The analysis of heat transfer through thermal-insulating materials

VACUUM Classified A b s t r a c t s

II

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Vacuum Apparatus and Auxiliaries

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-

II

Contd

26 --

MATERIALS

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26

144/'II

The A n a l y s i s of H e a t Transfer t h r o u g h T h e r m a l - I n s u l a t i n g Materials See A b s t r a c t No

202/I

145/II

On New Methods of I n s u l a t i n g Very Low T e m p e r a t u r e A p p a r a t u s See A b s t r a c t No

Abstract, No.

and References

202/I

Metal Coatings on Glass or Quartz Not Intended for Mirrors or Decoration See Abstract N o 85/IV

146/II

Method of F o r m i n g a V a c u u m - T i g h t Bond Between Ceramics a n d Metals

t47/H

Swztzerland V a l v e s for u l t r a s h o r t w a v e s are p r e f e r a b l y m a d e from b u r n t r e f r a c t o r i e s s uc h as s t e a t l t e Glass, t h e a l t e r n a t i v e m a t e r i a l , does n o t w i t h s t a n d t h e h i g h electric stress A n i m p o r t a n t process in t h e m a n u f a c t u r e of t h e s e v a l v e s is t h e v a c u u m - t i g h t b o n d i n g of t h e c e r a m i c t o m e t a l One of t h e m e t h o d s k n o w n consists of m e t a l h s m g t h e c e r a m i c a n d s u b s e q u e n t l y b r a z i n g t h e m e t a l c o m p o n e n t on t o t h e m e t a l h s e d surface The m e t a l l a y e r is s p r a y e d on or b u r n t in Thzs m e t h o d is c o m p l i c a t e d a n d of l i t t l e p r a c t i c a l use T h e n e w m e t h o d p r o p o s e d in t h i s p a t e n t is s i m p l e r I t is b a s e d on t h e o p e r a t i o n of p r e s s i n g t h e m e t a l a n d t h e c e r a m i c t o g e t h e r at an elevated temperature This h a s b e e n found t o r e s u l t in a v a c u u m - t i g h t b o n d The temperature and pr essu res u sed c a n be v a r i e d , b u t t h e lower l i m i t s of b o t h are d e t e r m i n e d b y t h e c o n d i t i o n s u n d e r w h i c h t h e m e t a l b e c o m e s p l a s t i c A n o t h e r i m p o r t a n t factor is t h e t i m e a l l o c a t e d t o t h e p r e s s i n g o p e r a t i o n F o u r a p p l i c a t i o n s of t h e process are d e s c r i b e d I n one a p p l i c a t i o n c oppe r c o v e r e d w i t h c upri c o x i d e Is h e a t e d u n t i l red hot, a n d t h e n d i p p e d i n t o w a t e r As a r e s u l t t h e c u p r i c oxi de c h a n g e s Int o c u p r o u s oxi de P r e s s i n g is c a rri e d o u t in a n l t t o g e n a t m o s p h e r e T h e t e m p e r a t u r e is 1,000°C a n d t h e p r e s s u r e is 3,000 lb sq i n c h After a t r e a t m e n t l a s t i n g a few seconds t h e c o m b i n e d m a t e r i a l shows a h i g h e r t e n s i l e s t r e n g t h t h a n t h e b a r e s t e a t l t e Somma~re M d t h o d e c o n s l s t a n t en l ' a p p h c a t l o n d ' u n r e c o u v r e m e n t m d t a l h q u e s ur de l a c d r a m t q u e en e o m p r i m a n t u n m a t d r i e l sur l ' a u t r e en v u e d ' o b t e m r u n lOlnt r d s l s t a n t a u v i d e

