Pure materials of AIN, alpha-Si3N4 and TiC, without additives were sintered at 800 C to 1400 C under the pressures of 30 kbar and 50 kbar for 0.5 hours. The maximum density of sintered bodies for the cited materials was nearly 100% for AIN, 98% for TiC and 96% for alpha-Si3N4

Koizumi, M.

Ogawa, N.

Shimado, M.

English

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NASA TECHNICAL MEMORANDUM 
0 
NASA TM 75744 
H I G H  PRESSURE SINTERING OF NON-OXTDE MPTERTALS 
Masahiko Shimado, Noriyuki  Ogawa, and MitsueKoizurni 
(NASA-*TM-35744) HIGH PRESSURE SIRTEII.ING OE N80-2149 1 
U O N - O X I D E  MATEElALS (Nat ional  Aeronautics 
a!: S p a c e  A d m i n i s k r a t i o n )  7 F HC A02/HE A01 
CSCL 11F UncLas 
G3/26 46854 
T r a n s l a t i o n  o f  tlHikinzoku No Koat s u  Kes shot ' ,  
J .  o f  Japan S o c i e t y  of Powder and Powder 
Meta l lu rgy ,  v o l .  25, no. 8 ,  Dec., 1978, pp, 
275-276. 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON, D. C. 20546 NOVEMBER 197 9 
i STANDARD T ITLE  PAGE 'i 
1. R ~ p a r t  Nu. 2. Covmrnmmnt Accer r ron  No. 3: Hmcipient'r C o t o l o ~  No. 
, NASA TM- 75744 
1. T I I I ~  and Subtrtlm 5. Ueport.Dote 
November 1979 HIGH PRESSURE SINTERING OF. NON-OXIDE MATERIALS 
P~lfolminQ OIQ~nilol,an Cede 
I i I 
7. Author(*) 
I 
8. Performing Orgonrrut ion Rmport No. 
Masahiko Shimada, N0riyuk.i Ogawa, Mitsue Koizumi, 
10. Work Un i t  No. 
9. Periorm:ng O r s o n ~ i a t t o n  Name and Addrars 11. Controct or Gront No. 
' . S C I T R A S  :(AS>!- 319 8 
SOX 5 4 %  13. Yypm o l  Rsporr ond Pmriod Covermd 
S=,:l:a Sarbarri  , C.4 93108 T r a n s l a  t i o n  
12. Sponrot~ng Agency Noma and Addtmvr' 
S;:ion-: A s r c n a u r i c s  2nd S p a c e  
Sson,efing AQmncy I \ 'oshingcon,  D.C. 20546 
Translation 0.f "~ ik inzoku  No Koatsu Kesshotl, 
J. of Japan Society of Powder and Powder 
/ Metallurgy, vol. 25, no. 8,  Dec., 1978, pp, 
275-276. 
High pkessure s i n t e r i n g  of pure mater ia ls  of A I N ,  a-Si N and TIC, I 3 4 without addi t ives ,  was ca r r i ed  out at 8 0 0 - 1 4 0 0 ~ ~  under t h e  i r e ssures  
of 30 kbar and 50 kbar f o r  0.5 hours. The maxi* densi ty of sin- 
t e red  bodies f o r  t h e ,  c i t e d  mater ia ls  was n e a ~ l y  100% f o r  A I N ,  98% ! 
. fo r  T i c  and 96% forW3i3Nq. 9 re f s .  I n  Japanese. 
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3 
High Pressure Slntering of Non-Oxide Mater$,als** 
Masahiko Shimada***, Noriyuki Ogawa*", and Mltsue Roizumi** 
High pressure sintering of pure materials of ATN, a- Si3N4 
and TIC without additives was carried out at 800-1400~~ under the 
pressures of 30 kbar and 50 kbar for'0.5 hr. The maxtrnum density 
of sintered bodies for the above materials was nearly 100% for AIN, 
98% for Tic and 96% for a-S13N4. 
1. Introduction 
- -
One of the characteristics of ceramic materials is their high 
heat resistance. This feature was discovered particularly in re- 
f * cent years. Many attempts have been made to use non-oxide ceramic 
I .  
P ! materials such as Si3N4, Sic and ATN as high temperature, high 
r C :  stress, structural materials which replace metals in the high 
; 'i temperature range beyond the limit of their heat resistivity. How- 
