Normal spectral emittance of vanadium and tantalum for different surface conditions at temperatures above 1000 K
- PDF / 680,246 Bytes
- 4 Pages / 612 x 783.28 pts Page_size
- 93 Downloads / 201 Views
Iowa. 50010. Manuscript submitted December 10, 1973. METALLURGICAL TRANSACTIONS
p e r a t u r e b e t w e e n 1170 and 1970 K at a p r e s s u r e of 5 • 10 -6 m m Hg. V o r o n i n e t al. 5 and P e l e t s k i i et al. 6 have also found the n o r m a l s p e c t r a l e m i t t a n c e (X = 0.65~) of polished v a n a d i u m r o d s to d e c r e a s e l i n e a r l y with i n c r e a s i n g t e m p e r a t u r e b e t w e e n 1100 and 1800 K at p r e s s u r e s a r o u n d 10 -6 m m Hg. Bonnell e t al. 7 have m e a s u r e d the n o r m a l s p e c t r a l e m i t t a n c e (~ = 0.645~t) of m o l t e n v a n a d i u m at its m e l t i n g point while the s a m ple is l e v i t a t e d in an a r g o n a t m o s p h e r e . Worthing 8 m e a s u r e d the n o r m a l s p e c t r a l e m i t t a n c e (~ = 0.463 and 0.665~t) of t a n t a l u m f i l a m e n t in v a c u u m and found it to d e c r e a s e l i n e a r l y with t e m p e r a t u r e f r o m 300 to 3290 K. Malter and L a n g m u l r 9 noted the n o r m a l s p e c t r a l e m i t t a n c e (X = 0.665/z) of a t a n t a l u m w i r e to d e c r e a s e with i n c r e a s e in t e m p e r a t u r e f r o m 1000 to 3270 K. F i s k e 1~ also o b s e r v e d the n o r m a l e m i t t a n c e of t a n t a l u m f i l a m e n t in v a c u u m to d e c r e a s e with i n c r e a s e in t e m p e r a t u r e in the r a n g e 1250 to 2400 K. Betz et al. ~ d e t e r m i n e d the n o r m a l s p e c t r a l e m i t t a n c e (~ = 0.665) of t a n t a l u m tubes with d i f f e r e n t p r e t r e a t m e n t s like m e c h a n i c a l polishing, c l e a n i n g with a liquid d e t e r g e n t and oxidation at r e d heat in a i r in the t e m p e r a t u r e r a n g e 1100 and 1800K at 5 • 10 -4 m m Hg. They found the e m i t t a n c e for each c a s e to d e c r e a s e l i n e a r l y with i n c r e a s e in t e m p e r a t u r e . Allen et al. ~2 found the n o r m a l s p e c t r a l e m i t t a n c e of v a c u u m cast t a n t a l u m which has b e e n p r e s s e d and s i n t e r e d f r o m t a n t a l u m powder in an a r g o n a t m o s p h e r e to d e c r e a s e s l i g h t l y with i n c r e a s i n g t e m p e r a t u r e f r o m 1120 to 2700 K. Allen 13 made s i m i l a r m e a s u r e m e n t s on t a n t a l u m tubing b e t w e e n 2400 and 3200 K. P e a r s x4 also d e t e r m i n e d the n o r m a l s p e c t r a l e m i t t a n c e of t a n t a l u m s u r f a c e ground to a smooth finish u n d e r a d r y a r g o n a t m o s p h e r e , b e t w e e n 2380 and 2660 K. S e r e b r y a k o v a et al. xS, K h r u s t a l e v e t al. ~6 and K o t l y a r et a l . x7 have m e a s u r e d the n o r m a l s p e c t r a l e m i t t a n e e (~, = 0.65/z) of t a n t a l u m t u b e s u n d e r v a c u u m b e t w e e n 1100 and 3000 K and found it to d e c r e a s e with I n c r e a s e in t e m p e r a t u r e . M a r t t n e z and Madjtd 18 have d e t e r m i n e d that the n o r m a l s p e c t r a l e m i t t a n c e of a t h i n - w a l l e d t a
Data Loading...