28 --

APPARATUS

COMPONENTS

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28 148/II

A Quick Release Seal for V a c u u m Desiccators

Abstract N o

158/11 149/II

Shaft Seal for V a c u u m A p p a r a t u s U m t e d States. A l t h o u g h t h e r e are a g r e a t m a n y s h a f t seals a v a i l a b l e r e a d y - m a d e , t h e r e s e a r c h w o r k e r h a s still t o r e s o r t f r e q u e n t l y t o f a b r i c a t i o n In order t o s a t i s f y his r e q u i r e m e n t s T h e a u t h o r s describe t h e de s i gn of a s h a f t seal s i m p l e t o f a b r i c a t e a n d s u i t a b l e for d r i v i n g t h e s t i r r e r of a p o t s t i l l I t consists of a drill rod l 0 i n c h long, r o t a t i n g inside a glass c a p i l l a r y O r i g i n a l l y a n oversize rod w a s g r o u n d d o w n t o fit a selected c a p i l l a r y B u t g r i n d i n g p r o v e d i m p r a c t i c a b l e I t was decided, therefore, t o m a t c h one of a s e l e c t i on of rods a g a i n s t a p r e c i s i o n - b o r e glass c a p i l l a r y , o m i t t i n g t h e g r i n d i n g o p e r a t i o n a l t o g e t h e r Thi s w a s successful, a n d t h e a u t h o r s n o w keep a few dozen steel drill rods of n o m i n a l d i a m e t e r 0 081 i nc h in s t o c k W h e n e v e r a n e w seal as r e q u i r e d t h e s e are m a t c h e d w i t h glass c a p i l l a r y t u b i n g of a n i ns i de d i a m e t e r of 0 081 i n c h ± 0 0 0 0 l i nc h N o r m a l l y , t h e rod h a s a c l e a r a n c e of 0 0001-0 0002 i n c h i n t h e b e a n n g A c up s h o u l d be f i t t e d a t t h e t o p of t h e a s s e m b l y t o hold a few drops of s e a l i n g fluid T e s t s h a v e s h o w n t h a t t h e d r i v e o p e r a t e d for m o n t h s w i t h o u t w e a r a t sp eeds u p t o 4,000 r p m D1-2-ethyl h e x y l p h t h a l a t e w a s used as t h e l u b r i c a n t ~omma,re

F. Tank, & Gos Fo;.rd Forsch. Etdg Techn ttoeh Zuermh U 8 Pat. 2,564,738

D e s c r i p t i o n d ' u n p r e s s e - d t o u p e utlhsd d i n s u n a p p a r e l l ~. di s t i l l e r m u m d ' a g l t a t e u r

Note b) D J Trevoy & W A Torpey Analyt Chem 24, Aug 1952, 1382

15o/ii

A High Speed Rotary Vacuum Seal U m t e d States F e w seals are a v a i l a b l e w h m h p e r m i t t h e i n t r o d u c t i o n of r a p i d r o t a t i o n a l m o t i o n Into a h l g h l y e v a c u a t e d s y s t e m A seal is d e s c r i b e d in t h i s n o t e w h i c h is s a t i s f a c t o r y a t speeds up t o 18,000 r p m for s h o r t periods, a n d has a f a i r l y long service life a t speeds u p t o 6,000 r p m I t is l e a k t l g h t for p r e s s u r e s as l ow as 10 -6 m m H g a g a i n s t a t m o s p h e r e T h e design p r o v i d e s for t h e use of t w o K l o z u r e seals w i t h a g u a r d v a c u u m b e t w e e n t h e m w h i c h is p r o d u c e d a n d m a i n t a i n e d b y a r o t a r y p u m p I n t h i s w a y t h e i n n e r K l o z u r e is r e l i e v e d of m u c h of t h e f r i c t i o n a l wear, u s u a l l y experienced, a n d c a n m a i n t a i n t h e v a c u u m m t h e s y s t e m e v e n if t h e o u t e r K l o z u r e w e a r s o u t d u r i n g a r u n D e t a i l s of t h e de s i gn are g i v e n a n d a n i l l u s t r a t i o n m s h o w n T h e d r i v i n g s h a f t is a b o u t t i n c h d i a m e t e r All c o m p o n e n t s are a s s e m b l e d i n a c y l i n d r i c a l b r a s s case w h m h xs b u i l t i n t w o p a r t s t o f a c i l i t a t e r a p i d s t r i p p i n g of t h e seal T h e o u t e r case is a t t a c h e d t o t h e e v a c u a t e d vessel. Cooling

October, 1952

Vacuum Vol I I No 4

421