:; ever, non-oxide materials which are excellent high temperature, 
high stress, structural materials generally have strong covalent 
bonds and the rates of the self-diffusion of the computers are very 
small. Consequently, they are not easily sintered compared to the 
i 1 case of oxides. Therefore, in order to increase the density of i " 
sintered bodies, the hot press method is usually applied to make 1 i dense ceramics. In this method, appropriate additives are added 
to the materials. As additives for sintering S13N4, ~g0"' and 
. 
~ ~ 0 ~ ' ~ ' ~ '  are well known. For AIN, Y 0 
L 2 3 '41 is used. Metals such 
as iron and aluminum C51 and B4C and A1 0 2 3 '61 and a mixture of 
: b 
boron and carbonC7] are used as good additives for sintering the 
1 :  SIC ceramics. However, the additives used for making denser mat- 
I 
c erials are often reduced as the second phase, such as s glass layer 
1 at the boundary of sintered bodies. Consequently, mechanical prop- 
* Numbers in margins indicate foreign pagination, 
**Reported in the spring meeting of the present society in May, 
1978. 
*** The rndustrial Science Research Institute, Osaka University, 
Zip Code 565, Yamada-he, Suita-shi. 
.-: --- - 
- .--*--.- * .. - L - . I IC-- 
\ 
e r t i e s  of  t h e  m a t e r i a l s  
C31 e r a t u r e  range . 
a r e  weakened s i g n i f i c a n t l y  i n  t h e  h igh  temp-. 
d 
Therefore ,  i n  o r d e r  t o  o b t a i n  non-oxtde ceramics  which pos se s s  
good mechanical  p r o p e r t i e s  a t  h igh  t empera tu res ,  i t  Is necessa ry  
t o  o b t a i n  s i n t e r e d  bodfes  o f  h igh  p u r i t y  and h igh  d e n s i t y  having a 
t h e o r e t i c a l  d e n s i t y  wi thou t  u s i n g  t h e s e  addlCfves. For t h i s  pur- 
pose, we have been exper iment ing i n  s i n t e r i n g  non-oxide m a t e r i a l s  
such as ca rb ides  and n i t r i d e s  of  h igh  p u r i t y  and h igh  d e n s i t y  by 
u s i n g  a high p r e s s u r e  s i n t e r i n g  method wi thou t  u s i n g  a d d i t i v e s .  
These m a t e r i a l s  a r e  be l i eved  t o  be d i f f i c u l t  t o  s i n t e r .  En t h e  
p r e s e n t  r e p o r t ,  we p r e s e n t  t h e  summary of  OUT s tudy.  
2 .  Tes t  samples and t h e  exper imenta l  procedure .  
The raw m a t e r i a l s  used f o r  t h e  h igh  pressupe s i n t e ~ i n g  exper- 
iment a r e  ATN made by Nippon Denko Co., a-Si N made by t h e  S t a r k  3 4 
Co. and T i c  made by Keunametal Co. T h e i r  characteristics a r e  shown 
i n  Table  1. 
The h ~ g :  p r e s s u r e  c e l l  used i n  h igh  p r e s s u r e  s i n t e r i n g  i s  a 
r e g u l a r  hexagonal h i g h  p r e s s u r e  c e l l  (DTA-15) which has  an  a u b i l l  
of l5mm. A s  i s  shown i n  F igu re  1, p y r o p h y l i t e  was used f o r  t h e  
p r e s s i n g  m a t e r i a l s ,  and h e a t i n g  was done by e l e c t r i c  c u r r e n t s  i n  a 
g r a p h l t e  h e a t e r .  The t empera tu re  was measured by a thermocouple 
p laced  i n s i d e  t h e  c e l l .  F i r s t ,  t h e  p r e s s u r e  o f  t h e  sample room 
i n  t h e  c e l l  was measured by u s i n g  t h e  Bi 1-33 t r a n s i t i o n  a t  25.5 
k bars and B a  1-11 t r a n s i t i o n  a t  55 kba r s  a t  room tempera tu re .  
