| Author | S. Adjerid, J. E. Flaherty, W. Hillig, J. Hudson and M. S. Shephard |
|---|---|
| Title | Adaptive Method of Lines Techniques for Vapor Infiltration Problems |
| Year | 1994 |
| Pages | - - |
| Editor | - - |
| Abstract | Patibandla et al. [4,5] describe a reactive vapor infiltration (RVI) process for manufacturing fiber-reinforced ceramic composites where silicon carbide or Alumina fibers are mixed with molybdenum powder and pressed at room temperature to form a porous preform. The preform is exposed to a silicon tetra-chloride and hydrogen flow where molecular-surface reactions liberate Si which, when absorbed into the preform, reacts with Mo to form a molybdenum di-silicide matrix. As a first step in modeling the RVI process, we present a mathematical model of the diffusion of Si into a compressed-powder Mo pellet to form the matrix. The production of an intermediate silicide layer, the growth of the layer, and the volume expansion of the pellet are predicted. The resulting partial differential system is solved using an adaptive software system [2] that includes capabilities for automatic quadtree-structured mesh generation, mesh refinement/coarsening (h-refinement), method order variation (p-refinement), and mesh motion (r-refinement). Computational solutions of one- and two-dimensional problems indicate that the adaptive software is a robust and effective tool for addressing composite-processing problems. The mathematical model predicts the observed parabolic growth rate of the silicide layer and the volume expansion of the pellet to a high degree of accuracy. |
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