the thermochemistry of transition metal carbides

7/25/2019 The Thermochemistry of Transition Metal Carbides

1/14

Oxida tion of Metals Vol . 13 N o. 2 197 9

T h e T h e r m o c h e m i s tr y o f T r a n s i t io n M e t a l a r b id e s

Stephen R. Shatynski

R e c e i v e d M a r c h 2 9 1 9 7 8 R e v i s e d M a y 18 1 9 7 8

A general survey is made of the available data for the standard Gibbs energies

of formation of solid carbides of transition metals . The results are plotted as

standard Gibbs energy vs. temperature diagrams. The equations and the

estimated accuracy when available are given for each substance.

KEY WORDS : standard Gibbs energy of formation; transition metal carbides; Ellingham

diagrams.

I N T R O D U C T I O N

A r e v i e w o f t h e e q u i l i b r i u m a n d t h e r m o d y n a m i c d a t a o f t h e t ra n s i t io n m e t a l

c a r b i d e s is p r e s e n t e d w i t h p a r t ic u l a r e m p h a s i s o n t h e G i b b s e n e r g y o f

f o r m a t i o n . T h i s w o r k r e v i e w s , u p d a t e s , a n d e x t e n d s t h e e a r l i e r s u r v e y s

p e r f o r m e d b y R i c h a r d s o n 1 a n d K u b a s c h e w s k i

et al., 2

a n d t h e m o r e r e c e n t

o n e s b y R e e d 3 a n d W i c k s a n d B l o c k . 4 M u c h o f R e e d s c o m p i l a t io n o f

c a r b id e t h e r m o c h e m i c a l d a t a w a s g a t h e r e d f r o m R i c h a r d s o n . 1 D a t a f o r th e

G i b b s e n e r g i e s o f f o r m a t i o n f o r c a r b id e s a s a f u n c t i o n o f t e m p e r a t u r e a r e

p r e s e n t e d a s E l l i n g h a m p l o t s a s s h o w n i n F i g s . 1 a n d 2 . I n t h i s p a p e r , t h e

G i b b s e n e r g i e s a r e n o r m a l i z e d w i t h r e s p e c t t o 1 m o l e o f C . T h e g e n e r a l

r e a c t i o n c o n s i d e r e d i s :

x M + C - ~ M x C

F o r t h e s e r e a c t i o n s t h e s t a n d a r d s t a t e s a r e a s f o l l o w s t : ( 1 ) f o r s o l id o r

l i q u i d m e t a l , a c o e x i s t e n c e w i t h i ts l o w e s t c a r b i d e , ( 2) f o r C , a so l i d o f u n i t

a c t i v i t y , a n d ( 3 ) f o r c a r b i d e s , t h e s o l i d a n d l i q u i d c a r b i d e i n c o e x i s t e n c e

Rensselaer Polytechnic Institute, Materials Engineering Department, Troy, New York

12181.

tM an y of the existing data are based on coexistence standard states, not pure standard states.

1 0 5

0030-770X/79/0400-0105503.00/0 @ 1979 PlenumPublishingCorporation


2/14

1 0 6 S h a t y n s k i

P c 2 o P c o 2 1 04 1 0 3 0 z I 0 I I0 I ( ~2

a b o v e 4 0 0 C ) / / / / l / /

1 ( )151 ( )J 01 (~6102 I l O I 0 2 ) 0 3 1 0 4 1 0 5 1 0 6

0 400 800 T (~ 1200 1600 2000

c c

I

I

I

I \

g M n r C 3

~ - ~ . . . I ~ C r 2 3C 6

/

I 0 6

J

) 0 5

1 0

i 0 3

C a r b o n

a c t i v i t y

0 3

1 I O

6 , ,

6 5 , 0 - )

0 - 6

1 0 - 2

o o 0 o o 0 2 ~

0 ~ ) l O - I 5 )d l 2 ] ) lO l ) 8 I ~ ~ l O 4 ) { )~ ) 0 2 I O l I

I

( a b o v e ' t O O ) C )

P ~ H ~

) 0 ) 2

I 0 I I I d IO I (~9

( a b o v e 4 0 0 C )

F i g . 1 . E l l i n g h a m d i a g r a m f o r t h e fi rs t t r a n s it io n s e r i e s c a r b i d e s . T h e

f o r m a t i o n o f t h e l o w e s t c o m p o u n d f o r m e d f r o m t h e m e t a l u p o n

r e a c t i o n w i t h 1 m o l e o f C i s d e n o t e d o n l y b y t h e c o m p o u n d M x C .

