Preparation of Nanocristobalite and Its Effect on Some Properties of Two Component Automobile Clear Coats

In this paper, nanocristobalite was prepared by simple heat treatment of amorphous silica at 1470˚C for 2 hours. The XRD results confirmed that amorphous silica changed to cristobalite completely. The prepared cristobalite and crystaline microsilica (quartz) and two types amorphous of nanosilica (untreated and surface treated) were used to improve the mechanical properties of a two component polyurethane automotive clear coat. The effect of the nanosilicas and microsilica on the optical and mechanical properties of the clear coat was studied. It was revealed that all of the silicas added improved the hardness properties of the coatings, but some of them had a negative effect on the optical properties.Nanosilica (surface treated) improved optical propertiy and wear resistant. J. Color Sci. Tech. 2(2008), 23-29. © Institute for Colorants, Paint and Coatings.