Upcoming SlideShare
×

# Initial Sintering Mechanism of Mesocarbon Microbeads

1,520 views

Published on

Initial Sintering Mechanism of Mesocarbon Microbeads

0 Likes
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
• Be the first to comment

• Be the first to like this

Views
Total views
1,520
On SlideShare
0
From Embeds
0
Number of Embeds
31
Actions
Shares
0
0
0
Likes
0
Embeds 0
No embeds

No notes for slide

### Initial Sintering Mechanism of Mesocarbon Microbeads

1. 1. Initial Sintering Mechanism of Mesocarbon Microbeads Christopher W. Norfolk Alexander S. Mukasyan, Daniel E. E. Hayes, Paul J. McGinn, and Arvind Varma Sintering ‘03 July 25th, 2003
2. 2. Motivation
3. 3. Structure 5 µm
4. 4. Morphology 2 µm 10 µm
5. 5. Morphology Sintering Sintering Necks Necks 10 µm 1 µm 2 µm
6. 6. Final Density Characteristics 1.7 1.9 1.6 Curve 1 1.5 3 Final Density ρf, g/cm Density Ratio ρf/ρo 1.8 1.4 1.7 1.3 Curve 2 1.2 1.6 1.1 1.5 1.0 1.15 1.20 1.25 1.30 1.35 1.40 1.45 3 Initial Density ρo, g/cm
7. 7. Shrinkage Dynamics 0.12 Experimental Curve Least Squares Polynomial Fit 0.10 Dimensionless Shrinkage, λ 0.08 0.06 0.04 0.02 0.00 -0.02 400 600 800 1000 1200 1400 1600 1800 Temperature, K
8. 8. Shrinkage Rate 3.00 I II III IV V VI 4 Shrinkage Rate, dλ/dT, X10 2.00 1.00 0.00 -1.00 T1 T2 T3 T4 T5 400 600 800 1000 1200 1400 Temperature, K
9. 9. Activation Energy Analysis ∆L  x  n 2  x Bt λ= =    = m r r r Lo  2r  −Q B = B oT e a RT x T = To + β t d (ln λ ) 2(a + 1) 2Q 1 = + ⋅ d (lnT ) n Rn T
10. 10. Activation Energy Analysis 140 VI V IV 3 120 Curve 2 2 100 dλ/dT, X10 d lnλ/d lnT 80 1 60 4 0 40 Curve 1 20 -1 0 8 10 12 14 16 4 1/T, X10
11. 11. Summary !Is an activation energy approaching zero a reasonable result for a densifying sintering mechanism?
12. 12. Evolution of ρpyc 2.0 2.0 3 3 Pycnometric density ρ , g/cm 1.9 1.9 stage 2 stage 3 pyc pyc 1.8 1.8 1.7 1.7 1.6 1.6 stage 1 1.5 1.5 1.4 1.4 400 400 600 600 800 800 1000 1000 1200 1200 1400 1400 1600 1600 1800 1800 Temperature, K
13. 13. Relative Density Results pyc 1.00 0.95 Final relative density, ρf /ρf 0.90 0.85 0.80 0.80 0.85 0.90 0.95 1.00 pyc Initial relative density, ρo/ρo
14. 14. A Simple Example ρoth=3Mo/4πro3 ro rf Heat Lo Lf Treatment ro rf ρo=Mo/2πro3 ρoth=3Mo/4πro3 ρo=Mo/2πro3 ρfth=3Mf/4πrf3 ρf=Mf/2πrf3 ρf/ρo= ρfth/ρoth=(Mf/Mo)(ro/rf)3
15. 15. Thermogravimetric Analysis 100 0.0 Mass Percent Remaining, W 98 -0.5 96 dW/dT, X 10 94 -1.0 92 -1.5 2 90 -2.0 88 86 -2.5 200 400 600 800 1000 1200 1400 1600 1800 Temperature, K
16. 16. Thermogravimetric Analysis 6 0 -2 Mass #16 (Ion Current X 10 ) 11 5 -4 dW/dT X 10 4 -6 3 2 -8 2 -10 1 -12 200 400 600 800 1000 1200 1400 1600 1800 Temperature, K
17. 17. Thermogravimetric Analysis 3 0.0 -0.5 2 dW/dT X 10 4 dλ/dT X 10 -1.0 1 -1.5 2 0 -2.0 -1 -2.5 200 400 600 800 1000 1200 1400 1600 1800 Temperature, K
18. 18. Titanium Carbide 6 4 Shrinkage, Adjusted for Mass, λ Dimensionless Shrinkage, λ 2 50 wt % 0 -2 23 vol % -4 -6 Increasing TiC -8 -10 Content -12 -14 200 400 600 800 1000 1200 1400 1600 1600 1800 1800 Temperature, K
19. 19. Heating Schedule 1100 2 0.01 1000 900 0 0.00 Dimensionless Shrinkage, λ Shrinkage Rate, dλ/dt 800 Temperature, K -0.01 700 -2 600 -0.02 500 -4 -0.03 400 300 -0.04 200 -6 0 200 400 600 800 1000 1200 Time, min
20. 20. Heating Schedule 1800 2 0.01 1600 0 0.00 Dimensionless Shrinkage, λ 1400 -2 Shrinkage Rate, dλ/dt Temperature, K 1200 -0.01 -4 1000 -6 -0.02 800 -8 600 -0.03 400 -10 -0.04 200 -12 0 500 1000 1500 2000 Time, min
21. 21. Conclusions ! The main role of the β-resin is to maintain particle cohesion ! Sample shrinkage due primarily to increasing theoretical density, caused by crystallographic transformation ! Sample porosity remains largely unaffected by the sintering process