No t e : a l l G ibbs energ y v a lues a re repo r t ed in ca lo r ie s a nd a re

n o r m a l i z e d t o I m o l e o f c a r b o n a n d s i n c e m a n y o f t h e e x i s ti n g d a t a a re

ba se d o n co ex i s t en ce s t a nda rd s t a t e s , t he un i t a c t iv it y fo r t he m et a l i s

t he m et a l sa t ura t ed wi t h respec t t o t he ca rbide a nd l ikewise uni t

a c t iv i t y f o r t he ca rbide i s t he ca rbide sa t ura t ed wi t h i t s re spec t iv e

m et a l . )

e q u i l i b r iu m w i t h t h e o t h e r c o n d e n s e d p h a s e o f t h e r e a c ti o n . M a n y t r a n s i ti o n

m e t a l s fo r m se v e r a l c a r b id e s a n d a n e f fo r t i s m a d e t o r e p o r t t h e i r e x i s t e n c e

a n d s t a b il it ie s . E x a m i n a t i o n o f t h e a v a i l a b le p h a s e d i a g ra m s n o t e s t h e l a rg e

d e v i a t i o n f r o m s t o i c h i o m e t r y o f m a n y o f t h e t r a n s it i o n m e t a l c a r b i d es . A n


3/14

T h e T h e r m o c h e m i s t r y o f r a n s i t i o n M e t a l C a r b i d e s 1 0 7

~ c o / P c J o ~ io ~ i o i o , ~ a

0

~ f o e

I ~

1 6 s

I 3 - ]

z~c , o ~ ~ ~

- . . , ,

o 400 aoo T( C}~~176 leoo zooo

r c o / r c 0 2_ _ t I I t t t ; t , I k ,. ~ 6 a

*bore

4 o 0 c ) I d ~ s I 6' z ~ 6 J ~ ~ 6 4 ~ 6 ~ 1 6 1 6 I

o

~ d m ( 6 I 16 ~ o 1 6 9

o ~ o v e 4 0 0 C )

Fig.

2 Ellingham

d i a g r a m f o r t h e s e c o n d a n d t h i r d

transition

s e r i e s

c a r b i d e s . T h e f o r m a t i o n o f t h e l o w e s t c o m p o u n d f o r m e d f r o m t h e

m e t a l u p o n r e a c t i o n w i t h 1 m o l e o f C is d e n o t e d o n l y b y

the

c o m p o u n d

M~C.

orbon

a c t i v i t y

63. ~0

~ 4 . I

1(52

9 163

~ b 4

e f fo r t h a s b e e n m a d e t o n o t e t hi s d e v ia t io n f r o m s t o ic h i o m e t r y . G e n e r a l l y a

ca r bon de f ic i t is obs e r ved . T he i n f l uence o f t he no ns t o i ch i om e t r y upo n t he

t h e r m o c h e m i s t r y h a s n o t g e n e r a l l y b e e n e x a m i n e d .

T h e s t a n d a r d f r e e e n e r g y c h a n g e fo r e a c h re a c t i o n z kG~ i s r e la ted to

t h e s t a n d a r d e n t h a l p y c h a n g e A H ~ ) a n d t h e s t a n d a r d e n t r o p y c h a n g e A S~ )

by t he f o l low i ng equa t i on :

- - A H ~ - r a s ~


4/14

1 8 Shatynski

M a n y o f th e r e p o r t e d d a t a a p p e a r i n th is fo r m . S i n c e t h e c h a n g e i n e n t h a lp y

a n d e n t r o p y c a n b e e x p r e s s e d d i r e c t l y i n t e r m s o f h e a t c a p a c i t y a n d

t e m p e r a t u r e , a n e m p i r i ca l e q u a t i o n m a y b e w r i t te n f o r t h e s t a n d a r d f r e e

e n e r g y c h a n g e :

A G ~ = [ A H ~ 2 9 8 ) + I2 9T sA c p d T ] - T [ A S ~ 2 9 8 )

} 2 9T 8 C ~ z ]

S i n c e C ~ is n o r m a l l y e x p r e s s e d a s

C p = a + b T + c T - 2

t h e a b o v e e x p r e s s i o n c a n b e r e a d i ly i n t e g r a t e d t o y ie l d A G o a s a f u n c t i o n o f

t e m p e r a t u r e .

