Welcome to 3.091 Lecture 24

November 6, 2009

Diffusion

Ener

gy

Qv

Substitutional (vacancy)

Image by MIT OpenCourseWare. Adapted from Fig. 5-4 in Askeland, Donald R. The Science and Engineering of Materials. 2nd ed. Boston, MA: PWS-Kent, 1989. ISBN: 0534916570.

Act

ivat

ion

ener

gy (c

al/m

ol)

70,000 Q vs melting point 60,000

50,000 Ag

40,000 Au Al

30,000 Pb

20,000

10,000 200

Temperature (oC)

Fe

Cu

400 600 800 1000 1200 1400 1600

Image by MIT OpenCourseWare. Adapted from Fig. 5-8 in Askeland, Donald R. The Science and Engineering of Materials. 2nd ed. Boston, MA: PWS-Kent, 1989. ISBN: 0534916570.

Ener

gy

Qi

Interstitial

Image by MIT OpenCourseWare. Adapted from Fig. 5-4 in Askeland, Donald R. The Science and Engineering of Materials. 2nd ed. Boston, MA: PWS-Kent, 1989. ISBN: 0534916570.

Hot! Hot! 59Co 60Co 60Co59Co 59Co 59Co

Courtesy of The Minerals, Metals, and Materials Society. Used with permission.

10 3

10_4

10_5

10_6

10_7

10_8

10_9

10_10

10_11

10_12

10_13

10_14

10_15

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3

Diff

usio

n co

effic

ient

(cm

2 /s)

H in BCC ironH in FCC iron

C in FCC iron C in BCC iron

Fe in FeO

Fe in BCC iron

Fe in FCC iron

Ca in CaO

Mg in M

gO

C in graphite

Temperature (oC) 2000 1500 1200 1000 900 800 700 600 500 _

1000 T(K)

Image by MIT OpenCourseWare. Adapted from Fig. 5-7 in Askeland, Donald R. The Science and Engineering of Materials. 2nd ed. Boston, MA: PWS-Kent, 1989. ISBN: 0534916570.

bulk

grain boundary

surface

Courtesy of John Wiley & Sons. Used with permission.

lattice or bulk

Courtesy of John Wiley & Sons. Used with permission.

log10D

surface

grain boundary

lattice or bulk

Courtesy of John Wiley & Sons. Used with permission.1/T

diffusion in molten

ferrous alloys

Courtesy of The Minerals, Metals, and Materials Society. Used with permission.

helium ingress into various oxide glasses

Tighter Packing

Courtesy of John Wiley & Sons. Used with permission.

723072407070

7900

7160SiO2

SiO2 + B2O3 + P2O5 (mole %)

7740772070407050

7056

7052

0010901081600080

0120

1715

17201723

K, P

erm

eatio

n ra

te

60 70 80 90 100

T = 300 oC

10_8

10_9

10_10

10_11

10_12

helium ingress intovarious oxide glasses

Courtesy of John Wiley & Sons. Used with permission.

Courtesy of John Wiley & Sons. Used with permission.

100

80

60

40

20

0 13:1 14:1 15:1

Con

vers

ion

effic

ienc

y (%

)

A/F ratio

NO CO HC

Window

Image by MIT OpenCourseWare.

Exhaust oxygen sensor

Catalytic converter (dual-bed pellet type)

Electronic control module

Electromechanical carburetor

Air pump

Image by MIT OpenCourseWare.

How an Oxygen Sensor Works

* faster diffusion of oxygen shorter response time

cold start issues!

Exhaust oxygen sensor

Catalytic converter (dual-bed pellet type)

Electronic control module

Electromechanical carburetor

Air pump

Semiconductors

Diffusion, Defects

Catalysis, Ceramics

Image by MIT OpenCourseWare.

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3.091SC Introduction to Solid State Chemistry Fall 2009

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