These B i  and Ba  a r e  t h e  p r e s s u r e  d e t e c t o r s .  The h igh  p r e s su re  s i n -  
t e r i n g  experiment was c a r r i e d  ou t  f o r  30 minutes a t  t empera tu res  
of ~ O O ~ C - ~ ~ O O ~ C  and p r e s s u r e s  of 30 kbar  and 50 kbars .  The dens i -  
t i e s  of  s i n t e r e d  bod ies  were measured by  t h e  Archimedes mesthod. 
The (values a r e  shown i n  Table 1 as t h e  r e l a t i v e  d e n s i t i e s  u s i n g  
t h e  t h e o r e t f c a l  d e n s i t y  v a l u e s .  Also, we found t h e  v a l u e s  T/T, , 
where T i s  t h e  s i n t e r i n g  t empera tu re  and T, i s  t h e  m e l t i n g  p o i n t  
Figure 1. Diagram of high pressure cell assembly used for high 
pressure sinterlng. 
shown in Table 1, and analyzed their values with respect to the 
relative density. /28  
< 
! 
Table 1 Characteristics of the pure materials 
1 Cryst;tl 'l'I~c~rt:~~r:itI MVIIIIII: or
I ~tructure density / dis\nci;ttiun 
- - -.- - , - 
-- - - 
(~ lcrn ' )  -, point* ("CJ 
3. Experimental results .and dfscussions 
Figure 2 shows t"i case when AIN, a-Sl N and TIC were high 3 4 
pressure-sintered at 30 kbars and 50 kbars wtthout using additives. 
6 
The horizontal axis T/Tm in Figure 2 represents the calculated 
values explained in the section for the experimental procedure. 
The sintering temperature was normalized by using the melting point 
which is characteristic of each material. This variable was used 
to compare the effects of pressure and temperature on increasing 
densities of various materials. 
As shown in Table 1, ATN has 96% purity. Therefore, because 
ORIGINAL PAGE IS 
OF POOR QUALITY 3 
F i g u r e  2.  DensLf lca t ion  of pure  m a t e r i a l s  under h i g h  temperature-  
p r e s s u r e s .  
of  e f f e c t s  o f  t h e  i r n p u ~ i t i e s ,  we ob t a ined  t h e  s l n t e r e d  body hayinq 
a  t h e o r e t i c a l  d e n s i t y .  However, when a-S13N4 of h i g h e r  p u r l t y  
were used, t h e  d e n s i t y  o f  t h e  former cou ld  n o t  i n c r e a s e  beyond 96% 
of t h e  t h e o r e t i c a l  v a l u e s  and t h e  l a t t e r  98% of t h e  theoretical 
va lue ,  i n  s p l t e  of t h e  h igh  ppessure  o f  50 kba r s  and t h e  s i n t e r i n g  
t empera tu re  o f  1400°C. The p r e s s u r e  had a  smal l  e f f e c t  on t h e  
d e n s i t i e s  o f  bo th  m a t e r i a l s .  However, t h e  t empera tu re  had almost  
no e f f e c t  i n  t h e  c a s e  o f  a-SL3N4. Th i s  i s  probably  due t o  t h e  small 
s e l f - d i f f u s i o n  r a t e  o f  n i t r o g e n  i n  a-Si N as r e p o r t e d  by Kizima, 
e t  a l ,  
3  4 C81 Also t h e  r a t e  does  no t  i n c r e a s e  s i g n i f i c a n t l y  w i th  temp- 
e r a t u r e ,  i n  c o n t r a s t  t o  t h e  c a s e  o f  ox ides .  There fore ,  i n  o r d e r  t o  
o b t a i n  s i n t e r e d  bod t e s  o f  t h e  S i  N ceramics  having t h e  t h e o r e t l -  3 4 
c a l  d e n s i t i e s  wi thou t  a d d i t i v e s .  We must e i t h e r  s i n t e r  (3-S& N 3 4 
which has  a  l a r g e  n i t r o g e n  s e l f - d i f f u s i o n  r a t e  a t  a h$gh t e m p e ~ a -  