C R B I D E S O F T H E F IR S T T R N S I T I O N S E R IE S

T i t a n i u m

O n l y o n e c a r b i d e o f T i is k n o w n t o e x i st , 5-8 T i C ( m e l t in g p o i n t 3 3 4 0 ~

T I C is g e n e r a l l y c o n s i d e r e d t o h a v e a c o n s i d e r a b l e d e f ic it o f c a r b o n a n d

t h u s m a y v a r y c o n t i n u o u s l y f r o m T i l .s C t o T i C . R i c h a r d s o n a f ir st r e p o r t e d

t h e G i b b s e n e r g y o f f o r m a t i o n o f T i C c o r r e s p o n d i n g t o th e r e a c t i o n

T i + C ~ T i C

t o b e :

A G o ( T IC ) = - 4 3 , 7 5 0 + 2 . 4 1 T c a l / m o l e C ( + 3 0 0 0 c al) ,

in t h e t e m p e r a t u r e r a n g e 2 9 8 - 1 1 5 0 ~ A t h ig h e r t e m p e r a t u r e s ( 1 1 5 0 -

2 0 0 0 ~ R i c h a r d s o n 1 r e p o r t e d :

A G o ( T IC ) = - 4 4 , 6 0 0 + 3 . 1 6 T ( + 3 0 0 0 c al)

T h e s e e a r l y m e a s u r e m e n t s a r e f o u n d t o b e in g o o d a g r e e m e n t w i th m o r e

r e c e n t d a t a o f W i c k s a n d B l o c k 4 a n d K e l l e y a n d M a h . 1~ W i c k s a n d B l o c k 4

r e p o r t f o r t h e a b o v e r e a c t io n

A G ~ = - 4 5 , 1 0 0 - 2 . 4 8 T I n T + 1 .3 7 x 1 0 - 3 T 2 + 0 . 74 x 1 0 S T -1

+ 1 9 . 4 T

f o r t h e t e m p e r a t u r e r a n g e o f 2 9 8 - 1 1 5 0 ~ a n d

A G ~ (Ti.C ) = - 4 5 , 2 0 0 - 0 . 2 3 T I n T + 0 . 1 1 1 0 - 3 T 2 + 0 . 74 1 0 5 T -1

+ 4 . 9 6 T


5/14

Th e Thermochemistry of Transit ion Metal Carbides 1 9

for the temperatu re range 1150-1800~ Fujishiro and Gokcen , 11 using a

Knudsen cell equilibrium pressure measurement, have found the AG O TIC)

for the temperature range 2383-2593~ to be

AG o (TIC) = -1 41,064 + 35. 0T (=e2000 cal).

V a n a d i u m

Numerous carbides of vanadium have been reportedS 9 12: V2C (melting

point 2460~ V3C2 (stable below 1800~ V6C5, VsC7, and VC (melting

point 2921~ A large degree of nonstoichiometry is presen t in both V2C

and VC. Storms e t a l 1 2 report that VC exists between VC0 74and VCo.91 at

1700~ At the upper composition, the vacancies apparen tly ord er at

1403~ to give V8C7 and C. V2C in a similar manner extends from VCo.45 to

VCo.58 at 1700~ 12 Pillai and Sundaresan, ~3 using EMF techniques, have

measured AG~ to be

AG O V2C) = -41 ,9 70 + 21.26 x 10-3T cal/mole C ( 1800 cal)

for the reaction

2V +C-* V2C

within the temperat ure range 770-850~ These results are in good

agreement with the previous work of Worrell and Chipman 14 and Kireev

and Karape tyantes, ~s but not with the earlier work of Volkova and Oel d 16

and Alekseev and Shavartsman. ~7 Apparently difficulties due to mixed

vanadium carbides can account for the lack of agreement, which thus

discounts the earlier work. For the above react ion Worrell and Chipman 18

report

AG ~ (V2C) = -35 ,200 + 1.0 T cal /mo le C (+2000 cal)

for the tempera ture range 1200-1350~ For the reaction

V+C-->VC

Worrell and Chipman 14 repor t

AG O VC) = -24,100 + 1.5 T cal /mo le C (:t:850 cad

for the temperature range 1180-1370~ This result is in good agreement

with those reported by Wicks and Block, 4 while this work supercedes that

reported by Richardson. ~ Fujishiro 19 used a Knudsen cell to obtain high-

temperature data for the above reaction. For the tempera ture range 2350-

2550~ he reports

AG o (VC) = -2 3, 30 0 + 2.0 T

which is in good agreement with the results of Mah. 2~


6/14

110 hatynski

hromium

Three carbides of Cr have been reported9:Cr23C6 (melting point

1848~ Cr7C3 (melting point 2038~ and Cr3C2 (melting point 2083~

Kulkarni and Worrel121 have recently remeasured the reaction

~ C r + C --~ 1Cr23C6

and obtained

1 0

gAGt (Cr23C6) -- -12 ,833- 3.05 T cal/mole C ( cal)

for the temperature range of 1150-1300~ Although in disagreement with

the previous data reported by Wicks and Block4 and Richardson, t the

torsion effusion experiments per formed by Kulkarni and Worrell zl are

believed to be more reliable.

