THERMAL AND ENVIRONMENTAL EFFECTS ON CERAMIC FIBRES

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THERMAL AND ENVIRONMENTAL EFFECTS ON CERAMIC FIBRES

S. Karlsson, R. Lundberg, R. Carlsson

To cite this version:

S. Karlsson, R. Lundberg, R. Carlsson. THERMAL AND ENVIRONMENTAL EFFECTS ON CERAMIC FIBRES. Journal de Physique Colloques, 1986, 47 (C1), pp.C1-587-C1-591.

�10.1051/jphyscol:1986189�. �jpa-00225620�

JOURNAL DE PHYSIQUE

Colloque C1,

supplgment au n02, Tome 47, fbvrier 1986 page

CI-587

THERMAL AND ENVIRONMENTAL EFFECTS ON CERAMIC FIBRES

S. KARLSSON, R. LUNDBERG and R. CARLSSON

Swedish Institute for Silicate Research, Box 5403, S-402 29 Gothenburg, Sweden

RQsumG

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On a Q t u d i Q l ' u t i l i s a t i o n d ' i s o l a n t s f i b r e u x d a n s d e s f o u r s d ' i n d u s t r i e c s r a m i q u e . Les p r i n c i p a l e s p h a s e s c r y s t a l l i n e s d e s f i b r e s c o m p o r t a n t A1203 e t S i 0 2 s o n t l a c r i s t o b a l i t e e t l a m u l l i t e . La p r o p o r - t i o n d e p h a s e s c r i s t a l l i s 6 e s depend d e l a c o m p o s i t i o n c h i m i q u e e t d e l a t e m p Q r a t u r e d e t r a i t e m e n t . La c o n d e n s a t i o n d e v a p e u r s d e ZnO p r o v e n a n t d e s Qmaux e t l a f o r m a t i o n d e ZnA1204 o n t S t 6 o b s e r v Q e s s u r d e s f i b r e s S a f f i l e 2 930 O C .

A b s t r a c t - 2 i b r e i n s u l a t i o n s i n k i l n s i n t h e c e r a m i c i n d u s t r y were i n v e s t i g a t e d . C r i s t o b a l i t e and m u l l i t e a r e t h e main c r y s t a l l i n e p h a s e s found i n k1203-SiOZ f i b r e s . The amount o f t h e c r y s t a l l i n e p h a s e s formed d e p e n d s on t h e c h e m i c a l c o m p o s i t i o n and f i r i n g t e m p e r a t u r e . d o n d e n s a t i o n o f ZnG-vapours from t n e g l a z e and f o r n l a t i o n o f ZnA1204 were found i n a S a f f i l f i b r e a t a t e m p e r a t u r e o f 9 3 0 ~ ~ .

Ceramic f i b r e s have been used a s t h e n n n l i r i s u l a t i o n i n k i l n s f o r s e v e r a l y e a r s . A rlumber o f i n v e s t i g a t i o n s a b o u t c r y s t a l l i z a t i o r ~ , s i n t a r i n g , and s h r i n - k : ~ g e o f h e a t - t r e a t e d f i b r e s Gave b e e n p r e s e n t e d / I - 6 / . The i n f l u e n c e o f a t m o s p h e r e h a s t o some e x t e n t been s t u d i e d .

h e a t - t r s a t m e n t o f h1203-Si02 f i b r e s g i v e s n i u l l i t e and c r i s t o b a l i t c a s t h e main c r y s t s l l i n e p h a s e s . The amount o f t h e c r y s t a l l i n e p n a s e s formed depends on f i b r e c o ~ n p o s i t i o n , t e q e r a t u r e , and a t ~ n o s p h e r e . Tne c r y s t & l l i z a t i o n s d e e d de- Z r e a s e s a f t e r t h e f i r s t 10-20 h o u r s o f h e a t - t r e a t m e n t .

