Properties of polysiloxane coated borosilicate lining blocks

To improve the thermal resistance of a porous borosilicate lining block, we prepared and applied polysiloxane-fumed silica-ethanol slurry on top of the block and fired the coating layer using a torch for 5 minutes at 800°C. We conducted magnified characterizations using a microscope and XRD analysis to observe phase transformations, and TGA-DTA analysis to determine the thermal resistance. Thermal characterizations showed improved heat resistance with relatively high polysiloxane content slurry. Cross-sectional optical microscope observation showed less melting near the surface and decreased pore formation area with higher polysiloxane content slurry. XRD analysis revealed that the block and coating layer were amorphous phases. TGA-DTA analysis showed an endothermic reaction at around 550°C as the polysiloxane in the coating layer reacted to form SiOC. Therefore, coating polysiloxane on a borosilicate block contributes to preventing the melting of the block at temperatures above 800oC.