Kulkarni and Worrel121 also studied the reaction

7Cr23C6 + C --~ 23

Cr7C3

and obtained for the temperature range 1100-1720~

~ o ~ z ~

~Cr7C3) 7.41T (+400 cal)

~Cr23C6 =

-29,985

-

This is also in conflict with the previously reported data] 1,2,4 In addit ion, they

studiedzl the reaction

3Cr7C3 + C ~ 7Cr3C2

in the temperature range 1300-1500~ and obtained

0 3 7

Aaf (3Cr7C3 -* gCr3C2) = -9840 - 2.64T cal/mole (+400 cal).

These results are in good agreement with the previous results of Mabuchi

and Matsushita,22 Storms, 23 and Tanaka

e t a l . z 4

They are in fair agreement

with the previous results of KleykampY and Vintaikin26 and are in poor

agreement with the results of Kelley e t a l . 2 7 Gleiser, 28 Wicks and Block,4

and Richardson. 1 Again mixed carbides appear to account for the poor

agreement of earlier results.

Manganese

Numerous carbides of Mn have been reportedg 29:Mn23C6 (melting

point 123~ MnlsC4 (stability range 1123-1293~ Mn3C (stability range

1243-1323~ MnsCz (melting point 1360~ and MnTC3 (melting point

1423~ Moat tar and Anderson 29 have studied the reaction

~M n + C --) 1Mn23C6

and have determined ~AG~ for the temperature range 900-


7/14

T h e T h e r m o c h e m i s t r y o f T r a n s it io n M e t a l a r b i d es

111

l l00~

1

gAGf (Mn23C6) = -15,359 + 5.6T cal/mole C (+1200 ca1)

For the compound Mn15C4 there are no rep orted thermodynamic data. The

comp ound Mn3C has been extensively studied. Frad 3~ notes that Mn3C is

thermodynamica lly unstable below 1123~ Richardson 1 and Wicks and

Block4 report data for Mn3C for 298-1 010 and 1500~ respectively. For

the reaction

3Mn + C ~ Mn3C

Richardson 1reports AG O Mn3C) = - 3 3 3 0 - 0.26 T cal/mole C (4-3000 cal)

for the temperature range 298-1010~ This result is in good agreement

with the results of Wicks and Block. 4 Moat tar and Anderson 29 also have

studied the reaction

and have determined

900-1100~

~Mn + C ~ 89

the 89176 for the temperature range

1

~ Gf(MnsC2) = -10,780 + 3.2 T cal/mole C (+300 cal)

for the reaction

7Mn + C~IMn7C3

Moat tar and Anderson 29 obtained

89 G O Mn7C3) = - 10,130 + 3 T ca l/ mole C ( cal)

for the temperat ure range 900-1100~ This is in good agreement with the

previous results of McCabe and Hudson 31 but in poo r agreement with

Gokcen and Fujishiro. 32

r o n

Numerous carbides of Fe have been reported, ranging in composition

from FeaC to Fe2C. There are few data concerning most of the carbides

except for the great wealth of data available concerning Fe3C. It is generally

agreed upon that the compounds Fe4C, Fe3C (melting point 1500~ FesC2

(melting point greater than 503~ Fe7C3, Fe20C9, and Fe2C exist. Fe2C was

first suggested by Giud et al 33 Hagg 34 noted that above 498~ mixtures of

Fe2C and Fe3C were found, whereas above 673~ only Fe3C was noted.

Hultgren et aL 35 note that FezC can bett er be described as Fe20C9. For the

reaction

3Fe + C ~ Fe3C


8/14

2 Shatynski

W i c k s a n d B l o c k 4 r e p o r t f o r t h e t e m p e r a t u r e r a n g e o f 2 9 8 - 4 6 3 ~

A G ~ F e3 C ) = + 4 5 3 0 - 5 . 4 3 T In T + 1 .1 6 1 0 - 3 T 2 - 0 .4 0 x 10 S T -1