T h i s p a p e r p r e s e n t s i n v e s t i g a t i o n s o f c e r a m i c f i b r e s c o l l e c t e d from d i f f e r e n t t y p e s o f k i l n s used i n c e r a m i c i n d u s t r y i n Sweden. The bge o f t h e f i b r e s a s w e l l a s t h e f i r i n g c o n d i t i o n s i n t h e k i l n s v d r i e s . Tne r e s u l t s 2 r e s e n t e d a r e t h e f i r s t p a r t o f a p r o j e c t where t h e f i b r e p r o p e r t i e s w i l l be examined by t h e c o l l e c t i o n o f shmples st f i x e d i n t e r v d l s .

information a b o u t t h e p e r i o d i c a l k i l n s < h e r e f i b r e s a m p l e s werz t a k e n a r e sum- marized i n t a b l e 1 . Two o f t h e K i l n s , GSS 1 and GSS 3 , a r e o f t h e S h e l l e y t y p e

here t h e f i b r e s a r e p r o t e c t e d from t h e k i l n a t m o s p h e r e by a s i l l i m a n i t e t i l e . I n t i i e s e k i l n s a c y l i n d r i c s l sample *cis t a k e n from t h e h o t f a c e t h r o u g h t h e i n s u l a t i o n t o t h e s t e e l s h i e l d . The o t h e r k i l n s i n t a b l e 1 a r e s h u t t l e k i l n s o f v a r i o u s m a n u f a c t u r e . The f i b r e s were t a k e n from t h e h o t f a c e o f t h e i n s u l a - t i o n . Sorne f i b r e sdmples t a k e n from p s c k i n g s i n a t u n n e l k i l n were a l s o exami- ned. Chemical c o m p o s i t i o n and maximum t e m p e r a t u r e o f c o n t i n u o u s u s a o f t h e i n v e s t i g a t e d f i b r e s a r e g i v e n i n t a b l e 2.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1986189

JOURNAL

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PHYSIQUE

T a b l e 1

-

F i r i n g c o n d i t i o n s o f i n v e s t i g a t e d k i l n s .

GSS 1 GSS 7 K i l n

e l e c t r i c i t y 1 2 ~ 0 b i s c u i t

--

F i r i n g c o n d i t i o n s I n s u l a t i o n

F u e l Max. temp. (OC) Type F i b r e Age(cgc1es)

e l e c t r i c i t y 1200, b i s c u i t

propane 25 1400 g l a z e

b u t a n e 7 5 1060 g l a z e b i s c u i t e l e c t r i c i t y 1250 g l a z e p r o p a n e 9 5 1400 g l a z e

propane 95 11 50 b i s c u i t

Cerachrome

*

5Omm 6 0 0

C e r a f i b e r

*

6 3 m

l i b z r f r a x H

**

50.m 50'0 F i b e r f r a x

**

^63mm

S a f f l l

***

290

S a f f i l

***

1000-1 100

F i b e r f r a x H

**

450

C e r a f i b e r

*

425

T a b l e 2

-

P r o p e r t i e s o f i n v e s t i g a t e d f i b r e s .

C e r a f i b e r

*

1

F i b e r f r a x Cerachrome

** * 1

^{5 :!.}

F . i b e r f r a x H

**

⁶²

S a f f i l

***

_96-97

F i b r e S i 0 2 i r 2 0 3 ( r / o ) / Ilrx. temp. c o n t i n . u s e ( O C )

I

I A1203

The f l b r e s have been examlned by s c a n n l n g e l e c t r o n microscopy ( s E ~ ) and X-ray diffraction (XKD) and I n some c a s e s by X-rdy f l u o r e s c e n c e (XnF).

I

III

-

AESULTG

The f i b r e i n s u l a t i o n s which have been s t u d i e d seern i n g e n e r a l t o be v e r y i i t t - l e a f f e c t e d by t h e t e m p e r a t u r e and t h e a t m o s p h e r e i n t h e k i l n s . The s u r f a c e o f t h e f i b r e b l a n k e t s o r b l o c k s i s s o f t and e x c e p t tine S a f f i l f i b r e s o f unchangad c o l o u r . The S a f f i l f i b r e s i n k i l n s RH I and HK 2 have a l i g h t p i n k c o l o u r . I n t h e two k i l n s GSS 1 and GSS 3 t h e f i b r e i n s u l a t i o n i s p r o t e c t e d a g a i n s t t h e k i l n a t m o s p h e r e by a a i l l i m a n i t e t i l e . T h e r e f o r e o n l y m i n o r i n f l u e n c e from t h e k i l n a t m o s p h e r e on t h e a g e i n g and c r y s t a l l i z a t i o n b e h a v i o u r o f t h e f i b r e s is e x p e c t e d .

