Silication is the final process step in the production of reaction-sintered silicon carbide (Si-SiC), surface silicated carbon (C-SiC) and silicon impregnated carbon (C-SiC-Si). The green compacts pass through a vacuum chamber into a silicon melt or silicon atmosphere. The liquid or gaseous silicon penetrates the green compact and reacts with the carbon to form silicon carbide (SiC). Any areas of imperfection such as pores and cracks are filled with the silicon, however, and this restricts the use of these materials. The silicon is dissolved selectively (selective corrosion) by strong alkalis. In strong acid or dilute alkali environments, on the other hand, the silicated materials display exceptional resistance to corrosion.