+ 3 1 . 9 8 T

f o r t h e t e m p e r a t u r e r a n g e 4 6 3 - 1 0 3 3 ~

AG~~ F e3 C ) = + 3 8 5 0 - 1 1 . 4 1 T In T + 9 . 6 6 1 0 - 3 T 2 - 0 . 40 1 0 5 T -1

+ 6 6 . 2 T

f o r t h e t e m p e r a t u r e r a n g e 1 0 3 3 - 1 1 7 9 ~

A G ~ F e3 C ) = 1 3 , 1 3 0 + 9 . 6 8 T I n T - 0 .9 9 1 0 - 3 T 2 - 1 . 0 5 1 0 S T -1

- 7 8 . 1 4 T


A G ~ F e3 C ) = - 1 0 0 0 - 7 . 0 0 T I n T + 3 .5 1 0 - 3 T 2 - 1 .0 5 1 0 5 T -1

+ 4 6 . 4 5 T


A G o F e 3 C ) = 7 3 4 0 - 1 1 . 95 T I n T + 5. 01 1 0 - 3 T 2 1 . 05 l0 s T 1

+ 7 4 . 6 2 T


A G ~ F e3 C ) = 2 1 , 7 0 0 + 4 . 4 T I n T + 0 .5 1 0 - 3 T 2 - 1 .0 5 lO S T - 1 - 4 7 . 4 8 T

w h i le f o r t h e t e m p e r a t u r e r a n g e 1 8 0 3 - 1 9 0 0 ~

A G ~ F e3 C) = 89 8 0 + 3 . 5 0 T In T + 0 . 5 1 x 1 0 - 3 T 2 - 1 . 0 5 1 0 5T - 1 - 3 3 . 8 T

H u l t g r e n e t a l 5 h a v e r e p o r t e d A G o F e a C ) = 3 7 3 c a l / m o l e C a t 6 0 0 ~

C o b a l t

T w o r a t h e r u n s ta b l e c a r b i d es o f C o h a v e b e e n r e p o r t e d , C o 2 C r a n g e o f

s t a b il i t y b e t w e e n 7 7 3 a n d 1 0 7 3 ~ a n d C o 3 C . R i c h a r d s o n 1 r e p o r t s f o r t h e

r e a c t i o n

2 C o + C - ~ C o 2 C

t h a t t h e f r e e e n e r g y o f f o r m a t i o n o f C o z C is

A G o C o 2 C ) = + 3 9 5 0 - 2 . 0 8 T c a l / m o l e C + 50 0 ca l)

f o r t h e t e m p e r a t u r e r a n g e 2 9 8 - 1 2 0 0 ~ W i c k s a n d B l o c k 4 n o t e

A G o C o 3 C ) = + 9 0 0 0 c a l / m o l e C a t 2 9 8 ~


9/14

The Therm ochemistry of Transition M etal Carbides 3

N i c k e l

O n e c a r b i d e o f N i h as b e e n r e p o r t e d , N i 3C . N i3 C h a s b e e n r e p o r t e d t o

b e u n s t a b l e e v e n u n d e r a p r e s s u r e o f 6 0 k b a r . 8 R i c h a r d s o n 1 h a d r e p o r t e d f o r

t h e r e a c t i o n

3 N i + C -~ N i3 C

A G o (N i3 C) = + 8 1 1 0 - 1 . 7 0 T c a l / m o l e C ( + 3 0 0 0 c al)

f o r t h e t e m p e r a t u r e r a n g e 2 9 8 - 1 0 0 0 0 K . T h i s is in g o o d a g r e e m e n t w i t h th e

r e s u lt s r e p o r t e d b y W i c k s a n d B l o c k . 4

C o p p e r

O n l y t h e e x p l o s i v e c ar b i d e

Cu C

h a s b e e n r e p o r t e d . 8

Z i n c

T h e c o m p o u n d ZnC h a s b e e n r e p o r t e d b u t n o f u r th e r w o r k h a s b e e n

r e p o r t e d . 8

C A R B I D E S O F T H E S E C O N D T R A N S I T I O N S E R I E S

Z i r c o n i u m

O n l y o n e c a r b i d e o f Z r h a s b e e n r e p o r t e d : Z r C 4'5 ( m e l t in g p o i n t

3 7 1 8 ~ K u b a s c h e w s k i e t a l 2 r e p o r t t h e A G o ( Z r C ) f o r t h e r e a c t i o n

Z r + C ~ Z r C

t o b e

A G o ( Z r C ) = - 4 4 , 1 0 0 + 2. 2 T c a l / m o l e C ( + 3 0 0 0 c al)

w i t hi n t h e t e m p e r a t u r e r a n g e 2 9 8 - 2 2 2 0 ~ T h e s e re s ul ts a r e in g o o d

a g r e e m e n t w i t h t h e l a t e r r es u l ts o f W i c k s a n d B l o c k 4 a t 2 9 8 ~ a n d P o l l o c k 36

a t 2 6 7 5 ~

N i o b i u m

T w o c a r b i d e s o f N b h a v e b e e n i d e n ti f ie d : N b 2 C ( m e l ti n g p o i n t

