Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-11-25T04:24:31.290Z Has data issue: false hasContentIssue false
  • English
  • Français

Modeling the effect of gas transport on the formation of defects during thermolysis of powder moldings

Published online by Cambridge University Press:  31 January 2011

J. H. Song ,
M. J. Edirisinghe ,
J. R. G. Evans  and
E. H. Twizell
J. H. Song
Affiliation:
Department of Materials Technology, Brunel University, Uxbridge, Middlesex, UB8 3PH, United Kingdom
M. J. Edirisinghe
Affiliation:
Department of Materials Technology, Brunel University, Uxbridge, Middlesex, UB8 3PH, United Kingdom
J. R. G. Evans
Affiliation:
Department of Materials Technology, Brunel University, Uxbridge, Middlesex, UB8 3PH, United Kingdom
E. H. Twizell
Affiliation:
Department of Mathematics and Statistics, Brunel University, Uxbridge, Middlesex, UB8 3PH, United Kingdom
Get access

Abstract

The removal of binder from ceramic or metal moldings by thermolysis involves the transport of degradation products through the parent organic phase and the vacated porous body. A numerical model has been developed to combine an equation which takes into account different gas-flow regimes with an equation for the transport of organic molecules in molten polymers. Computer modeling reveals the critical heating rate above which defects occur due to boiling of the polymer-monomer solution at the center of the molding. The situation in which a porous outer layer of the molding develops, offering resistance to flow of the evolved monomer gas, is then treated. This gives rise to a moving boundary with a variable concentration of diffusant which is dependent on the surface flux, gas transport coefficient, and thickness of the porous layer. The contributions of diffusion and viscous flow to gas transport are considered.

Type
Articles
Information
Journal of Materials Research , Volume 11 , Issue 4 , April 1996 , pp. 830 - 840
Copyright
Copyright © Materials Research Society 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1.Edirisinghe, M. J. and Evans, J. R. G., Int. J. High Tech. Ceram. 2, 1, 249 (1986).CrossRefGoogle Scholar
2.Haunton, K. M., Wright, J. K., and Evans, J. R. G., Br. Ceram. Trans. J. 89, 33 (1990).Google Scholar
3.Hammond, P. and Evans, J. R. G., J. Mater. Sci. Lett. 10, 294 (1991).CrossRefGoogle Scholar
4.Greener, J. and Evans, J. R. G., J. Mater. Sci. 28, 6190 (1993).CrossRefGoogle Scholar
5.German, R. M., Hens, K. F., and Lin, S. T. P., Bull. Am. Ceram. Soc. 70, 1294 (1991).Google Scholar
6.German, R. M., Powder Injection Moulding (Metal Powder Industries Fed., NJ, 1990).Google Scholar
7.Calvert, P. and Cima, M., J. Am. Ceram. Soc. 73, 575 (1990).CrossRefGoogle Scholar
8.Evans, J. R. G., Edirisinghe, M. J., Wright, J. K., and Crank, J., Proc. R. Soc. London A 432, 321 (1991).Google Scholar
9.Matar, S. A., Edirisinghe, M. J., Evans, J. R. G., and Twizell, E. H., J. Mater. Res. 8, 617 (1993).CrossRefGoogle Scholar
10.Shaw, H. M. and Edirisinghe, M. J., Philos. Mag. A72, 267 (1995).CrossRefGoogle Scholar
11.Matar, S. A., Edirisinghe, M. J., Evans, J. R. G., Twizell, E. H., and Song, J. H., J. Mater. Sci. 30, 2805 (1995).CrossRefGoogle Scholar
12.Barone, M. and Ulicny, J. C., J. Am. Ceram. Soc. 72, 3323 (1990).CrossRefGoogle Scholar
13.Cima, M. J., Lewis, J. A., and Devoe, A., J. Am. Ceram. Soc. 72, 1192 (1989).CrossRefGoogle Scholar
14.German, R., Int. J. Powder Met. 23, 237 (1987).Google Scholar
15.Stangle, G. C. and Aksay, I. A., Chem. Eng. Sci. 45, 1719 (1990).CrossRefGoogle Scholar
16.Tsai, D-S., A.I.Ch.E.J. 37, 547 (1991).CrossRefGoogle Scholar
17.Angermann, H. H., Yang, F. K., and Van der Biest, O., J. Mater. Sci. 27, 2534 (1992).CrossRefGoogle Scholar
18.Angermann, H. H. and Van der Biest, O., Int. J. Powder Met. 29, 239 (1993).Google Scholar
19.Wakao, N., Otani, S., and Smith, J. M., A.I.Ch.E.J. 11, 435 (1965).CrossRefGoogle Scholar
20.Lewis, J. A. and Cima, M. J., J. Am. Ceram. Soc. 73, 2702 (1990).CrossRefGoogle Scholar
21.Sproson, D. W. and Messing, G. L., in Better Ceramics Through Chemistry III, edited by Brinker, C. J., Clark, D. E., and Ulrich, D. R. (Mater. Res. Soc. Symp. Proc. 121, Pittsburgh, PA, 1988), pp. 528–537.Google Scholar
22.Duda, J. L., Vrentas, J. S., Ju, S. T., and Lui, H. T., A.I.Ch.E.J. 28, 279 (1982).CrossRefGoogle Scholar
23.Song, J. H., Evans, J. R. G., Edirisinghe, M. J., and Twizell, E. H., in Advanced Ceramics for Structural and Tribiological Applications, edited by Hawthorne, H. M. and Troczynski, T. (The Met. Soc. of the Canadian Inst. of Mining, Metallurgy and Petroleum, Montreal, Canada, 1995), pp. 49–60.Google Scholar
24.Wheeler, A., Catalysis 2, 105 (1955).Google Scholar
25.Reyes, S. and Jensen, K. F., Chem. Eng. Sci. 40, 723 (1985).CrossRefGoogle Scholar
26.Scatterfield, C. N. and Cadle, P. J., Ind. Eng. Chem. Fundam. 7, 202 (1968).CrossRefGoogle Scholar
27.Partington, J. R., An Advanced Treatise on Physical Chemistry (Longmans, London, 1967), Vol. 1, p. 874.Google Scholar
28.Bondi, A. and Simkin, D. J., A.I.Ch.E.J. 6, 191 (1960).CrossRefGoogle Scholar
29.Dullien, F. A. L., Porous Media, Fluid Transport and Pore Structure (Academic Press, New York, 1979), p. 222.Google Scholar
30.Maddox, R. N. and Hines, A. L., Mass Transfer Fundamentals and Applications (Prentice-Hall, Englewood Cliffs, NJ, 1985), p. 151.Google Scholar
31.Twizell, E. H., Computational Methods for Partial Differential Equations (Ellis Horwood, Chichester, and John Wiley, New York, 1984), p. 212.Google Scholar
32.Smith, G. D., Numerical Solutions of Partial Differential Equations: Finite Difference Methods, 3rd ed. (Oxford University Press, Oxford, 1985), Chap. 3.Google Scholar
33.Forsythe, G. E. and Moler, C. B., Computer Solution of Liner Algebraic Systems (Prentice-Hall, Englewood Cliffs, NJ, 1967), p. 114.Google Scholar
34.Youngquist, G. R., D. Ind. Engrg. Chem. 62, 53 (1970).Google Scholar
35.Bao, Y. and Evans, J. R. G., J. Euro. Ceram. Soc. 8, 81 (1991).CrossRefGoogle Scholar