Disclosed herein are ultraviolet (UV) curable coating compositions that provide transparent, flexible, and abrasion-resistant coatings when cured on a substrate. The coating compositions comprise an adduct of a multifunctional acrylate monomer component and an amino-organofunctional silane; an organic solvent component; an acid; a colloidal silica component; and a multifunctional urethane acrylate oligomer component. The amino-organofunctional silane is represented by the formula XaSi[Q1(NHQ2)bNZH]4-a, where X is an alkoxy group having from 1 to 6 carbon atoms; Q1 and Q2 are the same or different divalent hydrocarbon groups; Z is a hydrogen or a monovalent hydrocarbon group; a is an integer from 1 to 3; and b is an integer from 0 to 6. Also disclosed herein are processes for preparing such coating compositions and articles comprising coatings cured from such coating compositions.