T a b l e 3 summarizes t h e c r y s t a l l i n e p h a s e s which have been found i n k1203-Si02 f i b r e s . The t a b l e shows t h a t c r i s t o b a l i t e and m u l l i t e a r e t h e main p h a s e s . :"iu- l i t e i s formed a t a lower t e m p e r a t u r e t h a n c r i s t o b a l i t e . The f i b r e s which h a v e b e e n c l o s e t o tk.e t i l e i n k i l n GSS 1 a r e c o m p l e t e l y c r y s t a l l i z e d . No remai- n i n g g l a s s p h a s e i s f o u n d , b u t t h e f i b r e s s t i l l have a g l a s s y a p p e a r a n c e . Com- p a r e d t o n o t c r y s t a l l i z e d f i b r e s t h e y a r e s l i g h t l y more deformed and b e n t , f i g u r e 1. T i e c r y s t a l l i n e p h a s e s formed depend on t h e c h e m i c a l c o m p o s i t i o n o f t h e f i b r e s . T h i s i s c l e a r l y s e e n i n k i l n s GSS 1 and GSS 3. The h i g h e r A1203- c o n t e n t i n t h e P i b e r f r a x H f l b r e c a u s e s f o r n s t i o n o f m u l l i t e a s t h e main p21s- s e . I n b o t h r h e k i l n s , t h e c r i s t o b a l i t e c o n t e n t h a s a maximum a b o u t 25 mm from t h e h o t f a c e . T h i s h a s a l s o been found i n o t h e r k i l n s n o t p r e s e n t e d h e r e . The f i r i n g c o n d i t i o n s o f k i l n RP d i f f e r s from t h e one i n t h e k i l n GSS 3. 3xa- m i n a t i o n o f a f i b r e sample s h o r s , however, t h a t t h e c r y s t a l l i z a t i o n beiiaviour seems t o be a l m o s t u n a f f e c t e d by t h e d i f f e r e n t f i r i n g c o n d i t i o r i s . The r e l a t i v e amounts o f t h e c r y s t a l l i n e p h a s e s fonned a s w e l l a s t h e m i c r o s t r u c t u r e a r e si- m i l a r . K i l n SB is a s h u t t l e k i l n u i t h a r e d u c i n g a t m o s p h e r e between 1950 and 1150 O C , f o l l o w e d by o x i d i z i n g a t m o s p h e r e d u r i n g t h e c o o l i n & p e r i o d . SLM and XHD d i d n o t r e v e a l any s p e c i f i c i n f l u e n c e o f t h e r e d u c i n g a t m o s p h e r e .

*

J o h n s i ~ I a n v i l l e

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L C 1

Table J

-

C r y s t a l l i n e phases i n n e a t - t r e a t e d k1207-Si02 f i b r e s .

b ^0, ,

Fiberfrax H Flbertrax

loo

h

Fibertrax

'1)

Ceraflber Hot face

-

^{5rnm fibre}

thickness Gss i 1

6 5 5 3

I

Shell

Pig. 1

-

Cerachrome f i b r e s from k i l n GSS 1 . a ) hot f a c e , b ) hot f a c e , c ) a s received.

C1-590 JOURNAL

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PHYSIQUE

Fig. 2

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S a f f i l f i b r e s . a ) k i l n RR 1 , 290 c y c l e s , b) k i l n RK 2, 1000-1100 cyc- l e s , c ) a s received.

F i g u r e s 2a-c show two samples of S a f f i l f i b r e s used f o r d i f f e r e n t numbers of f i r i n g c y c l e s a s w e l l a s S a f f i l f i b r e s a s r e c e i v e d . I t i s c l e a r l y seen how t h e number of f i r i n g s i n f l u e n c e t h e c r y s t a l l i z a t i o n course and how t h e c r y s t a l s grow l a r g e r and l a r g e r . The c r y s t a l l i t e s i z e i n S a f f i l f i b r e s a s received i s about 0.5 prn / 7 / . F i g u r e 2a s h o r s c r y s t a l l i t e s i z e s of more than 3 p n . The l i g h t pink c o l o u r of t h e f i b r e s h a s not been explained.