2 7 7 7 ~ 5'9 a n d N b C ( m e l t i n g p o i n t 3 8 8 1 ~ s'9 W o r r e l l a n d C h i p m a n 14 18

s tu d ie d t h e A G o o f b o t h N b z C a n d N b C . T h e y d e t e r m i n e d t h e A G ~

f o r t h e r e a c t i o n

N b + C ~ N b C


10/14

4 Shatynski

t o b e

A G o ( N b C ) = - 3 1 , 1 0 0 + 0 . 4 T c a l / m o l e ( + 6 0 0 c al)

f o r t h e t e m p e r a t u r e r a n g e 1 1 8 0 - 1 3 7 0 ~ T h e s e r e su l ts a r e in e x c e ll e n t

a g r e e m e n t w i t h th e d a t a o b t a i n e d b y P a n k r a t z e t a l 3 7 I n a s i m i l a r m a n n e r ,

W o r r e l l a n d C h i p m a n 14'18 m e a s u r e d t h e A G o ( N b2 C ) f o r t h e r e a c t i o n

2 N b + C ~ N b 2 C

t o b e

A G o ( N g2 C ) = - 4 6 , 0 0 0 + 1 .0 T c a l / m o l e C ( c al )


M o l y b d e n u m

T h e r e a p p e a r s t o b e s o m e c o n fl ic t c o n c e r n i n g th e n u m b e r a n d

c o m p o s i t io n o f m o l y b d e n u m c a rb i d es . G l e i s e r a n d C h i p m a n 38 r e p o r t

m e a s u r e m e n t s o n M o z C w h e r e t h e c o m p o s i t i o n v a r i es f r o m M 02.21C t o

M01 .98C . W a l l a c e e t a l 3 9 r e p o r t v a lu e s f o r M o C 6 a w h i c h is a p p r o x i m a t e l y

~ M o 3C a. R u d y , 5 i n hi s p h a s e d i a g r a m , i ll u s tr a te s o n l y t w o c o m p o u n d s , M o z C

a n d M o C l - x . S t o r m s , 23 h o w e v e r , n o t e s t h e f o r m a t i o n o f t h r e e c a r b i d e s ,

M o C ( m e l ti n g p o i n t 2 8 0 0 ~

o~ Mo3C2

m e l t i n g p o i n t 2 8 2 3 ~ a n d

MozC

( m e l ti n g p o i n t 2 9 7 8 ~ T h e a p p a r e n t d is c re p a n c ie s a r e m o s t p r o b a b l y

r e l a t e d t o t h e h i g h d e g r e e o f d e v i a t i o n f r o m s t o i c h i o m e t r y th a t i s e x h i b i t e d

in th e M o - C s y s te m . F o r t h e r e a c t io n

2 M o + C ~ M o 2 C

S o l b a k k e n a n d E m m e t t 4~ r e p o r t

A G o ( M o 2 C ) = - 1 2 , 0 3 0 - 1 . 4 4 T c a l / m o l e C ( + 1 0 0 0 c a l)

f o r t h e t e m p e r a t u r e r a n g e 6 0 0 - 9 0 0 ~ T h e s e r es u lt s a r e in g o o d a g r e e m e n t

w i t h t h e p r e v i o u s r e su l ts o f G l e i s e r a n d C h i p m a n , 38 w h o r e p o r t

A G o ( M o z C ) = - 1 1 , 7 1 0 - 1 . 8 3 T c a l / m o l e C ( + 1 0 0 0 c al )

f o r t h e t e m p e r a t u r e r a n g e 1 2 0 0 - 1 3 4 0 ~ T h e s e r es u lt s a r e a ls o in g o o d

a g r e e m e n t w i t h t h e v a p o r i z a t i o n s t u d i e s o f F r ie s . 41 T h e s t a n d a r d f r e e e n e r g y

o f f o r m a t i o n o f M o 3 C 2 a t 2 1 0 0 ~ w a s r e p o r t e d b y W a l la c e e t a l 3 9 t o b e

A G o (M o 3 C2 ) = - 2 6 0 0 c a l / m o l e C ( + 1 5 0 0 c al)

B r o w n i n g a n d E m m e t t 42 r e p o r t t h e A G O o f M o C a t 9 5 0 ~ t o b e A G O M o C ) =

- 3 2 1 1 c a l / m o l e o f C .


11/14

The Thermochemistry of Transition M etal Carbides 5

R u t h e n i u m

A eutectic phase diagram with no compound formation has been

reported. 8 Gingerich,43 however, has identified RuC as a gas phase

compound.

