Modeling of a silicon/silicon carbide pressureless infiltration process

During the experimental phase of this research, experimentalists discovered several small protrusions on the surface of silicon/silicon carbide metal matrix composites, which were created using a customized pressureless infiltration technique. These protrusions, called overfillings, differed in size and were spontaneously distributed on the surface of the infiltrated body. It was hypothesized that these overfillings were the result of the silicon’s large positive volume phase change. Through the use of several computer models, hypothesis of the previous experimental research was confirmed. It was ultimately determined that the overfillings are not the result of the shrinking silicon carbide skeleton, but are, instead, the result of the silicon’s phase change properties, which cause it to expand upon solidification. As the infiltrated body cools, the silicon changes from liquid to solid phase, expanding 10%. Because the silicon carbide skeleton is completely saturated with the liquid silicon, the liquid silicon is forced out of the composite as it solidifies, resulting in overfilling. Not only does this paper provide a detailed analysis of the computer modeling techniques used for the simulations and their correlating results, but this paper also explains the experimental research on which the computer models are founded.