Measurement of the thermal diffusivity of liquid oxides and metallurgical slags
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. (cm2/s). '
A t h e o r e t i c a l b a s i s is used to develop the f o r m of this r e l a t i o n s h i p , and c o n s e q u e n t l y , it should y i e l d r e a s o n a b l e e s t i m a t e s for g l a s s e s of other c o m p o s i t i o n and at o t h e r t e m p e r a tures. T H E s l a g in m a n y m e t a l l u r g i c a l o p e r a t i o n s m a y p a r t i c i p a t e to an a p p r e c i a b l e extent in the heat t r a n s f e r p r o c e s s e s o c c u r r i n g within the s y s t e m . Heat t r a n s f e r i n l i q u i d g l a s s e s and s l a g s can o c c u r by conduction, c o n v e c t i o n and r a d i a t i o n . It was the p u r p o s e of the i n v e s t i g a t i o n r e p o r t e d h e r e to study the c o m b i n e d effects of conduction and r a d i a t i o n heat t r a n s f e r in g l a s s e s s i m i l a r to m e t a l l u r g i c a l s l a g s . P r e v i o u s s t u d i e s of c o m b i n e d c o n d u c t i o n and r a d i a tion heat t r a n s f e r in d i a t h e r m a n o u s m a t e r i a l s * have *Materialstransparentto infraredradiation. b e e n l i m i t e d to s u b s t a n c e s with low a b s o r p t i o n c o e f f i c i e n t s , such as g a s e s , window g l a s s , and tanks of liquid g l a s s c o n t a i n i n g low c o n c e n t r a t i o n s of i r o n oxides. The r e s u l t s of t h e s e i n v e s t i g a t i o n s i n d i c a t e that at high t e m p e r a t u r e s , the d o m i n a n t m e c h a n i s m of heat t r a n s f e r in the bulk m a t e r i a l is " r a d i a t i o n c o n d u c t i o n " . However, for g l a s s e s c o n t a i n i n g l a r g e a m o u n t s of f e r r o u s ions, the m e a n f r e e path of photons within the g l a s s m a y d e c r e a s e to the extent that r a d i a t i o n conduction no l o n g e r is d o m i n a n t . 1 A new p e r i o d i c s t e a d y - s t a t e t e c h n i q u e has b e e n d e v e l o p e d in this work for m e a s u r i n g the effective t h e r m a l diffusivity of liquid g l a s s e s s i m i l a r to m e t a l l u r g i cal s l a g s . G l a s s e s c o n t a i n i n g b e t w e e n 10.9 and 26.8 pct F e O and having l i m e / s i l i c a r a t i o s of 1.0 and 1.5 have b e e n studied at t e m p e r a t u r e s up to 1500~ Measurem e n t s of r a d i a t i o n t r a n s m i s s i o n at r o o m t e m p e r a t u r e also have b e e n m a d e on g l a s s e s c o n t a i n i n g 0 to 12.6 pct F e O to d e t e r m i n e the m o n o c h r o m a t i c a b s o r p t i o n c o e f f i c i e n t s for the v i s i b l e and i n f r a r e d s p e c t r a , and to e s t a b l i s h the m i n i m u m s i z e of s a m p l e s that could be used in the d i f f u s i v i t y e x p e r i m e n t s . H. ALAN FINE, Assistant Professor, Department of Metallurgical Engineering, University of Arizona, Tucson, AZ, is a Junior Member, ASM & AIME. T. ENGH is Associate Professor, Department of Metallurgy, The Norwegian Institute of Technology, Trondheim, Norway, and JOHN F. ELLIOTT, a Fellow of TMS and of ASM i
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