R h o d i u m


reported, s

P a l l a d i u m


reported. 8

S i l v e r

Sneed and Brasted 44 and Sidgewick45 report the existence of the highly

unstable Ag2Ca.

C a d m i u m

There is no reported compound formation in the Cd-C system.

C A R B I D E S O F T H E T H I R D T R A N S I T I O N S E R I E S

H a f n i u m

There is little information concerning the carbides of Hr. One carbide,

HfC (melting point 4201~ has been reported. 5-9

T a n t a l u m

Two carbides of Ta have been identified: TaC (meiting point 3603~

and TiC (melting point 4256~ Using the torsion-effusion technique,

Kulkarni and Worrel146 obtained for the reaction

2Ta + C --> Ta2C

AG O Ta2C) = -47 ,000 + 2.1 T cal/mole C ( cal)

for the temperature range 1740-1900~ Worrell and Chipman 14 18

obtained thermodynamic data for the reaction

Ta+C-~TaC


12/14

6 Shatynski

For the tempera ture range of 1250-1400~ they obtained

AG o TaC) = -34,900 + 0.5 T cal/mole C +600 cal).

This result is in good agreement with previous results of Pankratz e t a l 4 7 but

not with the reported values of Wicks and Block. 4

T u n g s t e n

Two compounds of W have been identified: W C melting point

3049~ and WC melting point 3049~ Gupta and Seigle48 have recently

reinvestigated the W- C system. For the reaction

2 W+C ~ W2 C

They obtained AG~ cal/mole C +100 cal) for the

temperature range 1150-1575~ These results are in good agreement with

previously reported data by Kubaschewski

e t a l . 2

but in poor agreement

with the data reported by Wicks and Block. 4

R h e n i u m

No carbide compounds have been reported. 8

O s m i u m

A eutectic system with the compound OsC has been reported, s No

further data are known.

Ir idium

There are no reported Ir compounds. 8

P l a t i n u m

There are no reported Pt carbides; a simple eutectic phase diagram has

been proposed. 8

G o l d

The highly explosive Au2C2 compound hasbeen reported. 45

Mercury

There are no reported Hg carbides. 8


13/14

Th e Thermochemistry of Transit ion Metal Carbides 117

R E F E R E N C E S

1 . F . D. Richardson , J. Iron SteelInst. 175, 33 (1953).

2 . O. Kubaschewsk i , E . L . Evans , and C. B. Alcock , Metallurgical Therrnochemistry

(Pergamon Press , Oxford, 1967).

3 . T . BL Re e d , Free Energy of Formation of Binary Compounds: An Atlas of Charts for High

Temperature Chemical Calculations (M.I .T . P ress , Cambr idge , Mass . , 197 t ) .

4 . C. E . Wicks and F . E . Block , Bur. Mines Bull. 605 (1973).

5 . E . Ru d y , T e r n a r y P h a s e E q u i l i b r i a i n T r a n s i t i o n M e ta l - Bo r o n , Ca r b o n , S i li c on S y s t e m s ,

P a r t V , C o m p e n d i u m o f P h a se D i a g r a m D a t a , A F M L - T R - 6 5 - 2 , W r i g h t - P at t er s o n A i r

Forc e Base , Oh io , (1967).

6 . M . H a n s e n ,

Constitution of Binary Alloys

( M c G r a w - H i l l , N e w Y o r k , 1 93 6) .

7 . R. P . Ell io t t , Constitution of Binary Alloys F i r s t S u p p l e m e n t ( M c G r a w - H i l l , N e w Y o r k ,

1965).

8 . F . A . Shunk ,

Constitution of Binary Alloys

S e c o n d S u p p l em e n t ( M c G r a w - H i l l, N e w Y o r k ,

1969).

9 . W. A. M offa t t , The Handbook of Binary Phase Diagrams ( G e n e r a l E l e c t r i c Co . , S c h e n e c -

tady, N.Y., 1976).

10 . K. K. Ke l ley and A . D. M ah , Bureau of Mines Report of Investigations Number 5 4 9 0

(1959).

11 . S . Fu j i sh i ro and N. A. G okce n , J . Phys. Chem. 65 161 (1961).

12 . E . K. S to rms , A. Lo we , E . Bacca , and J . Gr i f fin , High Temp. Sci. 5, 276 (1973).

13 . P . V. S . P i lla i and M. Su ndaresan , Trans. Ind. Inst. Met. 28, 319 (1975).

14 . W. L . Worre l l and J . Ch ipman , Z

Phys. Chem.

68, 860 (1964).

15 . T . K i reev and R. Karape tya n tes , J . Chem. Phys. 40, 68 (1966).

