m p l i e d ' a r g o n gazeux sous h a u t e p r e s s i o n e t e s t c h a u f f é p a r e f f e t j o u l e à l ' a i d e de l a décharge d ' u n banc de condensateurs. D u r a n t l ' e x p é r i e n c e , des mesures du c o u r a n t , de l a t e n s i o n e n t r e deux p o i n t s du f i l , de l a t e m p é r a t u r e e t de l a v a r i a t i o n de d i a - mètre du f i l , s o n t e f f e c t u é e s .

A b s t r a c t

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Conventional e x p e r i m e n t a l t e c h n i q u e s f o r measuring t h e r m o p h y s i c a l p r o p e r t i e s o f m a t e r i a l s a t h i g h temperatures and p r e s s u r e s a r e l i m i t e d by t h e sample r e a c t i v i t y and t h e s t r e n g h o f t h e p r e s s u r e vesse1 a t h i g h temperatures. The t e c h n i q u e d e s c r i b e d h e r e (1-2) i s used t o a c q u i r i n g t h e r m o p h y s i c a l d a t a f o r l i q u i d m e t a l up t o 0.6 GPa and temperatures f r o m 1500 t o 8000°K.

The e x p e r i m e n t a l procedure c o n s i s t s o f r e s i s t i v e l y h e a t i n g a 1 mm d i a m e t e r and 1 5 mm l o n g metal w i r e sample by d e c h a r g i n g a c r i t i c a l l y damped 60 K j c a p a c i t o r bank t h r o u g h i t . T h i s h e a t i n g i s q u i c k enough t o a v o i d t h e r a d i a t i v e h e a t l o s s e s and hydrodynamic i n s t a b i l i t i e s ( t < 100 u s ) and l o n g enough f o r t h e s k i n e f f e c t t o be n e g l i g i b l e and t h e sample c o n s t a n t l y v e r y c l o s e t o e q u i l i brium.

The sample i s s t a n d i n g i n an a r g o n - f i l l e d - v e s s e 1 designed w i t h f o u r s a p p h i r e windows f o r v i e w i n g t h e sample f r o m a r a d i a l d i r e c t i o n .

A general view o f t h i s e x p e r i m e n t i s r e p r e s e n t e d on f i g u r e 1.

D u r i n g an e x p e r i m e n t a l s h o t , c u r r e n t f l o w i n g i n t h e c i r c u i t , v o l t a g e d r o p across two p a r t s o f t h e w i r e , d i a m e t e r and t e m p e r a t u r e a r e measured.

The c u r r e n t f l o w i n g i n t h e c i r c u i t ( f i g . 2) i s measured w i t h a wide-band c u r r e n t t r a n s f o r m e r .

The v o l t a g e d r o p across two p o i n t s around t h e m i d d l e o f t h e w i r e ( f i g . 2) i s measured by high-impedance c i r c u i t t o m i n i m i z e c o n t a c t - r e s i s t a n c e problems and a d i f f e r e n c e a m p l i f i e r .

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1984855

C8-302 JOURNAL DE PHYSIQUE

Fig. 1

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'The volume change i s observed by shadowgraph w i t h a C.W. argon-ion l a s e r and streaking camera. A narrow-band interference f i l t e r i s put in front of camera t o dispose off the intense thermal radiation from the sample.

The temperature i s measured with a four channel optical pyrometer looking through a fourfurcated f i b e r o p t i c bundle a t the same spot on the sample image. The output of three of these f i b e r bundles a r e p u t in f r o n t of 100 nm bandwidth f i l t e r s centered a t 600, 750 and 900 nm respectively. When these three channels records are mixed, a variety of ways of calculating temperature a r e possible. The forth without f i l t e r channel i s t o allow measurement of small temperatures. 1 4 t h refractory metals the melting temperature i s assigned t o the plateau observed in the temperature records t o determine the r e l a t i v e emissivity of the material. From t h i s value a l l the other temperatures can be calculated.

About ten microseconds a f t e r the end of t h e current pulse a whole wire photograph i s taken with a Q-swithched ruby l a s e r t o put away a l l shot where the sample diameter i s not uniforme.

Current, voltage and pyrometric records a r e d i g i t a l i z e d and stored by waveform recor- ders. All t h i s numerical values a r e stored on floppy-disks.

F i g . 2 - T y p i c a l c u r r e n t , v o l t a g e and p y r o m e t r i c r e c o r d s versus t i m e f o r t a n t a l u m a t 0.2 GPa.

REFERENCES

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