t u r e  and a h t g h  p r e s s u r e ,  o r  u se  n o n - c r y s t a l l i n e  SB N a s  t h e  3  4 
s t a r t i n g  m a t e r i a l  and s i n t e p  it a t  a h i g h  p r e s s u r e  and a  h lgh  temp- 
. .. - 
e r a t u r e ,  w;t,th s imul taneous  c r y s t a l l i z a t i o n .  
F b 
b On t h e  o t h e r  hand, t h e  t empera tu re  had a  l a r g e  e f f e c t  on In-  
L c r e a s i n g  t h e  d e n s i t y .  Th i s  i s  i n  c o n t r a s t  t o  t h e  c a s e s  o f  T IC  and 
i ,  
i a-Si3N4. A t  50 kbar  p r e s s u r e  w e  cou ld  o b t a i n  s l n t e r e d  bod ies  o f  
: 
4 
" - 
. " 
- " * - .  * -.... =- *-- - ? 7 .  
r--4CYulLM - i.--IL---&- L d .-- t .. . . A . . C  
t h e o r e t l c a l  d e n s i t y  a t  th.e v a l u e s  o f  T/T, o f  ~ 0 . 5 ,  For  t h e  same 
c a r b i d e  S i c ,  Nadeau C93 c a r r i e d  o u t  h i g h  p r e s s u r e  s l n t e r i n g  expe r t -  
mentv wi thout  u s i n g  a d d i t i v e s .  He found t h a t  t h e  d e n s i t y  could  
r e a c h  almost  t h e  t r u e  s p e c i f i c  weight  a t  800°C, and above 1500°C, 
s i n t e r e d  bod i e s  o f  se l f -bonding were ob ta lned .  Concerning non- 
ox ide  ceramic m a t e r i a l s ,  t h e r e  a r e  few exper imenta l  r e p o r t s  which 
used t h e  u s u a l  ho t  p r e s s  method o r  t h e  h i g h  p r e s s u r e  s l n t e r i n g  
method withou* u s i n g  a d d i t i v e s .  There fore ,  we can n o t  compare 
and examine e f f e c t s  o f  p rese l l r e  and t empera tu re  and a l s o  e f f e c t s  
of  p a r t i c l e  s i z e  of  t h e  i n i t i a l  m a t e r i a l ;  on t h e  s i n t e r  r e a c t i o n .  
We i n t e n d  t o  t r y  t h e  h igh  p r e s s u r e  s i n t e ~ i n g  method on many non- 
ox ide  m a t e r i a l s  i n  t h e  f u t u r e ,  and examine e ' f f e c t s  o f  t empera tu re ,  
p r e s s u r e ,  t ime ,  t h e  g r a n u l a r  s i z e  o f  i n i t i a l  m a t e r i a l s  and d i f f e r -  
ence  of c r y s t a l  phase on t h e  d e n s i t y .  We a l s o  Pntend t o  observe  
t h e  f i n e  s t r u c t u r e s  o f  s i n t e r e d  bod ies  and t h e  ha rdness  i n  t h e  
h i g h  temperature  range  i n  o r d e r  t o  c l a r i f y  t h e  s i n t e r i n g  mechanism 
of non-oxide m a t e r i a l s  which a r e  normal ly  v e r y  d i f f i c u l t  t o  s i n t e r .  
1. 3.  G. Deeley, J .  M. Herver t  and N, C ,  Moor: Powde~  Met., 8  
(1961),  145. 
2 .  G .  E.  Gazza: J. Amer. Ceram. Soc. ,  56 (19731, 662. 
3.  Tsuge, Yoneya, Hashimoto, Nishida ,  T s i i ,  Toshtba Review 30 
(1975) 580. 
4 .  K. Komeya and H. Inoue:  Trans.  J, B r i t .  Ceram. Soc , ,  70  (1971) 
107. 
5. R. A.  A l l i e g r o ,  L. B.  Co f f i n  and J .  R.  Tinklepaugh: J ,  Amer, 
Ceram. Soc., 39 (19561, 386. 
6. J .  M. Bind and 3. Y. Biggers :  J .  Appl. Phys., 47 (1976) ,  517. 
7. S. Prochazka and R ,  M .  S can1an : ' J .  Amer. Ceram. Soc.,  58 (1975) 
72. 
8. R. Kizima and S. S h i r a s a k i :  J .  Phys. Chem. 65 (1976) 2668, 
9. J. S.  Nadeau: Amer. Ceram. Soc. Bu l l . ,  52(1973), 170. 
I . .  


High pressure sintering of non-oxide materials

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