1 6. N . M . V o lk o v a a n d P . V . G e l ' d , lnz. Vyssikh. Zaved. Tsvem. Met. 77, 8 (1965).

1 7. V . I . A le k s e e v a n d L . V . S h a v a rt s m a n ,

Dokl. Akad. Nauk SSSR

113, 1327 (1960).

1 8. W . L , W o r r e l l a n d J. Ch ip m a n , Trans. Am. Inst. Min. Metall. Pet. Eng. 230, 1682 (1964).

19. S . Fujish iro , Trans. Jpn. Inst. Met. 35, 997 (1971).

2 0 . A . D . M a h , Bureau of Mines Report of Investigations Number 6177 (1963).

2 1 . A . D , K u lk a r n i a n d W . L . W o r r e l l,

Metall. Trans.

3, 2363 (1972).

22 . H. Mabu ch i and Y. M atsush i ta , Metall. Trans. 2, 1503 (1971).

23 . E . K. S to rms , The Refractory Carbides (Ac adem ic P ress , New York , 1967).

2 4 . H . T a n a k a , Y . K i s h id a , A . K a w a y u c h i , a n d J . M o r iy a m a , u n p u b l i s h e d r e s e a rc h , D e p a r t -

men t o f Meta l lu rgy , Kyo to Univers i ty , Japan (1970) .

2 5 . H . K le y k a m p , Bet. Bunsenges. Phys. Chem. 73, 354 (1969).

26 . Y. Z . Vin ta ik in , Fiz. Met. Metalloved. 16 144 (1963).

2 7 . K . K . K e l l ey , F . S . Bo e r i c k e , G . E . M o o r e , E . H . H u f f m a n , a n d W . M . Bo n g e r t , U .S .

Bureau o f Mines , Techn ica l Paper 662 (1944) .

28 . M. Gle ise r , J . Phys. Chem. 69, 1771 (1965).

2 9 . F . M o a t t a r a n d J . S. A n d e r s o n , Trans. Faraday Soc. 67, 2303 (1971).

3 0 . W . A . F r a d , Adv. Inorg. Chem. Radiochem. 11, 188 (1968).

3 1 . C . L . M c Ca b e a n d R . G . H u d s o n , Trans. Am. Inst. Min. Metall. Pet. Eng. 209, 17 (1957).

32 . N. A. G okc en and S. Fu j i sh i ro , Trans. Am. Inst. Min. Metall. Pet. Eng. 227, 542 (1963).

33 . W. Glud , K. V. Ot to , and H. Ri t te r ,

Ber. Ges. Kohlentech.

3, 40 (1929).

34 . G. Hagg , Z. Kristallogr. 89, 92 (1934).

3 5 . R . H u l tg r e n , R . L . O r r , P . D . A n d e r s o n , a n d K . K . K e l l e y , Selected Values of Ther-

modynamic Properties of Metals and Alloys (Wiley , Ne w Y ork , 1963).

36 . B. D. Po l lock , J . Phys. Chem. 65, 731 (1961).

37 . L . B. Pankra tz , W . W. W el le r , and K. K. Ke l ley ,

Bureau of Mines Report of Investigations

Number

6446 (1964).

38 . M. Gle ise r and J . Ch ip man , J .

Phys. Chem.

66, 1539 (1962).

39 . T . C. W al lace , G. P . Gu t ie r rez , and P . L . S tone , J . Phys. Chem. 67, 796 (1963).

4 0 . A . S o lb a k k e n a n d P . H . E m m e t t , J. Am. Chem. Soc. 91, 31 (1969).

41. R. J. Fries , 3 . Chem. Phys. 46, 4463 (1967).


14/14

8 Shatynski

4 2 . L . C . Br o w n in g a n d P. H . E m m e t t , J . Am. Chem. Soc. 74, 477 3 1952).

4 3 . K . A . G in g e r i c h , Chem. Phys. Len. 25 , 523 1974).

4 4 . M . C . S n e e d a n d R . C . Br a s t e d , Comprehensive Inorganic Chemistry Vo l . I I Va n

Nos t rand , P r ince ton , N.J . , 1954) .

45 . N. V. S idgewick , The Chemical Elements and Their Compounds Oxford Univ . P ress ,

Oxford, 1950).

4 6 . A . D . K u lk a r n i a n d W . L . W o r r e l l , Metall. Trans. 4, 931 1973).

47 . L . B. Pankra tz , W. W. Wel le r , and E . B. King , Bureau of Mines Report of Investigations

Number 6861 1966).

48 . D. K. Gup ta and L . L . Se ig le , Metall. Trans. 6A , 1939 1975).

the thermochemistry of transition metal carbides

Documents