Fig. 3

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S a f f i l f i b r e s from a t u n n e l k i l n . a ) v i t h Znk1204 a t 970°c, b) no ZnA1204 a t 1070%.

S a f f i l f i b r e s were u s e d a s p a c k i n g s i n a t i l e i n s u l a t e d t u n n e l k i l n . Near t h e i n l e t o p e n i n g o f t h e k i l n , a t a t e m p e r a t u r e o f 95o0c, v a p o u r s from t h e g l a z e condensed on t h e f i b r e s and formed ZnA12G4. These f i b r e s have a d i f f e r e n t mic- r o s t r u c t u r e compared t o S a f f i l f i b r e s used a t h i g h e r t e m p e r a t u r e s . T r a c e s o f ZnA1204 was a l s o found a t a t e m p e r a t u r e o f 1010 O C b u t n o t h i n g a t 10700C.

F i g u r e 3 a shows f i b r e s v i t h Zn.41204 a t 9JOoC and f i g u r e 3b f i b r e s a t 10700C.

i i e a t - t r e a t m e n t o f h1207-Si.02 f i b r e s g i v e s c r i s t o b a l i t a and m u l l i t e a s t h e main c r y s t a l l i n e p h a s e s . The amount o f t h e trio p h a s e s depends on f i b r e c o m p o s i t i o n and t e m p e r a t u r a . The i n f l u e n c e o f t h e k i l n a t m o s p h e r e i s n o t s o o b v i o u s and f u r t h e r t e s t s a r e needed t o i n v e s t i g a t e i t s i n f l u e n c e . I n p o l y c r y s t a l l i n e S a f - f i l f i b r e s h e a t - t r e a t m e n t i n f l u e n c e s t h e c r y s t a l growth and m i c r o s t r u c t u r e . C r y s t a l l i t e s i z e s l a r g e r t h a n 3

v m

have been found. ZnO-vapours from t h e g l a z e condensed and r e a c t e d w i t h S a f f i l f i b r e s and formed Znk12C4 a t a t e m p e r a t u r e o f a b o u t 930 OC i n a t u n n e l k i l n . A t h i g h e r t e m p e r a t u r e s i t was a b s e n t .

The r e s u l t s , which have been p r e s e n t e d h e r e , x i 1 1 be f o l l o w e d up by c o l l e c t i o n and e x a m i n a t i o n o f new f i b r e s a m p l e s from t h e k i l n s i n a b o u t a y e a r . T h i s i s done i n o r d e r t o s t u d y t h e a g e i n g and t h e i n f l u e n c e o f f i r i n g c o n d i t i o n s on t h e f i b r e s . A f t e r f i b r e s a m p l e s have been examined o v e r a p e r i o d o f a c o u p l e o f y e s r s i t w i l l be e a s i e r t o draw c o n c l u s i o n s a b o u t t h e i n f l u e n c e o f t h e f i r i n g c o n d i t i o n s .

G r a t i t u d e s a r e e x p r e s s e d t o I% i i u s t a v s b e r g , Hiigangs AB and K o r s t r a n d AB f o r p r o v i d i n g f i b r e s a m p l e s . Wr. L. Eklund and I<s. C . P e t t e r s s o n a r e thanked f o r t h e h e l p w i t h SElvl examinations end irlrs. U-B. J i g h o l m f o r t y p i n g t h e manu- s c r i p t .

/ 1 / Gaodu, A . K . e t a l . , ideorg. Mater. 1 3 ( 1 9 7 7 ) 2265.

/2/ l i i r a k u s k i e t a l . , T a i k n b u t s u 25 (1973) 491.

/3/ H u p p e l t , K . , S i l i k a t t e c h n i k (1 983) 58.

/ 4 / K u t z e n d o r f e r , J. and Zbuzek, B., i b i d 33 ( 1 9 8 2 ) 535.

/5/ O l d s , L.X., M i l l e r , W.C. and P a l l o , J.PI: Am. Ceram. Soc. B u l l . j9 (1980) 739.

/6/ XXIVth international Colloquium on R e f r a c t o r i e s , Aachen 1981.

/7/ B i r c h a l l , J.i)., Trans. J. Br. Ceram. Soc. 82 (1983) 147.